WorldWideScience

Sample records for dendrochronology

  1. [Research advances in dendrochronology].

    Science.gov (United States)

    Fang, Ke-Yan; Chen, Qiu-Yan; Liu, Chang-Zhi; Cao, Chun-Fu; Chen, Ya-Jun; Zhou, Fei-Fei

    2014-07-01

    Tree-ring studies in China have achieved great advances since the 1990s, particularly for the dendroclimatological studies which have made some influence around the world. However, because of the uneven development, limited attention has been currently paid on the other branches of dendrochronology. We herein briefly compared the advances of dendrochronology in China and of the world and presented suggestions on future dendrochronological studies. Large-scale tree-ring based climate reconstructions in China are highly needed by employing mathematical methods and a high quality tree-ring network of the ring-width, density, stable isotope and wood anatomy. Tree-ring based field climate reconstructions provide potentials on explorations of climate forcings during the reconstructed periods via climate diagnosis and process simulation.

  2. An organismal view of dendrochronology

    Science.gov (United States)

    Kevin T. Smith

    2008-01-01

    An organism is the most basic unit of independent life. The tree-ring record is defined by organismal processes. Dendrochronology contributes to investigations far removed from organismal biology, e.g., archeology, climatology, disturbance ecology, etc. The increasing integration of dendrochronology into a diverse research community suggests an opportunity for a brief...

  3. Reconstructing Fire History: An Exercise in Dendrochronology

    Science.gov (United States)

    Lafon, Charles W.

    2005-01-01

    Dendrochronology is used widely to reconstruct the history of forest disturbances. I created an exercise that introduces the use of dendrochronology to investigate fire history and forest dynamics. The exercise also demonstrates how the dendrochronological technique of crossdating is employed to age dead trees and identify missing rings. I…

  4. Applications of PIXE in dendrochronology

    International Nuclear Information System (INIS)

    Revesz, P.; Mayer, J.W.; Vizkelethy, G.; Kuniholm, P.I.; Griggs, C.B.; Kuniholm, H.E.; Newton, M.W.; Tarter, S.L.

    1991-01-01

    The Bard Hall Ion Beam Facility has developed external proton beams at 1-3 MeV for ion-induced x-ray emission studies of artists' pigments and metallic printers inks. The authors have extended these PIXE measurements to analysis of Athenian Tetradrachms (5th and 6th centuries BC). In both pigment and coin studies they have compared PIXE analyses with those from XRF and electron micro probe for calibration purposes. The Aegean Dendrochronology Project has developed over 5500 years of tree-ring chronologies for the Aegean, Balkans, and Eastern Mediterranean. Included are forest sites adjacent to mining and smelting operations, also sites at the upper timberline where the annual growth-rings might be expected to have picked up fallout from volcanic activity around the world. A preliminary examination of selected rings by PIXE has shown remarkable differences from year to year in the deposition of various elements, notable Zn, Fe, and Cu. The authors propose to look at a number of selected annual ring sequences to see (1) whether one can chart the progress of known metallurgical activity; (2) whether one can find evidence for volcanic effects, both for absolutely-dated volcanoes such as Krakatoa, Tambora, and Sumbawa, and for problematic volcanoes such as Santorini/Thera

  5. DendroCT - Dendrochronology without damage

    DEFF Research Database (Denmark)

    Bill, Jan; Daly, Aoife; Johnsen, Øistein

    2012-01-01

    The paper describes an evaluation of the applicability of computer tomography in archaeological dendrochronology. Two different computer tomographs were tested, a . Siemens Somatom Emotion single slice scanner developed for medical use, and a . Nikon Metrology model . XT H 225 LC, which is an ind...

  6. Irregularities in the dendrochronological calibration curve

    International Nuclear Information System (INIS)

    Ottaway, J.H.; Ottaway, B.

    1975-01-01

    A discussion is presented on the reality or otherwise of short-term deviations from a linear or smooth curve relating conventional C-14 dates to dendrochronological measurements. The possibility of the effect of short-term changes in the earth's atmosphere and in the oceans, and particularly in their temperature, is considered. (U.K.)

  7. Dendrochronology of Utah Juniper (Juniperus osteosperma (Torr.) Little)

    Science.gov (United States)

    R. Justin Derose; Matthew F. Bekker; Roger Kjelgren; Brendan M. Buckley; James H. Speer; Eric B. Allen

    2016-01-01

    Utah juniper was a foundational species for the discipline of dendrochronology, having been used in the early 20th Century investigations of Mesa Verde, but has been largely ignored by dendrochronologists since. Here we present dendrochronological investigations of Utah juniper core and cross-sectional samples from four sites in northern Utah. We demonstrate that,...

  8. The Dendrochronological Dating of Timber Crossings in West Jutland, Denmark

    DEFF Research Database (Denmark)

    Daly, Aoife

    2006-01-01

    The dendrochronological analyses of a large number of timbers from two sites are described. Nybro causeway in west Jutland, Denmark, which was built in the 8th century AD, consists of numerous phases, identifiable due to the large number of dendrochronologically dated timbers, of which many had...

  9. Dendrochronology of Strain-Relaxed Islands

    International Nuclear Information System (INIS)

    Merdzhanova, T.; Kiravittaya, S.; Rastelli, A.; Stoffel, M.; Denker, U.; Schmidt, O.G.

    2006-01-01

    We report on the observation and study of tree-ring structures below dislocated SiGe islands (superdomes) grown on Si(001) substrates. Analogous to the study of tree rings (dendrochronology), these footprints enable us to gain unambiguous information on the growth and evolution of superdomes and their neighboring islands. The temperature dependence of the critical volume for dislocation introduction is measured and related to the composition of the islands. We show clearly that island coalescence is the dominant pathway towards dislocation nucleation at low temperatures, while at higher temperatures anomalous coarsening is effective and leads to the formation of a depletion region around superdomes

  10. Growth divergence: a challenging opportunity for dendrochronology

    Science.gov (United States)

    Buras, Allan; Sass-Klaassen, Ute; Wilmking, Martin

    2017-04-01

    Dendrochronology is an essential cornerstone of paleoclimatology and the evaluation of climate change impacts on forest ecosystems. However, a growing body of literature indicates that the standard dendrochronological approach may too rigorously neglect individualistic tree-growth (e.g. Wilmking et al., 2004, Buras et al., 2016). Amongst others, these studies showed convincing evidence that individual trees of the same species sampled at one site expressed different long-term growth patterns and therefore differing climate-growth relationships. This phenomenon is commonly termed growth divergence (GD) and possibly weakens our ability to correctly estimate past climate variability as discussed in the context of the so-called divergence phenomenon (D'Arrigo et al., 2008). In this context, climate change may naturally select for trees on the stand-level which are better adapted to future conditions. Although GD has been reported for several sites, the standard dendrochronological approach yet does not consider the existence of GD. A possible reason for this methodological persistence is the lack of detailed information on the frequency, magnitude, and impact of GD occurrence. To assess GD occurrence and related tree-individual variations in climate-growth response we conducted a global GD study by using 134 ring-width data representing 52 tree species and 16 genera distributed over 115 sites across 22 countries. Our analyses clearly reveal GD to be a common phenomenon as occurring in 85 % of all sites. GD was clearly related to the degree of tree-individual differences in climate-growth response. Respective transfer functions which appropriately accounted for GD by selection of tree-cohorts with a high share of long-term variance on average increased the precision and stability of tree-ring based climate reconstructions. Concluding, incorporation of GD assessments into the dendrochronological approach has a strong potential to improve the precision of our predictions

  11. Dendrochronology of strain-relaxed islands.

    Science.gov (United States)

    Merdzhanova, T; Kiravittaya, S; Rastelli, A; Stoffel, M; Denker, U; Schmidt, O G

    2006-06-09

    We report on the observation and study of tree-ring structures below dislocated SiGe islands (superdomes) grown on Si(001) substrates. Analogous to the study of tree rings (dendrochronology), these footprints enable us to gain unambiguous information on the growth and evolution of superdomes and their neighboring islands. The temperature dependence of the critical volume for dislocation introduction is measured and related to the composition of the islands. We show clearly that island coalescence is the dominant pathway towards dislocation nucleation at low temperatures, while at higher temperatures anomalous coarsening is effective and leads to the formation of a depletion region around superdomes.

  12. Dendrochronology of bristlecone pine, Pinus longaeva

    International Nuclear Information System (INIS)

    Ferguson, C.W.

    1979-01-01

    Since 1953 the Laboratory of Tree-Ring Research has conducted dendrochronological studies of bristlecone pine Pinus longaeva D.K. Bailey, sp. nov.) in the White Mountains of California. This research resulted in the establishment of a continuous tree-ring sequence of 8253 yr. The millennia-old pines have emerged as a unique source of chronological data and the precisely dated wood is essential to certain paleoenvironmental and geophysical investigations. Over 1000 dendrochronologically dated decade samples of bristlecone pine supplied to three C-14 laboratories have been used to calibrate the radiocarbon time scale for the past seven millennia, a development of far reaching consequences in the fields of archaeology and geology. In addition, recent advances in other methods of analyzing past climatic variability - techniques involving stable isotope ratios, amino acid racemization, remanent magnetism and trace element abundances - have greatly increased the demand for wood of known age and, hence, for chronology development. Spanning the past 7500 yr, 1138 prepared decade samples, with a total weight of nearly 16 kg are available for study. (author)

  13. TREE SELECTING AND TREE RING MEASURING IN DENDROCHRONOLOGICAL INVESTIGATIONS

    Directory of Open Access Journals (Sweden)

    Sefa Akbulut

    2004-04-01

    Full Text Available Dendrochronology is a method of dating which makes use of the annual nature of tree growth. Dendrochronology may be divided into a number of subfields, each of which covers one or more aspects of the use of tree ring data: dendroclimatology, dendrogeomorphology, dendrohydrology, dendroecology, dendroarchaelogy, and dendrogylaciology. Basic of all form the analysis of the tree rings. The wood or tree rings can aid to dating past events about climatology, ecology, geology, hydrology. Dendrochronological studies are conducted either on increment cores or on discs. It may be seen abnormalities on tree rings during the measurement like that false rings, missing rings, reaction wood. Like that situation, increment cores must be extracted from four different sides of each tree and be studied as more as on tree.

  14. A Dendrochronological Analysis of Red Oak Borer Abundance

    Science.gov (United States)

    Rose-Marie Muzika; Richard P. Guyette

    2004-01-01

    Unprecedented outbreaks of red oak borer (Enaphalodes rufulus Haldemann) have occurred in the lower Midwestern United States. Although generally not a mortality agent, red oak borer appears to contribute to general oak decline and mortality. The objective of this project was to explore dendrochronology as a means of determining the role of tree age,...

  15. The Tunguska event and Cheko Lake origin: dendrochronological analysis

    Czech Academy of Sciences Publication Activity Database

    Fantucci, R.; Serra, R.; Kletetschka, Günther; Di Martino, M.

    2015-01-01

    Roč. 14, č. 3 SI (2015), s. 345-357 ISSN 1473-5504 Institutional support: RVO:67985831 Keywords : cosmic body impact * collapse crater * dendrochronology * Tunguska * tree rings * Russia * Siberia Subject RIV: DB - Geology ; Mineralogy Impact factor: 1.184, year: 2015

  16. Dendrochronology in the dry tropics: the Ethiopian case

    NARCIS (Netherlands)

    Wils, T.; Sass-Klaassen, U.; Eshetu, Z.; Bräuning, A.; Gebrenirstos, A.; Couralet, C.; Robertson, I.; Touchan, R.; Koprowski, M.; Conway, D.; Briffa, K.R.; Beeckman, H.

    2011-01-01

    Dendrochronology is developing outside temperate and boreal regions. Over the past decade substantial progress has been made in Mediterranean and wet tropical regions. However, research in dry tropical regions, notably those of sub-Saharan Africa, has remained fragmentary. Here, we try to identify

  17. The role of dendrochronology in natural resource management

    Science.gov (United States)

    Ramzi Touchan; Malcolm Hughes

    2000-01-01

    The discipline of dendrochronology, that is, development and use of time series of annual growth rings of trees, is a set of techniques by which the annual growth layers of trees may be assigned to definite calendar years. The history of changes in the trees’ environment may be reconstructed using various properties of tree rings. In this paper we will discuss how tree...

  18. Dendrochronological Investigations of Valonia Oak Trees in Western Greece

    Directory of Open Access Journals (Sweden)

    Andreas Papadopoulos

    2016-06-01

    Full Text Available Background and Purpose: Valonia oak (Quercus ithaburensis subsp. macrolepis (Kotschy Hedge & Yalt. is an east Mediterranean endemic, xerothermic and deciduous tree of particular interest in forestry. There has been a growing demand lately to include the species in reforestations in Greece which also increased the interest to investigate its response to climate change. The main purpose of this research is to study valonia oak from a dendrochronological – dendroclimatological point of view within its Mediterranean distribution range. Materials and Methods: Sampling took place in characteristic valonia oak stands where cross sections or tree-cores were taken from 40 trees. The cross sections and the tree-cores were prepared and cross-dated using standard dendrochronological methods and tree-ring widths were measured to the nearest 0.001 mm using the Windendro software program. The ARSTAN program was used to standardize the tree-ring data and to calculate dendrochronological statistical parameters. The inter-annual variability of tree-ring width and the radial growth trend were examined. Finally, tree-ring widths to climate relationships were calculated by orthogonal regression in combination with the bootstrap procedure using master residual chronology and monthly precipitation, temperature data and scPDSI drought index, from October of the n-1 year up to November of the n year. Results: The master chronology of valonia oak trees in Western Greece reaches 365 years, with an average ring width of 0.89 mm and with mean sensitivity being 0.21. The variation of the tree-ring widths indicates the influence of climate and human intervention in the past. Tree-ring to climate relationships show that valonia oak growth is positively affected by precipitations in January and March and by drought reduction during June and July. Conclusions: Valonia oak in Western Greece is a species of great interest for dendrochronological and dendroclimatological studies

  19. Dendrochronological dating for the study of historical buildings

    Directory of Open Access Journals (Sweden)

    Mauro Bernabei

    2012-12-01

    Full Text Available This article addresses the discipline of dendrochronology and, especially, one of its most useful aspects for the study, restoration and appreciation of architectonic heritage: dating. In its pages it deals with the origin, foundations and principles of this technique, the requisites for its application, the different ways of obtaining samples, the use of statistics and the various difficulties, limitations and aspects of dating. Finally, it touches upon the ­field of dendroprovenance, that is, the technique used to discover the geographic origin of timber by means of concrete examples of works performed by the authors, such as the Church of the Nativity in Bethlehem, Palestine.

  20. Can dendrochronology procedures estimate historical Tree Water Footprint?

    Science.gov (United States)

    Fernandes, Tarcísio J. G.; Del Campo, Antonio D.; Molina, Antonio J.

    2013-04-01

    Whole estimates of tree water use are becoming increasingly important in forest science and forest scientists have long sought to develop reliable techniques to estimate tree water use. In this sense accurately determining or estimate the quantity of water transpired by trees and forests is important and can be used to determine "green" water footprint. The use of dendrochronology is relative common in the study of effects and interactions between growth and climatic variables, but few studies deal with the relationship with water footprint. The main objective of this study is determining the historical tree water-use in a planted stand by dendrochronological approaches. This study was performed in South-eastern Spain, in an area covered by 50-60 years old Pinus halepensis Mil. plantations with high tree density (ca.1288/ha) due to low forest management. The experimental set-up consisted of two plots (30x30m), one corresponding to a thinning treatment performed in 2008 (t10) and the other thinned in 1998 (t1) to assess the mid-term effects of thinning. After one year of thinning four representative trees were select in each plot to measure transpiration by heat pulse sensor (sapflow velocity, vs). The accumulated daily values of transpiration (L day-1) were estimated multiplying the values of vs by sapwood area of each selected tree. After transpiration measurements two cores per tree were taken for establishing the tree-rings chronologies. The cores were prepared, their ring-width were measured and standardised in basal area increment index (BAI-i) following usual dendrochronological methods. The dendrochronology analyses showed a general variability in ring width during the initial growth (15 years), while in the following years the width rings were very small, conditioned by climate. The year after thinning (1999 or 2009) all trees in the treatments showed significant increases in ring width. The average vs for t1 and t10 were 3.59 cm h-1 and 1.95 cm h-1, and

  1. Use of dendrochronology and dendrochemistry in environmental forensics: Does it meet the Daubert criteria?

    Science.gov (United States)

    Balouet, J.-C.; Smith, K.T.; Vroblesky, D.; Oudijk, G.

    2009-01-01

    Dendrochronological methods have been in use for more than 100 years, providing us a record of climate, human activities (archaeology), floods, fire, mudslides and other geological and biological events. More recently, dendrochemisty has been used to assess the time frames of the onset and existence of environmental contamination. This article assesses the scientific status of dendrochronology and dendrochemistry with respect to the admissibility of expert testimony and Daubert legal criteria. The purpose of this article is to identify the crucial scientific aspects of dendrochronology and dendrochemistry that address the Daubert criteria and Rule 702 as amended in 2000. To clarify terminology, dendrochronology is the precise and reliable assignment of the year of formation of tree rings. Dendroecology is the use of dendrochronology to understand ecological and environmental processes (Schweingruber, 1996). Dendrochemistry is a subdiscipline of dendrochronology that analyzes and interprets the wood chemistry of precisely dated tree rings. Forensic dendrochemistry applies dendrochemistry to resolve environmental disputes and generally deal with questions regarding the timing and/or the source of environmental incidents. One significant application of forensic dendrochemistry to expert testimony is to address issues of anthropogenic contamination. Forensic dendroecology is a similar term to forensic dendrochemistry, but forensic dendrochemistry will be used in this discussion as the latter term emphasizes the use of chemical detection methods. Because dendrochemistry is based on the foundation of dendrochronology, both the former specialty and the latter broader discipline will be discussed. ?? Taylor & Francis Group, LLC.

  2. Activation analysis and dendrochronology for estimating pollution histories

    International Nuclear Information System (INIS)

    Pillay, K.K.

    1976-01-01

    Neutron activation analysis of wood shavings from tree rings have shown that plant tissues grown through periods of varying environmental conditions keep permanent records of the trace elements they received though nutrients from their immediate surroundings. Detailed examination of several species of trees, along with dendrochronological data, suggest the possibilities of utilizing this technique for pollution monitoring as well as for developing valuable information for environmental modelling. The multielemental analyses of tree ring samples were done using multiple neutron irradiation and gamma-ray spectrometry using a high resolution Ge(Li) detector and a software orinted programmable multichannel analyzer. The neutron activation analysis consisted of two reactor irradiations and at least three countings at different decay periods. (T.G.)

  3. Maritime Coastlines: A New Ecosystem for Dendrochronological Analysis

    Science.gov (United States)

    Tucker, C. S.; Trepanier, J. C.; Harley, G. L.; DeLong, K. L.

    2017-12-01

    Research at the forefront of dendrochronology is investigating the usefulness of coastal tree-ring chronologies as climatic and environmental proxies. We hypothesize trees growing on the margin of freshwater-brackish environments are sensitive to climate variability similar to those in other climatically stressed regions (e.g., the arid Southwest U.S.) and can be used for dendrochronological analyses. This study explores rings from Pinus elliottii var. elliottii trees in the Grand Bay National Estuarine Research Reserve (GBNERR) growing less than 2 km from the Gulf of Mexico. Interseries correlations (r=0.68, p<0.01) and average mean sensitivities (r=0.57, p<0.01) for these trees are higher than most Southeast U.S. tree-ring studies. P. elliottii growth in this study is significantly correlated to Standardized Precipitation-Evapotranspiration Index (SPEI; r=0.5, p<0.05) during this species' growing season (May-October). Though precipitation and temperatures in the region are favorable for tree growth, coastal processes (e.g., saltwater intrusion, brackish groundwater, aerosolized salt) are substantial regulators of growth to the maritime trees at GBNERR, which makes individuals sensitive to climate variability. Significant correlations with pressure regimes during these trees' growing season suggest that as pressure decreases over the northern Gulf of Mexico coast, thus producing precipitation, pressure increases over the Caribbean. Previous research proposes that the Central U.S. receives important precipitation sources from the Caribbean through the `Maya Express', and our results show that this precipitation may also be important to northern Gulf of Mexico coastal ecosystems. P. elliottii growth in this study is significantly correlated to tropical cyclone storm surge and is not significantly correlated to tropical cyclone high winds, which supports other studies' hypotheses that Pinus spp. are susceptible to saltwater intrusion and not high winds. Additionally

  4. Advancing dendrochronological studies of fire in the United States

    Science.gov (United States)

    Harley, Grant L.; Baisan, Christopher H.; Brown, Peter M.; Falk, Donald A.; Flatley, William T.; Grissino-Mayer, Henri D.; Hessl, Amy; Heyerdahl, Emily K.; Kaye, Margot W.; Lafon, Charles W.; Margolis, Ellis; Maxwell, R. Stockton; Naito, Adam T.; Platt, William J.; Rother, Monica T.; Saladyga, Thomas; Sherriff, Rosemary L.; Stachowiak, Lauren A.; Stambaugh, Michael C.; Sutherland, Elaine Kennedy; Taylor, Alan H.

    2018-01-01

    Dendroecology is the science that dates tree rings to their exact calendar year of formation to study processes that influence forest ecology (e.g., Speer 2010, Amoroso et al., 2017). Reconstruction of past fire regimes is a core application of dendroecology, linking fire history to population dynamics and climate effects on tree growth and survivorship. Since the early 20th century when dendrochronologists recognized that tree rings retained fire scars (e.g., Figure 1), and hence a record of past fires, they have conducted studies worldwide to reconstruct the historical range and variability of fire regimes (e.g., frequency, severity, seasonality, spatial extent), the influence of fire regimes on forest structure and ecosystem dynamics, and the top-down (e.g., climate) and bottom-up (e.g., fuels, topography) drivers of fire that operate at a range of temporal and spatial scales. As in other scientific fields, continued application of dendrochronological techniques to study fires has shaped new trajectories for the science. Here we highlight some important current directions in the United States (US) and call on our international colleagues to continue the conversation with perspectives from other countries.

  5. Vulnerability of white spruce tree growth in interior Alaska in response to climate variability: dendrochronological, demographic, and experimental perspectives

    Science.gov (United States)

    A.D. McGuire; R.W. Ruess; A. Lloyd; J. Yarie; J.S. Clein; G.P. Juday

    2010-01-01

    This paper integrates dendrochronological, demographic, and experimental perspectives to improve understanding of the response of white spruce (Picea glauca (Moench) Voss) tree growth to climatic variability in interior Alaska. The dendrochronological analyses indicate that climate warming has led to widespread declines in white spruce growth...

  6. Combined dendrochronological and radiocarbon dating of six Russian icons from the 15th-17th centuries

    Science.gov (United States)

    Dolgikh, A. V.; Matskovsky, V. V.; Voronin, K. V.; Solomina, O. N.

    2017-06-01

    The results of dendrochronological and radiocarbon dating by means of accelerator mass spectrometry (AMS) of six medieval icons, originating from northern European Russia and painted on wooden panels made from Scots pine, dated to the 15th to 17th centuries are presented. The panels of each icon were studied using dendrochronology. Five to six AMS dates were obtained for four icons. Although five icons were dendro-dated successfully, one failed to be reliably cross-dated with the existing master tree-ring chronologies and it was dated by radiocarbon wiggle-matching. Dendrochronological dating and wiggle-matching of radiocarbon dates allowed us to determine the narrow chronological intervals of icon creation.

  7. Dendrochronology of Atriplex portulacoides and Artemisia maritima in Wadden Sea salt marshes

    NARCIS (Netherlands)

    Decuyper, M.; Slim, P.A.; Loon-Steensma, van J.M.

    2014-01-01

    The study uses a rather unusual method, dendrochronology, to investigate the growth and survival of Atriplex portulacoides L. and Artemisia maritima L. on salt marshes at two field sites on the Dutch North Sea barrier islands of Terschelling and Ameland. By providing information on longevity of

  8. [Cedrela odorata (Meliaceae) potential for dendrochronological studies in the Selva Central of Perú].

    Science.gov (United States)

    Pereyra Espinoza, Manuel Jesús; Inga Guillen, Gaby Janet; Santos Morales, Mariano; Arisméndiz Rodríguez, Rodolfo

    2014-06-01

    Despite the progress made during the past 20 years, searching dendrochronological potential in tropical and subtropical tree species, tropical dendrochronology, is still in a development stage. The aim of this research was to determine the potential of C. odorata for dendrochronological studies in the Selva Central of Perú. The tree-ring anatomical characteristics were carefully examined and we were able to develop a 215 year (1795-2 009) tree-ring chronology and correlate it with precipitation records. The tree-ring chronology was developed based on 47 series of 27 trees. Tree rings are clearly delimited by large pore diameters in earlywood and small ones in latewood associated with marginal and paratracheal parenchyma. The tree-ring chronology was related to precipitation records from Satipo and significant correlations were found with the previous rainy season and late dry season of the current growth period. Moreover, we found close relationship between tree growth and total precipitations of the hydrological period (December to September) for the interval 1990-2009. These results demonstrate the influence of rainfall at different stages of C. odorata radial growth. The good discrimination of annual rings, strong relationship with precipitation, the wide range and longevity of trees (200 years) make C. odorata a very promising species for dendrochronological studies in tropical and subtropical forest of America.

  9. Combining dendrochronology and matrix modelling in demographic studies: An evaluation for Juniperus procera in Ethiopia

    NARCIS (Netherlands)

    Couralet, C.; Sass, U.G.W.; Sterck, F.J.; Zuidema, P.A.

    2005-01-01

    Tree demography was analysed by applying dendrochronological techniques and matrix modelling on a static data set of Juniperus procera populations of Ethiopian dry highland forests. Six permanent sample plots were established for an inventory of diameters and 11 stem discs were collected for

  10. C14-Crash. The C14-method and dendrochronology, unveiling the illusion. 2. rev. ed.

    International Nuclear Information System (INIS)

    Bloess, C.; Niemitz, H.U.

    2000-01-01

    In this second edition of the book, which was published almost three years after the first edition, the authors reiterate and substantiate their doubts as to the basic theories underlying the radiocarbon dating method and the applicability of dendrochronology. (orig/CB) [de

  11. A dendrochronological fire history of Opeongo lookout in Algonquin Park, Ontario

    Science.gov (United States)

    Richard P. Guyette; Daniel C. Dey

    1995-01-01

    Fire-scarred stumps and natural snags of red pine (Pinus resinosa Ait.) on a 70-m tall bluff along Costello Creek, 2 km south of Lake Opeongo, were dated using dendrochronological methods. A fire scar chronology was constructed from 18 of the red pine samples that contained 34 dated fire scars.

  12. An experimental evaluation of fire history reconstruction using dendrochronology in white oak (Quercus alba)

    Science.gov (United States)

    Ryan W. McEwan; Todd F. Hutchinson; Robert D. Ford; Brian C. McCarthy

    2007-01-01

    Dendrochronological analysis of fire scars on tree cross sections has been critically important for understanding historical fire regimes and has influenced forest management practices. Despite its value as a tool for understanding historical ecosystems, tree-ring-based fire history reconstruction has rarely been experimentally evaluated. To examine the efficacy of...

  13. Using simulations and data to evaluate mean sensitivity (ζ) as a useful statistic in dendrochronology

    Science.gov (United States)

    Andrew G. Bunn; Esther Jansma; Mikko Korpela; Robert D. Westfall; James Baldwin

    2013-01-01

    Mean sensitivity (ζ) continues to be used in dendrochronology despite a literature that shows it to be of questionable value in describing the properties of a time series. We simulate first-order autoregressive models with known parameters and show that ζ is a function of variance and autocorrelation of a time series. We then use 500 random tree-ring...

  14. Using simulations and data to evaluate mean sensitivity (ζ) as a useful statistic in dendrochronology

    NARCIS (Netherlands)

    Bunn, A.G.; Jansma, E.; Korpela, M.; Westfall, R.D.; Baldwin, J.

    2013-01-01

    Mean sensitivity (ζ) continues to be used in dendrochronology despite a literature that shows it to be of questionable value in describing the properties of a time series. We simulate first-order autoregressive models with known parameters and show that ζ is a function of variance and

  15. Editorial: Papers from the 7th International Conference on Dendrochronology - Cultural Diversity, Environmental Variability

    Science.gov (United States)

    Margaret S. Devall; Elaine K. Sutherland

    2008-01-01

    The 7th International Conference on Dendrochronology - Cultural Diversity, Environmental Variability was held in Beijing, China from 11 to 17 June 2006. The conference was organized and hosted by the Institute of Botany, Chinese Academy of Sciences (IB_CAS) in conjunction with the International Union of Forest Research Organizations (IUFRO) Working Group 5.01.07 (Tree-...

  16. Ion Uptake Determination of Dendrochronologically-Dated Trees Using Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kenan Unlu; P.I. Kuniholm; D.K.H. Schwarz; N.O. Cetiner; J.J. Chiment

    2009-03-30

    Uptake of metal ions by plan roots is a function of the type and concentration of metal in the soil, the nutrient biochemistry of the plant, and the immediate environment of the root. Uptake of gold (Au) is known to be sensitive to soil pH for many species. Soil acidification due to acid precipitation following volcanic eruptions can dramatically increase Au uptake by trees. Identification of high Au content in tree rings in dendrochronologically-dated, overlapping sequences of trees allows the identification of temporally-conscribed, volcanically-influenced periods of environmental change. Ion uptake, specifically determination of trace amounts of gold, was performed for dendrochronologically-dated tree samples utilizing Neutron Activation Analysis (NAA) technique. The concentration of gold was correlated with known enviironmental changes, e.g. volcanic activities, during historic periods.

  17. Terahertz pulse imaging for tree-ring analysis: a preliminary study for dendrochronology applications

    International Nuclear Information System (INIS)

    Jackson, J B; Mourou, M; Whitaker, J F; Labaune, J; Mourou, G A; Duling, I N III; Williamson, S L; Lavier, C; Menu, M

    2009-01-01

    Time-domain terahertz reflection imaging is presented as a novel method of measuring otherwise inaccessible tree rings in wooden cultural heritage for the purpose of tree-ring crossdating. Axial and lateral two-dimensional terahertz images of obscured ring patterns are statistically validated with respect to their corresponding optical photographs via adapted dendrochronological methods. Results are compared to similar analysis of x-ray images of a wood specimen

  18. Dendrochronological potential of the alpine shrub Rhododendron nivale on the south-eastern Tibetan Plateau.

    Science.gov (United States)

    Liang, Eryuan; Eckstein, Dieter

    2009-09-01

    Shrubs and dwarf shrubs are wider spread on the Tibetan Plateau than trees and hence offer a unique opportunity to expand the present dendrochronological network into extreme environments beyond the survival limit of trees. Alpine shrublands on the Tibetan Plateau are characterized by rhododendron species. The dendrochronological potential of one alpine rhododendron species and its growth response to the extreme environment on the south-east Tibetan Plateau were investigated. Twenty stem discs of the alpine snowy rhododendron (Rhododendron nivale) were collected close to the tongue of the Zuoqiupu Glacier in south-east Tibet, China. The skeleton plot technique was used for inter-comparison between samples to detect the growth pattern of each stem section. The ring-width chronology was developed by fitting a negative exponential function or a straight line of any slope. Bootstrapping correlations were calculated between the standard chronology and monthly climate data. The wood of snowy rhododendron is diffuse-porous with evenly distributed small-diameter vessels. It has well-defined growth rings. Most stem sections can be visually and statistically cross-dated. The resulting 75-year-long standard ring-width chronology is highly correlated with a timberline fir chronology about 200 km apart, providing a high degree of confidence in the cross-dating. The climate/growth association of alpine snowy rhododendron and of this timberline fir is similar, reflecting an impact of monthly mean minimum temperatures in November of the previous year and in July during the year of ring formation. The alpine snowy rhododendron offers new research directions to investigate the environmental history of the Tibetan Plateau in those regions where up to now there was no chance of applying dendrochronology.

  19. Multiple dendrochronological responses to the eruption of Cinder Cone, Lassen Volcanic National Park, California

    Science.gov (United States)

    Sheppard, P.R.; Ort, M.H.; Anderson, K.C.; Clynne, M.A.; May, E.M.

    2009-01-01

    Two dendrochronological properties – ring width and ring chemistry – were investigated in trees near Cinder Cone in Lassen Volcanic National Park, northeastern California, for the purpose of re-evaluating the date of its eruption. Cinder Cone is thought to have erupted in AD 1666 based on ring-width evidence, but interpreting ring-width changes alone is not straightforward because many forest disturbances can cause changes in ring width. Old Jeffrey pines growing in Cinder Cone tephra and elsewhere for control comparison were sampled. Trees growing in tephra show synchronous ring-width changes at AD 1666, but this ring-width signal could be considered ambiguous for dating the eruption because changes in ring width can be caused by other events. Trees growing in tephra also show changes in ring phosphorus, sulfur, and sodium during the late 1660s, but inter-tree variability in dendrochemical signals makes dating the eruption from ring chemistry alone difficult. The combination of dendrochemistry and ring-width signals improves confidence in dating the eruption of Cinder Cone over the analysis of just one ring-growth property. These results are similar to another case study using dendrochronology of ring width and ring chemistry at Parícutin, Michoacán, Mexico, a cinder cone that erupted beginning in 1943. In both cases, combining analysis with ring width and ring chemistry improved confidence in the dendro-dating of the eruptions.

  20. Dating furniture and coopered vessels without waney edge - Reconstructing historical wood-working in Austria with the help of dendrochronology.

    Science.gov (United States)

    Klein, Andrea; Nemestothy, Sebastian; Kadnar, Julia; Grabner, Michael

    In the present study, 208 furniture and 168 coopered vessels from three Austrian museums were examined. Dendrochronology was used to date objects and to extract further information such as the necessary time for seasoning, wood loss through wood-working and methods of construction. In most cases sampling was done by sanding the cross section and making digital photographs using a picture frame and measuring digitally. The dendrochronological dates of the sampled furniture range between 1524 and 1937. The group of furniture includes cupboards, chests, tables, benches, commodes and beds. In many cases furniture was artfully painted and sometimes even shows a painted year. With the help of dendrochronology it was proved that some objects had been painted for some time after construction, or had been over-painted. Most furniture, however, was painted immediately after completion. In this case, the seasoning and storage time of the boards and the wood loss due to shaping can be verified. As an average value, 14 years have passed between the dendrochronological date of the outermost ring and the painting. The time span includes time of seasoning and storage and the rings lost by wood-working. This leads, on the one hand to a short storage time of less than 10 years and on the other hand to very little wood loss due to manufacturing. Those boards being less shaped turned out to be back panels of cupboards, therefore they are recommended to be sampled for dating. Coopered vessels were dated between 1612 and 1940. There was evidence that staves were split and not sawn in many cases. The staves were often split out of the outermost part of the tree and hardly any wood was worked away which was proved by the close dendrochronological dates of the single staves of a vessel. Since there is a short time of storage and only little wood loss through wood-working, dating of objects without a waney edge becomes reasonable.

  1. Dendrochronological analysis of the roof of the Nanebevzetí Panny Marie and Sv. Ondřeje church in Staré Hobzí

    Directory of Open Access Journals (Sweden)

    Michal Rybníček

    2004-01-01

    Full Text Available The work deals with dendrochronological analysis of the roof truss of parish church in the locality of Stare Hobzi. The dendrochronological analysis gave an integrated view on a complicated development of this building and it helped us to restore the succession of building adjustments performed on this building. The work is also to introduce the dendrochronology branch to people who participate on or direct perform building-historical research and to show them that it could be an essential helper in their work.

  2. Drought-adaptation potential in Fagus sylvatica: linking moisture availability with genetic diversity and dendrochronology.

    Directory of Open Access Journals (Sweden)

    Andrea R Pluess

    Full Text Available BACKGROUND: Microevolution is essential for species persistence especially under anticipated climate change scenarios. Species distribution projection models suggested that the dominant tree species of lowland forests in Switzerland, European beech (Fagus sylvatica L., might disappear from most areas due to expected longer dry periods. However, if genotypes at the moisture boundary of the species climatic envelope are adapted to lower moisture availability, they can serve as seed source for the continuation of beech forests under changing climates. METHODOLOGY/PRINCIPAL FINDINGS: With an AFLP genome scan approach, we studied neutral and potentially adaptive genetic variation in Fagus sylvatica in three regions containing a dry and a mesic site each (n(ind. = 241, n(markers = 517. We linked this dataset with dendrochronological growth measures and local moisture availabilities based on precipitation and soil characteristics. Genetic diversity decreased slightly at dry sites. Overall genetic differentiation was low (F(st = 0.028 and Bayesian cluster analysis grouped all populations together suggesting high (historical gene flow. The Bayesian outlier analyses indicated 13 markers with three markers differing between all dry and mesic sites and the others between the contrasting sites within individual regions. A total of 41 markers, including seven outlier loci, changed their frequency with local moisture availability. Tree height and median basal growth increments were reduced at dry sites, but marker presence/absence was not related to dendrochronological characteristics. CONCLUSION AND THEIR SIGNIFICANCE: The outlier alleles and the makers with changing frequencies in relation to moisture availability indicate microevolutionary processes occurring within short geographic distances. The general genetic similarity among sites suggests that 'preadaptive' genes can easily spread across the landscape. Yet, due to the long live span of

  3. Quantifications of dendrochronological information from contrasting microdensitometric measuring circumstances of experimental wood samples

    International Nuclear Information System (INIS)

    Helama, S.; Bégin, Y.; Vartiainen, M.; Peltola, H.; Kolström, T.; Meriläinen, J.

    2012-01-01

    We analyzed how the pretreatment method of Scots pine (Pinus sylvestris L.) wood specimens together with X-ray methodology applied for density analyses affect resulting tree-ring data and derived proxy-based climate information. We also evaluated whether these results from two contrasting laboratory circumstances could be homogenized by applying dendroclimatic statistical methods. For this study, we measured a pair of X-ray based microdensitometry datasets using double samples of subfossil and recent wood specimens. Dendrochronological information of earlywood and latewood series was examined to determine for alterations in the resulting data. We found that the level of overall density, its trend over cambial ages and the growth amplitude altered due to the sample pretreatment/density measuring exercise, which means that comparisons of heterogeneous datasets should be, in general, regarded cautiously. Dendrochronological standardization did, however, even out several potentially biasing influences from the differing overall densities and their trends. The two latewood (maximum) density chronologies yielded paleoclimatic reconstructions which both calibrated and verified satisfactorily with the instrumental warm-season (March–September) mean temperatures. The transfer functions were found to further equalize the differences between the two proxy records. We recommend (if no strictly homogenous data are available) reconciling similar data assemblages through transfer functions with multiple independent variables. - Highlights: ► We applied X-ray microdensitometry to treering analysis of modern and subfossil wood. ► We reveal the spectrum of methodology-dependent differences. ► We evaluate the climate change signals in X-ray based data of modern and subfossil tree-rings. ► Data homogenization was done using standardization and transfer function techniques. ► Methods allow careful utilization of tree-ring databases for climate change studies.

  4. Validating numerical simulations of snow avalanches using dendrochronology: the Cerro Ventana event in Northern Patagonia, Argentina

    Directory of Open Access Journals (Sweden)

    A. Casteller

    2008-05-01

    Full Text Available The damage caused by snow avalanches to property and human lives is underestimated in many regions around the world, especially where this natural hazard remains poorly documented. One such region is the Argentinean Andes, where numerous settlements are threatened almost every winter by large snow avalanches. On 1 September 2002, the largest tragedy in the history of Argentinean mountaineering took place at Cerro Ventana, Northern Patagonia: nine persons were killed and seven others injured by a snow avalanche. In this paper, we combine both numerical modeling and dendrochronological investigations to reconstruct this event. Using information released by local governmental authorities and compiled in the field, the avalanche event was numerically simulated using the avalanche dynamics programs AVAL-1D and RAMMS. Avalanche characteristics, such as extent and date were determined using dendrochronological techniques. Model simulation results were compared with documentary and tree-ring evidences for the 2002 event. Our results show a good agreement between the simulated projection of the avalanche and its reconstructed extent using tree-ring records. Differences between the observed and the simulated avalanche, principally related to the snow height deposition in the run-out zone, are mostly attributed to the low resolution of the digital elevation model used to represent the valley topography. The main contributions of this study are (1 to provide the first calibration of numerical avalanche models for the Patagonian Andes and (2 to highlight the potential of Nothofagus pumilio tree-ring records to reconstruct past snow-avalanche events in time and space. Future research should focus on testing this combined approach in other forested regions of the Andes.

  5. Drought-adaptation potential in Fagus sylvatica: linking moisture availability with genetic diversity and dendrochronology.

    Science.gov (United States)

    Pluess, Andrea R; Weber, Pascale

    2012-01-01

    Microevolution is essential for species persistence especially under anticipated climate change scenarios. Species distribution projection models suggested that the dominant tree species of lowland forests in Switzerland, European beech (Fagus sylvatica L.), might disappear from most areas due to expected longer dry periods. However, if genotypes at the moisture boundary of the species climatic envelope are adapted to lower moisture availability, they can serve as seed source for the continuation of beech forests under changing climates. With an AFLP genome scan approach, we studied neutral and potentially adaptive genetic variation in Fagus sylvatica in three regions containing a dry and a mesic site each (n(ind.) = 241, n(markers) = 517). We linked this dataset with dendrochronological growth measures and local moisture availabilities based on precipitation and soil characteristics. Genetic diversity decreased slightly at dry sites. Overall genetic differentiation was low (F(st) = 0.028) and Bayesian cluster analysis grouped all populations together suggesting high (historical) gene flow. The Bayesian outlier analyses indicated 13 markers with three markers differing between all dry and mesic sites and the others between the contrasting sites within individual regions. A total of 41 markers, including seven outlier loci, changed their frequency with local moisture availability. Tree height and median basal growth increments were reduced at dry sites, but marker presence/absence was not related to dendrochronological characteristics. CONCLUSION AND THEIR SIGNIFICANCE: The outlier alleles and the makers with changing frequencies in relation to moisture availability indicate microevolutionary processes occurring within short geographic distances. The general genetic similarity among sites suggests that 'preadaptive' genes can easily spread across the landscape. Yet, due to the long live span of trees, fostering saplings originating from dry sites and

  6. Hydrologic modelling and dendrochronology as tool of site-species adequation assessment in a changing climate context

    OpenAIRE

    Sohier, Catherine; Debruxelles, Jérôme; Brusten, Thomas; Bauwens, Alexandra; Claessens, Hugues; Degre, Aurore

    2010-01-01

    A hydrologic model is related to dendrochronological measurements performed in a 52 years old Spruce stand. The site is situated on a hillside with shallow and acid brown soil in the ecoregion of Ardenne (Wallonia, Southern Belgium). Hydrologic modelling The hydrologic simulation runs from 1971 to 2005 at daily time step. The model is based on an EPIC code, adapted to the site concerning soil reservoirs depth, characteristic water contents, root profile and water uptake. Weather data c...

  7. Introducing wood anatomical and dendrochronological aspects of herbaceous plants: applications of the Xylem Database to vegetation science

    Czech Academy of Sciences Publication Activity Database

    Büntgen, Ulf; Psomas, A.; Schweingruber, F. H.

    2014-01-01

    Roč. 25, č. 4 (2014), s. 967-977 ISSN 1100-9233 R&D Projects: GA MŠk(CZ) EE2.3.20.0248 Institutional support: RVO:67179843 Keywords : dendrochronology * dicotyledon * environmental change * functional traits * herbs * life form * non-forest vegetation * secondary growth * shrub * vegetation cover * wood anatomy * Xylem formation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.709, year: 2014

  8. Applications of dendrochronology and sediment geochronology to establish reference episodes for evaluations of environmental radioactivity

    Energy Technology Data Exchange (ETDEWEB)

    Waugh, W.J.; Carroll, J.; Abraham, J.D.; Landeen, D.S. [Roy F. Weston, Inc., U.S. Department of Energy, Grand Junction Office, 2597 B 3/4 Road, Grand Junction, CO 81503 (United States)

    1998-12-01

    Dendrochronology and sediment geochronology have been used to demonstrate retrospective monitoring of environmental radioactivity at United States Department of Energy (DOE) sites. {sup 14}C in annual growth rings of sagebrush preserved the temporal and spatial patterns of {sup 14}C resulting from dispersion downwind of a nuclear fuel processing facility at the Hanford Site in Washington State. As far as 10 km downwind of the facility, {sup 14}C concentrations were significantly higher in growth rings formed during a fuel processing episode than in rings produced during preoperational or postoperational episodes. An episode of uranium mill tailings deposition in pond sediments at the Grand Junction Office in Colorado was reconstructed using {sup 210}Pb geochronology constrained by a marker of peak {sup 137}Cs fallout. Uranium concentrations in ponds sediments deposited after the processing episode provide a reasonable cleanup standard. These reference episodes of environmental radioactivity reconstructed from measurements taken within contaminated environments can improve or replace reference area data as baseline information for dose reconstructions, risk assessments, and the establishment of cleanup standards. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  9. Applications of dendrochronology and sediment geochronology to establish reference episodes for evaluations of environmental radioactivity

    International Nuclear Information System (INIS)

    Waugh, W.J.; Carroll, J.; Abraham, J.D.; Landeen, D.S.

    1998-01-01

    Dendrochronology and sediment geochronology have been used to demonstrate retrospective monitoring of environmental radioactivity at United States Department of Energy (DOE) sites. 14 C in annual growth rings of sagebrush preserved the temporal and spatial patterns of 14 C resulting from dispersion downwind of a nuclear fuel processing facility at the Hanford Site in Washington State. As far as 10 km downwind of the facility, 14 C concentrations were significantly higher in growth rings formed during a fuel processing episode than in rings produced during preoperational or postoperational episodes. An episode of uranium mill tailings deposition in pond sediments at the Grand Junction Office in Colorado was reconstructed using 210 Pb geochronology constrained by a marker of peak 137 Cs fallout. Uranium concentrations in ponds sediments deposited after the processing episode provide a reasonable cleanup standard. These reference episodes of environmental radioactivity reconstructed from measurements taken within contaminated environments can improve or replace reference area data as baseline information for dose reconstructions, risk assessments, and the establishment of cleanup standards. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  10. Dendrochronological evaluation of historic changes in Lake Stirniai (Lithuania) water level

    International Nuclear Information System (INIS)

    Stasytyte, I.; Pakalnis, R.

    2005-01-01

    Full text: Dendrochronological research was carried out on Pinus sylvestris L. timber extracted from Lake Stirniai (55 o 15'04'' latitude (N) and 25 o 38'49'' longitude (E)). As a result, the tree ring width floating chronology spanning 213 years was compiled. Radiocarbon dating of the samples indicated that pines grew from 1103 ± 80 AD to 1315 ± 80 AD. Fragments of stems and roots of pines were found waterlogged in 1 m water layer. It means that in the Medieval Warm Period, the ground water level in the habitat of archaeological pines was below the nowadays lake level for at least by 1 m. The growth conditions became unfavourable in ∼ 1270 ± 80 AD. At the end of the 13 th century the climate became damper, lake transgression started, the trees of Scots pine became dry. The basic cause of transgression seems to be the bogged bed of the rivulet Stirna flowing out of the lake. This phenomenon was caused by the changed climate conditions. The formant analysis of the radial increase of the stems of archaeological Scots pine in Lake Stirniai revealed 52.9; 30.3; 21.1; 17.5; 15.0; 11.2 year long-term fluctuation cycles. Comparison of the obtained data with the present cycles is foreseen. (author)

  11. Dendrochronological evidence of cockchafer (Melolontha sp.) outbreaks in subfossil tree-trunks from Tovačov (CZ Moravia)

    Czech Academy of Sciences Publication Activity Database

    Kolář, Tomáš; Rybníček, M.; Tegel, W.

    2013-01-01

    Roč. 31, č. 1 (2013), s. 29-33 ISSN 1125-7865 R&D Projects: GA MŽP(CZ) SP/2D1/93/07; GA MŠk(CZ) ED1.1.00/02.0073; GA MŠk(CZ) EE2.3.20.0256 Institutional support: RVO:67179843 Keywords : Cockchafer * Oak * Tree-ring * Dendrochronology * Subfossil trunk Subject RIV: EH - Ecology, Behaviour Impact factor: 1.697, year: 2013 http://www.sciencedirect.com/science/article/pii/S1125786512000574

  12. An Updated Review of Dendrochronological Investigations in Mexico, a Megadiverse Country with a High Potential for Tree-Ring Sciences

    Directory of Open Access Journals (Sweden)

    Andrea C. Acosta-Hernández

    2017-05-01

    Full Text Available Dendrochronology is a very useful science to reconstruct the long-term responses of trees and other woody plants forming annual rings in response to their environment. The present review considered Mexico, a megadiverse country with a high potential for tree-ring sciences given its high climatic and environmental variability. We reviewed papers considering Mexican tree species that were published from 2001 to 2016. Most of these studies examined tree species from temperate forests, mainly in the pine and fir species. The review included 31 tree species. The most intensively sampled family and species were the Pinaceae and Douglas fir (Pseudotsuga menziessi (Mirb. Franco, respectively. Some threatened tree species were also studied. Dendrochronological investigations were mainly conducted in northern and central Mexico, with Durango being the most sampled state. The reviewed studies were mostly developed for hydroclimatic reconstructions, which were mainly based on the tree-ring width as a proxy for the climate. Tree-ring studies were carried out in both national and foreign institutions. Our review identified relevant research gaps for dendrochronologists such as: (i biomes which are still scarcely studied (e.g., tropical dry forests and (ii approaches still rarely applied to Mexican forests as dendroecology.

  13. Use of dendrochronological method in Pinus halepensis to estimate the soil erosion in the South East of Madrid (Spain).

    Science.gov (United States)

    Pérez-Rodríguez, Raquel; Marques, Maria Jose; Bienes, Ramón

    2007-05-25

    The rate of soil erosion in pine forests (Pinus halepensis) located in the Southeast of Madrid has been estimated using dendrochronological analysis based on the change in ring-growth pattern from concentric to eccentric when the root is exposed. Using 49 roots spread across five inclined areas, it has been found that the length and direction of the hillsides, as well as their vegetation cover affect the rate of erosion, while the slope itself does not. The erosion rates found for the different areas studied vary between 3.5 and 8.8 mm year(-1), that is between 40 and 101 t ha(-1) year(-1) respectively. These values are between 2 and 3 times greater than those predicted by USLE, for which this equation underestimates soil loss for Central Spain's Mediterranean conditions. Nonetheless, both methods (using dendrochronology to determine actual soil loss and theoretical prediction with USLE) are able to establish the same significant differences among the areas studied, allowing for the comparative estimate of the severity of the area's erosion problem.

  14. Dendrochronology and radiocarbon dating of conifer trees and buried logs from the Stanley River, Tasmania

    Energy Technology Data Exchange (ETDEWEB)

    Cook, E. [Columbia Univ., Palisades, NY (United States). Tree-Ring Lab; Barbetti, M.; Taylor, G.; Yu, Z.; Thompson, B.; Weeks, L. [Sydney Univ., Sydney, NSW (Australia). The NWG Macintosh Centre for Quaternary Dating; Buckley, B. [Tasmania Univ., Sandy Bay, TAS (Australia). Inst of Antarctic and Southern Ocean Studies

    1997-12-31

    Full text: Dendrochronological studies are being carried out on two endemic conifer species in the Stanley River area of western Tasmania. Living trees are growing along the river banks, adjacent floodplain areas, and occasionally on the lower hill-slopes. Many ancient logs are exposed in the bed and banks of the river, and several major excavations have been carried out in floodplain sediments up to a hundred metres distant from the present river channel. A tree-ring chronology for Huon pine (Lagarostrobos franklinii) now extends from the present back to 571 BC. This chronology has been constructed using cores from living trees (up to 1400 years old), sections from trees felled during logging operations in the early 1980s, and sections from subfossil logs in the river banks and floodplain sediments. Living celery-top pine (Phyllocladus aspleniifolius) trees are up to 500 years old, and a short chronology is being developed for this species as well. Large excavations have been carried out over several years in floodplain sediments, and sections have now been taken from a total of 350 subfossil logs. Both Huon and celery-top pine are represented in the collection. They range in age from >38 ka to modern, with good coverage for the periods 9-3.5 ka and from 2.5 ka to the present. A floating tree-ring chronology for Huon pine has been established for the period ca. 7200-3500 cal BP, and is gradually being augmented. In the collection of about 350 ancient conifer logs from the Stanley River, about 150 currently have known ages while the remaining 200 have yet to be studied. Most of them have ages less than 9000 cal BP, but about 10% of them are older. Four of them are more than 30,000 years old, and may be Last Interglacial in age. Nine of them are known to be between 18,000 and 10,000 years old, and six are between 10,000 and 9,000 years old. Our augmented collection has become an increasingly important archive for further tree-ring and carbon isotope studies. Paper

  15. Dendrochronology and radiocarbon dating of conifer trees and buried logs from the Stanley River, Tasmania

    International Nuclear Information System (INIS)

    Cook, E.; Barbetti, M.; Taylor, G.; Yu, Z.; Thompson, B.; Weeks, L.; Buckley, B.

    1997-01-01

    Full text: Dendrochronological studies are being carried out on two endemic conifer species in the Stanley River area of western Tasmania. Living trees are growing along the river banks, adjacent floodplain areas, and occasionally on the lower hill-slopes. Many ancient logs are exposed in the bed and banks of the river, and several major excavations have been carried out in floodplain sediments up to a hundred metres distant from the present river channel. A tree-ring chronology for Huon pine (Lagarostrobos franklinii) now extends from the present back to 571 BC. This chronology has been constructed using cores from living trees (up to 1400 years old), sections from trees felled during logging operations in the early 1980s, and sections from subfossil logs in the river banks and floodplain sediments. Living celery-top pine (Phyllocladus aspleniifolius) trees are up to 500 years old, and a short chronology is being developed for this species as well. Large excavations have been carried out over several years in floodplain sediments, and sections have now been taken from a total of 350 subfossil logs. Both Huon and celery-top pine are represented in the collection. They range in age from >38 ka to modern, with good coverage for the periods 9-3.5 ka and from 2.5 ka to the present. A floating tree-ring chronology for Huon pine has been established for the period ca. 7200-3500 cal BP, and is gradually being augmented. In the collection of about 350 ancient conifer logs from the Stanley River, about 150 currently have known ages while the remaining 200 have yet to be studied. Most of them have ages less than 9000 cal BP, but about 10% of them are older. Four of them are more than 30,000 years old, and may be Last Interglacial in age. Nine of them are known to be between 18,000 and 10,000 years old, and six are between 10,000 and 9,000 years old. Our augmented collection has become an increasingly important archive for further tree-ring and carbon isotope studies

  16. A likelihood-based time series modeling approach for application in dendrochronology to examine the growth-climate relations and forest disturbance history

    Science.gov (United States)

    A time series intervention analysis (TSIA) of dendrochronological data to infer the tree growth-climate-disturbance relations and forest disturbance history is described. Maximum likelihood is used to estimate the parameters of a structural time series model with components for ...

  17. Charcoal from a prehistoric copper mine in the Austrian Alps: dendrochronological and dendrological data, demand for wood and forest utilisation.

    Science.gov (United States)

    Pichler, Thomas; Nicolussi, Kurt; Goldenberg, Gert; Hanke, Klaus; Kovács, Kristóf; Thurner, Andrea

    2013-02-01

    During prehistory fire-setting was the most appropriate technique for exploiting ore deposits. Charcoal fragments found in the course of archaeological excavations in a small mine called Mauk E in the area of Schwaz/Brixlegg (Tyrol, Austria) are argued to be evidence for the use of this technology. Dendrochronological analyses of the charcoal samples yielded calendar dates for the mining activities showing that the exploitation of the Mauk E mine lasted approximately one decade in the late 8th century BC. Dendrological studies show that the miners utilised stem wood of spruce and fir from forests with high stand density for fire-setting and that the exploitation of the Mauk E mine had only a limited impact on the local forests.

  18. Integrating Dendrochronology, Climate and Satellite Remote Sensing to Better Understand Savanna Landscape Dynamics in the Okavango Delta, Botswana

    Directory of Open Access Journals (Sweden)

    Jane Southworth

    2013-11-01

    Full Text Available This research examines the integration and potential uses of linkages between climate dynamics, savanna vegetation and landscape level processes within a highly vulnerable region, both in terms of climate variability and social systems. We explore the combined applications of two time-series methodologies: (1 climate signals detected in tree ring growth, from published literature, chronologies from the International Tree-Ring Data Bank, and minimal preliminary field data; and (2 new primary production (NPP data of vegetation cover over time derived from remotely sensed analyses. Both time-series are related to the regional patterns of precipitation, the principle driver of plant growth in the area. The approach is temporally and spatially multiscalar and examines the relationships between vegetation cover, type and amount, and precipitation shifts. We review literature linking dendrochronology, climate, and remotely sensed imagery, and, in addition, provide unique preliminary analyses from a dry study site located on the outer limit of the Okavango Delta. The work demonstrates integration across the different data sources, to provide a more holistic view of landscape level processes occurring in the last 30-50 years. These results corroborate the water-limited nature of the region and the dominance of precipitation in controlling vegetation growth. We present this integrative analysis of vegetation and climate change, as a prospective approach to facilitate the development of long-term climate/vegetation change records across multiple scales.

  19. Non-invasive dendrochronology of late-medieval objects in Oslo: refinement of a technique and discoveries

    Science.gov (United States)

    Daly, Aoife; Streeton, Noëlle L. W.

    2017-06-01

    A technique for non-invasive dendrochronological analysis of oak was developed for archaeological material, using an industrial CT scanner. Since 2013, this experience has been extended within the scope of the research project `After the Black Death: Painting and Polychrome Sculpture in Norway'. The source material for the project is a collection of late-medieval winged altarpieces, shrines, polychrome sculpture, and fragments from Norwegian churches, which are owned by the Museum of Cultural History, University of Oslo. The majority cannot be sampled, and many are too large to fit into the CT scanner. For these reasons, a combined approach was adopted, utilizing CT scanning where possible, but preceded by an `exposed-wood' imaging technique. Both non-invasive techniques have yielded reliable results, and CT scanning has confirmed the reliability of the imaging technique alone. This paper presents the analytical methods, along with results from two of the 13 objects under investigation. Results for reliable dates and provenances provide new foundations for historical interpretations.

  20. Dendrochronological study of the endangered shrub Vella pseudocytisus subsp. paui (Brassicaceae: implications for its recovery and conservation

    Directory of Open Access Journals (Sweden)

    Génova, Mar

    2013-12-01

    Full Text Available Dendrochronology is useful to determine plant longevity, to provide insights into the structure and dynamics of plant populations and to study the relationships between growth and environmental determinants. The dendrochronology of endangered shrubs is unexplored, although their use represents an opportunity to produce better conservation guidelines. We collected for this study 63 samples from already dead specimens of Vella pseudocytisus subsp. paui (Brassicaceae, an endangered Spanish endemism from three localities. We analyzed the relationship between ring data and plant size to determine the accuracy of using size as a proxy for plant age. We also explored the relationships between ring data and environmental variables to detect growth determinants. This shrub showed a high longevity as older individuals presented nearly 50 growth rings. The relationship between age and size is weak although it could be established based on the logarithmic function of plant biovolume. Significant relationships were found between rainfall and ring widths, showing that water limited annual growth. Finally, age structure characterized differences among populations, highlighting the effects of disturbance and land use. These results provided new opportunities for management within the ongoing recovery plan for the species.La dendrocronología es útil para determinar la longevidad de la planta, proporcionar información sobre la estructura y dinámica de las poblaciones vegetales y estudiar las relaciones entre el crecimiento y las variables ambientales. Hasta ahora no se había hecho uso de la dendrocronología en arbustos en peligro de extinción, aunque su empleo puede mejorar las directrices de conservación. En este estudio se han recolectado 63 especímenes ya muertos de tres localidades de Vella pseudocytisus subsp. paui (Brassicaceae, un endemismo español en peligro de extinción. Se han analizado las relaciones entre los grosores del anillo de

  1. A novel dendrochronological approach reveals drivers of carbon sequestration in tree species of riparian forests across spatiotemporal scales.

    Science.gov (United States)

    Rieger, Isaak; Kowarik, Ingo; Cherubini, Paolo; Cierjacks, Arne

    2017-01-01

    Aboveground carbon (C) sequestration in trees is important in global C dynamics, but reliable techniques for its modeling in highly productive and heterogeneous ecosystems are limited. We applied an extended dendrochronological approach to disentangle the functioning of drivers from the atmosphere (temperature, precipitation), the lithosphere (sedimentation rate), the hydrosphere (groundwater table, river water level fluctuation), the biosphere (tree characteristics), and the anthroposphere (dike construction). Carbon sequestration in aboveground biomass of riparian Quercus robur L. and Fraxinus excelsior L. was modeled (1) over time using boosted regression tree analysis (BRT) on cross-datable trees characterized by equal annual growth ring patterns and (2) across space using a subsequent classification and regression tree analysis (CART) on cross-datable and not cross-datable trees. While C sequestration of cross-datable Q. robur responded to precipitation and temperature, cross-datable F. excelsior also responded to a low Danube river water level. However, CART revealed that C sequestration over time is governed by tree height and parameters that vary over space (magnitude of fluctuation in the groundwater table, vertical distance to mean river water level, and longitudinal distance to upstream end of the study area). Thus, a uniform response to climatic drivers of aboveground C sequestration in Q. robur was only detectable in trees of an intermediate height class and in taller trees (>21.8m) on sites where the groundwater table fluctuated little (≤0.9m). The detection of climatic drivers and the river water level in F. excelsior depended on sites at lower altitudes above the mean river water level (≤2.7m) and along a less dynamic downstream section of the study area. Our approach indicates unexploited opportunities of understanding the interplay of different environmental drivers in aboveground C sequestration. Results may support species-specific and

  2. Dendrochronology as a source of data for landslide activity maps – an example from Beskid Żywiecki Mountains (Western Carpathians, Poland

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    Łuszczyńska Katarzyna

    2017-09-01

    Full Text Available We applied dendrochronological methods for dating landslide activity in the study area (3.75 km2, on the slopes of Sucha Mountain (1040 m a.s.l., in the Beskid Żywiecki Mountains, in the Western Carpathians. 46 sampling sites were distributed throughout the study area. At each site we sampled 1-3 coniferous trees: Norway spruces (Picea abies Karst. and/or silver firs (Abies alba Mill.. From each tree 2 cores were sampled: one from the upslope and the other from the downslope side of the stem. Based on tree-ring widths measured for opposite sides of stems we have calculated eccentricity index values and dated past landslide events. Mean frequency of landslides was obtained for each sampling site. Finally, the data was interpolated into a map of landslide activity. Inverse Distance Weighting (IDW interpolation has been applied. For most of the study area we found medium (19 sites and low (23 sites levels of landslide activity. The highest level of activity was recorded for the largest landslide slope and for the one small landslide. The study conducted on Sucha Mountain has shown that dendrochronology can be an effective method for analysing landslide activity and may be useful in further studies, including those for landslide hazard and risk assessments.

  3. Comparison of Cottonwood Dendrochronology and Optically Stimulated Luminescence Geochronometers Along a High Plains Meandering River, Powder River, Montana, USA

    Science.gov (United States)

    Hasse, T. R.; Schook, D. M.

    2017-12-01

    significant inherited ages due to partial bleaching during sediment transport in this high plains river with high suspended sediment loads. The dendrochronology of the adjacent cottonwood trees then offers an independent measurement of the inherited age of the OSL samples.

  4. Dendrochronological dating of large woody debris on the example of Morávka River and Černá Opava River

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    Michal Rybníček

    2010-01-01

    Full Text Available Woody debris is an inseparable part of natural river channels. In a river ecosystem it affects the hydraulic, hydrological and morphological properties of the channel, and it is also of a biological significance. However, besides the positive effects, the woody debris can also have a negative impact, e.g. the reduction of the flow profile capacity or the destruction of waterside buildings. With the de­ve­lop­ment of log floating and timber trade, the woody debris started to be removed from the channels. Currently, within the process of stream revitalization, woody debris is being artificially placed into ri­vers. This paper deals with the possible dendrochronological dating of large woody debris (LWD and wood jams in the river channel and the riparian zone. Two sites have been chosen for the research, the Morávka River and the Černá Opava River. These sites have been chosen because of two dif­fe­rent types of riparian stands. The banks of the Morávka River are a soft wood floodplain forest (350 m ASL; the Černá Opava River has stands with nearly a hundred percent proportion of spruce (600 m ASL. The results of the research show that the species with diffuse-porous wood structure are very hard to date on the basis of Pressler borer cores. On the other hand, the sites with softwood species are easi­ly datable, especially if the trunks contain more than 40 tree-rings. At these sites it is possible to use the dendrochronological dating for the establishment of the temporal dynamics of the woody debris input in the river ecosystem.

  5. C14-Crash. The C14-method and dendrochronology, unveiling the illusion. 2. rev. ed.; C14-Crash. Das Ende der Illusion, mit Radiokarbonmethode und Dendrochronologie datieren zu koennen

    Energy Technology Data Exchange (ETDEWEB)

    Bloess, C.; Niemitz, H.U.

    2000-07-01

    In this second edition of the book, which was published almost three years after the first edition, the authors reiterate and substantiate their doubts as to the basic theories underlying the radiocarbon dating method and the applicability of dendrochronology. (orig/CB) [German] In dieser zweiten Auflage des Buches, die knapp drei Jahre nach der ersten erschien, vertiefen die Autoren ihre Zweifel an den grundlegenden Theorien und den bisherigen Resultaten der Radiokarbonmethode und der Dendrochronologie. (orig./CB)

  6. Radiocarbon dating and Dendrochronology for Statigraphic Units near Tebano, Senio Northern Apennines - Time frame of Climatic Fluctuation at the onset of the Younger Dryas

    Science.gov (United States)

    Eggenschwiler, Loren; Hajdas, Irka; Cherubini, Paolo; Picotti, Vincenzo; Saurer, Matthias

    2017-04-01

    The presence of Pinus [sylvestris] provides an insight into dramatic events due to climatic changes. Several major and minor climatic fluctuations have had a strong impact on terrestrial and marine environments since the last glacial period to present day (Ravazzi et al. 2006). This study aims to describe the response of a fluvial environment through the use of dendrochronology and stratigraphy. Here, we intend to get a better understanding of how these climatic fluctuations affect the behavior of the Senio River (Lotter et al. 1992). In Tebano, Italy, several Pinus sylvestris subfossil trunks were discovered during excavation for an irrigation pool. Subfossil samples were collected to analyze the climate during the Younger Dryas (11,000 years BP) in detail. Charcoal samples from the Bubano clay quarry extend our research to further to 35,500 cal. years BP. The combination of dendrochronology along with stratigraphy allowed us to examine the climate at a detailed local and apply it to a broader spectrum. Tree-ring measurements and cross dating provided a better understanding and verification of extreme events that occurred during the lifespans of the trees. The use of stable isotopes indicates the extreme conditions that occurred. Radiocarbon dating validates the age of the samples and what geological period they come from. Along with stratigraphy, we were able to compile depth data to create a sediment curve. Using various methods throughout this study, we discovered the climatic situation of Pinus 11,000 years BP and are able to compare them with samples from today. These present day samples mark two of the southernmost extents of the Pinus population. We were then able to comprehend the magnitude of sediment supply and precipitation. Through this collection of methods and data, we are able to understand the influence of climate change in the past and the potential changes of the future. REFERENCES Lotter, A. F.; Eicher, U.; Siegenthaler, U.; Birks, H. J. B

  7. Dendro-chronological analysis of fossilised wood in order to reconstruct the post-ice-age history of glaciers; Dendrochronologische Auswertung fossiler Hoelzer zur Rekonstruktion der nacheiszeitlichen Gletschergeschichte

    Energy Technology Data Exchange (ETDEWEB)

    Holzhauser, H.

    2008-07-01

    Around the middle of the 19th century, alpine glaciers advanced to their last maximum extension within the Holocene (the last 11'600 years). Some of the glaciers, especially the Great Aletsch and Gorner, penetrated deeply into wooded land and destroyed numerous trees. Not only were trees destroyed but also valuable arable farmland, alpine farm buildings and dwelling houses. Since the last maximum extension in the 19th century the retreat of the glaciers has accelerated revealing, within the glacier forefields, the remainders of trees once buried. Some of this fossil wood is found in the place where it grew (in situ). Often the wood dates back to a time before the last glacier advance, most of it is several thousands of years old because glacial advance and retreat periods occurred repeatedly within the Holocene. This paper shows the characteristics of fossil wood and how it can be analysed to reconstruct glacial history. It will be demonstrated how glacier length variation can be exactly reconstructed with help of dendrochronology. Thanks to the very exact reconstruction of the glacier length change during the advance periods in the 14th and 16th centuries, the velocities of both the Gorner and Great Aletsch glaciers can be estimated. They range between 7-8 and 20 m per year, in the case of the Gorner glacier, and between 7-8 and 36 m per year, in the case of the Great Aletsch glacier. (author)

  8. Dendrochronologically dated pine stumps document phase-wise bog expansion at a northwest German site between ca. 6700 and ca. 3400 BC

    Science.gov (United States)

    Maike Achterberg, Inke Elisabeth; Eckstein, Jan; Birkholz, Bernhard; Bauerochse, Andreas; Leuschner, Hanns Hubert

    2018-01-01

    The investigated northwest German mire site at Totes Moor is densely covered with subfossil pine stumps (Pinus sylvestris L.) from the fen-bog transition. This facilitates the spatio-temporal reconstruction of mire development, which is based on 212 in situ tree stumps in the case study presented here. Six dendrochronologically dated site chronologies together cover 2345 years between 6703 and 3403 BC. The gaps in between are 6 to 550 years long. Additionally, a floating chronology of 309 years, containing 30 trees, was radiocarbon-dated to the beginning of the 7th millennium cal BC. Peat-stratigraphical survey was carried out additionally, and elevations a.s.l. were determined at several locations. Tree dying-off phases, which indicate water level rise at the site, mostly in context of the local fen-bog transition, are evident for ca. 6600-6450, ca. 6350-5750, ca. 5300-4900, ca. 4700-4550, ca. 3900-3850, ca. 3700-3600, ca. 3500-3450 and ca. 3400 BC. The spatial distribution of the dated in situ trees illustrates the phase-wise expansion of raised bog over fen peat at the site. The documented bog expansion pulses likely correspond to climatic wet sifts.

  9. Methodological Aspects of the Potential Use of Dendrochronological Techniques When Analyzing the Long-Term Impact of Tourism on Protected Areas.

    Science.gov (United States)

    Ciapała, Szymon; Adamski, Paweł

    2015-01-01

    Intensification of pedestrian tourism causes damage to trees near tourist tracks, and likewise changes the soil structure. As a result, one may expect that annual amount of trees growing near tracks is significantly lower than deeper in the forest. However, during the study of the long-term impact of tourism on the environment (determined from tree increment dynamics), some methodological problems may occur. It is particularly important in protected areas where law and administrative regulations related to nature conservation force research to be conducted using small samples. In this paper we have analyzed the data collected in the Polish part of the Tatra National Park in the two study plots divided into two zones each: the area directly under the influence of the tourist's trampling and the control group. The aim of such analyses was to present the potential effects of the factors which may affect the results of dendrochronological analysis: (i) small size of samples that affects their representativeness, (ii) spatial differences in the rates of the process, as a result of spatial variability of environmental factors and (iii) temporal differences in the rates of the process. This study confirms that the factors mentioned above could significantly influence the results and should be taken into consideration during the analysis.

  10. Methodological Aspects of the Potential Use of Dendrochronological Techniques When Analyzing the Long-Term Impact of Tourism on Protected Areas.

    Directory of Open Access Journals (Sweden)

    Szymon Ciapała

    Full Text Available Intensification of pedestrian tourism causes damage to trees near tourist tracks, and likewise changes the soil structure. As a result, one may expect that annual amount of trees growing near tracks is significantly lower than deeper in the forest. However, during the study of the long-term impact of tourism on the environment (determined from tree increment dynamics, some methodological problems may occur. It is particularly important in protected areas where law and administrative regulations related to nature conservation force research to be conducted using small samples. In this paper we have analyzed the data collected in the Polish part of the Tatra National Park in the two study plots divided into two zones each: the area directly under the influence of the tourist's trampling and the control group. The aim of such analyses was to present the potential effects of the factors which may affect the results of dendrochronological analysis: (i small size of samples that affects their representativeness, (ii spatial differences in the rates of the process, as a result of spatial variability of environmental factors and (iii temporal differences in the rates of the process. This study confirms that the factors mentioned above could significantly influence the results and should be taken into consideration during the analysis.

  11. Growth and Its Relationship to Individual Genetic Diversity of Mountain Hemlock (Tsuga mertensiana at Alpine Treeline in Alaska: Combining Dendrochronology and Genomics

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    Jeremy S. Johnson

    2017-11-01

    Full Text Available Globally, alpine treelines are characterized as temperature-limited environments with strong controls on tree growth. However, at local scales spatially heterogeneous environments generally have more variable impacts on individual patterns of tree growth. In addition to the landscape spatial heterogeneity there is local variability in individual tree genetic diversity (level of individual heterozygosity. It has been hypothesized that higher individual heterozygosity will result in more consistent patterns of growth. In this article, we combine genomics and dendrochronology to explore the relationship between individual genetic diversity and tree growth at a mountain hemlock (Tsuga mertensiana Bong. Carr alpine treeline on the Kenai Peninsula, Alaska, USA. We correlated average observed individual heterozygosity with average tree-ring width and variance in tree-ring width within individuals to test the hypothesis that trees with higher individual heterozygosity will also have more consistent growth patterns, suggesting that they may be more resilient to climate and environmental fluctuations at the alpine treeline. Our results showed that there was no significant relationship between tree growth and individual heterozygosity. However, there was a significant positive relationship between average tree-ring width and variance in tree-ring width implying that overall, fast growing trees in stressful environments, such as the alpine treeline, grow unstably regardless of the level of individual heterozygosity.

  12. To core, or not to core: the impact of coring on tree health and a best-practice framework for collecting dendrochronological information from living trees.

    Science.gov (United States)

    Tsen, Edward W J; Sitzia, Tommaso; Webber, Bruce L

    2016-11-01

    Trees are natural repositories of valuable environmental information that is preserved in the growth and structure of their stems, branches and roots. Dendrochronological analyses, based on the counting, crossdating and characterisation of incrementally formed wood rings, offer powerful insights for diverse fields including ecology, climatology and archaeology. The application of this toolset is likely to increase in popularity over coming decades due to advances in the field and a reduction in the cost of analyses. In research settings where the continued value of living trees subject to dendrochronological investigation is important, the use of an increment bore corer to extract trunk tissue is considered the best option to minimise negative impacts on tree health (e.g. stress and fitness). A small and fragmented body of literature, however, reports significant after-effects, and in some cases fatal outcomes, from this sampling technique. As it stands, the literature documenting increment bore coring (IBC) impacts lacks experimental consistency and is poorly replicated, making it difficult for prospective users of the method to assess likely tree responses to coring. This paucity of information has the potential to lead to destructive misuse of the method and also limits its safe implementation in circumstances where the risk of impacts may be appropriate. If IBC is to fulfil its potential as a method of choice across research fields, then we must first address our limited understanding of IBC impacts and provide a framework for its appropriate future use. Firstly, we review the historical context of studies examining the impacts of IBC on trees to identify known patterns, focal issues and biases in existing knowledge. IBC wound responses, particularly those that impact on lumber quality, have been the primary focus of prior studies. No universal treatment was identified that conclusively improved wound healing and few studies have linked wound responses to tree

  13. Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

    Science.gov (United States)

    Petrillo, M.; Cherubini, P.; Fravolini, G.; Ascher, J.; Schärer, M.; Synal, H.-A.; Bertoldi, D.; Camin, F.; Larcher, R.; Egli, M.

    2015-09-01

    Due to the large size and highly heterogeneous spatial distribution of deadwood, the time scales involved in the coarse woody debris (CWD) decay of Picea abies (L.) Karst. and Larix decidua Mill. in Alpine forests have been poorly investigated and are largely unknown. We investigated the CWD decay dynamics in an Alpine valley in Italy using the five-decay class system commonly employed for forest surveys, based on a macromorphological and visual assessment. For the decay classes 1 to 3, most of the dendrochronological samples were cross-dated to assess the time that had elapsed since tree death, but for decay classes 4 and 5 (poorly preserved tree rings) and some others not having enough tree rings, radiocarbon dating was used. In addition, density, cellulose and lignin data were measured for the dated CWD. The decay rate constants for spruce and larch were estimated on the basis of the density loss using a single negative exponential model. In the decay classes 1 to 3, the ages of the CWD were similar varying between 1 and 54 years for spruce and 3 and 40 years for larch with no significant differences between the classes; classes 1-3 are therefore not indicative for deadwood age. We found, however, distinct tree species-specific differences in decay classes 4 and 5, with larch CWD reaching an average age of 210 years in class 5 and spruce only 77 years. The mean CWD rate constants were 0.012 to 0.018 yr-1 for spruce and 0.005 to 0.012 yr-1 for larch. Cellulose and lignin time trends half-lives (using a multiple-exponential model) could be derived on the basis of the ages of the CWD. The half-lives for cellulose were 21 yr for spruce and 50 yr for larch. The half-life of lignin is considerably higher and may be more than 100 years in larch CWD.

  14. Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

    Science.gov (United States)

    Petrillo, Marta; Cherubini, Paolo; Fravolini, Giulia; Marchetti, Marco; Ascher-Jenull, Judith; Schärer, Michael; Synal, Hans-Arno; Bertoldi, Daniela; Camin, Federica; Larcher, Roberto; Egli, Markus

    2016-03-01

    Due to the large size (e.g. sections of tree trunks) and highly heterogeneous spatial distribution of deadwood, the timescales involved in the coarse woody debris (CWD) decay of Picea abies (L.) Karst. and Larix decidua Mill. in Alpine forests are largely unknown. We investigated the CWD decay dynamics in an Alpine valley in Italy using the chronosequence approach and the five-decay class system that is based on a macromorphological assessment. For the decay classes 1-3, most of the dendrochronological samples were cross-dated to assess the time that had elapsed since tree death, but for decay classes 4 and 5 (poorly preserved tree rings) radiocarbon dating was used. In addition, density, cellulose, and lignin data were measured for the dated CWD. The decay rate constants for spruce and larch were estimated on the basis of the density loss using a single negative exponential model, a regression approach, and the stage-based matrix model. In the decay classes 1-3, the ages of the CWD were similar and varied between 1 and 54 years for spruce and 3 and 40 years for larch, with no significant differences between the classes; classes 1-3 are therefore not indicative of deadwood age. This seems to be due to a time lag between the death of a standing tree and its contact with the soil. We found distinct tree-species-specific differences in decay classes 4 and 5, with larch CWD reaching an average age of 210 years in class 5 and spruce only 77 years. The mean CWD rate constants were estimated to be in the range 0.018 to 0.022 y-1 for spruce and to about 0.012 y-1 for larch. Snapshot sampling (chronosequences) may overestimate the age and mean residence time of CWD. No sampling bias was, however, detectable using the stage-based matrix model. Cellulose and lignin time trends could be derived on the basis of the ages of the CWD. The half-lives for cellulose were 21 years for spruce and 50 years for larch. The half-life of lignin is considerably higher and may be more than

  15. Potencialidad de Prosopis ferox Griseb (Leguminosae, subfamilia: Mimosoideae para estudios dendrocronológicos en desiertos subtropicales de alta montaña Potential of Prosopis ferox Griseb (Leguminosae, subfamily: Mimosoideae for dendrochronological studies in high-montane subtropical deserts

    Directory of Open Access Journals (Sweden)

    MARIANO S. MORALES

    2001-12-01

    Full Text Available Debido a la escasez de especies con anillos anuales de crecimiento, la dendrocronología de regiones áridas de montañas tropicales y subtropicales está muy poco desarrollada. En este trabajo evaluamos el potencial de la especie arbórea Prosopis ferox,"churqui", para estudios dendrocronológicos analizando las características anatómicas del leño y las relaciones entre registros climáticos y cronologías de ancho de anillos de una colección realizada a 3.500 m, en la quebrada de Humahuaca (23°13' S, 65°20' O, Provincia de Jujuy, Argentina. Las observaciones microscópicas de cortes histológicos muestran que los anillos están claramente demarcados por una banda parenquimática terminal clara. Comparando la cronología estandarizada de ancho de anillos con los registros instrumentales de La Quiaca (22º06'S, 65º36'O, se observan correlaciones significativas con precipitaciones por encima de la media y temperaturas por debajo de la media durante los meses de verano (diciembre_marzo. Esto se interpreta como una relación positiva con la disponibilidad de agua en el suelo durante el período de crecimiento. Esta cronología representa no solamente el primer registro dendrocronológico desarrollado a partir de P. ferox, sino también la primera cronología de anillos de árboles en la provincia biogeográfica Prepuneña. La buena discriminación de los anillos anuales de crecimiento, la fuerte relación con variables climáticas, el amplio rango de distribución de la especie en el noroeste de Argentina y sur de Bolivia (20° a 25° S y la longevidad observada en individuos aislados (c. 500 años, hacen de P. ferox una especie muy promisoria para estudios dendroclimatológicos y dendroecológicos en desiertos subtropicales de alta montañaDue to the scarcity of species with annual tree rings, the use of dendrochronological techniques has received little attention in tropical and subtropical montane dry areas. In this study, we assess the

  16. Opportunities and applications of dendrochronology in Africa

    NARCIS (Netherlands)

    Gebrekirstos, A.; Bräuning, A.; Sass-Klaassen, U.; Mbow, C.

    2014-01-01

    Partly due to severe lack of instrumental climate data, the drivers of the African climate, their interactions and impacts are poorly understood. The paper demonstrates the prospects and applications of dendroecological and stable isotope techniques, such as to reconstruct climate variability,

  17. Results of the Dendrochronological Studies in Mongolia

    Directory of Open Access Journals (Sweden)

    Gordon C. Jacoby

    2003-06-01

    Full Text Available The Mongolian-AmericanTree-Ring Project was initiated in 1995 to develop longer climatic records in Mongolia and to help establish capabilities in Mongolia for independent tree-ring analyses. The records from old-aged trees can provide more complete information about the variations in the climate system and aid in planning for future changes or variations in climate. Many areas of Mongolia have been investigated and tree-ring samples collected. Dendroclimatic records of temperature extending back more than one thousand years and precipitation records of over 300 years have been developed. These records show that global warming is present in Mongolia and that variations in precipitation and stream-flow appear to show some solar influence. Scientists and students trained by ,the project are now engaged in tree-ring studies in various areas of Mongolia. The project is expected to continue for the next several years.

  18. Paleo-event data standards for dendrochronology

    Science.gov (United States)

    Elaine Kennedy Sutherland; P. Brewer; W. Gross

    2017-01-01

    Extreme environmental events, such as storm winds, landslides, insect infestations, and wildfire, cause loss of life, resources, and human infrastructure. Disaster riskreduction analysis can be improved with information about past frequency, intensity, and spatial patterns of extreme events. Tree-ring analyses can provide such information: tree rings reflect events as...

  19. Dendrochronology of species from Brazilian Araucaria Forest, Candoi, PR Dendrocronologia de espécies da Floresta Ombrófila Mista do Município de Candói, PR

    Directory of Open Access Journals (Sweden)

    Patricia Póvoa de Mattos

    2010-06-01

    Full Text Available In the present work the dendrochronological potential of six species of the Araucaria Forest is analyzed. The trunks of 20 trees were collected in Candoi, State of Parana, Brazil, from an area that belongs to
    ELEJOR, Centrais Elétricas do Rio Jordão, for the following species: Araucaria angustifolia, Clethra scabra, Cedrela lilloi, Ocotea porosa, Podocarpus lambertii and Sebastiania commersoniana (3 to 6, from each species. The trunks were sawed, and at breast height a sample was taken from the center of the board, from bark to bark, crossing the pith, for macroscopic analysis. These samples were dried and polished, making possible the recognition and measurement of growth rings The historical climatic data series were provided by SIMEPAR, the State weather institute. The trees presented diameter at breast height (DBH, varying from 14 cm to 40 cm, with age of 60 years, annual diameter increment of 0.6 cm, in average. Although the number of trees was small, it was possible to observe that the site was not limiting for the species, as the growth rings showed very low sensitivity.
    However, the very extreme growth condition of 1999 and 2000, when  occurred a very low precipitation period followed by a very severe winter, was registered in the growth ring series of most of the disks analyzedFoi analisado o potencial dendrocronológico de seis espécies da Floresta Ombrófila Mista (FOM.
    Foram coletados troncos em Candói, PR, em uma área pertencente a ELEJOR, Centrais Elétricas do Rio Jordão,
    sendo três a seis indivíduos das espécies: Araucaria angustifolia, Clethra scabra, Cedrela lilloi, Ocotea
    porosa, Podocarpus lambertii e Sebastiania commersoniana. Os troncos foram serrados, sendo retiradas amostras à altura do peito, da prancha central, de casca a casca, cruzando a medula, para análise macroscópica. Essas amostras foram secas e lixadas, possibilitando o reconhecimento e medição dos anéis de crescimento. A

  20. Dendrochronology and bark anatomy of the frankincense tree

    NARCIS (Netherlands)

    Tolera Feyissa, M.

    2013-01-01

    Boswellia papyrifera(Burseraceae) trees grow in drylands south of the Sahara. In Ethiopia, it grows in seasonally dry Combretum-Terminalia woodlands. It is a source of frankincense, an economically important olio-gum resin used for cultural and religious ceremonies throughout

  1. Spatial and temporal analysis of mass movement using dendrochronology

    NARCIS (Netherlands)

    Braam, R.R.; Weiss, E.E.J.; Burrough, P.A.

    1987-01-01

    Tree growth and inclination on sloping land is affected by mass movement. Suitable analysis of tree growth and tree form can therefore provide considerable information on mass movement activity. This paper reports a new, automated method for studying the temporal and spatial aspects of mass

  2. Dendrochronology and late Holocene history of Bering piedmont glacier, Alaska

    Science.gov (United States)

    Wiles, G.C.; Post, A.; Muller, E.H.; Molnia, B.F.

    1999-01-01

    Fluctuations of the piedmont lobe of Bering Glacier and its sublobe Steller Glacier over the past two millennia are reconstructed using 34 radiocarbon dates and tree-ring data from 16 sites across the glaciers' forelands. The general sequence of glacial activity is consistent with well-dated fluctuations of tidewater and land-terminating glaciers elsewhere along the Gulf of Alaska. Extensive forested areas along 25 km of the Bering ice margin were inundated by glacio-lacustrine and glacio-fluvial sediments during a probable ice advance shortly before 500 cal yr A.D. Regrowth of forests followed the retreating ice as early as the 7th century A.D., with frequent interruptions of tree growth due to outwash aggradation. Forests overrun by ice and buried in outwash indicate readvance about 1080 cal yr A.D. Retreat followed, with ice-free conditions maintained along the distal portions of the forefield until the early 17th century after which the ice advanced to within a few kilometers of its outer Neoglacial moraine. Ice reached this position after the mid-17th century and prior to 200 yr ago. Since the early 20th century, glacial retreat has been punctuated by periodic surges. The record from forests overrun by the nonsurging Steller Lobe shows that this western ice margin was advancing by 1250 A.D., reaching near its outer moraine after 1420 cal yr A.D. Since the late 19th century, the lobe has dominantly retreated.

  3. Using dendrochronology to measure radial growth of defoliated trees

    Science.gov (United States)

    Thomas W. Swetnam; Marna Ares Thompson; Elaine Kennedy. Sutherland

    1985-01-01

    Budworms (Choristoneura spp.) have repeatedly defoliated millions of hectares of conifers throughout North America. The seriousness of the problem is underscored by research findings in eastern Canada and the northern U.S. Rocky Mountains that the extent, severity, and frequency of bud worm outbreaks have increased in the 20th century, primarily as a result of human-...

  4. The dendrochronological potential of Baikiaea plurijuga in Zambia

    NARCIS (Netherlands)

    Ngoma, Justine; Speer, James H.; Vinya, Royd; Kruijt, Bart; Moors, Eddy; Leemans, Rik

    2017-01-01

    Climate has been demonstrated to change at different scales for as far back as we have been able to reconstruct it. However, anthropogenic factors have accelerated and are predicted to cause significant changes in temperature and precipitation around the globe. As a consequence, vegetation is

  5. Radiocarbon adjustments to the dendrochronology of a yellowwood tree

    CSIR Research Space (South Africa)

    Vogel, JC

    2001-03-01

    Full Text Available High-precision radiocarbon dating of a millennium-old yellowwood tree from the Midlands of Natal shows that the tree-rings do, in general, record annual growth, but that both missing and false rings occur. At two places along the transect...

  6. Advancing dendrochronological studies of fire in the United States

    Science.gov (United States)

    Grant L. Harley; Christopher H. Baisan; Peter M. Brown; Donald A. Falk; William T. Flatley; Henri D. Grissino-Mayer; Amy Hessl; Emily K. Heyerdahl; Margot W. Kaye; Charles W. Lafon; Ellis Q. Margolis; R. Stockton Maxwell; Adam T. Naito; William J. Platt; Monica T. Rother; Thomas Saladyga; Rosemary L. Sherriff; Lauren A. Stachowiak; Michael C. Stambaugh; Elaine Kennedy Sutherland; Alan H. Taylor

    2018-01-01

    Dendroecology is the science that dates tree rings to their exact calendar year of formation to study processes that influence forest ecology (e.g., Speer 2010 [1], Amoroso et al., 2017 [2]). Reconstruction of past fire regimes is a core application of dendroecology, linking fire history to population dynamics and climate effects on tree growth and survivorship. Since...

  7. Carbon and Oxygen Isotope Dendrochronology in Sub-Fossil Bog Oak Tree Rings - A Preliminary Study

    NARCIS (Netherlands)

    Sass, U.G.W.; Poole, I.; Wils, T.; Helle, G.; Schleser, G.H.; Bergen, van P.

    2005-01-01

    Isotope dendroclimatology is a relatively new field investigating environmental factors that control the radial growth of trees. Tree-ring series of sub-fossil bog oaks can be dated from sites across northwest Europe indicating that the environmental change(s) were regional rather than local. Bog

  8. A dendrochronological study of teak (Tectona grandis L. f., Verbenaceae) in Puerto Rico

    Science.gov (United States)

    Margaret S. Devall; Bernard R. Parresol

    2003-01-01

    In Puerto Rico, an island in the West Indies, large areas of primary forest have been cut and converted to farmland or to secondary forest; subsequently the farmlands declined in fertility and were abandoned. Various tree species were planted in order to restore the degraded land and to provide timber. Teak is a species with great restoration potential in Puerto Rico...

  9. Reconstructing mass balance of Garabashi Glacier (1800–2005 using dendrochronological data

    Directory of Open Access Journals (Sweden)

    E. A. Dolgova

    2013-01-01

    Full Text Available The exploration whether tree-ring data can be effectually applied for the mass balance reconstruction in Caucasus was the main goal of this research. Tree-ring width and maximum density chronologies of pine (Pinus sylvestris L. at seven high-elevation sites in Northern Caucasus were explored for this purpose. As well as in other places of the temperate zone tree- ring width has complex climate signal controlled both temperature and precipitation. Instrumental mass balance records of Garabashi Gglacier started at 1983s. It is well known that Caucasus glaciers intensively retreat in the last decades and according to instrumental data mass balance variations are mostly controlled by the ablation, i.e. summer temperature variations. Maximum density chronology has statistically significant correlation with mass balance due to summer temperature sensitivity and great input of ablation to total mass balance variations. To include in our reconstruction different climatically sensitive parameters, stepwise multiple regression model was used. The strongest relation (r = 0.88; r2 = 0.78; p < 0.05 between two ring-width and one maximum density chronologies was identified. Cross-validation test (r = 0.79; r2 = 0.62; p < 0.05 confirmed model adequacy and it allowed to reconstruct Garabashi Glacier mass balance for 1800–2005ss. Reconstructed and instrumental mass balance values coincide well except the most recent period in 2000s, when the reconstructed mass balance slightly underestimated the real values. However even in this period it remained negative as well as the instrumental records. The bias can be explained by the weak sensitivity of the chronologies to winter precipitation (i.e. accumulation. The tree-ring based mass balance reconstruction was compared with one based on meteorological data (since 1905s. Both reconstructions have good interannual agreement (r = 0.53; p < 0.05 particularly for the period between 1975 and 2005. According to the reconstruction two distinct periods of positive mass balance occurred in 1830s and 1860s. They agree well with early historical data and the tree-ring of moraines of Kashkatash Glacier in Central Caucasus. 

  10. [Dendrochronology of Chinese pine in Mulan-Weichang, Hebei Province: a primary study].

    Science.gov (United States)

    Cui, Ming-xing; He, Xing-yuan; Chen, Wei; Chen, Zhen-ju; Zhou, Chang-hong; Wu, Tao

    2008-11-01

    Dendroclimatic methods were used to investigate the relationships between the growth of Chinese pine (Pinus tabulaeformis Carr.) and the climatic parameters in Mulan-Weichang of Hebei Province. The results showed that Chinese pine presented high sensitivity to climatic changes, and its earlywood width showed the highest sensitivity. There was a significant negative correlation between the tree-ring width chronology of Chinese pine and the air temperature in May-June. The precipitation and relative humidity in June had strong positive effects on the growth of earlywood, the precipitation from September to next September had significant positive effects on Chinese pine growth, and the relative humidity in winter more strongly affected the growth of latewood than of earlywood. There was a definite correlation between the tree-ring width chronology of Chinese pine and the large scale climate fluctuation. From 1951 to 2006, the increase of air temperature in study area was significant, and the sensitivity of Chinese pine to the variations of local temperature and precipitation decreased, presenting an inverse transforming trend with increasing temperature. Greater differences were observed between the reconstructed and observed data of mean temperature in May - June in a century scale, suggesting that the tree-ring growth of Chinese pine in study area had a greater fluctuation of sensitivity to the variation of climatic factors.

  11. Dendrochronological reconstruction of the epicenter and early spread of emerald ash borer in North America

    Science.gov (United States)

    Nathan W. Siegert; Deborah G. McCullough; Andrew M. Liebhold; Frank W. Telewski

    2014-01-01

    Emerald ash borer Agrilus planipennis was identified in 2002 as the cause of extensive ash (Fraxinus spp.) decline and mortality in Detroit, Michigan, and has since killed millions of ash trees in the US and Canada. When discovered, it was not clear how long it had been present or at what location the invading colony started....

  12. Reconstructing the temporal and spatial dynamics of emerald ash borer adults through dendrochronological analyses

    Science.gov (United States)

    Nathan W. Siegert; Deborah G. McCullough; Andrew M. Liebhold; Frank W. Telewski

    2007-01-01

    Emerald ash borer (Agrilus planipennis Fairmaire; Coleoptera: Buprestidae) was identified in June 2002 as the cause of widespread ash (Fraxinus spp.) mortality in southeastern lower Michigan and Windsor, Ontario. Localized outlier populations have since been discovered across much of lower Michigan and in areas of Indiana, Ohio and...

  13. KASHKATASH GLACIER FLUCTUATIONS IN THE XVII–XXI CENTURIES FROM CARTOGRAPHIC, DENDROCHRONOLOGICAL AND LICHENOMETRIC DATA

    Directory of Open Access Journals (Sweden)

    I. S. Bushueva

    2012-01-01

    Full Text Available We focused our study on the retreat of a typical valley glacier Kashkatash, located in the Elbrus Area. We compared the old photographs of the glacier forefields (H. Burmester, 1911; H. Altberg, 1927; E.N. Lukasheva, 1932; unknown author, 1939 with the aerial photograph of 1957, 1965, 1987, maps of scale 1:100 000 (1890 and 1:25 000 (1950s, satellite images (CORONA of 1971, ASTER of 2005, EROS of 2006, oblique photographs taken in 1980s–2000s and plans, created by different researches. Using cartographic material and old photographs we reconstructed 14 positions of glacier tongue over the last 120 years. We estimated the linear glacier retreat and the age of numerous stadial moraines basing on geomorphic, tree-ring and lichenometric data and correlated our results with previous sparse glacier fluctuation reconstructions in this region. We identified at least 13 end moraines within the distance of 900 meters from the up-to-date glacier front position. The minimum age of the outer moraine is 450 years according to the tree-ring data. One tree growing on this moraine was damaged by a boulder falling down from a younger moraine under formation in the period from autumn 1839 to spring 1840. Three moraines were deposited in 1870s–1890s. In 20th century the glacier advanced in 1910-s, 1920-s, and 1970–1980-s.

  14. Using dendrochronology to model hemlock woolly adelgid effects on eastern hemlock growth and vulnerability

    Science.gov (United States)

    James Rentch; Mary Ann Fajvan; Richard Evans; Brad. Onken

    2008-01-01

    This study examined the relationship between eastern hemlock (Tsuga canadensis (L.) Carr.) crown condition and changes in radial growth associated with infestation by hemlock woolly adelgid (HWA), Adelges tsugae (Hemiptera: Adelgidae). Tree-ring chronologies of eastern hemlock were used to develop a binomial decline index based on...

  15. The reconstruction of Lymantria dispar outbreaks by dendrochronological methods in the South Urals

    Science.gov (United States)

    Sergei Kucherov

    1991-01-01

    Interest in investigating the influence of extreme ecological factors on the radial growth of oak (Quercus robur L.) is bound up with oak dieback in the South Urals during the last decade. Factors contributing to this problem in the study area are hard winter frosts, late spring frosts, and Lymantria dispar L. outbreaks. To...

  16. RECONSTRUCTION AND PREDICTION OF WATER BALANCE COMPONENTS FROM DENDROCHRONOLOGICAL DATA FOR THE NARYN RIVER BASIN (KYRGYZSTAN

    Directory of Open Access Journals (Sweden)

    V. G. Konovalov

    2012-01-01

    Full Text Available Suggested new method for reconstruction of runoff includes: 1. Search informative points based weather observations for dependence runoff = f(climate index. Climate index consists of normalized anomalies of annual precipitation and air temperature, together with water vapor pressure and total cloud amount in the June–September. 2. The selection of sites that represent local relationship between the index of climate and tree rings. 3. Getting the multivariate linear regression equation between the runoff V and tree rings D. Basic climatic period 1961–1990 is used as a calibration interval of time. Verification of the equations for 1940–1960 identified the need to use other arguments in addition to the width of tree rings. For this purpose, two climate index: PDSI and SPEI were tested. It is established that the empirical formulae V = f(D, PDSI and V = f(D, SPEI are suitable for assessing the annual flow of the Naryn in 1901–2006. In the report is described a process of  reconstruction of flow for the years 1700–2005 based on the data of the width of the tree rings, and taking into account the temporal variability of parameters of regression equations.Chronologies of the width and density of tree rings in the thirty-two tree ring sites were used to reconstruct long-term series of average summer air temperature Ts at meteorological stations of the Pamir and Tien Shan. The calibration interval of time was 1961–1990 to find equations Ts = f(D of third-order multiple regression, and independent control of their quality, done in 1932–1960. Combined correlation coefficient in 10 cases out of 15 was more than 0.80, a relative error of calculation Ts in 19611990 ranged from 0.13 to 4.73%, and in 1932–1960 from 0.23 to 8.10%. Duration of the reconstructed series Ts ranged from 100 to 278 years. Positive results were received for predicting a common and glacial runoff of Naryn river, a long-term range of density of tree rings. 

  17. USING DENDROCHRONOLOGY TO IDENTIFY MAJOR ICE STORM EVENTS IN OAK FORESTS OF SOUTHWESTERN VIRGINIA. (R825157)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  18. Dendrochronological assessment of drought severity indices for Panola Mountain Research Watershed, Georgia, U.S.A.

    Science.gov (United States)

    McKee, A.; Aulenbach, B. T.

    2015-12-01

    Quantifying the relation between drought severity and tree growth is important to predict future growth rates as climate change effects the frequency and severity of future droughts. Two commonly used metrics of drought severity are the Standardized Precipitation Index (SPI) and the Palmer Drought Severity Index (PDSI). These indices are often calculated from proximal weather station data and therefore may not be very accurate at the local watershed scale. The accuracy of these commonly used measures of drought severity was compared to a recently developed, locally calibrated model of water limitation based on the difference between potential and actual evapotranspiration (ETDIFF). Relative accuracies of the drought indices were assessed on the strength of correlations with a 20-year tree-ring index chronology (1986-2006) developed from 22 loblolly pine (Pinus taeda) trees in water-limited landscape positions at the Panola Mountain Research Watershed (PMRW), a 41-hectare forested watershed located in north-central Georgia. We used SPI and PDSI index values from the weather station located at the Atlanta Airport, approximately 36 kilometers from PMRW. ETDIFF was calculated based on precipitation, temperature, runoff, and solar radiation data collected at PMRW. Annual index values for all three drought indices were calculated as the mean value over the growing season (May to September). All three indices had significant Pearson correlations with the tree-ring index (p = 0.044, 0.007, 0.002 for SPI, PDSI, and ETDIFF, respectively). The ETDIFF method had the strongest correlation (R2 = 0.40) compared to SPI and PDSI results (R2 = 0.19 and 0.32, respectively). Results suggest SPI and PDSI provided a general measure of drought conditions, however, the locally calibrated model of water limitation appears to measure drought severity more accurately. Future studies on the ecological effects of drought may benefit from adopting ETDIFF as a measure of drought severity.

  19. Dendrochronological analysis of white oak growth patterns across a topographic moisture gradient in southern Ohio

    Science.gov (United States)

    Alexander K. Anning; Darrin L. Rubino; Elaine K. Sutherland; Brian C. McCarthy

    2013-01-01

    Moisture availability is a key factor that influences white oak (Quercus alba L.) growth and wood production. In unglaciated eastern North America, available soil moisture varies greatly along topographic and edaphic gradients. This study was aimed at determining the effects of soil moisture variability and macroclimate on white oak growth in mixed-oak forests of...

  20. [Extreme Climatic Events in the Altai Republic According to Dendrochronological Data].

    Science.gov (United States)

    Barinov, V V; Myglan, V S; Nazarov, A N; Vaganov, E A; Agatova, A R; Nepop, R K

    2016-01-01

    The results of dating of extreme climatic events by damage to the anatomical structure and missing tree rings of the Siberian larch in the upper forest boundary of the Altai Republic are given. An analysis of the spatial distribution of the revealed dates over seven plots (Kokcy, Chind, Ak-ha, Jelo, Tute, Tara, and Sukor) allowed us to distinguish the extreme events on interregional (1700, 1783, 1788, 1812, 1814, 1884), regional (1724, 1775, 1784, 1835, 1840, 1847, 1850, 1852, 1854, 1869, 1871, 1910, 1917, 1927, 1938, 1958, 1961), and local (1702, 1736, 1751, 1785, 1842, 1843,1874, 1885, 1886, 1919, 2007, and 2009) scales. It was shown that the events of an interregional scale correspond with the dates of major volcanic eruptions (Grimsvotn, Lakagigar, Etna, Awu, Tambora, Soufriere St. Vinsent, Mayon, and Krakatau volcanos) and extreme climatic events, crop failures, lean years, etc., registered in historical sources.

  1. The Bøle ship, Skien, Norway - Research history, dendrochronology and provenance

    DEFF Research Database (Denmark)

    Daly, Aoife; Nymoen, Pål

    2008-01-01

    The wreck-site at Bøle near Skien was first reported in 1950 during dredging in the river. The Bøle ship is one of the most significant medieval ship-finds in Norway, and the manner of its discovery is referred to as a tragedy in ship archaeology. New investigations at the site in 2004–2006 revea......The wreck-site at Bøle near Skien was first reported in 1950 during dredging in the river. The Bøle ship is one of the most significant medieval ship-finds in Norway, and the manner of its discovery is referred to as a tragedy in ship archaeology. New investigations at the site in 2004...

  2. Constraining recent Shiveluch volcano eruptions (Kamchatka, Russia by means of dendrochronology

    Directory of Open Access Journals (Sweden)

    O. Solomina

    2008-10-01

    Full Text Available Shiveluch (N 56°38´, E 161°19´; elevation: active dome ~2500 m, summit of Old Shiveluch 3283 m is one of the most active volcanoes in Kamchatka. The eruptions of Shiveluch commonly result in major environmental damage caused by debris avalanches, hot pyroclastic flows, tephra falls and lahars. Constraining these events in time and space is important for the understanding and prediction of these natural hazards. The last major eruption of Shiveluch occurred in 2005; earlier ones, dated by instrumental, historical, 14C and tephrochronological methods, occurred in the last millennium around AD 1030, 1430, 1650, 1739, 1790–1810, 1854, 1879–1883, 1897–1898, 1905, 1927–1929, 1944–1950, and 1964. A lava dome has been growing in the 1964 crater since 1980, occasionally producing tephra falls and pyroclastic flows. Several Shiveluch eruptions (~AD 1050, 1650, 1854, 1964 may have been climatically effective and are probably recorded in the Greenland ice cores.

    Previously, most dates for eruptions before AD 1854 were obtained by tephrochronology and constrained by radiocarbon dating with an accuracy of several decades or centuries. In this paper we report tree-ring dates for a recent pyroclastic flow in Baidarnaia valley. Though the wood buried in these deposits is carbonized, fragile and poorly preserved, we were able to measure ring-width using standard tree-ring equipment or photographs and to cross-date these samples against the regional Kamchatka larch ring-width chronology. The dates of the outer rings indicate the date of the eruptions. In the Baidarnaia valley the eruption occurred shortly after AD 1756, but not later than AD 1758. This date coincides with the decrease of ring-width in trees growing near Shiveluch volcano in 1758–1763 in comparison with the control "non-volcanic" chronology. The pyroclastic flow in Kamenskaia valley, although similar in appearance to the one in Baidarnaia valley, definitively yielded a different age. Due to the age limit of the reference chronology (AD 1632–2005 and its short overlap with the sample chronology in Kamenskaia valley the dates of these deposits are very preliminary. The deposits probably date back to approximately AD 1649 or a few years later. This date is in close agreement with the previously obtained radiocarbon date of these sediments to AD 1641(16521663. Our data agree well with the tephrochronological findings, and further constrain the chronology of volcanic events in this remote area.

  3. Dendrochronology of two butternut (Juglans cinerea) populations in the southeastern United States

    Science.gov (United States)

    Stacy Clark; Sunshine Brosi; Scott Schlarbaum; Henri Grissino-Mayer

    2008-01-01

    Butternut (Juglans cinerea) has been an important component of eastern hardwood forests in North America since the last ice-age, but an exotic fungal pathogen (Sirococcus clavigignenti-juglandacearum) has been devastating the species throughout its native range since the late 1960s. Restoration strategies have not been widely adopted in the southern part of the species...

  4. The Karschau ship, Schleswig-Holstein: Dendrochronological results and timber provenance

    DEFF Research Database (Denmark)

    Daly, Aoife

    2007-01-01

    The felling of the oak trees used to build the Karschau ship took place in or around the AD 1140s. The tree-ring curves from the oak planks from the Karschau Ship match best with site-means from Odense, a medieval town on the island of Funen, Denmark. New research being carried out by the author ...

  5. Non-invasive dendrochronology of late-medieval objects in Oslo

    DEFF Research Database (Denmark)

    Daly, Aoife; Streeton, Noëlle L.W.

    2017-01-01

    scanner. For these reasons, a combined approach was adopted, utilizing CT scanning where possible, but preceded by an ‘exposed-wood’ imaging technique. Both non-invasive techniques have yielded reliable results, and CT scanning has confirmed the reliability of the imaging technique alone. This paper...... presents the analytical methods, along with results from two of the 13 objects under investigation. Results for reliable dates and provenances provide new foundations for historical interpretations....

  6. A dendrochronology based fire history of Jeffry pine-mixed conifer forests in the Sierra San Pedro Martir, Mexico

    Science.gov (United States)

    Scott L. Stephens; Carl N. Skinner; Samantha J. Gill

    2003-01-01

    Conifer forests in northwestern Mexico have not experienced systematic fire suppression or logging, making them unique in western North America. Fire regimes of Pinus jeffreyi Grev. & Balf. mixed conifer forests in the Sierra San Pedro Martir, Baja California, Mexico, were determined by identifying 105 fire dates from 1034 fire scars in 105 specimens. Fires were...

  7. Drought-triggered western spruce budworm outbreaks in the Interior Pacific Northwest: A multi-century dendrochronological record

    Science.gov (United States)

    A. Flower; D. G. Gavin; E. K. Heyerdahl; R. A. Parsons; G. M. Cohn

    2014-01-01

    Douglas-fir forests in the interior Pacific Northwest are subject to sporadic outbreaks of the western spruce budworm, a species widely recognized as the most destructive defoliator in western North America. Outbreaks of the western spruce budworm often occur synchronously over broad regions and lead to widespread loss of leaf area and decrease in growth rates in...

  8. Dendrochronological research in an artificially established sessile oak stand in the area of Fruška Gora

    Directory of Open Access Journals (Sweden)

    Stajić Branko

    2014-01-01

    Full Text Available This paper presents the first regional research of the chronologies of sessile oak trees and definition of the local (master chronology of sessile oak in the area of Fruška Gora. In addition, the aim of this study is to determine the strength of the common signal in the growth of sessile oak and its dendroclimatological potential under the given conditions. The quality of the local series of radial increment (chronology and the strength of the common and climatic signals were evaluated using the following parameters: average mean sensitivity, expressed population signal, signal-to-noise ratio and the variance explained by eigenvectors in the procedure of analysis of the principal components. The results have shown that the obtained master chronologies are of satisfactory quality and reliability, and that they contain a sufficient general common ”signal”, which is a characteristic of all analyzed trees that can be processed in all dendroclimatological analyses. It was concluded that, under the investigated site conditions, sessile oak showed low to medium sensitivity of reaction to the modifications of environmental conditions in the past 90 years. [Projekat Ministarstva nauke Republike Srbije: Šumski zasadi u funkciji povećanja pošumljenosti Srbije

  9. A dendrochronological analysis of a disturbance-succession model for oak-pine forests of the Appalachian Mountains, USA

    Science.gov (United States)

    Patrick H. Brose; Thomas A. Waldrop

    2010-01-01

    Disturbance-succession models describe the relationship between the disturbance regime and the dominant tree species of a forest type. Such models are useful tools in ecosystem management and restoration, provided they are accurate. We tested a disturbance-succession model for the oak-pine (Quercus spp. - Pinus spp.) forests of the...

  10. Tree-Rings, Timbers and Trees: A dendrochronological survey of the 14th-century cog, Doel 1

    DEFF Research Database (Denmark)

    Haneca, Kristof; Daly, Aoife

    2014-01-01

    In 2000, the remains of a cog, Doel 1, were found in Doel, Belgium. Wood species identification of all ship timbers and smaller elements was performed. European oak was the dominant species, followed by alder that was used for the fairings. In total 150 ring-width series were recorded. The constr......In 2000, the remains of a cog, Doel 1, were found in Doel, Belgium. Wood species identification of all ship timbers and smaller elements was performed. European oak was the dominant species, followed by alder that was used for the fairings. In total 150 ring-width series were recorded...

  11. Radiocarbon dating for tree rings of dendro-chronologically dated Japan cedars buried in the paddy field at Fukui

    International Nuclear Information System (INIS)

    Shibata, S.; Kawano, E.; Kimura, K.; Mine, T.; Harada, M.

    1999-01-01

    14 C dating of 6 Japan cedars having the relative growing ages were made. On the basis of correlation analysis of our data to a 14 C age data set, INTCAL of CALIB (Stuiver), the growing ages of these Japan cedars were estimated (BC 1090-2375). The atmospheric 14 C concentration (Δ 14 C) at their growing ages were obtained from the 14 C age data. The variation of Δ 14 C shows basically the same pattern with that of Europe or America (r=0.783). (author)

  12. 76 FR 14060 - Notice of Inventory Completion: U.S. Department of the Interior, Bureau of Indian Affairs...

    Science.gov (United States)

    2011-03-15

    ... rooms, 10 grinding bins, a tower, and toeholds), archeological context, dendrochronology, and a physical... on architectural features (cliff dwelling), archeological context, dendrochronology, and a physical...

  13. The 14C record in bristlecone pine wood of the past 8000 years based on the dendrochronology of the late C.W. Ferguson

    International Nuclear Information System (INIS)

    Suess, H.E.; Linick, T.W.

    1990-01-01

    When, in 1950, Willard Libby and his coworkers obtained their first radiocarbon ( 14 C) dates, C W Ferguson at the University of Arizona Tree Ring Laboratory was working on establishing a continuous tree ring series for the newly discovered bristlecone pine Pinus aristata. Before his untimely death in 1986, he had extended the series nearly 8000 years into the past. From the Ferguson series I obtained for 14 C determinations wood samples grown at various times. Also, two other laboratories obtained such samples. For B.C. times in particular, our measured 14 C-values that deviated consistently from those calculated from tree rings, and the deviations increased with age. This general trend was observed by other laboratories, but the presence of deviations from these trends, of the so-called 'wiggles', was questioned by other workers. To me these wiggles indicated the existence of a most interesting geophysical parameter valid for the whole terrestrial atmosphere. Fourier spectra obtained at my request by Kruse in 1972, and by Neftel, demonstrated the consistency of the results, and supported my contention that the secular variations of 14 C in atmospheric CO 2 are related to variations of solar activity. (author)

  14. DENDROCHRONOLOGY of ABIES NORDMANNIANA (STEV. SPACH. SUBSP. NORDMANNIANA IN THE ÖRÜMCEK FORESTS IN KÜRTÜN-GÜMÜSHANE

    Directory of Open Access Journals (Sweden)

    Zafer Cemal Özkan

    2003-04-01

    Full Text Available Abies nordmanniana (Stev. Spach. subsp. nordmanniana Dogu Karadeniz Bölgesi için olduğu kadar Türkiye için de önemli bir orman ağacıdır. Çalışmanın amacı; Doğu Karadeniz Göknarı ağaçlarının yıllık büyüme ve değişimleri araştırıp, incelemek ve yıllık halkalardan yararlanarak Örümcek Bölgesi Ormanlarında göknar için ortalama yıllık halka eğrisi ve standart kronoloji hazırlamaktır. Aynı zamanda yörenin eteorolojik verileri de kullanılarak geçmiş yılların iklimi hakkında bilgi edinebilmek amacıyla yapılacak olan dendroklimatoloji çalışmalarına esas oluşturacaktır. Araştırma alanı Karadeniz Bölgesinin, Doğu Karadeniz Bölümünde yer almakta, Gümüşhane ili, Kürtün ilçesi sınırları içerisinde kalmaktadır. Toplam 6 ağaçtan 12 kalem alınmıştır ve elde edilen kalemlerdeki yıllık halka genişliklerinin ölçümünde 0.01 mm. duyarlı Zeiss Winkel aleti kullanılmıştır. Yıllık halka eğrilerinin elde edilmesinde ; 1 Yıllık Halkaların Yarı Logaritmik Olarak Gösterilmesi, 2 Yıllık Halkalardan Elde Edilen İndislerin Bir Grafikle Gösterilmesi (Standardizasyon yöntemleri kullanılmıştır. İndis değerlerinin bulunmasında ise It=Wt/Yt eşitliğinden yararlanılmıştır. Çalışma 1729 –2003 yıllarını kapsamaktadır.

  15. Western spruce budworm outbreaks did not increase fire risk over the last three centuries: A dendrochronological analysis of inter-disturbance synergism

    Science.gov (United States)

    Aquila Flower; Daniel G. Gavin; Emily K. Heyerdahl; Russell A. Parsons; Gregory M. Cohn

    2014-01-01

    Insect outbreaks are often assumed to increase the severity or probability of fire occurrence through increased fuel availability, while fires may in turn alter susceptibility of forests to subsequent insect outbreaks through changes in the spatial distribution of suitable host trees. However, little is actually known about the potential synergisms between these...

  16. An Investigation of the Relationship Between Tritium in Groundwater and the Dendrochronology of Tritium in Trees at the Savannah River Site. Final report

    International Nuclear Information System (INIS)

    Murphy, C.E. Jr.; Kalin, R.M.

    1995-01-01

    This project was supported through ERDA to demonstrate that the temporal distribution of tritium can be documented by the analysis of bound hydrogen in annual tree-ring samples. The project focuses on two sample locations at the Savannah River Site (SRS), a nuclear material production facility located in Aiken, SC. The SRS provided samples of cross-sections from a single tree that were to be pooled together for analysis. Annual tree-rings were identified in each cross-section sample and separated for the period 1954 to 1993. These annual samples were ground and chemically treated to separate the hollocellulose fraction of the wood, then subsequently combusted and the resulting water counting using low-level liquid scintillation counting equipment. Additionally, the ground annual tree-rings were gamma-counted to determine any temporal variation in radionuclide activity and analyzed with x-ray fluorescence to find any temporal variation in trace-element concentrations. This report presents the results and is intended to be a compilation of the work

  17. The Basque farmhouses of Zelaa and Maiz Goena : New dendrochronology-based findings about the evolution of the built heritage in the northern Iberian Peninsula

    NARCIS (Netherlands)

    Susperregi, J.; Telleria, I.; Urteaga, M.; Jansma, E.

    2017-01-01

    The Basque farmhouse, a characteristic building type for north-western Spain, is an architectural solution that allows the combined management of different rural activities. In addition to providing living quarters and a space for a cider press these farmhouses were designed to function as, among

  18. Holocene tree-line variability in the Kauner Valley, Central Eastern Alps, indicated by dendrochronological analysis of living trees and subfossil logs

    NARCIS (Netherlands)

    Nicolussi, Kurt; Kaufmann, Matthias; Patzelt, Gernot; van der Plicht, Johannes; Thurner, Andrea

    2005-01-01

    The altitude of the Alpine tree-line has often been used as proxy for the climatic conditions in the Holocene epoch. The usual approach for establishing a record for this proxy is the analysis of pollen and macro remains. We analysed living trees and subfossil logs from the timberline ecotone in the

  19. Using dendrochronology to detect and attribute CO2-induced growth increases in P. menziesii and P. ponderosa in western North America

    Science.gov (United States)

    Stretch, V.; Gedalof, Z.; Berg, A. A.

    2010-12-01

    Increased atmospheric CO2 could increase photosynthetic rates and cause trees to use water more efficiently, thereby increasing overall growth rates relative to climatic limiting factors. CO2 fertilization has been found across a range of forest types; however results have been inconsistent and based on short-term studies. Long-term studies based on tree-rings have generally been restricted to a few sites and have produced conflicting results. An initial global analysis of tree-ring widths for evidence of increasing growth relative to drought suggested a small but highly significant proportion of trees exhibit increasing growth over the past 130 years. These growth increases could not be attributed to increasing water use efficiency, elevation effects, nitrogen deposition, or divergence. These results suggest that CO2 fertilization is occurring at some locations and may influence future forest dynamics but this does not appear to occur at all locations. The processes causing differential responses are the focus of this study. Here we illustrate response differences between Douglas-fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa). Using multiple site chronologies from these species over western North America, we demonstrate several site-specific explanations for differential responses to CO2 fertilization, such as forest composition, density, slope, aspect, soil type, and position relative to range limits.

  20. Dendrochronological records of the floodplain morphology transformation of Desná river valley in the last 150 years, The Hrubý Jeseník Mts., Czech Republic

    Czech Academy of Sciences Publication Activity Database

    Hrádek, Mojmír

    2007-01-01

    Roč. 15, č. 3 (2007), s. 2-15 ISSN 1210-8812 R&D Projects: GA AV ČR IAA300860601 Institutional research plan: CEZ:AV0Z30860518 Keywords : floodplain morphology * palaeochannels * historical floods * tree ring reductions * abrupt growth release * exposed roots Subject RIV: DE - Earth Magnetism, Geodesy, Geography

  1. The DCCD: a digital data infrastructure for tree-ring research

    NARCIS (Netherlands)

    Jansma, E.; Lanen, R.J. van; Brewer, P.; Kramer, R. de

    2012-01-01

    Existing on-line databases for dendrochronology are not flexible in terms of user permissions, tree-ring data formats, metadata administration and language. This is why we developed the Digital Collaboratory for Cultural Dendrochronology (DCCD). This TRiDaS-based multi-lingual database allows users

  2. Dendropedagogy: Teaching Botany, Ecology and Statistical Principles through Tree-Ring Studies.

    Science.gov (United States)

    Rubino, Darrin L.; McCarthy, Brian C.

    2002-01-01

    Develops a simple tree-ring laboratory to demonstrate the basics of dendrochronology. Provides two upper-level laboratory exercises primarily intended to demonstrate the specific dendrochronology subdisciplines of dendroclimatology and dendroecology. Suggests using the exercises separately or in unison as part of a multidisciplinary capstone…

  3. Reconstrucción espacial y temporal de la ocurrencia de avalanchas de nieve en los Andes patagónicos utilizando técnicas dendrocronológicas Dendrochronological reconstruction of spatial and temporal patterns of snow avalanches in the Patagonian Andes

    Directory of Open Access Journals (Sweden)

    ALEJANDRO CASTELLER

    2009-06-01

    Full Text Available Las avalanchas de nieve representan un importante riesgo natural en diversas regiones montañosas alrededor del mundo. Daños a infraestructura y pérdidas de vidas humanas son reportados frecuentemente en relación a eventos catastróficos de avalanchas. En los Andes, numerosas obras de infraestructura se ubican en zonas vecinas a senderos de avalanchas, de las que poco se conoce sobre sus alcances máximos, periodos de retorno y presiones de impacto. A través de la implementación de técnicas dendrocronológicas hemos reconstruido las fechas de ocurrencia y áreas de influencia de eventos pasados de avalanchas de nieve. Ejemplares de Nothofagus pumilio con perturbaciones visibles de avalanchas fueron muestreados en sectores del canal, bordes y zonas de frenado de 11 senderos de avalanchas ubicados en Loma de las Pizarras, próximo a El Chaltén, Santa Cruz, Argentina. Además, áreas de control fueron muestreadas para determinar las condiciones de crecimiento en árboles no afectados por avalanchas. Nuestros análisis indican que las cicatrices, las variaciones de excentricidad en el leño, los cambios abruptos de crecimiento y la presencia de leño de tensión son los principales indicadores dendrocronológicos en N. pumilio asociados a la ocurrencia de avalanchas. Basados en una ponderación cuantitativa de los indicadores y en la profundidad de muestreo, calculamos un índice de ocurrencia de eventos, el cual nos permitió determinar para cada sendero los años con ocurrencia de avalanchas. Considerando de manera integral la actividad de avalanchas en los 11 senderos muestreados, los años con mayor ocurrencia de eventos fueron 1936, 1966, 1978 y 1995. Complementariamente, registros climáticos fueron analizados con el objetivo de determinar las relaciones entre los años con ocurrencia de avalanchas y las variaciones mensuales de precipitación y temperatura. Se observa que los años con gran frecuencia de avalanchas están significativamente correlacionados con la ocurrencia de abundantes precipitaciones invernales; no se detectaron relaciones significativas con las variaciones de temperatura. Los resultados alcanzados en esta investigación prueban el potencial dendrocronológico de N. pumilio para reconstruir patrones espaciales y temporales de avalanchas de nieve en los Andes patagónicos.

  4. Trees, astronomy, ruins and isotopes

    International Nuclear Information System (INIS)

    Thwaites, R.N.

    1985-01-01

    The history of dendrochronology is traced from the discovery of the method to prove astronomic sun-spot cycles to its use in archaeology for dating purposes. The principles and problems of both dendrochronology and radiocarbon 14 C dating are described and the subsequent relationship of the two sciences in aiding the calibration of absolute dating methods using carbon isotopes is explained. The development of graphic calibration, which introduces a seemingly erratic curve, is discussed as regards its validity for accurate dating up to 50 000 years B.P. Whilst dendrochronology continues in other spheres as a science in its own right, the polemics surrounding valid radiocarbon calibration remain

  5. The development of high precision 14C measurement and its application to archaeological time-scale problems

    International Nuclear Information System (INIS)

    Pearson, G.W.

    1983-01-01

    High precision calibration curve of some 6000 years has been constructed from the measurement of contiguous 20 year samples of dendrochronologically dated Irish oak. 14 C evidence was presented using a 'wiggle' matching technique which supported the dendrochronological fixing of the BC period Irish oak chronology. Two archaeological samples were 'wiggle matched' to give a calendar age within a range of 25 years and proved that this technique is as precise as dendrochronological dating and is potentially as useful for a much wider range of samples and growth periods. (author)

  6. Proceedings of the fire history workshop; October 20-24, 1980; Tucson, Arizona

    Science.gov (United States)

    Marvin A. Stokes; John H. Dieterich

    1980-01-01

    The purpose of the workshop was to exchange information on sampling procedures, research methodologies, preparation and interpretation of specimen material, terminology, and the application and significance of findings, emphasizing the relationship of dendrochronology procedures to fire history interpretations.

  7. Krovy z pomezí jižních Čech a Moravy inspirované úspornými návrhy Michaela Ranka

    Czech Academy of Sciences Publication Activity Database

    Bláha, Jiří

    2010-01-01

    Roč. 17, č. 1 (2010), s. 67-82 ISSN 1212-1487 Institutional research plan: CEZ:AV0Z20710524 Keywords : timber roofs * carpenter * dendrochronology Subject RIV: AL - Art, Architecture, Cultural Heritage www.pruzkumypamatek.cz

  8. Can a fake fir tell the truth about Swiss needle cast? (paper)

    Science.gov (United States)

    A key question in dendrochronology to reconstruct forest disturbance history is how to distinguish between the effects of Swiss needle cast (SNC) and other forest disturbance agents (e.g., Arceuthobium spp., Armillaria, Phaseolus schweinitzii, Dendroctonus ponderosae, Dendroctonu...

  9. A multi-proxy perspective on millennium-long climate variability in the Southern Pyrenees

    NARCIS (Netherlands)

    Morellón, M.; Pérez-Sanz, A.; Corella, J.P.; Büntgen, U.; Catalán, J.; González-Samprizé, P.; González-Trueba, J.J.; López-Sáez, J.A.; Moreno, A.; Pla-Rabes, S.; Saz-Sánchez, M.Á.; Scussolini, P.; Serrano, E.; Steinhilber, F.; Stefanova, V.; Vegas-Vilarrúbia, T.; Valero-Garcés, B.

    2012-01-01

    This paper reviews multi-proxy paleoclimatic reconstructions with robust age-control derived from lacustrine, dendrochronological and geomorphological records and characterizes the main environmental changes that occurred in the Southern Pyrenees during the last millennium. Warmer and relatively

  10. Northern European summer temperature variations over the Common Era from integrated tree-ring density records

    Czech Academy of Sciences Publication Activity Database

    Esper, J.; Düthorn, E.; Krusic, P. J.; Timonen, M.; Büntgen, Ulf

    2014-01-01

    Roč. 29, č. 5 (2014), s. 487-494 ISSN 0267-8179 Institutional support: RVO:67179843 Keywords : dendrochronology * Finland * late holocene * Sweden * temperature reconstruction Subject RIV: EH - Ecology, Behaviour Impact factor: 3.357, year: 2014

  11. The investigation of solar activity signals by analyzing of tree ring chronological scales

    Science.gov (United States)

    Nickiforov, M. G.

    2017-07-01

    The present study examines the ability of detecting short-cycles and global minima of solar activity by analyzing dendrochronologies. Starting with the study of Douglass, which was devoted to the question of climatic cycles and the growth of trees, it is believed that the analysis of dendrochronologies allows to detect the cycle of Wolf-Schwabe. According to his results, the cycle was absent during Maunder's minimum and appeared after its completion. Having checked Douglass's conclusions by using 10 dendrochronologies of yellow pines from Arizona, which cover the time period from 1600 to 1900, we have come to the opposite results. The verification shows that: a) none of the considered dendroscale allows to detect an 11-year cycle; 2) the behaviour of a short peroid-signal does not undergo significant changes before, during or after Maunder's minimum. A similar attempt to detect global minima of solar activity by using five dendrochronologies from different areas has not led to positive results. On the one hand, the signal of global extremum is not always recorded in dendrochronology, on the other hand, the deep depression of annual rings allows to suppose the existence of a global minimum of solar activity, which is actually absent.

  12. Study of long-time variations of cosmic rays

    International Nuclear Information System (INIS)

    Dergachev, V.A.

    1979-01-01

    Discussed are some problems of the investigation into the cosmic rays intensity in the past via the contents of cosmogenic isotopes in the samples of known age, mainly measuring the activity of radiocarbon in the samples dated by the dendrochronological method. The necessity of production of the multicentury dendrochronological scales with absolute dating for decoding of the information contained in the annual rings during the large time scale is pointed out. The dendrochronologic studies supplemented by the radiocarbon dating would permit to study the variations in radiocarbon content and to determine the factors, which influence this content, during large time intervals. The different factors - the solar activity, the supernovae flares et cetera - influencing the radiocarbon concentration are considered

  13. Element analysis and radioactivity measurement within a wood disk by neutron activation analysis

    International Nuclear Information System (INIS)

    Hayashi, Y.; Ikeue, N.; Tanoi, K.; Tange, T.; Yagi, H.; Nakanishi, T.M.

    2003-01-01

    16 elements and the radioactivity of 210 Pb in a wood disk, across the annual rings have been analyzed to find out a promising tool for dendrochronology (chronology of wood) both for a Japanese wood, Cryptomeria japonica, and for an Indonesian rain forest wood, Alstonia, which does not form annual rings because of the relatively constant climate of the rain forest. As a result, only Mg concentration showed similar, smooth decreasing tendency in both wood species. The smooth change of the Mg concentration across the annual rings along with the growth suggested the possibility of the Mg concentration determination as a promising dendrochronological tool. (author)

  14. The scientific dating of standing buildings.

    Science.gov (United States)

    Alcock, Nathaniel W

    2017-11-17

    The techniques of dendrochronology (tree-ring dating) and radiocarbon (14C) dating are described, as they are applied to historic buildings. Both rely on determining the felling dates of the trees used in their construction. For dendrochronology, the construction of master chronologies and the matching of individual ring-width sequences to them is described and, for radiocarbon dating, the use of tree-ring results in calibration. Results of dating are discussed, ranging from the cathedrals of Peterborough and Beauvais and the development of crown-post roof structures, to the dating and identification of standing medieval peasant houses, particularly those built using cruck construction.

  15. Eneolithic pile dwellings south of the Alps precisely dated with tree-ring chronologies from the north

    OpenAIRE

    Čufar, Katarina; Tegel, Willy; Merela, Maks; Kromer, Bernd; Velušček, Anton

    2016-01-01

    We present dendrochronological dating of Eneolithic pile dwellings on Ljubljansko barje, Slovenia, from the 4th millennium BC, partly included on the UNESCO world heritage list in 2011. Samples of oak (Quercus sp.) timbers from the posts on which the dwellings were built have been collected over the past 20 years. They have been dendrochronologically cross-dated and (pre) dated by 14C wiggle-matching. We describe the construction of a 442-year chronology BAR-3330 based on 106 cross-dated tree...

  16. Exkurz dendrochronologie krovů kostela sv. Kunhuty v Kostelci u Jihlavy

    Czech Academy of Sciences Publication Activity Database

    Kyncl, Tomáš

    2001-01-01

    Roč. 8, č. 1 (2001), s. 118-121 ISSN 1212-1487 R&D Projects: GA ČR GA205/98/1542; GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z6005908 Keywords : dendrochronological dating Subject RIV: EF - Botanics

  17. Population dynamics and clonal growth of Spartocytisus supranubius (Fabaceae), a dominant shrub in the alpine zone of Tenerife, Canary Islands

    Czech Academy of Sciences Publication Activity Database

    Kyncl, Tomáš; Suda, J.; Wild, Jan; Wildová, Radka; Herben, Tomáš

    2006-01-01

    Roč. 186, - (2006), s. 97-108 ISSN 1385-0237 R&D Projects: GA ČR(CZ) GA206/00/1445 Institutional research plan: CEZ:AV0Z60050516 Keywords : dendrochronology * isozymes * population projection matrix Subject RIV: EF - Botanics Impact factor: 1.383, year: 2006

  18. Canopy accession patterns of table mountain and pitch pines during the 19th and 20th centuries

    Science.gov (United States)

    Patrick H. Brose; Thomas A. Waldrop

    2012-01-01

    A dendrochronology study was conducted in three upland yellow pine stands in Georgia to determine whether the individual Table Mountain (Pinus pungens) and pitch (P. rigida) pines originated in sunny gaps or shaded understories, whether they grew uninterrupted into the canopy or were assisted by one or more releases, and whether...

  19. Results of lichenometric dating of masonry in the outskirts of Kandalaksha city (Russia, Murmansk region

    Directory of Open Access Journals (Sweden)

    Melekhin Alexey

    2014-11-01

    Full Text Available The lichenometric dating of masonry in the area of Kandalaksha city was carried out. For more accurate dating, the reference sites with known age (70 years were laid in Pechenga district (Murmansk region. According to our calculations, the age of masonry was in the range of 60 to 80 years, that is consistent with dendrochronology data (75 years.

  20. The Courtrai chest from New College, Oxford, re-examined

    International Nuclear Information System (INIS)

    Hall, E.T.

    1987-01-01

    The paper concerns the age estimation of the Courtrai chest from New College Oxford, using the accelerator mass spectrometer method. Radiocarbon dating of the wood in the chest revealed a date around 1280, which is in agreement with dates determined using the dendrochronological technique. (UK)

  1. Nové poznatky ke stavebnímu vývoji kostela sv. Jana Křtitele v Kurdějově

    Czech Academy of Sciences Publication Activity Database

    Bláha, Jiří; Dohnalová, P.

    2013-01-01

    Roč. 20, č. 1 (2013), s. 237-256 ISSN 1212-1487 R&D Projects: GA MK(CZ) DF11P01OVV002 Keywords : fortified church * timber roof * dendrochronology Subject RIV: AL - Art, Architecture, Cultural Heritage www.pruzkumypamatek.cz

  2. Establishment patterns of water-elm at Catahoula Lake, Louisiana

    Science.gov (United States)

    Karen S. Doerr; Sanjeev Joshi; Richard F. Keim

    2015-01-01

    At Catahoula Lake in central Louisiana, an internationally important lake for water fowl, hydrologic alterations to the surrounding rivers and the lake itself have led to an expansion of water-elm (Planera aquatic J.F. Gmel.) into the lake bed. In this study, we used dendrochronology and aerial photography to quantify the expansion of water-elm in the lake and identify...

  3. Möglichkeiten und Grenzen für eine Rekonstruktion der "Ersten" Brücke von Mikulčice (Tschechische Republik)

    Czech Academy of Sciences Publication Activity Database

    Poláček, Lumír; Wilke, G.

    2014-01-01

    Roč. 55, č. 2 (2014), s. 37-59 ISSN 1211-7250 R&D Projects: GA ČR(CZ) GAP405/11/2258 Keywords : Mikulčice * river distributaries * bridge * bridge construction * bay configuration * reconstruction of bridges * archaeology * dendrochronology Subject RIV: AC - Archeology, Anthropology, Ethnology

  4. Results of radiocarbon dating of Holocene fluvial sediments from Northeastern Bohemia

    International Nuclear Information System (INIS)

    Silar, J.; Zeman, A.

    1989-01-01

    Samples of wood and charcoal from the latest Holocene fluvial sediments under the lowest surface of alluvial plains were dated by radiocarbon in order to check paleomagnetic data at four sites in northeastern Bohemia. The results are presented as funcorrected 14 C ages and dendrochronologically corrected ages. Two samples were recent. 4 figs., 1 tab., 3 refs

  5. The ''Amsterdam Castle'': A case study of wiggle matching and the proper calibration curve

    NARCIS (Netherlands)

    van der Plicht, J; Jansma, E|info:eu-repo/dai/nl/074965255; Kars, H

    1995-01-01

    We have performed a high-precision 14C wiggle-matching study on two oak beams from the "Castle of Amsterdam". These beams are also dated by dendrochronology. Our two dating methods can only be made consistent using the recommended calibration curve (1986) instead of the revised one (1993).

  6. Crossdating Juniperus procera from North Gondar, Ethiopia

    NARCIS (Netherlands)

    Wils, T.; Robertson, I.; Eshetu, Z.; Touchan, R.; Sass-Klaassen, U.; Koprowski, M.

    2011-01-01

    The application of dendrochronology in (sub)tropical regions has been limited by the difficulty in finding trees with distinct annual rings that can be crossdated. Here, we report successful crossdating of Juniperus procera trees from North Gondar, Ethiopia. The trees form annual rings in response

  7. Macroanatomy and compartmentalization of recent fire scars in three North American conifers

    Science.gov (United States)

    Kevin T. Smith; Estelle Arbellay; Donald A. Falk; Elaine Kennedy Sutherland

    2016-01-01

    Fire scars are initiated by cambial necrosis caused by localized lethal heating of the tree stem. Scars develop as part of the linked survival processes of compartmentalization and wound closure. The position of scars within dated tree ring series is the basis for dendrochronological reconstruction of fire history. Macroanatomical features were described for western...

  8. Timber–regionality and temporality in Northern Europe’s shipbuilding resource

    DEFF Research Database (Denmark)

    Daly, Aoife Maeliosa

    2017-01-01

    of communication growing and changing through time. An even greater wealth of tree-ring data, for oak in Northern Europe, from our terrestrial built heritage provides the tool which we use for dating and locating the source of ships’ timbers. I am beginning to tap into this dendrochronological resource, through...

  9. A multi-century analysis of disturbance dynamics in pine-oak forests of the Missouri Ozark Highlands

    Science.gov (United States)

    Chad King; Rose-Marie. Muzika

    2013-01-01

    Using dendrochronology and growth release approaches, we analyzed the disturbance history of shortleaf pine (Pinus echinata Mich.) white oak (Quercus alba L.) forests in the Missouri Ozark Highlands. The objectives of this study were to (1) identify growth release events using living and remnant shortleaf pine and white oak, (2)...

  10. Global Change. Teaching Activities on Global Change for Grades 4-6.

    Science.gov (United States)

    Geological Survey (Dept. of Interior), Reston, VA.

    This packet contains a series of teaching guides on global change. The series includes lessons on dendrochronology; land, air, and water; and island living. Included is information such as : laws of straws; where land, air, and water meet; and Earth as home. Each section provides an introductory description of the activity, the purpose of the…

  11. Can a fake fir tell the truth about Swiss needle cast?

    Science.gov (United States)

    A key question in dendrochronology to reconstruct forest disturbance history is how to distinguish between the effects of Swiss needle cast (SNC) and other forest disturbance agents (e.g., Douglas-fir beetle, tussock moth, western spruce budworm, laminated root rot, Armillaria ro...

  12. Zpráva o odběru vzorků ze subfosilních kmenů pro dendrochronologickou analýzu v povodí řeky Moravy

    Czech Academy of Sciences Publication Activity Database

    Dvorská, Jitka; Janál, Jiří; Škojec, Jaroslav

    2001-01-01

    Roč. 43, - (2001), s. 323-324 ISSN 1211-7250 R&D Projects: GA ČR(CZ) GP404/01/P127 Institutional research plan: CEZ:AV0Z8001916 Keywords : Morava river basin * dendrochronology * subfosil trunks Subject RIV: AC - Archeology, Anthropology, Ethnology

  13. Setting a date

    International Nuclear Information System (INIS)

    Moore, Glenis.

    1987-01-01

    Dating techniques are discussed and explained. The age range and sensitivity of different techniques are given. Potassium/argon dating, amino-acid dating, radiocarbon dating, dendrochronology, thermoluminescence and geomagnetic field dating are all mentioned. Each technique is explained and a brief history given. The techniques and equipment used by the British Museum, and some examples of archaeological articles dated are mentioned. (UK)

  14. Annual rings in a native Hawaiian tree, Sophora chrysophylla, on Maunakea, Hawai‘i

    Science.gov (United States)

    Kainana S. Francisco; Patrick J. Hart; Jinbao Li; Edward R. Cook; Patrick J. Baker

    2015-01-01

    Annual rings are not commonly produced in tropical trees because they grow in a relatively aseasonal environment. However, in the subalpine zones of Hawai‘i's highest volcanoes, there is often strong seasonal variability in temperature and rainfall. Using classical dendrochronological methods, annual growth rings were shown to occur in Sophora...

  15. Growth-climate relationships across topographic gradients in the northern Great Lakes

    Science.gov (United States)

    S.F. Dymond; A.W. D' Amato; Randy Kolka; P.V. Bolstad; Stephen Sebestyen; J.B. Bradford

    2016-01-01

    Climatic conditions exert important control over the growth, productivity, and distribution of forests, and characterizing these relationships is essential for understanding how forest ecosystems will respond to climate change. We used dendrochronological methods to develop climate–growth relationships for two dominant species, Populus tremuloides...

  16. Missing Rings, Synchronous Growth, and Ecological Disturbance in a 36-Year Pitch Pine (Pinus rigida) Provenance Study

    Science.gov (United States)

    Caroline Leland; John Hom; Nicholas Skowronski; F. Thomas Ledig; Paul J. Krusic; Edward R. Cook; Dario Martin-Benito; Javier Martin-Fernandez; Neil Pederson; Dusan Gomory

    2016-01-01

    Provenance studies are an increasingly important analog for understanding how trees adapted to particular climatic conditions might respond to climate change. Dendrochronological analysis can illuminate differences among trees from different seed sources in terms of absolute annual growth and sensitivity to external growth factors. We analyzed annual radial growth of...

  17. Archaeology and science

    International Nuclear Information System (INIS)

    1980-01-01

    The purpose of the conference was to bring together archaelogists and scientists to discuss cooperation, especially in the fields of isotope (C14) dating, thermolumescence dating and dendrochronology. In addition to texts of papers presented, summaries of the discussions and the formal proposals for future activities are given. (JIW)

  18. Time-dependent effects of climate and drought on tree growth in a Neotropical dry forest: Short-term tolerance vs. long-term sensitivity

    NARCIS (Netherlands)

    Mendivelso, H.A.; Camarero, J.J.; Gutierrez, E.; Zuidema, P.

    2014-01-01

    We analyzed the effects of climate and drought on radial growth using dendrochronology in seven deciduous tree species coexisting in a Bolivian tropical dry forest subjected to seasonal drought. Precipitation, temperature and a multiscalar drought index were related to tree-ring width data at

  19. Markers inside wood : tree rings as archives of insect outbreaks, drift-sand dynamics, and spring flooding

    NARCIS (Netherlands)

    Copini, P.

    2015-01-01

    MARKERS INSIDE WOOD – TREE RINGS AS ARCHIVES OF INSECT OUTBREAKS, DRIFT-SAND DYNAMICS AND SPRING FLOODING

    Trees are long-living organisms that record ecologically relevant information in their xylem that can be accessed by dendrochronology, the study of tree rings. Specific environmental

  20. Krovy hřbitovního kostela sv. Michaela v Poličce

    Czech Academy of Sciences Publication Activity Database

    Bláha, Jiří

    2017-01-01

    Roč. 24, č. 2 (2017), s. 61-69 ISSN 1212-1487 R&D Projects: GA MŠk(CZ) LO1219 Keywords : timber frame * roof * church * carpentry * dendrochronology Subject RIV: AL - Art, Architecture, Cultural Heritage OBOR OECD: Architecture engineering http://www.pruzkumypamatek.cz/casopis-4-1.php?ID=2017-02-07

  1. Zur Entwicklung der Grenze im mährisch-österreichischen Grenzgebiet während des 11.–12. Jahrhunderts und zur Rolle der Befestigung von Nikolsburg/Mikulov

    Czech Academy of Sciences Publication Activity Database

    Balcárková, A.; Kalhous, David; Eichert, S.

    2017-01-01

    Roč. 32, č. 2016 (2017), s. 37-72 ISSN 1011-0062 R&D Projects: GA ČR GA15-22658S Keywords : Late Hillford period * pottery * borders * dendrochronology * castles Subject RIV: AC - Archeology, Anthropology, Ethnology OBOR OECD: Archaeology

  2. Breaking new ground at the interface of dendroecology and mycology.

    Science.gov (United States)

    Büntgen, Ulf; Egli, Simon

    2014-10-01

    New insight on the mycorrhizal fungus-host association, expected to emerge from combining dendrochronology, wood anatomy and mycology, may help to understanding better and disentangle biotic, abiotic, and combined edaphic factors of the mutualistic relation between ectomycorrhizal fungi and their perennial partners. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Increased spruce tree growth in Central Europe since 1960s

    Czech Academy of Sciences Publication Activity Database

    Cienciala, E.; Altman, Jan; Doležal, Jiří; Kopáček, Jiří; Štěpánek, Petr; Stähl, G.; Tumajer, J.

    2018-01-01

    Roč. 619, 1 apr (2018), s. 1637-1647 ISSN 0048-9697 R&D Projects: GA ČR(CZ) GA14-12262S Institutional support: RVO:67985939 ; RVO:60077344 ; RVO:67179843 Keywords : Picea abies * Stem increment * Dendrochronology Subject RIV: EH - Ecology, Behaviour OBOR OECD: Ecology Impact factor: 4.900, year: 2016

  4. Recent climate warming forces contrasting growth responses of white spruce at treeline in Alaska through temperature thresholds

    Science.gov (United States)

    Martin Wilmking; Glenn P. Juday; Valerie A. Barber; Harold S.J. Zald

    2004-01-01

    Northern and high-latitude alpine treelines are generally thought to be limited by available warmth. Most studies of tree-growth-climate interaction at treeline as well as climate reconstructions using dendrochronology report positive growth response of treeline trees to warmer temperatures. However, population-wide responses of treeline trees to climate remain largely...

  5. Establishment and growth of hawthorn in floodplains in the Netherlands

    NARCIS (Netherlands)

    Decuyper, M.; Cornelissen, P.; Sass, U.G.W.

    2014-01-01

    Dendrochronology was used to assess the influence of soil conditions, elevation and related inundation, climate fluctuations and vegetation cover on the establishment and growth of hawthorn in non-grazed river floodplains. Presence of forest influences the discharge capacity of the floodplain,

  6. Dendroarchaeology: Successes in the past - challenges for the future

    NARCIS (Netherlands)

    Sass-Klaassen, U.

    2002-01-01

    This article summarises the most important topics that were discussed during the Archaeology session in the ¿Tree Rings and People¿ conference in Davos, Switzerland. Main topics are the relation between the archaeologists and dendrochronologists and the future perspectives of dendrochronology in the

  7. Subfossil bog-pine horizons document climate and ecosystem changes during the Mid-Holocene

    NARCIS (Netherlands)

    Eckstein, J.; Leuschner, H.H.; Bauerochse, A.; Sass-Klaassen, U.

    2009-01-01

    Extended dendrochronological investigations were performed on subfossil pine entombed in peat layers of former raised bogs in Lower Saxony (NW Germany). The aim was to study of dynamics in bog development in response to local environmental conditions and regional changes in climate throughout the

  8. Vývoj moravsko-rakouské hranice v raném středověku. Mikulov - vstupní brána na území Moravy

    Czech Academy of Sciences Publication Activity Database

    Balcárková, A.; Kalhous, David

    2016-01-01

    Roč. 107, prosinec (2016), s. 117-180 ISSN 0031-0506 R&D Projects: GA ČR GA15-22658S Keywords : Early Middle Ages * Late Hillfort period * pottery * borders * dendrochronology Subject RIV: AC - Archeology, Anthropology, Ethnology

  9. Dendroecological applications in air pollution and environmental chemistry: research needs

    Science.gov (United States)

    Samuel B. McLaughlin; Walter C. Shortle; Kevin T. Smith

    2002-01-01

    During the past two decades, dendrochronology has evolved in new dimensions that have helped address both the extent and causes of impacts of regional scale environmental pollution on the productivity and function of forest ecosystems. Initial focus on the magnitude and timing of alterations of baseline growth levels of individual forest trees has now broadened to...

  10. Terminology and biology of fire scars in selected central hardwoods

    Science.gov (United States)

    Kevin T. Smith; Elaine Kennedy Sutherland

    2001-01-01

    Dendrochronological analysis of fire scars requires tree survival of fire exposure. Trees survive fire exposure by: (1) avoidance of injury through constitutive protection and (2) induced defense. Induced defenses include (a) compartmentalization processes that resist the spread of injury and infection and (b) closure processes that restore the continuity of the...

  11. Dating raised bogs : New aspects of AMS C-14 wiggle matching, a reservoir effect and climatic change

    NARCIS (Netherlands)

    Kilian, MR; VanDerPlicht, J; VanGeel, B; Geel, B. van

    1995-01-01

    High resolution AMS dating of Holocene raised bog deposits (Engbertsdijksvenen, The Netherlands) shows natural C-14 variations (wiggles) which can be matched with the dendrochronological calibration curve. Comparison of our results with other, conventionally dated peat cores and the Delta(14)C

  12. Validation of annual growth rings in freshwater mussel shells using cross dating .Can

    Science.gov (United States)

    Andrew L. Rypel; Wendell R. Haag; Robert H. Findlay

    2009-01-01

    We examined the usefulness of dendrochronological cross-dating methods for studying long-term, interannual growth patterns in freshwater mussels, including validation of annual shell ring formation. Using 13 species from three rivers, we measured increment widths between putative annual rings on shell thin sections and then removed age-related variation by...

  13. Application of Raman spectroscopy to analyse lignin/cellulose ratio in Norway spruce tree rings

    Czech Academy of Sciences Publication Activity Database

    Vítek, Petr; Klem, Karel; Urban, Otmar

    2017-01-01

    Roč. 20, 1-2 (2017), s. 41-48 ISSN 1803-2451 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : dendrochronology * vibrational spectroscopy * lignification * Norway spruce * abiotic stress Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany

  14. Divergent growth of Norway spruce on Babia Góra Mountain in the western Carpathians

    NARCIS (Netherlands)

    Buras, Allan; Spyt, Barbara; Janecka, Karolina; Kaczka, Ryszard

    2018-01-01

    Growth divergence – i.e. the expression of divergent growth trends of neighboring trees – has certain implications for dendrochronological research, for instance in the context of climate reconstructions but also in terms of estimating net ecosystem productivity. Thus, understanding the underlying

  15. New tree-ring evidence for the Late Glacial period from the northern pre-Alps in eastern Switzerland

    Czech Academy of Sciences Publication Activity Database

    Reinig, F.; Nievergelt, D.; Esper, J.; Friedrich, M.; Helle, G.; Hellmann, L.; Kromer, B.; Morganti, S.; Pauly, M.; Sookdeo, A.; Tegel, W.; Treydte, K.; Verstege, A.; Wacker, L.; Büntgen, Ulf

    2018-01-01

    Roč. 186, APR (2018), s. 215-224 ISSN 0277-3791 Keywords : new-zealand kauri * laacher see volcano * ice-core records * radiocarbon calibration * central-europe * cal bp * southern-hemisphere * last deglaciation * hohenheim oak * climate * Central Europe * Dendrochronology * Late Glacial * Paleoclimatology * Radiocarbon * Subfossil wood * Switzerland * Tree rings * Younger Dryas Impact factor: 4.797, year: 2016

  16. Age estimation of large trees: New method based on partial increment core tested on an example of veteran oaks

    Czech Academy of Sciences Publication Activity Database

    Altman, Jan; Doležal, Jiří; Čížek, Lukáš

    2016-01-01

    Roč. 380, č. 11 (2016), s. 82-89 ISSN 0378-1127 R&D Projects: GA ČR(CZ) GA14-12262S; GA ČR GAP504/12/1952 Institutional support: RVO:67985939 ; RVO:60077344 Keywords : Tree age estimation * Dendrochronology * Partial cores Subject RIV: EH - Ecology, Behaviour Impact factor: 3.064, year: 2016

  17. European dendrochronoloy and C-14 dating of timber

    International Nuclear Information System (INIS)

    Fletcher, J.M.

    1975-01-01

    An account is given of the development of dendrochronology and C-14 dating in Europe. Corrections to raw C-14 dates, sampling and the uncertainty of C-14 ages of wood, and correlation of dates obtained by the two methods, are discussed. (U.K.)

  18. Emerald ash borer biology and invasion history

    Science.gov (United States)

    Robert A. Haack; Yuri Baranchikov; Leah S. Bauer; Therese M. Poland

    2015-01-01

    The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is native to eastern Asia and is primarily a pest of ash (Fraxinus) trees (Fig. 1). Established populations of EAB were first detected in the United States and Canada in 2002 (Haack et al., 2002), and based on a dendrochronology study by Siegert...

  19. A power-driven increment borer for sampling high-density tropical wood

    Czech Academy of Sciences Publication Activity Database

    Krottenthaler, S.; Pitsch, P.; Helle, G.; Locosselli, G. M.; Ceccantini, G.; Altman, Jan; Svoboda, M.; Doležal, Jiří; Schleser, G.; Anhuf, D.

    2015-01-01

    Roč. 36, November (2015), s. 40-44 ISSN 1125-7865 R&D Projects: GA ČR GAP504/12/1952; GA ČR(CZ) GA14-12262S Institutional support: RVO:67985939 Keywords : tropical dendrochronology * tree sampling methods * increment cores Subject RIV: EF - Botanics Impact factor: 2.107, year: 2015

  20. The Mollö Cog Re-Examined and Re-Evaluated

    DEFF Research Database (Denmark)

    Von Arbin, Staffan; Daly, Aoife

    2012-01-01

    As part of a research project on medieval trade and maritime transportation in the former Norwegian province of Bohuslän, western Sweden, a dendrochronological analysis of the so-called Mollö cog was undertaken. The wreck, which was first salvaged in 1980, was previously dated by 14 C analysis...

  1. TRiCYCLE: a universal conversion tool for digital tree-ring data

    NARCIS (Netherlands)

    Brewer, P.; Murphy, D.; Jansma, E.

    2011-01-01

    There are at least 21 dendro-data formats used in dendrochronology laboratories around the world. Many of these formats are read by a limited number of programs, thereby inhibiting collaboration, limiting critical review of analyses, and risking the long-term accessibility of datasets. Some of the

  2. Calibration of the 14C timescale over the past 30,000 years using mass spectrometric U-Th ages from Barbados corals

    International Nuclear Information System (INIS)

    Bard, E.; Hamelin, B.; Fairbanks, R.G.; Zindler, A.

    1990-01-01

    Uranium-thorium ages obtained by mass spectrometry from corals raised off the island of Barbados confirm the high precision of this technique over at least the past 30,000 years. Comparison of the U-Th ages with 14 C ages obtained on the Holocene samples shows that the U-Th ages are accurate, because they accord with the dendrochronological calibration. Before 9,000 yr BP the 14 C ages are systematically younger than the U-Th ages, with a maximum difference of ∼3,500 yr at ∼20,000 yr BP. The U-Th technique thus provides a way of calibrating the radiocarbon timescale beyond the range of dendrochronological calibration. (author)

  3. Olive tree-ring problematic dating: a comparative analysis on Santorini (Greece.

    Directory of Open Access Journals (Sweden)

    Paolo Cherubini

    Full Text Available Olive trees are a classic component of Mediterranean environments and some of them are known historically to be very old. In order to evaluate the possibility to use olive tree-rings for dendrochronology, we examined by various methods the reliability of olive tree-rings identification. Dendrochronological analyses of olive trees growing on the Aegean island Santorini (Greece show that the determination of the number of tree-rings is impossible because of intra-annual wood density fluctuations, variability in tree-ring boundary structure, and restriction of its cambial activity to shifting sectors of the circumference, causing the tree-ring sequences along radii of the same cross section to differ.

  4. Olive tree-ring problematic dating: a comparative analysis on Santorini (Greece).

    Science.gov (United States)

    Cherubini, Paolo; Humbel, Turi; Beeckman, Hans; Gärtner, Holger; Mannes, David; Pearson, Charlotte; Schoch, Werner; Tognetti, Roberto; Lev-Yadun, Simcha

    2013-01-01

    Olive trees are a classic component of Mediterranean environments and some of them are known historically to be very old. In order to evaluate the possibility to use olive tree-rings for dendrochronology, we examined by various methods the reliability of olive tree-rings identification. Dendrochronological analyses of olive trees growing on the Aegean island Santorini (Greece) show that the determination of the number of tree-rings is impossible because of intra-annual wood density fluctuations, variability in tree-ring boundary structure, and restriction of its cambial activity to shifting sectors of the circumference, causing the tree-ring sequences along radii of the same cross section to differ.

  5. Structural diagnosis of historic timber structures: the Diplomatic Room of the of Royal Palace of Naples

    Directory of Open Access Journals (Sweden)

    Donato Calicchio

    2012-12-01

    Full Text Available The aim of this article is to describe the diagnosis process made on the timber structure that holds up the vault of the Diplomatic Room of the Royal Palace in Naples (Italy. After a brief historical description of the Royal Palace and the Diplomatic Room, it discusses the methodology according to Italian regulations and the speci­fic problems that arose during the works. To complete the diagnosis, a dendrochronological analysis of the wooden elements was performed. The results show the residual mechanical properties of each structural element and the main problems to be resolved by the restorers. The dendrochronological conclusions yield that the dating of the elements is compatible with that of the frescoes on the vault and therefore demonstrate that the elements have not been replaced.

  6. Radiocarbon calibration - past, present and future

    Energy Technology Data Exchange (ETDEWEB)

    Plicht, J. van der E-mail: plicht@phys.rug.nl

    2004-08-01

    Calibration of the Radiocarbon timescale is traditionally based on tree-rings dated by dendrochronology. At present, the tree-ring curve dates back to about 9900 BC. Beyond this limit, marine datasets extend the present calibration curve INTCAL98 to about 15 600 years ago. Since 1998, a wealth of AMS measurements became available, covering the complete {sup 14}C dating range. No calibration curve can presently be recommended for the older part of the dating range until discrepancies are resolved.

  7. The radiocarbon timescale

    International Nuclear Information System (INIS)

    Mook, W.G.

    1977-01-01

    The relation between the conventional 14 C timescale and the astronomical timescale is of increasing importance and interest. A concise review is given of the calibrations which have been carried out thus far on dendrochronologically dated tree rings. The causes of the discrepancies between both scales are briefly indicated. The reliability of the existing calibration curves, the problems which are encountered in using them and the necessity of further calibration measurements are discussed. (author)

  8. Neutron activation analysis of absolutely-dated tree rings

    International Nuclear Information System (INIS)

    Uenlue, K.; Hauck, D.K.; Kuniholm, P.I.; Chiment, J.J.

    2005-01-01

    Gold concentration was determined for dendrochronologically-dated wood samples using neutron activation analysis (NAA) and correlation sought with known environmental changes, e.g., volcanic activities, during historic periods. Uptake of gold is sensitive to soil pH for many plants. Data presented are from a single, cross-dated tree that grew in Greece. Using NAA, gold was measured with parts-per-billion sensitivity in individual tree rings from 1411 to 1988 AD. (author)

  9. Radiocarbon measurements on submerged forest floating chronologies

    International Nuclear Information System (INIS)

    Campbell, J.A.; Baxter, M.S.

    1979-01-01

    It is stated that the submerged forests along the west coast of England and Wales provide a unique source of wood for radiocarbon/ dendrochronological studies. 14 C age determinations are reported on sequential growth increments from three 'gloating' chronologies. A sampling frequency of approximately 10 samples per century was used. Fluctuations in atmospheric 14 C levels of 2 to 3% over several decades can occur, these variations being superimposed on a smoothly changing trend. (author)

  10. Radiocarbon calibration - past, present and future

    International Nuclear Information System (INIS)

    Plicht, J. van der

    2004-01-01

    Calibration of the Radiocarbon timescale is traditionally based on tree-rings dated by dendrochronology. At present, the tree-ring curve dates back to about 9900 BC. Beyond this limit, marine datasets extend the present calibration curve INTCAL98 to about 15 600 years ago. Since 1998, a wealth of AMS measurements became available, covering the complete 14 C dating range. No calibration curve can presently be recommended for the older part of the dating range until discrepancies are resolved

  11. Insight into the Fulnek Church and Parish Medieval Building Chronology

    Directory of Open Access Journals (Sweden)

    Augustinková Lucie

    2017-06-01

    Full Text Available The church of the Holy Trinity and parish in Fulnek was for nearly four centuries an Augustinian canonry and collegiate church (1293-1389. The medieval church and parish building chronology, however, have not been thus far established. From research between 2015 and 2016 we have been able to identify medieval portions of the buildings, clarify the site medieval construction phases and date the parish buildings (formerly the canonry from dendrochronological analysis of embedded wooden scaffolding.

  12. Statistical modelling and RCS detrending methods provide similar estimates of long-term trend in radial growth of common beech in north-eastern France

    OpenAIRE

    Bontemps , Jean-Daniel; Esper , Jan

    2011-01-01

    International audience; Dendrochronological methods have greatly contributed to the documentation of past long-term trends in forest growth. These methods primarily focus on the high-frequency signals of tree ring chronologies. They require the removal of the ageing trend in tree growth, known as 'standardisation' or 'detrending', as a prerequisite to the estimation of such trends. Because the approach is sequential, it may however absorb part of the low-frequency historical signal. In this s...

  13. Evaluating the robustness of three ring-width measurement methods for growth release reconstruction

    Czech Academy of Sciences Publication Activity Database

    Maes, S. L.; Vannoppen, A.; Altman, Jan; Van den Bulcke, J.; Decocq, G.; De Mil, T.; Depauw, L.; Landuyt, D.; Perring, M. P.; Van Acker, J.; Vanhellemont, M.; Verheyen, K.

    2017-01-01

    Roč. 46, DEC 2017 (2017), s. 67-76 ISSN 1125-7865 R&D Projects: GA ČR(CZ) GA17-07378S; GA ČR(CZ) GA14-12262S Institutional support: RVO:67985939 Keywords : Dendrochronology * Growth release * Ring-width measurement Subject RIV: EH - Ecology, Behaviour OBOR OECD: Ecology Impact factor: 2.259, year: 2016

  14. UPDATING THE CZECH MILLENNIA-LONG OAK TREE-RING WIDTH CHRONOLOGY

    Czech Academy of Sciences Publication Activity Database

    Prokop, O.; Kolář, Tomáš; Kyncl, T.; Rybníček, Michal

    2017-01-01

    Roč. 73, č. 1 (2017), s. 47-52 ISSN 1536-1098 R&D Projects: GA ČR GA13-04291S; GA ČR(CZ) GA17-22102S; GA MŠk(CZ) LO1415 Institutional support: RVO:86652079 Keywords : Belfry construction * Czech Republic * dendrochronology * Quercus * sapwood rings Subject RIV: GK - Forestry OBOR OECD: Forestry Impact factor: 1.769, year: 2016

  15. Increasing moisture limitation of Norway spruce in Central Europe revealed by forward modelling of tree growth in tree-ring network

    Czech Academy of Sciences Publication Activity Database

    Tumajer, J.; Altman, Jan; Štěpánek, Petr; Treml, V.; Doležal, Jiří; Cienciala, E.

    2017-01-01

    Roč. 247, 15 December 2017 (2017), s. 56-64 ISSN 0168-1923 R&D Projects: GA ČR(CZ) GA14-12262S Institutional support: RVO:67985939 ; RVO:67179843 Keywords : Climate change * Dendrochronology * Drought Subject RIV: EH - Ecology, Behaviour; EH - Ecology, Behaviour (UEK-B) OBOR OECD: Ecology; Ecology (UEK-B) Impact factor: 3.887, year: 2016

  16. Increasing Drought Sensitivity and Decline of Atlas Cedar (Cedrus atlantica) in the Moroccan Middle Atlas Forests

    OpenAIRE

    Linares, Juan C.; Taïqui, Lahcen; Camarero, Jesús Julio

    2011-01-01

    An understanding of the interactions between climate change and forest structure on tree growth are needed for decision making in forest conservation and management. In this paper, we investigated the relative contribution of tree features and stand structure on Atlas cedar (Cedrus atlantica) radial growth in forests that have experienced heavy grazing and logging in the past. Dendrochronological methods were applied to quantify patterns in basal-area increment and drought sensitivity of Atla...

  17. Die Quellbecken des eisenzeitlichen Befestigungsareals auf dem Berg Vladař in Westböhmen

    Czech Academy of Sciences Publication Activity Database

    Chytráček, Miloslav; Pokorný, P.; Danielisová, Alžběta; Kyncl, T.

    2012-01-01

    Roč. 90, 1-2 (2012), s. 27-67 ISSN 0016-8874 Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR(CZ) M300020903 Program:M Institutional support: RVO:67985912 Keywords : Early Iron Age * ring forts * fortifications * radiocarbon dating * cisterns * dendrochronology * pollen analyses Subject RIV: AC - Archeology, Anthropology, Ethnology

  18. DETERMINAÇÃO DA ÉPOCA DE DESBASTE PELA ANÁLISE DENDROCRONOLÓGICA E MORFOMÉTRICA DE Ocotea porosa (Nees & Mart. Barroso EM POVOAMENTO NÃO MANEJADO

    Directory of Open Access Journals (Sweden)

    Andreia Taborda dos Santos

    2015-01-01

    Full Text Available Commercial plantations of Ocotea porosa available for studying are scarce and therefore should be used as a source of information to establish the potential for management of the species in plantations, even if these evaluations were not been held along the stand development. The recovery of the historical growth of these stands to optimize the management plans is possible by dendrochronology and by the analysis of morphometric and dendrometric data. The aim of this study was to use stand analysis tools, combined with the dendrochronological studies, to recover and to systematize the development of unmanaged stands. The study was conducted in an unmanaged stand of Ocotea porosa , with with 44 years of age in Rio Negro, PR state, in a UFPR research station. Growth inferences recovered by dendrochronology and the competition by the application of methodologies such as rate of coverage and crown cover rate showed consistent results in the analysis of population, indicating the need for a first thinning near 12 years old. Due to the small number of sampled trees, the results do not allow any definitive generalization. However, they are consistent to establish an analysis protocol for unmanaged stands of Ocotea porosa or other species.

  19. Landslide activity as a threat to infrastructure in river valleys - An example from outer Western Carpathians (Poland)

    Science.gov (United States)

    Łuszczyńska, Katarzyna; Wistuba, Małgorzata; Malik, Ireneusz

    2017-11-01

    Intensive development of the area of Polish Carpathians increases the scale of landslide risk. Thus detecting landslide hazards and risks became important issue for spatial planning in the area. We applied dendrochronological methods and GIS analysis for better understanding of landslide activity and related hazards in the test area (3,75 km2): Salomonka valley and nearby slopes in the Beskid Żywiecki Mts., Outer Western Carpathians, southern Poland. We applied eccentricity index of radial growth of trees to date past landslide events. Dendrochronological results allowed us to determine the mean frequency of landsliding at each sampling point which were next interpolated into a map of landslide hazard. In total we took samples at 46 points. In each point we sampled 3 coniferous trees. Landslide hazard map shows a medium (23 sampling points) and low (20 sampling points) level of landslide activity for most of the area. The highest level of activity was recorded for the largest landslide. Results of the dendrochronological study suggest that all landslides reaching downslope to Salomonka valley floor are active. LiDAR-based analysis of relief shows that there is an active coupling between those landslides and river channel. Thus channel damming and formation of an episodic lake are probable. The hazard of flooding valley floor upstream of active landslides should be included in the local spatial planning system and crisis management system.

  20. Southwestern (U.S.A. Archaeological Tree-Ring Dating: 1930-1942

    Directory of Open Access Journals (Sweden)

    Stephen E. Nash

    1997-11-01

    Full Text Available Dendrochronology, the science of assigning precise and accurate calendar dates to annual growth rings in trees (Stokes and Smiley 1968, was the first independent dating technique available to prehistorians. Ar­chaeological tree-ring dating came of age at a time when North American archaeologists concerned them­selves primarily with time/space systematics (Willey and Sabloff 1980 and yet had no absolute and inde­pendent dating techniques available to guide their analyses. Histories of archaeology typically have not considered the development of archaeological tree-ring dating in detail. Willey and Sabloff (1980:12 devote one paragraph to the development of Southwestern archaeological tree-ring dating, as does Steibing (1993:261. Trigger (1989:305 considers dendrochronology (in the sense of the Douglass method only in light of radiocarbon dating. Textbooks and regional histories of archaeology do a little better in their treat­ment of dendrochronology, though discussions typically focus on the interpretation of tree-ring dates and not on the developmental history of the technique itself (e.g. Cordell 1984:88-90; Fagan 1991:129-133; Lyon 1996:46; Michels 1973:116; Thomas 1979:190-194. Scott (1966:9 argues that 'the story of the discovery of archaeological tree-ring dating by A E. Douglass and others has been told and retold and is now familiar to scientists and laymen alike'. I beg to differ.

  1. Recent widespread tree growth decline despite increasing atmospheric CO2.

    Science.gov (United States)

    Silva, Lucas C R; Anand, Madhur; Leithead, Mark D

    2010-07-21

    The synergetic effects of recent rising atmospheric CO(2) and temperature are expected to favor tree growth in boreal and temperate forests. However, recent dendrochronological studies have shown site-specific unprecedented growth enhancements or declines. The question of whether either of these trends is caused by changes in the atmosphere remains unanswered because dendrochronology alone has not been able to clarify the physiological basis of such trends. Here we combined standard dendrochronological methods with carbon isotopic analysis to investigate whether atmospheric changes enhanced water use efficiency (WUE) and growth of two deciduous and two coniferous tree species along a 9 degrees latitudinal gradient across temperate and boreal forests in Ontario, Canada. Our results show that although trees have had around 53% increases in WUE over the past century, growth decline (measured as a decrease in basal area increment--BAI) has been the prevalent response in recent decades irrespective of species identity and latitude. Since the 1950s, tree BAI was predominantly negatively correlated with warmer climates and/or positively correlated with precipitation, suggesting warming induced water stress. However, where growth declines were not explained by climate, WUE and BAI were linearly and positively correlated, showing that declines are not always attributable to warming induced stress and additional stressors may exist. Our results show an unexpected widespread tree growth decline in temperate and boreal forests due to warming induced stress but are also suggestive of additional stressors. Rising atmospheric CO2 levels during the past century resulted in consistent increases in water use efficiency, but this did not prevent growth decline. These findings challenge current predictions of increasing terrestrial carbon stocks under climate change scenarios.

  2. Oak tree-ring chronologies - an instrument to estimate Carpathians role to separate climate influence in Northern Romania

    Science.gov (United States)

    Constantin, Nechita; Ionel, Popa; Francisca, Chiriloaei

    2017-04-01

    Actual climate conditions are in permanent changes and trees can provide information on the magnitude of current modifications compared with the past. Through dendrochronological methods we have analyzed a network composed of 17 chronologies belonging to the Quercus genus to highlight the role of macro-climate induced by the major landforms in printing a specific growth response pattern to climate. The transect is located in North Romania following a straight line of about 400 km length, crossing the Carpathian Arch. The aim of this study is to highlight the areas with homogenous response of trees to the climatic factors. This fact is important for building long dendrochronological series considering that it is appreciated reduced scale applicability. It is known that in the study area covered with oak-trees the number of long series used for climate reconstructions is reduced. The material used is represented by the dendrochronological series which were sampled according to the standards accepted by the scientific literature. The statistical methods used consist in employing PCA analysis to highlight the spatial segregation, related to PC1 scores. Also hierarchical cluster analysis (HCA) was applied in order to group the series with common features on basis of similarities/dissimilarities. The Euclidian distance between the chronologies was calculated and sampled areas were grouped according to Ward minimum variance method. In addition we performed a redundancy analysis (RDA) which the ordination of the axes it is a linear combination of supplied environmental variables. The correlation analysis with climate factors was accomplished by using bootstrap correlation. The pointer year analysis (the selection criteria is PC1 scores <-0.5) was also performed. The results were related to the postglacial recolonization routes obtained by analyzing the chloroplast DNA.

  3. Tree rings and time: recent historical studies in England

    Directory of Open Access Journals (Sweden)

    Martin Bridge

    2000-11-01

    Full Text Available By studying the annual growth rings of long-lived trees, and those preserved in ancient timbers that have survived in waterlogged or very dry conditions, it is possible to date past events in calendar years and to investigate climatic and other environmental changes. Dendrochronology has many applications, including the dating of buildings and ships and the calibration of the radiocarbon timescale that is so widely used in archaeology. Here the technique is outlined and some recent applications of it in England are described.

  4. Make a date with a tree

    International Nuclear Information System (INIS)

    Baillie, M.; Pilcher, J.

    1988-01-01

    The paper concerns the use of dendrochronology to check the accuracy of radiocarbon dating. The Belfast chronology is described - this involves wood samples precisely dated by tree ring analysis and analysed by high-precision radiocarbon analysis. The analysis resulted in the first continuous high-precision calibration of the radiocarbon time-scale, and confirmed the relationship between radiocarbon dates and tree-ring dates. The use of radiocarbon dating to reveal the age of wood samples that have too few rings to produce an accurate date, is also outlined. (U.K.)

  5. AMS analyses at ANSTO

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, E.M. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia). Physics Division

    1998-03-01

    The major use of ANTARES is Accelerator Mass Spectrometry (AMS) with {sup 14}C being the most commonly analysed radioisotope - presently about 35 % of the available beam time on ANTARES is used for {sup 14}C measurements. The accelerator measurements are supported by, and dependent on, a strong sample preparation section. The ANTARES AMS facility supports a wide range of investigations into fields such as global climate change, ice cores, oceanography, dendrochronology, anthropology, and classical and Australian archaeology. Described here are some examples of the ways in which AMS has been applied to support research into the archaeology, prehistory and culture of this continent`s indigenous Aboriginal peoples. (author)

  6. Magnitude of 14C/12C variations based on archaeological samples

    International Nuclear Information System (INIS)

    Kusumgar, S.; Agrawal, D.P.

    1977-01-01

    The magnitude of 14 C/ 12 C variations in the period A.D. 5O0 to 200 B.C. and 370 B.C. to 2900 B.C. is discussed. The 14 C dates of well-dated archaeological samples from India and Egypt do not show any significant divergence from the historical ages. On the other hand, the corrections based on dendrochronological samples show marked deviations for the same time period. A plea is, therefore, made to study old tree samples from Anatolia and Irish bogs and archaeological samples from west Asia to arrive at a more realistic calibration curve. (author)

  7. The genetic algorithm for a signal enhancement

    International Nuclear Information System (INIS)

    Karimova, L.; Kuadykov, E.; Makarenko, N.

    2004-01-01

    The paper is devoted to the problem of time series enhancement, which is based on the analysis of local regularity. The model construction using this analysis does not require any a priori assumption on the structure of the noise and the functional relationship between original signal and noise. The signal itself may be nowhere differentiable with rapidly varying local regularity, what is overcome with the help of the new technique of increasing the local Hoelder regularity of the signal under research. A new signal with prescribed regularity is constructed using the genetic algorithm. This approach is applied to enhancement of time series in the paleoclimatology, solar physics, dendrochronology, meteorology and hydrology

  8. Long-term variations of cosmic ray intensity

    International Nuclear Information System (INIS)

    Dergachev, V.A.; Kocharov, G.E.; Ostryakov, V.M.

    1982-01-01

    At the present time we know only one possibility to reconstruct the Cosmic Ray intensity in the past. This possibility is connected with the measurements of radiocarbon abundance in the dendrochronologically dated wood samples. As the experiments carried out with the help of spacecrafts, balloons and ground apparatus show the Galactic Cosmic Ray flux essentially varies on a short time scales. The variations are caused by different astrophysical and geophysical phenomena. 14 C isotope allows us to investigate these reasons on a more long time interval in comparison with direct observational possibilities

  9. Klimatska pogojenost debelinskega prirastka dreves ob slovenskih visokogorskih alpskih jezerih = Climatic conditioning or radial increments of trees near Slovenian high-mountainous Alpine lakes

    Directory of Open Access Journals (Sweden)

    Darko Ogrin

    1998-01-01

    Full Text Available Analysed by means of standard dendrochronological and dendroclimatological processes were about 100 spruce and larch samples from the lake areas of Jezera on Planina pri Jezeru, Jezera v Ledvicah and Krnsko Jezero, all in the Julian Alps. Local chronologies mainly include the period from 1920 onwards. Correlation between radial increments and climatic data confirmed certain general anticipations about the relation between climate and increments in the upper forest-line zone, and concurrently exposed the specific influence of local, including non-climatic factors on the growth which can not be satisfactory comprised in dendroclimatological analysis.

  10. Effect of constituent elements in wood on X-ray densitometry measurements

    International Nuclear Information System (INIS)

    Kouris, K.; Tout, R.E.; Gilboy, W.B.; Spyrou, N.M.

    1981-01-01

    Small concentrations of elements introduced into a wood matrix have been shown by calculation to measurably influence the photon mass attenuation coefficient although the corresponding changes in the physical density are negligible. This has implications in dendrochronology where the interpretation of densitometric data is based on X-ray radiographs of wood. The magnitude of such effects has been evaluated for selected elements by simulating various botanical matrices. Significant matrix to matrix differences in the mass attenuation coefficient, in the energy range of interest (5 to 25 keV), have been established as being due to variations in the mineral composition. (author)

  11. Rapid changes in the range limits of Scots pine 4000 years ago

    International Nuclear Information System (INIS)

    Gear, A.J.; Huntley, B.

    1991-01-01

    Paleoecological data provide estimates of response rates to past climate changes. Fossil Pinus sylvestris stumps in far northern Scotland demonstrate former presence of pine trees where conventional pollen evidence of pine forests is lacking. Radiocarbon, dendrochronological, and fine temporal-resolution palynological data show that pine forest were present for about four centuries some 4,000 years ago; the forests expanded and then retreated rapidly some 70 to 80 kilometers. Despite the rapidity of this response to climate change, it occurred at rates slower by an order of magnitude than those necessary to maintain equilibrium with forecast climate changes attributed to the greenhouse effect

  12. The genetic algorithm for a signal enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Karimova, L. [Laboratory of Computer Modelling, Institute of Mathematics, Pushkin Street 125, 480100 Almaty (Kazakhstan)]. E-mail: karimova@math.kz; Kuadykov, E. [Laboratory of Computer Modelling, Institute of Mathematics, Pushkin Street 125, 480100 Almaty (Kazakhstan); Makarenko, N. [Laboratory of Computer Modelling, Institute of Mathematics, Pushkin Street 125, 480100 Almaty (Kazakhstan)

    2004-11-21

    The paper is devoted to the problem of time series enhancement, which is based on the analysis of local regularity. The model construction using this analysis does not require any a priori assumption on the structure of the noise and the functional relationship between original signal and noise. The signal itself may be nowhere differentiable with rapidly varying local regularity, what is overcome with the help of the new technique of increasing the local Hoelder regularity of the signal under research. A new signal with prescribed regularity is constructed using the genetic algorithm. This approach is applied to enhancement of time series in the paleoclimatology, solar physics, dendrochronology, meteorology and hydrology.

  13. 13C/12C ratio variations in Pinus longaeva (bristlecone pine) cellulose during the last millennium

    International Nuclear Information System (INIS)

    Grinsted, M.J.; Wilson, A.T.; Ferguson, C.W.

    1979-01-01

    Delta 13 C values are presented for cellulose samples prepared from two dendrochronologically dated Pinus longaeva (bristlecone pine) trees which grew during the last 1000 years. Delta 13 C variations for these forest border trees are similar to upper tree line ring-width variations for the same species and English high summer temperature variations for the same time period. However, the delta 13 C variations appear to be unrelated to lower forest border ring-width variations and cellulose deltaD variations for the same specimens. (Auth.)

  14. Abstracts of the Atlantic Geoscience Society's 2007 colloquium and annual general meeting

    International Nuclear Information System (INIS)

    Johnson, S.; Parkhill, M.; Wilson, R.; Desrosiers, M.; Lentz, D.; Pitre, C.; Pronk, T.; Spooner, I.; Toole, R.; Wallace, P.

    2007-01-01

    The Atlantic Geoscience Society (AGS) hosts annual meetings, workshops and field trips to promote a better understanding of the geology of Atlantic Canada. This colloquium highlighted current research in the Atlantic provinces with special sessions devoted to patterns and geohazards in the North Atlantic; late and post-glacial climate change events in eastern Canada; salt matters; tectonic, thermal and resource aspects of Paleozoic to Mesozoic evaporite basins; mineral resources research by students of the Society of Economic Geologists; dendrochronology; a physical volcanology workshop; and, a North American soil geochemical landscape project orientation session. One of the 74 papers presented at this colloquium has been catalogued separately for inclusion in this database

  15. Reconstruction of tritium release history from contaminated groundwater using tree ring analysis

    International Nuclear Information System (INIS)

    Kalin, R.M.; Murphy, C.E. Jr.; Hall, G.

    1995-01-01

    The history of tritium releases to the groundwater from buried waste was reconstructed through dendrochronology. Wood from dated tree rings was sectioned from a cross-section of a tree that was thought to tap the groundwater. Cellulose was chemically separated from the wood. The cellulose was combusted and the water of combustion collected for liquid scintillation counting. The tritium concentration in the rings rose rapidly after 1972 which was prior to the first measurements made in this area. Trends in the tritium concentration of water outcropping to the surface are similar to the trends in tritium concentration in tree rings. 14 refs., 3 figs

  16. Abstracts of the Atlantic Geoscience Society's 2007 colloquium and annual general meeting

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, S.; Parkhill, M.; Wilson, R.; Desrosiers, M.; Lentz, D.; Pitre, C.; Pronk, T.; Spooner, I.; Toole, R.; Wallace, P. (comps.)

    2007-07-01

    The Atlantic Geoscience Society (AGS) hosts annual meetings, workshops and field trips to promote a better understanding of the geology of Atlantic Canada. This colloquium highlighted current research in the Atlantic provinces with special sessions devoted to patterns and geohazards in the North Atlantic; late and post-glacial climate change events in eastern Canada; salt matters; tectonic, thermal and resource aspects of Paleozoic to Mesozoic evaporite basins; mineral resources research by students of the Society of Economic Geologists; dendrochronology; a physical volcanology workshop; and, a North American soil geochemical landscape project orientation session. One of the 74 papers presented at this colloquium has been catalogued separately for inclusion in this database.

  17. Is Radioactive Decay Really Exponential?

    OpenAIRE

    Aston, Philip J.

    2012-01-01

    Radioactive decay of an unstable isotope is widely believed to be exponential. This view is supported by experiments on rapidly decaying isotopes but is more difficult to verify for slowly decaying isotopes. The decay of 14C can be calibrated over a period of 12,550 years by comparing radiocarbon dates with dates obtained from dendrochronology. It is well known that this approach shows that radiocarbon dates of over 3,000 years are in error, which is generally attributed to past variation in ...

  18. Vzestupy a pády regionálního mocenského centra. Přehled současného stavu poznání pravěkého opevněného areálu na Vladaři v západních Čechách

    Czech Academy of Sciences Publication Activity Database

    Chytráček, Miloslav; Danielisová, Alžběta; Pokorný, P.; Kočár, Petr; Kyselý, René; Kyncl, T.; Sádlo, Jiří; Šmejda, L.; Zavřel, J.

    2012-01-01

    Roč. 103, prosinec (2012), s. 273-338 ISSN 0031-0506 R&D Projects: GA AV ČR IAA8002204 Grant - others:AV ČR(CZ) M300020903 Program:M Institutional research plan: CEZ:AV0Z80020508; CEZ:AV0Z60050516 Institutional support: RVO:67985912 ; RVO:67985939 Keywords : fortified settlement * power center * fortifications * Hallstatt period * La Tène period * cistern * radiocarbon dating * dendrochronological analysis * pollen analysis Subject RIV: AC - Archeology, Anthropology, Ethnology

  19. AMS analyses at ANSTO

    International Nuclear Information System (INIS)

    Lawson, E.M.

    1998-01-01

    The major use of ANTARES is Accelerator Mass Spectrometry (AMS) with 14 C being the most commonly analysed radioisotope - presently about 35 % of the available beam time on ANTARES is used for 14 C measurements. The accelerator measurements are supported by, and dependent on, a strong sample preparation section. The ANTARES AMS facility supports a wide range of investigations into fields such as global climate change, ice cores, oceanography, dendrochronology, anthropology, and classical and Australian archaeology. Described here are some examples of the ways in which AMS has been applied to support research into the archaeology, prehistory and culture of this continent's indigenous Aboriginal peoples. (author)

  20. Establishing a cause and effect relationship for ambient ozone exposure and tree growth in the forest: Progress and an experimental approach

    International Nuclear Information System (INIS)

    Manning, William J.

    2005-01-01

    Much has been written about the effects of ambient ozone on tree growth. Cause and effect has been established with seedlings in chambers. Results from multi-year studies with older tree seedlings, in open-top chambers, have been inconclusive, due to chamber effects. Extrapolation of results from chambers to trees in the forest is not possible. Predictive models for forest tree growth reductions caused by ozone have been developed, but not verified. Dendrochronological methods have been used to establish correlations between radial growth reductions in forest trees and ambient ozone exposure. The protective chemical ethylenediurea (EDU) has been used to protect tree seedlings from ozone injury. An experimental approach is advocated here that utilizes forest trees selected for sensitivity and non-sensitivity to ozone, dendrochronological methods, the protective chemical EDU, and monitoring data for ambient ozone, stomatal conductance, soil moisture potential, air temperature, PAR, etc. in long-term investigations to establish cause and effect relationships. - Progress is reviewed and an experimental approach is proposed to demonstrate a cause and effect relationship for ambient ozone and forest tree growth

  1. Tuning the Voices of a Choir: Detecting Ecological Gradients in Time-Series Populations.

    Directory of Open Access Journals (Sweden)

    Allan Buras

    Full Text Available This paper introduces a new approach-the Principal Component Gradient Analysis (PCGA-to detect ecological gradients in time-series populations, i.e. several time-series originating from different individuals of a population. Detection of ecological gradients is of particular importance when dealing with time-series from heterogeneous populations which express differing trends. PCGA makes use of polar coordinates of loadings from the first two axes obtained by principal component analysis (PCA to define groups of similar trends. Based on the mean inter-series correlation (rbar the gain of increasing a common underlying signal by PCGA groups is quantified using Monte Carlo Simulations. In terms of validation PCGA is compared to three other existing approaches. Focusing on dendrochronological examples, PCGA is shown to correctly determine population gradients and in particular cases to be advantageous over other considered methods. Furthermore, PCGA groups in each example allowed for enhancing the strength of a common underlying signal and comparably well as hierarchical cluster analysis. Our results indicate that PCGA potentially allows for a better understanding of mechanisms causing time-series population gradients as well as objectively enhancing the performance of climate transfer functions in dendroclimatology. While our examples highlight the relevance of PCGA to the field of dendrochronology, we believe that also other disciplines working with data of comparable structure may benefit from PCGA.

  2. Bacterial canker on kiwifruit in Italy: anatomical changes in the wood and in the primary infection sites.

    Science.gov (United States)

    Renzi, Marsilio; Copini, Paul; Taddei, Anna R; Rossetti, Antonio; Gallipoli, Lorenzo; Mazzaglia, Angelo; Balestra, Giorgio M

    2012-09-01

    The bacterial canker of kiwifruit caused by Pseudomonas syringae pv. actinidiae is a severe threat to kiwifruit production worldwide. Many aspects of P. syringae pv. actinidiae biology and epidemiology still require in-depth investigation. The infection by and spread of P. syringae pv. actinidiae in xylem and phloem was investigated by carrying out artificial inoculation experiments with histological and dendrochronological analyses of naturally diseased plants in Italy. We found that the bacterium can infect host plants by entering natural openings and lesions. In naturally infected kiwifruit plants, P. syringae pv. actinidiae is present in the lenticels as well as in the dead phloem tissue beneath the lenticels, surrounded by a lesion in the periderm which appears to indicate the importance of lenticels to kiwifruit infection. Biofilm formation was observed outside and inside plants. In cases of advanced stages of P. syringae pv. actinidiae infection, neuroses of the phloem occur, which are followed by cambial dieback and most likely by infection of the xylem. Anatomical changes in wood such as reduced ring width, a drastic reduction in vessel size, and the presence of tyloses were observed within several infected sites. In the field, these changes occur only a year after the first leaf symptoms are observed suggesting a significant time lapse between primary and secondary symptoms. It was possible to study the temporal development of P. syringae pv. actinidiae-induced cambial dieback by applying dendrochronology methods which revealed that cambial dieback occurs only during the growing season.

  3. Tuning the Voices of a Choir: Detecting Ecological Gradients in Time-Series Populations.

    Science.gov (United States)

    Buras, Allan; van der Maaten-Theunissen, Marieke; van der Maaten, Ernst; Ahlgrimm, Svenja; Hermann, Philipp; Simard, Sonia; Heinrich, Ingo; Helle, Gerd; Unterseher, Martin; Schnittler, Martin; Eusemann, Pascal; Wilmking, Martin

    2016-01-01

    This paper introduces a new approach-the Principal Component Gradient Analysis (PCGA)-to detect ecological gradients in time-series populations, i.e. several time-series originating from different individuals of a population. Detection of ecological gradients is of particular importance when dealing with time-series from heterogeneous populations which express differing trends. PCGA makes use of polar coordinates of loadings from the first two axes obtained by principal component analysis (PCA) to define groups of similar trends. Based on the mean inter-series correlation (rbar) the gain of increasing a common underlying signal by PCGA groups is quantified using Monte Carlo Simulations. In terms of validation PCGA is compared to three other existing approaches. Focusing on dendrochronological examples, PCGA is shown to correctly determine population gradients and in particular cases to be advantageous over other considered methods. Furthermore, PCGA groups in each example allowed for enhancing the strength of a common underlying signal and comparably well as hierarchical cluster analysis. Our results indicate that PCGA potentially allows for a better understanding of mechanisms causing time-series population gradients as well as objectively enhancing the performance of climate transfer functions in dendroclimatology. While our examples highlight the relevance of PCGA to the field of dendrochronology, we believe that also other disciplines working with data of comparable structure may benefit from PCGA.

  4. [Responses of Picea likiangensis radial growth to climate change in the Small Zhongdian area of Yunnan Province, Southwest China].

    Science.gov (United States)

    Zhao, Zhi-Jiang; Tan, Liu-Yi; Kang, Dong-Wei; Liu, Qi-Jing; Li, Jun-Qing

    2012-03-01

    Picea likiangensis (Franch. ) Pritz. primary forest is one of the dominant forest types in the Small Zhongdian area in Shangri-La County of Yunnan Province. In this paper, the responses of P. likiangensis tree-ring width to climate change were analyzed by dendrochronological methods, and the dendrochronology was built by using relatively conservative detrending negative exponential curves or linear regression. Correlation analysis and response function analysis were applied to explore the relationships between the residual chronology series (RES) and climatic factors at different time scales, and pointer year analysis was used to explain the reasons of producing narrow and wide rings. In the study area, the radial growth of P. likiangensis and the increasing air temperature from 1990 to 2008 had definite 'abruption'. The temperature and precipitation in previous year growth season were the main factors limiting the present year radial growth, and especially, the temperature in previous July played a negative feedback role in the radial growth, while the sufficient precipitation in previous July promoted the radial growth. The differences in the temperature variation and precipitation variation in previous year were the main reasons for the formation of narrow and wide rings. P. likiangensis radial growth was not sensitive to the variation of PDSI.

  5. Native American depopulation, reforestation, and fire regimes in the Southwest United States, 1492-1900 CE.

    Science.gov (United States)

    Liebmann, Matthew J; Farella, Joshua; Roos, Christopher I; Stack, Adam; Martini, Sarah; Swetnam, Thomas W

    2016-02-09

    Native American populations declined between 1492 and 1900 CE, instigated by the European colonization of the Americas. However, the magnitude, tempo, and ecological effects of this depopulation remain the source of enduring debates. Recently, scholars have linked indigenous demographic decline, Neotropical reforestation, and shifting fire regimes to global changes in climate, atmosphere, and the Early Anthropocene hypothesis. In light of these studies, we assess these processes in conifer-dominated forests of the Southwest United States. We compare light detection and ranging data, archaeology, dendrochronology, and historical records from the Jemez Province of New Mexico to quantify population losses, establish dates of depopulation events, and determine the extent and timing of forest regrowth and fire regimes between 1492 and 1900. We present a new formula for the estimation of Pueblo population based on architectural remains and apply this formula to 18 archaeological sites in the Jemez Province. A dendrochronological study of remnant wood establishes dates of terminal occupation at these sites. By combining our results with historical records, we report a model of pre- and post-Columbian population dynamics in the Jemez Province. Our results indicate that the indigenous population of the Jemez Province declined by 87% following European colonization but that this reduction occurred nearly a century after initial contact. Depopulation also triggered an increase in the frequency of extensive surface fires between 1640 and 1900. Ultimately, this study illustrates the quality of integrated archaeological and paleoecological data needed to assess the links between Native American population decline and ecological change after European contact.

  6. Impact of soil drainage to the radial stem growth of Norway spruce (Picea Abies L. Karst. in peatland forests

    Directory of Open Access Journals (Sweden)

    Klempířová Barbora

    2013-12-01

    Full Text Available Peatland Norway spruce (Picea abies L. Karst. forests represent very valuable ecosystems with considerable importance for nature conservation. However, a lot of peatland forests have been drained or used for opencast mining of peat. Since dendrochronological and dendroecological studies on trees growing on peatlands in Europe are not many, this study aimed to reconstruct the impact of drainage to the growth of trees in forest stands older than 100 years in the moment of drainage. Dendrochronological analysis was performed on two 0.25-ha square sampling plots (50*50 m in two pre-selected stands (control site vs. drained site with similar natural conditions and age. The mean-value functions of the ring indices, comparing the drained site with the control site, in the period after 1940 revealed very similar radial-growth trends. After the year 1992, when one site was substantially drained, the radial-growth trends not showed any significant change. Likewise, the result of the independent two sample t-test for the period after 1992 has not revealed any substantial statistically important difference in the mean index between the control site and the drained site.

  7. A stable-isotope tree-ring timescale of the Late Glacial/Holocene boundary

    International Nuclear Information System (INIS)

    Becker, Bernd; Kromer, Bernd; Trimborn, Peter

    1991-01-01

    Late Glacial and Holocene tree-ring chronologies, like deep-sea sediments or polar ice cores, contain information about past environments. Changes in tree-ring growth rates can be related to past climate anomalies and changes in the isotope composition of tree-ring cellulose reflect changes in the composition of the atmosphere and the hydrosphere. We have established a 9,928-year absolutely dated dendrochronological record of Holocene oak (Quercus robur, Quercus petraea)-and a 1,604-year floating Late Glacial and Early Holocene chronology of pine (Pinus sylvestris) from subfossil tree remnants deposited in alluvial terraces of south central European rivers. The pine sequence provides records of dendro-dated 14 C, 13 C and 2 H patterns for the late Younger Dryas and the entire Preboreal (10,100-9,000 yr BP). Through the use of dendrochronology, radiocarbon age calibration and stable isotope analysis, we suggest that the Late Glacial/Holocene transition may be identified and dated by 13 C and 2 H tree-ring chronologies. (author)

  8. Lake trout otolith chronologies as multidecadal indicators of high-latitude freshwater ecosystems

    Science.gov (United States)

    Black, B.A.; Von Biela, V.R.; Zimmerman, C.E.; Brown, Randy J.

    2013-01-01

    High-latitude ecosystems are among the most vulnerable to long-term climate change, yet continuous, multidecadal indicators by which to gauge effects on biology are scarce, especially in freshwater environments. To address this issue, dendrochronology (tree-ring analysis) techniques were applied to growth-increment widths in otoliths from lake trout (Salvelinus namaycush) from the Chandler Lake system, Alaska (68.23°N, 152.70°W). All otoliths were collected in 1987 and exhibited highly synchronous patterns in growth-increment width. Increments were dated, the widths were measured, and age-related growth declines were removed using standard dendrochronology techniques. The detrended time series were averaged to generate an annually resolved chronology, which continuously spanned 1964–1984. The chronology positively and linearly correlated with August air temperature over the 22-year interval (p fish metabolic rate or lake productivity. Given the broad distribution of lake trout within North America, this study suggests that otolith chronologies could be used to examine responses between freshwater ecosystems and environmental variability across a range of temporal and spatial scales.

  9. A multi-technique chemical characterization of a Stradivari decorated violin top plate

    Science.gov (United States)

    Malagodi, M.; Canevari, C.; Bonizzoni, L.; Galli, A.; Maspero, F.; Martini, M.

    2013-08-01

    This paper focuses on the characterization of the materials of a violin top plate made by Antonio Stradivari (17th century), with different diagnostic techniques and with an integrated and non-destructive analytical methodology to study surface coatings and decorations. The UV-induced visible fluorescence, optical digital microscopy, ED-XRF associated with micro-FTIR spectroscopy analysis, and dendrochronology were performed. The investigations were aimed to identify the presence of original varnish layers and to characterize the composition of the decorations, either the inlaid purflings or the composite false-inlay strip between them. Several results were achieved: (i) evidence of the absence of varnish layers on the surface as a result of extended and inappropriate restoring; (ii) identification of the dye used for the black layers of the purflings; (iii) characterization of the black matrix and the white elements of the decoration. Furthermore, a dendrochronological dating was performed. A copy of the top plate was realized with materials similar to those identified on the Stradivari original; the same analyses performed on the original model were carried out on the same areas of the copy.

  10. Lake trout otolith chronologies as multidecadal indicators of high-latitude freshwater ecosystems

    Science.gov (United States)

    Black, B.A.; Von Biela, V.R.; Zimmerman, C.E.; Brown, Randy J.

    2013-01-01

    High-latitude ecosystems are among the most vulnerable to long-term climate change, yet continuous, multidecadal indicators by which to gauge effects on biology are scarce, especially in freshwater environments. To address this issue, dendrochronology (tree-ring analysis) techniques were applied to growth-increment widths in otoliths from lake trout (Salvelinus namaycush) from the Chandler Lake system, Alaska (68.23°N, 152.70°W). All otoliths were collected in 1987 and exhibited highly synchronous patterns in growth-increment width. Increments were dated, the widths were measured, and age-related growth declines were removed using standard dendrochronology techniques. The detrended time series were averaged to generate an annually resolved chronology, which continuously spanned 1964–1984. The chronology positively and linearly correlated with August air temperature over the 22-year interval (p otolith chronologies could be used to examine responses between freshwater ecosystems and environmental variability across a range of temporal and spatial scales.

  11. Dendroclimate evidence for extreme hydrologic events over the late Holocene in the Northeastern United States

    Science.gov (United States)

    Pearl, J. K.; Anchukaitis, K. J.; Pederson, N.; Donnelly, J. P.

    2017-12-01

    Extreme hydrologic events pose a present and future threat to cities and infrastructure in the densely populated coastal corridor of the northeastern United States (NE). An understanding of the potential range and return interval of storms, floods, and droughts is important for improving coastal management and hazard planning, as well as the detection and attribution of trends in regional climate phenomena. Here, we examine a suite of evidence for Common Era paleohydroclimate extreme events in the NE. Our study analyzes a network of hydroclimate sensitive trees, subfossil 'drowned' forests and co-located sediment records, using both classical and isotope dendrochronology, radiocarbon analyses, and sediment stratigraphy. Atlantic White cedar (AWC) forests grow along the NE coast and are exposed to severe coastal weather, as they are typically most successful in near-shore, glacially formed depressions. Many coastal AWC sites are ombrotrophic and contain a precipitation or drought signal in their ring widths. Sub-fossil AWC forests are found where near-shore swamps were drowned and exposed to the ocean. Additionally, the rings of coastal AWC may contain the geochemical signature of landfalling tropical cyclones, which bring with them a large influx of precipitation with distinct oxygen isotopes, which can be used to identify these large storms. Dendrochronology, radiocarbon dating, and analysis of sediment cores are used here to identify and date the occurrence of large overwash events along the coastline of the northeastern United States associated with extreme storms.

  12. Potential and limitation of combining terrestrial and marine growth records from Iceland

    Science.gov (United States)

    Piermattei, A.; Urbinati, C.; Tonelli, E.; Eggertsson, Ó.; Levanič, T.; Kaczka, R. J.; Andrew, C.; Schöne, B. R.; Büntgen, U.

    2017-08-01

    Seasonally formed, perennial growth increments of various organisms may possibly contain information about past environmental changes, well before instrumental measurements occurred. Such annually resolved proxy records have been mainly obtained from terrestrial archives, with a paucity of similar data originating from marine habitats. Iceland represents ideal conditions to develop both, tree ring (dendro) and bivalve shell (sclero) chronologies from adjacent sites. Here we introduce the first network of Icelandic birch (Betula pubescens Ehrh.) and rowan (Sorbus aucuparia) dendrochronologies, as well as ocean quahog (Arctica islandica L.) sclerochronologies. In order to identify the dominant external drivers of tree and shell growth, we assess the common growth trends and growth extremes within and between the terrestrial and marine records, as well as relationships of both archives with instrumental-based meteorological indices. Capturing a strong signal of June-August mean air temperature, the dendrochronologies are significantly positively correlated to each other. The sclerochronologies, however, reveal much lower growth coherency, which likely results from different sampling strategies and growth habitats. Disagreement between the dendro- and sclerochronologies possibly originates from unequal sample size, offset in the seasonal timing and rate of the growth, as well as varying sensitivities to different environmental factors. Our results emphasize the importance of considering a wide range of species and taxa to reconstruct a more complete picture of terrestrial and marine ecosystem functioning and productivity across various spatiotemporal scales.

  13. Dendrogeochronologic and Anatomic Analysis of Excavated Plains Cottonwoods Determine Overbank Sedimentation Rates and Historical Channel Positions Along the Interior of a Migrating Meander Bend, Powder River, Montana

    Science.gov (United States)

    Metzger, T. L.; Pizzuto, J. E.; Schook, D. M.; Hasse, T. R.; Affinito, R. A.

    2017-12-01

    Dendrochronological dating of buried trees precisely determines the germination year and identifies the stratigraphic context of germination for the trees. This recently developed application of dendrochronology provides accurate time-averaged sedimentation rates of overbank deposition along floodplains and can be used to identify burial events. Previous studies have demonstrated that tamarisk (Tamarix ramosissima) and sandbar willow (Salix exigua) develop anatomical changes within the tree rings (increased vessel size and decreased ring widths) on burial, but observations of plains cottonwood (Populus deltoides ssp. monilifera) are lacking. In September 2016 and June 2017, five buried plains cottonwoods were excavated along a single transect of the interior of a meander bend of the Powder River, Montana. Sediment samples were obtained near each tree for 210Pb and 137Cs dating, which will allow for comparison between dendrochronological and isotopic dating methods. The plains cottonwood samples collected exhibit anatomical changes associated with burial events that are observed in other species. All trees germinated at the boundary between thinly bedded fine sand and mud and coarse sand underlain by sand and gravel, indicating plains cottonwoods germinate on top of point bars prior to overbank deposition. The precise germination age and depth provide elevations and minimum age constraints for the point bar deposits and maximum ages for the overlying sediment, helping constrain past channel positions and overbank deposition rates. Germination years of the excavated trees, estimated from cores taken 1.5 m above ground level, range from 2014 to 1862. Accurate establishment years determined by cross-dating the buried section of the tree can add an additional 10 years to the cored age. The sedimentation rate and accumulation thickness varied with tree age. The germination year, total sediment accumulation, and average sedimentation rate at the five sampled trees is

  14. Missing Rings in Pinus halepensis – The Missing Link to Relate the Tree-Ring Record to Extreme Climatic Events

    Science.gov (United States)

    Novak, Klemen; de Luis, Martin; Saz, Miguel A.; Longares, Luis A.; Serrano-Notivoli, Roberto; Raventós, Josep; Čufar, Katarina; Gričar, Jožica; Di Filippo, Alfredo; Piovesan, Gianluca; Rathgeber, Cyrille B. K.; Papadopoulos, Andreas; Smith, Kevin T.

    2016-01-01

    Climate predictions for the Mediterranean Basin include increased temperatures, decreased precipitation, and increased frequency of extreme climatic events (ECE). These conditions are associated with decreased tree growth and increased vulnerability to pests and diseases. The anatomy of tree rings responds to these environmental conditions. Quantitatively, the width of a tree ring is largely determined by the rate and duration of cell division by the vascular cambium. In the Mediterranean climate, this division may occur throughout almost the entire year. Alternatively, cell division may cease during relatively cool and dry winters, only to resume in the same calendar year with milder temperatures and increased availability of water. Under particularly adverse conditions, no xylem may be produced in parts of the stem, resulting in a missing ring (MR). A dendrochronological network of Pinus halepensis was used to determine the relationship of MR to ECE. The network consisted of 113 sites, 1,509 trees, 2,593 cores, and 225,428 tree rings throughout the distribution range of the species. A total of 4,150 MR were identified. Binomial logistic regression analysis determined that MR frequency increased with increased cambial age. Spatial analysis indicated that the geographic areas of south-eastern Spain and northern Algeria contained the greatest frequency of MR. Dendroclimatic regression analysis indicated a non-linear relationship of MR to total monthly precipitation and mean temperature. MR are strongly associated with the combination of monthly mean temperature from previous October till current February and total precipitation from previous September till current May. They are likely to occur with total precipitation lower than 50 mm and temperatures higher than 5°C. This conclusion is global and can be applied to every site across the distribution area. Rather than simply being a complication for dendrochronology, MR formation is a fundamental response of trees

  15. Missing Rings in Pinus halepensis - The Missing Link to Relate the Tree-Ring Record to Extreme Climatic Events.

    Science.gov (United States)

    Novak, Klemen; de Luis, Martin; Saz, Miguel A; Longares, Luis A; Serrano-Notivoli, Roberto; Raventós, Josep; Čufar, Katarina; Gričar, Jožica; Di Filippo, Alfredo; Piovesan, Gianluca; Rathgeber, Cyrille B K; Papadopoulos, Andreas; Smith, Kevin T

    2016-01-01

    Climate predictions for the Mediterranean Basin include increased temperatures, decreased precipitation, and increased frequency of extreme climatic events (ECE). These conditions are associated with decreased tree growth and increased vulnerability to pests and diseases. The anatomy of tree rings responds to these environmental conditions. Quantitatively, the width of a tree ring is largely determined by the rate and duration of cell division by the vascular cambium. In the Mediterranean climate, this division may occur throughout almost the entire year. Alternatively, cell division may cease during relatively cool and dry winters, only to resume in the same calendar year with milder temperatures and increased availability of water. Under particularly adverse conditions, no xylem may be produced in parts of the stem, resulting in a missing ring (MR). A dendrochronological network of Pinus halepensis was used to determine the relationship of MR to ECE. The network consisted of 113 sites, 1,509 trees, 2,593 cores, and 225,428 tree rings throughout the distribution range of the species. A total of 4,150 MR were identified. Binomial logistic regression analysis determined that MR frequency increased with increased cambial age. Spatial analysis indicated that the geographic areas of south-eastern Spain and northern Algeria contained the greatest frequency of MR. Dendroclimatic regression analysis indicated a non-linear relationship of MR to total monthly precipitation and mean temperature. MR are strongly associated with the combination of monthly mean temperature from previous October till current February and total precipitation from previous September till current May. They are likely to occur with total precipitation lower than 50 mm and temperatures higher than 5°C. This conclusion is global and can be applied to every site across the distribution area. Rather than simply being a complication for dendrochronology, MR formation is a fundamental response of trees

  16. Quantifying climate-growth relationships at the stand level in a mature mixed-species conifer forest.

    Science.gov (United States)

    Teets, Aaron; Fraver, Shawn; Weiskittel, Aaron R; Hollinger, David Y

    2018-03-11

    A range of environmental factors regulate tree growth; however, climate is generally thought to most strongly influence year-to-year variability in growth. Numerous dendrochronological (tree-ring) studies have identified climate factors that influence year-to-year variability in growth for given tree species and location. However, traditional dendrochronology methods have limitations that prevent them from adequately assessing stand-level (as opposed to species-level) growth. We argue that stand-level growth analyses provide a more meaningful assessment of forest response to climate fluctuations, as well as the management options that may be employed to sustain forest productivity. Working in a mature, mixed-species stand at the Howland Research Forest of central Maine, USA, we used two alternatives to traditional dendrochronological analyses by (1) selecting trees for coring using a stratified (by size and species), random sampling method that ensures a representative sample of the stand, and (2) converting ring widths to biomass increments, which once summed, produced a representation of stand-level growth, while maintaining species identities or canopy position if needed. We then tested the relative influence of seasonal climate variables on year-to-year variability in the biomass increment using generalized least squares regression, while accounting for temporal autocorrelation. Our results indicate that stand-level growth responded most strongly to previous summer and current spring climate variables, resulting from a combination of individualistic climate responses occurring at the species- and canopy-position level. Our climate models were better fit to stand-level biomass increment than to species-level or canopy-position summaries. The relative growth responses (i.e., percent change) predicted from the most influential climate variables indicate stand-level growth varies less from to year-to-year than species-level or canopy-position growth responses. By

  17. Nonannual tree rings in a climate-sensitive Prioria copaifera chronology in the Atrato River, Colombia.

    Science.gov (United States)

    Herrera-Ramirez, David; Andreu-Hayles, Laia; Del Valle, Jorge I; Santos, Guaciara M; Gonzalez, Paula L M

    2017-08-01

    In temperate climates, tree growth dormancy usually ensures the annual nature of tree rings, but in tropical environments, determination of annual periodicity can be more complex. The purposes of the work are as follows: (1) to generate a reliable tree-ring width chronology for Prioria copaifera Griseb. (Leguminoceae), a tropical tree species dwelling in the Atrato River floodplains, Colombia; (2) to assess the climate signal recorded by the tree-ring records; and (3) to validate the annual periodicity of the tree rings using independent methods. We used standard dendrochronological procedures to generate the P. copaifera tree-ring chronology. We used Pearson correlations to evaluate the relationship of the chronology with the meteorological records, climate regional indices, and gridded precipitation/sea surface temperature products. We also evaluated 24 high-precision 14 C measurements spread over a range of preselected tree rings, with assigned calendar years by dendrochronological techniques, before and after the bomb spike in order to validate the annual nature of the tree rings. The tree-ring width chronology was statistically reliable, and it correlated significantly with local records of annual and October-December (OND) streamflow and precipitation across the upper river watershed (positive), and OND temperature (negative). It was also significantly related to the Oceanic Niño Index, Pacific Decadal Oscillation, and the Southern Oscillation Index, as well as sea surface temperatures over the Caribbean and the Pacific region. However, 14 C high-precision measurements over the tree rings demonstrated offsets of up to 40 years that indicate that P. copaifera can produce more than one ring in certain years. Results derived from the strongest climate-growth relationship during the most recent years of the record suggest that the climatic signal reported may be due to the presence of annual rings in some of those trees in recent years. Our study alerts about

  18. Using intra annual density fluctuations and d13C to assess the impact of summer drought on Mediterranean ecosystem

    Science.gov (United States)

    Battipaglia, G.; Brand, W. A.; Linke, P.; Schaefer, I.; Noetzli, M.; Cherubini, P.

    2009-04-01

    Tree- ring growth and wood density have been used extensively as indicators of climate change, and tree-ring has been commonly applied as a proxy estimate for seasonal integration of temperatures and precipitation with annual resolution (Hughes 2002). While these relationships have been well established in temperate ecosystems (Fritts, 1976; Schweingruber, 1988, Briffa et al., 1998, 2004), in Mediterranean region dendrochronological studies are still scarce (Cherubini et al, 2003). In Mediterranean environment, trees may form intra-annual density fluctuations, also called "false rings" or "double rings" (Tingley 1937; Schulman 1938). They are usually induced by sudden drought events, occurring during the vegetative period, and, allowing intra-annual resolution, they may provide detailed information at a seasonal level, as well as species-specific sensitivity to drought. We investigated the variability of tree- ring width and carbon stable isotopes of a Mediterranean species, Arbutus unedo L., sampled on Elba island, (Tuscany, Italy). The samples were taken at two different sites, one characterized by wet and one by dry conditions. d13C was measured using Laser- Ablation- Combustion -GC-IRMS. Here, we present first results showing the impact of drought on tree growth and on false ring formation at the different sites and we underline the importance of using Laser Ablation to infer drought impact at the intra -annual level. Briffa KR, Schweingruber FH, Jones PD, Osborn TJ, Harris IC, Shiyatov SG, Vaganov EA, Grudd H (1998) Trees tell of past climates: but are they speaking less clearly today? Phil Transact Royal Soc London 353:65-73 Briffa KR, Osborn TJ, Schweingruber FH (2004) Large-scale temperature inferences from tree rings: a review. Glob Panet Change 40:11-26 Cherubini, P., B.L. Gartner, R. Tognetti, O.U. Bräker, W. Schoch & J.L. Innes. 2003. Identification, measurement and interpretation of tree rings in woody species from Mediterranean climates. Biol. Rev

  19. [Responses of Pinus sylvestris var. mongolica radial growth to climate warming in Great Xing' an Mountins: a case study in Mangui].

    Science.gov (United States)

    Zhang, Xing-Liang; He, Xing-Yuan; Chen, Zhen-Ju; Cui, Ming-Xing; Li, Na

    2011-12-01

    Based on the theory and methodology of dendrochronology, the tree ring width chronology of Pinus sylvestris var. mongolica in Mangui of Great Xing' an Mountains was developed, and the relationships between the standardized tree ring width chronology and local climate factors (temperature and precipitation) as well as the effects of climate factors on the P. sylvestris var. mongolica radial growth were analyzed. In this region, the mean monthly temperature in April-August of current year was the main factor limiting the radial growth, and the increasing mean monthly temperature from April to August had negative effects to the radial growth. The simulation of the variations of the radial growth by the mean monthly temperature change in April-August showed that the radial growth of P. sylvestris var. mongolica would present a declining trend accompanied with the warmer and drier regional climate condition.

  20. 884 Cal.BP and all that

    International Nuclear Information System (INIS)

    Switsur, Roy

    1986-01-01

    A history of the development of the technique of radiocarbon dating highlights the two problems with this method. The first is calibration; the radiocarbon calendar is not linear. However two independent experiments to provide high precision measurements in tree rings have resulted in a high precision calibration curve. The second is how to denote radiocarbon ages and calibrated dates, as this depends on how the dendrochronology time scale used in the calibration is transferred to the actual calendar. If the zero of the dendroscale is transferred from the origin of the Christian calendar to AD 1950, radiocarbon ages are designated CAL BP (BP = before present). There is an alternative method which results in CAL AD and CAL BC. A suggestion for a standard notation is made to avoid the confusion of two systems. (U.K.)

  1. Invasion of Winter Moth in New England: Effects of Defoliation and Site Quality on Tree Mortality

    Directory of Open Access Journals (Sweden)

    Michael J. Simmons

    2014-10-01

    Full Text Available Widespread and prolonged defoliation by the European winter moth, Operophtera brumata L., has occurred in forests of eastern Massachusetts for more than a decade and populations of winter moth continue to invade new areas of New England. This study characterized the forests of eastern Massachusetts invaded by winter moth and related the duration of winter moth defoliation estimated using dendrochronology to observed levels of tree mortality and understory woody plant density. Quercus basal area mortality in mixed Quercus and mixed Quercus—Pinus strobus forests in eastern Massachusetts ranged from 0–30%; mortality of Quercus in these forests was related to site quality and the number of winter moth defoliation events. In addition, winter moth defoliation events lead to a subsequent increase in understory woody plant density. Our results indicate that winter moth defoliation has been an important disturbance in New England forests that may have lasting impacts.

  2. Computer processing of 14C data; statistical tests and corrections of data

    International Nuclear Information System (INIS)

    Obelic, B.; Planinic, J.

    1977-01-01

    The described computer program calculates the age of samples and performs statistical tests and corrections of data. Data are obtained from the proportional counter that measures anticoincident pulses per 20 minute intervals. After every 9th interval the counter measures total number of counts per interval. Input data are punched on cards. The output list contains input data schedule and the following results: mean CPM value, correction of CPM for normal pressure and temperature (NTP), sample age calculation based on 14 C half life of 5570 and 5730 years, age correction for NTP, dendrochronological corrections and the relative radiocarbon concentration. All results are given with one standard deviation. Input data test (Chauvenet's criterion), gas purity test, standard deviation test and test of the data processor are also included in the program. (author)

  3. How to quantify conduits in wood?

    Science.gov (United States)

    Scholz, Alexander; Klepsch, Matthias; Karimi, Zohreh; Jansen, Steven

    2013-01-01

    Vessels and tracheids represent the most important xylem cells with respect to long distance water transport in plants. Wood anatomical studies frequently provide several quantitative details of these cells, such as vessel diameter, vessel density, vessel element length, and tracheid length, while important information on the three dimensional structure of the hydraulic network is not considered. This paper aims to provide an overview of various techniques, although there is no standard protocol to quantify conduits due to high anatomical variation and a wide range of techniques available. Despite recent progress in image analysis programs and automated methods for measuring cell dimensions, density, and spatial distribution, various characters remain time-consuming and tedious. Quantification of vessels and tracheids is not only important to better understand functional adaptations of tracheary elements to environment parameters, but will also be essential for linking wood anatomy with other fields such as wood development, xylem physiology, palaeobotany, and dendrochronology.

  4. The application of carbon-isotope measurements to dendro- and xylem-chronology

    International Nuclear Information System (INIS)

    Yonenobu, Hitoshi; Hattori, Yoshiaki; Kikata, Yoji; Mitsutani, Takumi; Nakamura, Toshio.

    1990-01-01

    We measured 14 C/ 13 C Ratio of the Teak. The 14 C excess, which reflects the execution of the tropospheric nuclear tests, is stamped in the Teak trunk. In place of the annual rings this stamp can estimate the xylem-chronologies and more accurate growth rates of tropical trees which have no annual rings. And replacing the shot-pinning method we can estimate the growing period in an annual ring formed especially in 1963-1966, when the 14 C concentration in the tropospheric air changes dramatically. And we measured 14 C-chronologies of the annual rings of O-Hinoki, 14 C-chronologies agree well with dendrochronologies for the past 600 years. And the 14 C chronologies support more determinative cross-dating of the archaeological samples. (author)

  5. [Effects of elevated ozone on Pinus armandii growth: a simulation study with open-top chamber].

    Science.gov (United States)

    Liu, Chang-Fu; Liu, Chen; He, Xing-Yuan; Ruan, Ya-Nan; Xu, Sheng; Chen, Zhen-Ju; Peng, Jun-Jie; Li, Teng

    2013-10-01

    By using open-top chamber (OTC) and the techniques of dendrochronology, this paper studied the growth of Pinus armandii under elevated ozone, and explored the evolution dynamics and adaptation mechanisms of typical forest ecosystems to ozone enrichment. Elevated ozone inhibited the stem growth of P. armandii significantly, with the annual growth of the stem length and diameter reduced by 35.0% and 12.9%, respectively. The annual growth of tree-ring width and the annual ring cells number decreased by 11.5% and 54.1%, respectively, but no significant change was observed in the diameter of tracheid. At regional scale, the fluctuation of ozone concentration showed significant correlation with the variation of local vegetation growth (NDVI).

  6. Reconstructing disturbances and their biogeochemical consequences over multiple timescales

    Science.gov (United States)

    McLauchlan, Kendra K.; Higuera, Philip E.; Gavin, Daniel G.; Perakis, Steven S.; Mack, Michelle C.; Alexander, Heather; Battles, John; Biondi, Franco; Buma, Brian; Colombaroli, Daniele; Enders, Sara K.; Engstrom, Daniel R.; Hu, Feng Sheng; Marlon, Jennifer R.; Marshall, John; McGlone, Matt; Morris, Jesse L.; Nave, Lucas E.; Shuman, Bryan; Smithwick, Erica A.H.; Urrego, Dunia H.; Wardle, David A.; Williams, Christopher J.; Williams, Joseph J.

    2014-01-01

    Ongoing changes in disturbance regimes are predicted to cause acute changes in ecosystem structure and function in the coming decades, but many aspects of these predictions are uncertain. A key challenge is to improve the predictability of postdisturbance biogeochemical trajectories at the ecosystem level. Ecosystem ecologists and paleoecologists have generated complementary data sets about disturbance (type, severity, frequency) and ecosystem response (net primary productivity, nutrient cycling) spanning decadal to millennial timescales. Here, we take the first steps toward a full integration of these data sets by reviewing how disturbances are reconstructed using dendrochronological and sedimentary archives and by summarizing the conceptual frameworks for carbon, nitrogen, and hydrologic responses to disturbances. Key research priorities include further development of paleoecological techniques that reconstruct both disturbances and terrestrial ecosystem dynamics. In addition, mechanistic detail from disturbance experiments, long-term observations, and chronosequences can help increase the understanding of ecosystem resilience.

  7. Secular variation of cosmic ray intensity recorded in the radiocarbon concentration of tree rings

    International Nuclear Information System (INIS)

    Kigoshi, K.

    1978-01-01

    Study of the secular variations of cosmic ray intensity on the basis of the secular variations of atmospheric radiocarbon concentration in 8000 years is considered. The data on the radiocarbon concentration is received by three laboratories using the dendrochronologically dated tree ring samples. In order to use the data the variations due to geochemical process must be eliminated. From this point of view the climatic effect on the atmospheric radiocarbon concenttration is estimated using the data on sunspot number and global surface temperature during 1650-1800 y. The barge influence of climate on the atmospheric radiocarbon concentration syggests the small contribution of change of radiocarbon production rate to the short-period fluctuations in the atmospheric radiocarbon concentration. Elimination of variations caused by climate and sunspot activities from the variations in atmospheric radiocarbon concentration gives a long-term scale of its concentration which agrees well to the observed paleo-geomagnetic data

  8. Effects of Initial Stand Density and Climate on Red Pine Productivity within Huron National Forest, Michigan, USA

    Directory of Open Access Journals (Sweden)

    Joseph O'Brien

    2012-12-01

    Full Text Available Changes in climate are predicted to significantly affect the productivity of trees in the Great Lakes region over the next century. Forest management decisions, such as initial stand density, can promote climatic resiliency and moderate decreased productivity through the reduction of tree competition. The influences of climate (temperature and precipitation and forest management (initial stand density on the productivity of red pine (Pinus resinosa across multiple sites within Huron National Forest, Michigan, were examined using dendrochronological methods. Two common planting regimes were compared in this analysis; low initial density (1977 trees per hectare. Low initial density stands were found to have a higher climatic resilience by combining equal or greater measures of productivity, while having a reduced sensitivity to monthly and seasonal climate, particularly to summer drought.

  9. High resolution 14C dating of surface peat using the AMS technique

    International Nuclear Information System (INIS)

    Tolonen, K.; Possnert, G.; Jungner, H.; Sonninen, E.; Alm, J.

    1992-01-01

    In an AMS (Accelerator Mass Spectrometric) determination of 14 C from moss-increment dated samples from a Sphagnum fuscum hummock, a clear peak representing the time of high 14 C activity in the atmosphere due to nuclear bomb tests was found. The C-14 activities in the peat profile at deeper levels, corresponding to the period down to 1600 Bp, showed similar variations as the atmospheric values. The time scale obtained from radiocarbon dating fitted well with results from moss-increment counting, pollen analysis and dendrochronological dating of a fire horizon. Using the bomb layers and refixing into growing peat was estimated. The fraction of soil carbon dioxide taken up by the contemporary Sphagnum Sward was thus found to be in the order of 20 %. (orig.). (15 refs., 5 figs., 2 tabs.)

  10. Summer drought reconstruction in northeastern Spain inferred from a tree ring latewood network since 1734

    Science.gov (United States)

    Tejedor, E.; Saz, M. A.; Esper, J.; Cuadrat, J. M.; de Luis, M.

    2017-08-01

    Drought recurrence in the Mediterranean is regarded as a fundamental factor for socioeconomic development and the resilience of natural systems in context of global change. However, knowledge of past droughts has been hampered by the absence of high-resolution proxies. We present a drought reconstruction for the northeast of the Iberian Peninsula based on a new dendrochronology network considering the Standardized Evapotranspiration Precipitation Index (SPEI). A total of 774 latewood width series from 387 trees of P. sylvestris and P. uncinata was combined in an interregional chronology. The new chronology, calibrated against gridded climate data, reveals a robust relationship with the SPEI representing drought conditions of July and August. We developed a summer drought reconstruction for the period 1734-2013 representative for the northeastern and central Iberian Peninsula. We identified 16 extremely dry and 17 extremely wet summers and four decadal scale dry and wet periods, including 2003-2013 as the driest episode of the reconstruction.

  11. Little Ice Age wetting of interior Asian deserts and the rise of the Mongol Empire

    Science.gov (United States)

    Putnam, Aaron E.; Putnam, David E.; Andreu-Hayles, Laia; Cook, Edward R.; Palmer, Jonathan G.; Clark, Elizabeth H.; Wang, Chunzeng; Chen, Feng; Denton, George H.; Boyle, Douglas P.; Bassett, Scott D.; Birkel, Sean D.; Martin-Fernandez, Javier; Hajdas, Irka; Southon, John; Garner, Christopher B.; Cheng, Hai; Broecker, Wallace S.

    2016-01-01

    The degree to which warming of the planet will alter Asia's water resources is an important question for food, energy, and economic security. Here we present geological evidence, underpinned by radiometric dating and dendrochronology, and bolstered by hydrological modeling, indicating that wetter-than-present conditions characterized the core of the inner Asian desert belt during the Little Ice Age, the last major Northern Hemispheric cold spell of the Holocene. These wetter conditions accompanied northern mid-latitude cooling, glacier expansion, a strengthened/southward-shifted boreal jet, and weakened south Asian monsoons. We suggest that southward migration of grasslands in response to these wetter conditions aided the spread of Mongol Empire steppe pastoralists across Asian drylands. Conversely, net drying over the 20th century has led to drought that is unprecedented for the past ∼830 years, and that could intensify with further heating of the Asian continent.

  12. Methods for measuring arctic and alpine shrub growth

    DEFF Research Database (Denmark)

    Myers-Smith, Isla; Hallinger, Martin; Blok, Daan

    2015-01-01

    Shrubs have increased in abundance and dominance in arctic and alpine regions in recent decades. This often dramatic change, likely due to climate warming, has the potential to alter both the structure and function of tundra ecosystems. The analysis of shrub growth is improving our understanding...... of tundra vegetation dynamics and environmental changes. However, dendrochronological methods developed for trees, need to be adapted for the morphology and growth eccentricity of shrubs. Here, we review current and developing methods to measure radial and axial growth, estimate age, and assess growth...... dynamics in relation to environmental variables. Recent advances in sampling methods, analysis and applications have improved our ability to investigate growth and recruitment dynamics of shrubs. However, to extrapolate findings to the biome scale, future dendroecologicalwork will require improved...

  13. The role of summer precipitation and summer temperature in establishment and growth of dwarf shrub Betula nana in northeast Siberian tundra

    DEFF Research Database (Denmark)

    Li, Bingxi; Heijmans, Monique M P D; Berendse, Frank

    2016-01-01

    It is widely believed that deciduous tundra-shrub dominance is increasing in the pan-Arctic region, mainly due to rising temperature. We sampled dwarf birch (Betula nana L.) at a northeastern Siberian tundra site and used dendrochronological methods to explore the relationship between climatic...... variables and local shrub dominance. We found that establishment of shrub ramets was positively related to summer precipitation, which implies that the current high dominance of B. nana at our study site could be related to high summer precipitation in the period from 1960 to 1990. The results confirmed...... that early summer temperature is most influential to annual growth rates of B. nana. In addition, summer precipitation stimulated shrub growth in years with warm summers, suggesting that B. nana growth may be co-limited by summer moisture supply. The dual controlling role of temperature and summer...

  14. The use of wood anatomy features for landslide-risk assessment and early warning - an example from Western Carpathians, Poland

    Science.gov (United States)

    Wistuba, Małgorzata; Malik, Ireneusz; Piątek, Michał; Kojs, Paweł; Kalinowski, Michał; Polowy, Marta

    2013-04-01

    Trees, which grow on active landslide slopes have stems deformed due to the impact of instable ground. Their stems become tilted and bent which results in developing mechanical stresses which influence the structure of wood formed. Deformations occur during the whole life span of a tree and are recorded year-by-year in tree rings. Therefore it is possible to analyse the activity of landslide slopes in the past - through the analysis of tree-ring sequences obtained from living trees. It is also possible to date even small ground movements, otherwise imperceptible without using specialist detectors. Within the studies conducted we have analysed features of wood anatomy of Norway spruce, diagnostic for active landslide slopes: eccentricity and compression wood. The aim of presented study was to check, if it is possible (1) to detect the presence of week, initial ground movements with the use of established dendrochronological approach, (2) to forecast the possible catastrophic landslide event following preparatory phase.In order to fulfill the aim we have analysed the anatomy of spruces growing on landslide slope in Milówska village (foots of Mt Prusów 1020 m a.s.l., southern Poland, flysch Western Carpathians). The slope, basing on geomorphic mapping and observations conducted before 2010, was considered as inactive. However in consequence of heavy rainfalls in May-June 2010 the landslide was abruptly activated. Fast ground movements were catastrophic for inhabitants and buildings in the area. In 2012, in the area affected by landsliding 2 years earlier, we have taken samples (cores) from 25 spruce trees. We have analysed samples in search for growth disturbances: eccentricity and compression wood. We have found that in sampled trees not only the heavy landsliding in 2010 was recorded, but also: (1) symptoms of earlier instability for the last 10-20 years (probable initial landsliding), (2) symptoms of older events from over 50 years ago were detected. Results show

  15. Carbon-14 activity of fallout in Araucaria angustifolia annual growth rings, from Arapoti, Parana State, Brazil

    International Nuclear Information System (INIS)

    Lisi, Claudio Sergio; Pessenda, Luiz Carlos Ruiz; Tomazello Filho, Mario

    2000-01-01

    During the period of nuclear tests between 1950 and 1960, an input of artificial 14 C (fallout effect) occurred in the natural reservoirs. 14 C determinations in the Northern Hemisphere showed values of Δ 14 C up to 960 in the year of 1964. To determine the fallout 14 C activity in Brazil, wood samples from Araucaria angustifolia (Bert.) O. Kuntze, Araucariaceae, were collected in Arapoti-PR (24 deg 11 S , 49 deg 58 O ). The annual tree rings were selected by dendrochronology. The cellulose was extracted and its 14 C activity determined by liquid scintillation method. The results showed a significant increase of the Δ 14 C up to 590 in 1965, about 60% higher than the natural activity, gradually decreasing after the end of nuclear tests. These results were correlated with those obtained in the Northen Hemisphere and will be used in the studies of CO 2 mechanisms distribuition to the atmosphere and other natural reservoirs. (author)

  16. Changes in precipitation, runoff and sediment transport in the Eastern Romania during the period 1950 to 2010

    Science.gov (United States)

    Maria, Radoane; Constantin, Nechita; Francisca, Chiriloaei; Nicolae, Radoane

    2016-04-01

    In this paper are analyzed the climatic and hydrological records from 29 meteorological stations and 48 hydrometric stations which are all overlapping on two big drainage basins (Siret and Prut) from the eastern part of Romania. To these registrations, were added information obtained on basis of more than 20 dendrochronological series collected from the entire surface of the two studied basins. In order to obtain the correlation between radial tree rings growth and climate, were used the climatic data from National Climatic Grid with spatial resolution of 10x10 km. The climatic information obtained on the analysis of dendrochronological series complete the data from the meteorological stations, especially if we consider the fact that some of the tree ages cover older periods than year 1900. Annual series of variables: temperature (T), precipitation (P), number of days from year with sunshine radiation (S) water discharge (Qw), suspended sediments (Qs) cover the time interval 1950-2010. These constitute in a well-known cascade type process of influence transmission: precipitations determine runoff which, in turn, determines erosion. The last variable from this chain - in channel transported sediments and their movement from source to delivery represents a key issue of dynamic geomorphology. The rhythm in which this process occurs may change dramatically, representing the signal of great changes in landform domain (climate changes or human interventions). Climatic, hydrological, dendrochronological time series analysis has the goal the answer the following questions: Which is the spatial variability of these series behavior? Can we identify areas with similar features of series? What factors "complicated" the cascade transmission of P → Qw → Qs variability? Can we identify common thresholds in series change and which are the causes? In Natural vs. Human competition, can we quantify their weight for considered series in the shown geographic space? Using

  17. Sample requirements and design of an inter-laboratory trial for radiocarbon laboratories

    International Nuclear Information System (INIS)

    Bryant, Charlotte; Carmi, Israel; Cook, Gordon; Gulliksen, Steinar; Harkness, Doug; Heinemeier, Jan; McGee, Edward; Naysmith, Philip; Possnert, Goran; Scott, Marian; Plicht, Hans van der; Strydonck, Mark van

    2000-01-01

    An on-going inter-comparison programme which is focused on assessing and establishing consensus protocols to be applied in the identification, selection and sub-sampling of materials for subsequent 14 C analysis is described. The outcome of the programme will provide a detailed quantification of the uncertainties associated with 14 C measurements including the issues of accuracy and precision. Such projects have become recognised as a fundamental aspect of continuing laboratory quality assurance schemes, providing a mechanism for the harmonisation of measurements and for demonstrating the traceability of results. The design of this study and its rationale are described. In summary, a suite of core samples has been defined which will be made available to both AMS and radiometric laboratories. These core materials are representative of routinely dated material and their ages span the full range of the applied 14 C time-scale. Two of the samples are of wood from the German and Irish dendrochronologies, thus providing a direct connection to the master dendrochronological calibration curve. Further samples link this new inter-comparison to past studies. Sample size and precision have been identified as being of paramount importance in defining dating confidence, and so several core samples have been identified for more in-depth study of these practical issues. In addition to the core samples, optional samples have been identified and prepared specifically for either AMS and/or radiometric laboratories. For AMS laboratories, these include bone, textile, leather and parchment samples. Participation in the study requires a commitment to a minimum of 10 core analyses, with results to be returned within a year

  18. Native American depopulation, reforestation, and fire regimes in the Southwest United States, 1492–1900 CE

    Science.gov (United States)

    Liebmann, Matthew J.; Farella, Joshua; Roos, Christopher I.; Stack, Adam; Martini, Sarah

    2016-01-01

    Native American populations declined between 1492 and 1900 CE, instigated by the European colonization of the Americas. However, the magnitude, tempo, and ecological effects of this depopulation remain the source of enduring debates. Recently, scholars have linked indigenous demographic decline, Neotropical reforestation, and shifting fire regimes to global changes in climate, atmosphere, and the Early Anthropocene hypothesis. In light of these studies, we assess these processes in conifer-dominated forests of the Southwest United States. We compare light detection and ranging data, archaeology, dendrochronology, and historical records from the Jemez Province of New Mexico to quantify population losses, establish dates of depopulation events, and determine the extent and timing of forest regrowth and fire regimes between 1492 and 1900. We present a new formula for the estimation of Pueblo population based on architectural remains and apply this formula to 18 archaeological sites in the Jemez Province. A dendrochronological study of remnant wood establishes dates of terminal occupation at these sites. By combining our results with historical records, we report a model of pre- and post-Columbian population dynamics in the Jemez Province. Our results indicate that the indigenous population of the Jemez Province declined by 87% following European colonization but that this reduction occurred nearly a century after initial contact. Depopulation also triggered an increase in the frequency of extensive surface fires between 1640 and 1900. Ultimately, this study illustrates the quality of integrated archaeological and paleoecological data needed to assess the links between Native American population decline and ecological change after European contact. PMID:26811459

  19. The effects of the lodgepole sour gas well blowout on coniferous tree growth

    International Nuclear Information System (INIS)

    Baker, K.A.

    1991-01-01

    A dendrochronological study was used to evaluate growth impacts on White Spruce (Picea glauca (Moench) resulting from the 1982 Lodgepole sour gas well blowout. Stem analysis was evaluated from four ecologically similar monitoring sites located on a 10 kilometre downwind gradient and compared to a control site. Incremental volume was calculated, standardized using running mean filters and analyzed using one-way ANOVA. Pre and post-blowout growth trends were analyzed between sites and were also evaluated over a height profile in order to assess growth impact variability within individual trees. Growth reductions at the two sites closest the wellhead were statistically significant for five post-blowout years. Growth at these condensate impacted sites was reduced to 9.8% and 38.1% in 1983. Differences in growth reductions reflect a gradient of effects and a dose-response relationship. Recovery of surviving trees has been rapid but is leveling off at approximately 80% of pre-blowout growth. growth reductions were greater and recovery rates slower than those previously predicted by other authors. Statistically significant differences in height profile growth responses were limited to the upper portions of the trees. Growth rates over a tree height profile ranged from 10% less to 50% more than growth rates observed at a 1.3 metres. Analytical methodologies detected and described growth differences over a height profile but a larger sample size was desirable. As is always the case in catastrophic events, obtaining pre-event baseline data is often difficult. Dendrochronological methods described in this paper offer techniques for determining pre-blowout growth and monitoring impacts and recovery in forested areas

  20. Ecological response of Cedrus atlantica to climate variability in the Massif of Guetiane (Algeria

    Directory of Open Access Journals (Sweden)

    Said Slimani

    2014-12-01

    Full Text Available Aim of the study: The study analyzes the long-term response of Atlas cedar, Cedrus atlantica (Manneti, to climate variability. Area of study: Atlas cedar forest of Guetiane (Batna, Algeria.Material and methods: The dendrochronological approach was adopted. An Atlas cedar tree-ring chronology was established from twenty trees. The response of the species to climate variability was assessed through the pointer years (PYs, the common climate signal among the individual chronologies, expressed by the first component (PC1, the mean sensitivity (msx, and response function and correlations analysis involving the tree-ring index and climate data (monthly mean temperature and total precipitation.Results: The highest growth variability was registered from the second half of the 20th century. The lower than the mean PYs, the PC1, and the msx increased markedly during the studied period. Dramatic increases in the PC1 and msx were detected at the end of the 1970s, reflecting a shift towards drier conditions enhancing an increasing trend towards more synchronous response of trees to climate conditions. The response function and correlations analysis showed that tree growth was mainly influenced by precipitation variability.Research highlights: Our findings provide baseline knowledge concerning the ecological response of Atlas cedar to climate variability in in its southern distribution limit, where a high level of tree mortality has been observed during recent decades, coinciding with the driest period Algeria has ever experienced. This information is vital to support ongoing ecosystem management efforts in the region. Keywords: Atlas cedar; annual growth variability; dieback; dendrochronology

  1. Increased tree establishment in Lithuanian peat bogs--insights from field and remotely sensed approaches.

    Science.gov (United States)

    Edvardsson, Johannes; Šimanauskienė, Rasa; Taminskas, Julius; Baužienė, Ieva; Stoffel, Markus

    2015-02-01

    Over the past century an ongoing establishment of Scots pine (Pinus sylvestris L.), sometimes at accelerating rates, is noted at three studied Lithuanian peat bogs, namely Kerėplis, Rėkyva and Aukštumala, all representing different degrees of tree coverage and geographic settings. Present establishment rates seem to depend on tree density on the bog surface and are most significant at sparsely covered sites where about three-fourth of the trees have established since the mid-1990s, whereas the initial establishment in general was during the early to mid-19th century. Three methods were used to detect, compare and describe tree establishment: (1) tree counts in small plots, (2) dendrochronological dating of bog pine trees, and (3) interpretation of aerial photographs and historical maps of the study areas. In combination, the different approaches provide complimentary information but also weigh up each other's drawbacks. Tree counts in plots provided a reasonable overview of age class distributions and enabled capturing of the most recently established trees with ages less than 50 years. The dendrochronological analysis yielded accurate tree ages and a good temporal resolution of long-term changes. Tree establishment and spread interpreted from aerial photographs and historical maps provided a good overview of tree spread and total affected area. It also helped to verify the results obtained with the other methods and an upscaling of findings to the entire peat bogs. The ongoing spread of trees in predominantly undisturbed peat bogs is related to warmer and/or drier climatic conditions, and to a minor degree to land-use changes. Our results therefore provide valuable insights into vegetation changes in peat bogs, also with respect to bog response to ongoing and future climatic changes. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Dating a composite ancient wooden artefact and its modifications. A case study

    International Nuclear Information System (INIS)

    Poldi, G.; Quartana, L.; Galli, A.

    2008-01-01

    The recent restoration of the large wooden doors of the medieval St. Ambrogio Basilica in Milan gave the opportunity for a, broad project of scientific examination, including dating with radiocarbon and dendrochronology. The two doors represented a puzzle for art historians, because of the non-documented modifications occurred during their history. In fact; they are composed of various wooden elements, some of them surely modified with the 1750 jubilee restoration, assembled into three layers. The large number of these elements suggested not to restrict the samples only to the main carved scenes, but to extend them to frames and back-boards, in order to obtain a consistent set. of data, and a more reliable chronology. Analytical campaign oriented to dating, coordinated by Quartana Restauri and LAM (University of Bergamo), took into account the different characteristics of woods, needing 24 samples carefully extracted from hidden areas to be radiocarbon dated by ANIS (Accelerator Mass Spectrometry) at CEDAD (Centre for Dating and Diagnostics, University of Salento, Lecce, Italy) laboratories, and two of them dated at LABEC (Laboratory of nuclear techniques for cultural heritage, University of Florence and INFN, Italy) for comparison. The results obtained for the vertical woods of the back, belonging to Renaissance period, suggested further studies employing dendrochronological analyses based on high-resolution photographs, carried out by CUDaM (University of Milano-Bicocca). ED-XRF (Energy Dispersive X-ray Fluorescence) analyses were also carried on, by LAM, with portable instruments. in order to study the composition of the residues of polychromy, where present.

  3. Warm season precipitation signal in δ2 H values of wood lignin methoxyl groups from high elevation larch trees in Switzerland.

    Science.gov (United States)

    Riechelmann, Dana F C; Greule, Markus; Siegwolf, Rolf T W; Anhäuser, Tobias; Esper, Jan; Keppler, Frank

    2017-10-15

    In this study, we tested stable hydrogen isotope ratios of wood lignin methoxyl groups (δ 2 H methoxyl values) as a palaeoclimate proxy in dendrochronology. This is a quite new method in the field of dendrochronology and the sample preparation is much simpler than the methods used before to measure δ 2 H values from wood. We measured δ 2 H methoxyl values in high elevation larch trees (Larix decidua Mill.) from Simplon Valley (southern Switzerland). Thirty-seven larch trees were sampled and five individuals analysed for their δ 2 H methoxyl values at annual (1971-2009) and pentadal resolution (1746-2009). The δ 2 H methoxyl values were measured as CH 3 I released upon treatment of the dried wood samples with hydroiodic acid. 10-90 μL from the head-space were injected into the gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/HTC-IRMS) system. Testing the climate response of the δ 2 H methoxyl values, the annually resolved series show a positive correlation of r = 0.60 with June/July precipitation. The pentadally resolved δ 2 H methoxyl series do not show any significant correlation to climate parameters. Increased precipitation during June and July, which are on average warm and relatively dry months, results in higher δ 2 H values of the xylem water and, therefore, higher δ 2 H values in the lignin methoxyl groups. Therefore, we suggest that δ 2 H methoxyl values of high elevation larch trees might serve as a summer precipitation proxy. Copyright © 2017 John Wiley & Sons, Ltd.

  4. Fir Decline and Mortality in the Southern Siberian Mountains

    Science.gov (United States)

    Kharuk, Viacheslav I.; Im, Sergei T.; Petrov, Ilya A.; Dvinskaya, Mariya, L.; Fedotova, Elena V.; Ranson, Kenneth J.

    2016-01-01

    Increased dieback and mortality of dark needle conifer (DNC) stands (composed of fir (Abies sibirica),Siberian pine (Pinus sibirica) and spruce (Picea obovata))were documented in Russia during recent decades. Here we analyzed spatial and temporal patterns of fir decline and mortality in the southern Siberian Mountains based on satellite, in situ and dendrochronological data. The studied stands are located within the boundary between DNC taiga to the north and forest-steppe to the south. Fir decline and mortality were observed to originate where topographic features contributed to maximal water-stress risk, i.e., steep (1825),convex, south-facing slopes with a shallow well-drained root zone. Fir regeneration survived droughts and increased stem radial growth, while upper canopy trees died. Tree ring width(TRW) growth negatively correlated with vapor pressure deficit (VPD), drought index and occurrence of late frosts, and positively with soil water content. Previous year growth conditions (i.e., drought index, VPD, soil water anomalies)have a high impact on current TRW (r 0.600.74). Fir mortality was induced by increased water stress and severe droughts (as a primary factor) in synergy with bark-beetles and fungi attacks (as secondary factors). Dendrochronology data indicated that fir mortality is a periodic process. In a future climate with increased aridity and drought frequency, fir (and Siberian pine) may disappear from portions of its current range (primarily within the boundary with the forest steppe)and is likely to be replaced by drought-tolerant species such as Pinus sylvestris and Larix sibirica.

  5. Annual increments of juniper dwarf shrubs above the tree line on the central Tibetan Plateau: a useful climatic proxy

    Science.gov (United States)

    Liang, Eryuan; Lu, Xiaoming; Ren, Ping; Li, Xiaoxia; Zhu, Liping; Eckstein, Dieter

    2012-01-01

    Background and Aims Dendroclimatology is playing an important role in understanding past climatic changes on the Tibetan Plateau. Forests, however, are mainly confined to the eastern Tibetan Plateau. On the central Tibetan Plateau, in contrast, shrubs and dwarf shrubs need to be studied instead of trees as a source of climate information. The objectives of this study were to check the dendrochronological potential of the dwarf shrub Wilson juniper (Juniperus pingii var. wilsonii) growing from 4740 to 4780 m a.s.l. and to identify the climatic factors controlling its radial growth. Methods Forty-three discs from 33 stems of Wilson juniper were sampled near the north-eastern shore of the Nam Co (Heavenly Lake). Cross-dating was performed along two directions of each stem, avoiding the compression-wood side as far as possible. A ring-width chronology was developed after a negative exponential function or a straight line of any slope had been fit to the raw measurements. Then, correlations were calculated between the standard ring-width chronology and monthly climate data recorded by a weather station around 100 km away. Key Results Our study has shown high dendrochronological potential of Wilson juniper, based on its longevity (one individual was 324 years old), well-defined growth rings, reliable cross-dating between individuals and distinct climatic signals reflected by the ring-width variability. Unlike dwarf shrubs in the circum-arctic tundra ecosystem which positively responded to above-average temperature in the growing season, moisture turned out to be growth limiting for Wilson juniper, particularly the loss of moisture caused by high maximum temperatures in May–June. Conclusions Because of the wide distribution of shrub and dwarf shrub species on the central Tibetan Plateau, an exciting prospect was opened up to extend the presently existing tree-ring networks far up into one of the largest tundra regions of the world. PMID:22210848

  6. Different parts, different stories: climate sensitivity of growth is stronger in root collars vs. stems in tundra shrubs.

    Science.gov (United States)

    Ropars, Pascale; Angers-Blondin, Sandra; Gagnon, Marianne; Myers-Smith, Isla H; Lévesque, Esther; Boudreau, Stéphane

    2017-08-01

    Shrub densification has been widely reported across the circumpolar arctic and subarctic biomes in recent years. Long-term analyses based on dendrochronological techniques applied to shrubs have linked this phenomenon to climate change. However, the multi-stemmed structure of shrubs makes them difficult to sample and therefore leads to non-uniform sampling protocols among shrub ecologists, who will favor either root collars or stems to conduct dendrochronological analyses. Through a comparative study of the use of root collars and stems of Betula glandulosa, a common North American shrub species, we evaluated the relative sensitivity of each plant part to climate variables and assessed whether this sensitivity is consistent across three different types of environments in northwestern Québec, Canada (terrace, hilltop and snowbed). We found that root collars had greater sensitivity to climate than stems and that these differences were maintained across the three types of environments. Growth at the root collar was best explained by spring precipitation and summer temperature, whereas stem growth showed weak and inconsistent responses to climate variables. Moreover, sensitivity to climate was not consistent among plant parts, as individuals having climate-sensitive root collars did not tend to have climate-sensitive stems. These differences in sensitivity of shrub parts to climate highlight the complexity of resource allocation in multi-stemmed plants. Whereas stem initiation and growth are driven by microenvironmental variables such as light availability and competition, root collars integrate the growth of all plant parts instead, rendering them less affected by mechanisms such as competition and more responsive to signals of global change. Although further investigations are required to determine the degree to which these findings are generalizable across the tundra biome, our results indicate that consistency and caution in the choice of plant parts are a key

  7. Annual increments of juniper dwarf shrubs above the tree line on the central Tibetan Plateau: a useful climatic proxy.

    Science.gov (United States)

    Liang, Eryuan; Lu, Xiaoming; Ren, Ping; Li, Xiaoxia; Zhu, Liping; Eckstein, Dieter

    2012-03-01

    Dendroclimatology is playing an important role in understanding past climatic changes on the Tibetan Plateau. Forests, however, are mainly confined to the eastern Tibetan Plateau. On the central Tibetan Plateau, in contrast, shrubs and dwarf shrubs need to be studied instead of trees as a source of climate information. The objectives of this study were to check the dendrochronological potential of the dwarf shrub Wilson juniper (Juniperus pingii var. wilsonii) growing from 4740 to 4780 m a.s.l. and to identify the climatic factors controlling its radial growth. Forty-three discs from 33 stems of Wilson juniper were sampled near the north-eastern shore of the Nam Co (Heavenly Lake). Cross-dating was performed along two directions of each stem, avoiding the compression-wood side as far as possible. A ring-width chronology was developed after a negative exponential function or a straight line of any slope had been fit to the raw measurements. Then, correlations were calculated between the standard ring-width chronology and monthly climate data recorded by a weather station around 100 km away. Our study has shown high dendrochronological potential of Wilson juniper, based on its longevity (one individual was 324 years old), well-defined growth rings, reliable cross-dating between individuals and distinct climatic signals reflected by the ring-width variability. Unlike dwarf shrubs in the circum-arctic tundra ecosystem which positively responded to above-average temperature in the growing season, moisture turned out to be growth limiting for Wilson juniper, particularly the loss of moisture caused by high maximum temperatures in May-June. Because of the wide distribution of shrub and dwarf shrub species on the central Tibetan Plateau, an exciting prospect was opened up to extend the presently existing tree-ring networks far up into one of the largest tundra regions of the world.

  8. Longevity and growth of Acacia tortilis; insights from 14C content and anatomy of wood.

    Science.gov (United States)

    Andersen, Gidske L; Krzywinski, Knut

    2007-06-15

    Acacia tortilis is a keystone species across arid ecosystems in Africa and the Middle East. Yet, its life-history, longevity and growth are poorly known, and consequently ongoing changes in tree populations cannot be managed in an appropriate manner. In other arid areas parenchymatic bands marking growth zones in the wood have made dendrochronological studies possible. The possibilities for using pre- and post-bomb 14C content in wood samples along with the presence of narrow marginal parenchymatic bands in the wood is therefore tested to gain further insight into the age, growth and growth conditions of A. tortilis in the hyper-arid Eastern Desert of Egypt. Based on age scenarios and the Gompertz growth equation, the age of trees studied seems to be from 200 up to 650 years. Annual radial growth estimated from calibrated dates based on the post-bomb 14C content of samples is up to 2.4 mm, but varies both spatially and temporally. Parenchymatic bands are not formed regularly. The correlation in band pattern among trees is poor, both among and within sites. The post-bomb 14C content of A. tortilis wood gives valuable information on tree growth and is required to assess the age scenario approach applied here. This approach indicates high longevities and slow growth of trees. Special management measures should therefore be taken at sites where the trend in tree population size is negative. The possibilities for dendrochronological studies based on A. tortilis from the Eastern Desert are poor. However, marginal parenchymatic bands can give insight into fine scale variation in growth conditions and the past management of trees.

  9. Longevity and growth of Acacia tortilis; insights from 14C content and anatomy of wood

    Directory of Open Access Journals (Sweden)

    Krzywinski Knut

    2007-06-01

    Full Text Available Abstract Background Acacia tortilis is a keystone species across arid ecosystems in Africa and the Middle East. Yet, its life-history, longevity and growth are poorly known, and consequently ongoing changes in tree populations cannot be managed in an appropriate manner. In other arid areas parenchymatic bands marking growth zones in the wood have made dendrochronological studies possible. The possibilities for using pre- and post-bomb 14C content in wood samples along with the presence of narrow marginal parenchymatic bands in the wood is therefore tested to gain further insight into the age, growth and growth conditions of A. tortilis in the hyper-arid Eastern Desert of Egypt. Results Based on age scenarios and the Gompertz growth equation, the age of trees studied seems to be from 200 up to 650 years. Annual radial growth estimated from calibrated dates based on the post-bomb 14C content of samples is up to 2.4 mm, but varies both spatially and temporally. Parenchymatic bands are not formed regularly. The correlation in band pattern among trees is poor, both among and within sites. Conclusion The post-bomb 14C content of A. tortilis wood gives valuable information on tree growth and is required to assess the age scenario approach applied here. This approach indicates high longevities and slow growth of trees. Special management measures should therefore be taken at sites where the trend in tree population size is negative. The possibilities for dendrochronological studies based on A. tortilis from the Eastern Desert are poor. However, marginal parenchymatic bands can give insight into fine scale variation in growth conditions and the past management of trees.

  10. Oil sands terrestrial habitat and risk modeling for disturbance and reclamation - Phase I report

    Energy Technology Data Exchange (ETDEWEB)

    Welham, C. [FORRx Consulting Inc., Belcarra, BC (Canada)

    2010-11-15

    The main purpose of this study is to build a framework that includes risk management and strategic decision-making to assess the impact of natural and industrial disturbance on ecosystem products and services and on the existence of habitat for terrestrial species in Alberta's Lower Athabasca planning region. This will include an evaluation of the impact of disturbance, conservation and reclamation activities associated with oil sands development both at the lease and regional levels. The basecase scenario, established in Phase I, includes a dendrochronology study of the link between climate and tree growth in the sub boreal region that comprises oil sands mining, an analysis of habitat availability for 10 wildlife species compared with reclamation activities on the Kearl Lake mine, and an examination of the potential for development of high levels of water stress in recent reclamation plantations at the Kearl Lake mine. Four tree species of the subboreal forests of Alberta and Saskatchewan were considered for the dendrochronology study: the white spruce or Picea glauca, the black spruce or Picea mariana, the jack pine or Pinus banksiana, and the trembling aspen or Populus tremuloides. This study shows that the water stress observed during the year has restricted the radial growth of white spruce and a link has been established between radial growth and increasing season precipitation and summer temperatures. The purposes of the habitat suitability analysis were to list habitats suitability models that could be applied to Alberta boreal forests, distinguish the parameters used in those models that can be simulated with an ecosystem simulation model, simulate the reclamation prescriptions detailed in the Kearl Lake EIA documents with the ecosystem simulation model and generate output suitable for populating each habitat suitability model. The establishment of ecologically viable reclamation plans in the oil sands region can be hard to manage regarding the

  11. Growth-Climate Response of Young Turkey Oak (Quercus cerris L. Coppice Forest Stands along Longitudinal Gradient in Albania

    Directory of Open Access Journals (Sweden)

    Merita Stafasani

    2015-06-01

    Full Text Available Background and Purpose: Turkey oak (Quercus cerris L. is the most widespread species in Albania and less investigated from dendroclimatological point of view. Previous studies have reported that Q. cerris is sensitive to the environment when growing at different latitudes and ecological conditions. Based on this fact we have explored the response of different Q. cerris populations located along the longitudinal gradient. Materials and Methods: The stem discs were sampled from six sites (Kukes, Diber, Rreshen, Ulez, Elbasan, Belsh along longitudinal gradient ranging from north-east to central Albania. All oak forests stands grow under the influence of specific local Mediterranean climate. Tree-ring widths were measured to the nearest 0.001 mm using a linear table, LINTAB and the TSAP-Win program. Following the standard dendrochronological procedures residual tree-ring width chronologies were built for each site. Statistical parameters commonly used in dendrochronology were calculated for each site chronology. Relations between the tree-ring chronologies were explored using Hierarchical Factor Classification (HFC and Principal Component Analysis (PCA, while the radial growth-climate relationship was analyzed through correlation analysis using a 19-month window from April in the year prior to tree-ring formation (year t - 1 until October in the year of growth (year t. Results and Conclusions: The length of the site chronologies ranged from 16 to 36 years, with the Elbasan site chronology being the longest and the Belsh site chronology the shortest one. Trees at lower elevation were younger than trees at higher elevation. Statistical parameters (mean sensitivity (MS and auto correlation (AC of site chronologies were different among them and lower values of AC1 showed a weaker dependence of radial growth from climatic conditions of the previous growing year. Principal component analysis showed that Belsh, Rreshen and Elbasan site chronologies were

  12. Recent formation of arroyos in the Little Missouri Badlands of southwestern North Dakota

    Science.gov (United States)

    Gonzalez, M.A.

    2001-01-01

    In the Little Missouri Badlands of southwestern North Dakota, the channels of ephemeral streams are incised 2 to 10 m or more into mid-to-late Holocene alluvium. The objectives of this study were to determine the timing and cause(s) of the most recent episodes of fluvial incision and to develop a process-response model that illustrates the formation and evolution of arroyos in this region. The purpose was to distinguish natural from anthropogenic changes to the landscape and to discriminate allogenic from autogenic causes of incision, thereby gaining a greater sense of how steep, relatively small, ephemeral streams evolve. Dendrochronologic and dendrogeomorphic analyses of riparian cottonwoods provide an inexpensive, high-resolution dating method to constrain the time of incision, thereby permitting determination of the cause(s) of incision by evaluating environmental conditions prior to and at the onset of fluvial incision. An examination of seven small (10 to 100 km2) drainage basins indicated ephemeral streams have undergone a four-stage cycle of change within the past 200 years, comprising(i) an initial period of relative geomorphic stability with pedogenesis on the flood plain and low rates of lateral channel migration, (ii) a period of channel incision with subsequent widening of the flood plain through lateral corrasion along middle and upstream reaches, (iii) a concomitant period of aggradation along downstream reaches and, finally, (iv) a period of downstream incision. Dendrochronologic data and dendrogeomorphic relations indicate there have been three distinct periods of fluvial incision in the past 200 years. The first period of incision began in the 1860s and 1870s prior to the onset of European settlement and intensive grazing by domesticated cattle in the area. This period of incision occurred along the middle reaches of all seven of the streams examined and coincided with a severe, protracted drought, suggesting an allogenic cause. The second period

  13. Spatial analysis of charcoal kiln remains in the former royal forest district Tauer (Lower Lusatia, North German Lowlands)

    Science.gov (United States)

    Raab, Alexandra; Schneider, Anna; Bonhage, Alexander; Takla, Melanie; Hirsch, Florian; Müller, Frank; Rösler, Horst; Heußner, Karl-Uwe

    2016-04-01

    available as part of the ArcGis 10.1 spatial statistics toolbox. The outcomes are discussed in consideration of our archaeological, archival and dendrochronological research results. Raab, A., Takla, M., Raab, T., Nicolay, A., Schneider, A., Rösler, H., et al. (2015). Pre-industrial charcoal production in Lower Lusatia (Brandenburg, Germany): Detection and evaluation of a large charcoal-burning field by combining archaeological studies, GIS-based analyses of shaded-relief maps and dendrochronological age determination. Quaternary International, doi:http://dx.doi.org/10.1016/j.quaint.2014.09.041.

  14. Variations in the Sensitivity of Shrub Growth to Climate Change along Arctic Environmental and Biotic Gradients

    Science.gov (United States)

    Beck, P. S. A.; Myers-Smith, I. H.; Elmendorf, S.; Georges, D.

    2015-12-01

    Despite evidence of rapid shrub expansion at many Arctic sites and the profound effects this has on ecosystem structure, biogeochemical cycling, and land-atmosphere feedbacks in the Arctic, the drivers of shrub growth remain poorly understood. The compilation of 41,576 annual shrub growth measurements made around the Arctic, allowed for the first systematic evaluation of the climate sensitivity of Arctic shrub growth, i.e. the strength of the relationship between annual shrub growth and monthly climate variables. The growth measurements were taken on 1821 plants of 25 species at 37 arctic and alpine sites, either as annual ring widths or as stem increments. We evaluated climate sensitivity of shrub growth for each genus-by-site combination in this data set based on the performance and parameters of linear mixed models that used CRU TS3.21 climate data as predictors of shrub growth between 1950 and 2010. 76% of genus-by-site combinations showed climate sensitive growth, but climate-growth relationships varied with soil moisture, species canopy height, and geographic position within the species ranges. Shrubs growing at sites with more soil moisture showed greater climate sensitivity, suggesting that water availability might limit shrub growth if continued warming isn't matched by a steady increase in soil moisture. Tall shrub species growing at their northern range limit were particularly climate sensitive causing climate sensitivity of shrubs to peak at the transition between Low and High Arctic, where carbon storage in permafrost is greatest. Local and regional studies have documented matching spatial and temporal patterns in dendrochronological measurements and satellite observations of vegetation indices both in boreal and Arctic regions. Yet the circumarctic comparison of patterns in dendrochronological and remote sensing data sets yielded poor levels of agreement. In much of the Arctic, steep environmental gradients generate fine spatial patterns of vegetation

  15. A Model of Beaver Meadow Complex Evolution in the Silvies River Basin, Oregon.

    Science.gov (United States)

    Nash, C.; Grant, G.; Campbell, S. D.

    2014-12-01

    There is increasing evidence to suggest that the pervasive incision seen in the American West is due, in part, to the removal of beaver (Castor canadensis) in the first half of the 19th century. New restoration strategies for these systems focus on the reintroduction of beaver and construction of beaver dam analogs. Such dams locally raise streams beds and water tables, reconnect incised channels to their former floodplains, trap sediment, increase hydraulic diversity, and promote riparian vegetation. However, the geomorphic and hydrologic impacts of both the original beaver dams and their analogs are poorly understood. Observations in the Silvies River basin in Oregon, USA - an upland, semi-arid catchment with extremely high historic beaver populations and a presently recovering population, inform a conceptual model for valley floor evolution with beaver dams. The evolution of the beaver dam complex is characterized by eight stages of morphologic adjustment: water impoundment, sediment deposition, pond filling, multi-thread meadow creation, dam breaching, channel incision, channel widening, and floodplain development. Well-constructed beaver dams, given sufficient time and sediment flux, will evolve from a series of ponds to a multi-threaded channel flowing through a wet meadow complex. If a dam in the system fails, due to overtopping, undercutting, lack of maintenance, or abandonment, the upstream channel will concentrate into a single channel and incise, followed over time by widening once critical bank heights are exceeded. From stratigraphic, dendrochronologic, and geomorphic measurements, we are constraining average timescales associated with each stage's duration and transitional period. Measured sedimentation rates behind modern beaver dam analogs on five stream systems permit calculation of sediment flux over recent time periods, and aid in developing regional rates of sediment deposition over a range of drainage areas and gradients. Stratigraphic and

  16. Seasonal Climate Signals in Multiple Tree-Ring Parameters: A Pilot Study of Pinus ponderosa in the Columbia River Basin

    Science.gov (United States)

    Dannenberg, M.; Wise, E. K.; Keung, J. H.

    2014-12-01

    Proxy-based reconstructions of past climate have played an integral role in assessments of historical climate change, and tree-ring widths (TRW) have a long history of use in this paleoclimate research due to their annual resolution, widespread availability, and sensitivity of growth processes to variation in temperature and water availability. Increasingly, studies have shown that additional tree-ring metrics—including earlywood and latewood widths (EW and LW, respectively), maximum latewood density, and the intensity of reflected blue light from latewood (BI)—can provide additional information on seasonal climatic variability that is not present in TRW alone due to different processes that affect growth in different parts of the growing season. Studies of these additional tree-ring metrics highlight their utility in climate reconstructions, but to date they have mostly been limited to a few tree species and regions. Here, we extend the range of previous studies on alternative tree-ring metrics by evaluating the seasonal climate signals in TRW, EW, LW, and BI of Pinus ponderosa at six semiarid sites surrounding the Columbia River basin in the U.S. Pacific Northwest (PNW). Cores from each site were cross-dated and EW, LW, and TRW were measured using standard dendrochronological procedures. BI was obtained using a high-resolution flatbed scanner and CooRecorder software. To evaluate the unique climate processes and seasonalities contributing to different dendrochronological metrics, monthly temperature and precipitation from each site were obtained from the PRISM climate model and were correlated with each of the tree-ring metrics using the MATLAB program SEASCORR. We also evaluate the potential of using multiple tree-ring metrics (rather than a single proxy) in reconstructions of precipitation in the PNW. Initial results suggest that 1) tree growth at each site is water-limited but with substantial differences among the sites in the strength and seasonality of

  17. The nuclear bomb carbon curve recorded in tree-rings and lake sediments near Taal Volcano, Central Philippines

    Science.gov (United States)

    Liou, M. S.; Li, H. C.; Huang, S. K.; Guan, B. T.

    2017-12-01

    Dendrochronologies built from precisely dated annual rings have shown to record the regional bomb pulse and the C-14 concentration variations caused by local events. In this study, we collected teak trees Tectona grandis near the Lake Taal, Central Philippines in 2011 for dendrochronological analysis and radiocarbon dating. The tree-ring sample contains 90 rings dated from 1922 to 2011. Currently, 28 selected subsamples have been measured by AMS 14C on bulk carbon with a few samples on holocellulose. The 14C results of the samples indicate that: 1) the results of AMS 14C dating between holocellulose and whole wood from the same ring are similar, so we select whole wood for AMS 14C dating. 2) The nuclear bomb 14C pulse was clearly recorded in the Tectona grandis growth rings. The Δ14C values rose dramatically in 1960 and reached a maximum of 692‰ in 1966. The magnitude and the peak year of the bomb curve in the Tectona grandis tree-ring record are comparable to other published tree-ring records in the tropical regions. 3) The Δ14C values suddenly dropped in 1950, 1964 and 1968, probably affected by CO2 gas releasing due to the Taal volcanic activities. Further study on the tree-ring 14C dating will allow us to evaluate the bomb pulse trends more precisely, and the volcanic activities of Pinatubo and Taal Volcanoes. The tree-ring Δ14C record not only confirms existence of the bomb curve in Taal Lake area, but also allows us compare to the Δ14C record in the lake sediment for chronological construction. A 120-cm gravity core, TLS-2, collected from Lake Taal in 2008, shows the nuclear bomb carbon curve in the TOC of the core. However, the magnitude of the nuclear bomb 14C pulse in the TOC of TLS-2 is much lower than that in the tree-ring records, due to mixing effect of different organic carbon sources, smoothing effect of 14CO2 in multiple years plant growths, local old CO2 emission from volcanic activity, degassing from the lake bottom, and industrial and city

  18. Missing rings in Pinus halepensis – the missing link to relate the tree-ring record to extreme climatic events

    Directory of Open Access Journals (Sweden)

    Klemen eNovak

    2016-05-01

    Full Text Available Climate predictions for the Mediterranean Basin include increased temperatures, decreased precipitation, and increased frequency of extreme climatic events (ECE. These conditions are associated with decreased growth of trees and their increased vulnerability to pests and diseases. The anatomy of tree rings is responsive to these environmental conditions. Quantitatively, the width of a tree ring is largely determined by the rate and duration of cell division by the vascular cambium. In the Mediterranean climate, cambial cell division may occur throughout almost the entire year. Alternatively, cell division may stop during relatively cool and dry winters, only to resume in the same year with milder temperatures and increased availability of water. Under particularly adverse conditions, no xylem may be produced in parts of the stem, resulting in a missing ring (MR, which can link tree-ring anatomy to the occurrence of extreme events. A dendrochronological network of Pinus halepensis, a widespread tree species in the Mediterranean basin, was used to determine the relationship of MR to ECE. The network consisted of 113 sites throughout its distribution range. Binomial logistic regression analysis of 2595 MR series determined that MR increased in frequency with increased cambial age. Spatial analysis indicated that the geographic areas of southeastern Spain and northern Algeria contained the greatest frequency of MR. Further regression analysis indicated that the relationship of MR to total monthly precipitation and mean temperature was non-linear. In this first determination of climatic influences on MR, the formation of MR was most strongly associated with the combination of monthly mean temperature above 10°C from previous October till current February and total precipitation below 50 mm from previous September till current May. This conclusion is global and can be applied to every site across the distribution area. Rather than simply being a

  19. Radiation densitometry in tree-ring analysis: a review and procedure manual

    Energy Technology Data Exchange (ETDEWEB)

    Parker, M.L.; Taylor, F.G.; Doyle, T.W.; Foster, B.E.; Cooper, C.; West, D.C.

    1985-01-01

    An x-ray densitometry of wood facility is being established by the Environmental Sciences Division, Oak Ridge Natioanl Laboratory (ORNL). The objective is to apply tree-ring data to determine whether or not there is a fertilizer effect on tree growth from increased atmospheric carbon dioxide since the beginning of the industrial era. Intra-ring width and density data, including ring-mass will be detemined from tree-ring samples collected from sites located throughout the United States and Canada. This report is designed as a guide to assist ORNL scientists in building the x-ray densitometry system. The history and development of x-ray densitometry in tree-ring research is examined and x-ray densitometry is compared with other techniques. Relative wood and tree characteristics are described as are environmental and genetic factors affecting tree growth responses. Methods in x-ray densitometry are examined in detail and the techniques used at four operating laboratories are described. Some ways that dendrochronology has been applied in dating, in wood quality, and environmental studies are presented, and a number of tree-ring studies in Canada are described. An annotated bibliography of radiation densitometry in tree-ring analysis and related subjects is included.

  20. CLIMATE-TREE GROWTH RELATIONSHIPS OF Mimosa tenuiflora IN SEASONALLY DRY TROPICAL FOREST, BRAZIL

    Directory of Open Access Journals (Sweden)

    Patrícia Póvoa Mattos

    2015-03-01

    Full Text Available Mimosa tenuiflora is a native pioneer tree from the Caatinga used commercially as firewood due to its high calorific value. It is deciduous, its trunk does not reach large diameters and it has good regrowth capacity. This study intended to determine the annual increment in diameter of M. tenuiflora and its correlation with rainfall, as basis for fuel wood management. Disks from the stem base of M. tenuiflora trees were collected in 2008 in Sertânia and Serra Talhada, Pernambuco State, from regrowth of trees coppiced in 2003 and in Limoeiro do Norte, Ceará State, from a plantation established in 2002. The trees have well-defined annual growth rings, highly correlated with annual precipitation and are well-suited for dendrochronological investigations. Forest managers must consider the influence of previous drier years in the wood production when predicting fuel wood harvesting. The high growth correlation with the previous year’s rainfall in regions where the rains start after photoperiodic stimulation indicate the necessity of understanding the growth dynamics of the species under dry forest conditions through additional ecophysiology studies.

  1. Carbon-14 in tree rings

    International Nuclear Information System (INIS)

    Cain, W.F.; Suess, H.E.

    1976-01-01

    In order to investigate how reliably the carbon 14 content of tree rings reflects that of atmospheric carbon dioxide, two types of determinations were carried out: (1) carbon 14 determinations in annual rings from the beginning of this century until 1974 and (2) carbon 14 determinations in synchronous wood from the North American bristlecone pine and from European oak trees, dendrochronologically dated to have grown in the third and fourth century B.C. The first series of measurements showed that bomb-produced radiocarbon was incorporated in wood at a time when it was converted from sapwood to heartwood, whenever radiocarbon from bomb testing was present in the atmosphere. The second series showed that wood more than 2000 years old and grown on two different continents at different altitudes had, within the limits of experimental error, the same radiocarbon content. This work and other experimental evidence, obtained in part by other laboratories, show that tree rings reflect the average radiocarbon content of global atmospheric carbon dioxide accurately within several parts per mil. In rare cases, deviations of up to 10 parts per thousand may be possible. This means that a typical single radiocarbon date for wood or charcoal possesses an intrinsic uncertainty (viz., an estimated ''one-sigma error'' in addition to all the other errors) of the order of +-50 years. This intrinsic uncertainty is independent of the absolute age of the sample. More accurate dates can, in principle, be obtained by the so-called method of ''wiggle matching.''

  2. Measurement of 14C time scale of the rings of a tree by accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Oda, Hirotaka; Furukawa, Michiaki; Yonenobu, Hitoshi; Ikeda, Akiko; Nakamura, Toshio.

    1996-01-01

    14 C time scale is different from a histrical data in order that it is calculated by assuming that the concentration of 14 C in the sample has not been changed by age. The object of this work is to make clear the errors in measurement of 14 C time scale of the ring of a tree known the tree age. The every year ring of a Hinoki in Kiso, 950 years old, was used as a sample. The most external ring is determined as 1923 years old on the basis of the dendrochronology. The rings after 1120 years were used as the samples. α-cellulose, the most stable component in the structural components of cell of tree, was prepared from each ring. About 8 mg of α-cellulose was reduced to graphite to be measured by the tandem thoron analytic meter. The results obtained showed that 14 C time scale was older than that of the histrical data in the twelfth and thirteenth century, but it was more new than that of the histrical data from the late seventeenth to the middle of eighteenth century. The results were agreement with that of Stuiver and Pearson (1933). (S.Y.)

  3. Paleoenvironmental and paleoclimatic investigations on Isla de los Estados, Argentina

    Science.gov (United States)

    Björck, S.; Fernandez, M.; Hjort, C.; Ljung, K.; Martinez, O.; Möller, P.; Ponce, F.; Rabassa, J.; Roig, F.; Unkel, I.; Wohlfarth, B.

    2007-05-01

    The expedition in November-December 2005 to Isla de los Estados (Staten Island) off the southeastern tip of South America was a cooperative venture between Lund University (LU) and Stockholm University (SU) in Sweden and the CADIC-CONICET Institute in Ushuaia, Argentina. The aim of the expedition was threefold: (1) to extend the Swedish paleoclimatic "ATLANTIS"-project (Greenland, Iceland, Faroe Islands, Azores, Grenada, Tristan da Cunha; PI S Björck) to the southern part of the South American continent, (2) to connect earlier glacial and climate history reconstructions from the Antarctic Peninsula to equivalents north of the Drake Passage in southernmost South America, and (3) to complement paleo-information available from the Tierra del Fuego mainland with information from Isla de los Estados. Focus was on two areas in the northern and north-western part of the island, Bahía Colnett and Bahia Crossley. Detailed geomorphologic and stratigraphic mapping of glacial deposits were combined with sampling sediments for OSL dating. To reconstruct the paleoclimatic development of Isla de los Estados since the last ice retreat, four main peat bog/lake sites were cored and sampled. In addition, living trees of Nothofagus and old logs preserved in the peat were sampled for dendrochronological and dendroclimatological studies. Preliminary results show that the deglaciation of the study area occurred before 16500 cal yr BP. Detailed multi- proxy analyses of the four sequences are under way and first results will be presented.

  4. Rock outcrops reduce temperature-induced stress for tropical conifer by decoupling regional climate in the semiarid environment.

    Science.gov (United States)

    Locosselli, Giuliano Maselli; Cardim, Ricardo Henrique; Ceccantini, Gregório

    2016-05-01

    We aimed to understand the effect of rock outcrops on the growth of Podocarpus lambertii within a microrefuge. Our hypothesis holds that the growth and survival of this species depend on the regional climate decoupling provided by rock outcrops. To test this hypothesis, we characterized the microclimate of (1) surrounding vegetation, (2) rock outcrop corridors, and (3) adjacencies. We assessed population structure by collecting data of specimen stem diameter and height. We also assessed differences between vegetation associated or not with outcrops using satellite imaging. For dendrochronological analyses, we sampled 42 individuals. Tree rings of 31 individuals were dated, and climate-growth relationships were tested. Rock outcrops produce a favorable microclimate by reducing average temperature by 4.9 °C and increasing average air humidity by 12 %. They also reduce the variability of atmospheric temperature by 42 % and air humidity by 20 % supporting a vegetation with higher leaf area index. Within this vegetation, specimen height was strongly constrained by the outcrop height. Although temperature and precipitation modulate this species growth, temperature-induced stress is the key limiting growth factor for this population of P. lambertii. We conclude that this species growth and survival depend on the presence of rock outcrops. These topography elements decouple regional climate in a favorable way for this species growth. However, these benefits are restricted to the areas sheltered by rock outcrops. Although this microrefuge supported P. lambertii growth so far, it is unclear whether this protection would be sufficient to withstand the stress of future climate changes.

  5. Implications of Liebig’s law of the minimum for tree-ring reconstructions of climate

    Science.gov (United States)

    Stine, A. R.; Huybers, P.

    2017-11-01

    A basic principle of ecology, known as Liebig’s Law of the Minimum, is that plant growth reflects the strongest limiting environmental factor. This principle implies that a limiting environmental factor can be inferred from historical growth and, in dendrochronology, such reconstruction is generally achieved by averaging collections of standardized tree-ring records. Averaging is optimal if growth reflects a single limiting factor and noise but not if growth also reflects locally variable stresses that intermittently limit growth. In this study a collection of Arctic tree ring records is shown to follow scaling relationships that are inconsistent with the signal-plus-noise model of tree growth but consistent with Liebig’s Law acting at the local level. Also consistent with law-of-the-minimum behavior is that reconstructions based on the least-stressed trees in a given year better-follow variations in temperature than typical approaches where all tree-ring records are averaged. Improvements in reconstruction skill occur across all frequencies, with the greatest increase at the lowest frequencies. More comprehensive statistical-ecological models of tree growth may offer further improvement in reconstruction skill.

  6. Influence of flow variability on floodplain formation and destruction, Little Missouri River, North Dakota

    Science.gov (United States)

    Miller, J.R.; Friedman, J.M.

    2009-01-01

    Resolving observations of channel change into separate planimetric measurements of floodplain formation and destruction reveals distinct relations between these processes and the flow regime. We analyzed a time sequence of eight bottomland images from 1939 to 2003 along the Little Missouri River, North Dakota, to relate geomorphic floodplain change to flow along this largely unregulated river. At the decadal scale, floodplain formation and destruction varied independently. Destruction was strongly positively correlated with the magnitude of infrequent high flows that recur every 5-10 yr, whereas floodplain formation was negatively correlated with the magnitude of frequent low flows exceeded 80% of the time. At the century scale, however, a climatically induced decrease in peak flows has reduced the destruction rate, limiting the area made available for floodplain formation. The rate of destruction was not uniform across the floodplain. Younger surfaces were consistently destroyed at a higher rate than older surfaces, suggesting that throughput of contaminants would have occurred more rapidly than predicted by models that assume uniform residence time of sediment across the floodplain. Maps of floodplain ages produced by analysis of sequential floodplain images are similar to maps of forest ages produced through dendrochronology, confirming the assumption of dendrogeomorphic studies that riparian tree establishment in this system is limited to recent channel locations. ?? 2009 Geological Society of America.

  7. 1600 AD Huaynaputina Eruption (Peru, Abrupt Cooling, and Epidemics in China and Korea

    Directory of Open Access Journals (Sweden)

    Jie Fei

    2016-01-01

    Full Text Available The 1600 AD Huaynaputina eruption in Peru was one of the largest volcanic eruptions in history over the past 2000 years. This study operated on the hypothesis that this event dramatically affected the weather and environment in China and the Korean Peninsula. Over the course of this research the Chinese and Korean historical literatures as well as dendrochronology records were examined. The historical evidence points to the conclusion that the eruption was followed by an abrupt cooling period and epidemic outbreaks in 1601 AD within both China and the Korean Peninsula. These records manifested themselves in unseasonably cold weather resulting in severe killing frosts in northern China in the summer and autumn of 1601 AD. In southern China (Zhejiang and Anhui Provinces and Shanghai Municipality, July was abnormally cold with snow, with an autumn that saw anomalously hot weather. In addition, there was unseasonable snowfall that autumn within Yunnan Province. Widespread disease outbreaks occurred in August, September, and October in northern and southern China. In Korea, the spring and early summer of 1601 AD were unusually cold, and conditions led to further widespread epidemics occurring in August.

  8. Studying global change through investigation of the plastic responses of xylem anatomy in tree rings.

    Science.gov (United States)

    Fonti, Patrick; von Arx, Georg; García-González, Ignacio; Eilmann, Britta; Sass-Klaassen, Ute; Gärtner, Holger; Eckstein, Dieter

    2010-01-01

    Variability in xylem anatomy is of interest to plant scientists because of the role water transport plays in plant performance and survival. Insights into plant adjustments to changing environmental conditions have mainly been obtained through structural and functional comparative studies between taxa or within taxa on contrasting sites or along environmental gradients. Yet, a gap exists regarding the study of hydraulic adjustments in response to environmental changes over the lifetimes of plants. In trees, dated tree-ring series are often exploited to reconstruct dynamics in ecological conditions, and recent work in which wood-anatomical variables have been used in dendrochronology has produced promising results. Environmental signals identified in water-conducting cells carry novel information reflecting changes in regional conditions and are mostly related to short, sub-annual intervals. Although the idea of investigating environmental signals through wood anatomical time series goes back to the 1960s, it is only recently that low-cost computerized image-analysis systems have enabled increased scientific output in this field. We believe that the study of tree-ring anatomy is emerging as a promising approach in tree biology and climate change research, particularly if complemented by physiological and ecological studies. This contribution presents the rationale, the potential, and the methodological challenges of this innovative approach.

  9. Traffic pollution affects tree-ring width and isotopic composition of Pinus pinea

    International Nuclear Information System (INIS)

    Battipaglia, Giovanna; Marzaioli, Fabio; Lubritto, Carmine; Altieri, Simona; Strumia, Sandro; Cherubini, Paolo; Cotrufo, M. Francesca

    2010-01-01

    This study presents new evidence that radiocarbon, combined with dendrochronological and stable isotopes analysis in tree rings and needles, can help to better understand the influence of pollution on trees. Pinus pinea individuals, adjacent to main roads in the urban area of Caserta (South Italy) and exposed to large amounts of traffic exhaust since 1980, were sampled and the time-related trend in the growth residuals was estimated. We found a consistent decrease in the ring width starting from 1980, with a slight increase in δ 13 C value, which was considered to be a consequence of environmental stress. No clear pattern was identified in δ 15 N, while an increasing effect of the fossil fuel dilution on the atmospheric bomb-enriched 14 C background was detected in tree rings, possibly as a consequence of the increase in traffic exhausts. Our findings suggested that radiocarbon is a very sensitive tool to investigate small-scale (i.e. traffic exhaust at the level crossing) and large-scale (urban area pollution) induced disturbances.

  10. Development of a C-14 detector and measurement of delta C-14 in dated tree rings grown in 1043 to 1055

    International Nuclear Information System (INIS)

    Oona, H.

    1979-01-01

    A proportional counter was constructed from plastic scintillator for measuring the C-14 contents in dendrochronologically dated tree ringas. The tree rings were individually converted to methane which, at one atmosphere pressure, was used as the counter gas. The wall, being a scintillator, serves as the 4π anti-coincidence shell for rejection of natural radioactivity in the material housing the proportional counter and penetrating cosmic ray muons. The output of the proportional counter, which is in anti-coincidence with the scintillation is recorded with a pulse height analyzer. After background subtraction, it yields the beta-decay spectrum of C-14 in the methane-filled proportional counter. The count rate obtained from the 5.5 liter effective volume counter for each year's sample is then referenced to a standard traceable to the National Bureau of Standards, and after corrections due to isotopic fracionation are applied, the ΔC-14 for each sample is determined. The fluctuations in the ΔC-14 are inspected, and used as an estimate for the energy content in the γ-ray burst of the Crab Nebula in 1054 A.D. Fluctuations due possibly to solar flares, neutron flux, cosmic ray muons, and sample preparation restrict the energy estimate to an upper limit of less than or equal to 10 50 ergs

  11. Contrasting environmental drivers of adult and juvenile growth in a marine fish: implications for the effects of climate change.

    Science.gov (United States)

    Ong, Joyce Jia Lin; Rountrey, Adam Nicholas; Meeuwig, Jessica Jane; Newman, Stephen John; Zinke, Jens; Meekan, Mark Gregory

    2015-06-08

    Many marine fishes have life history strategies that involve ontogenetic changes in the use of coastal habitats. Such ontogenetic shifts may place these species at particular risk from climate change, because the successive environments they inhabit can differ in the type, frequency and severity of changes related to global warming. We used a dendrochronology approach to examine the physical and biological drivers of growth of adult and juvenile mangrove jack (Lutjanus argentimaculatus) from tropical north-western Australia. Juveniles of this species inhabit estuarine environments and adults reside on coastal reefs. The Niño-4 index, a measure of the status of the El Niño-Southern Oscillation (ENSO) had the highest correlation with adult growth chronologies, with La Niña years (characterised by warmer temperatures and lower salinities) having positive impacts on growth. Atmospheric and oceanographic phenomena operating at ocean-basin scales seem to be important correlates of the processes driving growth in local coastal habitats. Conversely, terrestrial factors influencing precipitation and river runoff were positively correlated with the growth of juveniles in estuaries. Our results show that the impacts of climate change on these two life history stages are likely to be different, with implications for resilience and management of populations.

  12. Latest Pleistocene and Holocene glacial events in the Colonia valley, Northern Patagonia Icefield, southern Chile

    Science.gov (United States)

    Nimick, David A.; Mcgrath, Daniel; Mahan, Shannon; Friesen, Beverly A.; Leidich, Jonathan

    2016-01-01

    The Northern Patagonia Icefield (NPI) is the primary glaciated terrain worldwide at its latitude (46.5–47.5°S), and constraining its glacial history provides unique information for reconstructing Southern Hemisphere paleoclimate. The Colonia Glacier is the largest outlet glacier draining the eastern NPI. Ages were determined using dendrochronology, lichenometry, radiocarbon, cosmogenic 10Be and optically stimulated luminescence. Dated moraines in the Colonia valley defined advances at 13.2 ± 0.95, 11.0 ± 0.47 and 4.96 ± 0.21 ka, with the last being the first constraint on the onset of Neoglaciation for the eastern NPI from a directly dated landform. Dating in the tributary Cachet valley, which contains an ice-dammed lake during periods of Colonia Glacier expansion, defined an advance at ca. 2.95 ± 0.21 ka, periods of advancement at 810 ± 49 cal a BP and 245 ± 13 cal a BP, and retreat during the intervening periods. Recent Colonia Glacier thinning, which began in the late 1800s, opened a lower-elevation outlet channel for Lago Cachet Dos in ca. 1960. Our data provide the most comprehensive set of Latest Pleistocene and Holocene ages for a single NPI outlet glacier and expand previously developed NPI glacial chronologies.

  13. Annual reconstruction of the solar cycle from atmospheric 14C variations

    International Nuclear Information System (INIS)

    Murphy, J.O.

    1990-01-01

    Initially, the rise and fall components of the 11-year solar sunspot cycle are approximated by separate least-squares polynomials for four cycle classifications, which are determined by the magnitude of the average of the annual sunspot numbers per cycle. Following a method is formulated to generate detailed reconstruction of the annual variation of a solar cycle based on this cycle average, and the results obtained for cycles -4 through to 21 are compared with the annual Zurich values. This procedure is then employed to establish annual sunspot numbers using published average cycle values obtained from atmospheric carbon 14 variations, which have been derived from the chemical analysis of tree ring sections. The reconstructed sequences are correlated with the observed cycle values and with tree ring width index chronologies which exhibit a significant 11-year periodicity. It is anticipated that the long carbon 14 records and parallel dendrochronological data could be employed to obtain a more detailed portrayal of previous periods of strong solar activity than that given by current estimates based on historical records. 17 refs., 2 tabs., 9 figs

  14. Modelling growth-competition relationships in trembling aspen and white spruce mixed boreal forests of Western Canada.

    Science.gov (United States)

    Huang, Jian-Guo; Stadt, Kenneth J; Dawson, Andria; Comeau, Philip G

    2013-01-01

    We examined the effect of competition on stem growth of Picea glauca and Populus tremuloides in boreal mixedwood stands during the stem exclusion stage. We combined traditional approaches of collecting competition data with dendrochronology to provide retrospective measurements of stem diameter growth. Several competition indices including stand basal area (BA), the sum of stem diameter at breast height (SDBH), and density (N) for the broadleaf and coniferous species, as well as similar indices considering only trees with diameters greater than each subject (BAGR, SDBHGR, and NGR), were evaluated. We used a nonlinear mixed model to characterize the basal area increment over the past 5, 10, 15, 20, 25, 30, and 35 years as a function of growth of nearby dominant trees, the size of the subject trees, deciduous and coniferous competition indices, and ecoregions. SDBHGR and BAGR were better predictors for spruce, and SDBHGR and NGR were better for aspen, respectively, than other indices. Results showed strongest correlations with long-term stem growth, as the best models integrated growth for 10-25 years for aspen and ≥ 25 for spruce. Our model demonstrated a remarkable capability (adjusted R(2)>0.67) to represent this complex variation in growth as a function of site, size and competition.

  15. Tropical dendrochemistry: A novel approach to estimate age and growth from ringless trees

    International Nuclear Information System (INIS)

    Poussart, P.; Myneni, S.; Lanzirotti, A.

    2006-01-01

    Although tropical forests play an active role in the global carbon cycle and climate, their growth history remains poorly characterized compared to other ecosystems on the planet. Trees are prime candidates for the extraction of paleoclimate archives as they can be probed sub-annually, are widely distributed and can live for over 1400 years. However, dendrochronological techniques have found limited applications in the tropics because trees often lack visible growth rings. Alternative methods exist (dendrometry, radio- and stable isotopes), but the derived records are either of short-duration, lack seasonal resolution or are prohibitively labor intensive to produce. Here, we show the first X-ray microprobe synchrotron record of calcium (Ca) from a ringless Miliusa velutina tree from Thailand and use it to estimate the tree's age and growth history. The Ca age model agrees within (le)2 years of bomb-radiocarbon age estimates and confirms that the cycles are seasonal. The amplitude of the Ca annual cycle is correlated significantly with growth and annual Ca maxima correlate with the amount of dry season rainfall. Synchrotron measurements are fast and producing sufficient numbers of replicated multi-century tropical dendrochemical climate records now seems analytically feasible

  16. Variations of vessel diameter and δ13C in false rings of Arbutus unedo L. reflect different environmental conditions.

    Science.gov (United States)

    Battipaglia, Giovanna; De Micco, Veronica; Brand, Willi A; Linke, Petra; Aronne, Giovanna; Saurer, Matthias; Cherubini, Paolo

    2010-12-01

    Woody species in Mediterranean ecosystems form intra-annual density fluctuations (IADFs) in tree rings in response to changes in environmental conditions, especially water availability. Dendrochronology, quantitative wood anatomy and high-resolution isotopic analysis (using a laser ablation technique) were used to characterize IADFs in Arbutus unedo shrubs grown on two sites with different water availability on the island of Elba (Italy). Our findings show that IADF characterization can provide information about the relationship between environmental factors and tree growth at the seasonal level. At the more xeric site, IADFs mainly located in the early and middle parts of the annual ring, showed a decrease in vessel size and an increase in δ(13) C as a result of drought deficit. Opposite trends were found at the more mesic site, with IADFs located at the end of the ring and associated with a lower δ(13) C. Moreover, at the first site, IADFs are induced by drought deficit, while at the second site IADFs are linked with the regrowth in the last part of the growing season triggered by favourable wet conditions. This combined approach is a promising way for dating problematic wood samples and interpreting the phenomena that trigger the formation of IADFs in the Mediterranean environment. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).

  17. Connecting, synchronising, and dating with tephras : principles and applications of tephrochronology in Quaternary research

    International Nuclear Information System (INIS)

    Lowe, D.J.

    2016-01-01

    Tephrochronology is a unique method for linking and dating geological, palaeoecological, palaeoclimatic or archaeological sequences or events. The method relies firstly and fundamentally on stratigraphy and the law of superposition, which apply in any study that connects or correlates deposits from one place to another. Secondly, it relies on characterising and hence identifying or 'fingerprinting' tephra layers using either physical properties evident in the field or those obtained from laboratory analysis, including mineralogical examination by optical microscopy or geochemical analysis of glass shards or crystals (e.g. Fe-Ti oxides, ferromagnesian minerals) using the electron microprobe and other tools. Thirdly, the method is enhanced when a numerical age is obtained for a tephra layer by (1) radiometric methods such as radiocarbon, fission-track, U-series, or Ar/Ar dating, (2) incremental dating methods including dendrochronology or varved sediments or layering in ice cores, or (3) age-equivalent methods such as palaeomagnetism or correlation with marine oxygen isotope stages or palynostratigraphy. Once known, that age can be transferred from one site to the next using stratigraphic methods and by matching compositional characteristics, i.e. comparing 'fingerprints' from each layer. Used this way, tephrochronology is an age-equivalent dating method. (author).

  18. Climate variations and the enhanced greenhouse effect

    Energy Technology Data Exchange (ETDEWEB)

    Karlen, W. [Stockholm Univ. (Sweden). Dept. of Physical Geography

    1998-06-01

    Changes in the size of glaciers, in the altitude of the alpine tree-limit, and variation in the width of tree-rings during the Holocene clearly indicate that the average Scandinavian summer temperature has fluctuated. During warm periods it has been about 2 deg C warmer than at present; during cold periods it has been almost as cold as it was during the coldest decades of the previous centuries. Superimposed on these long-term variations, which have lasted from 100 to 200 years, are short fluctuations in temperature. The Scandinavian chronology, which is based on glacier and alpine tree-limit fluctuations as well as on dendrochronology, is well correlated with the changes in climate, which studies of ice cores from central Greenland have revealed. It is therefore believed that the Scandinavian climate chronology depicts conditions typical of a large area. The Scandinavian record is compared with data concerning solar irradiation variations estimated as {sup 14}C anomalies obtained from tree-rings. A correlation between major changes in climate and variations in solar irradiation points to a solar forcing of the climate. This means that there is no evidence of a human influence on climate so far Special issue. Research for mountain area development: Europe. 64 refs, 3 figs

  19. Analysis of contaminating elements in tree rings in Santiago, Chile

    International Nuclear Information System (INIS)

    Romo-Kroeger, C.M.; Avila, M.J.; Eaton, L.C.; Lopez, L.A.

    1996-01-01

    Using the 22'' isochronous cyclotron at the University of Chile, we have performed PIXE analyses on a group of samples collected from trees of metropolitan parks in Santiago. Dendrochronology was performed on each sample, which was then sectioned for the PIXE and other analyses, neutron activation and electro-chemistry. Available samples are trunk sections or cores obtained by the use of a 4.0 mm stainless steel incremental corer. We took three cores from each tree with permission of the municipalities. For the PIXE we use infinitely thick targets, as wood slabs taken along the trunk radius, and thin targets obtained by acid digestion of wood pieces and deposition on Kapton foils. Self supporting thick targets were placed directly in the PIXE chamber in a position so as to allow the irradiation of a specific annual ring. Potassium and Calcium appear as the most abundant elements in wood. Other elements such as S, Cu, Zn, As, Br and Pb were detected in amounts above the natural background in wood, and can be attributed to environmental contamination. The K/Ca ratios appear to be different for each species of tree, and seem to be related to the physico-chemical properties of wood. Preliminary results show important amounts of As and Cu (supposedly from mining origin) with increasing presence in the recent years. Pb and Zn (supposedly from vehicle origin) are also higher in recent years. (author)

  20. Soil moisture and its role in growth-climate relationships across an aridity gradient in semiarid Pinus halepensis forests.

    Science.gov (United States)

    Manrique-Alba, Àngela; Ruiz-Yanetti, Samantha; Moutahir, Hassane; Novak, Klemen; De Luis, Martin; Bellot, Juan

    2017-01-01

    In Mediterranean areas with limited availability of water, an accurate knowledge of growth response to hydrological variables could contribute to improving management and stability of forest resources. The main goal of this study is to assess the temporal dynamic of soil moisture to better understand the water-growth relationship of Pinus halepensis forests in semiarid areas. The estimates of modelled soil moisture and measured tree growth were used at four sites dominated by afforested Pinus halepensis Mill. in south-eastern Spain with 300 to 609mm mean annual precipitation. Firstly, dendrochronological samples were extracted and the widths of annual tree rings were measured to compute basal area increments (BAI). Secondly, soil moisture was estimated over 20 hydrological years (1992-2012) by means of the HYDROBAL ecohydrological model. Finally, the tree growth was linked, to mean monthly and seasonal temperature, precipitation and soil moisture. Results depict the effect of soil moisture on growth (BAI) and explain 69-73% of the variance in semiarid forests, but only 51% in the subhumid forests. This highlights the fact that that soil moisture is a suitable and promising variable to explain growth variations of afforested Pinus halepensis in semiarid conditions and useful for guiding adaptation plans to respond pro-actively to water-related global challenges. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Growth of a deep-water, predatory fish is influenced by the productivity of a boundary current system.

    Science.gov (United States)

    Nguyen, Hoang Minh; Rountrey, Adam N; Meeuwig, Jessica J; Coulson, Peter G; Feng, Ming; Newman, Stephen J; Waite, Anya M; Wakefield, Corey B; Meekan, Mark G

    2015-03-12

    The effects of climate change on predatory fishes in deep shelf areas are difficult to predict because complex processes may govern food availability and temperature at depth. We characterised the net impact of recent environmental changes on hapuku (Polyprion oxygeneios), an apex predator found in continental slope habitats (>200 m depth) by using dendrochronology techniques to develop a multi-decadal record of growth from otoliths. Fish were sampled off temperate south-western Australia, a region strongly influenced by the Leeuwin Current, a poleward-flowing, eastern boundary current. The common variance among individual growth records was relatively low (3.4%), but the otolith chronology was positively correlated (r = 0.61, p < 0.02) with sea level at Fremantle, a proxy for the strength of the Leeuwin Current. The Leeuwin Current influences the primary productivity of shelf ecosystems, with a strong current favouring growth in hapuku. Leeuwin Current strength is predicted to decline under climate change models and this study provides evidence that associated productivity changes may flow through to higher trophic levels even in deep water habitats.

  2. Reconstruction and analysis of the past five centuries of streamflow on northern slopes on Tianshan Mountains in Northern Xinjiang, China

    Science.gov (United States)

    Yang, Yuhui; Chen, Yaning; Wang, Minzhong; Sun, Huilan

    2017-07-01

    We examined the changes in streamflow on the northern slopes of the Tianshan Mountains in northern Xinjiang, China, over two time scales: the past 500 years, based on dendrochronology data; and the past 50 years, based on streamflow data from hydrological stations. The method of artificial neural networks built from the data of the 50-year period was used to reconstruct the streamflow of the 500-year period. The results indicate that streamflow has undergone seven high-flow periods and four low-flow periods during the past 500 years. To identify possible transition points in the streamflow, we applied the Mann-Kendall and running T tests to the 50- and 500-year periods, respectively. During the past 500 years, streamflow has changed significantly from low to high flow about three to four times, and from high to low flow about three to five times. Over the recent 50 years, there have been three phases of variation in river runoff, and the most distinct transition of streamflow occurred in 1996.

  3. Analysis of contaminating elements in tree rings in Santiago, Chile

    Energy Technology Data Exchange (ETDEWEB)

    Romo-Kroeger, C.M.; Avila, M.J.; Eaton, L.C.; Lopez, L.A. [Faculty of Sciences. Univ. of Chile, Santiago (Chile)

    1996-12-31

    Using the 22`` isochronous cyclotron at the University of Chile, we have performed PIXE analyses on a group of samples collected from trees of metropolitan parks in Santiago. Dendrochronology was performed on each sample, which was then sectioned for the PIXE and other analyses, neutron activation and electro-chemistry. Available samples are trunk sections or cores obtained by the use of a 4.0 mm stainless steel incremental corer. We took three cores from each tree with permission of the municipalities. For the PIXE we use infinitely thick targets, as wood slabs taken along the trunk radius, and thin targets obtained by acid digestion of wood pieces and deposition on Kapton foils. Self supporting thick targets were placed directly in the PIXE chamber in a position so as to allow the irradiation of a specific annual ring. Potassium and Calcium appear as the most abundant elements in wood. Other elements such as S, Cu, Zn, As, Br and Pb were detected in amounts above the natural background in wood, and can be attributed to environmental contamination. The K/Ca ratios appear to be different for each species of tree, and seem to be related to the physico-chemical properties of wood. Preliminary results show important amounts of As and Cu (supposedly from mining origin) with increasing presence in the recent years. Pb and Zn (supposedly from vehicle origin) are also higher in recent years. (author)

  4. Spatial variability in growth-increment chronologies of long-lived freshwater mussels: Implications for climate impacts and reconstructions

    Science.gov (United States)

    Black, Bryan A.; Dunham, Jason B.; Blundon, Brett W.; Raggon, Mark F.; Zima, Daniela

    2010-01-01

    Estimates of historical variability in river ecosystems are often lacking, but long-lived freshwater mussels could provide unique opportunities to understand past conditions in these environments. We applied dendrochronology techniques to quantify historical variability in growth-increment widths in valves (shells) of western pearlshell freshwater mussels (Margaritifera falcata). A total of 3 growth-increment chronologies, spanning 19 to 26 y in length, were developed. Growth was highly synchronous among individuals within each site, and to a lesser extent, chronologies were synchronous among sites. All 3 chronologies negatively related to instrumental records of stream discharge, while correlations with measures of water temperature were consistently positive but weaker. A reconstruction of stream discharge was performed using linear regressions based on a mussel growth chronology and the regional Palmer Drought Severity Index (PDSI). Models based on mussel growth and PDSI yielded similar coefficients of prediction (R2Pred) of 0.73 and 0.77, respectively, for predicting out-ofsample observations. From an ecological perspective, we found that mussel chronologies provided a rich source of information for understanding climate impacts. Responses of mussels to changes in climate and stream ecosystems can be very site- and process-specific, underscoring the complex nature of biotic responses to climate change and the need to understand both regional and local processes in projecting climate impacts on freshwater species.

  5. Tree growth acceleration and expansion of alpine forests: The synergistic effect of atmospheric and edaphic change.

    Science.gov (United States)

    Silva, Lucas C R; Sun, Geng; Zhu-Barker, Xia; Liang, Qianlong; Wu, Ning; Horwath, William R

    2016-08-01

    Many forest ecosystems have experienced recent declines in productivity; however, in some alpine regions, tree growth and forest expansion are increasing at marked rates. Dendrochronological analyses at the upper limit of alpine forests in the Tibetan Plateau show a steady increase in tree growth since the early 1900s, which intensified during the 1930s and 1960s, and have reached unprecedented levels since 1760. This recent growth acceleration was observed in small/young and large/old trees and coincided with the establishment of trees outside the forest range, reflecting a connection between the physiological performance of dominant species and shifts in forest distribution. Measurements of stable isotopes (carbon, oxygen, and nitrogen) in tree rings indicate that tree growth has been stimulated by the synergistic effect of rising atmospheric CO2 and a warming-induced increase in water and nutrient availability from thawing permafrost. These findings illustrate the importance of considering soil-plant-atmosphere interactions to understand current and anticipate future changes in productivity and distribution of forest ecosystems.

  6. Carbon-14 activity of fallout in Araucaria angustifolia annual growth rings, from Arapoti, Parana State, Brazil; Atividade de {sup 14} C do 'fallout' em aneis anuais de crescimento de Araucaria angustifolia, de Arapoti - PR

    Energy Technology Data Exchange (ETDEWEB)

    Lisi, Claudio Sergio; Pessenda, Luiz Carlos Ruiz [Centro de Energia Nuclear na Agricultura (CENA), Piracicaba, SP (Brazil). Lab. de 14 C; Tomazello Filho, Mario [Escola Superior de Agricultura Luiz de Queiroz, Piracicaba, SP (Brazil). Dept. de Ciencias Florestais. Lab. de Dendrocronologia

    2000-07-01

    During the period of nuclear tests between 1950 and 1960, an input of artificial {sup 14} C (fallout effect) occurred in the natural reservoirs. {sup 14} C determinations in the Northern Hemisphere showed values of {delta}{sup 14} C up to 960 in the year of 1964. To determine the fallout {sup 14} C activity in Brazil, wood samples from Araucaria angustifolia (Bert.) O. Kuntze, Araucariaceae, were collected in Arapoti-PR (24 deg 11{sup S}, 49 deg 58{sup O}). The annual tree rings were selected by dendrochronology. The cellulose was extracted and its {sup 14} C activity determined by liquid scintillation method. The results showed a significant increase of the {delta} {sup 14} C up to 590 in 1965, about 60% higher than the natural activity, gradually decreasing after the end of nuclear tests. These results were correlated with those obtained in the Northen Hemisphere and will be used in the studies of CO{sub 2} mechanisms distribuition to the atmosphere and other natural reservoirs. (author)

  7. Carbon 14 dating; La datation par le carbone 14

    Energy Technology Data Exchange (ETDEWEB)

    Laj, C.; Mazaud, A.; Duplessy, J.C. [CEA Saclay, Lab. des Sciences du Climat et de l' Environnement, 91 - Gif-sur-Yvette (France)

    2004-03-01

    In this article time dating based on carbon 14 method is reviewed, its limits are explained and recent improvements are presented. Carbon 14 is a by-product of the interactions of cosmic protons with air molecules. The fluctuations of the quantity of carbon 14 present in the atmosphere are responsible for the shift observed between the result given by the method and the real age. This shift appears for ages greater than 2000 years and is estimated to 1000 years for an age of 10.000 years. As a consequence carbon 14 dating method requires calibration by comparing with other methods like dendrochronology (till 11.000 years) and time dating of fossil corals (till 26.000 years and soon till 50.000 years). It is assumed that the fluctuations of carbon 14 in the atmosphere are due to: - the changes in the intensity and composition of cosmic radiations itself (due to the motion of the sun system through the galaxy or due to the explosion of a super-novae in the surroundings of the sun system); - the changes of the earth magnetic field that diverts cosmic rays; and - the changes in the interactions between the atmosphere and the oceans knowing that 40 tons of carbon 14 are dissolved in seas while only 1 ton belongs to the atmosphere. (A.C.)

  8. Quercus macrocarpa annual, early- and latewood widths as hydroclimatic proxies, southeastern Saskatchewan, Canada

    International Nuclear Information System (INIS)

    Vanstone, Jessica R; Sauchyn, David J

    2010-01-01

    Fluctuations in size of annual ring-widths of Quercus species suggest that environmental factors influence the size and density of vessels within the ring, either by acting as a limiting factor for growth or through fine tuning of the wood structure to environmental factors. The purpose of this study is to assess the potential of Q. macrocarpa to provide multiple dendroclimatic proxies for the Canadian Prairies, by investigating growth responses of annual, early- and latewood widths to regional climate variability. Results indicate that ring width chronologies, from southeastern Saskatchewan capture regional signals related to moisture and drought conditions. Correlations suggest that late-wood widths are more representative of annual ring-widths, than are early-wood widths, and are the best proxy of seasonal fluctuations in climate. Thus regression models that include latewood widths were able to account for more variance in the Palmer Drought Severity Index (PDSI) than when annual ring-widths are used as the only proxy. This study demonstrates that Q. macrocarpa can provide multiple dendroclimatic proxies for investigating large scale climatic fluctuations at annual and sub-annual time scales. It is novel in terms of sub-annual analysis of tree-rings in a region that previously lacked dendrochronological research.

  9. How accurate is the 14C method

    International Nuclear Information System (INIS)

    Nydal, R.

    1979-01-01

    Radiocarbon daters have in recent years focussed their interest on accuracy and reliability of 14 C dates. The use of dates for resolving fine chronological structures that are not dateable otherwise has stressed this point. The total uncertainty in dating an event is composed of errors relating to dating of the sample, i.e. uncertainty in measured quantities, deviations from assumed content of 14 C in material when alive; and errors related to quality of sample material, i.e. contamination from carbon of different age, diffuse context between sample and event. Statistical variability in counting of 14 C activity gives the most important contribution to measurement uncertainty - increasing with age and shortage of sample material. Corrections for isotopic fractionation and reservoir effects must be performed, and - most important when dates are compared with historical ages - the dendrochronological calibration will correct for past variations in the atmospheric 14 C content. Future improvement of dating precision can however only be obtained by the combined efforts of both daters and submitters of samples, thus minimizing errors related to selection and handling of sample material as well as those related to the 14 C method and measurements. (Auth.)

  10. Cosmogonic radiocarbon in the Earth atmosphere

    International Nuclear Information System (INIS)

    Dergachev, V.A.

    1981-01-01

    The state and prospects of studying some processes in nature (cosmic ray intensity variations on a long time scale, mainly) using radiocarbon methods are discussed. The problem of radiocarbon preparation in exchange geochemical tanks is considered. It is noted that a set of dendrochronological and nuclear methods for analyzing tree rings is a powerful instrument for studying different processes in nature. The measurement results of radiocarbon concentration in dated wood samples for the last approximately 8000 years are presented. The relation between different indices of solar activity and the rate of radiocarbon production for separate solar cycles is investigated. The production rate variation both for separate cycles and long periods is estimated. The results of investigations lead to the conclusion that 11-year, secular, more durable peculiarities in the run of radiocarbon activity variations in the atmospheric reservoir can be explained by solar origin. The analysis of the experimental data on radiocarbon permit to compare the radiocarbon concentration variations with magnetic or solar activity [ru

  11. Modelling growth-competition relationships in trembling aspen and white spruce mixed boreal forests of Western Canada.

    Directory of Open Access Journals (Sweden)

    Jian-Guo Huang

    Full Text Available We examined the effect of competition on stem growth of Picea glauca and Populus tremuloides in boreal mixedwood stands during the stem exclusion stage. We combined traditional approaches of collecting competition data with dendrochronology to provide retrospective measurements of stem diameter growth. Several competition indices including stand basal area (BA, the sum of stem diameter at breast height (SDBH, and density (N for the broadleaf and coniferous species, as well as similar indices considering only trees with diameters greater than each subject (BAGR, SDBHGR, and NGR, were evaluated. We used a nonlinear mixed model to characterize the basal area increment over the past 5, 10, 15, 20, 25, 30, and 35 years as a function of growth of nearby dominant trees, the size of the subject trees, deciduous and coniferous competition indices, and ecoregions. SDBHGR and BAGR were better predictors for spruce, and SDBHGR and NGR were better for aspen, respectively, than other indices. Results showed strongest correlations with long-term stem growth, as the best models integrated growth for 10-25 years for aspen and ≥ 25 for spruce. Our model demonstrated a remarkable capability (adjusted R(2>0.67 to represent this complex variation in growth as a function of site, size and competition.

  12. Paleo Data Assimilation of Pseudo-Tree-Ring-Width Chronologies in a Climate Model

    Science.gov (United States)

    Fallah Hassanabadi, B.; Acevedo, W.; Reich, S.; Cubasch, U.

    2016-12-01

    Using the Time-Averaged Ensemble Kalman Filter (EnKF) and a forward model, we assimilate the pseudo Tree-Ring-Width (TRW) chronologies into an Atmospheric Global Circulation model. This study investigates several aspects of Paleo-Data Assimilation (PDA) within a perfect-model set-up: (i) we test the performance of several forward operators in the framework of a PDA-based climate reconstruction, (ii) compare the PDA-based simulations' skill against the free ensemble runs and (iii) inverstigate the skill of the "online" (with cycling) DA and the "off-line" (no-cycling) DA. In our experiments, the "online" (with cycling) PDA approach did not outperform the "off-line" (no-cycling) one, despite its considerable additional implementation complexity. On the other hand, it was observed that the error reduction achieved by assimilating a particular pseudo-TRW chronology is modulated by the strength of the yearly internal variability of the model at the chronology site. This result might help the dendrochronology community to optimize their sampling efforts.

  13. The Response of Tree-Ring Growth to Climate at Upper Timberline of Southern Aspect of Mt. Taibai

    Directory of Open Access Journals (Sweden)

    Qin Jin

    2016-01-01

    Full Text Available In recent years, the impact of climate change on vegetation in Qinling mountainous area has already been authenticated by numerous investigations, nevertheless, as the major ridge of Qinling Mountains as well as national natural conservation reserve, the ecology response of Mt. Taibai sub-alpine vegetation to climate change has not yet gained enough public attention.In this study, in accordance with the method of dendrochronology, response analysis was carried out to contrast characteristic parameters of tree-ring width chronologies for Larix chinensis from different elevations as well as their response pattern to climate change. The result showed that, Mean sensitivity, standard deviation and variance in first eigenvector are increasing with the rise of elevation, but the correlation coefficients (R1, R2, R3 were decreasing which indicated that the strength of the tree’s common or relative response to environment was decreasing with altitude. Precipitation had stronger correlation with the tree-ring radial growth than air temperature in both of the sites, during the growing season, trees in lower altitude had better correlation with temperature than in higher altitude, thus showing the different response to climate between the two different sites.

  14. Determination of self shielding factors and gamma attenuation effects for tree ring samples

    International Nuclear Information System (INIS)

    Dagistan Sahin; Kenan Uenlue

    2012-01-01

    Determination of tree ring chemistry using Neutron Activation Analysis (NAA) is part of an ongoing research between Penn State University (PSU) and Cornell University, The Malcolm and Carolyn Wiener Laboratory for Aegean and Near Eastern Dendrochronology. Tree-ring chemistry yields valuable data for environmental event signatures. These signatures are a complex function of elemental concentration. To be certain about concentration of signature elements, it is necessary to perform the measurements and corrections with the lowest error and maximum accuracy possible. Accurate and precise values of energy dependent neutron flux at dry irradiation tubes and detector efficiency for tree ring sample are calculated for Penn State Breazeale Reactor (PSBR). For the calculation of energy dependent and self shielding corrected neutron flux, detailed model of the TRIGA Mark III reactor at PSU with updated fuel compositions was prepared using the MCNP utility for reactor evolution (MURE) libraries. Dry irradiation tube, sample holder and sample were also included in the model. The thermal flux self-shielding correction factors due to the sample holder and sample for were calculated and verified with previously published values. The Geant-4 model of the gamma spectroscopy system, developed at Radiation Science and Engineering Center (RSEC), was improved and absolute detector efficiency for tree-ring samples was calculated. (author)

  15. Process models and model-data fusion in dendroecology

    Directory of Open Access Journals (Sweden)

    Joel eGuiot

    2014-08-01

    Full Text Available Dendrochronology (i.e. the study of annually dated tree-ring time series has proved to be a powerful technique to understand tree-growth. This paper intends to show the interest of using ecophysiological modeling not only to understand and predict tree-growth (dendroecology but also to reconstruct past climates (dendroclimatology. Process models have been used for several decades in dendroclimatology, but it is only recently that methods of model-data fusion have led to significant progress in modeling tree-growth as a function of climate and in reconstructing past climates. These model-data fusion (MDF methods, mainly based on the Bayesian paradigm, have been shown to be powerful for both model calibration and model inversion. After a rapid survey of tree-growth modeling, we illustrate MDF with examples based on series of Southern France Aleppo pines and Central France oaks. These examples show that if plants experienced CO2 fertilization, this would have a significant effect on tree-growth which in turn would bias the climate reconstructions. This bias could be extended to other environmental non-climatic factors directly or indirectly affecting annual ring formation and not taken into account in classical empirical models, which supports the use of more complex process-based models. Finally, we conclude by showing the interest of the data assimilation methods applied in climatology to produce climate re-analyses.

  16. Activity of Maly Aktru Glacier (Сentral Altai and changes tree line fluctuations in its basin for a historical period

    Directory of Open Access Journals (Sweden)

    A. N. Nazarov

    2016-01-01

    Full Text Available Major problems of dating of the glaciers activity from the wood residues found in moraines are discussed by the example of Maly Aktru Glacier. First of all, these are the underestimation of the glacier development features, the age of the sample itself and its content as well as losses of some outer rings. The study proves that disagreements between dendrochronological and radiocarbon ages of the samples are caused by manifestation of the Suess effect and contents of the wood cells. The reconstruction of June–July temperatures in the Aktru valley for two thousand years was used to reconstruct the altitudinal variability of the tree line thermal potential. Existence of a climatic optimum (I–IV A.D. had been revealed that brought to the higher position of the tree line in mid ages than its thermal potential could enable. On the basis of variability of growth indices for Siberian larch, it is shown that the medieval optimum stands out against a background of solely strong temperature depressions separating it from ancient and modern times, and the climate’s natural history is evidence that the current climate warming is an ordinary phenomenon.

  17. The use of Leptodyctium riparium (Hedw.) Warnst in the estimation of minimum postmortem interval.

    Science.gov (United States)

    Lancia, Massimo; Conforti, Federica; Aleffi, Michele; Caccianiga, Marco; Bacci, Mauro; Rossi, Riccardo

    2013-01-01

    The estimation of the postmortem interval (PMI) is still one of the most challenging issues in forensic investigations, especially in cases in which advanced transformative phenomena have taken place. The dating of skeletal remains is even more difficult and sometimes only a rough determination of the PMI is possible. Recent studies suggest that plant analysis can provide a reliable estimation for skeletal remains dating, when traditional techniques are not applicable. Forensic Botany is a relatively recent discipline that includes many subdisciplines such as Palynology, Anatomy, Dendrochronology, Limnology, Systematic, Ecology, and Molecular Biology. In a recent study, Cardoso et al. (Int J Legal Med 2010;124:451) used botanical evidence for the first time to establish the PMI of human skeletal remains found in a forested area of northern Portugal from the growth rate of mosses and shrub roots. The present paper deals with a case in which the study of the growth rate of the bryophyte Leptodyctium riparium (Hedw.) Warnst, was used in estimating the PMI of some human skeletal remains that were found in a wooded area near Perugia, in Central Italy. © 2012 American Academy of Forensic Sciences.

  18. Trace metal fluxes to ferromanganese nodules from the western Baltic Sea as a record for long-term environmental changes

    Energy Technology Data Exchange (ETDEWEB)

    Hlawatsch, S.; Garbe-Schonberg, C.D.; Lechtenberg, F.; Manceau, A.; Tamura, N.; Kulik, D.A.; Suess, E.; Kersten, M.

    2002-03-12

    Trace element profiles in ferromanganese nodules from the western Baltic Sea were analyzed with laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) and synchrotron-based micro-X-ray radiation techniques (fluorescence: mSXRF, and diffraction: mXRD) at high spatial resolution in growth direction. Of the trace elements studied (Zn, Cu, Cd, Ni, Co, Mo, Ba), Zn showed the most significant enrichment, with values in the outermost surface layers of up to six-fold higher than those found in older core parts. The high-resolution Zn profiles provide the necessary temporal resolution for a dating method analogous to dendrochronology. Profiles in various samples collected during two decades were matched and the overlapping sections used for estimation of the accretion rates. Assuming a continuous accretion of these relatively fast growing nodules (on average 20 mm a-1) over the last century, the Zn enrichment was thus assessed to have commenced around 1860/70 in nodules from the Kiel Bight and in 1880/90 from Mecklenburg Bight, reflecting the enhanced heavy metal emissions with rising industrialization in Europe. Apart from the obvious success with Zn, only As and Co show significant but only 1.5-fold enrichments in the most recent growth layers of the nodules. Other anthropogenic trace metals like Cu and Cd are not at all enriched, which, together with the distinct early-diagenetic Fe/Mn banding, weakens the potential of the nodules for retrospective monitoring.

  19. Solar flares and radiocarbon abundance in the atmosphere of the Earth

    International Nuclear Information System (INIS)

    Metskhvarishvili, R.Ya.; Imedadze, T.Sh.; Tleugaliev, S.Kh.; Tsinamdzgvrishvili, T.Sh.; Tsereteli, S.L.

    1978-01-01

    The correlation between the radiocarbon ( 14 C) content in the atmosphere of the Earth and the solar activity is studied. Annual measurements of the 14 C content in the tree rings for the last 120 years have been made. Relations of the radiocarbon content in dendrochronologically dated tree rings and the Wolf numbers for the period from 1850 to 1940 are presented. The spectroscopic and Borg methods have been used to ascertain the periodicities in the radiocarbon series. It is shown that well-defined periods of approximately 11 and approximately 65 years are observed in the radiocarbon series. The former is associated with an 11-year and the latter with a secular cycle of the 14 C content in the earth atmosphere. To study the relation of the solar activity to the level of radiocarbon in the earth atmosphere a mutual correlation function was calculated for various values of the time lags of 14 C with respect to the processes on the Sun. It follows from the data obtained that a positive correlation takes place for time lags smaller than three years. The detected positive correlation has revealed that the effect of solar flares in the 11-year cycle is prevalent

  20. Using Tree-Rings and Remote Sensing to Investigate Forest Productivity Response to Landscape Fragmentation in Northeastern Algeria

    Science.gov (United States)

    Rouini, N.; Lepley, K. S.; Messaoudene, M.

    2017-12-01

    Remote sensing and dendrochronology are valuable tools in the face of climate change and land use change, yet the connection between these resources remains largely unexploited. Research on forest fragmentation is mainly focused on animal groups, while our work focuses on tree communities. We link tree-rings and remotely-sensed Normalized Difference Vegetation Index (NDVI) using seasonal correlation analysis to investigate forest primary productivity response to fragmentation. Tree core samples from Quercus afares have been taken from two sites within the Guerrouche Forest in northeastern Algeria. The first site is located within a very fragmented area while the second site is intact. Fragmentation is estimated to have occurred with the construction of a road in 1930. We find raw tree-ring width chronologies from each site reveal growth release in the disturbed site after 1930. The means of each chronology for the 1930 to 2016 period are statistically different (p < 0.01). Based on these preliminary results we hypothesize that reconstructed primary productivity (NDVI) will be higher in the fragmented site after fragmentation took place.

  1. Climate Reconstruction on the Growth of Teak in Umphang Wildlife Sanctuary, Thailand

    Directory of Open Access Journals (Sweden)

    Pichit Lumyai

    2017-11-01

    Full Text Available Teak is an example of proxy data that can be used to indirectly deduce past climatic conditions. The objective of this study was to investigate the relationship between teak growth and climate data in western Thailand. Dendrochronological techniques were used to analyze 52 sample cores from Umphang Wildlife Sanctuary. The crossdated ring width data could be extended back 127 years (1886-2012. The relationship between ring-width index and climatic data indicated a positive correlation (p<0.01 with the current year total rainfall in March and June. Thus, only March and June data were used to reconstruct the annual ring width index which indicated a downward trend in the reconstructed rainfall. Considering the March and June average total rainfall, a wet period occurred in 1887-1895 and this gradually decreased to a stable pattern in 1927-1945 with a further decline to another stable level in 1957-1964. Similarly, the dry periods occurring in 1896-1926, 1946-1955, 1965-1981 and 1982-2012 could explain the high fluctuations in rainfall. Periods of 2.2-2.7 and 25.2 years were found to be common with the variations in the El Niño-Southern Oscillation. In conclusion, teak growth information can be used to monitor global warming events.

  2. Dendroclimatology in Fennoscandia – from past accomplishments to future potential

    Directory of Open Access Journals (Sweden)

    H. W. Linderholm

    2010-02-01

    Full Text Available Fennoscandia has a strong tradition in dendrochronology, and its large tracts of boreal forest make the region well suited for the development of tree-ring chronologies that extend back several thousands of years. Two of the world's longest continuous (most tree-ring chronologies are annually resolved tree-ring width chronologies are found in northern Fennoscandia, with records from Torneträsk and Finnish Lapland covering the last ca. 7500 yr. In addition, several chronologies between coastal Norway and the interior of Finland extend back several centuries. Tree-ring data from Fennoscandia have provided important information on regional climate variability during the mid to late Holocene and have played major roles in the reconstruction of hemispheric and global temperatures. Tree-ring data from the region have also been used to reconstruct large-scale atmospheric circulation patterns, regional precipitation and drought. Such information is imperative when trying to reach better understanding of natural climate change and variability and its forcing mechanisms, and placing recent climate change within a long-term context.

  3. [Tree-ring growth responses of Mongolian oak (Quercus mongolica) to climate change in southern northeast: a case study in Qianshan Mountains].

    Science.gov (United States)

    Teng, Li; Xing-Yuan, He; Zhen-Ju, Chen

    2014-07-01

    Mongolian oak is one of the most important broad-leaved tree species in forests, Northeast China. Based on the methodology of dendrochronology, the variations of tree ring radial growth of Mongolian oak in Qianshan Mountains, south of Northeast China, were analyzed. Combined with the temperature and precipitation data from meteorological stations since 1951, the relationships between standardized tree ring width chronology and main climatic factors were analyzed. In this region, the precipitation between April and July of the current year had an significant relationship with the tree ring width of Mongolian oak, and was the main factor limiting the radial growth. The extreme maximum temperature of May was also a key factor influencing the tree ring width, which had a significant on the tree ring width of Mongolian oak. The precipitation in April had a significant and stable relationship with the growth of Mongolian oak since the 1950s. The 'divergence problem' was found in the study area, which the sensitivity of tree growth to summer temperature reduced since the 1980s. The tree growth response to temperature showed a seasonal change from summer to spring.

  4. Pinus mugo Krummholz Dynamics During Concomitant Change in Pastoralism and Climate in the Central Apennines

    Directory of Open Access Journals (Sweden)

    Li Dai

    2017-02-01

    Full Text Available The dynamics of Pinus mugo krummholz during concomitant change in pastoral land use and climate in central Italy since the mid-20th century was investigated. Krummholz dynamics were detected using sequential aerial photography and fitted to a logistic regression model with elevation, grazing, proximity to beech forest, and proximity to krummholz as explanatory variables. Dendrochronological series were correlated with temperature and precipitation and fitted to a linear model. During this period krummholz doubled in extent and migrated 35–65 m upslope. Expansion was positively associated with krummholz proximity, residual pastoral grazing, and proximity to beech forest beyond 10 m and negatively associated with elevation and beech forest closer than 10 m. The logistic regression model forecasts krummholz migration by an additional 30 m upslope by 2060. During the 20th century, winter and spring minimum temperatures increased but did not result in increased radial stem growth of P. mugo. The combined evidence suggests that krummholz dynamics can be explained by the legacy of summer pastoralism and the dispersal limitations of P. mugo, rather than by climate change.

  5. Connecting with tephras : principles, functioning, and applications of tephrochronology in Quaternary science

    International Nuclear Information System (INIS)

    Lowe, D.J.

    2013-01-01

    Tephrochronology is a unique method for linking and dating geological, palaeoecological, palaeoclimatic or archaeological sequences or events. The method relies firstly and fundamentally on stratigraphy and the law of superposition, which apply in any study that connects or correlates deposits from one place to another. Secondly, it relies on characterising and hence identifying or 'fingerprinting' tephra layers using either physical properties evident in the field or those obtained from laboratory analysis, including mineralogical examination by optical microscopy or geochemical analysis of glass shards or crystals (e.g. Fe-Ti oxides, ferromagnesian minerals) using the electron microprobe and other tools. Thirdly, the method is enhanced when a numerical age is obtained for a tephra layer by (1) radiometric methods such as radiocarbon, fission-track, U-series, or Ar/Ar dating, (2) incremental dating methods including dendrochronology or varved sediments or layering in ice cores, or (3) age-equivalent methods such as palaeomagnetism or correlation with marine oxygen isotope stages or palynostratigraphy. Once known, that age can be transferred from one site to the next using stratigraphic methods and by matching compositional characteristics, i.e. comparing 'fingerprints' from each layer. Used this way, tephrochronology is an age-equivalent dating method. (author). 150 refs., 13 figs., 5 tabs.

  6. Visualizing Individual Tree Differences in Tree-Ring Studies

    Directory of Open Access Journals (Sweden)

    Mario Trouillier

    2018-04-01

    Full Text Available Averaging tree-ring measurements from multiple individuals is one of the most common procedures in dendrochronology. It serves to filter out noise from individual differences between trees, such as competition, height, and micro-site effects, which ideally results in a site chronology sensitive to regional scale factors such as climate. However, the climate sensitivity of individual trees can be modulated by factors like competition, height, and nitrogen deposition, calling attention to whether average chronologies adequately assess climatic growth-control. In this study, we demonstrate four simple but effective methods to visually assess differences between individual trees. Using individual tree climate-correlations we: (1 employed jitter plots with superimposed metadata to assess potential causes for these differences; (2 plotted the frequency distributions of climate correlations over time as heat maps; (3 mapped the spatial distribution of climate sensitivity over time to assess spatio-temporal dynamics; and (4 used t-distributed Stochastic Neighborhood Embedding (t-SNE to assess which trees were generally more similar in terms of their tree-ring pattern and their correlation with climate variables. This suite of exploratory methods can indicate if individuals in tree-ring datasets respond differently to climate variability, and therefore, should not solely be explored with climate correlations of the mean population chronology.

  7. Deep Soil Conditions Make Mediterranean Cork Oak Stem Growth Vulnerable to Autumnal Rainfall Decline in Tunisia

    Directory of Open Access Journals (Sweden)

    Lobna Zribi

    2016-10-01

    Full Text Available Tree rings provide fruitful information on climate features driving annual forest growth through statistical correlations between annual tree growth and climate features. Indices built upon tree growth limitation by carbon sequestration (source hypothesis or drought-driven cambial phenology (sink hypothesis can be used to better identify underlying processes. We used both analytical frameworks on Quercus suber, a sparsely studied species due to tree ring methodological issues, and growing on a favorable sub-humid Mediterranean climate and deep soil conditions in Tunisia (North Africa. Statistical analysis revealed the major role of autumnal rainfall before the growing season on annual tree growth over the 1918–2008 time series. Using a water budget model, we were able to explain the critical role of the deep soil water refill during the wet season in affecting both the drought onset controlling growth phenology and the summer drought intensity affecting carbon assimilation. Analysis of recent climate changes in the region additionally illustrated an increase in temperatures enhancing the evaporative demand and advancing growth start, and a decline in rainfalls in autumn, two key variables driving stem growth. We concluded on the benefits of using process-based indices in dendrochronological analysis and identified the main vulnerability of this Mediterranean forest to autumnal rainfall decline, a peculiar aspect of climate change under summer-dry climates.

  8. Connecting with tephras: principles, functioning, and applications of tephrochronology in Quaternary science

    International Nuclear Information System (INIS)

    Lowe, D.J.

    2014-01-01

    Tephrochronology is a unique method for linking and dating geological, palaeoecological, palaeoclimatic or archaeological sequences or events. The method relies firstly and fundamentally on stratigraphy and the law of superposition, which apply in any study that connects or correlates deposits from one place to another. Secondly, it relies on characterising and hence identifying or 'fingerprinting' tephra layers using either physical properties evident in the field or those obtained from laboratory analysis, including mineralogical examination by optical microscopy or geochemical analysis of glass shards or crystals (e.g. Fe-Ti oxides, ferromagnesian minerals) using the electron microprobe and other tools. Thirdly, the method is enhanced when a numerical age is obtained for a tephra layer by (1) radiometric methods such as radiocarbon, fission-track, U-series, or Ar/Ar dating, (2) incremental dating methods including dendrochronology or varved sediments or layering in ice cores, or (3) age-equivalent methods such as palaeomagnetism or correlation with marine oxygen isotope stages or palynostratigraphy. Once known, that age can be transferred from one site to the next using stratigraphic methods and by matching compositional characteristics, i.e. comparing 'fingerprints' from each layer. Used this way, tephrochronology is an age-equivalent dating method. (author)

  9. Debris Flow Occurrence and Sediment Persistence, Upper Colorado River Valley, CO.

    Science.gov (United States)

    Grimsley, K J; Rathburn, S L; Friedman, J M; Mangano, J F

    2016-07-01

    Debris flow magnitudes and frequencies are compared across the Upper Colorado River valley to assess influences on debris flow occurrence and to evaluate valley geometry effects on sediment persistence. Dendrochronology, field mapping, and aerial photographic analysis are used to evaluate whether a 19th century earthen, water-conveyance ditch has altered the regime of debris flow occurrence in the Colorado River headwaters. Identifying any shifts in disturbance processes or changes in magnitudes and frequencies of occurrence is fundamental to establishing the historical range of variability (HRV) at the site. We found no substantial difference in frequency of debris flows cataloged at eleven sites of deposition between the east (8) and west (11) sides of the Colorado River valley over the last century, but four of the five largest debris flows originated on the west side of the valley in association with the earthen ditch, while the fifth is on a steep hillslope of hydrothermally altered rock on the east side. These results suggest that the ditch has altered the regime of debris flow activity in the Colorado River headwaters as compared to HRV by increasing the frequency of debris flows large enough to reach the Colorado River valley. Valley confinement is a dominant control on response to debris flows, influencing volumes of aggradation and persistence of debris flow deposits. Large, frequent debris flows, exceeding HRV, create persistent effects due to valley geometry and geomorphic setting conducive to sediment storage that are easily delineated by valley confinement ratios which are useful to land managers.

  10. Climate effects on cork growth in Cork oak plantations in Sicily (Italy

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available Cork oak (Quercus suber L. is usually dominant in silvopastoral systems in many areas of Sicily, where the trees are debarked periodically for cork production. In spite of the importance of cork and cork oak stands in Sicilian forests and the potential economic scenarios, few research works have been carried out on these systems. Given the importance of cork thickness in cork quality evaluation, the main objective of this work is to study cork growth in cork oak productive stands spread on the north (Nebrodi Mountains and south-east (Iblei Mountains of Sicily. Image analysis techniques were used on cork surfaces of transverse sections of planks to measure cork rings. Dendrochronological analysis was applied to study annual fluctuation on rings growth in relation to various climate parameters in a cork cycle production. Results showed that rainfall, summer drought and temperature are determining factors in controlling cork growth. In siliceous areas of Nebrodi Mountains correlation between cork growth index and rainfall indicates that the rain period from May to September strongly influences phellogen activity. Temperature and water stress indices, on the other hand, show a negative correlation with cork growth. In clay and evolved soils of volcanic plateau of Iblei Mountains January precipitation shows a positive correlation with cork growth index. Also absolute minimum temperature in June and absolute maximum temperature in September show a positive correlation when temperature possibly has influence on phellogen activity during growing season.

  11. About local calibration curve of the Black Sea during the period 18000 - 3000 calendar years BP

    International Nuclear Information System (INIS)

    Slavova, K.

    2002-01-01

    Understanding the youngest geological Black Sea history requires that the age of the tested samples be accurately determined. The comparison between 234 U/ 230 Th and 14 C ages obtained on the Holocene samples demonstrate that 234 U/ 230 Th ages are accurate because they are in agreement with the dendrochonological calibration. Beyond 9100 calendar year BP it is proved that 14 C ages are systematically younger than 234 U/ 230 Th ages with a maximum difference of about 3000 years reached at about 20000 calendar years. This calls for converting the conventional 14 C ages in calendar ages. The procedure is called calibration. A local calibration Black Sea curve in which features of the Black Sea as a basin to be included is required, videlicet: correction of conventional ages for 'reservoir effect' - 60 years for TOC (Total Organic Carbon), 460 years for TCC (Total Carbonate Carbon) and for 'detrital carbon input - 580 years for TOC, 260 years for TCC. Such local calibration curve is constructed and proved in the article by using and comparing data from different dating methods (carbon 14, 234 U/ 230 Th, dendrochronology)

  12. The frequency of forest fires in Scots pine stands of Tuva, Russia

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova, G A; Kukavskaya, E A [Russian Academy of Sciences, Siberian Branch, V N Sukachev Institute of Forest, Akademgorodok, Krasnoyarsk, 660036 (Russian Federation); Ivanov, V A [Siberian State Technological University, Krasnoyarsk, 660049 (Russian Federation); Soja, A J, E-mail: GAIvanova@ksc.krasn.r [National Institute of Aerospace, Resident at NASA Langley Research Center, MS 420, Hampton, VA 23681-2199 (United States)

    2010-01-15

    Forest fires resulting from long periods of drought cause extensive forest ecosystem destruction and can impact on the carbon balance and air quality and feed back to the climate system, regionally and globally. Past fire frequency is reconstructed for Tuvan Scots pine stands using dendrochronology and statistics. Central Tuvan Scots pine (Pinus sylvestris) stands are subject to annual fire regimes; however high intensity fires are rare but they are responsible for most of the damage. Low, medium, and high severity fires have shaped the multi-story Scots pine communities, locally and regionally. Fire type and frequency are directly related to weather and climate and are also dependent on anthropogenic influences. The primary dry period, which promotes fire ignition and spread, in Tuva occurs in April and May. In some years, the precipitation deficit combined with high air temperatures induces long periods of drought. Unlike the typical surface fire regime, forest fires that burn during these extreme droughts often become crown fires that result in substantial forest damage and carbon release. The mean fire interval (MFI) is found to be 10.4 years in Balgazyn stands, and the landscape-scale MFI is 22.4 years. High severity, stand-replacing crown fires have a longer MFI. The warmer and dryer weather that is predicted by global climate models is evident in Tuva, and we believe that these changes in weather and climate have resulted in increased fire intensity and severity, rather than fire frequency in the Tuvan region.

  13. Investigation of a connection of variations of atmospheric radiocarbon activity with some geophysical and astrophysical phenomena

    International Nuclear Information System (INIS)

    Kocharov, G.E.; Chernov, S.B.

    1980-01-01

    Relation of the radiocarbon concentration is dendrochronologically dated wood samples to solar activity, geomagnetic field variations and changes of global temperature near the earth surface for the last 500 years is studied. It is found that averaged 10-year Δ 14 C fluctuations of radiocarbon content in annual rings of trees experience noticeable variations with the 0.5% amplitude. To reveal the effect in the best way the Δ 14 C values averaged in the intervals equal to 11-year solar activity cycles and with a 4-year shift in relation to the latter, are obtained. It is shown that in the 1700-1805 period of time the Δ 14 C averaged values corresponding to peak values of the even 11-year solar activity cycles are mainly lower than the Δ 14 C averaged values corresponding to the odd cycle maximum values. In the 1835-1900 period the 14 C averaged values corresponding to the odd solar cycle maximum values are lesser than the Δ 14 C averaged values corresponding to the even cycle peaks [ru

  14. Relating annual increments of the endangered Blanding's turtle plastron growth to climate.

    Science.gov (United States)

    Richard, Monik G; Laroque, Colin P; Herman, Thomas B

    2014-05-01

    This research is the first published study to report a relationship between climate variables and plastron growth increments of turtles, in this case the endangered Nova Scotia Blanding's turtle (Emydoidea blandingii). We used techniques and software common to the discipline of dendrochronology to successfully cross-date our growth increment data series, to detrend and average our series of 80 immature Blanding's turtles into one common chronology, and to seek correlations between the chronology and environmental temperature and precipitation variables. Our cross-dated chronology had a series intercorrelation of 0.441 (above 99% confidence interval), an average mean sensitivity of 0.293, and an average unfiltered autocorrelation of 0.377. Our master chronology represented increments from 1975 to 2007 (33 years), with index values ranging from a low of 0.688 in 2006 to a high of 1.303 in 1977. Univariate climate response function analysis on mean monthly air temperature and precipitation values revealed a positive correlation with the previous year's May temperature and current year's August temperature; a negative correlation with the previous year's October temperature; and no significant correlation with precipitation. These techniques for determining growth increment response to environmental variables should be applicable to other turtle species and merit further exploration.

  15. Measurement of {sup 14}C time scale of the rings of a tree by accelerator mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Oda, Hirotaka; Furukawa, Michiaki [Nagoya Univ. (Japan). School of Science; Yonenobu, Hitoshi; Ikeda, Akiko; Nakamura, Toshio

    1996-12-01

    {sup 14}C time scale is different from a histrical data in order that it is calculated by assuming that the concentration of {sup 14}C in the sample has not been changed by age. The object of this work is to make clear the errors in measurement of {sup 14}C time scale of the ring of a tree known the tree age. The every year ring of a Hinoki in Kiso, 950 years old, was used as a sample. The most external ring is determined as 1923 years old on the basis of the dendrochronology. The rings after 1120 years were used as the samples. {alpha}-cellulose, the most stable component in the structural components of cell of tree, was prepared from each ring. About 8 mg of {alpha}-cellulose was reduced to graphite to be measured by the tandem thoron analytic meter. The results obtained showed that {sup 14}C time scale was older than that of the histrical data in the twelfth and thirteenth century, but it was more new than that of the histrical data from the late seventeenth to the middle of eighteenth century. The results were agreement with that of Stuiver and Pearson (1933). (S.Y.)

  16. Reviewing the Mid-First Millennium BC {sup 14}C 'warp' using {sup 14}C/bristlecone pine data

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, R.E., E-mail: retaylor@ucr.edu [Department of Anthropology, University of California, Riverside, Riverside, CA (United States); Cotsen Institute of Archaeology, University of California, Los Angeles, CA (United States); Keck Carbon Cycle Accelerator Mass Spectrometry Laboratory, University of California, Irvine, CA (United States); Southon, John [Keck Carbon Cycle Accelerator Mass Spectrometry Laboratory, University of California, Irvine, CA (United States)

    2013-01-15

    AMS-based {sup 14}C measurements have been obtained on 53 dendrochronologically-dated Bristlecone pine (Pinus longaeva) wood samples in decadal increments spanning 2300-2750 cal BP with particular interest focused on the decades centered on 2405 cal BP and 2625 cal BP. In general, there is overall agreement with the current IntCal04/09 consensus calibration curve for this period. For the 2400-2410 cal BP interval, our Bristlecone-based {sup 14}C value is consistent with the {sup 14}C value obtained by Belfast on Irish oak for that decade but not on German oak values obtained by Seattle. Our {sup 14}C value for the 2620-2630 cal BP interval is consistent with the German oak (Heidelberg)-based {sup 14}C decadal value. The {sup 10}Be-based reconstruction of {sup 14}C variations over the 2620-2630 cal BP interval also supports the Heidelberg data although clearly additional clarifications are required before the current tree ring-based {sup 14}C and ice core-based {sup 10}Be data for this interval can be accurately interpreted and valid inferences obtained.

  17. Multi-proxy reconstructions and the power of integration across marine, terrestrial, and freshwater ecosystems. (Invited)

    Science.gov (United States)

    Black, B.

    2013-12-01

    Over the past decade, dendrochronology (tree-ring analysis) techniques have been increasingly applied to growth increments of various bivalve, fish, and coral species. In particular, the use of crossdating ensures that all increments in a dataset have assigned the correct calendar year of formation and that the resulting chronology is exactly placed in time. Such temporal alignment facilitates direct comparisons among chronologies that span diverse taxa and ecosystems, illustrating the pervasive, synchronizing influence of climate from alpine forests to the continental slope. Such an approach can be particularly beneficial to reconstructions in that each species captures climate signals from its unique 'perspective' of life history and habitat. For example, combinations of tree-ring data and chronologies for the long-lived bivalve Pacific geoduck (Panopea generosa) capture substantially more variance in regional sea surface temperatures than either proxy could explain alone. Just as importantly, networks of chronologies spanning multiple trophic levels can help identify climate variables critical to ecosystem functioning, which can then be targeted to generate most biologically relevant reconstructions possible. Along the west coast of North America, fish and bivalve chronologies in combination with records of seabird reproductive success indicate that winter sea-level pressure is closely associated with California Current productivity, which can be hind-cast over the past six centuries using coastal tree-ring chronologies. Thus, multiple proxies not only increase reconstruction skill, but also help isolate climate variables most closely linked to ecosystem structure and functioning.

  18. Application of the axial tomography computed for the detection of bags of dampness in dry wood of Gmelina arborea (Roxb.)

    International Nuclear Information System (INIS)

    Moya R, Roger; Munoz A, Freddy; Escalante, Ivan

    2006-01-01

    Gmelina arborea (Roxb.) is widely used for commercial reforestation in Costa Rica due to its excellent growth rate and productivity. However, during the lumber drying process, the wooden boards show non-uniform values of final moisture content (MC). The low uniformity in final MC is caused by the presence of wet pockets, originated during the growing process of the tree. The regions with wet pockets present zones with a high MC, which are hard to detect with traditional methods for MC measurements during the wood drying process. It is possible to detect and to set the limits of the presence of wet wood in Gmelina arborea boards using scanning computed tomography (CT-scanning), a technique applied in medical diagnostic. A board with wet pockets is shown in the CT-scanning images in clear color and with low values of the Hounsfield Unit (HU) or CT number. When these values were transformed to wood density, it was determined that wet pockets were in a density of around 190 kg/m 3 , a value higher than normal wood. Also, it was possible to observe growth tree rings in the CT-scanning images, an important feature for dendrochronological research. The obtained results allowed showing that it is possible to apply this technique in the process of lumber production, to detect the zones with high MC in kiln dried Gmelina arborea wood. (author) [es

  19. Utilizing Urban Environments for Effective Field Experiences

    Science.gov (United States)

    MacAvoy, S. E.; Knee, K.

    2014-12-01

    Research surveys suggest that students are demanding more applied field experiences from their undergraduate environmental science programs. For geoscience educators at liberal arts colleges without field camps, university vehicles, or even geology departments, getting students into the field is especially rewarding - and especially challenging. Here, we present strategies that we have used in courses ranging from introductory environmental science for non-majors, to upper level environmental methods and geology classes. Urban locations provide an opportunity for a different type of local "field-work" than would otherwise be available. In the upper-level undergraduate Environmental Methods class, we relied on a National Park area located a 10-minute walk from campus for most field exercises. Activities included soil analysis, measuring stream flow and water quality parameters, dendrochronology, and aquatic microbe metabolism. In the non-majors class, we make use of our urban location to contrast water quality in parks and highly channelized urban streams. Here we share detailed lesson plans and budgets for field activities that can be completed during a class period of 2.5 hours with a $75 course fee, show how these activities help students gain quantitative competency, and provide student feedback about the classes and activities.

  20. Urban Field Experiences for Undergraduate Liberal Arts Students: Using Compromised Environments as Living Laboratories

    Science.gov (United States)

    MacAvoy, S. E.; Knee, K.

    2015-12-01

    While urban environments may lack the beauty of relatively pristine field sites, they can be used to deliver an effective demonstration of actual environmental damage. Students demanding applied field experiences from their undergraduate environmental science programs can be well served in urban settings. Here, we present strategies for integrating degraded urban systems into the undergraduate field experience. Urban locations provide an opportunity for a different type of local "field-work" than would otherwise be available. In the upper-level undergraduate Environmental Methods class, we relied on a National Park area located a 10-minute walk from campus for most field exercises. Activities included soil analysis, measuring stream flow and water quality parameters, dendrochronology, and aquatic microbe metabolism. In the non-majors class, we make use of our urban location to contrast water quality in parks and highly channelized urban streams. Students spend labs immersed in streams and wetlands heavily impacted by the urban runoff their city generates. Here we share lesson plans and budgets for field activities that can be completed during a class period of 2.5 hours with a $75 course fee, show how these activities help students gain quantitative competency.

  1. Increasing Drought Sensitivity and Decline of Atlas Cedar (Cedrus atlantica in the Moroccan Middle Atlas Forests

    Directory of Open Access Journals (Sweden)

    Jesús Julio Camarero

    2011-09-01

    Full Text Available An understanding of the interactions between climate change and forest structure on tree growth are needed for decision making in forest conservation and management. In this paper, we investigated the relative contribution of tree features and stand structure on Atlas cedar (Cedrus atlantica radial growth in forests that have experienced heavy grazing and logging in the past. Dendrochronological methods were applied to quantify patterns in basal-area increment and drought sensitivity of Atlas cedar in the Middle Atlas, northern Morocco. We estimated the tree-to-tree competition intensity and quantified the structure in Atlas cedar stands with contrasting tree density, age, and decline symptoms. The relative contribution of tree age and size and stand structure to Atlas cedar growth decline was estimated by variance partitioning using partial-redundancy analyses. Recurrent drought events and temperature increases have been identified from local climate records since the 1970s. We detected consistent growth declines and increased drought sensitivity in Atlas cedar across all sites since the early 1980s. Specifically, we determined that previous growth rates and tree age were the strongest tree features, while Quercus rotundifolia basal area was the strongest stand structure measure related to Atlas cedar decline. As a result, we suggest that Atlas cedar forests that have experienced severe drought in combination with grazing and logging may be in the process of shifting dominance toward more drought-tolerant species such as Q. rotundifolia.

  2. Many missing rings in old Canary pines can be related with age, fires and traditional uses

    Energy Technology Data Exchange (ETDEWEB)

    Génova, M.; Santana, C.; Martínez, B.

    2017-11-01

    Aim and area of study: In the present paper we estimated the age of four monumental Pinus canariensis of Gran Canaria (Canary Islands, Spain) by means of tree-ring analysis. Many tree-ring series have been accurately studied and many missing rings have been determined. Material and methods: The trees were dead and the samples analysed were big disks. We measured numerous radii and crossdated the individual tree-ring series, paying particular attention to the existence and location of missing rings. We have distinguished between missing outer rings (MORs) and missing inner rings (MIRs) and analysed the possible causes of both. Main results: We determined an average of 8.8% total missing rings (MRs) for these long-lived trees, with a maximum of 96 MRs in a series of over 500. We have tried to establish a tree-ring chronology on Gran Canaria Island, also having the tree-ring series from Inagua site, but the long individual tree-ring series analysed do not crossdate between them. Research highlights: We consider the Canary pine a species hard to conducting dendroecological studies, especially if the samples come from managed old trees, in which a large amount of known and potentially unknown missing rings can hampered dating. Even knowing the difficulties involved in dendrochronological analyses of P. canariensis, we can confirm that it is a long-lived species, which can grow to over 500 years, and some of whose growth changes could be associated with certain historical and ecological events.

  3. Spatial dynamics of Fabiana imbricata shrublands in northwestern Patagonia in relation to natural fires

    Directory of Open Access Journals (Sweden)

    L. Ghermandi

    2010-05-01

    Full Text Available Fire is a critical disturbance in the structuring and functioning of most Mediterranean ecosystems. In northwestern Patagonia, vegetation patterns are strongly influenced by fire and environmental heterogeneity. Dendroecology, together with satellite imagery and GIS, have been demonstrated to be useful tools in studies that relate to fire effects with patches, patterns and species dynamics at landscape scale. Such studies can be approached from landscape ecology, which has evolved in the last years supported by the development of remote sensing and GIS technologies. This study evaluates the spatial dynamic of F. imbricata in response to fire using remote sensing, GIS and dendrochronology techniques, at landscape scale. Two sites were evaluated and one of them was affected by fire in the year 1999. The digital processing images (using the NBR spectral index and the dendroecological analysis verified this. A fire, occurring in 1978, was also detected by the analysis of F. imbricata growth rings. The relation between F. imbricata shrubland dynamics and spatial configuration with fire, land topography and hydrography was established in the study area.

  4. Growth-climate relationships across topographic gradients in the northern Great Lakes

    Science.gov (United States)

    Dymond, S.F.; D'Amato, A.W.; Kolka, R.K.; Bolstad, P.V.; Sebestyen, S.D.; Bradford, John B.

    2016-01-01

    Climatic conditions exert important control over the growth, productivity, and distribution of forests, and characterizing these relationships is essential for understanding how forest ecosystems will respond to climate change. We used dendrochronological methods to develop climate–growth relationships for two dominant species, Populus tremuloides (quaking aspen) and Pinus resinosa (red pine), in the upper Great Lakes region to understand how climate and water availability influence annual forest productivity. Trees were sampled along a topographic gradient at the Marcell Experimental Forest (Minnesota, USA) to assess growth response to variations in temperature and different water availability metrics (precipitation, potential evapotranspiration (PET), cumulative moisture index (CMI), and soil water storage). Climatic variables were able to explain 33–58% of the variation in annual growth (as measured by ring-width increment) for quaking aspen and 37–74% of the variation for red pine. Climate–growth relationships were influenced by topography for quaking aspen but not for red pine. Annual ring growth for quaking aspen decreased with June CMI on ridges, decreased with temperature in the November prior to the growing season on sideslopes, and decreased with June PET on toeslopes. Red pine growth increased with increasing July PET across all topographic positions. These results indicate the sensitivity of both quaking aspen and red pine to local climate and show several vulnerabilities of these species to shifts in water supply and temperature because of climate change.

  5. Effects of thinning on drought vulnerability and climate response in north temperate forest ecosystems

    Science.gov (United States)

    D’Amato, Anthony W.; Bradford, John B.; Fraver, Shawn; Palik, Brian J.

    2013-01-01

    Reducing tree densities through silvicultural thinning has been widely advocated as a strategy for enhancing resistance and resilience to drought, yet few empirical evaluations of this approach exist. We examined detailed dendrochronological data from a long-term (>50 yrs) replicated thinning experiment to determine if density reductions conferred greater resistance and/or resilience to droughts, assessed by the magnitude of stand-level growth reductions. Our results suggest that thinning generally enhanced drought resistance and resilience; however, this relationship showed a pronounced reversal over time in stands maintained at lower tree densities. Specifically, lower-density stands exhibited greater resistance and resilience at younger ages (49 years), yet exhibited lower resistance and resilience at older ages (76 years), relative to higher-density stands. We attribute this reversal to significantly greater tree sizes attained within the lower-density stands through stand development, which in turn increased tree-level water demand during the later droughts. Results from response-function analyses indicate that thinning altered growth-climate relationships, such that higher-density stands were more sensitive to growing-season precipitation relative to lower-density stands. These results confirm the potential of density management to moderate drought impacts on growth, and they highlight the importance of accounting for stand structure when predicting climate-change impacts to forest systems.

  6. The frequency of forest fires in Scots pine stands of Tuva, Russia

    International Nuclear Information System (INIS)

    Ivanova, G A; Kukavskaya, E A; Ivanov, V A; Soja, A J

    2010-01-01

    Forest fires resulting from long periods of drought cause extensive forest ecosystem destruction and can impact on the carbon balance and air quality and feed back to the climate system, regionally and globally. Past fire frequency is reconstructed for Tuvan Scots pine stands using dendrochronology and statistics. Central Tuvan Scots pine (Pinus sylvestris) stands are subject to annual fire regimes; however high intensity fires are rare but they are responsible for most of the damage. Low, medium, and high severity fires have shaped the multi-story Scots pine communities, locally and regionally. Fire type and frequency are directly related to weather and climate and are also dependent on anthropogenic influences. The primary dry period, which promotes fire ignition and spread, in Tuva occurs in April and May. In some years, the precipitation deficit combined with high air temperatures induces long periods of drought. Unlike the typical surface fire regime, forest fires that burn during these extreme droughts often become crown fires that result in substantial forest damage and carbon release. The mean fire interval (MFI) is found to be 10.4 years in Balgazyn stands, and the landscape-scale MFI is 22.4 years. High severity, stand-replacing crown fires have a longer MFI. The warmer and dryer weather that is predicted by global climate models is evident in Tuva, and we believe that these changes in weather and climate have resulted in increased fire intensity and severity, rather than fire frequency in the Tuvan region.

  7. Relevance of medieval, Egyptian and American dates to the study of climatic and radiocarbon variability

    International Nuclear Information System (INIS)

    Berger, R.

    1990-01-01

    Basic radiocarbon dating and dendrochronology have been combined to yield calibrated dates that are more accurate than conventional radiocarbon dates. This has been shown to be true for medieval and Egyptian dynastic dating. Because radiocarbon is a cosmogenically produced radioisotope, heliomagnetic and geomagnetic fields play a major role in its synthesis in the Earth's upper atmosphere. Inasmuch as a calibrated radiocarbon record exists for nearly 10 000 years, we now seem to possess in the short-time variations of the production rate a history of solar activity expressed via heliomagnetic fields carried by the solar wind. In turn, solar activity has a controlling effect on climate on Earth within modifications provided by the complex interactions of the atmosphere-Earth-ocean system. Both radiocarbon measurements and other empirical research methods agree on variations of climate during historically more recent periods on Earth. This leads to the suggestion that the radiocarbon calibration curve may be also a significant indicator or tracer for climatic changes for the Holocene or the Neolithic-Mesolithic. (author)

  8. KAJIAN ANATOMI KAYU PADA TIGA EKOTIPE Pinus merkusii SUMATERA DAN POTENSINYA SEBAGAI INDIKATOR PERUBAHAN IKLIM

    Directory of Open Access Journals (Sweden)

    Yulia Sandri

    2016-09-01

    Full Text Available Recently, climate change is the one of most important environmental issue. Climate variability can be recorded by tree growing through the growth ring. Growth ring formed by cambial activity were examined in wood anatomy. In Sumatra, there are three ecotypes Pinus merkusii, namely ecotypes Kerinci, Tapanuli, and Aceh which can be distinguished morphologically. This study aims to knowing the wood anatomical characteristics of the three ecotypes and determine the potential as climate indicator. This study was conducted in October 2014 until June 2015. Sample of Kerinci ecotype was collected in Kerinci Seblat National Park, Tapanuli ecotype in Dolok Sibualbuali Natural Reserve and Aceh ecotype in Gunung Leuser National Park on a height of 130 cm using increment borer and cut on the main stem 5×5 cm for anatomical sample. Results from this study indicate that ecotype Kerinci and Tapanuli showed earlywood and latewood boundary exposing the clear growth ring, whereas in Aceh ecotype unclear. Tapanuli ecotype have the thickest tracheid diameter than ecotype Kerinci and Aceh. Ecotypes of Kerinci, Tapanuli, and Aceh has homoceluler and uniseriate ray where Aceh ecotype have the longest ray. Furthermore, Kerinci and Tapanuli ecotype have potential as climate indicator eventhough showed negative correlation, that Tapanuli ecotype show the best result and recommended in dendrochronology study.

  9. Climate-Induced Larch Growth Response Within the Central Siberian Permafrost Zone

    Science.gov (United States)

    Kharuk, Viacheslav I.; Ranson, Kenneth J.; Im, Sergei T.; Petrov, Il'ya A.

    2015-01-01

    Aim: estimation of larch (Larix gmelinii) growth response to current climate changes. Location: permafrost area within the northern part of Central Siberia (approximately 65.8 deg N, 98.5 deg E). Method: analysis of dendrochronological data, climate variables, drought index SPEI, GPP (gross primary production) and EVI vegetation index (both Aqua/MODIS satellite derived), and soil water content anomalies (GRACE satellite measurements of equivalent water thickness anomalies, EWTA). Results: larch tree ring width (TRW) correlated with previous year August precipitation (r = 0.63), snow accumulation (r = 0.61), soil water anomalies (r = 0.79), early summer temperatures and water vapor pressure (r = 0.73 and r = 0.69, respectively), May and June drought index (r = 0.68-0.82). There are significant positive trends of TRW since late 1980s and GPP since the year 2000. Mean TRW increased by about 50%, which is similar to post-Little Ice Age warming. TRW correlated with GPP and EVI of larch stands (r = 0.68-0.69). Main conclusions: within the permafrost zone of central Siberia larch TRW growth is limited by early summer temperatures, available water from snowmelt, water accumulated within soil in the previous year, and permafrost thaw water. Water stress is one of the limiting factors of larch growth. Larch TRW growth and GPP increased during recent decades.

  10. Relevance of medieval, Egyptian and American dates to the study of climatic and radiocarbon variability

    Energy Technology Data Exchange (ETDEWEB)

    Berger, R [California Univ., Los Angeles, CA (USA). Inst. of Geophysics and Planetary Physics

    1990-04-24

    Basic radiocarbon dating and dendrochronology have been combined to yield calibrated dates that are more accurate than conventional radiocarbon dates. This has been shown to be true for medieval and Egyptian dynastic dating. Because radiocarbon is a cosmogenically produced radioisotope, heliomagnetic and geomagnetic fields play a major role in its synthesis in the Earth's upper atmosphere. Inasmuch as a calibrated radiocarbon record exists for nearly 10 000 years, we now seem to possess in the short-time variations of the production rate a history of solar activity expressed via heliomagnetic fields carried by the solar wind. In turn, solar activity has a controlling effect on climate on Earth within modifications provided by the complex interactions of the atmosphere-Earth-ocean system. Both radiocarbon measurements and other empirical research methods agree on variations of climate during historically more recent periods on Earth. This leads to the suggestion that the radiocarbon calibration curve may be also a significant indicator or tracer for climatic changes for the Holocene or the Neolithic-Mesolithic. (author).

  11. Estimating floodplain sedimentation in the Laguna de Santa Rosa, Sonoma County, CA

    Science.gov (United States)

    Curtis, Jennifer A.; Flint, Lorraine E.; Hupp, Cliff R.

    2013-01-01

    We present a conceptual and analytical framework for predicting the spatial distribution of floodplain sedimentation for the Laguna de Santa Rosa, Sonoma County, CA. We assess the role of the floodplain as a sink for fine-grained sediment and investigate concerns regarding the potential loss of flood storage capacity due to historic sedimentation. We characterized the spatial distribution of sedimentation during a post-flood survey and developed a spatially distributed sediment deposition potential map that highlights zones of floodplain sedimentation. The sediment deposition potential map, built using raster files that describe the spatial distribution of relevant hydrologic and landscape variables, was calibrated using 2 years of measured overbank sedimentation data and verified using longer-term rates determined using dendrochronology. The calibrated floodplain deposition potential relation was used to estimate an average annual floodplain sedimentation rate (3.6 mm/year) for the ~11 km2 floodplain. This study documents the development of a conceptual model of overbank sedimentation, describes a methodology to estimate the potential for various parts of a floodplain complex to accumulate sediment over time, and provides estimates of short and long-term overbank sedimentation rates that can be used for ecosystem management and prioritization of restoration activities.

  12. Parliamentary role and relationship in effectively addressing climate change issues - Swaziland

    Energy Technology Data Exchange (ETDEWEB)

    Brown, R

    2011-01-15

    Climate change is defined as any long-term and significant change in the expected patterns of a specific region's average weather for an appropriately significant period of time. It is the result of several factors, including Earth?s dynamic processes, external forces, and more recently, human activity. External factors that shape climate include such processes as variations in solar radiation, deviations in Earth's orbit, and variations in the level of greenhouse gas concentrations. Evidence of climatic change taken from a variety of sources can, in turn, be used to reconstruct past climates. Most climate evidence is inferred from changes in key climate indicators, including vegetation, ice cores, dendrochronology, sea-level change, and glacial geology. Climate change represents one of the greatest environmental, social, and economic threats facing the planet today. In developing countries, Swaziland included, climate change will likely have a significant impact on the livelihoods and living conditions of the poor. It is a particular threat to the attainment of the Millennium Development Goals (MDGs) and progress in sustainable development in Sub-Saharan Africa. Increasing temperatures and shifting rain patterns across Africa reduce access to food and create effects that impact regions, farming systems, households, and individuals in varying ways. Additional global changes, including changed trade patterns and energy policies, have the potential to exacerbate the negative effects of climate change on some of these systems and groups.

  13. Assessing Ecotourism Potential of Traditional Wooden Architecture in Rural Areas: The Case of Papart Valley

    Directory of Open Access Journals (Sweden)

    Taner Okan

    2016-09-01

    Full Text Available The aim of this study is to reveal the resource values that the rural areas host, and with a very disciplined approach, to discuss opportunities to benefit from those values in terms of ecotourism practices specific to Papart Valley. As a first step in this study, we took an inventory of natural and cultural assets of Papart Valley in Eastern Black Sea Region, Artvin province. Then, a Strengths, Weaknesses, Opportunities and Threats (SWOT analysis was conducted with the participation of all stakeholders and the current situation was analyzed in terms of ecotourism practices. In light of SWOT results, along with observed natural resource assets in the region, the traditional wooden houses were seen to have potential in terms of ecotourism and it was detected that there were a large number of wooden homes and home plans suitable for both the settlement of the local people and accommodation of guests. On the other hand, it was determined that there was a lack of information for sufficient protection and care of wooden houses, and despite their potential, there was a lack of regulations and positive attitudes towards accomodation businesses in traditional wooden houses. In order to eliminate these deficiencies, proposals for the protection of traditional building stock were developed, by first determining the causes of material degradation in the wooden houses. Also, to emphasize the worth and importance of these structures, dendrochronology studies were conducted in order to determine the antiquity of the structures and potentially to make them more attractive for eco-tourism.

  14. [Dendroclimatic potentials for the tree rings of Huangshan pine (Pinus taiwanensis ) at Xiaolinhai in the western Dabie Mountains, China].

    Science.gov (United States)

    Peng, Jian-Feng; Li, Guo-Dong; Li, Ling-Ling

    2014-07-01

    By using the dendrochronology research methods, this paper developed the 1915-2011 tree ring-width standard chronology of the Huangshan pine (Pinus taiwanesis) at the north slope of western Dabie Mountains in the junction of Hubei, Henan and Anhui provinces. High mean sensitivity (MS) indicated that there was conspicuous high-frequency climate signals and high first-order autocorrelation (AC) showed there were significant lag-effects of tree previous growth. The higher signal-to-noise ratio (SNR) and expressed population signal (EPS) indicated that the trees had high levels of common climate signals. Correlations between the tree ring-width standard chronology and climatic factors (1959-2011) revealed the significant influences of temperature, precipitation and relative humidity on the tree width growth of Huangshan pine by the end of growing season (September and October). Significant positive correlations were found between the tree-ring indices and the Palmer drought severity index (PDSI) of current September and October. In conclusion, the combination of water and heat of September and October is the major effect factor for the growth of Huangshan pine in western Dabie Mountains.

  15. Effects of Drought on Xylem Anatomy and Water-Use Efficiency of Two Co-Occurring Pine Species

    Directory of Open Access Journals (Sweden)

    Dario Martin-Benito

    2017-09-01

    Full Text Available Exploring how drought influences growth, performance, and survival in different species is crucial to understanding the impacts of climate change on forest ecosystems. Here, we investigate the responses of two co-occurring pines (Pinus nigra and Pinus sylvestris to interannual drought in east-central Spain by dendrochronological and wood anatomical features integrated with isotopic ratios of carbon (δ13C and oxygen (δ18O in tree rings. Our results showed that drought induces both species to allocate less carbon to build tracheid cell-walls but increases tracheid lumen diameters, particularly in the transition wood between early and latewood, potentially maximizing hydraulic conductivity but reducing resistance to embolism at a critical phase during the growing season. The thicker cell-wall-to-lumen ratio in P. nigra could imply that its xylem may be more resistant to bending stress and drought-induced cavitation than P. sylvestris. In contrast, the higher intrinsic water-use efficiency (iWUE in P. sylvestris suggests that it relies more on a water-saving strategy. Our results suggest that narrower cell-walls and reduced growth under drought are not necessarily linked to increased iWUE. At our site P. nigra showed a higher growth plasticity, grew faster and was more competitive than P. sylvestris. In the long term, these sustained differences in iWUE and anatomical characters could affect forest species performance and composition, particularly under increased drought stress.

  16. Drought Influence over Radial Growth of Mexican Conifers Inhabiting Mesic and Xeric Sites

    Directory of Open Access Journals (Sweden)

    Marín Pompa-García

    2017-05-01

    Full Text Available Drought is a major constraint of forest productivity and tree growth across diverse habitat types. In this study, we investigated the drought responses of four conifer species growing within two locations of differing elevation and climatic conditions in northern Mexico. Two species were selected at a mesic site (Cupressus lusitanica Mill., Abies durangensis Martínez and the other two species were sampled at a xeric site (Pinus engelmannii Carr., Pinus cembroides Zucc.. Using a dendrochronological approach, we correlated the radial-growth series of each species and the climatic variables. All study species positively responded to wet-cool conditions during winter and spring. Despite the close proximity of species at a mesic site, A. durangensis had high responsiveness to hydroclimatic variability, but C. lusitanica was not responsive. At the xeric site, P. engelmannii and P. cembroides were very responsive to drought severity, differentiated only by the longer time scale of the response to accumulated drought of P. engelmannii. The responsiveness to hydroclimate and drought of these tree species seems to be modulated by site conditions, or by the functional features of each species that are still little explored. These findings indicate that differentiating between mesic and xeric habitats is a too coarse approach in diverse forests with a high topographic heterogeneity.

  17. Reconstruction of March-June precipitation from tree rings in central Liaoning, China

    Science.gov (United States)

    Wang, Yanchao; Liu, Yu

    2017-11-01

    A dendrochronological profile was generated from Chinese pines ( Pinus tabulaeformis Carr.) in the Qianshan Mountains in northeastern China. Based on correlation analyses, the pattern of precipitation from March to June ( P 36 ) was reconstructed using a simple linear model, which explained 42.7% of the total variance in observed precipitation from 1951 to 2012. The reconstructed P 36 series revealed a consistently increasing trend in precipitation during the twentieth century in the Qianshan Mountains. The reconstructed data showed trends that were similar to those in the variation in trends for March-June precipitation observed at the Shenyang station, the reconstructed January-May precipitation trends in Shenyang City, and the reconstructed average June-September relative humidity for Yiwulü Mountain. The reconstructed data also showed good agreement with the droughts reported in historical documents and recorded by meteorological stations in Liaoning. Spatial correlation analyses show that the reconstructed data reflect the variability in precipitation that occurs over much of northeastern China. In addition, our reconstruction showed a significant periodicity. The significant correlations between the reconstructed P 36 and the El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and sunspot numbers indicate that precipitation variability in the Qianshan Mountain region is probably driven by extensive atmosphere-sea interactions and solar activities.

  18. Changes in tree resistance, recovery and resilience across three successive extreme droughts in the northeast Iberian Peninsula.

    Science.gov (United States)

    Serra-Maluquer, X; Mencuccini, M; Martínez-Vilalta, J

    2018-05-01

    Understanding which variables affect forest resilience to extreme drought is key to predict future dynamics under ongoing climate change. In this study, we analyzed how tree resistance, recovery and resilience to drought have changed along three consecutive droughts and how they were affected by species, tree size, plot basal area (as a proxy for competition) and climate. We focused on the three most abundant pine species in the northeast Iberian Peninsula: Pinus halepensis, P. nigra and P. sylvestris during the three most extreme droughts recorded in the period 1951-2010 (occurred in 1986, 1994, and 2005-2006). We cored trees from permanent sample plots and used dendrochronological techniques to estimate resistance (ability to maintain growth level during drought), recovery (growth increase after drought) and resilience (capacity to recover pre-drought growth levels) in terms of tree stem basal area increment. Mixed-effects models were used to determine which tree- and plot-level variables were the main determinants of resistance, recovery and resilience, and to test for differences among the studied droughts. Larger trees were significantly less resistant and resilient. Plot basal area effects were only observed for resilience, with a negative impact only during the last drought. Resistance, recovery and resilience differed across the studied drought events, so that the studied populations became less resistant, less resilient and recovered worse during the last two droughts. This pattern suggests an increased vulnerability to drought after successive drought episodes.

  19. Determinants of fire activity during the last 3500 yr at a wildland-urban interface, Alberta, Canada

    Science.gov (United States)

    Davis, Emma L.; Courtney Mustaphi, Colin J.; Gall, Amber; Pisaric, Michael F. J.; Vermaire, Jesse C.; Moser, Katrina A.

    2016-11-01

    Long-term records of wildfires and their controlling factors are important sources of information for informing land management practices. Here, dendrochronology and lake sediment analyses are used to develop a 3500-yr fire and vegetation history for a montane forest in Jasper National Park, Alberta, Canada. The tree-ring record (AD 1771-2012) indicates that this region historically experienced a mixed-severity fire regime, and that effective fire suppression excluded widespread fire events from the study area during the 20th century. A sediment core collected from Little Trefoil Lake, located near the Jasper townsite, is analyzed for subfossil pollen and macroscopic charcoal (>150 μm). When comparing the tree-ring record to the 3500-yr record of sediment-derived fire events, only high-severity fires are represented in the charcoal record. Comparisons between the charcoal record and historical climate and pollen data indicate that climate and vegetation composition have been important controls on the fire regime for most of the last 3500 yr. Although fire frequency is presently within the historical range of variability, the fire return interval of the last 150 yr is longer than expected given modern climate and vegetation conditions, indicating that humans have become the main control on fire activity around Little Trefoil Lake.

  20. Drought impact on water use efficiency and intra-annual density fluctuations in Erica arborea on Elba (Italy).

    Science.gov (United States)

    Battipaglia, Giovanna; DE Micco, Veronica; Brand, Willi A; Saurer, Matthias; Aronne, Giovanna; Linke, Petra; Cherubini, Paolo

    2014-02-01

    Erica arborea (L) is a widespread Mediterranean species, able to cope with water stress and colonize semiarid environments. The eco-physiological plasticity of this species was evaluated by studying plants growing at two sites with different soil moistures on the island of Elba (Italy), through dendrochronological, wood-anatomical analyses and stable isotopes measurements. Intra-annual density fluctuations (IADFs) were abundant in tree rings, and were identified as the key parameter to understand site-specific plant responses to water stress. Our findings showed that the formation of IADFs is mainly related to the high temperature, precipitation patterns and probably to soil water availability, which differs at the selected study sites. The recorded increase in the (13) C-derived intrinsic water use efficiency at the IADFs level was linked to reduced water loss rather than to increasing C assimilation. The variation in vessel size and the different absolute values of δ(18) O among trees growing at the two study sites underlined possible differences in stomatal control of water loss and possible differences in sources of water uptake. This approach not only helped monitor seasonal environmental differences through tree-ring width, but also added valuable information on E. arborea responses to drought and their ecological implications for Mediterranean vegetation dynamics. © 2013 John Wiley & Sons Ltd.

  1. Dynamics at the treeline: differential responses of Picea mariana and Larix laricina to climate change in eastern subarctic Québec

    International Nuclear Information System (INIS)

    Dufour-Tremblay, Geneviève; Boudreau, Stéphane; Lévesque, Esther

    2012-01-01

    Treelines are known to be temperature-sensitive ecotones, and therefore could rapidly expand their range limits in response to climate warming. Observations of lack of range expansion, however, indicate that ecological constraints partly control the treeline ecotones. The main objectives of this study were to evaluate Picea mariana and Larix laricina recruitment and growth at and above the altitudinal treeline of Kangiqsualujjuaq (Nunavik), where warmer temperatures since the 1990s have already triggered shrub expansion. We mapped, harvested, dated and measured tree individuals along two altitudinal gradients from the forested stands below the treeline to hilltops. Since the 1990s, a pulse of L. laricina seedling establishment has occurred at and above the treeline. Dendrochronological analysis revealed that L. laricina underwent a rapid vertical growth and radial growth that accelerated from the 1990s. No recruitment was observed for P. mariana in response to the regional warming, suggesting a regeneration failure of this species. Our results indicated that the L. laricina colonization below and above the treeline in recent decades in response to the regional warming should modify the landscape physiognomy of the study area in the near future. (letter)

  2. Climate warming and the recent treeline shift in the European alps: the role of geomorphological factors in high-altitude sites.

    Science.gov (United States)

    Leonelli, Giovanni; Pelfini, Manuela; di Cella, Umberto Morra; Garavaglia, Valentina

    2011-05-01

    Global warming and the stronger regional temperature trends recently recorded over the European Alps have triggered several biological and physical dynamics in high-altitude environments. We defined the present treeline altitude in three valleys of a region in the western Italian Alps and reconstructed the past treeline position for the last three centuries in a nearly undisturbed site by means of a dendrochronological approach. We found that the treeline altitude in this region is mainly controlled by human impacts and geomorphological factors. The reconstruction of the altitudinal dynamics at the study site reveals that the treeline shifted upwards of 115 m over the period 1901-2000, reaching the altitude of 2505 m in 2000 and 2515 m in 2008. The recent treeline shift and the acceleration of tree colonization rates in the alpine belt can be mainly ascribed to the climatic input. However, we point out the increasing role of geomorphological factors in controlling the future treeline position and colonization patterns in high mountains.

  3. Winter precipitation effect in a mid-latitude temperature-limited environment: the case of common juniper at high elevation in the Alps

    International Nuclear Information System (INIS)

    Pellizzari, Elena; Pividori, Mario; Carrer, Marco

    2014-01-01

    Common juniper (Juniperus communis L.) is by far the most widespread conifer in the world. However, tree-ring research dealing with this species is still scarce, mainly due to the difficulty in crossdating associated with the irregular stem shape with strip-bark growth form in older individuals and the high number of missing and wedging rings. Given that many different species of the same genus have been successfully used in tree-ring investigations and proved to be reliable climate proxies, this study aims to (i) test the possibility to successfully apply dendrochronological techniques on common juniper growing above the treeline and (ii) verify the climate sensitivity of the species with special regard to winter precipitation, a climatic factor that generally does not affect tree-ring growth in all Alpine high-elevation tree species. Almost 90 samples have been collected in three sites in the central and eastern Alps, all between 2100 and 2400 m in elevation. Despite cross-dating difficulties, we were able to build a reliable chronology for each site, each spanning over 200 years. Climate-growth relationships computed over the last century highlight that juniper growth is mainly controlled by the amount of winter precipitation. The high variability of the climate-growth associations among sites, corresponds well to the low spatial dependence of this meteorological factor. Fairly long chronologies and the presence of a significant precipitation signal open up the possibility to reconstruct past winter precipitation. (letter)

  4. The ralationship between the Tamarix spp. growth and lake level change in the Bosten Lake,northwest China

    Science.gov (United States)

    Ye, Mao; Hou, JiaWen

    2015-04-01

    Dendrochronology methods are used to analyze the characteristics of Tamarix spp. growth in Bosten Lake. Based on the long-term annual and monthly data of lake level, this paper models the relationship between ring width of Tamarix spp. and lake level change. The sensitivity index is applied to determine the rational change range of lake level for protecting the Tamarix spp. growth. The results show that :( 1) the annual change of lake level in Bosten Lake has tree evident stages from 1955 to 2012. The monthly change of lake level has two peak values and the seasonal change is not significant; (2) the average value of radical width of Tamarix spp. is 3.39mm. With the increment of Tamarix spp. annual growth , the average radical width has a decreasing trend, which is similar to the annual change trend of lake level in the same years ;( 3) the response of the radical width of Tamarix spp. to annual change of lake level is sensitive significantly. When the lake level is 1045.66m, the Sk value of radical width of Tamarix spp. appears minimum .when the lake level is up to1046.27m, the Sk value is maximum. Thus the sensitivity level of radical width of Tamarix spp. is 1045.66- 1046.27m which could be regarded as the rational lake level change range for protecting the Tamarix spp. growth.

  5. Extreme Drought Events Revealed in Amazon Tree Ring Records

    Science.gov (United States)

    Jenkins, H. S.; Baker, P. A.; Guilderson, T. P.

    2010-12-01

    The Amazon basin is a center of deep atmospheric convection and thus acts as a major engine for global hydrologic circulation. Yet despite its significance, a full understanding of Amazon rainfall variability remains elusive due to a poor historical record of climate. Temperate tree rings have been used extensively to reconstruct climate over the last thousand years, however less attention has been given to the application of dendrochronology in tropical regions, in large part due to a lower frequency of tree species known to produce annual rings. Here we present a tree ring record of drought extremes from the Madre de Dios region of southeastern Peru over the last 190 years. We confirm that tree ring growth in species Cedrela odorata is annual and show it to be well correlated with wet season precipitation. This correlation is used to identify extreme dry (and wet) events that have occurred in the past. We focus on drought events identified in the record as drought frequency is expected to increase over the Amazon in a warming climate. The Cedrela chronology records historic Amazon droughts of the 20th century previously identified in the literature and extends the record of drought for this region to the year 1816. Our analysis shows that there has been an increase in the frequency of extreme drought (mean recurrence interval = 5-6 years) since the turn of the 20th century and both Atlantic and Pacific sea surface temperature (SST) forcing mechanisms are implicated.

  6. Radiocarbon dating of a pine tree (Pinus densiflora) from Yeongwol, Korea

    International Nuclear Information System (INIS)

    Kim, C.H.; Lee, J.H.; Kang, J.; Song, S.; Yun, M.H.; Kim, J.C.

    2015-01-01

    We report the results of the dating of a pine tree (Pinus densiflora) from Yeongwol, Korea. The age of the tree was estimated to be in the range of hundreds of years, however, the tree had been broken by a strong wind in March 2010 and now only the stump of the tree is left. At the time of sampling in 2014, there were several decayed parts in the stump, so using the usual dendrochronological method (i.e. ring counting) for dating was difficult. However, we found a small wood sample with tree rings near the center of the stump that could be used for radiocarbon wiggle-match dating. Radiocarbon dates were determined using Accelerator mass spectrometry (AMS). The IntCal13 curve was used to calibrate the radiocarbon dates, and the wiggle matching technique was used to reduce the error of the calibrated ages. Based on the dating results, we suggest that the pine tree is approximately 300 years or older.

  7. The Remarkable Metrological History of Radiocarbon Dating [II].

    Science.gov (United States)

    Currie, Lloyd A

    2004-01-01

    This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought (14)C measurement from a crude, bulk [8 g carbon] dating tool, to a refined probe for dating tiny amounts of precious artifacts, and for "molecular dating" at the 10 µg to 100 µg level. The metrological advances led to opportunities and surprises, such as the non-monotonic dendrochronological calibration curve and the "bomb effect," that gave rise to new multidisciplinary areas of application, ranging from archaeology and anthropology to cosmic ray physics to oceanography to apportionment of anthropogenic pollutants to the reconstruction of environmental history. Beyond the specific topic of natural (14)C, it is hoped that this account may serve as a metaphor for young scientists, illustrating that just when a scientific discipline may appear to be approaching maturity, unanticipated metrological advances in their own chosen fields, and unanticipated anthropogenic or natural chemical events in the environment, can spawn new areas of research having exciting theoretical and practical implications.

  8. Radiocarbon dating of a pine tree (Pinus densiflora) from Yeongwol, Korea

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C.H.; Lee, J.H.; Kang, J.; Song, S.; Yun, M.H. [AMS Lab., NCIRF, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, J.C. [Dept. of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2015-10-15

    We report the results of the dating of a pine tree (Pinus densiflora) from Yeongwol, Korea. The age of the tree was estimated to be in the range of hundreds of years, however, the tree had been broken by a strong wind in March 2010 and now only the stump of the tree is left. At the time of sampling in 2014, there were several decayed parts in the stump, so using the usual dendrochronological method (i.e. ring counting) for dating was difficult. However, we found a small wood sample with tree rings near the center of the stump that could be used for radiocarbon wiggle-match dating. Radiocarbon dates were determined using Accelerator mass spectrometry (AMS). The IntCal13 curve was used to calibrate the radiocarbon dates, and the wiggle matching technique was used to reduce the error of the calibrated ages. Based on the dating results, we suggest that the pine tree is approximately 300 years or older.

  9. Radiocarbon dating of a pine tree (Pinus densiflora) from Yeongwol, Korea

    Science.gov (United States)

    Kim, C. H.; Lee, J. H.; Kang, J.; Song, S.; Yun, M. H.; Kim, J. C.

    2015-10-01

    We report the results of the dating of a pine tree (Pinus densiflora) from Yeongwol, Korea. The age of the tree was estimated to be in the range of hundreds of years, however, the tree had been broken by a strong wind in March 2010 and now only the stump of the tree is left. At the time of sampling in 2014, there were several decayed parts in the stump, so using the usual dendrochronological method (i.e. ring counting) for dating was difficult. However, we found a small wood sample with tree rings near the center of the stump that could be used for radiocarbon wiggle-match dating. Radiocarbon dates were determined using Accelerator mass spectrometry (AMS). The IntCal13 curve was used to calibrate the radiocarbon dates, and the wiggle matching technique was used to reduce the error of the calibrated ages. Based on the dating results, we suggest that the pine tree is approximately 300 years or older.

  10. The remarkable metrological history of 14C dating: from ancient Egyptian artifacts to particles of soot and grains of pollen

    International Nuclear Information System (INIS)

    Currie, L.A.

    2003-01-01

    Radiocarbon dating would not have been possible if 14 C had not had the 'wrong' half-life - a fact that delayed its discovery. Following the discovery of this 5730 year radionuclide in laboratory experiments by Ruben and Kamen, it became clear to W. F. Libby that 14 C should exist in nature, and that it could serve as a quantitative means for dating artifacts and events marking the history of civilization. The search for natural radiocarbon was a metrological challenge; the level in the living biosphere (ca. 230 Bq/kg) lay far beyond the then current state of the measurement art. This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought 14 C measurement from a crude, bulk (8 g carbon) dating tool, to a refined probe for dating tiny amounts of precious artifacts, and for 'molecular dating' at the 10 μg to 100 mg level. The metrological advances led to opportunities and surprises, such as the non-monotonic dendrochronological calibration curve and the 'bomb effect', that spawned new multidisciplinary areas of application, ranging from cosmic ray physics to oceanography to the reconstruction of environmental history. (author)

  11. Uncover the mantle: rediscovering Gregório Lopes palette and technique with a study on the painting "Mater Misericordiae"

    Science.gov (United States)

    Antunes, Vanessa; Candeias, António; Oliveira, Maria J.; Carvalho, Maria L.; Dias, Cristina Barrocas; Manhita, Ana; Francisco, Maria J.; Costa, Sónia; Lauw, Alexandra; Manso, Marta

    2016-11-01

    Gregório Lopes (c. 1490-1550) was one of the most prominent painters of the renaissance and Mannerism in Portugal. The painting "Mater Misericordiae" made for the Sesimbra Holy House of Mercy, circa 1535-1538, is one of the most significant works of the artist, and his only painting on this theme, being also one of the most significant Portuguese paintings of sixteenth century. The recent restoration provided the possibility to study materially the painting for the first time, with a multianalytical methodology incorporating portable energy-dispersive X-ray fluorescence spectroscopy, scanning electron microscopy-energy-dispersive spectroscopy, micro-X-ray diffraction, micro-Raman spectroscopy and high-performance liquid chromatography coupled to diode array and mass spectrometry detectors. The analytical study was complemented by infrared reflectography, allowing the study of the underdrawing technique and also by dendrochronology to confirm the date of the wooden panels (1535-1538). The results of this study were compared with previous ones on the painter's workshop, and significant differences and similitudes were found in the materials and techniques used.

  12. Estimating long-term statistics for annual precipitation for six regions of the United States from tree-ring data

    International Nuclear Information System (INIS)

    Fritts, H.C.; DeWitt, E.; Gordon, G.A.; Hunt, J.H.; Lofgren, G.R.

    1979-12-01

    Spatial anomalies of seasonal precipitation for the United States and southwestern Canada have been reconstructed from 1602 through 1961 using dendrochronological and multivariate techniques on 65 arid-site tree-ring chronologies from western North America. Seasonal reconstructions are averaged to obtain mean annual precipitation values for six regions of importance to the Nuclear Regulatory Commission (NRC) Nuclear Waste Management Program (NWMP). Statistics calculated from the regionally averaged annual values for 25-year and longer intervals show annual precipitation in the seventeenth through nineteenth centuries to be lower than in the twentieth century for three regions in the American Southwest and higher for one region in the Northwest and two regions in the East. The variability of precipitation generally was higher in the past three centuries than in the present century. Twenty-five-year intervals with noteworthy statistics are identified and important results are summarized and tabulated for use in the hydrologic modeling of the NWMP. Additional research is recommended to incorporate temperature and precipitation into a single hydrologic parameter

  13. Discovery of modern (post-1850 CE) lavas in south-central British Columbia, Canada: Origin from coal fires or intraplate volcanism?

    Science.gov (United States)

    Canil, Dante; Mihalynuk, Mitch; Lacourse, Terri

    2018-01-01

    We describe three unusual lavas in the Northern Cordillera in south-central British Columbia, Canada, occurring as spatter, scoria and blocks over small 400 m2 areas. The lavas coat and weld cobbles and pebbles in glacial till and are vesicular and glassy with microlites of clinopyroxene and plagioclase, and xenocrysts of quartz, feldspar or clinopyroxene. Chemically the lavas are basaltic trachyandesite (55-61 wt% SiO2) with trace element patterns similar to average British Columbia upper crust, except for having higher V and lower Zr, Hf, Nb, Th and U. Melting experiments and plagioclase-melt thermometry on the glasses, and phase equilibrium in simple systems, require liquidus temperatures of 1150-1300 °C. Interaction of the liquids with carbonaceous matter at low pressure formed Fe metal spherules and SiC. Radiocarbon ages of charcoal and dendrochronology show the lavas are modern, emplaced in the last 120 years. The similar bulk composition of these lavas to several other Quaternary-aged volcanic centers in the North American Cordillera, some of which show recent seismic activity, could suggest a possible tectonic origin, but the deposits are unusually small and show no central vent for emplacement. Conversely, the balance of evidence would suggest an origin from coal fires or hot gas venting, but is less consistent with the observed calc- and per-alkaline lava compositions, and the lack of known local coal-bearing strata as a heat source. Other anthropogenic origins for the lavas are considered less plausible.

  14. Stable isotope investigations from tree rings (Betula pubescens) in Northern Iceland

    International Nuclear Information System (INIS)

    Bertler, N.A.N.; Rose, J.J.; Mattey, D.P.; Brownlees, M.; Stoetter, J.E.

    1999-01-01

    Stable isotope investigations from recent trees (Betual pubescens) from two different locations in Northern Iceland have been carried out to examine applicability for paleoclimatic research. The aim was to correlate oxygen and carbon isotope data of annual and three year resolution derived from individual rings with meteorological data, in order to establish a calibration function for fossil wood samples. A precise dendrochronological record has been established for all cores to permit a direct comparison between different data sets. The material used for the isotopic analysis is pure α-cellulose. The oxygen and carbon ratios were measured using a new technique, employing CO with continuous flow mass spectrometry. As this method does not allow a simultaneous measurements of the carbon ratios, the δ 13 C values have been analysed separately, using CO 2 . Both methods demonstrated their reliability through high precision and accuracy in the values for the measured standards. However there is little confidence in the sample data, as they suffer from poor precision and non-consistency

  15. Traffic pollution affects tree-ring width and isotopic composition of Pinus pinea

    Energy Technology Data Exchange (ETDEWEB)

    Battipaglia, Giovanna, E-mail: giovanna.battipaglia@wsl.ch [WSL Swiss Federal Institute for Forest, Snow and Landscape Research, CH-8903 Birmensdorf (Switzerland); Department of Environmental Sciences, Second University of Naples, Via Vivaldi 43, I-81100 Caserta (Italy); Marzaioli, Fabio; Lubritto, Carmine; Altieri, Simona; Strumia, Sandro [Department of Environmental Sciences, Second University of Naples, Via Vivaldi 43, I-81100 Caserta (Italy); Cherubini, Paolo [WSL Swiss Federal Institute for Forest, Snow and Landscape Research, CH-8903 Birmensdorf (Switzerland); Cotrufo, M. Francesca [Department of Environmental Sciences, Second University of Naples, Via Vivaldi 43, I-81100 Caserta (Italy); Department of Soil and Crop Sciences, Colorado State University, CO (United States)

    2010-01-01

    This study presents new evidence that radiocarbon, combined with dendrochronological and stable isotopes analysis in tree rings and needles, can help to better understand the influence of pollution on trees. Pinus pinea individuals, adjacent to main roads in the urban area of Caserta (South Italy) and exposed to large amounts of traffic exhaust since 1980, were sampled and the time-related trend in the growth residuals was estimated. We found a consistent decrease in the ring width starting from 1980, with a slight increase in {delta}{sup 13}C value, which was considered to be a consequence of environmental stress. No clear pattern was identified in {delta}{sup 15}N, while an increasing effect of the fossil fuel dilution on the atmospheric bomb-enriched {sup 14}C background was detected in tree rings, possibly as a consequence of the increase in traffic exhausts. Our findings suggested that radiocarbon is a very sensitive tool to investigate small-scale (i.e. traffic exhaust at the level crossing) and large-scale (urban area pollution) induced disturbances.

  16. Regional growth decline of sugar maple (Acer saccharum) and its potential causes

    Science.gov (United States)

    Bishop, Daniel A.; Beier, Colin M.; Pederson, Neil; Lawrence, Gregory B.; Stella, John C; Sullivan, Timothy J.

    2015-01-01

    Sugar maple (Acer saccharum Marsh) has experienced poor vigor, regeneration failure, and elevated mortality across much of its range, but there has been relatively little attention to its growth rates. Based on a well-replicated dendrochronological network of range-centered populations in the Adirondack Mountains (USA), which encompassed a wide gradient of soil fertility, we observed that the majority of sugar maple trees exhibited negative growth trends in the last several decades, regardless of age, diameter, or soil fertility. Such growth patterns were unexpected, given recent warming and increased moisture availability, as well as reduced acidic deposition, which should have favored growth. Mean basal area increment was greater on base-rich soils, but these stands also experienced sharp reductions in growth. Growth sensitivity of sugar maple to temperature and precipitation was non-stationary during the last century, with overall weaker relationships than expected. Given the favorable competitive status and age structure of the Adirondack sugar maple populations sampled, evidence of widespread growth reductions raises concern over this ecologically and economically important tree. Further study will be needed to establish whether growth declines of sugar maple are occurring more widely across its range.

  17. Connecting, synchronising, and dating with tephras : principles and applications of tephrochronology in Quaternary research

    International Nuclear Information System (INIS)

    Lowe, D.J.

    2017-01-01

    Tephrochronology is a unique method for linking and dating geological, palaeoecological, palaeoclimatic or archaeological sequences or events. The method relies firstly and fundamentally on stratigraphy and the law of superposition, which apply in any study that connects or correlates deposits from one place to another. Secondly, it relies on characterising and hence identifying or 'fingerprinting' tephra layers using either physical properties evident in the field or those obtained from laboratory analysis, including mineralogical examination by optical microscopy or geochemical analysis of glass shards or crystals (e.g. Fe-Ti oxides, ferromagnesian minerals) using the electron microprobe and other tools. Thirdly, the method is enhanced when a numerical age is obtained for a tephra layer by (1) radiometric methods such as radiocarbon, fission-track, U-series, or Ar/Ar dating, (2) incremental dating methods including dendrochronology or varved sediments or layering in ice cores, or (3) age-equivalent methods such as palaeomagnetism or correlation with marine oxygen isotope stages or palynostratigraphy. Once known, that age can be transferred from one site to the next using stratigraphic methods and by matching compositional characteristics, i.e. comparing 'fingerprints' from each layer. Used this way, tephrochronology is an age-equivalent dating method. (author).

  18. Competition amplifies drought stress in forests across broad climatic and compositional gradients

    Science.gov (United States)

    Gleason, Kelly; Bradford, John B.; Bottero, Alessandra; D'Amato, Tony; Fraver, Shawn; Palik, Brian J.; Battaglia, Michael; Iverson, Louis R.; Kenefic, Laura; Kern, Christel C.

    2017-01-01

    Forests around the world are experiencing increasingly severe droughts and elevated competitive intensity due to increased tree density. However, the influence of interactions between drought and competition on forest growth remains poorly understood. Using a unique dataset of stand-scale dendrochronology sampled from 6405 trees, we quantified how annual growth of entire tree populations responds to drought and competition in eight, long-term (multi-decadal), experiments with replicated levels of density (e.g., competitive intensity) arrayed across a broad climatic and compositional gradient. Forest growth (cumulative individual tree growth within a stand) declined during drought, especially during more severe drought in drier climates. Forest growth declines were exacerbated by high density at all sites but one, particularly during periods of more severe drought. Surprisingly, the influence of forest density was persistent overall, but these density impacts were greater in the humid sites than in more arid sites. Significant density impacts occurred during periods of more extreme drought, and during warmer temperatures in the semi-arid sites but during periods of cooler temperatures in the humid sites. Because competition has a consistent influence over growth response to drought, maintaining forests at lower density may enhance resilience to drought in all climates.

  19. The remarkable metrological history of 14C dating: From ancient Egyptian artifacts to particles of soot and grains of pollen

    Science.gov (United States)

    Currie, L. A.

    2003-01-01

    Radiocarbon dating would not have been possible if 14C had not had the “wrong” half-life—a fact that delayed its discovery [1]. Following the discovery of this 5730 year radionuclide in laboratory experiments by Ruben and Kamen, it became clear to W. F. Libby that 14C should exist in nature, and that it could serve as a quantitative means for dating artifacts and events marking the history of civilization. The search for natural radiocarbon was a metrological challenge; the level in the living biosphere [ca. 230 Bq/kg] lay far beyond the then current state of the measurement art. This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought 14C measurement from a crude, bulk [8 g carbon] dating tool, to a refined probe for dating tiny amounts of precious artifacts, and for “molecular dating” at the 10 μg to 100 μg level. The metrological advances led to opportunities and surprises, such as the non-monotonic dendrochronological calibration curve and the “bomb effect,” that spawned new multidisciplinary areas of application, ranging from cosmic ray physics to oceanography to the reconstruction of environmental history.

  20. Some comments on the terminology of the Late Glacial in Central Europe and the problem of its application to SW Europe

    Directory of Open Access Journals (Sweden)

    Olaf JÖRIS

    2013-05-01

    Full Text Available Today, the Late Glacial interstadials Bølling and Allerød, originally defined in northern Europe, are often applied as chronozones in different palaeoclimate contexts across the Northern Hemisphere. The scientific community in both palaeoclimate research and archaeology often disregards the fact that the Meiendorf interstadial has long been identified as preceding the Bølling-Allerød sequence, and that there are lots of difficulties with the synchronization of the Oldest Dryas-Bølling-Older Dryas-sequence. Synchronization of important Central European high-resolution pollen records with the Greenland GRIP ice core demonstrates a strong climatic gradient from the South to the North of Europe over the entire Late Glacial. Therefore, the northern European interstadials (Meiendorf, Bølling, Allerød cannot serve universally as Late Glacial chronozones with reference to their characteristic pollen compositions, even though they are of greatest importance for the understanding of the regional vegetational history. The Greenland ice cores offer continous climate information over the entire Late Glacial and may serve as chronostratigraphical type sections. In the close future, detailed synchronization of terrestrial sequences with the Greenland ice core records will be achieved, using high-precision radiocarbon calibration based on Late Glacial dendrochronologies.

  1. Growth Response of Northern White-Cedar (Thuja occidentalis to Natural Disturbances and Partial Cuts in Mixedwood Stands of Quebec, Canada

    Directory of Open Access Journals (Sweden)

    Jean-Claude Ruel

    2014-05-01

    Full Text Available Northern white-cedar (Thuja occidentalis is a species of high commercial and ecological value, the abundance of which has been declining since the middle of the 19th century. Very little information regarding its silviculture in mixedwood stands is currently available, even though a significant portion of wood resources comes from these stands. The present study is a retrospective analysis of white-cedar growth in partially harvested mixedwood stands of western Quebec, Canada. Eight stands distributed across two regions were analyzed. Dendrochronological approaches examined long-term diameter growth for sample white-cedar trees and stems of associated species. These approaches were used to reconstruct stand characteristics at the time of harvesting, together with local harvesting intensity. The study demonstrated white-cedar’s capacity to maintain good growth for long periods of time and at large tree sizes. Accession to the upper canopy positions occurs through repeated episodes of suppression/release, most of which seem to be associated with spruce budworm (Choristoneura fumiferana outbreaks. White-cedar response to partial harvesting varies with tree size, residual basal area and species composition. Growth response was generally stronger for small trees, even though large trees still maintained the best diameter growth. Growth of white-cedar was negatively affected by an increase in softwood proportion in basal area. Growth responses to harvesting could be sustained for a period of 20 years.

  2. Increase of radiocarbon concentration in tree rings from Kujawy (SE Poland) around AD 774-775

    Science.gov (United States)

    Rakowski, Andrzej Z.; Krąpiec, Marek; Huels, Mathias; Pawlyta, Jacek; Dreves, Alexander; Meadows, John

    2015-10-01

    Evidence of a rapid increase in atmospheric radiocarbon (14C) content in AD 774-775 was presented by Miyake et al. (2012), who observed an increase of about 12‰ in the 14C content in annual tree rings from Japanese cedar. Usoskin et al. (2013) report a similar 14C spike in German oak, and attribute it to exceptional solar activity. If this phenomenon is global in character, such rapid changes in 14C concentration may affect the accuracy of calibrated dates, as the existing calibration curve is composed mainly of decadal samples. Single-year samples of dendro-chronologically dated tree rings of deciduous oak (Quercus robur) from Kujawy, a village near Krakow (SE Poland), spanning the years AD 765-796, were collected and their 14C content was measured using the AMS system in the Leibniz Laboratory. The results clearly show a rapid increase of 9.2 ± 2.1‰ in the 14C concentration in tree rings between AD 774 and AD 775, with maximum Δ14C = 4.1 ± 2.3‰ noted in AD 776.

  3. Increase of radiocarbon concentration in tree rings from Kujawy (SE Poland) around AD 774–775

    International Nuclear Information System (INIS)

    Rakowski, Andrzej Z.; Krąpiec, Marek; Huels, Mathias; Pawlyta, Jacek; Dreves, Alexander; Meadows, John

    2015-01-01

    Evidence of a rapid increase in atmospheric radiocarbon ( 14 C) content in AD 774–775 was presented by Miyake et al. (2012), who observed an increase of about 12‰ in the 14 C content in annual tree rings from Japanese cedar. Usoskin et al. (2013) report a similar 14 C spike in German oak, and attribute it to exceptional solar activity. If this phenomenon is global in character, such rapid changes in 14 C concentration may affect the accuracy of calibrated dates, as the existing calibration curve is composed mainly of decadal samples. Single-year samples of dendro-chronologically dated tree rings of deciduous oak (Quercus robur) from Kujawy, a village near Krakow (SE Poland), spanning the years AD 765–796, were collected and their 14 C content was measured using the AMS system in the Leibniz Laboratory. The results clearly show a rapid increase of 9.2 ± 2.1‰ in the 14 C concentration in tree rings between AD 774 and AD 775, with maximum Δ 14 C = 4.1 ± 2.3‰ noted in AD 776.

  4. Increase of radiocarbon concentration in tree rings from Kujawy (SE Poland) around AD 774–775

    Energy Technology Data Exchange (ETDEWEB)

    Rakowski, Andrzej Z., E-mail: arakowski@polsl.pl [Leibniz-Laboratory for Radiometric Dating and Isotope Research, University Kiel, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Institute of Physics – Center for Science and Education, Silesian University of Technology, Konarskiego Str. 22B, 44-100 Gliwice (Poland); Krąpiec, Marek [AGH University of Science and Technology, Mickiewicza Av. 30, 30-059 Krakow (Poland); Huels, Mathias [Leibniz-Laboratory for Radiometric Dating and Isotope Research, University Kiel, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Pawlyta, Jacek [Institute of Physics – Center for Science and Education, Silesian University of Technology, Konarskiego Str. 22B, 44-100 Gliwice (Poland); Dreves, Alexander [Leibniz-Laboratory for Radiometric Dating and Isotope Research, University Kiel, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Meadows, John [Leibniz-Laboratory for Radiometric Dating and Isotope Research, University Kiel, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Centre for Baltic and Scandinavian Archaeology, Schleswig-Holstein State Museums Foundation, Schloss Gottorf, Schloßinsel, 24837 Schleswig (Germany)

    2015-10-15

    Evidence of a rapid increase in atmospheric radiocarbon ({sup 14}C) content in AD 774–775 was presented by Miyake et al. (2012), who observed an increase of about 12‰ in the {sup 14}C content in annual tree rings from Japanese cedar. Usoskin et al. (2013) report a similar {sup 14}C spike in German oak, and attribute it to exceptional solar activity. If this phenomenon is global in character, such rapid changes in {sup 14}C concentration may affect the accuracy of calibrated dates, as the existing calibration curve is composed mainly of decadal samples. Single-year samples of dendro-chronologically dated tree rings of deciduous oak (Quercus robur) from Kujawy, a village near Krakow (SE Poland), spanning the years AD 765–796, were collected and their {sup 14}C content was measured using the AMS system in the Leibniz Laboratory. The results clearly show a rapid increase of 9.2 ± 2.1‰ in the {sup 14}C concentration in tree rings between AD 774 and AD 775, with maximum Δ{sup 14}C = 4.1 ± 2.3‰ noted in AD 776.

  5. Models of sustainable use of alder (Alnus acuminate Kunth hillside area in forest mist

    Directory of Open Access Journals (Sweden)

    Pacheco-Agudo Edilberto

    2016-05-01

    Full Text Available Timber extractions non planned affect negatively in the reduction of forest cover, proper management and planned with minor extractions preserve the natural production allow for longer and sustainable forms a stand to benefit local populations and the same ecosystem. In the basin of Acero Marca has two stands Alnus acuminata that they are extracted continuously. With the purpose of planning the extraction of timber resourses were constructed and evaluated matrix models sustainable harvest of this species on the basis of structures of age. For this, two old structures we worked following a dendrochronological analysis and demographic model of the forestall mass, from making local information by transectos Gentry. According to the demographic model, the potential regression evidences significant differences (p 1 and could be the most appropriate for a planned extraction becoming sustainable over time. The second structure of age proved extremely sensitive to any change. To use the matrix models is not a simple path of going over. In spite of the results, the matrix models joined to ample experience of the observer would be able to present proposals of sustainable handling of the forestal resources.

  6. Subfossil markers of climate change during the Roman Warm Period of the late Holocene

    Science.gov (United States)

    Jach, Renata; Knutelski, Stanisław; Uchman, Alfred; Hercman, Helena; Dohnalik, Marek

    2018-02-01

    Abundant bog oak trunks occur in alluvial deposits of the Raba River in the village of Targowisko (southern Poland). Several of them contain galleries of the great capricorn beetle ( Cerambyx cerdo L.). A well-preserved subfossil larva and pupa, as well as adults of this species, are concealed in some of the galleries. These galleries co-occur with boring galleries of other insects such as ship-timber beetles (Lymexylidae) and metallic wood borers (Buprestidae). A dry larva of a stag beetle (Lucanidae) and a mite (Acari) have been found in the C. cerdo galleries. Selected samples of the trunks and a sample of the C. cerdo larva were dated, using radiocarbon and dendrochronological methods, to the period from 45 bc to ad 554; one sample was dated to the period from 799 to 700 bc. Accumulation of the channel alluvia containing the bog oak trunks is synchronous with the Roman Warm Period (late antiquity/Early Mediaeval times). The most recent part of this period correlates with massive accumulations of fallen oak trunks noted from various river valleys in the Carpathian region and dated to ad 450-570. The results indicate that C. cerdo was more abundant within the study area during the Roman Warm Period than it is today.

  7. Radiocarbon measurements of tree-ring samples from Japanese woods

    International Nuclear Information System (INIS)

    Ozaki, Hiromasa; Sakamoto, Minoru; Imamura, Mineo; Mitsutani, Takumi

    2008-01-01

    Since radiocarbon age is a model age based on constancy of atmospheric radiocarbon concentration and a provisional value of 5568 years for the 14 C half-life, calibration to calendar age is required for practical dating. The dataset, called IntCal, used for the calibration has been constructed by international consortium. Most parts of the IntCal have been based on the measurement of radiocarbon in dendrochronologically dated tree-ring samples from woods in Europe and North America. Regional offsets, which are designed as differences of local atmospheric radiocarbon from IntCal, have been pointed out based on recent radiocarbon measurements for tree-ring samples from a few regions. We have also measured radiocarbon of tree-ring samples from Japanese woods in order to investigate regional offsets in Japan. In this study, radiocarbon measurements for tree-ring samples from three different Japanese woods at around AD500 were carried out. Consequently, differences from IntCal04 at around AD500 were confirmed, although no systematic offset are found. However, the results obtained in this study agree with the raw data used for construction of IntCal04. This could pose a question to calculation method of IntCal04. (author)

  8. Distilling allometric and environmental information from time series of conduit size: the standardization issue and its relationship to tree hydraulic architecture.

    Science.gov (United States)

    Carrer, Marco; von Arx, Georg; Castagneri, Daniele; Petit, Giai

    2015-01-01

    Trees are among the best natural archives of past environmental information. Xylem anatomy preserves information related to tree allometry and ecophysiological performance, which is not available from the more customary ring-width or wood-density proxy parameters. Recent technological advances make tree-ring anatomy very attractive because time frames of many centuries can now be covered. This calls for the proper treatment of time series of xylem anatomical attributes. In this article, we synthesize current knowledge on the biophysical and physiological mechanisms influencing the short- to long-term variation in the most widely used wood-anatomical feature, namely conduit size. We also clarify the strong mechanistic link between conduit-lumen size, tree hydraulic architecture and height growth. Among the key consequences of these biophysical constraints is the pervasive, increasing trend of conduit size during ontogeny. Such knowledge is required to process time series of anatomical parameters correctly in order to obtain the information of interest. An appropriate standardization procedure is fundamental when analysing long tree-ring-related chronologies. When dealing with wood-anatomical parameters, this is even more critical. Only an interdisciplinary approach involving ecophysiology, wood anatomy and dendrochronology will help to distill the valuable information about tree height growth and past environmental variability correctly. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  9. Many missing rings in old Canary pines can be related with age, fires and traditional uses

    International Nuclear Information System (INIS)

    Génova, M.; Santana, C.; Martínez, B.

    2017-01-01

    Aim and area of study: In the present paper we estimated the age of four monumental Pinus canariensis of Gran Canaria (Canary Islands, Spain) by means of tree-ring analysis. Many tree-ring series have been accurately studied and many missing rings have been determined. Material and methods: The trees were dead and the samples analysed were big disks. We measured numerous radii and crossdated the individual tree-ring series, paying particular attention to the existence and location of missing rings. We have distinguished between missing outer rings (MORs) and missing inner rings (MIRs) and analysed the possible causes of both. Main results: We determined an average of 8.8% total missing rings (MRs) for these long-lived trees, with a maximum of 96 MRs in a series of over 500. We have tried to establish a tree-ring chronology on Gran Canaria Island, also having the tree-ring series from Inagua site, but the long individual tree-ring series analysed do not crossdate between them. Research highlights: We consider the Canary pine a species hard to conducting dendroecological studies, especially if the samples come from managed old trees, in which a large amount of known and potentially unknown missing rings can hampered dating. Even knowing the difficulties involved in dendrochronological analyses of P. canariensis, we can confirm that it is a long-lived species, which can grow to over 500 years, and some of whose growth changes could be associated with certain historical and ecological events

  10. Radiation densitometry in tree-ring analysis: a review and procedure manual

    International Nuclear Information System (INIS)

    Parker, M.L.; Taylor, F.G.; Doyle, T.W.; Foster, B.E.; Cooper, C.; West, D.C.

    1985-01-01

    An x-ray densitometry of wood facility is being established by the Environmental Sciences Division, Oak Ridge Natioanl Laboratory (ORNL). The objective is to apply tree-ring data to determine whether or not there is a fertilizer effect on tree growth from increased atmospheric carbon dioxide since the beginning of the industrial era. Intra-ring width and density data, including ring-mass will be detemined from tree-ring samples collected from sites located throughout the United States and Canada. This report is designed as a guide to assist ORNL scientists in building the x-ray densitometry system. The history and development of x-ray densitometry in tree-ring research is examined and x-ray densitometry is compared with other techniques. Relative wood and tree characteristics are described as are environmental and genetic factors affecting tree growth responses. Methods in x-ray densitometry are examined in detail and the techniques used at four operating laboratories are described. Some ways that dendrochronology has been applied in dating, in wood quality, and environmental studies are presented, and a number of tree-ring studies in Canada are described. An annotated bibliography of radiation densitometry in tree-ring analysis and related subjects is included

  11. Assessing the Effects of Periodic Flooding on the Population Structure and Recruitment Rates of Riparian Tree Forests

    Directory of Open Access Journals (Sweden)

    Jean-Sébastien Berthelot

    2014-08-01

    Full Text Available Riparian forest stands are subjected to a variety of hydrological stresses as a result of annual fluctuations in water levels during the growing season. Spring floods create additional water-related stress as a result of a major inflow of water that floods riverside land. This exploratory study assesses the impacts of successive floods on tree dynamics and regeneration in an active sedimentation area, while determining the age of the stands using the recruitment rates, tree structure and tree rings based on dendrochronological analysis. Environmental data were also recorded for each vegetation quadrat. In total, 2633 tree stems were tallied throughout the quadrats (200 m2, and tree specimens were analyzed based on the various flood zones. A total of 720 specimens were counted (100 m2 strip to measure natural regeneration. Higher recruitment rates are noted for the no-flood zones and lower rates in active floodplains. During the period of the establishment of tree species, the survival rates are comparable between the flood zones and the no-flood zones. Tree diameter distribution reveals a strong predominance of young trees in flooded areas. Different factors appear to come into play in the dynamics of riparian forest stands, including the disruptions associated with successive flooding.

  12. Dynamics of nival and glacial slope processes in the Baksan and Teberda river basins from radiocarbon dating of buried soils

    Directory of Open Access Journals (Sweden)

    O. N. Solomina

    2013-01-01

    Full Text Available Radiocarbon and tree-ring dating of the soil horizons, buried in the slope and fluvioglacial deposits in Baksan and Teberda valleys, bring evidence of the reduction of the avalanche activity, stabilization of the slopes and soil formation on their surfaces. In the Baksan section three such horizons are identified, while in the Teberda section only one. The radiocarbon dates of the two thickest soil horizons in the Baksan section are 170±50 BP (1650–1890 CE and 380±60 BP (1430–1650 CE. The dendrochronological date of the wood (after 1677 in the upper layer of the buried soil horizon in the in the Dombai section probably indicate the increase of the river runoff and debris flow activity in relation with the glacier advance in the upperstream of Ammanauz river. However it is also close to the Terskoye earth quake occurred in 1688. The radiocarbon dates of the buried soils cluster in three groups (270–290, 340–440, 1280–1440 yrs BP. It is possible that their burial is connected to the climatic (increase in precipitation, especially extreme ones or seismic causes.

  13. Trace metal fluxes to ferromanganese nodules from the western Baltic Sea as a record for long-term environmental changes

    International Nuclear Information System (INIS)

    Hlawatsch, S.; Garbe-Schonberg, C.D.; Lechtenberg, F.; Manceau, A.; Tamura, N.; Kulik, D.A.; Suess, E.; Kersten, M.

    2002-01-01

    Trace element profiles in ferromanganese nodules from the western Baltic Sea were analyzed with laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) and synchrotron-based micro-X-ray radiation techniques (fluorescence: mSXRF, and diffraction: mXRD) at high spatial resolution in growth direction. Of the trace elements studied (Zn, Cu, Cd, Ni, Co, Mo, Ba), Zn showed the most significant enrichment, with values in the outermost surface layers of up to six-fold higher than those found in older core parts. The high-resolution Zn profiles provide the necessary temporal resolution for a dating method analogous to dendrochronology. Profiles in various samples collected during two decades were matched and the overlapping sections used for estimation of the accretion rates. Assuming a continuous accretion of these relatively fast growing nodules (on average 20 mm a-1) over the last century, the Zn enrichment was thus assessed to have commenced around 1860/70 in nodules from the Kiel Bight and in 1880/90 from Mecklenburg Bight, reflecting the enhanced heavy metal emissions with rising industrialization in Europe. Apart from the obvious success with Zn, only As and Co show significant but only 1.5-fold enrichments in the most recent growth layers of the nodules. Other anthropogenic trace metals like Cu and Cd are not at all enriched, which, together with the distinct early-diagenetic Fe/Mn banding, weakens the potential of the nodules for retrospective monitoring

  14. Strengthening Connections between Dendrohydrology and Water Management in the Mediterranean Basin

    Science.gov (United States)

    Touchan, R.; Freitas, R. J.

    2017-12-01

    Dendrochronology can provide the knowledge upon which to base sound decisions for water resources. In general, water managers are limited to using short continuous instrumental records for forecasting streamflows and reservoir levels. Longer hydrological records are required. Proxy data such as annual tree-ring growth provide us with knowledge of the past frequency and severity of climatic anomalies, such as drought and wet periods, and can be used to improve probability calculations of future events. By improving probability input to these plans, water managers can use this information for water allocations, water conservation measures, and water efficiency methods. Accurate planning is critical in water deficit regions with histories of conflict over land and limited water. Here, we link the science of dendrohydrology with water management, and identify appropriate forums for scientists, policy decision makers, and water managers to collaborate in translating science into effective actions anticipating extreme events, such drought or floods. We will present examples of several dendrohydrological reconstructions from the eastern Mediterranean and North Africa as input for water management plans. Different disciplines are needed to work together, and we identify possible mechanisms to collaborate in order to reach this crucial necessity to use scarce water wisely.

  15. Influence of repeated prescribed fire on tree growth and mortality in Pinus resinosa forests, northern Minnesota

    Science.gov (United States)

    Bottero, Alessandra; D'Amato, Anthony W.; Palik, Brian J.; Kern, Christel C.; Bradford, John B.; Scherer, Sawyer S.

    2017-01-01

    Prescribed fire is widely used for ecological restoration and fuel reduction in fire-dependent ecosystems, most of which are also prone to drought. Despite the importance of drought in fire-adapted forests, little is known about cumulative effects of repeated prescribed burning on tree growth and related response to drought. Using dendrochronological data in red pine (Pinus resinosa Ait.)-dominated forests in northern Minnesota, USA, we examined growth responses before and after understory prescribed fires between 1960 and 1970, to assess whether repeated burning influences growth responses of overstory trees and vulnerability of overstory tree growth to drought. We found no difference in tree-level growth vulnerability to drought, expressed as growth resistance, resilience, and recovery, between areas receiving prescribed fire treatments and untreated forests. Annual mortality rates during the period of active burning were also low (less than 2%) in all treatments. These findings indicate that prescribed fire can be effectively integrated into management plans and climate change adaptation strategies for red pine forest ecosystems without significant short- or long-term negative consequences for growth or mortality rates of overstory trees.

  16. Improved precision radiocarbon measurements and natural 14C variations around 10.000 cal BP

    International Nuclear Information System (INIS)

    Goslar, T.

    1990-01-01

    The subject of present work, natural radiocarbon variations in the past, is one of the most significant methodological questions of radiocarbon chronology. In the first three chapters, the author discusses problems connected with calibration of conventional radiocarbon dates, and consequences of monitoring the 14 C variations for the research of the changes of geomagnetic field, solar activity and global carbon cycle. Dendrochronological dating, which, in connection with 14 C measurements enables us to reconstruct the radiocarbon variations in the past, is also widely described. Fourth chapter concerns the technical problems of detection 14 C β-activity, especially accounting for proportional counters technique. In the next chapter the author describes results of his own dendrochonological research. Sixth chapter comprises frame discussion of the system for improved precision radiocarbon dating, together with short presentation of equipment, its calibration and analysis of errors. The last chapter gives the reconstruction of the pattern of atmospheric 14 C variations in 300-year period around 10.000 cal BP. It was found that in the last 10.000 years similar pattern repeats periodically. In the end, the author discusses the meaning of negative correlation between 14 C variations and changes of annual tree-ring widths in the oak trunk from Lublinek, for searching the connection between solar activity and climate. (author)

  17. Tree rings reveal a major episode of forest mortality in the late 18th century on the Tibetan Plateau

    Science.gov (United States)

    Fang, Ouya; Alfaro, René I.; Zhang, Qi-Bin

    2018-04-01

    There is a growing research interest on studying forest mortality in relation to ongoing climate warming, but little is known about such events in past history. The study of past forest mortality provides valuable information for determining baselines that establish the normal parameters of functioning in forest ecosystems. Here we report a major episode of previously undocumented forest mortality in the late 18th century on the northern Tibetan Plateau, China. The event was not spatially uniform, in which a more severe mortality happened in dryer sites. We used dendrochronology to compare radial growth trajectories of individual trees from 11 sites in the region, and found that many trees showed positive growth trend, or growth release, during 1796-1800 CE. Growth releases are a proxy indicator of stand thinning caused by tree mortality. The growth release was preceded by an almost two-decade long growth reduction. Long-term drought related to weakened North Atlantic Oscillation and frequent El Niño events are the likely factors causing the tree mortality in a large area of the plateau. Our findings suggest that, besides the effect of drought in the late 18th century, large-scale forest mortality may be an additional factor that further deteriorated the environment and increased the intensity of dust storms.

  18. Tree rings and rainfall in the equatorial Amazon

    Science.gov (United States)

    Granato-Souza, Daniela; Stahle, David W.; Barbosa, Ana Carolina; Feng, Song; Torbenson, Max C. A.; de Assis Pereira, Gabriel; Schöngart, Jochen; Barbosa, Joao Paulo; Griffin, Daniel

    2018-05-01

    The Amazon basin is a global center of hydroclimatic variability and biodiversity, but there are only eight instrumental rainfall stations with continuous records longer than 80 years in the entire basin, an area nearly the size of the coterminous US. The first long moisture-sensitive tree-ring chronology has been developed in the eastern equatorial Amazon of Brazil based on dendrochronological analysis of Cedrela cross sections cut during sustainable logging operations near the Rio Paru. The Rio Paru chronology dates from 1786 to 2016 and is significantly correlated with instrumental precipitation observations from 1939 to 2016. The strength and spatial scale of the precipitation signal vary during the instrumental period, but the Rio Paru chronology has been used to develop a preliminary reconstruction of February to November rainfall totals from 1786 to 2016. The reconstruction is related to SSTs in the Atlantic and especially the tropical Pacific, similar to the stronger pattern of association computed for the instrumental rainfall data from the eastern Amazon. The tree-ring data estimate extended drought and wet episodes in the mid- to late-nineteenth century, providing a valuable, long-term perspective on the moisture changes expected to emerge over the Amazon in the coming century due to deforestation and anthropogenic climate change.

  19. Exploring Historical Coffee and Climate Relations in Southern Guatemala: An Integration of Tree Ring Analysis and Remote Sensing Data =

    Science.gov (United States)

    Pons, Diego

    This dissertation makes use of a physical geography perspective to examine the relationship between agriculture and climate in Guatemala using dendrochronology. I examined the potential of high-resolution climate proxy data from dendrochronology to help fill in the gaps of past climate information to better understand the natural and anthropogenic variability of precipitation which, in turn, can inform Guatemala's agriculture sector. This research has demonstrated successful cross-dating and climate sensitivity of Abies guatemalensis in the Pacific slope of Guatemala. Based on this, I have produced a 124-year record of mean precipitation from June-July-August. The mean precipitation from June-July-August at this site seems to receive an important influence from the sea surface temperature (SST) in the Pacific Ocean in the form of El Nino-Southern Oscillation (ENSO) in the region 3.4. The analysis on the frequency of the precipitation records suggests that single year droughts dominate the record yet, periods of 9 years below-average rainfall can persist. Likewise, single year pluvial events also dominate the evaluated period. The long-term reconstruction of precipitation allowed to describe past relationships between coffee plantations and pests. For instance, the frequency analysis suggests that 4 or more consecutive periods of above-average precipitation are associated with several coffee pests and subsequently great economical losses due to crop failures, including the last coffee leaf rust crisis. This study also presents a streamflow reconstruction of the Upper Samala River watershed using a tree ring-width chronology derived from the Guatemalan fir (Abies guatemalensis) to reconstruct mean August-September-October streamflow volumes for the period 1889-2013. Our analysis shows that strong statistical correlations are present between tree-ring width measurements and monthly natural streamflow series. The mean August-September-October streamflow variability is

  20. The Growth of Bosnian Pine (Pinus hedreichii Christ. at Tree-Line Locations from Kosovo and its Response to Climate

    Directory of Open Access Journals (Sweden)

    Faruk Bojaxhi

    2016-12-01

    Full Text Available Background and Purpose: Pinus heldreichii Christ. is a sub-endemic species occurring at tree-line locations in Kosovo and covering an area of 2500 ha. In high elevation sites radial growth is mainly controlled by low temperatures. The main purpose of this study was the analysis of radial growth of P. heldreichii and its response to local climate conditions. Materials and Methods: Research sites comprise of three high elevation stands of P. heldreichii with specific site conditions. Core samples were collected from 98 healthy dominant and co-dominant trees at breast height using increment borer. They were prepared and cross-dated using standard dendrochronological methods, while tree-ring widths were measured to the nearest 0.001 mm using the TSAP software. The ARSTAN program was used to standardize the tree-ring widths and to calculate dendrochronological statistical parameters. The growth-climate relationship was investigated using bootstrapped correlation function analysing the residual chronologies of each sampled site as a dependent variable and the climatic data from May of the (n-1 year up to the October of the n year for the common period 1951-2013 as an independent variable. Results: The length of Bosnian pine chronologies ranged from 175 to 541 years. All chronologies had high values of first-order autocorrelation indicating that radial growth of P. heldreichii is affected by the climate conditions of the previous growing year. Koritnik chronology had the highest values of the mean sensitivity due to the influence of drought stress. This conclusion is also supported by the result of growth-climate relationship where radial growth is negatively correlated with June temperatures and positively associated with July and August precipitation. We found that radial growth of young trees from Koritnik site is limited by the combined effect of temperatures and summer drought stress. In high elevation sites, temperature is expected to control the

  1. Recent Relationships of Tree Establishment and Climate in Alpine Treelines of the Rocky Mountains

    Science.gov (United States)

    Germino, M. J.; Graumlich, L. J.; Maher, E. J.

    2007-12-01

    Changes in the forest structure of alpine-forest or treeline boundaries may be a significant climate response of mountainous regions in the near future. A particularly important point of climate sensitivity for treelines is the initial survival and establishment of tree seedlings - a demographic bottleneck that may be particularly suited to early detection of treeline responses to climate change. However, concise information on climate sensitivity of seedling establishment has come primarily from direct observations of seedlings over short time periods encompassing a few years. Dendrochronological approaches have revealed tree establishment patterns at more extensive time scales of decades to millenia, but at coarser temporal resolutions. Climate variations that most directly affect initial tree seedling establishment occur at annual or smaller time scales, and climate for seedlings is modulated by landscape factors such as neighboring plant cover. Our objective was to assess climate sensitivity of tree establishment at treeline at these finer temporal and spatial scales, with consideration of treeline features that alter the climate for seedlings. Our approach combined direct observations of seedling emergence and survival with dendrochronology of older seedlings and saplings that were still small and young enough (less than 25 years and 20 cm height) to allow detecting the year of establishment and associated factors. Surveys for subject seedlings and saplings were performed for 2 years across the gradient from forest into treeline alpine in the Beartooth, Teton, and Medicine Bow mountains of Wyoming USA. No seedlings or saplings were detected above the highest elevation adult trees or krummholz, but there were up to 0.3 seedlings per square meter in subalpine meadows close to forest (within the timberline zone) where changes in tree abundance appear possible in future decades. Correlations of establishment and summer temperature ranged from weak in whitebark

  2. Long term monitoring system integrated in an elevational gradient in NW Argentina

    Science.gov (United States)

    Carilla, J.; Malizia, A.; Osinaga, O.; Blundo, C.; Grau, R.; Malizia, L.; Aráoz, E.

    2013-05-01

    Ecological trends and ranges of variability are poorly known in the tropical and subtropical Andes. Long term studies are powerful tools to detect the response of vegetation dynamics, biodiversity and hydrological cycle to these trends. We present a long term monitoring system in NW Argentinean mountains, including forest permanent plots at different elevations and high elevation grasslands, encompassing more than 3.000 m elevation range. Long term studies include: 1) 66 ha of mountain forest permanent plots along the Yungas elevational gradient from c. 400 to 2500 masl , and latitudinal gradient (22-28S) with 45 plots in mature forests and 28 in secondary forests originated in grazing, agriculture and selective logging. Some of these permanent plots have achieved 20 years of monitoring and all of them are included in the "Red de Bosques Andinos" a network created recently, together with c. 10 institutions and more than 130 (c. 120 ha) forest permanent plots from Argentina to Colombia Andes. 2) Two GLORIA (Global Observation Research Initiative in Alpine Environments) sites, above 4000 masl with more than 170 species recorded, including one re-measurement. This system is included in GLORIA network (www.gloria.ac.at) and in GLORIA Andes (http://www.condesan.org/gloria), and 3) more than 15 satellite monitored high Andean lakes and a wide extension of vegas (75800 ha in Argentinean puna). A digital database is being implemented to organize and provide access to the information generated by these three systems coordinated by the Instituto de Ecología Regional (http://www.iecologia.com.ar). These monitoring data are analyzed together with instrumental and dendrochronological data to describe the dynamics of these ecosystems over an area of 20 million hectares distributed between 22 and 28°S. Some of the most significant results to date include: 1) secondary mountain forests are expanding over grasslands and agriculture lands, and tend to converge toward mature forest

  3. La charpente de la nef de la cathédrale de Bourges The structure of the nave in Bourges cathedral

    Directory of Open Access Journals (Sweden)

    Frédéric Epaud

    2012-03-01

    the removal of the false transept and its spire. The archaeological survey of the structure remaining on the Gothic nave, and the dendrochronological analysis of its timber shows that the trees were felled over a period from 1230 to 1257, with two major felling campaigns between 1240 and 1244 and autumn-winter 1254-1255, just prior to the implementation and lifting of the structure in 1256 or soon after. These successive fellings suggest a supply to the site from donations of wood or forest plots used immediately, requiring the storage of wood pending construction. The trussed rafter structure was built according to a first plan that was modified while construction was underway to insert a longitudinal bracing device, with a new structure of main trusses to support it. This axial bracing was doubled by a second situated in the plane of the rafters, with a date, proven by dendrochronology for the first time, in the middle of the thirteenth century. In 1262 the eastern bays of the structure of the nave were changed to enable the addition of a wooden spire and a false transept directly below the fourth arch span.

  4. Cascading ecohydrological transitions: Multiple changes in vegetation and hydrology over the past 500 years for a semiarid forest/woodland boundary zone in New Mexico, USA

    Science.gov (United States)

    Allen, Craig D.

    2010-05-01

    On decadal and centennial time scales, multiple drivers can cause substantial changes in vegetation cover, which can trigger associated changes in runoff and erosion patterns and processes, with consequent feedbacks to the vegetation - cumulatively this can lead to a cascading series of non-equilibrial ecosystem changes through time. The work reported here provides a relatively detailed 500-year perspective of such changes on the mesas the eastern Jemez Mountains in northern New Mexico (USA), which today exhibit vegetation transitions along an elevational gradient between semiarid ponderosa pine (Pinus ponderosa) forests, mixed woodlands dominated by piñon (Pinus edulis) and one-seed juniper (Juniperus monosperma), and juniper savannas. Using multiple lines of evidence, a history of major ecosystem changes since ca. 1500 A.D. is reconstructed for a dynamic transition zone on one such mesa (Frijolito Mesa). Evidence includes intensive archaeological surveys, dendrochronological reconstructions of the demographic and spatial patterns of establishment and mortality for these three main tree species, dendrochronological reconstructions of fire regimes and climate patterns, broad-scale mapping of vegetation changes from historic aerial photographs since 1935, monitoring of vegetation from permanent transects since 1991, detailed soil maps and interpretations, intensive ecohydrological studies since 1993 on portions of this mesa, and research on the ecosystem effects of an experimental tree-thinning experiment conducted in 1997. Frijolito Mesa was fully occupied by large numbers of Native American farmers from the A.D. 1200's until the late 1500's, when they left these mesas for settlements in the adjoining Rio Grande Valley. Archaeological evidence and tree ages indicate that the mesa was likely quite deforested when abandoned, followed by episodic tree establishment dominated by ponderosa pine during the Little Ice Age. By the late 1700's Frijolito Mesa included

  5. Chemo-ecological studies on plant indicators for low level air pollution

    Energy Technology Data Exchange (ETDEWEB)

    Katoh, Terutaka; Kasuya, Minoru; Kagamimori, Sadanobu (Toyama Medical and Pharmaceutical Univ. (Japan). Faculty of Medicine); Kozuka, Hiroshi; Kawano, Shoichi

    1991-05-01

    The effects of low level air pollution on Japanese Cedar (Cryptomeria japonica) have been studied in the surrounding area of two thermoelectric power stations newly constructed in a rural area, Fukui Prefecture, on the Japan Sea side of central Honshu, Japan. The degree of visual injury in Japanese Cedar, scored with six different categories, was examined in 1974 and 1977 respectively, covering the entire study area. A more complete monitoring has been conducted at eight permanent sites in Awara-cho since 1974. A dendrochronological study was also carried out to evaluate the effects of air pollution on the increment growth of Japanese Cedars. There were clear correlations between the distance from the power station and tree decline. Severe damage was observed, in general, within a 7 km radius from the power station. The localized injury of Japanese Cedar, along the flood plain of the two rivers, was also demonstrated. A rapid increase of injury was noted until through the late 1970's. The growth inhibition, during this period, was also revealed by tree ring analysis. Some recovery of tree vigor and increment growth was observed after the introduction of pollution control systems at the power station. Consistent relationships were demonstrated between the index of increment growth, i.e., standardized ring index, and the levels of SO{sub 2} and NO{sub 2}. Scarcely any correlation was observed between pH of rain water and the standardized ring index. Decreased levels of foliar tannin were observed in the Japanese Cedars growing in the polluted areas. The inhibition of the shikimate pathway, by air pollution, was suggested by biochemical studies. Increased predation damage was observed in the foliage of Japanese Cedars with low tannin levels. The predisposed effects of air pollution were discussed with special reference to the inhibition of the shikimate pathway. (author).

  6. Increased spruce tree growth in Central Europe since 1960s.

    Science.gov (United States)

    Cienciala, Emil; Altman, Jan; Doležal, Jiří; Kopáček, Jiří; Štěpánek, Petr; Ståhl, Göran; Tumajer, Jan

    2018-04-01

    Tree growth response to recent environmental changes is of key interest for forest ecology. This study addressed the following questions with respect to Norway spruce (Picea abies, L. Karst.) in Central Europe: Has tree growth accelerated during the last five decades? What are the main environmental drivers of the observed tree radial stem growth and how much variability can be explained by them? Using a nationwide dendrochronological sampling of Norway spruce in the Czech Republic (1246 trees, 266 plots), novel regional tree-ring width chronologies for 40(±10)- and 60(±10)-year old trees were assembled, averaged across three elevation zones (break points at 500 and 700m). Correspondingly averaged drivers, including temperature, precipitation, nitrogen (N) deposition and ambient CO 2 concentration, were used in a general linear model (GLM) to analyze the contribution of these in explaining tree ring width variability for the period from 1961 to 2013. Spruce tree radial stem growth responded strongly to the changing environment in Central Europe during the period, with a mean tree ring width increase of 24 and 32% for the 40- and 60-year old trees, respectively. The indicative General Linear Model analysis identified CO 2 , precipitation during the vegetation season, spring air temperature (March-May) and N-deposition as the significant covariates of growth, with the latter including interactions with elevation zones. The regression models explained 57% and 55% of the variability in the two tree ring width chronologies, respectively. Growth response to N-deposition showed the highest variability along the elevation gradient with growth stimulation/limitation at sites below/above 700m. A strong sensitivity of stem growth to CO 2 was also indicated, suggesting that the effect of rising ambient CO 2 concentration (direct or indirect by increased water use efficiency) should be considered in analyses of long-term growth together with climatic factors and N

  7. Water temperature and fish growth: otoliths predict growth patterns of a marine fish in a changing climate.

    Science.gov (United States)

    Rountrey, Adam N; Coulson, Peter G; Meeuwig, Jessica J; Meekan, Mark

    2014-08-01

    Ecological modeling shows that even small, gradual changes in body size in a fish population can have large effects on natural mortality, biomass, and catch. However, efforts to model the impact of climate change on fish growth have been hampered by a lack of long-term (multidecadal) data needed to understand the effects of temperature on growth rates in natural environments. We used a combination of dendrochronology techniques and additive mixed-effects modeling to examine the sensitivity of growth in a long-lived (up to 70 years), endemic marine fish, the western blue groper (Achoerodus gouldii), to changes in water temperature. A multi-decadal biochronology (1952-2003) of growth was constructed from the otoliths of 56 fish collected off the southwestern coast of Western Australia, and we tested for correlations between the mean index chronology and a range of potential environmental drivers. The chronology was significantly correlated with sea surface temperature in the region, but common variance among individuals was low. This suggests that this species has been relatively insensitive to past variations in climate. Growth increment and age data were also used in an additive mixed model to predict otolith growth and body size later this century. Although growth was relatively insensitive to changes in temperature, the model results suggested that a fish aged 20 in 2099 would have an otolith about 10% larger and a body size about 5% larger than a fish aged 20 in 1977. Our study shows that species or populations regarded as relatively insensitive to climate change could still undergo significant changes in growth rate and body size that are likely to have important effects on the productivity and yield of fisheries. © 2014 John Wiley & Sons Ltd.

  8. CO2 fertilization and enhanced drought resistance in Greek firs from Cephalonia Island, Greece.

    Science.gov (United States)

    Koutavas, Athanasios

    2013-02-01

    Growth-climate relationships were investigated in Greek firs from Ainos Mountain on the island of Cephalonia in western Greece, using dendrochronology. The goal was to test whether tree growth is sensitive to moisture stress, whether such sensitivity has been stable through time, and whether changes in growth-moisture relationships support an influence of atmospheric CO2 on growth. Regressions of tree-ring indices (ad 1820-2007) with instrumental temperature, precipitation, and Palmer Drought Severity Index (PDSI) indicate that growth is fundamentally limited by growing-season moisture in late spring/early summer, most critically during June. However, this simple picture obscures a pattern of sharply evolving growth-climate relationships during the 20th century. Correlations between growth and June temperature, precipitation, and PDSI were significantly greater in the early 20th century but later degraded and disappeared. By the late 20th-early 21st century, there remains no statistically significant relationship between moisture and growth implying markedly enhanced resistance to drought. Moreover, growth experienced a net increase over the last half-century culminating with a sharp spike in ad 1988-1990. This recent growth acceleration is evident in the raw ring-width data prior to standardization, ruling out artifacts from statistical detrending. The vanishing relationship with moisture and parallel enhancement of growth are all the more notable because they occurred against a climatic backdrop of increasing aridity. The results are most consistent with a significant CO2 fertilization effect operating through restricted stomatal conductance and improved water-use efficiency. If this interpretation is correct, atmospheric CO2 is now overcompensating for growth declines anticipated from drier climate, suggesting its effect is unusually strong and likely to be detectable in other up-to-date tree-ring chronologies from the Mediterranean. © 2012 Blackwell Publishing

  9. Otolith oxygen isotopes measured by high-precision secondary ion mass spectrometry reflect life history of a yellowfin sole (Limanda aspera).

    Science.gov (United States)

    Matta, Mary Elizabeth; Orland, Ian J; Ushikubo, Takayuki; Helser, Thomas E; Black, Bryan A; Valley, John W

    2013-03-30

    The oxygen isotope ratio (δ(18)O value) of aragonite fish otoliths is dependent on the temperature and the δ(18)O value of the ambient water and can thus reflect the environmental history of a fish. Secondary ion mass spectrometry (SIMS) offers a spatial-resolution advantage over conventional acid-digestion techniques for stable isotope analysis of otoliths, especially given their compact nature. High-precision otolith δ(18)O analysis was conducted with an IMS-1280 ion microprobe to investigate the life history of a yellowfin sole (Limanda aspera), a Bering Sea species known to migrate ontogenetically. The otolith was cut transversely through its core and one half was roasted to eliminate organic contaminants. Values of δ(18)O were measured in 10-µm spots along three transects (two in the roasted half, one in the unroasted half) from the core toward the edge. Otolith annual growth zones were dated using the dendrochronology technique of crossdating. Measured values of δ(18)O ranged from 29.0 to 34.1‰ (relative to Vienna Standard Mean Ocean Water). Ontogenetic migration from shallow to deeper waters was reflected in generally increasing δ(18)O values from age-0 to approximately age-7 and subsequent stabilization after the expected onset of maturity at age-7. Cyclical variations of δ(18)O values within juvenile otolith growth zones, up to 3.9‰ in magnitude, were caused by a combination of seasonal changes in the temperature and the δ(18)O value of the ambient water. The ion microprobe produced a high-precision and high-resolution record of the relative environmental conditions experienced by a yellowfin sole that was consistent with population-level studies of ontogeny. Furthermore, this study represents the first time that crossdating has been used to ensure the dating accuracy of δ(18)O measurements in otoliths. Copyright © 2013 John Wiley & Sons, Ltd.

  10. La grange seigneuriale de « l’hébergement » de Flux à Lailly-en-Val (Loiret au XIVe siècle

    Directory of Open Access Journals (Sweden)

    Daniel Bontemps

    2012-04-01

    Full Text Available La grange seigneuriale de Flux à Lailly-en-Val (Loiret est construite sur le lit majeur de la Loire en zone primitivement inondable. Transformée par les siècles, elle n’en conserve pas moins son pourtour d’origine et une charpente à fermes et pannes sur poteaux dont les bois ont été coupés vers 1320 (dendrochronologie. Grâce à des aveux du XIVe siècle, postérieurs d’un tiers de siècle à sa construction, on constate qu’elle occupait une situation à part dans « l’hébergement » de Flux. Son implantation près de Beaugency permettait de transporter la part des récoltes qui y étaient entreposées en peu de temps pour y être vendue.The seigniorial barn of Flux at Lailly-en-Val (Loiret was built on the main bed of the river Loire which, at the time, was liable to inundation. The building has been modified over the centuries but nonetheless conserves its original footprint and its original wooden trusses and purlins. These are supported by posts the timber of which, according to dendrochronological analysis, was cut in about 1320. In archival consents dating from the 14th century, a third of a century after the construction, it is possible to see how the barn occupied a peripheral situation in the ‘hébergement’, the lodging of Flux. Its location near Beaugency allowed for parts of the harvest to be rapidly stored in the barn prior to sale.

  11. Flood-promoted vessel formation in Prioria copaifera trees in the Darien Gap, Colombia.

    Science.gov (United States)

    López, Janeth; Del Valle, Jorge I; Giraldo, Jorge A

    2014-10-01

    Trees growing in floodplains develop mechanisms by which to overcome anoxic conditions. Prioria copaifera Griseb. grows on the floodplains of the Atrato River, Colombia, and monodominant communities of this species remain flooded for at least 6 months a year. The aims of this study were as follows: (i) to compare variations in tree-ring structure with varying river water levels; and (ii) to reconstruct variations in water levels from the chronology of variations in the porosity of the tree rings. Discs were taken from 12 trees, and the number of vessels along 3-mm-wide radial transects was counted. Standard dendrochronological techniques were used to determine the mean number of vessels over 130 years, between 1877 and 2006; the signal-to-noise ratio was 13.3 and the expressed population signal 0.93. Furthermore, this series of vessel numbers was calibrated against variations in the water levels between 1977 and 2000; positive correlations were found with the mean for both the annual river water level and the level from June to August. The transfer function between the principal components of the mean annual water level and those of chronology allowed us to reconstruct the river levels over 130 years. Our conclusions are as follows: (i) the number of vessels per ring is an appropriate proxy for determining variations in water levels; and (ii) P. copaifera grows thicker and produces more vessels when water levels rise. The probable ecophysiological causes of this interesting behaviour are discussed. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  12. Enhanced growth of Juniperus thurifera under a warmer climate is explained by a positive carbon gain under cold and drought.

    Science.gov (United States)

    Gimeno, Teresa E; Camarero, J Julio; Granda, Elena; Pías, Beatriz; Valladares, Fernando

    2012-03-01

    Juniperus thurifera L. is an endemic conifer of the western Mediterranean Basin where it is subjected to a severe climatic stress characterized by low winter temperatures and summer drought. Given the trend of increased warming-induced drought stress in this area and the climatic sensitivity of this species, we expect a negative impact of climate change on growth and ecophysiological performance of J. thurifera in the harsh environments where it dominates. To evaluate this, we measured long- and short-term radial growth using dendrochronology, photosynthesis and water-use efficiency in males, females and juveniles in three sites in Central Spain. Climate was monitored and completed with historical records. Mean annual temperature has increased +0.2 °C per decade in the study area, and the main warming trends corresponded to spring (+0.2 °C per decade) and summer (+0.3 °C per decade). Radial growth and maximum photosynthesis peaked in spring and autumn. Positive photosynthetic rates were maintained all year long, albeit at reduced rates in winter and summer. Radial growth was enhanced by wet conditions in the previous autumn and by warm springs and high precipitation in summer of the year of tree-ring formation. Cloud cover during the summer increased growth, while cloudy winters led to impaired carbon gain and reduced growth in the long term. We argue that maintenance of carbon gain under harsh conditions (low winter temperatures and dry summer months) and plastic xylogenesis underlie J. thurifera's ability to profit from changing climatic conditions such as earlier spring onset and erratic summer rainfall. Our results highlight that not only the magnitude but also the sign of the impact of climate change on growth and persistence of Mediterranean trees is species specific.

  13. Only one simple conclusion about the climate

    Energy Technology Data Exchange (ETDEWEB)

    Jaremko, G.

    2000-07-24

    Findings concerning climate change, by a three-man team of scientists from the North Dakota Geological Survey, which were presented in a paper read at the Eight International Williston Basin Horizontal Well Workshop, are discussed. The survey by the three scientists covered more than 6,000 scholarly publications. It reported that while the rise in the Earth's temperature is beyond argument, there is anything but agreement as to the causes, or whether the trend is unusual enough to justify concerted and costly actions to change lifestyles. It is shown by direct instrumental measurements that the average temperature at the Earth's surface increased about 0.8 degree Celsius between 1866 and 1998. During that time the concentration of carbon dioxide in the atmosphere increased from 280 to 353 parts per million. While it is generally assumed that the global warming was caused by human activities, new techniques of measurement such as glacier ice coring, dendrochronology (tree-growth rings), lichenometry (measuring the diameter of lichens) and counting concentrations of oxygen 18 and 16 (isotopes whose presence in marine fossils varies depending on temperature) suggest that most of the global warming took place before the increase in carbon dioxide concentration occurred, raising the possibility that the increase in average temperature had causes other than the increase in greenhouse gases. Some of the studies reviewed by the group show that in Europe between ice ages during the Eemian period, some 135,000 to 110,000 years ago, temperature variations of seven degrees Celsius took place; they dropped from two degree Celsius warmer than today to five degree Celsius colder than today. Based on these findings the group's only firm conclusion was that climate is in a continual flux.

  14. Spatial and temporal distribution of 14C in cellulose in tree rings in Central and Eastern Canada: comparison with long-term atmospheric and environmental data

    International Nuclear Information System (INIS)

    Kotzer, T.G.; Watson, W.L.

    1999-05-01

    Dendrochronologically characterized tree rings from several different species across Central and Eastern Canada and spanning a time range of several decades have been analysed for their 14 C specific activities using oxygen combustion - direct liquid scintillation counting techniques. Carbon-14 specific activities varied between 218 and 439 Bq·kg -1 (±5 to 10%) and yielded a good correlation with the 14 C measured in long-term records of 14 C-in-air values, although 14 C levels in Canada are slightly higher (10 to 20 per mil). An average pre-bomb 14 C value of 225 Bq·kg -1 was obtained from tree rings between 1910 and 1945 which agrees with the value for NBS oxalic acid standard for 'modern' 14 C at 226 Bq·kg -1 . Present-day levels of 14 C in the tree rings are on the order of 250 Bq·kg -1 , indicating that they, like 14 C0 2 -in-air values, have yet to reach 'pre-nuclear testing' levels. Specific activities of 14 C in tree rings from several sites in Canada show no systematic changes with respect to their distance from CANDU heavy-water nuclear power generating stations, suggesting that these stations have had negligible effects on the atmospheric radiocarbon budget for mid-latitudinal North America. The radiocarbon data from the tree rings indicate that atmospheric 14 C has an atmospheric half-time on the order of approximately 15 years, similar to that from other data sets. (author)

  15. Growth of teak regenerated by coppice and stump planting in Mae Moh Plantation, Lampang province, Thailand

    Directory of Open Access Journals (Sweden)

    Anatta Auykim

    2017-08-01

    Full Text Available The current annual increment (CAIdbh and the mean annual increment (MAIdbh both for the diameter at breast height (1.3 m were investigated to compare the differences between coppice and stump-planted teak in Mae Moh Plantation. Forty-eight sample cores were collected from a 9 yr-old teak plantation using an increment borer; annual increments were analyzed using dendrochronological techniques. The results indicated that there was no significant (p > 0.05 difference in the average diameter at breast height (DBH between the coppice and stump-planted teak, whereas the total height of stump planting was significantly greater than that of coppice teak. The CAIdbh of coppice teak was in the range 0.316–2.371 cm and continuously decreased throughout the 9 yr period. The CAIdbh of stump planting was in the range 0.162–1.982 cm and continuously increased from the beginning of growth for 5 yr followed by a decline thereafter for 4 yr. The CAIdbh of coppice showed rapid growth in the years 1–4 and was greater than for the stump-planted teak even in years 5–8 after planting; however, the growth of the stump-planted teak in the ninth year was higher than for the coppice. The MAIdbh values of coppice and stump-planted teak were not significantly (p > 0.05 different. The results showed that CAIdbh at age 5 yr can be used as a silvicultural guide to increase the yield of teak coppice.

  16. A wind proxy based on migrating dunes at the Baltic coast: statistical analysis of the link between wind conditions and sand movement

    Science.gov (United States)

    Bierstedt, Svenja E.; Hünicke, Birgit; Zorita, Eduardo; Ludwig, Juliane

    2017-07-01

    We statistically analyse the relationship between the structure of migrating dunes in the southern Baltic and the driving wind conditions over the past 26 years, with the long-term aim of using migrating dunes as a proxy for past wind conditions at an interannual resolution. The present analysis is based on the dune record derived from geo-radar measurements by Ludwig et al. (2017). The dune system is located at the Baltic Sea coast of Poland and is migrating from west to east along the coast. The dunes present layers with different thicknesses that can be assigned to absolute dates at interannual timescales and put in relation to seasonal wind conditions. To statistically analyse this record and calibrate it as a wind proxy, we used a gridded regional meteorological reanalysis data set (coastDat2) covering recent decades. The identified link between the dune annual layers and wind conditions was additionally supported by the co-variability between dune layers and observed sea level variations in the southern Baltic Sea. We include precipitation and temperature into our analysis, in addition to wind, to learn more about the dependency between these three atmospheric factors and their common influence on the dune system. We set up a statistical linear model based on the correlation between the frequency of days with specific wind conditions in a given season and dune migration velocities derived for that season. To some extent, the dune records can be seen as analogous to tree-ring width records, and hence we use a proxy validation method usually applied in dendrochronology, cross-validation with the leave-one-out method, when the observational record is short. The revealed correlations between the wind record from the reanalysis and the wind record derived from the dune structure is in the range between 0.28 and 0.63, yielding similar statistical validation skill as dendroclimatological records.

  17. Differential growth responses to water balance of coexisting deciduous tree species are linked to wood density in a Bolivian tropical dry forest.

    Science.gov (United States)

    Mendivelso, Hooz A; Camarero, J Julio; Royo Obregón, Oriol; Gutiérrez, Emilia; Toledo, Marisol

    2013-01-01

    A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability.

  18. Fast geomagnetic Field Intensity Variations between 1400 and 400 BCE: New Archaeointensity Data from Germany

    Science.gov (United States)

    Hervé, G.; Schnepp, E.; Metzler-Nebelsick, C.; Lhuillier, F.; Gilder, S.; Genevey, A.; Fassbinder, J.; Gallet, Y.

    2017-12-01

    Thirty-five mean archaeointensity data were obtained on ceramic sherds dated between 1400 and 400 BCE from sites located near Munich, Germany. The 453 sherds were collected from 52 graves, pits and wells dated by archaeological correlation, radiocarbon and/or dendrochronology. Rock magnetic analyses indicate that the remanent magnetization was mainly carried by magnetite. Data from Thellier-Thellier experiments were corrected for anisotropy and cooling rate effects. Triaxe and multispecimen (MSP-DSC) protocols were also measured on a subset of specimens. Around 60% of the samples provide reliable results when using stringent criteria selection. The 35 average archaeointensity values based on 154 pots are consistent with previous data and triple the Western Europe database between 1400 and 400 BCE. A secular variation curve for central-western Europe, built using a Bayesian approach, shows a double oscillation in geomagnetic field strength with intensity maxima of 70 μT around 1000-900 BCE and another up to 90 μT around 600-500 BCE. The maximum rate of variation was 0.25 μT/yr circa 700 BCE. The secular variation trend in Western Europe is similar to that observed in the Middle East and the Caucasus except that we find no evidence for hyper-rapid field variations (i.e. geomagnetic spikes). Virtual Axial Dipole Moments from Western Europe, the Middle East and central Asia differ by more than 20 ZA·m2 prior to 600 BCE, which signifies a departure from an axial dipole field especially between 1000 and 600 BCE. Our observations suggest that the regional Levantine Iron Age anomaly has been accompanied by an increase of the axial dipole moment together with a tilt of the dipole.

  19. Central Vietnam climate over the past five centuries from cypress tree rings

    Science.gov (United States)

    Buckley, Brendan M.; Stahle, Daniel K.; Luu, Hong Truong; Wang, S.-Y. Simon; Nguyen, Tran Quoc Trung; Thomas, Philip; Le, Canh Nam; Ton, That Minh; Bui, The Hoang; Nguyen, Van Thiet

    2017-06-01

    We present the first crossdated tree ring record from central Vietnam, derived from the growth rings of the rare cypress Fokienia hodginsii from the mountains of Quang Nam Province near the Laos border. The Quang Nam Fokienia hodginsii time series (QNFH), based on the crossdated sequences of 71 increment core samples from 37 mature trees, is the third published dendrochronological record from this species. The record extends 667 years from AD 1347 to 2013 and exhibits a mean series intercorrelation of 0.526, similarly significant with the first two published Fokienia hodginsii records: 0.474 for Mu Cang Chai (MCFH) and 0.578 for Bidoup-Nui Ba National Park (BDFH) in the north and south of Vietnam, respectively. The Expressed Population Signal (EPS) for the QNFH record exceeds the generally accepted threshold of 0.85 back to AD 1567, but remains above 0.8 back to 1550. Similar to the MCFH and BDFH records, QNFH expresses statistically significant linkages to regional hydroclimate metrics and the El Niño-Southern Oscillation. Here we present a reconstruction of the Standardized Precipitation Evapotranspiration Index for the month of April, averaged over a large region of Southeast Asia. As with prior studies we demonstrate that cool phase (La Niña) and warm phase (El Niño) events are linked to regional wet and dry conditions, respectively, with linkages to modulation of the surface water temperature over the adjacent sea to the east of Vietnam as well as the Indian Ocean. A late eighteenth century megadrought that is expressed widely across South and Southeast Asia, and notably from the MCFH and BDFH records described above, is not as pronounced in Central Vietnam and we explore the reasons why.

  20. Contamination risk of stable isotope samples during milling.

    Science.gov (United States)

    Isaac-Renton, M; Schneider, L; Treydte, K

    2016-07-15

    Isotope analysis of wood is an important tool in dendrochronology and ecophysiology. Prior to mass spectrometry analysis, wood must be homogenized, and a convenient method involves a ball mill capable of milling samples directly in sample tubes. However, sample-tube plastic can contaminate wood during milling, which could lead to biological misinterpretations. We tested possible contamination of whole wood and cellulose samples during ball-mill homogenization for carbon and oxygen isotope measurements. We used a multi-factorial design with two/three steel milling balls, two sample amounts (10 mg, 40 mg), and two milling times (5 min, 10 min). We further analyzed abrasion by milling empty tubes, and measured the isotope ratios of pure contaminants. A strong risk exists for carbon isotope bias through plastic contamination: the δ(13) C value of polypropylene deviated from the control by -6.77‰. Small fibers from PTFE filter bags used during cellulose extraction also present a risk as the δ(13) C value of this plastic deviated by -5.02‰. Low sample amounts (10 mg) showed highest contamination due to increased abrasion during milling (-1.34‰), which is further concentrated by cellulose extraction (-3.38‰). Oxygen isotope measurements were unaffected. A ball mill can be used to homogenize samples within test tubes prior to oxygen isotope analysis, but not prior to carbon or radiocarbon isotope analysis. There is still a need for a fast, simple and contamination-free sample preparation procedure. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  1. High Arctic summer warming tracked by increased Cassiope tetragona growth in the world's northernmost polar desert.

    Science.gov (United States)

    Weijers, Stef; Buchwal, Agata; Blok, Daan; Löffler, Jörg; Elberling, Bo

    2017-11-01

    Rapid climate warming has resulted in shrub expansion, mainly of erect deciduous shrubs in the Low Arctic, but the more extreme, sparsely vegetated, cold and dry High Arctic is generally considered to remain resistant to such shrub expansion in the next decades. Dwarf shrub dendrochronology may reveal climatological causes of past changes in growth, but is hindered at many High Arctic sites by short and fragmented instrumental climate records. Moreover, only few High Arctic shrub chronologies cover the recent decade of substantial warming. This study investigated the climatic causes of growth variability of the evergreen dwarf shrub Cassiope tetragona between 1927 and 2012 in the northernmost polar desert at 83°N in North Greenland. We analysed climate-growth relationships over the period with available instrumental data (1950-2012) between a 102-year-long C. tetragona shoot length chronology and instrumental climate records from the three nearest meteorological stations, gridded climate data, and North Atlantic Oscillation (NAO) and Arctic Oscillation (AO) indices. July extreme maximum temperatures (JulT emx ), as measured at Alert, Canada, June NAO, and previous October AO, together explained 41% of the observed variance in annual C. tetragona growth and likely represent in situ summer temperatures. JulT emx explained 27% and was reconstructed back to 1927. The reconstruction showed relatively high growing season temperatures in the early to mid-twentieth century, as well as warming in recent decades. The rapid growth increase in C. tetragona shrubs in response to recent High Arctic summer warming shows that recent and future warming might promote an expansion of this evergreen dwarf shrub, mainly through densification of existing shrub patches, at High Arctic sites with sufficient winter snow cover and ample water supply during summer from melting snow and ice as well as thawing permafrost, contrasting earlier notions of limited shrub growth sensitivity to

  2. δ13C of Tree-Ring Lignin as an Indirect Measure of Climate Change

    International Nuclear Information System (INIS)

    Robertson, I.; Loader, N. J.; McCarroll, D.; Carter, A. H. C.; Cheng, L.; Leavitt, S. W.

    2004-01-01

    High-resolution paleoclimatic data are an essential requirement for testing numerical models of climate change and the global carbon cycle. If the long tree-ring chronologies, originally established for the purpose of dendrochronology, are to be fully exploited as an indirect measure of past climatic variability, additional techniques are required to obtain this information. The determination of the δ 13 C value of tree-ring cellulose has been used successfully to reconstruct past climates. However, under both aerobic and anaerobic conditions, the polysaccharide components of vascular plants (mainly cellulose and hemicelluloses) are more prone to rapid degradation than lignin. This has serious implications for the use of carbon isotope values of tree-ring cellulose as an indirect measure of past climates. An absolutely dated ring-width chronology was established for oaks (Quercus robur L.) growing at Sandringham Park in eastern England. Carbon isotope values were determined on α-cellulose and 'Klason' lignin isolated from annual latewood samples over the period AD 1895-1999. The carbon isotope values of earlywood lignin are correlated with the latewood carbon isotope values of the previous year, supporting the theory that some of the carbon utilised in earlywood synthesis is assimilated in the previous year. The high-frequency variance in the carbon isotope indices of latewood lignin and cellulose is highly correlated with combined July and August environmental variables, indicating that they were formed at similar times. There was no evidence of secondary lignification. These results demonstrate that the determination of carbon isotope values of latewood lignin offers the potential to obtain unambiguous proxy climatic data covering several millennia

  3. Strong evidence for changing fish reproductive phenology under climate warming on the Tibetan Plateau.

    Science.gov (United States)

    Tao, Juan; He, Dekui; Kennard, Mark J; Ding, Chengzhi; Bunn, Stuart E; Liu, Chunlong; Jia, Yintao; Che, Rongxiao; Chen, Yifeng

    2018-05-01

    Phenological responses to climate change have been widely observed and have profound and lasting effects on ecosystems and biodiversity. However, compared to terrestrial ecosystems, the long-term effects of climate change on species' phenology are poorly understood in aquatic ecosystems. Understanding the long-term changes in fish reproductive phenology is essential for predicting population dynamics and for informing management strategies, but is currently hampered by the requirement for intensive field observations and larval identification. In this study, a very low-frequency sampling of juveniles and adults combined with otolith measurements (long axis length of the first annulus; LAFA) of an endemic Tibetan Plateau fish (Gymnocypris selincuoensis) was used to examine changes in reproductive phenology associated with climate changes from the 1970s to 2000s. Assigning individual fish to their appropriate calendar year class was assisted by dendrochronological methods (crossdating). The results demonstrated that LAFA was significantly and positively associated with temperature and growing season length. To separate the effects of temperature and the growing season length on LAFA growth, measurements of larval otoliths from different sites were conducted and revealed that daily increment additions were the main contributor (46.3%), while temperature contributed less (12.0%). Using constructed water-air temperature relationships and historical air temperature records, we found that the reproductive phenology of G. selincuoensis was strongly advanced in the spring during the 1970s and 1990s, while the increased growing season length in the 2000s was mainly due to a delayed onset of winter. The reproductive phenology of G. selincuoensis advanced 2.9 days per decade on average from the 1970s to 2000s, and may have effects on recruitment success and population dynamics of this species and other biota in the ecosystem via the food web. The methods used in this study

  4. Millennium-scale crossdating and inter-annual climate sensitivities of standing California redwoods.

    Science.gov (United States)

    Carroll, Allyson L; Sillett, Stephen C; Kramer, Russell D

    2014-01-01

    Extremely decay-resistant wood and fire-resistant bark allow California's redwoods to accumulate millennia of annual growth rings that can be useful in biological research. Whereas tree rings of Sequoiadendron giganteum (SEGI) helped formalize the study of dendrochronology and the principle of crossdating, those of Sequoia sempervirens (SESE) have proven much more difficult to decipher, greatly limiting dendroclimatic and other investigations of this species. We overcame these problems by climbing standing trees and coring trunks at multiple heights in 14 old-growth forest locations across California. Overall, we sampled 1,466 series with 483,712 annual rings from 120 trees and were able to crossdate 83% of SESE compared to 99% of SEGI rings. Standard and residual tree-ring chronologies spanning up to 1,685 years for SESE and 1,538 years for SEGI were created for each location to evaluate crossdating and to examine correlations between annual growth and climate. We used monthly values of temperature, precipitation, and drought severity as well as summer cloudiness to quantify potential drivers of inter-annual growth variation over century-long time series at each location. SESE chronologies exhibited a latitudinal gradient of climate sensitivities, contrasting cooler northern rainforests and warmer, drier southern forests. Radial growth increased with decreasing summer cloudiness in northern rainforests and a central SESE location. The strongest dendroclimatic relationship occurred in our southernmost SESE location, where radial growth correlated negatively with dry summer conditions and exhibited responses to historic fires. SEGI chronologies showed negative correlations with June temperature and positive correlations with previous October precipitation. More work is needed to understand quantitative relationships between SEGI radial growth and moisture availability, particularly snowmelt. Tree-ring chronologies developed here for both redwood species have

  5. {delta}{sup 13}C of Tree-Ring Lignin as an Indirect Measure of Climate Change

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, I. [CSIR Environmentek, Quaternary Dating Research Unit (South Africa)], E-mail: i.robertson@swansea.ac.uk; Loader, N. J.; McCarroll, D. [University of Wales Swansea, Department of Geography (United Kingdom); Carter, A. H. C. [University of Cambridge, Godwin Institute for Quaternary Research (United Kingdom); Cheng, L.; Leavitt, S. W. [University of Arizona, Laboratory of Tree-Ring Research (United States)

    2004-06-15

    High-resolution paleoclimatic data are an essential requirement for testing numerical models of climate change and the global carbon cycle. If the long tree-ring chronologies, originally established for the purpose of dendrochronology, are to be fully exploited as an indirect measure of past climatic variability, additional techniques are required to obtain this information. The determination of the {delta}{sup 13}C value of tree-ring cellulose has been used successfully to reconstruct past climates. However, under both aerobic and anaerobic conditions, the polysaccharide components of vascular plants (mainly cellulose and hemicelluloses) are more prone to rapid degradation than lignin. This has serious implications for the use of carbon isotope values of tree-ring cellulose as an indirect measure of past climates. An absolutely dated ring-width chronology was established for oaks (Quercus robur L.) growing at Sandringham Park in eastern England. Carbon isotope values were determined on {alpha}-cellulose and 'Klason' lignin isolated from annual latewood samples over the period AD 1895-1999. The carbon isotope values of earlywood lignin are correlated with the latewood carbon isotope values of the previous year, supporting the theory that some of the carbon utilised in earlywood synthesis is assimilated in the previous year. The high-frequency variance in the carbon isotope indices of latewood lignin and cellulose is highly correlated with combined July and August environmental variables, indicating that they were formed at similar times. There was no evidence of secondary lignification. These results demonstrate that the determination of carbon isotope values of latewood lignin offers the potential to obtain unambiguous proxy climatic data covering several millennia.

  6. Stand-structural effects on Heterobasidion abietinum-related mortality following drought events in Abies pinsapo.

    Science.gov (United States)

    Linares, Juan Carlos; Camarero, Jesús Julio; Bowker, Matthew A; Ochoa, Victoria; Carreira, José Antonio

    2010-12-01

    Climate change may affect tree-pathogen interactions. This possibility has important implications for drought-prone forests, where stand dynamics and disease pathogenicity are especially sensitive to climatic stress. In addition, stand structural attributes including density-dependent tree-to-tree competition may modulate the stands' resistance to drought events and pathogen outbreaks. To assess the effects of stand structure on root-rot-related mortality after severe droughts, we focused on Heterobasidion abietinum mortality in relict Spanish stands of Abies pinsapo, a drought-sensitive fir. We compared stand attributes and tree spatial patterns in three plots with H. abietinum root-rot disease and three plots without root-rot. Point-pattern analyses were used to investigate the scale and extent of mortality patterns and to test hypotheses related to the spread of the disease. Dendrochronology was used to date the year of death and to assess the association between droughts and growth decline. We applied a structural equation modelling approach to test if tree mortality occurs more rapidly than predicted by a simple distance model when trees are subjected to high tree-to-tree competition and following drought events. Contrary to expectations of drought mortality, the effect of precipitation on the year of death was strong and negative, indicating that a period of high precipitation induced an earlier tree death. Competition intensity, related to the size and density of neighbour trees, also induced an earlier tree death. The effect of distance to the disease focus was negligible except in combination with intensive competition. Our results indicate that infected trees have decreased ability to withstand drought stress, and demonstrate that tree-to-tree competition and fungal infection act as predisposing factors of forest decline and mortality.

  7. Relationships between climate and growth of Gymnocypris selincuoensis in the Tibetan Plateau.

    Science.gov (United States)

    Tao, Juan; Chen, Yifeng; He, Dekui; Ding, Chengzhi

    2015-04-01

    The consequences of climate change are becoming increasingly evident in the Tibetan Plateau, represented by glaciers retreating and lakes expanding, but the biological response to climate change by plateau-lake ecosystems is poorly known. In this study, we applied dendrochronology methods to develop a growth index chronology with otolith increment widths of Selincuo naked carp (Gymnocypris selincuoensis), which is an endemic species in Lake Selincuo (4530 m), and investigated the relationships between fish growth and climate variables (regional and global) in the last three decades. A correlation analysis and principle component regression analysis between regional climate factors and the growth index chronology indicated that the growth of G. selincuoensis was significantly and positively correlated with length of the growing season and temperature-related variables, particularly during the growing season. Most of global climate variables, which are relevant to the Asian monsoon and the midlatitude westerlies, such as El Nino Southern Oscillation Index, the Arctic Oscillation, North Atlantic Oscillation, and North America Pattern, showed negative but not significant correlations with the annual growth of Selincuo naked carp. This may have resulted from the high elevation of the Tibetan Plateau and the high mountains surrounding this area. In comparison, the Pacific Decade Oscillation (PDO) negatively affected the growth of G. selincuoensis. The reason maybe that enhancement of the PDO can lead to cold conditions in this area. Taken together, the results indicate that the Tibetan Plateau fish has been affected by global climate change, particularly during the growing season, and global climate change likely has important effects on productivity of aquatic ecosystems in this area.

  8. Compton suppression system at Penn State Radiation Science and Engineering Center

    International Nuclear Information System (INIS)

    Cetiner, N.Oe.; Uenlue, K.; Brenizer, J.S.

    2008-01-01

    A Compton suppression system is used to reduce the contribution of scattered gamma-rays that originate within the HPGe detector to the gamma ray spectrum. The HPGe detector is surrounded by an assembly of guard detectors, usually NaI(Tl). The HPGe and NaI(Tl) detectors are operated in anti-coincidence mode. The NaI(Tl) guard detector detects the photons that Compton scatter within, and subsequently escape from the HPGe detector. Since these photons are correlated with the partial energy deposition within the detector, much of the resulting Compton continuum can be subtracted from the spectrum reducing the unwanted background in gamma-ray spectra. A commercially available Compton suppression spectrometer (CSS) was purchased from Canberra Industries and tested at the Radiation Science and Engineering Center at Penn State University. The PSU-CSS includes a reverse bias HPGe detector, four annulus NaI(Tl) detectors, a NaI(Tl) plug detector, detector shields, data acquisition electronics, and a data processing computer. The HPGe detector is n-type with 54% relative efficiency. The guard detectors form an annulus with 9-inch diameter and 9-inch height, and have a plug detector that goes into/out of the annulus with the help of a special lift apparatus to raise/lower. The detector assembly is placed in a shielding cave. State-of-the-art electronics and software are used. The system was tested using standard sources, neutron activated NIST SRM sample and Dendrochronologically Dated Tree Ring samples. The PSU-CSS dramatically improved the peak-to-Compton ratio, up to 1000 : 1 for the 137 Cs source. (author)

  9. An evaluation of Mesodon and other larger terrestrial gastropod shells for dating late Holocene and historic alluvium in the Midwestern USA

    Science.gov (United States)

    Rakovan, Monica T.; Rech, Jason A.; Pigati, Jeffery S.; Nekola, Jeffery C.; Wiles, Gregory C.

    2013-01-01

    Understanding the history of stream erosion and changes in channel morphology is important for managing and restoring unstable streams. One of the significant challenges in this type of research is establishing accurate dating of late Holocene and historic alluvium. Here we evaluate the potential of using 14C dating and amino acid racemization (AAR) to date large terrestrial gastropod shells that are often preserved within alluvial sediments. Many terrestrial gastropods incorporate old carbon from limestone or other carbonate rocks into their shells and therefore are unsuitable for radiocarbon dating. Recent studies, however, have shown that some taxa avoid this ‘limestone problem’ and can yield reliable 14C ages. In this study, we measured the 14C activity of specimens for the genera Mesodon, Ventridens, and Allogona collected live and from alluvial sequences dated independently by dendrochronology, 14C dating of wood, and/or 137Cs analyses. Mesodon zaletus contained old carbon in similar concentrations (up to ~ 30%) found in previous studies of other large taxa and should be avoided for 14C dating when possible. In contrast, shells of Ventridens ligera and Allogona profunda showed minimal limestone effects and therefore may be suitable for dating late Holocene alluvium. These results highlight the importance of taxonomic identification of gastropod taxa prior to their use for 14C dating and demonstrate that shell fragments that are not identifiable should be avoided. We also measured d/l ratios (n = 17) of aspartic and glutamic acid from eight different taxa of terrestrial gastropods recovered from four late Holocene and historic stratigraphic sequences. Average d/l ratios of aspartic and glutamic acid from historic sediments < 300 years old are lower in shells from younger stratigraphic units, indicating that AAR can be used to differentiate between multiple historic stratigraphic units.

  10. Mistletoe effects on Scots pine decline following drought events: insights from within-tree spatial patterns, growth and carbohydrates.

    Science.gov (United States)

    Sangüesa-Barreda, Gabriel; Linares, Juan Carlos; Camarero, J Julio

    2012-05-01

    Forest decline has been attributed to the interaction of several stressors including biotic factors such as mistletoes and climate-induced drought stress. However, few data exist on how mistletoes are spatially arranged within trees and how this spatial pattern is related to changes in radial growth, responses to drought stress and carbon use. We used dendrochronology to quantify how mistletoe (Viscum album L.) infestation and drought stress affected long-term growth patterns in Pinus sylvestris L. at different heights. Basal area increment (BAI) trends and comparisons between trees of three different infestation degrees (without mistletoe, ID1; moderately infested trees, ID2; and severely infested trees, ID3) were performed using linear mixed-effects models. To identify the main climatic drivers of tree growth tree-ring widths were converted into indexed chronologies and related to climate data using correlation functions. We performed spatial analyses of the 3D distribution of mistletoe individuals and their ages within the crowns of three severely infested pines to describe their patterns. Lastly, we quantified carbohydrate and nitrogen concentrations in needles and sapwood of branches from severely infested trees and from trees without mistletoe. Mistletoe individuals formed strongly clustered groups of similar age within tree crowns and their age increased towards the crown apex. Mistletoe infestation negatively impacted growth but this effect was stronger near the tree apex than in the rest of sampled heights, causing an average loss of 64% in BAI (loss of BAI was ∼51% at 1.3 m or near the tree base). We found that BAI of severely infested trees and moderately or non-infested trees diverged since 2001 and such divergence was magnified by drought. Infested trees had lower concentrations of soluble sugars in their needles than non-infested ones. We conclude that mistletoe infestation causes growth decline and increases the sensitivity of trees to drought

  11. Assessment of tree response to drought: validation of a methodology to identify and test proxies for monitoring past environmental changes in trees.

    Science.gov (United States)

    Tene, A; Tobin, B; Dyckmans, J; Ray, D; Black, K; Nieuwenhuis, M

    2011-03-01

    A thinning experiment stand at Avoca, Ballinvalley, on the east coast of the Republic of Ireland was used to test a developed methodology aimed at monitoring drought stress, based on the analysis of growth rings obtained by coring. The stand incorporated six plots representing three thinning regimes (light, moderate and heavy) and was planted in the spring of 1943 on a brown earth soil. Radial growth (early- and latewood) was measured for the purpose of this study. A multidisciplinary approach was used to assess historic tree response to climate: specifically, the application of statistical tools such as principal component and canonical correlation analysis to dendrochronology, stable isotopes, ring density proxy, blue reflectance and forest biometrics. Results showed that radial growth was a good proxy for monitoring changes to moisture deficit, while maximum density and blue reflectance were appropriate for assessing changes in accumulated temperature for the growing season. Rainfall also influenced radial growth changes but not significantly, and was a major factor in stable carbon and oxygen discrimination, mostly in the latewood formation phase. Stable oxygen isotope analysis was more accurate than radial growth analysis in drought detection, as it helped detect drought signals in both early- and latewood while radial growth analysis only detected the drought signal in earlywood. Many studies have shown that tree rings provide vital information for marking past climatic events. This work provides a methodology to better identify and understand how commonly measured tree proxies relate to environmental parameters, and can best be used to characterize and pinpoint drought events (variously described using parameters such as like moisture deficit, accumulated temperature, rainfall and potential evaporation).

  12. Xylogenesis reveals the genesis and ecological signal of IADFs in Pinus pinea L. and Arbutus unedo L.

    Science.gov (United States)

    Balzano, A; Cufar, K; Battipaglia, G; Merela, M; Prislan, P; Aronne, G; De Micco, V

    2018-02-03

    Mediterranean trees have patterns of cambial activity with one or more pauses per year, leading to intra-annual density fluctuations (IADFs) in tree rings. We analysed xylogenesis (January 2015-January 2016) in Pinus pinea L. and Arbutus unedo L., co-occurring at a site on Mt. Vesuvius (southern Italy), to identify the cambial productivity and timing of IADF formation. Dendrochronological methods and quantitative wood anatomy were applied and enabled IADF identification and classification. We showed that cambium in P. pinea was productive throughout the calendar year. From January to March 2015, post-cambial (enlarging) earlywood-like tracheids were observed, which were similar to transition tracheids. The beginning of the tree ring was therefore not marked by a sharp boundary between latewood of the previous year and the new xylem produced. True earlywood tracheids were formed in April. L-IADFs were formed in autumn, with earlywood-like cells in latewood. In A. unedo, a double pause in cell production was observed, in summer and winter, leading to L-IADFs in autumn as well. Moreover, the formation of more than one IADF was observed in A. unedo. Despite having completely different wood formation models and different life strategies, the production of earlywood, latewood and IADF cells was strongly controlled by climatic factors in the two species. Such cambial production patterns need to be taken into account in dendroecological studies to interpret climatic signals in wood from Mediterranean trees. © The Author(s) 2018. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Growth decline assessment in Pinus sylvestris L. and Pinus nigra Arnold. forest by using 3-PG model

    Energy Technology Data Exchange (ETDEWEB)

    Navarro-Cerrillo, R.M.; Beira, J.; Suarez, J.; Xenakis, G.; Sánchez-Salguero, R.; Hernández-Clemente, R.

    2016-07-01

    Aim of the study: We assessed the ability of the 3-PG process-based model to accurately predict growth of Pinus sylvestris and P. nigra plantations across a range of sites, showing declining growth trends, in southern Spain. Area of study: The study area is located in “Sierra de Los Filabres” (Almería). Material and methods: The model was modified in fifteen parameters to predict diameter (DBH, cm), basal area increment (BAI, cm2 yr-1) and leaf area index (LAI, m2 m-2) in healthy trees and trees showing declining growth. We assumed that a set of specific physiological parameters (stem partitioning ratio-pFS20, maximum litterfall rate-γFx, maximum canopy conductance-gCx, specific leaf area for mature aged stands-σ1, age at which specific leaf area = ½ (σ0 + σ1), age at full canopy cover-tc, and canopy boundary layer conductance-gB) included in 3-PG would be suitable for predicting growth decline related to climate conditions. The calibrated model was evaluated using dendrochronological and LAI data obtained from plots. Main results: Observed and simulated DBH showed a high correlation (R2 > 0.99) between modelled and measured values for both species. In contrast, modelled and observed BAI showed lower correlation (R2 < 0.68). Sensitivity analysis on 3-PG outputs showed that the foliage parameters - maximum litterfall rate, maximum canopy conductance, specific leaf area for mature aged stands, age at which specific leaf area, and age at full canopy cover - were important for DBH and BAI predictions under drought stress. Research highlights: Our overall results indicated that the 3-PG model could predict growth response of pine plantations to climatic stress with desirable accuracy in southern Spain by using readily available soil and climatic data with physiological parameters derived from experiments. (Author)

  14. Temporal Variation of Wood Density and Carbon in Two Elevational Sites of Pinus cooperi in Relation to Climate Response in Northern Mexico

    Science.gov (United States)

    Pompa-García, Marín; Venegas-González, Alejandro

    2016-01-01

    Forest ecosystems play an important role in the global carbon cycle. Therefore, understanding the dynamics of carbon uptake in forest ecosystems is much needed. Pinus cooperi is a widely distributed species in the Sierra Madre Occidental in northern Mexico and future climatic variations could impact these ecosystems. Here, we analyze the variations of trunk carbon in two populations of P. cooperi situated at different elevational gradients, combining dendrochronological techniques and allometry. Carbon sequestration (50% biomass) was estimated from a specific allometric equation for this species based on: (i) variation of intra-annual wood density and (ii) diameter reconstruction. The results show that the population at a higher elevation had greater wood density, basal area, and hence, carbon accumulation. This finding can be explained by an ecological response of trees to adverse weather conditions, which would cause a change in the cellular structure affecting the within-ring wood density profile. The influence of variations in climate on the maximum density of chronologies showed a positive correlation with precipitation and the Multivariate El Niño Southern Oscillation Index during the winter season, and a negative correlation with maximum temperature during the spring season. Monitoring previous conditions to growth is crucial due to the increased vulnerability to extreme climatic variations on higher elevational sites. We concluded that temporal variability of wood density contributes to a better understanding of environmental historical changes and forest carbon dynamics in Northern Mexico, representing a significant improvement over previous studies on carbon sequestration. Assuming a uniform density according to tree age is incorrect, so this method can be used for environmental mitigation strategies, such as for managing P. cooperi, a dominant species of great ecological amplitude and widely used in forest industries. PMID:27272519

  15. [Climate-growth relationships of Picea koraiensis and causes of its recent decline in Xiaoxing' an Mountains, China].

    Science.gov (United States)

    Yao, Qi-chao; Wang, Xiao-chun; Xiao, Xing-wei

    2015-07-01

    Two tree-ring width chronologies of Picea koraiensis at two altitudes in Fenglin National Nature Reserve of Xiaoxing'an Mountains, China were developed by using dendrochronological methods. To identify main limiting factors of P. koraiensis radial growth at the two altitudes, the relationships between the chronologies and local temperature, precipitation, Palmer drought severity index (PDSI), and large-scale climatic factors were investigated. Meanwhile, the reasons of P. koraiensis growth decline in recent years were also explored. Results showed that radial growth of P. koraiensis in Xiaoxing'an Mountains was mainly limited by temperatures, especially by the minimum temperature in growing season, while the limiting effect of precipitation was relatively weak. Climate responses of P. koraiensis growth at the different altitudes showed significant differences. Radial growths of P. koraiensis at the low altitude were positively correlated with precipitation in the current growth season (June-September) and whole year, and negatively correlated with soil temperatures at different depths, especially at 80 cm depth in growing season. Meanwhile, it was signi-ficantly positively correlated with PDSI in growing season. However, the relationships between radial growth of P. koraiensis at the high altitude and precipitation, air and soil temperatures, and PDSI were not significant as that at the low altitude. Growth decline of P. koraiensis in Xiaoxing'an Mountains could be related to the phase changes in Atlantic multidecadal oscillation (AMO) and Pacific decadal oscillation (PDO) and the significant global warming since 1980. The coupling effects of the above changes might result in increased soil evaporation and exacerbated warming and drying phenomena, consequently causing the growth decline of P. koraiensis at the low altitude.

  16. Greening and browning of the Himalaya: Spatial patterns and the role of climatic change and human drivers.

    Science.gov (United States)

    Mishra, Niti B; Mainali, Kumar P

    2017-06-01

    The reliable detection and attribution of changes in vegetation greenness is a prerequisite for the development of strategies for the sustainable management of ecosystems. We conducted a robust trend analysis on remote sensing derived vegetation index time-series matrices to detect significant changes in inter-annual vegetation productivity (greening versus browning) for the entire Himalaya, a biodiverse and ecologically sensitive yet understudied region. The spatial variability in trend was assessed considering elevation, 12 dominant land cover/use types and 10 ecoregions. To assess trend causation, at local scale, we compared multi-temporal imagery, and at regional scale, referenced ecological theories of mountain vegetation dynamics and ancillary literature. Overall, 17.56% of Himalayan vegetation (71,162km 2 ) exhibited significant trend (p3800m), with eastern high Himalaya browning more dominantly than western high Himalaya. Land cover/use based categorization confirmed dominant greening of rainfed and irrigated agricultural areas, though cropped areas in western Himalaya contained higher proportion of greening areas. While rising atmospheric CO 2 concentration and nitrogen deposition are the most likely climatic causes of detected greening, success of sustainable forestry practices (community forestry in Nepal) along with increasing agricultural fertilization and irrigation facilities could be possible human drivers. Comparison of multi-temporal imagery enabled direct attribution of some browning areas to anthropogenic land change (dam, airport and tunnel construction). Our satellite detected browning of high altitude vegetation in eastern Himalaya confirm the findings of recent dendrochronology based studies which possibly resulted from reduced pre-monsoon moisture availability in recent decades. These results have significant implications for environmental management in the context of climate change and ecosystem dynamics in the Himalaya. Copyright © 2017

  17. Paleoclimatology: a survey on ancient climates. Volume 1 - To find, date and interpret indices; Volume 2 - To fit the puzzle pieces one to the other: to understand and model a complex system

    International Nuclear Information System (INIS)

    Duplessy, J.C.; Ramstein, G.; Berger, A.; Joussaume, S.; Guillou, H.; Paterne, M.; Michel, E.; Hatte, C.; Dutay, J.C.; Nomade, S.; Scaillet, S.; Frank, N.; Salle, E.; Laj, C.; Channell, J.E.T.; Kissel, C.; Guibal, F.; Guiot, J.; Parrenin, F.; Masson-Delmotte, V.; Jouzel, J.; Rousseau, D.D.; Genty, D.; Von Grafenstein, U.; Belmecheri, S.; Daux, V.; Williamson, D.; Gasse, F.; Vimeux, F.; Cortijo, E.; Labeyrie, L.; Bopp, L.; Friedlingstein, P.; Chappellaz, J.; Legrand, M.; Delmas, R.; Ritz, C.; Peyaud, V.; Waelbroeck, C.; Colleoni, F.; Fluteau, F.; Kageyama, M.; Paillard, D.; Godderis, Y.; Le Hir, G.; Donnadieu, Y.; Roche, D.M.; Combourieu Nebout, N.; Braconnot, P.; Yiou, P.; Charbit, S.; Dufresne, J.L.; Cattiaux, J.

    2013-11-01

    The first volume of this collective publication gathers contributions on techniques used to reconstruct past climates. The chapters address the climate system operation and history (evolution, mechanisms, the atmosphere, oceans, ground and marine biosphere, cryo-sphere, lithosphere), propose an introduction to geochronology, present and discuss various dating methods (carbon 14, K-Ar and Ar-Ar methods, dating of corals and other geological samples based the disequilibrium between uranium and thorium isotopes, use of magnetic stratigraphy, dendro-chronology, dating of ice archives), discuss how to reconstruct atmosphere physics and circulation, address the use and properties of different interfaces (air-ice with polar ices, air-plants with pollen, air-soil with loessic sequences as markers of atmospheric circulation or reconstruction of paleo-climates with speleothems, air-lake, plant-atmosphere, air-plant, air-water, air-ice in tropical glaciers), and discuss the use of paleo-oceanography data. The second volume gathers contributions in which the authors present the most recent approaches used to reconstruct the operation of the climate system in the past by using present observations and models. The chapters address the biochemistry of the climate system during the last million of years, the relationship between cryo-sphere and sea level, the climate at the scale of geological times, modelling approaches in paleoclimatology, the Precambrian climate, the Phanerozoic climates, the relationship between climate and astronomic cycles, the description and mechanisms of quick climate variability, the Holocene and the anthropogenic perturbation, and the evolution from past climates to future climates

  18. Four centuries of reconstructed hydroclimatic variability for Northwestern Chihuahua, Mexico, based on tree rings

    Directory of Open Access Journals (Sweden)

    José Villanueva Díaz

    2015-03-01

    Full Text Available A Douglas-fir chronology with a length of 409 years (1600-2008 was developed for northwestern Chihuahua in Mesa de las Guacamayas, a “Natural Protected Area” known as an important nesting habitat for the thickbilled parrot (Rhynchopsitta pachyrhyncha an endangered neotropical bird. Increment cores and cross-sections from selected Douglas-fir trees (Pseudotsuga menziesii in a mixed conifer forest were obtained with an increment borer and a chain-saw. Standard dendrochronological techniques were used to process and date each one of the rings to their exact year of formation. The quality of dating of the measured series was analyzed with the COFECHA program, while biological trends not related to climate (age differences, stem-size increases, and disturbances were removed by standardization procedures in the ARSTAN program. Tree ring series of earlywood, latewood and total ring width were developed for the last four centuries. The total ring-width chronology was significantly associated (r>0.40, p=0.000 with nearby chronologies, particularly those located <200 km apart along the western slopes of the Sierra Madre Occidental (SMO observing correlations as high as 0.69 (p<0.001. Association between chronologies decreased for those sites in the state of Durango along the SMO but separated more than 200 km in straight line and also for sites in nearby borderline in the USA side. The similar climatic response among distant chronologies implies the influence of common atmospheric circulatory patterns affecting a large portion of land simultaneously. ENSO is one of the most important factors in determining inter-annual and multiannual hydroclimatic variability in northern Mexico, increasing winter-spring precipitation in its warm phase and causing extreme droughts in its cold phase.

  19. A 481-year chronology of oak earlywood vessels as an age-independent climatic proxy in NW Iberia

    Science.gov (United States)

    Souto-Herrero, Manuel; Rozas, Vicente; García-González, Ignacio

    2017-08-01

    The earlywood vessels of ring-porous trees can be analyzed dendrochronologically and used as a proxy for environmental information. However, most works deal with the analysis of contemporary climate-growth relationships and do not evaluate their long-term variation. We obtained a 481-year chronology of earlywood vessel size of oak (Quercus robur L.) in the northwestern Iberian Peninsula, investigated its behavior through time, and compared it to a chronology of younger trees developed at the same site. We expressed earlywood vessel size as the hydraulically-weighted diameter (DH) and discriminated between vessels in the first row (r1) and the rest of the vessels (nr1); radial increment was assessed from latewood width (LW). Climate-growth relationships were strong and nearly identical for both age classes. Spring temperature positively affected vessel size, but only for the first row, probably mediating the onset of cambial activity. The chronology of old trees showed an almost flat age trend, except for the first decades, and series were not affected by stand dynamics. In contrast, LW had a weak response to climate, probably because of the high impact of abrupt growth changes. There was a high negative correlation between DH and the winter North Atlantic Oscillation Index (NAO), which was unstable during the 20th century. To our knowledge, this is the longest chronology of earlywood vessel size obtained to date, and offers promising results, as this proxy is shown to be independent of age and forest disturbances, and was strongly correlated to climate across long time spans.

  20. Isotope signals and anatomical features in tree rings suggest a role for hydraulic strategies in diffuse drought-induced die-back of Pinus nigra.

    Science.gov (United States)

    Petrucco, Laura; Nardini, Andrea; von Arx, Georg; Saurer, Matthias; Cherubini, Paolo

    2017-04-01

    The 2003 and 2012 summer seasons were among the warmest and driest of the last 200 years over southeastern Europe, and in particular in the Karst region (northeastern Italy). Starting from winter-spring 2013, several black pines (Pinus nigra J.F. Arnold) suffered crown die-back. Declining trees occurred nearby individuals with no signs of die-back, raising hypotheses about the occurrence of individual-specific hydraulic strategies underlying different responses to extreme drought. We investigated possible processes driving black pine decline by dendrochronological and wood anatomical measurements, coupled with analysis of tree-ring carbon (δ13C) and oxygen (δ18O) isotopic composition in healthy trees (H) and trees suffering die-back (D). Die-back trees showed higher growth rates than H trees at the beginning of the last century, but suffered important growth reduction following the dry summers in 2003 and 2012. After the 2012 drought, D trees produced tracheids with larger diameter and greater vulnerability to implosion than H ones. Healthy trees had significantly higher wood δ13C than D trees, reflecting higher water-use efficiency for the surviving trees, i.e., less water transpired per unit carbon gain, which could be related to lower stomatal conductance and a more conservative use of water. Relatively high δ18O for D trees indicates that they were strongly dependent on shallow water sources, or that they sustained higher transpiration rates than H trees. Our results suggest that H trees adopted a more conservative water-use strategy under drought stress compared with D trees. We speculate that this diversity might have a genotypic basis, but other possible explanations, like different rooting depth, cannot be ruled out. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Conifer Decline and Mortality in Siberia

    Science.gov (United States)

    Kharuk, V.; Im, S.; Ranson, K.

    2015-12-01

    "Dark needle conifer" (DNC: Abies sibirica, Pinus sibirica and Picea obovata) decline and mortality increase were documented in Russia during recent decades. Here we analyzed causes and scale of Siberian pine and fir mortality in Altai-Sayan and Baikal Lake Regions and West Siberian Plane based on in situdata and remote sensing (QuickBird, Landsat, GRACE). Geographically, mortality began on the margins of the DNC range (i.e., within the forest-steppe and conifer-broadleaf ecotones) and on terrain features with maximal water stress risk (narrow-shaped hilltops, convex steep south facing slopes, shallow well-drained soils). Within ridges, mortality occurred mainly along mountain passes, where stands faced drying winds. Regularly mortality was observed to decrease with elevation increase with the exception of Baikal Lake Mountains, where it was minimal near the lake shore and increased with elevation (up to about 1000 m a.s.l.). Siberian pine and fir mortality followed a drying trend with consecutive droughts since the 1980s. Dendrochronology analysis showed that mortality was correlated with vapor pressure deficit increase, drought index, soil moisture decrease and occurrence of late frosts. In Baikal region Siberian pine mortality correlated with Baikal watershed meteorological variables. An impact of previous year climate conditions on the current growth was found (r2 = 0.6). Thus, water-stressed trees became sensitive to bark beetles and fungi impact (including Polygraphus proximus and Heterobasidion annosum). At present, an increase in mortality is observed within the majority of DNC range. Results obtained also showed a primary role of water stress in that phenomenon with a secondary role of bark beetles and fungi attacks. In future climate with increased drought severity and frequency Siberian pine and fir will partly disappear from its current range, and will be substituted by drought-tolerant species (e.g., Pinus silvestris, Larix sibirica).

  2. Impacts of more frequent droughts on a relict low-altitude Pinus uncinata stand in the French Alps

    Directory of Open Access Journals (Sweden)

    Christophe eCorona

    2015-01-01

    Full Text Available Cold microclimatic conditions provide exceptional microhabitats to Pinus uncinata stands occurring at abnormally low altitudes in seven paleorefugia of the northern French Alps. Here, P. uncinata is located at the lower bounds of its ecological limits and therefore expected to provide a sensitive indicator of climate change processes. We used dendrochronological analysis to study the growth patterns of closely spaced chronologies across an elevational transect and compare a relict low-altitude to a P. uncinata stand located at the alpine treeline. Two detrending procedures are used to reveal high and low-frequency wavelengths embedded in annually resolved ring-width series. Growth response of P. uncinata to instrumental temperature and precipitation data is investigated by means of moving response function analyses. Results show an increase in the sensitivity of tree-ring widths to drought during previous summer in both stands. At the treeline stand, an increasing correlation with fall temperature is observed whereby low-frequency variability of fall temperature and radial tree growth increased in two synchronous steps around ~1930 and from ~1980–present. At the low-altitude stand, P. uncinata appears more drought sensitive and exhibits a sharp growth decline since the mid-1980s, coinciding with increasing summer temperatures. Growth divergence between the two stands can be observed since the mid-1980s. We argue that the positive growth trend at the high-altitude stand is due to increasing fall temperatures which would favor the formation of metabolic reserves in conjunction with atmospheric CO2 enrichment that in turn would facilitate improved water use efficiency. At the relict low-altitude stand, in contrast, it seems that improved water use efficiency cannot compensate for the increase in summer temperatures.

  3. Siberian Pine Decline and Mortality in Southern Siberian Mountains

    Science.gov (United States)

    Kharuk, V. I.; Im, S. T.; Oskorbin, P. A.; Petrov, I. A.; Ranson, K. J.

    2013-01-01

    The causes and resulting spatial patterns of Siberian pine mortality in eastern Kuznetzky Alatau Mountains, Siberia were analyzed based on satellite (Landsat, MODIS) and dendrochronology data. Climate variables studied included temperature, precipitation and Standardized Precipitation-Evapotranspiration Index (SPEI) drought index. Landsat data analysis showed that stand mortality was first detected in the year 2006 at an elevation of 650 m, and extended up to 900 m by the year 2012. Mortality was accompanied by a decrease in MODIS derived vegetation index (EVI).. The area of dead stands and the upper mortality line were correlated with increased drought. The uphill margin of mortality was limited by elevational precipitation gradients. Dead stands (i.e., >75% tree mortality) were located mainly on southern slopes. With respect to slope, mortality was observed within a 7 deg - 20 deg range with greatest mortality occurring on convex terrain. Tree radial incrementmeasurements correlate and were synchronous with SPEI (r sq = 0.37, r(sub s) = 80). Increasing synchrony between tree ring growth and SPEI indicates that drought has reduced the ecological niche of Siberian pine. The results also showed the primary role of drought stress on Siberian pine mortality. A secondary role may be played by bark beetles and root fungi attacks. The observed Siberian pine mortality is part of a broader phenomenon of "dark needle conifers" (DNC, i.e., Siberian pine, fir and spruce) decline and mortality in European Russia, Siberia, and the Russian Far East. All locations of DNC decline coincided with areas of observed drought increase. The results obtained are one of the first observations of drought-induced decline and mortality of DNC at the southern border of boreal forests. Meanwhile if model projections of increased aridity are correct DNC, within the southern part of its range may be replaced by drought-resistant Pinus silvestris and Larix sibirica.

  4. Climate impact on the tree growth, vigor and productivity in Siberia

    Science.gov (United States)

    Kharuk, V.; Im, S.; Petrov, I.; Dvinskaya, M.

    2017-12-01

    Changing climate has an impact on the Siberian taiga forests. We analyzed GPP and NPP trends, growth index, and stands mortality within the Central Siberia (48°- 75°N/80°-115°E). Considered forests included larch-dominant (Larix sibirica, L. dahurica) and "dark needle conifer" (DNC: Abies sibirica, Pinus sibirica, Picea obovata) stands. GPP and NPP trends calculated based on the Terra/MODIS products. Growth index calculations based on dendrochronology data. Water stress analysis based on the gravimetric and microwave satellite data and MERRA-2 database. Analyzed variables included precipitation, air temperature, VPD, drought index SPEI, and root zone wetness. We found positive GPP trends within majority (>90%) of larch-dominant and DNC ranges, whereas NPP trends are positive on the +10C°) temperatures and vegetation period length. During recent years larch experience water stress in the beginning of vegetation period. Tree decline and mortality observed within DNC stands, and that phenomenon regularly coincided with zones of negative NPP trends. Mortality correlated with VPD, SPEI, and root zone moisture content. Bark beetles (including aggressive species Polygraphus proximus, similar to Dendroctonus ponderosae in American forests) attacked water-stressed trees. Geographically, mortality began on the margins of the DNC range (e.g., within the forest-steppe ecotone) and on terrain features with maximal water stress risk (narrow-shaped hilltops, convex steep south facing slopes, shallow well-drained soils). Currently, Siberian pine and fir decline observed within southern range of these species. In addition, air temperature and aridity increase promotes Siberian silkmoth (Dendrolimus sibiricus) outbreak that occurred about one degree northward of formerly range. Observing and predicting aridity increase will lead to the replacement of Siberian pine and fir within southern range of these species with more tolerant species (e.g., Pinus sylvestris, Larix spp.).

  5. Growth decline assessment in Pinus sylvestris L. and Pinus nigra Arnold. forest by using 3-PG model.

    Directory of Open Access Journals (Sweden)

    Rafael M. Navarro-Cerrillo

    2016-12-01

    Full Text Available Aim of the study: We assessed the ability of the 3-PG process-based model to accurately predict growth of Pinus sylvestris and P. nigra plantations across a range of sites, showing declining growth trends, in southern Spain. Area of study: The study area is located in “Sierra de Los Filabres” (Almería. Material and methods: The model was modified in fifteen parameters to predict diameter (DBH, cm, basal area increment (BAI, cm2 yr-1 and leaf area index (LAI, m2 m-2 in healthy trees and trees showing declining growth. We assumed that a set of specific physiological parameters (stem partitioning ratio-pFS20, maximum litterfall rate-γFx, maximum canopy conductance-gCx, specific leaf area for mature aged stands-σ1, age at which specific leaf area = ½ (σ0 + σ1, age at full canopy cover-tc, and canopy boundary layer conductance-gB included in 3-PG would be suitable for predicting growth decline related to climate conditions. The calibrated model was evaluated using dendrochronological and LAI data obtained from plots. Main results: Observed and simulated DBH showed a high correlation (R2 > 0.99 between modelled and measured values for both species. In contrast, modelled and observed BAI showed lower correlation (R2 < 0.68. Sensitivity analysis on 3-PG outputs showed that the foliage parameters - maximum litterfall rate, maximum canopy conductance, specific leaf area for mature aged stands, age at which specific leaf area, and age at full canopy cover - were important for DBH and BAI predictions under drought stress. Research highlights: Our overall results indicated that the 3-PG model could predict growth response of pine plantations to climatic stress with desirable accuracy in southern Spain by using readily available soil and climatic data with physiological parameters derived from experiments. Keywords: Hybrid process model; forest management models; growth prediction; Pinus spp, Parameterization; forest decline.

  6. Powdery Mildew Decreases the Radial Growth of Oak Trees with Cumulative and Delayed Effects over Years.

    Directory of Open Access Journals (Sweden)

    Didier Bert

    Full Text Available Quercus robur and Q. petraea are major European forest tree species. They have been affected by powdery mildew caused by Erysiphe alphitoides for more than a century. This fungus is a biotrophic foliar pathogen that diverts photosynthetate from the plant for its own nutrition. We used a dendrochronological approach to investigate the effects of different levels of infection severity on the radial growth of young oak trees. Oak infection was monitored at individual tree level, at two sites in southwestern France, over a five-year period (2001-2005. Mean infection severity was almost 75% (infected leaf area at the end of the 2001 growing season, at both sites, but only about 40% in 2002, and 8%, 5% and 2% in 2003, 2004 and 2005, respectively. Infection levels varied considerably between trees and were positively related between 2001 and 2002. Increment cores were taken from each tree to assess annual ring widths and increases in basal area. Annual radial growth was standardised to take the effect of tree size into account. Annual standardised radial growth was significantly and negatively correlated with infection severity in the same year, for both 2001 and 2002, and at both sites. The decrease in growth reached 70-90% for highly infected trees. The earlywood width was poorly correlated with infection severity, but the proportion of latewood in tree rings was lower in highly infected trees (60% than in less heavily infected trees (85%. Infection in 2001 and 2002 was found to have a cumulative effect on radial growth in these years, together with a delayed effect detectable in 2003. Thus, even non-lethal pathogens like powdery mildew can have a significant impact on tree functioning. This impact should be taken into account in growth and yield models, to improve predictions of forest net primary production.

  7. New tree-ring evidence for the Late Glacial period from the northern pre-Alps in eastern Switzerland

    Science.gov (United States)

    Reinig, Frederick; Nievergelt, Daniel; Esper, Jan; Friedrich, Michael; Helle, Gerhard; Hellmann, Lena; Kromer, Bernd; Morganti, Sandro; Pauly, Maren; Sookdeo, Adam; Tegel, Willy; Treydte, Kerstin; Verstege, Anne; Wacker, Lukas; Büntgen, Ulf

    2018-04-01

    The rate and magnitude of temperature variability at the transition from the Last Glacial Maximum into the early Holocene represents a natural analog to current and predicted climate change. A limited number of high-resolution proxy archives, however, challenges our understanding of environmental conditions during this period. Here, we present combined dendrochronological and radiocarbon evidence from 253 newly discovered subfossil pine stumps from Zurich, Switzerland. The individual trees reveal ages of 41-506 years and were growing between the Allerød and Preboreal (∼13‧900-11‧300 cal BP). Together with previously collected pines from this region, this world's best preserved Late Glacial forest substantially improves the earliest part of the absolutely dated European tree-ring width chronology between 11‧300 and 11‧900 cal BP. Radiocarbon measurements from 65 Zurich pines between ∼12‧320 and 13‧950 cal BP provide a perspective to prolong the continuous European tree-ring record by another ∼2000 years into the Late Glacial era. These data will also be relevant for pinpointing the Laacher See volcanic eruption (∼12‧900 cal BP) and two major Alpine earthquakes (∼13‧770 and ∼11‧600 cal BP). In summary, this study emphasizes the importance of dating precision and multi-proxy comparison to disentangle environmental signals from methodological noise, particularly during periods of high climate variability but low data availability, such as the Younger Dryas cold spell (∼11‧700 and 12‧900 cal BP).

  8. Recent trends in the intrinsic water-use efficiency of ringless rainforest trees in Borneo.

    Science.gov (United States)

    Loader, N J; Walsh, R P D; Robertson, I; Bidin, K; Ong, R C; Reynolds, G; McCarroll, D; Gagen, M; Young, G H F

    2011-11-27

    Stable carbon isotope (δ(13)C) series were developed from analysis of sequential radial wood increments from AD 1850 to AD 2009 for four mature primary rainforest trees from the Danum and Imbak areas of Sabah, Malaysia. The aseasonal equatorial climate meant that conventional dendrochronology was not possible as the tree species investigated do not exhibit clear annual rings or dateable growth bands. Chronology was established using radiocarbon dating to model age-growth relationships and date the carbon isotopic series from which the intrinsic water-use efficiency (IWUE) was calculated. The two Eusideroxylon zwageri trees from Imbak yielded ages of their pith/central wood (±1 sigma) of 670 ± 40 and 759 ± 40 years old; the less dense Shorea johorensis and Shorea superba trees at Danum yielded ages of 240 ± 40 and 330 ± 40 years, respectively. All trees studied exhibit an increase in the IWUE since AD 1960. This reflects, in part, a response of the forest to increasing atmospheric carbon dioxide concentration. Unlike studies of some northern European trees, no clear plateau in this response was observed. A change in the IWUE implies an associated modification of the local carbon and/or hydrological cycles. To resolve these uncertainties, a shift in emphasis away from high-resolution studies towards long, well-replicated time series is proposed to develop the environmental data essential for model evaluation. Identification of old (greater than 700 years) ringless trees demonstrates their potential in assessing the impacts of climatic and atmospheric change. It also shows the scientific and applied value of a conservation policy that ensures the survival of primary forest containing particularly old trees (as in Imbak Canyon and Danum).

  9. Contrasting growth forecasts across the geographical range of Scots pine due to altitudinal and latitudinal differences in climatic sensitivity.

    Science.gov (United States)

    Matías, Luis; Linares, Juan C; Sánchez-Miranda, Ángela; Jump, Alistair S

    2017-10-01

    Ongoing changes in global climate are altering ecological conditions for many species. The consequences of such changes are typically most evident at the edge of a species' geographical distribution, where differences in growth or population dynamics may result in range expansions or contractions. Understanding population responses to different climatic drivers along wide latitudinal and altitudinal gradients is necessary in order to gain a better understanding of plant responses to ongoing increases in global temperature and drought severity. We selected Scots pine (Pinus sylvestris L.) as a model species to explore growth responses to climatic variability (seasonal temperature and precipitation) over the last century through dendrochronological methods. We developed linear models based on age, climate and previous growth to forecast growth trends up to year 2100 using climatic predictions. Populations were located at the treeline across a latitudinal gradient covering the northern, central and southernmost populations and across an altitudinal gradient at the southern edge of the distribution (treeline, medium and lower elevations). Radial growth was maximal at medium altitude and treeline of the southernmost populations. Temperature was the main factor controlling growth variability along the gradients, although the timing and strength of climatic variables affecting growth shifted with latitude and altitude. Predictive models forecast a general increase in Scots pine growth at treeline across the latitudinal distribution, with southern populations increasing growth up to year 2050, when it stabilizes. The highest responsiveness appeared at central latitude, and moderate growth increase is projected at the northern limit. Contrastingly, the model forecasted growth declines at lowland-southern populations, suggesting an upslope range displacement over the coming decades. Our results give insight into the geographical responses of tree species to climate change

  10. Are low altitude alpine tundra ecosystems under threat? A case study from the Parc National de la Gaspésie, Québec

    International Nuclear Information System (INIS)

    Dumais, Catherine; Ropars, Pascale; Denis, Marie-Pier; Dufour-Tremblay, Geneviève; Boudreau, Stéphane

    2014-01-01

    According to the 2007 IPCC report, the alpine tundra ecosystems found on low mountains of the northern hemisphere are amongst the most threatened by climate change. A treeline advance or a significant erect shrub expansion could result in increased competition for the arctic-alpine species usually found on mountaintops and eventually lead to their local extinction. The objectives of our study were to identify recent changes in the cover and growth of erect woody vegetation in the alpine tundra of Mont de la Passe, in the Parc National de la Gaspésie (Québec, Canada). The comparison of two orthorectified aerial photos revealed no significant shift of the treeline between 1975 and 2004. During the same period however, shrub species cover increased from 20.2% to 30.4% in the lower alpine zone. Dendrochronological analyses conducted on Betula glandulosa Michx. sampled at three different positions along an altitudinal gradient (low, intermediate and high alpine zone) revealed that the climatic determinants of B. glandulosa radial growth become more complex with increasing altitude. In the lower alpine zone, B. glandulosa radial growth is only significantly associated positively to July temperature. In the intermediate alpine zone, radial growth is associated positively to July temperature but negatively to March temperature. In the high alpine zone, radial growth is positively associated to January, July and August temperature but negatively to March temperature. The positive association between summer temperatures and radial growth suggests that B. glandulosa could potentially benefit from warmer temperatures, a phenomenon that could lead to an increase in its cover over the next few decades. Although alpine tundra vegetation is not threatened in the short-term in the Parc National de la Gaspésie, erect shrub cover, especially B. glandulosa, could likely increase in the near future, threatening the local arctic-alpine flora. (letter)

  11. Chemo-ecological studies on plant indicators for low level air pollution

    International Nuclear Information System (INIS)

    Katoh, Terutaka; Kasuya, Minoru; Kagamimori, Sadanobu; Kozuka, Hiroshi; Kawano, Shoichi.

    1991-01-01

    The effects of low level air pollution on Japanese Cedar (Cryptomeria japonica) have been studied in the surrounding area of two thermoelectric power stations newly constructed in a rural area, Fukui Prefecture, on the Japan Sea side of central Honshu, Japan. The degree of visual injury in Japanese Cedar, scored with six different categories, was examined in 1974 and 1977 respectively, covering the entire study area. A more complete monitoring has been conducted at eight permanent sites in Awara-cho since 1974. A dendrochronological study was also carried out to evaluate the effects of air pollution on the increment growth of Japanese Cedars. There were clear correlations between the distance from the power station and tree decline. Severe damage was observed, in general, within a 7 km radius from the power station. The localized injury of Japanese Cedar, along the flood plain of the two rivers, was also demonstrated. A rapid increase of injury was noted until through the late 1970's. The growth inhibition, during this period, was also revealed by tree ring analysis. Some recovery of tree vigor and increment growth was observed after the introduction of pollution control systems at the power station. Consistent relationships were demonstrated between the index of increment growth, i.e., standardized ring index, and the levels of SO 2 and NO 2 . Scarcely any correlation was observed between pH of rain water and the standardized ring index. Decreased levels of foliar tannin were observed in the Japanese Cedars growing in the polluted areas. The inhibition of the shikimate pathway, by air pollution, was suggested by biochemical studies. Increased predation damage was observed in the foliage of Japanese Cedars with low tannin levels. The predisposed effects of air pollution were discussed with special reference to the inhibition of the shikimate pathway. (author)

  12. Picture This: The Art of Using Museum and Science Collaborations to Teach about Climate Change

    Science.gov (United States)

    Fiondella, F.; Fowler, R.; Davi, N. K.; Gawthrop, E.

    2015-12-01

    Connecting scientists and their research to photography galleries and museums is an effective way to promote climate literacy among a new, diverse audience. This approach requires creativity and a willingness to reach out to and work with staff unfamiliar with scientific institutions, but can result in broad exposure and understanding of the impacts of climate change. In this presentation we highlight the successful science-art collaboration among the International Center of Photography, Lamont-Doherty Earth Observatory and the International Research Institute for Climate and Society. The collaboration revolved around ICP's 2014-2015 exhibition of renowned photographer Sebastiao Salgado's Genesis, an eight-year worldwide survey of wildlife, landscapes, seascapes and indigenous peoples. Salgado's photographs acted as a springboard for a unique public education program based at ICP and aimed at raising awareness of the urgent issue of climate change. Over the course of six months, Lamont and IRI scientists with expertise in climatology, dendrochronology, seismology and glaciology led gallery tours for the public, making links between their research and the places and people of Salgado's photography. Lamont and IRI staff also gave talks throughout the exhibition period on topics ranging from climate change adaptation to the use of photography to help the public visualize the impacts of Earth's changing climate. The research institutions also took over ICP's Instagram feed for a week, showcasing the climate-related field work of more than a dozen scientists. All three institutions, the participating scientists and program attendees deemed the collaboration a success. We'll explain what made this collaboration successful and provide tips on how scientists and their institutes can form similar collaborations with museums and other arts-based organizations.

  13. Laser ablation-combustion-GC-IRMS--a new method for online analysis of intra-annual variation of delta13C in tree rings.

    Science.gov (United States)

    Schulze, Brigit; Wirth, Christian; Linke, Petra; Brand, Willi A; Kuhlmann, Iris; Horna, Viviana; Schulze, Ernst-Detlef

    2004-11-01

    We present a new, rapid method for high-resolution online determination of delta13C in tree rings, combining laser ablation (LA), combustion (C), gas chromatography (GC) and isotope ratio mass spectrometry (IRMS) (LA-C-GC-IRMS). Sample material was extracted every 6 min with a UV-laser from a tree core, leaving 40-microm-wide holes. Ablated wood dust was combusted to CO2 at 700 degrees C, separated from other gases on a GC column and injected into an isotope ratio mass spectrometer after removal of water vapor. The measurements were calibrated against an internal and an external standard. The tree core remained intact and could be used for subsequent dendrochronological and dendrochemical analyses. Cores from two Scots pine trees (Pinus sylvestris spp. sibirica Lebed.) from central Siberia were sampled. Inter- and intra-annual patterns of delta13C in whole-wood and lignin-extracted cores were indistinguishable apart from a constant offset, suggesting that lignin extraction is unnecessary for our method. Comparison with the conventional method (microtome slicing, elemental analysis and IRMS) indicated high accuracy of the LA-C-GC-IRMS measurements. Patterns of delta13C along three parallel ablation lines on the same core showed high congruence. A conservative estimate of the precision was +/- 0.24 per thousand. Isotopic patterns of the two Scots pine trees were broadly similar, indicating a signal related to the forest stand's climate history. The maximum variation in delta13C over 22 years was about 5 per thousand, ranging from -27 to -22.3 per thousand. The most obvious pattern was a sharp decline in delta13C during latewood formation and a rapid increase with spring early growth. We conclude that the LA-C-GC-IRMS method will be useful in elucidating short-term climate effects on the delta13C signal in tree rings.

  14. Missing Rings, Synchronous Growth, and Ecological Disturbance in a 36-Year Pitch Pine (Pinus rigida Provenance Study.

    Directory of Open Access Journals (Sweden)

    Caroline Leland

    Full Text Available Provenance studies are an increasingly important analog for understanding how trees adapted to particular climatic conditions might respond to climate change. Dendrochronological analysis can illuminate differences among trees from different seed sources in terms of absolute annual growth and sensitivity to external growth factors. We analyzed annual radial growth of 567 36-year-old pitch pine (Pinus rigida Mill. trees from 27 seed sources to evaluate their performance in a New Jersey Pine Barrens provenance experiment. Unexpectedly, missing rings were prevalent in most trees, and some years-1992, 1999, and 2006-had a particularly high frequency of missing rings across the plantation. Trees from local seed sources (<55 km away from the plantation had a significantly smaller percentage of missing rings from 1980-2009 (mean: 5.0%, relative to northernmost and southernmost sources (mean: 9.3% and 7.9%, respectively. Some years with a high frequency of missing rings coincide with outbreaks of defoliating insects or dry growing season conditions. The propensity for missing rings synchronized annual variations in growth across all trees and might have complicated the detection of potential differences in interannual variability among seed sources. Average ring width was significantly larger in seed sources from both the southernmost and warmest origins compared to the northernmost and coldest seed sources in most years. Local seed sources had the highest average radial growth. Adaptation to local environmental conditions and disturbances might have influenced the higher growth rate found in local seed sources. These findings underscore the need to understand the integrative impact of multiple environmental drivers, such as disturbance agents and climate change, on tree growth, forest dynamics, and the carbon cycle.

  15. Seasonality of bottom water temperature in the northern North Sea reconstructed from the oxygen isotope composition of the bivalve Arctica islandica

    Science.gov (United States)

    Trofimova, Tamara; Andersson, Carin; Bonitz, Fabian

    2017-04-01

    The seasonality of temperature changes is an important characteristic of climate. However, observational data for the ocean are only available for the last 150 year from a limited number of locations. Prior to 18th century information is only available from proxy reconstructions. The vast majority of such reconstructions depend on land-based archives, primarily from dendrochronology. Established marine proxy records for the ocean, especially at high latitudes, are both sparsely distributed and poorly resolved in time. Therefore, the identification and development of proxies for studying key ocean processes at sub-annual resolution that can extend the marine instrumental record is a clear priority in marine climate science. In this study, we have developed a record of early Holocene seasonal variability of bottom water temperature from the Viking Bank in the northern most North Sea. This area is of a particular interest since the hydrography is controlled by the inflow of Atlantic water. The reconstruction is based on the oxygen isotope composition of the growth increments in two sub-fossil shells of Arctica islandica (Bivalvia), dated to 9600-9335 cal. yr BP. By combining radiocarbon dating and sclerochronological techniques a floating chronology spanning over 200 years was constructed. Using the chronology as an age model, oxygen isotope measurements from 2 shells were combined into a 22-years long record. The results from this oxygen isotope record are compared with stable oxygen isotope profiles from modern shells to estimate changes in the mean state and seasonality between present and early Holocene. Shell-derived oxygen isotope values together with ice-volume corrected oxygen isotope values for the seawater were used to calculate bottom-water temperatures on a sub-annual time-scale. Preliminary results of the reconstructed early Holocene bottom water temperature indicate higher seasonality and lower minimum temperature compared to the present.

  16. Nonlinearities, scale-dependence, and individualism of boreal forest trees to climate forcing

    Science.gov (United States)

    Wolken, J. M.; Mann, D. H.; Grant, T. A., III; Lloyd, A. H.; Hollingsworth, T. N.

    2013-12-01

    Our understanding of the climate-growth relationships of trees are complicated by the nonlinearity and variability of these responses through space and time. Furthermore, trees growing at the same site may exhibit opposing growth responses to climate, a phenomenon termed growth divergence. To date the majority of dendrochronological studies in Interior Alaska have involved white spruce growing at treeline, even though black spruce is the most abundant tree species. Although changing climate-growth relationships have been observed in black spruce, there is little known about the multivariate responses of individual trees to temperature and precipitation and whether or not black spruce exhibits growth divergences similar to those documented for white spruce. To evaluate the occurrence of growth divergences in black spruce, we collected cores from trees growing on a steep, north-facing toposequence having a gradient in environmental parameters. Our overall goal was to assess how the climate-growth relationships of black spruce change over space and time. Specifically, we evaluated how topography influences the climate-growth relationships of black spruce and if the growth responses to climate are homogeneous. At the site-level most trees responded negatively to temperature and positively to precipitation, while at the tree-level black spruce exhibited heterogenous growth responses to climate that varied in both space (i.e., between sites) and time (i.e., seasonally and annually). There was a dominant response-type at each site, but there was also considerable variability in the proportion of trees exhibiting each response-type combination. Even in a climatically extreme setting like Alaska's boreal forest, tree responses to climate variability are spatially and temporally complex, as well as highly nonlinear.

  17. Differential growth responses to water balance of coexisting deciduous tree species are linked to wood density in a Bolivian tropical dry forest.

    Directory of Open Access Journals (Sweden)

    Hooz A Mendivelso

    Full Text Available A seasonal period of water deficit characterizes tropical dry forests (TDFs. There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability.

  18. Thinning increases climatic resilience of red pine

    Science.gov (United States)

    Magruder, Matthew; Chhin, Sophan; Palik, Brian; Bradford, John B.

    2013-01-01

    Forest management techniques such as intermediate stand-tending practices (e.g., thinning) can promote climatic resiliency in forest stands by moderating tree competition. Residual trees gain increased access to environmental resources (i.e., soil moisture, light), which in turn has the potential to buffer trees from stressful climatic conditions. The influences of climate (temperature and precipitation) and forest management (thinning method and intensity) on the productivity of red pine (Pinus resinosa Ait.) in Michigan were examined to assess whether repeated thinning treatments were able to increase climatic resiliency (i.e., maintaining productivity and reduced sensitivity to climatic stress). The cumulative productivity of each thinning treatment was determined, and it was found that thinning from below to a residual basal area of 14 m2·ha−1 produced the largest average tree size but also the second lowest overall biomass per acre. On the other hand, the uncut control and the thinning from above to a residual basal area of 28 m2·ha−1 produced the smallest average tree size but also the greatest overall biomass per acre. Dendrochronological methods were used to quantify sensitivity of annual radial growth to monthly and seasonal climatic factors for each thinning treatment type. Climatic sensitivity was influenced by thinning method (i.e., thinning from below decreased sensitivity to climatic stress more than thinning from above) and by thinning intensity (i.e., more intense thinning led to a lower climatic sensitivity). Overall, thinning from below to a residual basal area of 21 m2·ha−1 represented a potentially beneficial compromise to maximize tree size, biomass per acre, and reduced sensitivity to climatic stress, and, thus, the highest level of climatic resilience.

  19. Temporal Variation of Wood Density and Carbon in Two Elevational Sites of Pinus cooperi in Relation to Climate Response in Northern Mexico.

    Directory of Open Access Journals (Sweden)

    Marín Pompa-García

    Full Text Available Forest ecosystems play an important role in the global carbon cycle. Therefore, understanding the dynamics of carbon uptake in forest ecosystems is much needed. Pinus cooperi is a widely distributed species in the Sierra Madre Occidental in northern Mexico and future climatic variations could impact these ecosystems. Here, we analyze the variations of trunk carbon in two populations of P. cooperi situated at different elevational gradients, combining dendrochronological techniques and allometry. Carbon sequestration (50% biomass was estimated from a specific allometric equation for this species based on: (i variation of intra-annual wood density and (ii diameter reconstruction. The results show that the population at a higher elevation had greater wood density, basal area, and hence, carbon accumulation. This finding can be explained by an ecological response of trees to adverse weather conditions, which would cause a change in the cellular structure affecting the within-ring wood density profile. The influence of variations in climate on the maximum density of chronologies showed a positive correlation with precipitation and the Multivariate El Niño Southern Oscillation Index during the winter season, and a negative correlation with maximum temperature during the spring season. Monitoring previous conditions to growth is crucial due to the increased vulnerability to extreme climatic variations on higher elevational sites. We concluded that temporal variability of wood density contributes to a better understanding of environmental historical changes and forest carbon dynamics in Northern Mexico, representing a significant improvement over previous studies on carbon sequestration. Assuming a uniform density according to tree age is incorrect, so this method can be used for environmental mitigation strategies, such as for managing P. cooperi, a dominant species of great ecological amplitude and widely used in forest industries.

  20. Spatiotemporal Dynamics of Fire in Whitebark Pine Stands on two Mountains in the Lolo National Forest, Montana, USA.

    Science.gov (United States)

    Larson, E. R.; Grissino-Mayer, H. D.

    2004-12-01

    Whitebark pine (Pinus albicaulis) is a long-lived tree species that exists throughout high elevation and treeline forest communities of western North America. It is the foundation of a diminishing ecosystem that supports Clark's nutcrackers (Nucifraga columbiana), red squirrels (Tamiasciurus hudsonicus), grizzly bears (Ursus arctos), and black bears (U. americana). Several factors are directly linked to the decline of the whitebark pine ecosystem: mortality from recent and widespread mountain pine beetle (Dendroctonus ponderosae) outbreaks, infestation by the invasive white pine blister rust (Cronartium ribicola, an exotic fungal canker that weakens and eventually kills white pines), and fire suppression that may have altered the historic fire regime and enabled fire-intolerant tree species to encroach upon whitebark pine stands. The synergistic effects of these factors have led to a dramatic decline in whitebark pine communities throughout its native range, and in response land managers and conservationists have called for research to better understand the ecological dynamics of this little studied ecosystem. My research uses dendrochronology to investigate the fire history of whitebark pine stands on three mountains in the Lolo National Forest, Montana, via fire-scar and age structure analyses. I present here the results from the fire-scar analyses from Morrell Mountain where I obtained 40 cross sections from dead and down whitebark pines. Individual tree mean fire return intervals (MFRI) range from 33 to 119 years, with a stand MFRI of 49 years that includes fire scars dating to the 16th century. Fire events scarred multiple trees in AD 1754, 1796, and 1843, indicating a mixed-severity fire regime. The majority of the samples recorded a frost event in AD 1601, perhaps evidence of the AD 1600 eruption of Mt. Huaynapatina in the Peruvian Andes. My research not only provides an historical framework for land managers, but also provides an opportunity to examine long

  1. Forward modeling of tree-ring data: a case study with a global network

    Science.gov (United States)

    Breitenmoser, P. D.; Frank, D.; Brönnimann, S.

    2012-04-01

    Information derived from tree-rings is one of the most powerful tools presently available for studying past climatic variability as well as identifying fundamental relationships between tree-growth and climate. Climate reconstructions are typically performed by extending linear relationships, established during the overlapping period of instrumental and climate proxy archives into the past. Such analyses, however, are limited by methodological assumptions, including stationarity and linearity of the climate-proxy relationship. We investigate climate and tree-ring data using the Vaganov-Shashkin-Lite (VS-Lite) forward model of tree-ring width formation to examine the relations among actual tree growth and climate (as inferred from the simulated chronologies) to reconstruct past climate variability. The VS-lite model has been shown to produce skill comparable to that achieved using classical dendrochronological statistical modeling techniques when applied on simulations of a network of North American tree-ring chronologies. Although the detailed mechanistic processes such as photosynthesis, storage, or cell processes are not modeled directly, the net effect of the dominating nonlinear climatic controls on tree-growth are implemented into the model by the principle of limiting factors and threshold growth response functions. The VS-lite model requires as inputs only latitude, monthly mean temperature and monthly accumulated precipitation. Hence, this simple, process-based model enables ring-width simulation at any location where monthly climate records exist. In this study, we analyse the growth response of simulated tree-rings to monthly climate conditions obtained from the 20th century reanalysis project back to 1871. These simulated tree-ring chronologies are compared to the climate-driven variability in worldwide observed tree-ring chronologies from the International Tree Ring Database. Results point toward the suitability of the relationship among actual tree

  2. Sensitivity of ring growth and carbon allocation to climatic variation vary within ponderosa pine trees.

    Science.gov (United States)

    Kerhoulas, Lucy P; Kane, Jeffrey M

    2012-01-01

    Most dendrochronological studies focus on cores sampled from standard positions (main stem, breast height), yet vertical gradients in hydraulic constraints and priorities for carbon allocation may contribute to different growth sensitivities with position. Using cores taken from five positions (coarse roots, breast height, base of live crown, mid-crown branch and treetop), we investigated how radial growth sensitivity to climate over the period of 1895-2008 varies by position within 36 large ponderosa pines (Pinus ponderosa Dougl.) in northern Arizona. The climate parameters investigated were Palmer Drought Severity Index, water year and monsoon precipitation, maximum annual temperature, minimum annual temperature and average annual temperature. For each study tree, we generated Pearson correlation coefficients between ring width indices from each position and six climate parameters. We also investigated whether the number of missing rings differed among positions and bole heights. We found that tree density did not significantly influence climatic sensitivity to any of the climate parameters investigated at any of the sample positions. Results from three types of analyses suggest that climatic sensitivity of tree growth varied with position height: (i) correlations of radial growth and climate variables consistently increased with height; (ii) model strength based on Akaike's information criterion increased with height, where treetop growth consistently had the highest sensitivity and coarse roots the lowest sensitivity to each climatic parameter; and (iii) the correlation between bole ring width indices decreased with distance between positions. We speculate that increased sensitivity to climate at higher positions is related to hydraulic limitation because higher positions experience greater xylem tensions due to gravitational effects that render these positions more sensitive to climatic stresses. The low sensitivity of root growth to all climatic variables

  3. High severity fires, positive fire feedbacks and alternative stable states in Athrotaxis rainforest ecosystems in western Tasmania.

    Science.gov (United States)

    Holz, A.; Wood, S.; Fletcher, M. S.; Ward, C.; Hopf, F.; Veblen, T. T.; Bowman, D. M. J. S.

    2016-12-01

    Recurrent landscape fires present a powerful selective force on plant regeneration strategies that form a continuum between vegetative resprouters and obligate seeders. In the latter case, reduction of the interval between fires, combined with factors that affect plant traits and regeneration dynamics can drive plant population to local extinction. Here we use Athrotaxis selaginoides, a relict fire-sensitive Gondwanan tree species that occurs in western Tasmania, as model system to investigate the putative impacts of climate change and variability and human management of fire. We integrate landscape ecology (island-wide scale), with field survey and dendrochronology (stand-scale) and sedimentary records (watershed and landscape-scales) to garner a better understanding of the timing and impact of landscape fire on the vegetation dynamics of Athrotaxis at multiple scales. Across the species range sedimentary charcoal and pollen concentrations indicate that the recovery time since the last fire has consistently lengthened over the last 10,000 yrs. Stand-scale tree-age and fire-scar reconstructions suggest that populations of the Athrotxis have survive very infrequent landscape fires over the last 4-6 centuries, but that fire severity has increased following European colonization causing population collapse of Athrotaxis and an associate shift in stand structure and composition that favor resprouter species over obligate seeders. Overall our findings suggest that the resistance to fires and postfire recovery of populations of A. selaginoides have gradually declined throughout the Holocene and rapidly declined after Europeans altered fire regimes, a trend that matches the fate other Gondwanan conifers in temperate rainforests elsewhere in the southern Hemisphere.

  4. Season-specific climate signal and reconstruction from a new tree-ring network in the southwestern U.S

    Science.gov (United States)

    Griffin, D.; Woodhouse, C. A.; Meko, D. M.; Stahle, D. W.; Faulstich, H.; Leavitt, S. W.; Touchan, R.; Castro, C. L.; Carrillo, C.

    2011-12-01

    Our research group has updated existing tree-ring collections from over 50 sampling sites in the southwestern U.S. The new and archived specimens, carefully dated with dendrochronology, have been analyzed for width variations of "earlywood" and "latewood." These are the two components of annual rings in conifers that form in spring and summer, respectively. The network of primary tree-ring data has been used to develop a suite of well-replicated chronologies that extend through the 2008 growing season and are sensitive to the season-specific climate variability of the Southwest. Correlation function analysis indicates that the earlywood chronologies are closely related to cool season (October-April) precipitation variability and the chronologies derived from latewood are generally sensitive to precipitation and temperature conditions during the warm season (June-August). These proxy data originate from biological organisms and are not without bias; however, they do constitute a new means for evaluating the recent paleoclimatic history of the North American summer monsoon. The monsoon is a major component of the region's climate, impacting social and environmental systems and delivering up to 60% of the annual precipitation in the southwestern U.S. We have developed latewood-based retrodictions of monsoon precipitation that explain over half of the variance in the instrumental record, pass standard verification tests, and point to periods of persistent drought and wetness during the last 300-500 years. These reconstructions are being used to evaluate the monsoon's long-term spatiotemporal variability and its relationship to cool season climate and the major modes of ocean-atmosphere variability.

  5. Millennium-scale crossdating and inter-annual climate sensitivities of standing California redwoods.

    Directory of Open Access Journals (Sweden)

    Allyson L Carroll

    Full Text Available Extremely decay-resistant wood and fire-resistant bark allow California's redwoods to accumulate millennia of annual growth rings that can be useful in biological research. Whereas tree rings of Sequoiadendron giganteum (SEGI helped formalize the study of dendrochronology and the principle of crossdating, those of Sequoia sempervirens (SESE have proven much more difficult to decipher, greatly limiting dendroclimatic and other investigations of this species. We overcame these problems by climbing standing trees and coring trunks at multiple heights in 14 old-growth forest locations across California. Overall, we sampled 1,466 series with 483,712 annual rings from 120 trees and were able to crossdate 83% of SESE compared to 99% of SEGI rings. Standard and residual tree-ring chronologies spanning up to 1,685 years for SESE and 1,538 years for SEGI were created for each location to evaluate crossdating and to examine correlations between annual growth and climate. We used monthly values of temperature, precipitation, and drought severity as well as summer cloudiness to quantify potential drivers of inter-annual growth variation over century-long time series at each location. SESE chronologies exhibited a latitudinal gradient of climate sensitivities, contrasting cooler northern rainforests and warmer, drier southern forests. Radial growth increased with decreasing summer cloudiness in northern rainforests and a central SESE location. The strongest dendroclimatic relationship occurred in our southernmost SESE location, where radial growth correlated negatively with dry summer conditions and exhibited responses to historic fires. SEGI chronologies showed negative correlations with June temperature and positive correlations with previous October precipitation. More work is needed to understand quantitative relationships between SEGI radial growth and moisture availability, particularly snowmelt. Tree-ring chronologies developed here for both redwood

  6. AMS 14C measurements for tree-ring samples from Japanese woods from 4c AD to 8c AD

    International Nuclear Information System (INIS)

    Ozaki, Hiromasa; Sakamoto, Minoru; Imamura, Mineo; Mitsutani, Takumi

    2010-01-01

    Regional offsets of atmospheric 14 C concentration, as represented by differences from IntCal calibration datasets, are discussed at times in relation to universal use of international radiocarbon calibration curve. In the construction of IntCal, 14 C contents of contemporaneous tree-ring samples from different regions in the northern hemisphere have been used, because the regional differences were indistinguishable from errors of measurements. Nowadays, high-precision 14 C results can be obtained much more easily than before, so more attention should be paid to the possible regional offsets. Most parts of IntCal has been constructed by using 14 C contents of tree-ring samples from woods in high latitude of Europe and North America, which are farthest from Japan in the northern hemisphere. So far, we have measured 14 C contents of tree-ring samples from Japanese wood samples dendrochronologically dated from 11th century BC to 4th century AD in order to investigate regional offset in Japan. Although the obtained results agreed well with IntCal in general, there were some periods when the 14 C contents differ significantly from IntCal. In this paper, we report the new results of AMS 14 C measurement for Japanese tree-ring samples ranging from 4th century AD to 8th century AD. The results show a significant disagreement with IntCal at around 630 AD. Similar difference was indicated by 14 C contents of tree-ring samples from other Japanese woods (Imamura et al., 2007). So it is certain that the regional offset in Japan exists at around 630 AD. (author)

  7. Which climate change path are we following? Bad news from Scots pine.

    Science.gov (United States)

    Bombi, Pierluigi; D'Andrea, Ettore; Rezaie, Negar; Cammarano, Mario; Matteucci, Giorgio

    2017-01-01

    Current expectations on future climate derive from coordinated experiments, which compile many climate models for sampling the entire uncertainty related to emission scenarios, initial conditions, and modelling process. Quantifying this uncertainty is important for taking decisions that are robust under a wide range of possible future conditions. Nevertheless, if uncertainty is too large, it can prevent from planning specific and effective measures. For this reason, reducing the spectrum of the possible scenarios to a small number of one or a few models that actually represent the climate pathway influencing natural ecosystems would substantially increase our planning capacity. Here we adopt a multidisciplinary approach based on the comparison of observed and expected spatial patterns of response to climate change in order to identify which specific models, among those included in the CMIP5, catch the real climate variation driving the response of natural ecosystems. We used dendrochronological analyses for determining the geographic pattern of recent growth trends for three European species of trees. At the same time, we modelled the climatic niche for the same species and forecasted the suitability variation expected across Europe under each different GCM. Finally, we estimated how well each GCM explains the real response of ecosystems, by comparing the expected variation with the observed growth trends. Doing this, we identified four climatic models that are coherent with the observed trends. These models are close to the highest range limit of the climatic variations expected by the ensemble of the CMIP5 models, suggesting that current predictions of climate change impacts on ecosystems could be underestimated.

  8. Which climate change path are we following? Bad news from Scots pine.

    Directory of Open Access Journals (Sweden)

    Pierluigi Bombi

    Full Text Available Current expectations on future climate derive from coordinated experiments, which compile many climate models for sampling the entire uncertainty related to emission scenarios, initial conditions, and modelling process. Quantifying this uncertainty is important for taking decisions that are robust under a wide range of possible future conditions. Nevertheless, if uncertainty is too large, it can prevent from planning specific and effective measures. For this reason, reducing the spectrum of the possible scenarios to a small number of one or a few models that actually represent the climate pathway influencing natural ecosystems would substantially increase our planning capacity. Here we adopt a multidisciplinary approach based on the comparison of observed and expected spatial patterns of response to climate change in order to identify which specific models, among those included in the CMIP5, catch the real climate variation driving the response of natural ecosystems. We used dendrochronological analyses for determining the geographic pattern of recent growth trends for three European species of trees. At the same time, we modelled the climatic niche for the same species and forecasted the suitability variation expected across Europe under each different GCM. Finally, we estimated how well each GCM explains the real response of ecosystems, by comparing the expected variation with the observed growth trends. Doing this, we identified four climatic models that are coherent with the observed trends. These models are close to the highest range limit of the climatic variations expected by the ensemble of the CMIP5 models, suggesting that current predictions of climate change impacts on ecosystems could be underestimated.

  9. Temperature and rainfall strongly drive temporal growth variation in Asian tropical forest trees.

    Science.gov (United States)

    Vlam, Mart; Baker, Patrick J; Bunyavejchewin, Sarayudh; Zuidema, Pieter A

    2014-04-01

    Climate change effects on growth rates of tropical trees may lead to alterations in carbon cycling of carbon-rich tropical forests. However, climate sensitivity of broad-leaved lowland tropical trees is poorly understood. Dendrochronology (tree-ring analysis) provides a powerful tool to study the relationship between tropical tree growth and annual climate variability. We aimed to establish climate-growth relationships for five annual-ring forming tree species, using ring-width data from 459 canopy and understory trees from a seasonal tropical forest in western Thailand. Based on 183/459 trees, chronologies with total lengths between 29 and 62 years were produced for four out of five species. Bootstrapped correlation analysis revealed that climate-growth responses were similar among these four species. Growth was significantly negatively correlated with current-year maximum and minimum temperatures, and positively correlated with dry-season precipitation levels. Negative correlations between growth and temperature may be attributed to a positive relationship between temperature and autotrophic respiration rates. The positive relationship between growth and dry-season precipitation levels likely reflects the strong water demand during leaf flush. Mixed-effect models yielded results that were consistent across species: a negative effect of current wet-season maximum temperatures on growth, but also additive positive effects of, for example, prior dry-season maximum temperatures. Our analyses showed that annual growth variability in tropical trees is determined by a combination of both temperature and precipitation variability. With rising temperature, the predominantly negative relationship between temperature and growth may imply decreasing growth rates of tropical trees as a result of global warming.

  10. Disparate effects of global-change drivers on mountain conifer forests: warming-induced growth enhancement in young trees vs. CO2 fertilization in old trees from wet sites.

    Science.gov (United States)

    Camarero, J Julio; Gazol, Antonio; Galván, Juan Diego; Sangüesa-Barreda, Gabriel; Gutiérrez, Emilia

    2015-02-01

    Theory predicts that the postindustrial rise in the concentration of CO2 in the atmosphere (c(a)) should enhance tree growth either through a direct fertilization effect or indirectly by improving water use efficiency in dry areas. However, this hypothesis has received little support in cold-limited and subalpine forests where positive growth responses to either rising ca or warmer temperatures are still under debate. In this study, we address this issue by analyzing an extensive dendrochronological network of high-elevation Pinus uncinata forests in Spain (28 sites, 544 trees) encompassing the whole biogeographical extent of the species. We determine if the basal area increment (BAI) trends are linked to climate warming and increased c(a) by focusing on region- and age-dependent responses. The largest improvement in BAI over the past six centuries occurred during the last 150 years affecting young trees and being driven by recent warming. Indeed, most studied regions and age classes presented BAI patterns mainly controlled by temperature trends, while growing-season precipitation was only relevant in the driest sites. Growth enhancement was linked to rising ca in mature (151-300 year-old trees) and old-mature trees (301-450 year-old trees) from the wettest sites only. This finding implies that any potential fertilization effect of elevated c(a) on forest growth is contingent on tree features that vary with ontogeny and it depends on site conditions (for instance water availability). Furthermore, we found widespread growth decline in drought-prone sites probably indicating that the rise in ca did not compensate for the reduction in water availability. Thus, warming-triggered drought stress may become a more important direct driver of growth than rising ca in similar subalpine forests. We argue that broad approaches in biogeographical and temporal terms are required to adequately evaluate any effect of rising c(a) on forest growth. © 2014 John Wiley & Sons Ltd.

  11. Interactions between Shrubs and Permafrost in the Torngat Mountains, Northern Labrador, Canada

    Science.gov (United States)

    Lewkowicz, A.; Way, R. G.; Hermanutz, L.; Trant, A.; Siegwart Collier, L.; Whitaker, D.

    2017-12-01

    Discontinuous permafrost is acutely sensitive to climate warming and vegetation dynamics. Shrub height is positively correlated with accumulation of snow in the tundra resulting in warming of the ground in winter, and greater shading and lower surface temperatures in summer. Rapid greening due to climate warming has been observed throughout northeastern Canada and particularly in the coastal mountainous terrain of the Torngat Mountains National Park. Our research examines how this shrubification in the Torngat Mountains is modifying permafrost characteristics using observations which extend over a 100 km south-north transect from the sporadic zone (Saglek, Torr Bay) to where permafrost is widespread (Nakvak Brook, Kangalaksiorvik Lake) and potentially continuous (Komaktorvik River). We use air and ground temperature monitoring, vegetation surveys, dendrochronology, frost probing and electrical resistivity tomography (ERT) to describe the complex interactions between shrub growth, geomorphology, climate and permafrost in a region where climate warming is rapidly altering the landscape. Preliminary analysis of field data shows low resistivity anomalies in the ERT profiles at some sites with thin permafrost, interpreted as unfrozen zones correlated with areas of tall shrubs (Alnus spp., Salix spp. and Betula glandulosa; ranging from prostrate to 2 m). Elsewhere, high resistivities extend to the base of the ERT profiles, indicating thicker permafrost, and no obvious impact of medium to low-prostrate shrubs (Salix spp., Betula glandulosa, Rhododendron spp., and Vaccinium spp.; up to 50 cm). Permafrost is interpreted to be present at most sites with low or prostrate shrubs, except where hydrological conditions favour warmer ground temperatures. We infer that the net impact of increasing shrub heights on the active layer and permafrost depends on antecedent ground temperatures and surficial geology. Increasing shrub heights may cause permafrost degradation at sites where

  12. Can forest dieback and tree death be predicted by prior changes in wood anatomy?

    Science.gov (United States)

    Colangelo, Michele; Julio Camarero, Jesus; De Micco, Veronica; Borghetti, Marco; Gentilesca, Tiziana; Sanchez-Salguero, Raul; Ripullone, Francesco

    2017-04-01

    Climate warming is expected to amplify drought stress resulting in more intense and widespread dieback episodes and increasing mortality rates. Studies on quantitative wood anatomy and dendrochronology have demonstrated their potential to supply useful information on the causes of tree decline, although this approach is basically observational and retrospective. Moreover, the long-term reconstruction of wood anatomical features, strictly linked to the evolution of xylem anatomy plasticity through time, allow investigating hydraulic adjustments of trees. In this study, we analyzed wood-anatomical variables in two Italian oak forests where recent episodes of dieback and mortality have been reported. We analyzed in coexisting now-dead and living trees the following wood-anatomical variables: annual tree-ring area, earlywood (EW) and latewood (LW) areas, absolute and relative (%) areas occupied by vessels in the EW and LW, EW and LW vessel areas, EW and LW vessel density and vessel diameter classification. We also calculated the hydraulic diameter (Dh) for all vessels measured within each ring by weighting individual conduit diameters to correspond to the average Hagen-Poiseuille lumen theoretical hydraulic conductivity for a vessel size. Wood-anatomical analyses showed that declining and dead trees were more sensitive to drought stress compared to non declining trees, indicating different susceptibility to water shortage between trees. Dead trees did not form earlywood vessels with smaller lumen diameter than surviving trees but tended to form wider latewood vessels with a higher percentage of vessel area. We discuss the results and implications focusing on those proved more sensitive to the phenomena of decline and mortality.

  13. Analytical characterization of the palette and painting techniques of Jorge Afonso, the great 16th century Master of Lisbon painting workshop

    Science.gov (United States)

    Antunes, Vanessa; Candeias, António; Mirão, José; Carvalho, Maria L.; Dias, Cristina Barrocas; Manhita, Ana; Cardoso, Ana; Francisco, Maria J.; Lauw, Alexandra; Manso, Marta

    2018-03-01

    In this work, a study on a set of paintings from the most significant altarpiece assigned to Master Jorge Afonso (c. 1470-1540) painting workshop is presented. This altarpiece is composed by fourteen paintings made to the church of Convento de Jesus, in Setúbal, Portugal, and was made circa 1517-19/1530, according to art-history. This set of paintings is compared to one of the other most important Portuguese altarpieces from the 16th century: the panels of the Round Church of the Convento de Cristo, in Tomar, made circa 1510-1515. The aim of this study is to characterize the wooden support, pigments, ground layers materials and technique used in Jorge Afonso workshop by means of complementary analyses. A dendrochronological approach was made in order to corroborate (or not) the historical date initially assigned. Infrared photography (IRP) and reflectography (IRR) allowed the study of the underdrawing technique and macro photography (MP) was used to recognize overlapping layers technique. Cross-sections from the paintings were examined by optical microscopy (OM), and analyzed by μ-X-ray diffraction (μ-XRD), Energy Dispersive X-ray Fluorescence spectroscopy (EDXRF), Scanning Electron Microscopy with Energy Dispersive X-ray Spectroscopy (SEM-EDS), micro-Raman spectroscopy (μ-Raman), micro-Fourier Transform Infrared spectroscopy (μ-FTIR), Pyrolysis Gas Chromatography Mass Spectrometry (py-GC/MS). The characterization of the palette and ground layers and the study of the overlapping of paint layers brought a new insight of the adopted painting techniques by the most important group of painters working in Portugal in the 16th century - the Lisbon workshop, leaded by Master Jorge Afonso.

  14. The research station "Vaskiny Dachi", Central Yamal, West Siberia, Russia – a review of 25 years of permafrost studies

    Directory of Open Access Journals (Sweden)

    Marina O. Leibman

    2015-03-01

    Full Text Available The research station "Vaskiny Dachi" on the Yamal Peninsula was established in 1988. Activities aimed at monitoring of permafrost and related environmental features under a relatively low level of nature disturbances caused by gas field development. Cryogenic processes that may affect the environment and their structures have been of primary interest. Landslides are the most common cryogenic processes in Central Yamal in general and also in the proximity of the station. Field surveys of numerous landslides, analysis of their dependence on climatic parameters and their fluctuations resulted in novel classification of cryogenic landslides based on mechanisms of their development. Dating by radiocarbon and dendrochronology allows the separation of cycles of landslide activation. Cryogenic landslides control the development of other processes, such as thermal erosion, river channel erosion and thermokarst. It also affects topography, vegetation pattern, geochemistry of vegetation, ground water and soils. As a result, permafrost parameters, specifically active layer depth and ground temperature, moisture and ice content in the active layer, depend indirectly on landsliding. Monitoring within the framework of the main programs of the International Permafrost Association, such as Circumarctic Active Layer Monitoring (CALM, since 1993 and Thermal State of Permafrost (TSP, since 2011, play an important role among the research activities. From the collected data one can conclude that ground temperature increased on average by about 1 °C since the 1990s. At the same time, active layer fluctuations do not exactly follow the air temperature changes. Spatial changes in ground temperature are controlled by the redistribution of snow which is resulting from strong winds characteristic for tundra environments and the highly dissected relief of Central Yamal. Temporal variations rather depend on air temperature fluctuations but the rate differs in various

  15. Impact of Climate Trends and Drought Events on the Growth of Oaks (Quercus robur L. and Quercus petraea (Matt. Liebl. within and beyond Their Natural Range

    Directory of Open Access Journals (Sweden)

    Diana Perkins

    2018-02-01

    Full Text Available Due to predicted climate change, it is important to know to what extent trees and forests will be impacted by chronic and episodic drought stress. As oaks play an important role in European forestry, this study focuses on the growth response of sessile oak (Quercus petraea (Matt. Liebl. and pedunculate oak (Quercus robur (L. under contrasting climatic conditions. Analyses cover both site conditions of their natural occurrence (Southern Germany and Northeast Italy and site conditions beyond their natural range (South Africa. The sites beyond their natural range represent possible future climate conditions. Tree-ring series from three different sites were compared and analysed using dendrochronological methods. The long-term growth development of oak trees appears to be similar across the sites, yet the growth level over time is higher in the drier and warmer climate than in the temperate zone. When compared with previous growth periods, growth models reveal that oak trees grew more than expected during the last decades. A recent setback in growth can be observed, although growth is still higher than the model predicts. By focusing on the short-term reactions of the trees, distinct drought events and periods were discovered. In each climatic region, similar growth reactions developed after drought periods. A decline in growth rate occurred in the second or third year after the drought event. Oaks in South Africa are currently exposed to a warmer climate with more frequent drought events. This climatic condition is a future prediction also for Europe. In view of this climate change, we discuss the consequences of the long- and short- term growth behaviour of oaks grown in the climate of South Africa for a tree species selection that naturally occurs in Europe.

  16. Differential Growth Responses to Water Balance of Coexisting Deciduous Tree Species Are Linked to Wood Density in a Bolivian Tropical Dry Forest

    Science.gov (United States)

    Mendivelso, Hooz A.; Camarero, J. Julio; Royo Obregón, Oriol; Gutiérrez, Emilia; Toledo, Marisol

    2013-01-01

    A seasonal period of water deficit characterizes tropical dry forests (TDFs). There, sympatric tree species exhibit a diversity of growth rates, functional traits, and responses to drought, suggesting that each species may possess different strategies to grow under different conditions of water availability. The evaluation of the long-term growth responses to changes in the soil water balance should provide an understanding of how and when coexisting tree species respond to water deficit in TDFs. Furthermore, such differential growth responses may be linked to functional traits related to water storage and conductance. We used dendrochronology and climate data to retrospectively assess how the radial growth of seven coexisting deciduous tree species responded to the seasonal soil water balance in a Bolivian TDF. Linear mixed-effects models were used to quantify the relationships between basal area increment and seasonal water balance. We related these relationships with wood density and sapwood production to assess if they affect the growth responses to climate. The growth of all species responded positively to water balance during the wet season, but such responses differed among species as a function of their wood density. For instance, species with a strong growth response to water availability averaged a low wood density which may facilitate the storage of water in the stem. By contrast, species with very dense wood were those whose growth was less sensitive to water availability. Coexisting tree species thus show differential growth responses to changes in soil water balance during the wet season. Our findings also provide a link between wood density, a trait related to the ability of trees to store water in the stem, and wood formation in response to water availability. PMID:24116001

  17. Variability in radial sap flux density patterns and sapwood area among seven co-occurring temperate broad-leaved tree species.

    Science.gov (United States)

    Gebauer, Tobias; Horna, Viviana; Leuschner, Christoph

    2008-12-01

    Forest transpiration estimates are frequently based on xylem sap flux measurements in the outer sections of the hydro-active stem sapwood. We used Granier's constant-heating technique with heating probes at various xylem depths to analyze radial patterns of sap flux density in the sapwood of seven broad-leaved tree species differing in wood density and xylem structure. Study aims were to (1) compare radial sap flux density profiles between diffuse- and ring-porous trees and (2) analyze the relationship between hydro-active sapwood area and stem diameter. In all investigated species except the diffuse-porous beech (Fagus sylvatica L.) and ring-porous ash (Fraxinus excelsior L.), sap flux density peaked at a depth of 1 to 4 cm beneath the cambium, revealing a hump-shaped curve with species-specific slopes. Beech and ash reached maximum sap flux densities immediately beneath the cambium in the youngest annual growth rings. Experiments with dyes showed that the hydro-active sapwood occupied 70 to 90% of the stem cross-sectional area in mature trees of diffuse-porous species, whereas it occupied only about 21% in ring-porous ash. Dendrochronological analyses indicated that vessels in the older sapwood may remain functional for 100 years or more in diffuse-porous species and for up to 27 years in ring-porous ash. We conclude that radial sap flux density patterns are largely dependent on tree species, which may introduce serious bias in sap-flux-derived forest transpiration estimates, if non-specific sap flux profiles are assumed.

  18. Effect of gases and particulate matter from electricity generation process on the radial growth of teak plantations surrounding Mae Moh power plant, Lampang province

    Directory of Open Access Journals (Sweden)

    Narapong Sangram

    2016-03-01

    Full Text Available The objectives of this study were to investigate radial growth patterns and influences of polluting gases and particulate matter on the radial growth of teak plantations surrounding the Mae Moh Power Plant. Twenty-four 32-year-old teak trees were selected from Mae Jang and Mae Moh plantations, which were 5 km and 15 km from the Mae Moe power plant, respectively. Forty-eight sample cores were collected from the 24 trees (two cores per tree. The growth patterns of all the cores were analyzed following the standard methods of dendrochronology. The relationships between the growth pattern and the amounts of sulfur dioxide, nitrogen dioxide, carbon monoxide and particulate matter were measured as average daily rates and then analyzed. The study showed that the best-fit model for the relationship between the radial current annual increment at breast height (CAIdbh and time (Y was an exponential equation. The fitted equations were: CAIdbh = 10.657e(−0.031Y for Mae Moh plantation and CAIdbh = 12.518e(−0.032Y for Mae Jang plantation. The coefficient of determination for the fitted equations was 0.410 and 0.423 for the Mae Moh and Mae Jang plantations, respectively. Moreover, carbon monoxide (CO and sulfur dioxide (SO2 had a statistically significant effect on radial teak growth (RT in the Mae Jang plantation, with a coefficient of determination of 0.69 (RTmj = 0.571 + 0.429(CO − 0.023(SO2.

  19. Dispersal limitation drives successional pathways in Central Siberian forests under current and intensified fire regimes.

    Science.gov (United States)

    Tautenhahn, Susanne; Lichstein, Jeremy W; Jung, Martin; Kattge, Jens; Bohlman, Stephanie A; Heilmeier, Hermann; Prokushkin, Anatoly; Kahl, Anja; Wirth, Christian

    2016-06-01

    Fire is a primary driver of boreal forest dynamics. Intensifying fire regimes due to climate change may cause a shift in boreal forest composition toward reduced dominance of conifers and greater abundance of deciduous hardwoods, with potential biogeochemical and biophysical feedbacks to regional and global climate. This shift has already been observed in some North American boreal forests and has been attributed to changes in site conditions. However, it is unknown if the mechanisms controlling fire-induced changes in deciduous hardwood cover are similar among different boreal forests, which differ in the ecological traits of the dominant tree species. To better understand the consequences of intensifying fire regimes in boreal forests, we studied postfire regeneration in five burns in the Central Siberian dark taiga, a vast but poorly studied boreal region. We combined field measurements, dendrochronological analysis, and seed-source maps derived from high-resolution satellite images to quantify the importance of site conditions (e.g., organic layer depth) vs. seed availability in shaping postfire regeneration. We show that dispersal limitation of evergreen conifers was the main factor determining postfire regeneration composition and density. Site conditions had significant but weaker effects. We used information on postfire regeneration to develop a classification scheme for successional pathways, representing the dominance of deciduous hardwoods vs. evergreen conifers at different successional stages. We estimated the spatial distribution of different successional pathways under alternative fire regime scenarios. Under intensified fire regimes, dispersal limitation of evergreen conifers is predicted to become more severe, primarily due to reduced abundance of surviving seed sources within burned areas. Increased dispersal limitation of evergreen conifers, in turn, is predicted to increase the prevalence of successional pathways dominated by deciduous hardwoods

  20. Peatland pines as a proxy for water table fluctuations: disentangling tree growth, hydrology and possible human influence.

    Science.gov (United States)

    Smiljanić, Marko; Seo, Jeong-Wook; Läänelaid, Alar; van der Maaten-Theunissen, Marieke; Stajić, Branko; Wilmking, Martin

    2014-12-01

    Dendrochronological investigations of Scots pine (Pinus sylvestris L.) growing on Männikjärve peatland in central Estonia showed that annual tree growth of peatland pines can be used as a proxy for past variations of water table levels. Reconstruction of past water table levels can help us to better understand the dynamics of various ecological processes in peatlands, e.g. the formation of vegetation patterns or carbon and nitrogen cycling. Männikjärve bog has one of the longest water table records in the boreal zone, continuously monitored since 1956. Common uncertainties encountered while working with peatland trees (e.g. narrow, missing and wedging rings) were in our case exacerbated with difficulties related to the instability of the relationship between tree growth and peatland environment. We hypothesized that the instable relationship was mainly due to a significant change of the limiting factor, i.e. the rise of the water table level due to human activity. To test our hypothesis we had to use several novel methods of tree-ring chronology analysis as well as to test explicitly whether undetected missing rings biased our results. Since the hypothesis that the instable relationship between tree growth and environment was caused by a change in limiting factor could not be rejected, we proceeded to find possible significant changes of past water table levels using structural analysis of the tree-ring chronologies. Our main conclusions were that peatland pines can be proxies to water table levels and that there were several shifting periods of high and low water table levels in the past 200 years. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Non-Fluvial Controls of Erosion, Sediment Transport and Fluvial Morphology in a mid-Atlantic Piedmont Watershed, White Clay Creek, Pennsylvania, U.S.A.

    Science.gov (United States)

    McCarthy, K.; Affinito, R. A.; Pizzuto, J. E.; Stotts, S.; Henry, T.; Krauthauser, M.; O'Neal, M. A.

    2017-12-01

    Quantifying contemporary sediment budgets is essential for restoration and ecosystem management of mid-Atlantic watersheds, but relevant processes and controls are poorly understood. In the 153 km2 White Clay Creek watershed in southeastern Pennsylvania, longitudinal profiles reflect migration of knickpoints though bedrock over Quaternary timescales. In bank exposures along stream valleys, saprolite, bedrock, and matrix-supported cobbly and bouldery diamicton (likely colluvial) commonly underlie finer-grained clay, silt, sand, and gravel deposits of valley floor depositional environments. Overbank sedimentation rates were quantified by measuring the thickness of sediment deposited over the roots of floodplain trees. The sampled trees range in age from 25-270 years with median sediment accumulation rates of approximately 2 mm/yr (range 0-10 mm/yr). Rates of bank retreat (measured from historical aerial imagery or root-exposure dendrochronology) vary from 6-36 cm/yr, with median rates of 10 cm/yr. While bank erosion rates are subject to a variety of controls, including channel curvature, the density of riparian trees, and freeze-thaw processes, the strongest influence appears to be the grain size and thickness of bouldery diamicton exposed along the toes of retreating banks. Cobbles and boulders supplied by eroding diamicton also mantle the bed of the channel, such that 33- 80% of the bed material remains immobile at bankfull stage. A conceptual model of fluvial processes and sediment budgets for these channels must account for the watershed's history of changing climate, tectonics, and land use, requiring mapping of bedrock, colluvium, former mill dam sediments, and other non-alluvial deposits and controls. Efforts to apply hydraulic geometry principles (requiring a precise adjustment to contemporary hydraulic and sediment regime) or to treat these channels as traditional "threshold" rivers are unlikely to be successful.

  2. X-ray tomographic techniques for the study of cultural heritages

    International Nuclear Information System (INIS)

    Schillaci, T.

    2011-01-01

    In recent years, X-ray Computed Tomography (CT) has become an important tool for investigating all kinds of materials. Due to its non-destructive nature, it is especially suitable to investigate samples that may not be altered or damaged during the course of the investigation. CT has been recently introduced in the field of Cultural Heritage diagnostics, where it can be used for the investigation of different works of art, as it preserves the integrity of the object and gives morphological and physical information on its inner structure. This paper describes a methodological approach on the use of the X-ray CT technique to study items belonging to cultural heritage with the aim to obtain information related to their preservation state and therefore, to plan an adequate conservation and restoration procedure. Significant examples of applications are the study of porosity and pore size distribution and their connectivity for different porous materials and the study of kinetics of capillary fluid absorption in sedimentary rocks. Other applications are relevant to the possibility to investigate in a non-destructive way the presence of defects or fractures inside an object and, not last in order of importance, the possibility to study different typologies of woods or waterlogged woods, the presence of an eventual biodegradation state and the possibility to perform a dendrochronology. In this paper, the results of some case studies, obtained through the integrated use of CT systems with different resolutions, are reported. Other expected future developments will be addressed to the integration of CT data with results of compatible non-destructive techniques.

  3. Structure, development and health status of spruce forests affected by air pollution in the western Krkonoše Mts. in 1979–2014

    Directory of Open Access Journals (Sweden)

    Král Jan

    2015-09-01

    Full Text Available The structure and health status of waterlogged or peaty spruce (Picea abies [L.] Karst. forests in the summit parts of the Krkonoše Mts. in the Czech Republic were studied in 1979–2014. The objective was to evaluate the stand structure, dead wood, trend of the health status and productivity on four permanent research plots (PRP in relation to air pollution (SO2 and NOx concentrations and climatic conditions (temperatures and precipitation amounts. Stand structure was evaluated on the base of the measured parameters of individual trees on PRP. The health status of trees was evaluated according to foliage, and their vitality was assessed according to their radial growth documented by dendrochronological analyses. The radial growth was negatively correlated with SO2 and NOx concentrations. Stand dynamics during the observation period was characterised by increased tree mortality, the presence of dead wood and reduction of stand density from 1983 to 1992, while the most severe impairment of health status and stand stability occurred in 1982–1987. The foliage mass of living trees has been gradually increasing since 1988, but no pronounced improvement of tree vitality was documented after the decrease in SO2 concentration. However, particularly physiologically weakened spruce trees were attacked by the European spruce bark beetle (Ips typographus. The process of forest damage is manifested not only by foliage reduction but also by symptoms of various necroses on the assimilatory organs. In terms of climatic data, the weather in April had the most important effect on radial growth. Diameter increment showed positive statistically significant correlation with temperature in growing season, but the precipitation effect was low.

  4. Sedimentary rhythms in coastal dunes as a record of intra-annual changes in wind climate (Łeba, Poland)

    Science.gov (United States)

    Ludwig, J.; Lindhorst, S.; Betzler, C.; Bierstedt, S. E.; Borówka, R. K.

    2017-08-01

    It is shown that coastal dunes bear a so far unread archive of annual wind intensity. Active dunes at the Polish coast near Łeba consist of two genetic units: primary dunes with up to 18 m high eastward-dipping foresets, temporarily superimposed by smaller secondary dunes. Ground-penetrating radar (GPR) data reveal that the foresets of the primary dunes are bundled into alternating packages imaged as either low- or high-amplitude reflections. High-amplitude packages are composed of quartz sand with intercalated heavy-minerals layers. Low-amplitude packages lack these heavy-mineral concentrations. Dune net-progradation is towards the east, reflecting the prevalence of westerly winds. Winds blowing parallel to the dune crest winnow the lee slope, leaving layers enriched in heavy minerals. Sediment transport to the slip face of the dunes is enhanced during the winter months, whereas winnowing predominantly takes place during the spring to autumn months, when the wind field is bi-directional. As a consequence of this seasonal shift, the sedimentary record of one year comprises one low- and one high-amplitude GPR reflection interval. This sedimentary pattern is a persistent feature of the Łeba dunes and recognized to resemble a sedimentary "bar code". To overcome hiatuses in the bar code of individual dunes and dune-to-dune variations in bar-code quality, dendrochronological methods were adopted to compile a composite bar code from several dunes. The resulting data series shows annual variations in west-wind intensity at the southern Baltic coast for the time period 1987 to 2012. Proxy-based wind data are validated against instrumental based weather observations.

  5. Acid deposition and water use efficiency in Appalachian forests

    Science.gov (United States)

    Malcomb, J.

    2017-12-01

    Multiple studies have reported increases in forest water use efficiency in recent decades, but the drivers of these trends remain uncertain. While acid deposition has profoundly altered the biogeochemistry of Appalachian forests in the past century, its impacts on forest water use efficiency have been largely overlooked. Plant ecophysiology literature suggests that plants up-regulate transpiration in response to soil nutrient limitation in order to maintain sufficient mass flow of nutrients. To test the impacts of acid deposition on forest eco-hydrology in central Appalachia, we integrated dendrochronological techniques, including tree ring δ13C analysis, with catchment water balance data from the Fernow Experimental Forest in West Virginia. Tree cores from four species were collected in Fernow Watershed 3, which has received experimental ammonium sulfate additions since 1989, and Watershed 7, an adjacent control catchment. Initial results suggest that acidification treatments have not significantly influenced tree productivity compared to a control watershed, but the effect varies by species, with tulip poplar showing greatest sensitivity to acidification. Climatic water balance, defined as the difference between growing season precipitation and evapotranspiration, is significantly related to annual tree ring growth, suggesting that climate may be driving tree growth trends in chronically acidified Appalachian forests. Tree ring 13C analysis from Fernow cores is underway and these data will be integrated with catchment hydrology data from five other sites in central Appalachia and the U.S. Northeast, representing a range of forest types, soil base saturations, and acid deposition histories. This work will advance understanding of how climate and acid deposition interact to influence forest productivity and water use efficiency, and improve our ability to model carbon and water cycling in forested ecosystems impacted by acid deposition.

  6. Disturbance legacies and climate jointly drive tree growth and mortality in an intensively studied boreal forest

    Energy Technology Data Exchange (ETDEWEB)

    Bond-Lamberty, Benjamin; Rocha, Adrian; Calvin, Katherine V.; Holmes, Bruce; Wang, Chuankuan; Goulden, Michael L.

    2014-01-01

    How will regional growth and mortality change with even relatively small climate shifts, even independent of catastrophic disturbances? This question is particularly acute for the North American boreal forest, which is carbon-dense and subject The goals of this study were to combine dendrochronological sampling, inventory records, and machine-learning algorithms to understand how tree growth and death have changed at one highly studied site (Northern Old Black Spruce, NOBS) in the central Canadian boreal forest. Over the 1999-2012 inventory period, mean DBH increased even as stand density and basal area declined significantly from 41.3 to 37.5 m2 ha-1. Tree mortality averaged 1.4±0.6% yr-1, with most mortality occurring in medium-sized trees. A combined tree ring chronology constructed from 2001, 2004, and 2012 sampling showed several periods of extreme growth depression, with increased mortality lagging depressed growth by ~5 years. Minimum and maximum air temperatures exerted a negative influence on tree growth, while precipitation and climate moisture index had a positive effect; both current- and previous-year data exerted significant effects. Models based on these variables explained 23-44% of the ring-width variability. There have been at least one, and probably two, significant recruitment episodes since stand initiation, and we infer that past climate extremes led to significant NOBS mortality still visible in the current forest structure. These results imply that a combination of successional and demographic processes, along with mortality driven by abiotic factors, continue to affect the stand, with significant implications for our understanding of previous work at NOBS and the sustainable management of regional forests.

  7. Dendroclimatic analysis of Pinus pseudostrobus and Pinus devoniana in the municipalities of Áporo and Zitácuaro (Michoacán, Monarch Butterfly Biosphere Reserve

    Directory of Open Access Journals (Sweden)

    Jaume Marlès Magre

    2015-12-01

    Full Text Available This article presents the first study on dendroclimatology of Pinus pseudostrobus and Pinus devoniana in the state of Michoacán (Mexico, specifically in the municipalities of Áporo and Zitácuaro, both municipalities within the Monarch Butterfly Biosphere Reserve (MBBR. The sampling in Áporo, northwest of the MBBR, was held in Los Ejidos del Rincón del Soto and Arroyo Seco, in Sierra Chincúa (May 2011. In Zitácuaro, southwest of the reserve, a sampling was performed in the Ejido de San Juan de Zitácuaro, in the area of Ocotal and Palma, and Meso Sedano (June 2011. There were a total of 38 Pinus pseudostrobus and 12 Pinus devoniana sampled in both areas of the study and distributed in 28 trees in the municipality of Áporo and 22 in Zitácuaro. Two samples per tree were taken at 1.3 m height, resulting in a total of 100 tree cores. The dendrochronological series in Áporo for the species Pinus pseudostrobus were extended to 62 years (1949-2010 and for Pinus devoniana 86 years (1925-2010; and the series in Zitácuaro for Pinus pseudostrobus and Pinus devoniana were extended to 47 years (1964-2010 and 44 years (1967-2010, respectively. The ring chronologies were validated using the program COFECHA, which calculates the cross correlations between individual series of the tree-growth, five series were eliminated due to very low or negative correlations. The climate data from Zitácuaro were obtained from two weather stations located in the same municipality. And, in the case of Áporo, the data was obtained from stations located in Senguio. The growth rates related to the climate were obtained by removing the growth trend of each tree due to the age, size and other factors such as the competition, using the program ARSTAN. The following statistics were used to evaluate the quality of the residual chronologies and to determine the potential dendrochronology of species for the different populations: the average correlation between series (Rbar

  8. Tree growth and competition in an old-growth Picea abies forest of boreal Sweden: influence of tree spatial patterning

    Science.gov (United States)

    Fraver, Shawn; D'Amato, Anthony W.; Bradford, John B.; Jonsson, Bengt Gunnar; Jönsson, Mari; Esseen, Per-Anders

    2013-01-01

    Question: What factors best characterize tree competitive environments in this structurally diverse old-growth forest, and do these factors vary spatially within and among stands? Location: Old-growth Picea abies forest of boreal Sweden. Methods: Using long-term, mapped permanent plot data augmented with dendrochronological analyses, we evaluated the effect of neighbourhood competition on focal tree growth by means of standard competition indices, each modified to include various metrics of trees size, neighbour mortality weighting (for neighbours that died during the inventory period), and within-neighbourhood tree clustering. Candidate models were evaluated using mixed-model linear regression analyses, with mean basal area increment as the response variable. We then analysed stand-level spatial patterns of competition indices and growth rates (via kriging) to determine if the relationship between these patterns could further elucidate factors influencing tree growth. Results: Inter-tree competition clearly affected growth rates, with crown volume being the size metric most strongly influencing the neighbourhood competitive environment. Including neighbour tree mortality weightings in models only slightly improved descriptions of competitive interactions. Although the within-neighbourhood clustering index did not improve model predictions, competition intensity was influenced by the underlying stand-level tree spatial arrangement: stand-level clustering locally intensified competition and reduced tree growth, whereas in the absence of such clustering, inter-tree competition played a lesser role in constraining tree growth. Conclusions: Our findings demonstrate that competition continues to influence forest processes and structures in an old-growth system that has not experienced major disturbances for at least two centuries. The finding that the underlying tree spatial pattern influenced the competitive environment suggests caution in interpreting traditional tree

  9. Downstream impacts of a Central Amazonian hydroelectric dam on tree growth and mortality in floodplain forests

    Science.gov (United States)

    Resende, A. F. D.; Silva, T. S. F.; Silva, J. D. S.; Piedade, M. T. F.; Streher, A. S.; Ferreira-Ferreira, J.; Schongart, J.

    2017-12-01

    The flood pulse of large Amazonian Rivers is characterized by predictable high- and low-water periods during the annual cycle, and is the main driving force in the floodplains regulating decomposition, nutrient cycles, productivity, life cycles and growth rhythms of floodplains' biota. Over at least 20 millions of years, tree species in these ecosystems developed complex adaptative mechanisms to tolerate flooding, such as the tree species Macrolobium acaciifolium (Fabaceae) and Eschweilera tenuifolia (Lecythidaceae) occupying the lower topographic positions in the floodplain forests along the oligothrophic black-water rivers. Tree growth occurs mainly during terrestrial phase, while during the aquatic phase the anoxic conditions result into a cambial dormancy and formation of annual tree rings. The hydroelectric dam Balbina which was installed in the Uatumã River (central Amazonia) during the 1980s altered significantly the flood pulse regime resulting into higher minimum and lower maximum annual water levels. The suppression of the terrestrial phase caused large-scale mortality of flood-adapted trees growing on the lower topographic positions, as evidenced by radiocarbon dating and cross-dating techniques (dendrochronology). In this study we estimated the extension of dead forests using high resolution ALOS/PALSAR radar images, for their detection along a fluvial distance of more than 280 km downstream of the power plant. Further we analyzed tree growth of 60 living individuals of E. tenuifolia by tree-ring analyses comparing the post- and pre-dam periods. We evaluated the impacts of the altered hydrological regime on tree growth considering ontogenetic effects and the fluvial distance of the trees to the dam. Since the Balbina power plant started operating the associated igapó forests lost about 11% of its cover. We found a significant reduction of tree growth of E. tenuifolia during the post-dam period as a consequence of the increasing aquatic phase duration

  10. Variable effects of climate on forest growth in relation to climate extremes, disturbance, and forest dynamics

    Science.gov (United States)

    Itter, Malcolm S.; Finley, Andrew O.; D'Amato, Anthony W.; Foster, Jane R.; Bradford, John B.

    2017-01-01

    Changes in the frequency, duration, and severity of climate extremes are forecast to occur under global climate change. The impacts of climate extremes on forest productivity and health remain difficult to predict due to potential interactions with disturbance events and forest dynamics—changes in forest stand composition, density, size and age structure over time. Such interactions may lead to non-linear forest growth responses to climate involving thresholds and lag effects. Understanding how forest dynamics influence growth responses to climate is particularly important given stand structure and composition can be modified through management to increase forest resistance and resilience to climate change. To inform such adaptive management, we develop a hierarchical Bayesian state space model in which climate effects on tree growth are allowed to vary over time and in relation to past climate extremes, disturbance events, and forest dynamics. The model is an important step toward integrating disturbance and forest dynamics into predictions of forest growth responses to climate extremes. We apply the model to a dendrochronology data set from forest stands of varying composition, structure, and development stage in northeastern Minnesota that have experienced extreme climate years and forest tent caterpillar defoliation events. Mean forest growth was most sensitive to water balance variables representing climatic water deficit. Forest growth responses to water deficit were partitioned into responses driven by climatic threshold exceedances and interactions with insect defoliation. Forest growth was both resistant and resilient to climate extremes with the majority of forest growth responses occurring after multiple climatic threshold exceedances across seasons and years. Interactions between climate and disturbance were observed in a subset of years with insect defoliation increasing forest growth sensitivity to water availability. Forest growth was particularly

  11. Host heterogeneity influences the impact of a non-native disease invasion on populations of a foundation tree species

    Science.gov (United States)

    Jules, Erik S.; Carroll, Allyson L.; Garcia, Andrea M.; Steenbock, Christopher M.; Kauffman, Matthew J.

    2014-01-01

    Invasive pathogens are becoming increasingly important in forested ecosystems, yet they are often difficult to study because of their rapid transmission. The rate and extent of pathogen spread are thought to be partially controlled by variation in host characteristics, such as when host size and location influence susceptibility. Few host-pathogen systems, however, have been used to test this prediction. We used Port Orford cedar (Chamaecyparis lawsoniana), a foundation tree species in riparian areas of California and Oregon (USA), and the invasive oomycete Phytophthora lateralis to assess pathogen impacts and the role of host characteristics on invasion. Across three streams that had been infected for 13–18 years by P. lateralis, we mapped 2241 trees and determined whether they had been infected using dendrochronology. The infection probability of trees was governed by host size (diameter at breast height [DBH]) and geomorphic position (e.g., active channel, stream bank, floodplain, etc.) similarly across streams. For instance, only 23% of trees <20 cm DBH were infected, while 69% of trees ≥20 cm DBH were infected. Presumably, because spores of P. lateralis are transported downstream in water, they are more likely to encounter well-developed root systems of larger trees. Also because of this water-transport of spores, differences in infection probability were found across the geomorphic positions: 59% of cedar in the active channel and the stream bank (combined) were infected, while 23% of trees found on higher geomorphic types were infected. Overall, 32% of cedar had been infected across the three streams. However, 63% of the total cedar basal area had been killed, because the greatest number of trees, and the largest trees, were found in the most susceptible positions. In the active channel and stream bank, 91% of the basal area was infected, while 46% was infected across higher geomorphic positions. The invasion of Port Orford cedar populations by

  12. A statistical-dynamical modeling approach for the simulation of local paleo proxy records using GCM output

    Energy Technology Data Exchange (ETDEWEB)

    Reichert, B.K.; Bengtsson, L. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Aakesson, O. [Sveriges Meteorologiska och Hydrologiska Inst., Norrkoeping (Sweden)

    1998-08-01

    Recent proxy data obtained from ice core measurements, dendrochronology and valley glaciers provide important information on the evolution of the regional or local climate. General circulation models integrated over a long period of time could help to understand the (external and internal) forcing mechanisms of natural climate variability. For a systematic interpretation of in situ paleo proxy records, a combined method of dynamical and statistical modeling is proposed. Local 'paleo records' can be simulated from GCM output by first undertaking a model-consistent statistical downscaling and then using a process-based forward modeling approach to obtain the behavior of valley glaciers and the growth of trees under specific conditions. The simulated records can be compared to actual proxy records in order to investigate whether e.g. the response of glaciers to climatic change can be reproduced by models and to what extent climate variability obtained from proxy records (with the main focus on the last millennium) can be represented. For statistical downscaling to local weather conditions, a multiple linear forward regression model is used. Daily sets of observed weather station data and various large-scale predictors at 7 pressure levels obtained from ECMWF reanalyses are used for development of the model. Daily data give the closest and most robust relationships due to the strong dependence on individual synoptic-scale patterns. For some local variables, the performance of the model can be further increased by developing seasonal specific statistical relationships. The model is validated using both independent and restricted predictor data sets. The model is applied to a long integration of a mixed layer GCM experiment simulating pre-industrial climate variability. The dynamical-statistical local GCM output within a region around Nigardsbreen glacier, Norway is compared to nearby observed station data for the period 1868-1993. Patterns of observed

  13. Catastrophic wind damage to North American forests and the potential impact of climate change

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, C.J. [Department of Botany, 2502 Plant Sciences Building, University of Georgia, Athens, GA 30602-7271 (United States)

    2000-11-15

    incomplete, and climate-change model predictions sufficiently coarse, that predictions of changes in frequency, size, intensity, or timing of these extreme events must be regarded as highly uncertain. Moreover, retrospective approaches that employ tree demography and dendrochronology require prohibitively large sample sizes to resolve details of the relationship between climate fluctuations and characteristics of these storms. To improve predictions of changes in the climatology of these storms, we need improved understanding of the genesis of tornadoes and downbursts within thunderstorms, and greater resolution in global climate models. To improve coping strategies, forest scientists can contribute by giving more attention to how various silvicultural actions influence stand and tree vulnerability. Finally, increased focus on the dynamics of forest recovery and regrowth may suggest management actions that can facilitate desired objectives after one of these unpredictable wind disturbances.

  14. Variable effects of climate on forest growth in relation to climate extremes, disturbance, and forest dynamics.

    Science.gov (United States)

    Itter, Malcolm S; Finley, Andrew O; D'Amato, Anthony W; Foster, Jane R; Bradford, John B

    2017-06-01

    Changes in the frequency, duration, and severity of climate extremes are forecast to occur under global climate change. The impacts of climate extremes on forest productivity and health remain difficult to predict due to potential interactions with disturbance events and forest dynamics-changes in forest stand composition, density, size and age structure over time. Such interactions may lead to non-linear forest growth responses to climate involving thresholds and lag effects. Understanding how forest dynamics influence growth responses to climate is particularly important given stand structure and composition can be modified through management to increase forest resistance and resilience to climate change. To inform such adaptive management, we develop a hierarchical Bayesian state space model in which climate effects on tree growth are allowed to vary over time and in relation to past climate extremes, disturbance events, and forest dynamics. The model is an important step toward integrating disturbance and forest dynamics into predictions of forest growth responses to climate extremes. We apply the model to a dendrochronology data set from forest stands of varying composition, structure, and development stage in northeastern Minnesota that have experienced extreme climate years and forest tent caterpillar defoliation events. Mean forest growth was most sensitive to water balance variables representing climatic water deficit. Forest growth responses to water deficit were partitioned into responses driven by climatic threshold exceedances and interactions with insect defoliation. Forest growth was both resistant and resilient to climate extremes with the majority of forest growth responses occurring after multiple climatic threshold exceedances across seasons and years. Interactions between climate and disturbance were observed in a subset of years with insect defoliation increasing forest growth sensitivity to water availability. Forest growth was particularly

  15. Know your limits? Climate extremes impact the range of Scots pine in unexpected places.

    Science.gov (United States)

    Julio Camarero, J; Gazol, Antonio; Sancho-Benages, Santiago; Sangüesa-Barreda, Gabriel

    2015-11-01

    Although extreme climatic events such as drought are known to modify forest dynamics by triggering tree dieback, the impact of extreme cold events, especially at the low-latitude margin ('rear edge') of species distributional ranges, has received little attention. The aim of this study was to examine the impact of one such extreme cold event on a population of Scots pine (Pinus sylvestris) along the species' European southern rear-edge range limit and to determine how such events can be incorporated into species distribution models (SDMs). A combination of dendrochronology and field observation was used to quantify how an extreme cold event in 2001 in eastern Spain affected growth, needle loss and mortality of Scots pine. Long-term European climatic data sets were used to contextualize the severity of the 2001 event, and an SDM for Scots pine in Europe was used to predict climatic range limits. The 2001 winter reached record minimum temperatures (equivalent to the maximum European-wide diurnal ranges) and, for trees already stressed by a preceding dry summer and autumn, this caused dieback and large-scale mortality. Needle loss and mortality were particularly evident in south-facing sites, where post-event recovery was greatly reduced. The SDM predicted European Scots pine distribution mainly on the basis of responses to maximum and minimum monthly temperatures, but in comparison with this the observed effects of the 2001 cold event at the southerly edge of the range limit were unforeseen. The results suggest that in order to better forecast how anthropogenic climate change might affect future forest distributions, distribution modelling techniques such as SDMs must incorporate climatic extremes. For Scots pine, this study shows that the effects of cold extremes should be included across the entire distribution margin, including the southern 'rear edge', in order to avoid biased predictions based solely on warmer climatic scenarios. © The Author 2015. Published by

  16. Wildfires in Siberian Mountain Forest

    Science.gov (United States)

    Kharuk, V.; Ponomarev, E. I.; Antamoshkina, O.

    2017-12-01

    The annual burned area in Russia was estimated as 0.55 to 20 Mha with >70% occurred in Siberia. We analyzed Siberian wildfires distribution with respect to elevation, slope steepness and exposure. In addition, wildfires temporal dynamic and latitudinal range were analyzed. We used daily thermal anomalies derived from NOAA/AVHRR and Terra/MODIS satellites (1990-2016). Fire return intervals were (FRI) calculated based on the dendrochronology analysis of samples taken from trees with burn marks. Spatial distribution of wildfires dependent on topo features: relative burned area increase with elevation increase (ca. 1100 m), switching to following decrease. The wildfires frequency exponentially decreased within lowlands - highlands transition. Burned area is increasing with slope steepness increase (up to 5-10°). Fire return intervals (FRI) on the southfacing slopes are about 30% longer than on the north facing. Wildfire re-occurrence is decreasing exponentially: 90% of burns were caused by single fires, 8.5% by double fires, 1% burned three times, and on about 0.05% territory wildfires occurred four times (observed period: 75 yr.). Wildfires area and number, as well as FRI, also dependent on latitude: relative burned area increasing exponentially in norward direction, whereas relative fire number is exponentially decreasing. FRI increases in the northward direction: from 80 years at 62°N to 200 years at the Arctic Circle, and to 300 years at the northern limit of closed forests ( 71+°N). Fire frequency, fire danger period and FRI are strongly correlated with incoming solar radiation (r = 0.81 - 0.95). In 21-s century, a positive trend of wildfires number and area observed in mountain areas in all Siberia. Thus, burned area and number of fires in Siberia are significantly increased since 1990th (R2 =0.47, R2 =0.69, respectively), and that increase correlated with air temperatures and climate aridity increases. However, wildfires are essential for supporting fire

  17. A Multi-Faceted Debris-Flood Hazard Assessment for Cougar Creek, Alberta, Canada

    Directory of Open Access Journals (Sweden)

    Matthias Jakob

    2017-01-01

    Full Text Available A destructive debris flood occurred between 19 and 21 June 2013 on Cougar Creek, located in Canmore, Alberta. Cougar Creek fan is likely the most densely developed alluvial fan in Canada. While no lives were lost, the event resulted in approximately $40 M of damage and closed both the Trans-Canada Highway (Highway 1 and the Canadian Pacific Railway line for a period of several days. The debris flood triggered a comprehensive hazard assessment which is the focus of this paper. Debris-flood frequencies and magnitudes are determined by combining several quantitative methods including photogrammetry, dendrochronology, radiometric dating, test pit logging, empirical relationships between rainfall volumes and sediment volumes, and landslide dam outburst flood modeling. The data analysis suggests that three distinct process types act in the watershed. The most frequent process is normal or “clearwater” floods. Less frequent but more damaging are debris floods during which excessive amounts of bedload are transported on the fan, typically associated with rapid and extensive bank erosion and channel infilling and widening. The third and most destructive process is interpreted to be landslide dam outbreak floods. This event type is estimated to occur at return periods exceeding 300 years. Using a cumulative magnitude frequency technique, the data for conventional debris floods were plotted up to the 100–300s year return period. A peak-over-threshold approach was used for landslide dam outbreak floods occurring at return periods exceeding 300 years, as not all such events were identified during test trenching. Hydrographs for 6 return period classes were approximated by using the estimated peak discharges and fitting the hydrograph shape to integrate to the debris flood volumes as determined from the frequency-magnitude relationship. The fan volume was calculated and compared with the integrated frequency-magnitude curve to check of the validity of

  18. Limited evidence for CO2 -related growth enhancement in northern Rocky Mountain lodgepole pine populations across climate gradients.

    Science.gov (United States)

    Reed, Charlotte C; Ballantyne, Ashley P; Cooper, Leila Annie; Sala, Anna

    2018-04-15

    Forests sequester large amounts of carbon annually and are integral in buffering against effects of global change. Increasing atmospheric CO 2 may enhance photosynthesis and/or decrease stomatal conductance (g s ) thereby enhancing intrinsic water-use efficiency (iWUE), having potential indirect and direct benefits to tree growth. While increasing iWUE has been observed in most trees globally, enhanced growth is not ubiquitous, possibly due to concurrent climatic constraints on growth. To investigate our incomplete understanding of interactions between climate and CO 2 and their impacts on tree physiology and growth, we used an environmental gradient approach. We combined dendrochronology with carbon isotope analysis (δ 13 C) to assess the covariation of basal area increment (BAI) and iWUE over time in lodgepole pine. Trees were sampled at 18 sites spanning two climatically distinct elevation transects on the lee and windward sides of the Continental Divide, encompassing the majority of lodgepole pine's northern Rocky Mountain elevational range. We analyzed BAI and iWUE from 1950 to 2015, and explored correlations with monthly climate variables. As expected, iWUE increased at all sites. However, concurrent growth trends depended on site climatic water deficit (CWD). Significant growth increases occurred only at the driest sites, where increases in iWUE were strongest, while growth decreases were greatest at sites where CWD has been historically lowest. Late summer drought of the previous year negatively affected growth across sites. These results suggest that increasing iWUE, if strong enough, may indirectly benefit growth at drier sites by effectively extending the growing season via reductions in g s . Strong growth decreases at high elevation windward sites may reflect increasing water stress as a result of decreasing snowpack, which was not offset by greater iWUE. Our results imply that increasing iWUE driven by decreasing g s may benefit tree growth in

  19. Trace metal concentrations in Posidonia oceanica of North Corsica (northwestern Mediterranean Sea: use as a biological monitor?

    Directory of Open Access Journals (Sweden)

    Gosselin Marc

    2006-09-01

    Full Text Available Abstract Background Within semi-closed areas like the Mediterranean Sea, anthropic wastes tend to concentrate in the environment. Metals, in particular, are known to persist in the environment and can affect human health due to accumulation in the food chain. The seagrass Posidonia oceanica, widely found in Mediterranean coastal waters, has been chosen as a "sentinel" to quantify the distribution of such pollutants within the marine environment. Using a technique similar to dendrochronology in trees, it can act as an indicator of pollutant levels over a timeframe of several months to years. In the present study, we measured and compared the levels of eight trace metals (Cr, Ni, Cu, Zn, As, Se, Cd, and Pb in sheaths dated by lepidochronology and in leaves of shoots sampled from P. oceanica meadows collected from six offshore sites in northern Corsica between 1988 and 2004; in the aim to determine 1 the spatial and 2 temporal variations of these metals in these areas and 3 to compared these two types of tissues. Results We found low trace metal concentrations with no increase over the last decade, confirming the potential use of Corsican seagrass beds as reference sites for the Mediterranean Sea. Temporal trends of trace metal concentrations in sheaths were not significant for Cr, Ni, Cu, As or Se, but Zn, Cd, and Pb levels decreased, probably due to the reduced anthropic use of these metals. Similar temporal trends between Cu levels in leaves (living tissue and in sheaths (dead tissue demonstrated that lepidochronology linked with Cu monitoring is effective for surveying the temporal variability of this metal. Conclusion Leaves of P. oceanica can give an indication of the metal concentration in the environment over a short time period (months with good accuracy. On the contrary, sheaths, which gave an indication of changes over long time periods (decades, seem to be less sensitive to variations in the metal concentration in the environment

  20. Primeros resultados para la reconstrucción dendroclimática de Canarias

    Directory of Open Access Journals (Sweden)

    Carlos L. Santana Jubells

    2013-11-01

    Full Text Available La aplicación de la Dendrocronología a poblaciones canarias de Pinus canariensis Smith, taxón que hasta el momento no había sido objetivo de esta ciencia, y la obtención de los primeros resultados positivos en la comparación cruzada de series de crecimiento, abren las puertas a una reconstrucción de las variables climáticas precipitación y temperatura del pasado en el Archipiélago. Entre las muchas aplicaciones que es posible derivar de dicha reconstrucción, centra el interés de la Prehistoria el conocimiento, desde una perspectiva diacrónica, de una parte fundamental del entorno ecológico en el que se desarrollan de las poblaciones pehispánicas de Canarias, como vía válida para enriquecer la interpretación de ciertas transformaciones culturales. Los cambios que se operan en la isla de La Palma en el tránsito entre las fases cerámica III y IV, pueden ser interpretados como claro exponente de la intima relación que existe entre el desarrollo de los sistemas culturales y las alteraciones de su marco medioambiental.The application of Dendrochronology to populations of Pinus canariensis Smith from the Canary Islands -species never studied by this science before- and the first positive results in cross-dating of tree-ring series, are achievements that lead to the future reconstruction of the past climatic variables precipitations and temperatures in the Canaries. Among the many applications derived from this climatic reconstruction, the knowledge from a dicahronic perspective if a fundamental piece of the ecological environment in wich the Canarian prehispanic peoples developed will provide Prehistory with a powerful tool to enrich the interpretation of certain cultural phenomena. The changes that took place in La Palma in the transition between the ceramic phases II and IV, can be interpreted as a clear example of the close relationship existing between development of cultural systems and modifications in its environmental frame.