Relating P-band AIRSAR backscatter to forest stand parameters

Science.gov (United States)

Wang, Yong; Melack, John M.; Davis, Frank W.; Kasischke, Eric S.; Christensen, Norman L., Jr.

1993-01-01

As part of research on forest ecosystems, the Jet Propulsion Laboratory (JPL) and collaborating research teams have conducted multi-season airborne synthetic aperture radar (AIRSAR) experiments in three forest ecosystems including temperate pine forest (Duke, Forest, North Carolina), boreal forest (Bonanza Creek Experimental Forest, Alaska), and northern mixed hardwood-conifer forest (Michigan Biological Station, Michigan). The major research goals were to improve understanding of the relationships between radar backscatter and phenological variables (e.g. stand density, tree size, etc.), to improve radar backscatter models of tree canopy properties, and to develop a radar-based scheme for monitoring forest phenological changes. In September 1989, AIRSAR backscatter data were acquired over the Duke Forest. As the aboveground biomass of the loblolly pine forest stands at Duke Forest increased, the SAR backscatter at C-, L-, and P-bands increased and saturated at different biomass levels for the C-band, L-band, and P-band data. We only use the P-band backscatter data and ground measurements here to study the relationships between the backscatter and stand density, the backscatter and mean trunk dbh (diameter at breast height) of trees in the stands, and the backscatter and stand basal area.

Dynamics of Coarse Woody Debris Characteristics in the Qinling Mountain Forests in China

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Jie Yuan

2017-10-01

Full Text Available Coarse woody debris (CWD is an essential component in defining the structure and function of forest ecosystems. Long-term dynamics of CWD characteristics not only affect the release rates of chemical elements from CWD, but also the species diversity of inhabiting plants, animals, insects, and microorganisms as well as the overall health of ecosystems. However, few quantitative studies have been done on the long-term dynamics of CWD characteristics in forest ecosystems in China. In this study, we conducted nine tree censuses between 1996 and 2016 at the Huoditang Experimental Forest in the Qinling Mountains of China. We quantified forest biomass including CWD and CWD characteristics such as decay states and diameter classes during this period and correlated with stand, site, and climatic variables. The forest biomass was dominated by live tree biomass (88%; followed by CWD mass (6%–10%. Understory biomass contributed only a small portion (1%–4% of the overall biomass. Significant differences in average annual increment of CWD mass were found among forest stands of different species (p < 0.0001. Forest biomass, stand age, forest type, aspect, slope, stand density, annual average temperature, and precipitation were all significantly correlated with CWD mass (p < 0.05, with forest type exhibiting the strongest correlation (r2 = 0.8256. Over time, the annual mass of different CWD characteristics increased linearly from 1996–2016 across all forest types. Our study revealed that forest biomass, including CWD characteristics, varied by forest type. Stand and site characteristics (forest biomass, forest type, aspect, slope and stand density along with temperature and precipitation played a major role in the dynamics of CWD in the studied forest ecosystems.

A forest simulation approach using weighted Voronoi diagrams. An application to Mediterranean fir Abies pinsapo Boiss stands

Energy Technology Data Exchange (ETDEWEB)

Abellanas, B.; Abellanas, M.; Pommerening, A.; Lodares, D.; Cuadros, S.

2016-07-01

Aim of the study. a) To present a new version of the forest simulator Vorest, an individual-based spatially explicit model that uses weighted Voronoi diagrams to simulate the natural dynamics of forest stands with closed canopies. b) To apply the model to the current dynamics of a Grazalema pinsapo stand to identify the nature of its competition regime and the stagnation risks it is currently facing. Area of study: Sierra del Pinar de Grazalema (S Spain) Material and methods: Two large plots representative of Grazalema pinsapo stands were used to fit and validate the model (plus 6 accesory plots to increase the availability of mortality data). Two inventories were carried out in 1998 and 2007 producing tree size and location data. We developed a forest simulator based on three submodels: growth, competition and mortality. The model was fitted, evaluated and validated for Grazalema plots. The simulation outputs were used to infer the expected evolution of structural diversity of forest stands. Main results: Vorest has proved to be a good tool for simulating dynamics of natural closed stands. The application to Grazalema pinsapo stands has allowed assessing the nature of the main processes that are driving its development pathway. We have found that the prevailing size-asymmetric competition dominates the self-thinning process in small-sized trees. At the same time, there is an active tree-size differentiation process. Research highlights: Vorest has proved to be a good tool for simulating natural stands with closed canopies. The Grazalema pinsapo stand under consideration is currently undergoing a natural process of differentiation, avoiding long-term stagnation. (Author)

An analytical model of stand dynamics as a function of tree growth, mortality and recruitment: the shade tolerance-stand structure hypothesis revisited.

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Zavala, Miguel A; Angulo, Oscar; Bravo de la Parra, Rafael; López-Marcos, Juan C

2007-02-07

Light competition and interspecific differences in shade tolerance are considered key determinants of forest stand structure and dynamics. Specifically two main stand diameter distribution types as a function of shade tolerance have been proposed based on empirical observations. All-aged stands of shade tolerant species tend to have steeply descending, monotonic diameter distributions (inverse J-shaped curves). Shade intolerant species in contrast typically exhibit normal (unimodal) tree diameter distributions due to high mortality rates of smaller suppressed trees. In this study we explore the generality of this hypothesis which implies a causal relationship between light competition or shade tolerance and stand structure. For this purpose we formulate a partial differential equation system of stand dynamics as a function of individual tree growth, recruitment and mortality which allows us to explore possible individual-based mechanisms--e.g. light competition-underlying observed patterns of stand structure--e.g. unimodal or inverse J-shaped equilibrium diameter curves. We find that contrary to expectations interspecific differences in growth patterns can result alone in any of the two diameter distributions types observed in the field. In particular, slow growing species can present unimodal equilibrium curves even in the absence of light competition. Moreover, light competition and shade intolerance evaluated both at the tree growth and mortality stages did not have a significant impact on stand structure that tended to converge systematically towards an inverse J-shaped curves for most tree growth scenarios. Realistic transient stand dynamics for even aged stands of shade intolerant species (unimodal curves) were only obtained when recruitment was completely suppressed, providing further evidence on the critical role played by juvenile stages of tree development (e.g. the sampling stage) on final forest structure and composition. The results also point out the

Forest dynamics [version 1; referees: 2 approved

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Lee Frelich

2016-02-01

Full Text Available Forest dynamics encompass changes in stand structure, species composition, and species interactions with disturbance and environment over a range of spatial and temporal scales. For convenience, spatial scale is defined as individual tree, neighborhood, stand, and landscape. Whether a given canopy-leveling disturbance will initiate a sequence of development in structure with little change in composition or initiate an episode of succession depends on a match or mismatch, respectively, with traits of the dominant tree species that allow the species to survive disturbance. When these match, certain species-disturbance type combinations lock in a pattern of stand and landscape dynamics that can persist for several generations of trees; thus, dominant tree species regulate, as well as respond to, disturbance. A complex interaction among tree species, neighborhood effects, disturbance type and severity, landform, and soils determines how stands of differing composition form and the mosaic of stands that compose the landscape. Neighborhood effects (e.g., serotinous seed rain, sprouting, shading, leaf-litter chemistry, and leaf-litter physical properties operate at small spatial extents of the individual tree and its neighbors but play a central role in forest dynamics by contributing to patch formation at stand scales and dynamics of the entire landscape. Dominance by tree species with neutral to negative neighborhood effects leads to unstable landscape dynamics in disturbance-prone regions, wherein most stands are undergoing succession; stability can only occur under very low-severity disturbance regimes. Dominance by species with positive effects leads to stable landscape dynamics wherein only a small proportion of stands undergo succession at any one time. Positive neighborhood effects are common in temperate and boreal zones, whereas negative effects are more common in tropical climates. Landscapes with positive dynamics have alternate categories

Effect of different tree mortality patterns on stand development in the forest model SIBYLA

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Trombik Jiří

2016-09-01

Full Text Available Forest mortality critically affects stand structure and the quality of ecosystem services provided by forests. Spruce bark beetle (Ips typographus generates rather complex infestation and mortality patterns, and implementation of such patterns in forest models is challenging. We present here the procedure, which allows to simulate the bark beetle-related tree mortality in the forest dynamics model Sibyla. We explored how sensitive various production and stand structure indicators are to tree mortality patterns, which can be generated by bark beetles. We compared the simulation outputs for three unmanaged forest stands with 40, 70 and 100% proportion of spruce as affected by the disturbance-related mortality that occurred in a random pattern and in a patchy pattern. The used tree species and age class-specific mortality rates were derived from the disturbance-related mortality records from Slovakia. The proposed algorithm was developed in the SQLite using the Python language, and the algorithm allowed us to define the degree of spatial clustering of dead trees ranging from a random distribution to a completely clustered distribution; a number of trees that died in either mode is set to remain equal. We found significant differences between the long-term developments of the three investigated forest stands, but we found very little effect of the tested mortality modes on stand increment, tree species composition and diversity, and tree size diversity. Hence, our hypothesis that the different pattern of dead trees emergence should affect the competitive interactions between trees and regeneration, and thus affect selected productivity and stand structure indicators was not confirmed.

ESTIMATION OF STAND HEIGHT AND FOREST VOLUME USING HIGH RESOLUTION STEREO PHOTOGRAPHY AND FOREST TYPE MAP

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K. M. Kim

2016-06-01

Full Text Available Traditional field methods for measuring tree heights are often too costly and time consuming. An alternative remote sensing approach is to measure tree heights from digital stereo photographs which is more practical for forest managers and less expensive than LiDAR or synthetic aperture radar. This work proposes an estimation of stand height and forest volume(m3/ha using normalized digital surface model (nDSM from high resolution stereo photography (25cm resolution and forest type map. The study area was located in Mt. Maehwa model forest in Hong Chun-Gun, South Korea. The forest type map has four attributes such as major species, age class, DBH class and crown density class by stand. Overlapping aerial photos were taken in September 2013 and digital surface model (DSM was created by photogrammetric methods(aerial triangulation, digital image matching. Then, digital terrain model (DTM was created by filtering DSM and subtracted DTM from DSM pixel by pixel, resulting in nDSM which represents object heights (buildings, trees, etc.. Two independent variables from nDSM were used to estimate forest stand volume: crown density (% and stand height (m. First, crown density was calculated using canopy segmentation method considering live crown ratio. Next, stand height was produced by averaging individual tree heights in a stand using Esri’s ArcGIS and the USDA Forest Service’s FUSION software. Finally, stand volume was estimated and mapped using aerial photo stand volume equations by species which have two independent variables, crown density and stand height. South Korea has a historical imagery archive which can show forest change in 40 years of successful forest rehabilitation. For a future study, forest volume change map (1970s–present will be produced using this stand volume estimation method and a historical imagery archive.

Temperate and boreal old-growth forests: how do their growth dynamics and biodiversity differ from young stands and managed forests?

NARCIS (Netherlands)

Schulze, E.D.; Hessenmoeller, D; Knohl, A.; Luyssaert, S; Boerner, A; Grace, J.

2009-01-01

This chapter investigates biomass, net primary productivity (NPP), and net ecosystem productivity (NEP) of boreal and temperate forest ecosystems in relation to stand density and age. Forests may accumulate woody biomass at constant rate for centuries and there is little evidence of an age-related

The role of stand history in assessing forest impacts

Science.gov (United States)

Dale, V.H.; Doyle, T.W.

1987-01-01

Air pollution, harvesting practices, and natural disturbances can affect the growth of trees and forest development. To make predictions about anthropogenic impacts on forests, we need to understand how these factors affect tree growth. In this study the effect of disturbance history on tree growth and stand structure was examined by using a computer model of forest development. The model was run under the climatic conditions of east Tennessee, USA, and the results compared to stand structure and tree growth data from a yellow poplar-white oak forest. Basal area growth and forest biomass were more accurately projected when rough approximations of the thinning and fire history typical of the measured plots were included in the simulation model. Stand history can influence tree growth rates and forest structure and should be included in any attempt to assess forest impacts.

Forest evaporation models: Relationships between stand growth and evaporation

CSIR Research Space (South Africa)

Le Maitre, David C

1997-06-01

Full Text Available The relationships between forest stand structure, growth and evaporation were analysed to determine whether forest evaporation can be estimated from stand growth data. This approach permits rapid assessment of the potential impacts of afforestation...

Stand model for upland forests of Southern Arkansas

Energy Technology Data Exchange (ETDEWEB)

Mielke, D.L.; Shugart, H.H.; West, D.C.

1978-06-01

A forest stand growth and composition simulator (FORAR) was developed by modifying a stand growth model by Shugart and West (1977). FORAR is a functional stand model which used ecological parameters to relate individual tree growth to environment rather than using Markov probability matrices or differential equations to determine single tree or species replacement rates. FORAR simulated tree growth and species composition of upland forests of Union County, Ark., by considering 33 tree species on a /sup 1///sub 12/ ha circular plot.

Simulation of Forest Cover Dynamics for Eastern Eurasian Boreal Forests

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Shugart, H. H.; Yan, X.; Zhang, N.; Isaev, A. S.; Shuman, J. K.

2006-12-01

We are developing and testing a boreal zone forest dynamics model capable of simulating the forest cover dynamics of the Eurasian boreal forest, a major biospheric ecosystem with potentially large roles in the planetary carbon cycle and in the feedback between terrestrial surface and the atmosphere. In appreciating the role of this region in the coupling between atmosphere and terrestrial surface, on must understand the interactions between CO2 source/sink relationships (associated with growing or clearing forests) and the albedo effects (from changes in terrestrial surface cover). There is some evidence that in the Eurasian Boreal zone, the Carbon budget effects from forest change may oppose the albedo changes. This creates complex feedbacks between surface and atmosphere and motivates the need for a forest dynamics model that simultaneous represents forest vegetation and carbon storage and release. A forest dynamics model applied to Eastern Eurasia, FAREAST, has been tested using three types of information: 1. Direct species composition comparisons between simulated and observed mature forests at the same locations; 2. Forest type comparisons between simulated and observed forests along altitudinal gradients of several different mountains; 3. Comparison with forest stands in different succession stages of simulated forests. Model comparisons with independent data indicate the FAREAST model is capable of representing many of the broad features of the forests of Northeastern China. After model validation in the Northeast China region, model applications were developed for the forests of the Russian Far East. Continental-scale forest cover can be simulated to a relatively realistic degree using a forest gap model with standard representations of individual-plant processes. It appears that such a model, validated relatively locally in this case, in Northeastern China, can then be applied over a much larger region and under conditions of climatic change.

Spatial analysis of longleaf pine stand dynamics after 60 years of management

Science.gov (United States)

John C. Gilbert; John S. Kush; Rebecca J. Barlow

2012-01-01

There are still many questions and misconceptions about the stand dynamics of naturally-regenerated longleaf pine (Pinus palustris Mill.). Since 1948, the “Farm Forty,” a forty-acre tract located on the USDA Forest Service Escambia Experimental Forest near Brewton, Alabama, has been managed to create high quality wood products, to successfully...

Minnesota DNR Forest Stand Inventory Version 2

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Minnesota Department of Natural Resources — This layer is a digital inventory of individual forest stands. The data is collected by DNR Foresters in each DNR Forestry Administrative Area, and is updated on a...

Relationship of Tree Stand Heterogeneity and Forest Naturalness

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BARTHA, Dénes

2006-01-01

Full Text Available The aim of our study was to investigate if compositional (tree species richness andstructural (vertical structure, age-structure, patterns of canopy closure heterogeneity of the canopylayer is related to individual naturalness criteria and to overall forest naturalness at the stand scale. Thenaturalness values of the assessed criteria (tree species composition, tree stand structure, speciescomposition and structure of shrub layer and forest floor vegetation, dead wood, effects of game, sitecharacteristics showed similar behaviour when groups of stands with different heterogeneity werecompared, regardless of the studied aspect of canopy heterogeneity. The greatest difference was foundfor criteria describing the canopy layer. Composition and structure of canopy layer, dead wood andtotal naturalness of the stand differed significantly among the stand groups showing consistentlyhigher values from homogeneous to the most heterogeneous group. Naturalness of the compositionand structure of the shrub layer is slightly but significantly higher in stands with heterogeneous canopylayer. Regarding other criteria, significant differences were found only between the homogeneous andthe most heterogeneous groups, while groups with intermediate level of heterogeneity did not differsignificantly from one extreme. However, the criterion describing effects of game got lowernaturalness values in more heterogeneous stands. Naturalness of site characteristics did not differsignificantly among the groups except for when stands were grouped based on pattern of canopyclosure. From the practical viewpoint it is shown that purposeful forestry operations affecting thecanopy layer cause changes in compositional and structural characteristics of other layers as well as inoverall stand scale forest naturalness.

The long-term hydrological effect of forest stands on the stability of slopes

Science.gov (United States)

Bogaard, T. A.; Meng, W.; van Beek, L. P. H.

2012-04-01

used in a spatially distributed, physical-based, dynamical model to simulate the hydrology and resulting stability for a catchment on a daily scale. The results can be used to identify end members of the hydrological influence of forests on slope stability and the typical variations in stability associated with the various growth stages. They indicate that the influence of forest stand age on the water consumption can be significant and has clear consequences for the antecedent soil moisture condition within a slope and thus on the potential for slope destabilization. The outcome should help to understand the long-term impact of vegetation on slope hydrology and define sustainable and reliable management strategies at the scale of forest stands. Keywords: slope stability, hydrology, vegetation, long-tem effect

Stand Dynamics and Biomass Increment in a Lucidophyllous Forest over a 28-Year Period in Central Japan

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Siyu Chen

2017-10-01

Full Text Available Secondary lucidophyllous forest is one of the dominant forests in human-dominated subtropical/warm-temperate regions in East Asia. There were few direct monitoring techniques to elucidate the following hypotheses: (a self-thinning may govern the stand development process and (b wood production decline can be observed during secondary succession in a lucidophyllous forest. We conducted a long-term study at a permanent plot in central Japan, since 1989. The forest consists mainly of Castanopsis cuspidata in a canopy layer, Cleyera japonica, and Eurya japonica in a subtree layer. During the 28-year period, the basal area of the stand significantly increased due to the growth of C. cuspidata, from 29.18 ± 1.84 (87.8% of total to 38.71 ± 2.22 m2 ha−1 (91.9%, while the stem density of C. cuspidata significantly decreased from 666 ± 13 to 404 ± 10 stems ha−1 in proportion to accumulating biomass (117.8 to 166.6 ton ha−1. The annual woody net primary production ranged from 2.40 ± 0.13 to 3.93 ± 0.33 ton ha−1 year−1 as a nearly 70-year-old forest. There was no age-related decline of woody net primary production (NPP was found during secondary succession, and the growth of individual tree still increased when the self-thinning process governed the stand.

DRAINMOD-FOREST: Integrated Modeling of Hydrology, Soil Carbon and Nitrogen Dynamics, and Plant Growth for Drained Forests.

Science.gov (United States)

Tian, Shiying; Youssef, Mohamed A; Skaggs, R Wayne; Amatya, Devendra M; Chescheir, G M

2012-01-01

We present a hybrid and stand-level forest ecosystem model, DRAINMOD-FOREST, for simulating the hydrology, carbon (C) and nitrogen (N) dynamics, and tree growth for drained forest lands under common silvicultural practices. The model was developed by linking DRAINMOD, the hydrological model, and DRAINMOD-N II, the soil C and N dynamics model, to a forest growth model, which was adapted mainly from the 3-PG model. The forest growth model estimates net primary production, C allocation, and litterfall using physiology-based methods regulated by air temperature, water deficit, stand age, and soil N conditions. The performance of the newly developed DRAINMOD-FOREST model was evaluated using a long-term (21-yr) data set collected from an artificially drained loblolly pine ( L.) plantation in eastern North Carolina, USA. Results indicated that the DRAINMOD-FOREST accurately predicted annual, monthly, and daily drainage, as indicated by Nash-Sutcliffe coefficients of 0.93, 0.87, and 0.75, respectively. The model also predicted annual net primary productivity and dynamics of leaf area index reasonably well. Predicted temporal changes in the organic matter pool on the forest floor and in forest soil were reasonable compared to published literature. Both predicted annual and monthly nitrate export were in good agreement with field measurements, as indicated by Nash-Sutcliffe coefficients above 0.89 and 0.79 for annual and monthly predictions, respectively. This application of DRAINMOD-FOREST demonstrated its capability for predicting hydrology and C and N dynamics in drained forests under limited silvicultural practices. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

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

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

2018-03-11

assessing stand-level growth response to climate, we provide an alternative perspective on climate-growth relationships of forests, improving our understanding of forest growth dynamics under a fluctuating climate. © 2018 John Wiley & Sons Ltd.

Occurrence of termites (Isoptera on living and standing dead trees in a tropical dry forest in Mexico

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Nancy Calderón-Cortés

2018-05-01

Full Text Available Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60–98% of standing dead trees and 23–59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057–0.066 trees/m2 than in riparian forests (0.022 and 0.027 trees/m2, even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01–0.09 trees/m2 than in larger class sizes (0–0.02 trees/m2. Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil.

Occurrence of termites (Isoptera) on living and standing dead trees in a tropical dry forest in Mexico.

Science.gov (United States)

Calderón-Cortés, Nancy; Escalera-Vázquez, Luis H; Oyama, Ken

2018-01-01

Termites play a key role as ecosystem engineers in numerous ecological processes though their role in the dynamics of wood degradation in tropical dry forests, particularly at the level of the crown canopy, has been little studied. In this study, we analysed the occurrence of termites in the forest canopy by evaluating the density and proportion of living and standing dead trees associated with termites in deciduous and riparian habitats of the tropical dry forest in Chamela, Mexico. The results indicated that 60-98% of standing dead trees and 23-59% of living trees in Chamela were associated with termites. In particular, we found that the density of standing dead trees was higher in deciduous forests (0.057-0.066 trees/m 2 ) than in riparian forests (0.022 and 0.027 trees/m 2 ), even though the proportion of trees was not significantly different among habitats. Additionally, we found a higher density of trees associated with termites in trees of smaller size classes (0.01-0.09 trees/m 2 ) than in larger class sizes (0-0.02 trees/m 2 ). Interestingly, 72% of variation in the density of trees associated with termites is explained by the density of standing dead trees. Overall, these results indicate that standing dead tree availability might be the main factor regulating termite populations in Chamela forest and suggest that termites could play a key role in the decomposition of above-ground dead wood, mediating the incorporation of suspended and standing dead wood into the soil.

Tropical forest biomass estimation from truncated stand tables.

Science.gov (United States)

A. J. R. Gillespie; S. Brown; A. E. Lugo

1992-01-01

Total aboveground forest biomass may be estimated through a variety of techniques based on commercial inventory stand and stock tables. Stand and stock tables from tropical countries commonly omit trees bellow a certain commercial limit.

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

Variation in carbon storage and its distribution by stand age and forest type in boreal and temperate forests in northeastern China.

Science.gov (United States)

Wei, Yawei; Li, Maihe; Chen, Hua; Lewis, Bernard J; Yu, Dapao; Zhou, Li; Zhou, Wangming; Fang, Xiangmin; Zhao, Wei; Dai, Limin

2013-01-01

The northeastern forest region of China is an important component of total temperate and boreal forests in the northern hemisphere. But how carbon (C) pool size and distribution varies among tree, understory, forest floor and soil components, and across stand ages remains unclear. To address this knowledge gap, we selected three major temperate and two major boreal forest types in northeastern (NE) China. Within both forest zones, we focused on four stand age classes (young, mid-aged, mature and over-mature). Results showed that total C storage was greater in temperate than in boreal forests, and greater in older than in younger stands. Tree biomass C was the main C component, and its contribution to the total forest C storage increased with increasing stand age. It ranged from 27.7% in young to 62.8% in over-mature stands in boreal forests and from 26.5% in young to 72.8% in over-mature stands in temperate forests. Results from both forest zones thus confirm the large biomass C storage capacity of old-growth forests. Tree biomass C was influenced by forest zone, stand age, and forest type. Soil C contribution to total forest C storage ranged from 62.5% in young to 30.1% in over-mature stands in boreal and from 70.1% in young to 26.0% in over-mature in temperate forests. Thus soil C storage is a major C pool in forests of NE China. On the other hand, understory and forest floor C jointly contained less than 13% and forests respectively, and thus play a minor role in total forest C storage in NE China.

Tree Regeneration Spatial Patterns in Ponderosa Pine Forests Following Stand-Replacing Fire: Influence of Topography and Neighbors

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Justin P. Ziegler

2017-10-01

Full Text Available Shifting fire regimes alter forest structure assembly in ponderosa pine forests and may produce structural heterogeneity following stand-replacing fire due, in part, to fine-scale variability in growing environments. We mapped tree regeneration in eighteen plots 11 to 15 years after stand-replacing fire in Colorado and South Dakota, USA. We used point pattern analyses to examine the spatial pattern of tree locations and heights as well as the influence of tree interactions and topography on tree patterns. In these sparse, early-seral forests, we found that all species were spatially aggregated, partly attributable to the influence of (1 aspect and slope on conifers; (2 topographic position on quaking aspen; and (3 interspecific attraction between ponderosa pine and other species. Specifically, tree interactions were related to finer-scale patterns whereas topographic effects influenced coarse-scale patterns. Spatial structures of heights revealed conspecific size hierarchies with taller trees in denser neighborhoods. Topography and heterospecific tree interactions had nominal effect on tree height spatial structure. Our results demonstrate how stand-replacing fires create heterogeneous forest structures and suggest that scale-dependent, and often facilitatory, rather than competitive, processes act on regenerating trees. These early-seral processes will establish potential pathways of stand development, affecting future forest dynamics and management options.

Incorporating stand level risk management options into forest decision support systems

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Kyle Eyvindson

2018-01-01

Full Text Available Aim of study: To examine methods of incorporating risk and uncertainty to stand level forest decisions. Area of study: A case study examines a small forest holding from Jönköping, Sweden. Material and methods: We incorporate empirically estimated uncertainty into the simulation through a Monte Carlo approach when simulating the forest stands for the next 100 years. For the iterations of the Monte Carlo approach, errors were incorporated into the input data which was simulated according to the Heureka decision support system. Both the Value at Risk and the Conditional Value at Risk of the net present value are evaluated for each simulated stand. Main results: Visual representation of the errors can be used to highlight which decision would be most beneficial dependent on the decision maker’s opinion of the forest inventory results. At a stand level, risk preferences can be rather easily incorporated into the current forest decision support software. Research highlights: Forest management operates under uncertainty and risk. Methods are available to describe this risk in an understandable fashion for the decision maker.

Estimating Stand Volume and Above-Ground Biomass of Urban Forests Using LiDAR

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Vincenzo Giannico

2016-04-01

Full Text Available Assessing forest stand conditions in urban and peri-urban areas is essential to support ecosystem service planning and management, as most of the ecosystem services provided are a consequence of forest stand characteristics. However, collecting data for assessing forest stand conditions is time consuming and labor intensive. A plausible approach for addressing this issue is to establish a relationship between in situ measurements of stand characteristics and data from airborne laser scanning (LiDAR. In this study we assessed forest stand volume and above-ground biomass (AGB in a broadleaved urban forest, using a combination of LiDAR-derived metrics, which takes the form of a forest allometric model. We tested various methods for extracting proxies of basal area (BA and mean stand height (H from the LiDAR point-cloud distribution and evaluated the performance of different models in estimating forest stand volume and AGB. The best predictors for both models were the scale parameters of the Weibull distribution of all returns (except the first (proxy of BA and the 95th percentile of the distribution of all first returns (proxy of H. The R2 were 0.81 (p < 0.01 for the stand volume model and 0.77 (p < 0.01 for the AGB model with a RMSE of 23.66 m3·ha−1 (23.3% and 19.59 Mg·ha−1 (23.9%, respectively. We found that a combination of two LiDAR-derived variables (i.e., proxy of BA and proxy of H, which take the form of a forest allometric model, can be used to estimate stand volume and above-ground biomass in broadleaved urban forest areas. Our results can be compared to other studies conducted using LiDAR in broadleaved forests with similar methods.

Relating demographic characteristics of a small mammal to remotely sensed forest-stand condition.

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Hania Lada

Full Text Available Many ecological systems around the world are changing rapidly in response to direct (land-use change and indirect (climate change human actions. We need tools to assess dynamically, and over appropriate management scales, condition of ecosystems and their responses to potential mitigation of pressures. Using a validated model, we determined whether stand condition of floodplain forests is related to densities of a small mammal (a carnivorous marsupial, Antechinus flavipes in 60,000 ha of extant river red gum (Eucalyptus camaldulensis forests in south-eastern Australia in 2004, 2005 and 2011. Stand condition was assessed remotely using models built from ground assessments of stand condition and satellite-derived reflectance. Other covariates, such as volumes of fallen timber, distances to floods, rainfall and life stages were included in the model. Trapping of animals was conducted at 272 plots (0.25 ha across the region. Densities of second-year females (i.e. females that had survived to a second breeding year and of second-year females with suckled teats (i.e. inferred to have been successful mothers were higher in stands with the highest condition. There was no evidence of a relationship with stand condition for males or all females. These outcomes show that remotely-sensed estimates of stand condition (here floodplain forests are relatable to some demographic characteristics of a small mammal species, and may provide useful information about the capacity of ecosystems to support animal populations. Over-regulation of large, lowland rivers has led to declines in many facets of floodplain function. If management of water resources continues as it has in recent decades, then our results suggest that there will be further deterioration in stand condition and a decreased capacity for female yellow-footed antechinuses to breed multiple times.

The Sylview graphical interface to the SYLVAN STAND STRUCTURE model with examples from southern bottomland hardwood forests

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David R. Larsen; Ian Scott

2010-01-01

In the field of forestry, the output of forest growth models provide a wealth of detailed information that can often be difficult to analyze and perceive due to presentation either as plain text summary tables or static stand visualizations. This paper describes the design and implementation of a cross-platform computer application for dynamic and interactive forest...

CERES: a model of forest stand biomass dynamics for predicting trace contaminant, nutrient, and water effects. I. Model description

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Dixon, K R; Luxmoore, R J; Begovich, C L

1978-06-01

CERES is a forest stand growth model which incorporates sugar transport in order to predict both short-term effects and long-term accumulation of trace contaminants and/or nutrients when coupled with the soil chemistry model (SCHEM), and models of solute uptake (DIFMAS and DRYADS) of the Unified Transport Model, UTM. An important feature of CERES is its ability to interface with the soil--plant--atmosphere water model (PROSPER) as a means of both predicting and studying the effects of plant water status on growth and solute transport. CERES considers the biomass dynamics of plants, standing dead and litter with plants divided into leaves, stems, roots, and fruits. The plant parts are divided further into sugar substrate, storage, and in the case of stems and roots, heartwood components. Each ecosystem omponent is described by a mass balance equation written as a first-order ordinary differential equation.

Relationships between net primary productivity and stand age for several forest types and their influence on China's carbon balance.

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Wang, Shaoqiang; Zhou, Lei; Chen, Jingming; Ju, Weimin; Feng, Xianfeng; Wu, Weixing

2011-06-01

Affected by natural and anthropogenic disturbances such as forest fires, insect-induced mortality and harvesting, forest stand age plays an important role in determining the distribution of carbon pools and fluxes in a variety of forest ecosystems. An improved understanding of the relationship between net primary productivity (NPP) and stand age (i.e., age-related increase and decline in forest productivity) is essential for the simulation and prediction of the global carbon cycle at annual, decadal, centurial, or even longer temporal scales. In this paper, we developed functions describing the relationship between national mean NPP and stand age using stand age information derived from forest inventory data and NPP simulated by the BEPS (Boreal Ecosystem Productivity Simulator) model in 2001. Due to differences in ecobiophysical characteristics of different forest types, NPP-age equations were developed for five typical forest ecosystems in China (deciduous needleleaf forest (DNF), evergreen needleleaf forest in tropic and subtropical zones (ENF-S), deciduous broadleaf forest (DBF), evergreen broadleaf forest (EBF), and mixed broadleaf forest (MBF)). For DNF, ENF-S, EBF, and MBF, changes in NPP with age were well fitted with a common non-linear function, with R(2) values equal to 0.90, 0.75, 0.66, and 0.67, respectively. In contrast, a second order polynomial was best suitable for simulating the change of NPP for DBF, with an R(2) value of 0.79. The timing and magnitude of the maximum NPP varied with forest types. DNF, EBF, and MBF reached the peak NPP at the age of 54, 40, and 32 years, respectively, while the NPP of ENF-S maximizes at the age of 13 years. The highest NPP of DBF appeared at 122 years. NPP was generally lower in older stands with the exception of DBF, and this particular finding runs counter to the paradigm of age-related decline in forest growth. Evaluation based on measurements of NPP and stand age at the plot-level demonstrates the reliability

Breeding avifauna of mature forest stands in the Borki Forest and its dynamics at the turn of the 21st century

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Rąkowski Grzegorz

2016-09-01

Full Text Available The composition and structure of the breeding bird community in the Borki Forest in north-eastern Poland were investigated during two separate periods: 1994–1996 and 2012–2014. Bird censuses were carried out in three plots located in mature oak-hornbeam, ash-alder and mixed coniferous forest stands. A standard combined mapping technique for estimating the number of breeding birds was applied. A total of 74 bird species bred at least once within any plot during 1994–1996 or 2012–2014. The structure of the bird assemblages on particular plots displayed a high degree of similarity, exceeding 75%, which means that they represent essentially the same bird community. However, the investigated assemblages have changed substantially over the 20 years. Both, the number of breeding bird species and the population densities on all plots, were much higher in 2012–2014 than in 1994–1996. The mean number of breeding species on all plots was over 50% higher in 2012–2014 than in 1994–1996, whereas the mean total density of breeding pairs increased by more than 60%. Total population densities on the plots increased as a result of an increase in population densities of individual bird species combined with an increase in the number of breeding species. Due to different rates of population growth for certain species, also the composition of dominating species group have changed. The observed changes in the avifauna of the Borki Forest were most probably due to an enrichment of the forest habitats structure, which was caused by natural factors, such as ageing of forest stands, forest succession and a change in water regime by beaver dams, as well as by forest management, including group felling within or in the vicinity of plots and uncovering of the forest edge.

Mapping of past stand-level forest disturbances and estimation of time since disturbance using simulated spaceborne LiDAR data

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Sanchez Lopez, N.; Hudak, A. T.; Boschetti, L.

2017-12-01

Explicit information on the location, the size or the time since disturbance (TSD) at the forest stand level complements field inventories, improves the monitoring of forest attributes and the estimation of biomass and carbon stocks. Even-aged stands display homogenous structural parameters that have often been used as a proxy of stand age. Consequently, performing object-oriented analysis on Light Detection and Ranging (LiDAR) data has potential to detect historical stand-replacing disturbances. Recent research has shown good results in the delineation of forest stands as well as in the prediction of disturbance occurrence and TSD using airborne LiDAR data. Nevertheless, the use of airborne LiDAR for systematic monitoring of forest stands is limited by the sporadic availability of data and its high cost compared to satellite instruments. NASA's forthcoming Global Ecosystem Dynamics Investigations (GEDI) mission will provide systematically data on the vertical structure of the vegetation, but its use presents some challenges compared to the common discrete-return airborne LiDAR. GEDI will be a waveform instrument, hence the summary metrics will be different to those obtained with airborne LiDAR, and the sampling configuration could limit the utility of the data, especially on heterogeneous landscapes. The potential use of GEDI data for forest characterization at the stand level would therefore depend on the predictive power of the GEDI footprint metrics, and on the density of point samples relative to forest stand size (i.e. the number of observation/footprints per stand).In this study, we assess the performance of simulated GEDI-derived metrics for stand characterization and estimation of TSD, and the point density needed to adequately identify forest stands, which translates - due to the fixed sampling configuration - into the minimum temporal interval needed to collect a sufficient number of points. The study area was located in the Clear Creek, Selway River

Facilitating the recovery of natural evergreen forests in South Africa via invader plant stands

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Coert J. Geldenhuys

2017-11-01

Full Text Available Contrary to general belief, planted and naturalized stands of introduced species facilitate the recovery of natural evergreen forests and their diversity. Forest rehabilitation actions are often performed at great cost: mature forest species are planted, while species with adaptations to recover effectively and quickly after severe disturbance are ignored; or stands are cleared of invasive alien species before native tree species are planted. By contrast, cost-effective commercial plantation forestry systems generally use fast-growing pioneer tree species introduced from other natural forest regions. Such planted tree stands often facilitate the recovery of shade-tolerant native forest species. This paper provides a brief overview of disturbance-recovery processes at landscape level, and how pioneer stands of both native and introduced tree species develop from monocultures to diverse mature forest communities. It uses one example of a study of how natural forest species from small forest patches of 3 ha in total invaded a 90-ha stand of the invasive Black wattle, Acacia mearnsii, over a distance of 3.1 ha at Swellendam near Cape Town, South Africa. The study recorded 329 forest species clusters across the wattle stand: more large clusters closer to and more smaller clusters further away from natural forest patches. The 28 recorded forest species (of potentially 40 species in the surrounding forest patches included 79% tree and 21% shrub species. Colonizing forest species had mostly larger fleshy fruit and softer small seeds, and were dispersed by mostly birds and primate species. Maturing forest trees within developing clusters in the wattle stand became a source for forest regeneration away from the clusters, showing different expansion patterns. Four sets of fenced-unfenced plots in the wattle stand showed the impact of browsing by livestock, antelope, rodents and insects on the successful establishment of regenerating forest species, and the

Forecast for the dynamics of forests in Krasnoyarsk Krai

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V. A. Sokolov

2017-08-01

Full Text Available Dynamics of the forest ecosystems connects closely with the natural and anthropogenic changes (succession processes, forest fires, windfalls, forest insects, forest diseases, forest harvesting, reforestation, the infrastructure development associated and not associated with forestry and so forth. Authors do not consider the up-to-day problem of global warming on the Earth, as opinions of scientists are controversial. Retrospective analysis of forest dynamics of the Krasnoyarsk Territory for the last 50 years has allowed to assess the impact of these changes on condition of forests. The univocal conclusion of deterioration of forest quality has been drawn. Area of coniferous forests has decreased by 9 %, including the 25 % reduction of mature and overmature forest stands. To forecast forest dynamics, modelling of natural and anthropogenic processes in the forest ecosystems has been applied, taking into account that the existing system of measures for reforestation and tending care of forest actually does not affect dynamics of the forests. The provision about increase in forest harvesting volume to 37.6 million м3 of the Development Strategy of the Krasnoyarsk Forest Industrial Complex has been used for forecasting. It has been proved that such scale of forest harvesting will inevitably lead to the over-cutting of ecological and economic accessible allowable cut that will negatively affect the forest condition in 50 years. Our forecast of forest dynamics of the Krasnoyarsk Territory for the next 50 years has showed that negative changes will continue at the same pace under the current extensive form of forest management. What is more, the maximum decrease of forest area might be in pine forests (32.9 % with the significant increase of broadleaves forests – 22.7 %. To improve the situation in the Russian forest sector, a radical change in the system of forest management is needed.

Forest stand structure, productivity, and age mediate climatic effects on aspen decline

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Bell, David M.; Bradford, John B.; Lauenroth, William K.

2014-01-01

Because forest stand structure, age, and productivity can mediate the impacts of climate on quaking aspen (Populus tremuloides) mortality, ignoring stand-scale factors limits inference on the drivers of recent sudden aspen decline. Using the proportion of aspen trees that were dead as an index of recent mortality at 841 forest inventory plots, we examined the relationship of this mortality index to forest structure and climate in the Rocky Mountains and Intermountain Western United States. We found that forest structure explained most of the patterns in mortality indices, but that variation in growing-season vapor pressure deficit and winter precipitation over the last 20 years was important. Mortality index sensitivity to precipitation was highest in forests where aspen exhibited high densities, relative basal areas, quadratic mean diameters, and productivities, whereas sensitivity to vapor pressure deficit was highest in young forest stands. These results indicate that the effects of drought on mortality may be mediated by forest stand development, competition with encroaching conifers, and physiological vulnerabilities of large trees to drought. By examining mortality index responses to both forest structure and climate, we show that forest succession cannot be ignored in studies attempting to understand the causes and consequences of sudden aspen decline.

Relationships between net primary productivity and forest stand age in U.S. forests

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Liming He; Jing M. Chen; Yude Pan; Richard Birdsey; Jens. Kattge

2012-01-01

Net primary productivity (NPP) is a key flux in the terrestrial ecosystem carbon balance, as it summarizes the autotrophic input into the system. Forest NPP varies predictably with stand age, and quantitative information on the NPP-age relationship for different regions and forest types is therefore fundamentally important for forest carbon cycle modeling. We used four...

Coevolution of floodplain and riparian forest dynamics on large, meandering rivers

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Stella, J. C.; Riddle, J. D.; Battles, J. J.

2012-12-01

On large meandering rivers, riparian forests coevolve with the floodplains that support them. Floodplain characteristics such as local disturbance regime, deposition rates and sediment texture drive plant community dynamics, which in turn feed back to the abiotic processes. We investigated floodplain and riparian forest coevolution along the along the Sacramento River (California, USA), a large, mediterranean-climate river that has been extensively regulated for 70 years, but whose 160-km middle reach (Red Bluff to Colusa) retains some channel mobility and natural forest stands. Guided by maps of floodplain change over time and current vegetation cover, we conducted an extensive forest inventory and chronosequence analysis to quantify how abiotic conditions and forest structural characteristics such as tree density, basal area and biomass vary with floodplain age. We inventoried 285 fixed-area plots distributed across 19 large point bars within vegetation patches ranging in age from 4 to 107 years. Two successional trajectories were evident: (1) shifting species dominance over time within forested areas, from willow to cottonwood to walnut, boxelder and valley oak; and (2) patches of shrub willow (primarily Salix exigua) that maintained dominance throughout time. Sediment accretion was reduced in the persistent willow plots compared to the successional forest stands, suggesting an association between higher flood energy and arrested succession. Forested stands 40-60 years old were the most extensive across the chronosequence in terms of floodplain area, and supported the highest biomass, species diversity, and functional wildlife habitat. These stands were dominated by Fremont cottonwood (Populus fremontii) and reached their maxima in terms of tree size and biomass at age 50 years. The persistent willow stands reached their structural maxima earlier (32 years) and supported lower biomass. Basal area and abundance of large trees decreased in stands >90 years old

When a tree falls: Controls on wood decay predict standing dead tree fall and new risks in changing forests

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Brad Oberle; Kiona Ogle; Amy E. Zanne; Christopher W. Woodall

2018-01-01

When standing dead trees (snags) fall, they have major impacts on forest ecosystems. Snag fall can redistribute wildlife habitat and impact public safety, while governing important carbon (C) cycle consequences of tree mortality because ground contact accelerates C emissions during deadwood decay. Managing the consequences of altered snag dynamics in changing forests...

Predicting temperate forest stand types using only structural profiles from discrete return airborne lidar

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Fedrigo, Melissa; Newnham, Glenn J.; Coops, Nicholas C.; Culvenor, Darius S.; Bolton, Douglas K.; Nitschke, Craig R.

2018-02-01

Light detection and ranging (lidar) data have been increasingly used for forest classification due to its ability to penetrate the forest canopy and provide detail about the structure of the lower strata. In this study we demonstrate forest classification approaches using airborne lidar data as inputs to random forest and linear unmixing classification algorithms. Our results demonstrated that both random forest and linear unmixing models identified a distribution of rainforest and eucalypt stands that was comparable to existing ecological vegetation class (EVC) maps based primarily on manual interpretation of high resolution aerial imagery. Rainforest stands were also identified in the region that have not previously been identified in the EVC maps. The transition between stand types was better characterised by the random forest modelling approach. In contrast, the linear unmixing model placed greater emphasis on field plots selected as endmembers which may not have captured the variability in stand structure within a single stand type. The random forest model had the highest overall accuracy (84%) and Cohen's kappa coefficient (0.62). However, the classification accuracy was only marginally better than linear unmixing. The random forest model was applied to a region in the Central Highlands of south-eastern Australia to produce maps of stand type probability, including areas of transition (the 'ecotone') between rainforest and eucalypt forest. The resulting map provided a detailed delineation of forest classes, which specifically recognised the coalescing of stand types at the landscape scale. This represents a key step towards mapping the structural and spatial complexity of these ecosystems, which is important for both their management and conservation.

A method of forest management for the planned introduction of intensive husbandry in virgin forest stands

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B. Dolezal

1978-01-01

The method proposed is derived from long experience of intensive management in forest stands of Central Europe and from our proposal for management in virgin Iranian forests of the Caspian Region. The method establishes the need for systematic planning of stand conversion to insure both sustained yield and the harvesting of sufficient timber to sustain economic...

Soil fauna as an indicator of soil quality in forest stands, pasture and secondary forest

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Felipe Vieira da Cunha Neto

2012-11-01

Full Text Available The interactions between soil invertebrates and environmental variations are relatively unknown in the assessment of soil quality. The objective of this study was to evaluate soil quality in areas with different soil management systems, based on soil fauna as indicator, in Além Paraíba, Minas Gerais, Brazil. The soil invertebrate community was sampled using pitfall traps, in the dry and rainy seasons, from areas with five vegetation types (acacia, mimosa, eucalyptus, pasture, and secondary forest. The abundance of organisms and the total and average richness, Shannon's diversity index, the Pielou uniformity index, and change index V were determined. The fauna was most abundant in the areas of secondary forest and mimosa plantations in the dry season (111.3 and 31.7 individuals per trap per day, respectively. In the rainy season, the abundance of organisms in the three vegetation types did not differ. The highest values of average and total richness were recorded in the secondary forest in the dry season and in the mimosa stand in the rainy season. Shannon's index ranged from 1.57 in areas with acacia and eucalyptus in the rainy season to 3.19 in the eucalyptus area in the dry season. The uniformity index was highest in forest stands (eucalyptus, acacia and mimosa in the dry season, but higher in the rainy season in the pasture and secondary forest than in the forest stands. The change index V indicated that the percentage of extremely inhibited groups was lowest in the area with mimosa, both in the dry and rainy season (36 and 23 %, respectively. Of all forest stands, the mimosa area had the most abundant soil fauna.

Neural network modelling of rainfall interception in four different forest stands

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İbrahim Yurtseven

2013-11-01

Full Text Available The objective of this study is to reveal whether it is possible to predict rainfall, through fall and stem flow in forest ecosystems with less effort, using several measurements of rainfall interception (hereafter ‘interception’ and an artificial neural network based linear regression model (ANN model. To this end, the Kerpe Research Forest in the province of Kocaeli, which houses stands of mixed deciduous-broadleaf forest (Castanea sativa Mill., Fagusorientalis Lipsky, Quercus spp., black pine (Pinus nigra Arnold, maritime pine (Pinus pinaster Aiton and Monterey pine (Pinus radiata D. Don, was selected study site. Four different forest stands were observed for a period of two years, during which rainfall, throughfall and stemflow measurements were conducted. These measurements were separately calculated for each individual stand, based on interception values and the use of stemflow data in strict accordance with the rainfall data, and the measured throughfall interceptionvalues were compared with values estimated by the ANN model.In this comparison, 70% of the total data was used for testing, and 30% was used for estimation and performance evaluation. No significant differences were found between values predicted with the help of the model and the measured values. In other words, interception values predicted by the ANN models were parallel with the measured values. In this study, the most success was achieved with the models of the Monterey pine stand (r2 = 0.9968; Mean Squared Error MSE = 0.16 and the mixed deciduous forest stand (r2 = 0.9964; MSE = 0.08, followed by models of the maritime pine stand (r2 = 0.9405; MSE = 1.27 and the black pine stand (r2 = 0.843, MSE = 17.36.

Perspectives for the application of computer models to forest dynamics forecasting in bieszczadzki national park (Poland

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Kozak Ihor

2014-03-01

Full Text Available This paper presents the perspectives for application of computer models in forecasting the dynamics of forest development on example of Moczarne area, in Bieszczadzki National Park, based on authors’ computer models. First, the possibilities for forecasting the dynamics of forest development in a local scale, i.e. within single rectangular or circular study plot, are presented. For this purpose, a computer prognostic model FORKOM E has been applied, using both general mathematical relationships functioning within a forest ecosystem and empirical ones, characteristic for tree stands at analysed plots. Additionally, a layer of 3D visualisation of a tree stand, which is an integral part of the mentioned model, is also presented. Presented also are the possibilities for forecasting the dynamics of forest development at landscape scale, applying the theory of cellular automata. For this purpose, a prognostic computer model CELLAUT was used in which the whole analysed tree stand is understood as a set of single cells, where stages of landscape development dominating within those cells are considered as also the influence of particular cells upon their neighbours. The paper also describes the perspectives for application of self-learning neural networks in the process of supplementation and verification of some parameters of a tree stand, calculated by the above-mentioned models.

Canopy transpiration of pure and mixed forest stands with variable abundance of European beech

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Gebauer, Tobias; Horna, Viviana; Leuschner, Christoph

2012-06-01

SummaryThe importance of tree species identity and diversity for biogeochemical cycles in forests is not well understood. In the past, forestry has widely converted mixed forests to pure stands while contemporary forest policy often prefers mixed stands again. However, the hydrological consequences of these changes remain unclear. We tested the hypotheses (i) that significant differences in water use per ground area exist among the tree species of temperate mixed forests and that these differences are more relevant for the amount of stand-level canopy transpiration (Ec) than putative complementarity effects of tree water use, and (ii) that the seasonal patterns of Ec in mixed stands are significantly influenced by the identity of the present tree species. We measured xylem sap flux during 2005 (average precipitation) and 2006 (relatively dry) synchronously in three nearby old-growth forest stands on similar soil differing in the abundance of European beech (pure beech stand, 3-species stand with 70% beech, 5-species stand with sapwood area basis, reflecting a considerable variation in hydraulic architecture and leaf conductance regulation among the co-existing species. Moreover, transpiration per crown projection area (ECA) also differed up to 5-fold among the different species in the mixed stands, probably reflecting contrasting sapwood/crown area ratios. We conclude that Ec is not principally higher in mixed forests than in pure beech stands. However, tree species-specific traits have an important influence on the height of Ec and affect its seasonal variation. Species with a relatively high ECA (notably Tilia) may exhaust soil water reserves early in summer, thereby increasing drought stress in dry years and possibly reducing ecosystem stability in mixed forests.

Surface forcing of non-stand-replacing fires in Siberian larch forests

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Chen, Dong; Loboda, Tatiana V.

2018-04-01

Wildfires are the dominant disturbance agent in the Siberian larch forests. Extensive low- to mediate-intensity non-stand-replacing fires are a notable property of fire regime in these forests. Recent large scale studies of these fires have focused mostly on their impacts on carbon budget; however, their potential impacts on energy budget through post-fire albedo changes have not been considered. This study quantifies the post-fire surface forcing for Siberian larch forests that experienced non-stand-replacing fires between 2001 and 2012 using the full record of MODIS MCD43A3 albedo product and a burned area product developed specifically for the Russian forests. Despite a large variability, the mean effect of non-stand-replacing fires imposed through albedo is a negative forcing which lasts for at least 14 years. However, the magnitude of the forcing is much smaller than that imposed by stand-replacing fires, highlighting the importance of differentiating between the two fire types in the studies involving the fire impacts in the region. The results of this study also show that MODIS-based summer differenced normalized burn ratio (dNBR) provides a reliable metric for differentiating non-stand-replacing from stand-replacing fires with an overall accuracy of 88%, which is of considerable importance for future work on modeling post-fire energy budget and carbon budget in the region.

Neural network modelling of rainfall interception in four different forest stands

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Ibrahim Yurtseven

2013-12-01

Full Text Available The objective of this study is to reveal whether it is possible to predict rainfall, throughfall and stemflow in forest ecosystems with less effort, using several measurements of rainfall interception (hereafter ‘interception’ and an artificial neural network based linear regression model (ANN model. To this end, the Kerpe Research Forest in the province of Kocaeli, which houses stands of mixed deciduous-broadleaf forest (Castanea sativa Mill., Fagus orientalis Lipsky, Quercus spp., black pine (Pinus nigra Arnold, maritime pine (Pinus pinaster Aiton and Monterey pine (Pinus radiata D. Don, was selected study site. Four different forest stands were observed for a period of two years, during which rainfall, throughfall and stemflow measurements were conducted. These measurements were separately calculated for each individual stand, based on interception values and the use of stemflow data in strict accordance with the rainfall data, and the measured throughfall interception values were compared with values estimated by the ANN model. In this comparison, 70% of the total data was used for testing, and 30% was used for estimation and performance evaluation. No significant differences were found between values predicted with the help of the model and the measured values. In other words, interception values predicted by the ANN models were parallel with the measured values. In this study, the most success was achieved with the models of the Monterey pine stand (r2 = 0.9968; Mean Squared Error MSE = 0.16 and the mixed deciduous forest stand (r2 = 0.9964; MSE = 0.08, followed by models of the maritime pine stand (r2 = 0.9405; MSE = 1.27 and the black pine stand (r2 = 0.843, MSE = 17.36.

[Carbon storage of forest stands in Shandong Province estimated by forestry inventory data].

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Li, Shi-Mei; Yang, Chuan-Qiang; Wang, Hong-Nian; Ge, Li-Qiang

2014-08-01

Based on the 7th forestry inventory data of Shandong Province, this paper estimated the carbon storage and carbon density of forest stands, and analyzed their distribution characteristics according to dominant tree species, age groups and forest category using the volume-derived biomass method and average-biomass method. In 2007, the total carbon storage of the forest stands was 25. 27 Tg, of which the coniferous forests, mixed conifer broad-leaved forests, and broad-leaved forests accounted for 8.6%, 2.0% and 89.4%, respectively. The carbon storage of forest age groups followed the sequence of young forests > middle-aged forests > mature forests > near-mature forests > over-mature forests. The carbon storage of young forests and middle-aged forests accounted for 69.3% of the total carbon storage. Timber forest, non-timber product forest and protection forests accounted for 37.1%, 36.3% and 24.8% of the total carbon storage, respectively. The average carbon density of forest stands in Shandong Province was 10.59 t x hm(-2), which was lower than the national average level. This phenomenon was attributed to the imperfect structure of forest types and age groups, i. e., the notably higher percentage of timber forests and non-timber product forest and the excessively higher percentage of young forests and middle-aged forest than mature forests.

Stand, species, and individual traits impact transpiration in historically disturbed forests.

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Blakely, B.; Rocha, A. V.; McLachlan, J. S.

2017-12-01

Historic logging disturbances have changed the structure and species composition of most Northern temperate forests. These changes impact the process of transpiration - which in turn impacts canopy surface temperature - but the links among structure, composition, and transpiration remain unclear. For this reason, ecosystem models typically use simplified structure and composition to simulate the impact of disturbances on forest transpiration. However, such simplifications ignore real variability among stands, species, and individual trees that may strongly influence transpiration across spatial and temporal scales. To capture this variability, we monitored transpiration in 48 individual trees of multiple species in both undisturbed (400+ yr) and historically logged (80 - 120 yr) forests. Using modern and historic forest surveys, we upscaled our observations to stand and regional scales to identify the key changes impacting transpiration. We extended these inferences by establishing a relationship between transpiration and measured surface temperature, linking disturbance-induced changes in structure and composition to local and regional climate. Despite greater potential evapotranspiration and basal area, undisturbed forest transpired less than disturbed (logged) forest. Transpiration was a strong predictor of surface temperature, and the canopy surface was warmer in undisturbed forest. Transpiration differences among disturbed and undisturbed forests resulted from (1) lesser transpiration and dampened seasonality in evergreen species (2) greater transpiration in younger individuals within a species, and (3) strong transpiration by large individuals. When transpiration was scaled to the stand or regional level in a simplified manner (e.g. a single transpiration rate for all deciduous individuals), the resulting estimates differed markedly from the original. Stand- species- and individual-level traits are therefore essential for understanding how transpiration and

Forest volume-to-biomass models and estimates of mass for live and standing dead trees of U.S. forests.

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James E. Smith; Linda S. Heath; Jennifer C. Jenkins

2003-01-01

Includes methods and equations for nationally consistent estimates of tree-mass density at the stand level (Mg/ha) as predicted by growing-stock volumes reported by the USDA Forest Service for forests of the conterminous United States. Developed for use in FORCARB, a carbon budget model for U.S. forests, the equations also are useful for converting plot-, stand- and...

Carbon content of forest floor and mineral soil in Mediterranean Pinus spp. and Oak stands in acid soils in Northern Spain

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Herrero, C.; Turrión, M.B.; Pando, V.; Bravo, F.

2016-07-01

Aim of the study: The aim of the study was to determine the baseline carbon stock in forest floor and mineral soils in pine and oak stands in acid soils in Northern Spain. Area of study: The study area is situated in northern Spain (42° N, 4° W) on “Paramos y Valles” region of Palencia. aterial and methods: An extensive monitoring composed of 48 plots (31 in pine and 17 in oak stands) was carried out. Litter layers and mineral soil samples, at depths of 0-30 cm and 30-60 cm, were taken in each plot. An intensive monitoring was also performed by sampling 12 of these 48 plots selected taken in account species forest composition and their stand development stage. Microbial biomass C (CMB), C mineralization (CRB), and soil organic C balance at stand level were determined in surface soil samples of intensive monitoring. Main results: No differences in soil C content were detected in the two forest ecosystems up to 60 cm depth (53.0±25.8 Mg C ha-1 in Pinus spp. plantations and 60.3±43.8 Mg C ha-1 in oak stands). However, differences in total C (CT), CMB and CRB were found in the upper 10 cm of the soils depending on the stand development stage in each species forest composition (Pinus nigra, Pinus pinaster, Pinus sylvestris and Quercus pyrenaica). Plots with high development stage exhibited significant lower metabolic quotient (qCO2), so, meant more efficient utilization of C by the microbial community. The C content in the forest floor was higher in pine stands (13.7±0.9 Mg C ha-1) than in oak stands (5.4±0.7 Mg C ha-1). A greater turnover time was found in pine ecosystems vs. oak stands. In contrast, forest floor H layer was nonexistent in oak stands. Research highlights: Results about litterfall, forest floor and mineral soil dynamics in this paper can be used strategically to reach environmental goals in new afforestation programs and sustainable forest management approaches. (Author)

A 3D stand generator for central Appalachian hardwood forests

Science.gov (United States)

Jingxin Wang; Yaoxiang Li; Gary W. Miller

2002-01-01

A 3-dimensional (3D) stand generator was developed for central Appalachian hardwood forests. It was designed for a harvesting simulator to examine the interactions of stand, harvest, and machine. The Component Object Model (COM) was used to design and implement the program. Input to the generator includes species composition, stand density, and spatial pattern. Output...

Quantitative Analysis of Complex Tropical Forest Stands: A Review ...

African Journals Online (AJOL)

The importance of data analysis in quantitative assessment of natural resources remains significant in the sustainable management of complex tropical forest resources. Analyses of data from complex tropical forest stands have not been easy or clear due to improper data management. It is pivotal to practical researches ...

Development, succession, and stand dynamics of upland oak forests in the Wisconsin Driftless Area: Implications for oak regeneration and management

Science.gov (United States)

Megan L. Buchanan; Kurt F. Kipfmueller; Anthony W. D' Amato

2017-01-01

Throughout the deciduous forests of the eastern United States, oak (Quercus) regeneration has declined in stands historically dominated by oak species. In the Wisconsin Driftless Area, the level of decline in oak regeneration is variable and influenced by stand structural development, historical disturbance regime, abiotic site characteristics, and...

Stand-replacing wildfires increase nitrification for decades in southwestern ponderosa pine forests.

Science.gov (United States)

Kurth, Valerie J; Hart, Stephen C; Ross, Christopher S; Kaye, Jason P; Fulé, Peter Z

2014-05-01

Stand-replacing wildfires are a novel disturbance within ponderosa pine (Pinus ponderosa) forests of the southwestern United States, and they can convert forests to grasslands or shrublands for decades. While most research shows that soil inorganic N pools and fluxes return to pre-fire levels within a few years, we wondered if vegetation conversion (ponderosa pine to bunchgrass) following stand-replacing fires might be accompanied by a long-term shift in N cycling processes. Using a 34-year stand-replacing wildfire chronosequence with paired, adjacent unburned patches, we examined the long-term dynamics of net and gross nitrogen (N) transformations. We hypothesized that N availability in burned patches would become more similar to those in unburned patches over time after fire as these areas become re-vegetated. Burned patches had higher net and gross nitrification rates than unburned patches (P < 0.01 for both), and nitrification accounted for a greater proportion of N mineralization in burned patches for both net (P < 0.01) and gross (P < 0.04) N transformation measurements. However, trends with time-after-fire were not observed for any other variables. Our findings contrast with previous work, which suggested that high nitrification rates are a short-term response to disturbance. Furthermore, high nitrification rates at our site were not simply correlated with the presence of herbaceous vegetation. Instead, we suggest that stand-replacing wildfire triggers a shift in N cycling that is maintained for at least three decades by various factors, including a shift from a woody to an herbaceous ecosystem and the presence of fire-deposited charcoal.

Logging impacts on forest structure and seedling dynamics in a Prioria copaifera (Fabaceae) dominated tropical rain forest (Talamanca, Costa Rica).

Science.gov (United States)

Valverde-Barrantes, Oscar J; Rocha, Oscar J

2014-03-01

The factors that determine the existence of tropical forests dominated by a single species (monodominated forests) have been the subject of debate for a long time. It has been hypothesized that the low frequency of disturbances in monodominated forests and the tolerance to shade of the monodominant species are two important factors explaining the prolonged dominance of a single species. We determined the role of these two factors by examining the effects of logging activities on the floristic composition and seedling dynamics in a Prioria copaifera dominated forest in Southeastern Costa Rica. We determined the floristic composition for trees > or = 2.5cm DBH and the associated recruitment, survival and mortality of tree canopy seedlings in two sites logged two (L-02) and 12 years (L-12) prior to sampling and an unlogged forest (ULF). Our results showed that L-02 stands had lower species richness (25 species) than the L-12 and ULF stands (49 and 46 species, respectively). As expected, we found significant logging effects on the canopy structure of the altered forests, particularly when comparing the L-02 and the ULF stands. Seedling density was higher in ULF (0.96 seedlings/ m2) than in the L-02 and L-12 stands (0.322 and 0.466 seedlings/m2, respectively). However, seedling mortality was higher in the ULF stands (54%) than in the L-02 (26%) and L-12 (15%) stands. P. macroloba in L-02 was the only species with abundant regeneration under P. copaifera in L-02 stand, where it accounted for 35% of the seedlings. Despite the reduction in seedling abundance observed after logging, P. copaifera seems to maintain large seedling populations in these forests, suggesting that this species maintains its dominance after logging disturbances. Our findings challenge the hypothesis that the regeneration of monodominant species is not likely to occur under heavily disturbed canopy conditions.

Logging impacts on forest structure and seedling dynamics in a Prioria copaifera (Fabaceae dominated tropical rain forest (Talamanca, Costa Rica

Directory of Open Access Journals (Sweden)

Oscar J. Valverde-Barrantes

2014-03-01

Full Text Available The factors that determine the existence of tropical forests dominated by a single species (monodominated forests have been the subject of debate for a long time. It has been hypothesized that the low frequency of disturbances in monodominated forests and the tolerance to shade of the monodominant species are two important factors explaining the prolonged dominance of a single species. We determined the role of these two factors by examining the effects of logging activities on the floristic composition and seedling dynamics in a Prioria copaifera dominated forest in Southeastern Costa Rica. We determined the floristic composition for trees ≥2.5cm DBH and the associated recruitment, survival and mortality of tree canopy seedlings in two sites logged two (L-02 and 12 years (L-12 prior to sampling and an unlogged forest (ULF. Our results showed that L-02 stands had lower species richness (25 species than the L-12 and ULF stands (49 and 46 species, respectively. As expected, we found significant logging effects on the canopy structure of the altered forests, particularly when comparing the L-02 and the ULF stands. Seedling density was higher in ULF (0.96 seedlings/m² than in the L-02and L-12 stands (0.322 and 0.466 seedlings/m², respectively. However, seedling mortality was higher in the ULF stands (54% than in the L-02 (26% and L-12 (15% stands. P. macroloba in L-02 was the only species with abundant regeneration under P. copaifera in L-02 stand, where it accounted for 35% of the seedlings. Despite the reduction in seedling abundance observed after logging, P. copaifera seems to maintain large seedling populations in these forests, suggesting that this species maintains its dominance after logging disturbances. Our findings challenge the hypothesis that the regeneration of monodominant species is not likely to occur under heavily disturbed canopy conditions. Rev. Biol. Trop. 62 (1: 347-357. Epub 2014 March 01.

Forest Stand Segmentation Using Airborne LIDAR Data and Very High Resolution Multispectral Imagery

Science.gov (United States)

Dechesne, Clément; Mallet, Clément; Le Bris, Arnaud; Gouet, Valérie; Hervieu, Alexandre

2016-06-01

Forest stands are the basic units for forest inventory and mapping. Stands are large forested areas (e.g., ≥ 2 ha) of homogeneous tree species composition. The accurate delineation of forest stands is usually performed by visual analysis of human operators on very high resolution (VHR) optical images. This work is highly time consuming and should be automated for scalability purposes. In this paper, a method based on the fusion of airborne laser scanning data (or lidar) and very high resolution multispectral imagery for automatic forest stand delineation and forest land-cover database update is proposed. The multispectral images give access to the tree species whereas 3D lidar point clouds provide geometric information on the trees. Therefore, multi-modal features are computed, both at pixel and object levels. The objects are individual trees extracted from lidar data. A supervised classification is performed at the object level on the computed features in order to coarsely discriminate the existing tree species in the area of interest. The analysis at tree level is particularly relevant since it significantly improves the tree species classification. A probability map is generated through the tree species classification and inserted with the pixel-based features map in an energetical framework. The proposed energy is then minimized using a standard graph-cut method (namely QPBO with α-expansion) in order to produce a segmentation map with a controlled level of details. Comparison with an existing forest land cover database shows that our method provides satisfactory results both in terms of stand labelling and delineation (matching ranges between 94% and 99%).

Climate change impact on landscape fire and forest biomass dynamics

International Nuclear Information System (INIS)

Li, C.

2004-01-01

The aim of this study was to improve current understandings of fire regimes. The estimation of biomass dynamics at the stand scale is essential for understanding landscape scale biomass dynamics, particularly in order to understand the potential effects of fire regimes. This study presented a synthesis of research results obtained from stand scale studies together with fire behaviour and weather variables. Landscape structure, topography and climate conditions were also considered. Integration of the data was conducted with the SEM-LAND model, a spatially explicit model for landscape dynamics. Equations for the model were presented, including fire initiation and spread, as well as a lightning fire process and simulated fire suppression. Results indicated that fire suppression could alter the distribution of fire sizes. The effect of tree and stand mortality on forest biomass estimates was also discussed along with the impact of climate change on fire regimes. Results indicate that fire activities are likely to increase. Results also demonstrate that fire frequency and size distribution are correlated without human intervention. Theoretical negative exponential forest age distribution is not always supported by empirical observations. Point-based fire frequency and fire cycle definitions are special cases from a computational perspective. Detection of quantitative interrelationships may simplify preconditions for estimating fire regimes, and serve as a means to address incomplete empirical observations. 12 refs., 3 figs

Surface albedo in relation to disturbance and early stand dynamics in the boreal forest: Implications for climate models

Science.gov (United States)

Halim, M. A.; Thomas, S. C.

2017-12-01

Surface albedo is the most important biophysical radiative forcing in the boreal forest. General Circulation Model studies have suggested that harvesting of boreal forest has a net cooling effect, in contrast to other terrestrial biomes, by increasing surface albedo. However, albedo estimation in these models has been achieved by simplifying processes governing albedo at a coarse scale (both spatial and temporal). Biophysical processes that determine albedo likely operate on small spatial and temporal scales, requiring more direct estimates of effects of landcover change on net radiation. We established a chronosequence study in post-fire and post-clearcut sites (2013, 2006, 1998), logging data from July 2013 to July 2017 in boreal forest sites in northwestern Ontario, Canada. Each age-class X disturbance had 3 three replicates, matched to 18 permanent circular plots (10-m radius) each with an instrumented tower measuring surface albedo, air and soil temperature, and soil moisture. We also measured leaf area index, species composition and soil organic matter content at each site. BRDF-corrected surface albedo was calculated from daily 30m x 30m reflectance data fused from the MODIS MOD09GA product and Landsat 7 reflectance data. Calculated albedo was verified using ground-based measurements. Results show that fire sites generally had lower (15-25%) albedo than clearcut sites in all seasons. Because of rapid forest regrowth, large perturbations of clearcut harvests on forest albedo started to fade out within a year. Albedo differences between fire and clearcut sites also declined sharply with stand age. Younger stands generally had higher albedo than older stands mainly due to the presence of broadleaf species (for example, Populus tremuloides). In spring, snow melted 10-12 days earlier in recent (2013) clearcut sites compared to closed-canopy sites, causing a sharp reduction in surface albedo in comparison to old clearcut/fire sites (2006 and 1998). Snow melted

Patterns of covariance between forest stand and canopy structure in the Pacific Northwest.

Science.gov (United States)

Michael A. Lefsky; Andrew T. Hudak; Warren B. Cohen; S.A. Acker

2005-01-01

In the past decade, LIDAR (light detection and ranging) has emerged as a powerful tool for remotely sensing forest canopy and stand structure, including the estimation of aboveground biomass and carbon storage. Numerous papers have documented the use of LIDAR measurements to predict important aspects of forest stand structure, including aboveground biomass. Other...

Initial observations on tree mortality following a severe drought in 2012 in two Indiana state forests and implications for long-term compositional dynamics

Science.gov (United States)

Andrew R. Meier; Mike R. Saunders

2014-01-01

Compositional and structural changes in response to silvicultural treatments in forest stands are well documented (e.g., Saunders and Wagner 2008), but the stochastic nature of natural disturbance events often precludes direct observation of their impacts on stand dynamics. Though the current dominance of oak-hickory forest types in the Central Hardwoods Forest region...

A Stand-Class Growth and Yield Model for Mexico’s Northern Temperate, Mixed and Multiaged Forests

Directory of Open Access Journals (Sweden)

José Návar

2014-12-01

Full Text Available The aim of this research was to develop a stand-class growth and yield model based on the diameter growth dynamics of Pinus spp. and Quercus spp. of Mexico’s mixed temperate forests. Using a total of 2663 temporary, circular-sampling plots of 1000 m2 each, nine Weibull distribution techniques of parameter estimation were fitted to the diameter structures of pines and oaks. Statistical equations using stand attributes and the first three moments of the diameter distribution predicted and recovered the Weibull parameters. Using nearly 1200 and 100 harvested trees for pines and oaks, respectively, I developed the total height versus diameter at breast height relationship by fitting three non-linear functions. The Newnham model predicted stem taper and numerical integration was done to estimate merchantable timber volume for all trees in the stand for each diameter class. The independence of the diameter structures of pines and oaks was tested by regressing the Weibull parameters and projecting diameter structures. The model predicts diameter distributions transition from exponential (J inverse, logarithmic to well-balanced distributions with increasing mean stand diameter at breast height. Pine diameter distributions transition faster and the model predicts independent growth rates between pines and oaks. The stand-class growth and yield model must be completed with the diameter-age relationship for oaks in order to carry a full optimization procedure to find stand density and genera composition to maximize forest growth.

Object-oriented classification of forest structure from light detection and ranging data for stand mapping

Science.gov (United States)

Alicia A. Sullivan; Robert J. McGaughey; Hans-Erik Andersen; Peter. Schiess

2009-01-01

Stand delineation is an important step in the process of establishing a forest inventory and provides the spatial framework for many forest management decisions. Many methods for extracting forest structure characteristics for stand delineation and other purposes have been researched in the past, primarily focusing on high-resolution imagery and satellite data. High-...

Public Preferences Across Europe for Different Forest Stand Types as Sites for Recreation

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David M. Edwards

2012-03-01

Full Text Available A Delphi survey involving experts in forest preference research was carried out to derive scores for the recreational value of 240 forest stand types across Europe. The survey was organized around four regional panels: Great Britain, Nordic Region, Central Europe, and Iberia. In each region, 60 forest stand types were defined according to five forest management alternatives (FMAs on a continuum of management intensity, four phases of development (establishment, young, medium, and adult, and three tree species types (conifer, broadleaved, and mixed stands of conifer and broadleaved. The resulting scores were examined using conjoint analysis to determine the relative importance of the three structural attributes (FMA, phase of development, and tree species type, and each level or component of the attributes. The findings quantify the extent to which forest visitors prefer a degree of management to unmanaged forest nature reserves across the four regions. Phase of development was shown to make the highest contribution to the recreational value of forests while the contribution of tree species type was shown to be relatively unimportant. While the results are indicative, they provide evidence to support long-term retention and low-impact silviculture in forests where recreation is a primary objective of management.

Long-term monitoring of diversity and structure of two stands of an Atlantic Tropical Forest.

Science.gov (United States)

Diniz, Écio Souza; Carvalho, Warley Augusto Caldas; Santos, Rubens Manoel; Gastauer, Markus; Garcia, Paulo Oswaldo; Fontes, Marco Aurélio Leite; Coelho, Polyanne Aparecida; Moreira, Aline Martins; Menino, Gisele Cristina Oliveira; Oliveira-Filho, Ary Teixeira

2017-01-01

This study aimed to report the long-term monitoring of diversity and structure of the tree community in a protected semideciduous Atlantic Forest in the South of Minas Gerais State, Southeast Brazil. The study was conducted in two stands (B and C), each with 26 and 38 10 m x 30 m plots. Censuses of stand B were conducted in 2000, 2005 and 2011, and stand C in 2001, 2006 and 2011. In both stands, the most abundant and important species for biomass accumulation over the inventories were trees larger than 20 cm of diameter, which characterize advanced successional stage within the forest. The two surveyed stands within the studied forest presented differences in structure, diversity and species richness over the time.

Predicting forested catchment evapotranspiration and streamflow from stand sapwood area and Aridity Index

Science.gov (United States)

Lane, Patrick

2016-04-01

Estimating the water balance of ungauged catchments has been the subject of decades of research. An extension of the fundamental problem of estimating the hydrology is then understanding how do changes in catchment attributes affect the water balance component? This is a particular issue in forest hydrology where vegetation exerts such a strong influence on evapotranspiration (ET), and consequent streamflow (Q). Given the primacy of trees in the water balance, and the potential for change to species and density through logging, fire, pests and diseases and drought, methods that directly relate ET/Q to vegetation structure, species, and stand density are very powerful. Plot studies on tree water use routinely use sapwood area (SA) to calculate transpiration and upscale to the stand/catchment scale. Recent work in south eastern Australian forests have found stand-wide SA to be linearly correlated (R2 = 0.89) with long term mean annual loss (P-Q), and hence, long term mean annual catchment streamflow. Robust relationships can be built between basal area (BA), tree density and stand SA. BA and density are common forest inventory measurements. Until now, no research has related the fundamental stand attribute of SA to streamflow. The data sets include catchments that have been thinned and with varying age classes. Thus far these analyses have been for energy limited systems in wetter forest types. SA has proven to be a more robust biometric than leaf area index which varies seasonally. That long term ET/Q is correlated with vegetation conforms to the Budyko framework. Use of a downscaled (20 m) Aridity Index (AI) has shown distinct correlations with stand SA, and therefore T. Structural patterns at a the hillslope scale not only correlate with SA and T, but also with interception (I) and forest floor evaporation (Es). These correlations between AI and I and Es have given R2 > 0.8. The result of these studies suggest an ability to estimate mean annual ET fluxes at sub

Potential change in forest types and stand heights in central Siberia in a warming climate

International Nuclear Information System (INIS)

Tchebakova, N M; Parfenova, E I; Korets, M A; Conard, S G

2016-01-01

Previous regional studies in Siberia have demonstrated climate warming and associated changes in distribution of vegetation and forest types, starting at the end of the 20th century. In this study we used two regional bioclimatic envelope models to simulate potential changes in forest types distribution and developed new regression models to simulate changes in stand height in tablelands and southern mountains of central Siberia under warming 21st century climate. Stand height models were based on forest inventory data (2850 plots). The forest type and stand height maps were superimposed to identify how heights would change in different forest types in future climates. Climate projections from the general circulation model Hadley HadCM3 for emission scenarios B1 and A2 for 2080s were paired with the regional bioclimatic models. Under the harsh A2 scenario, simulated changes included: a 80%–90% decrease in forest-tundra and tundra, a 30% decrease in forest area, a ∼400% increase in forest-steppe, and a 2200% increase in steppe, forest-steppe and steppe would cover 55% of central Siberia. Under sufficiently moist conditions, the southern and middle taiga were simulated to benefit from 21st century climate warming. Habitats suitable for highly-productive forests (≥30–40 m stand height) were simulated to increase at the expense of less productive forests (10–20 m). In response to the more extreme A2 climate the area of these highly-productive forests would increase 10%–25%. Stand height increases of 10 m were simulated over 35%–50% of the current forest area in central Siberia. In the extremely warm A2 climate scenario, the tall trees (25–30 m) would occur over 8%–12% of area in all forest types except forest-tundra by the end of the century. In forest-steppe, trees of 30–40 m may cover some 15% of the area under sufficient moisture. (letter)

Application of Lidar remote sensing to the estimation of forest canopy and stand structure

Science.gov (United States)

Lefsky, Michael Andrew

A new remote sensing instrument, SLICER (Scanning Lidar Imager of Canopies by Echo Recovery), has been applied to the problem of remote sensing the canopy and stand structure of two groups of deciduous forests, Tulip Poplar-Oak stands in the vicinity of Annapolis, MD. and bottomland hardwood stands near Williamston, NC. The ability of the SLICER instrument to remotely sense the vertical distribution of canopy structure (Canopy Height Profile), bulk canopy transmittance, and several indices of canopy height has been successfully validated using twelve stands with coincident field and SLICER estimates of canopy structure. Principal components analysis has been applied to canopy height profiles from both field sites, and three significant factors were identified, each closely related to the amount of foliage in a recognizable layer of the forest, either understory, midstory, or overstory. The distribution of canopy structure to these layers is significantly correlated with the size and number of stems supporting them. The same layered structure was shown to apply to both field and SLICER remotely sensed canopy height profiles, and to apply to SLICER remotely sensed canopy profiles from both the bottomland hardwood stands in the coastal plain of North Carolina, and to mesic Tulip-Poplars stands in the upland coastal plain of Maryland. Linear regressions have demonstrated that canopy and stand structure are correlated to both a statistically significant and useful degree. Stand age and stem density is more highly correlated to stand height, while stand basal area and aboveground biomass are more closely related to a new measure of canopy structure, the quadratic mean canopy height. A geometric model of canopy structure has been shown to explain the differing relationships between canopy structure and stand basal area for stands of Eastern Deciduous Forest and Douglas Fir Forest.

Implications of floristic and environmental variation for carbon cycle dynamics in boreal forest ecosystems of central Canada

Energy Technology Data Exchange (ETDEWEB)

Yu, Zicheng; Apps, M.J.; Bhatti, J.S. [Canadan Forest Service, Edmonton (Canada). Northern Forestry Centre

2002-06-01

Species composition, detritus, and soil data from 97 boreal forest stands along a transect in central Canada were analysed using Correspondence Analysis to determine the dominant environmental/site variables that differentiate these forest stands. Picea mariana stands were densely clustered together on the understorey DCA plot, suggesting a consistent understorey species composition (feather mosses and Ericaceae), whereas Populus tremuloides stands had the most diverse understorey species composition (ca. 30 species, mostly shrubs and herbs). Pinus banksiana stands had several characteristic species of reindeer lichens (Cladina spp.), but saplings and Pinus seedlings were rare. Although climatic variables showed large variation along the transect, the CCA results indicated that site conditions are more important in determining species composition and differentiating the stand types. Forest floor characteristics (litter and humus layer, woody debris, and drainage) appear to be among the most important site variables. Stands of Picea had significantly higher average carbon (C) densities in the combined litter and humus layer (43,530 kg-C/ha) than either Populus (25,500 kg-C/ha) or Pinus (19,400 kg-C/ha). The thick surface organic layer in lowland Picea stands plays an important role in regulating soil temperature and moisture, and organic-matter decomposition, which in turn affect the ecosystem C-dynamics. During forest succession after a stand-replacing disturbance (e.g. fires), tree biomass and surface organic layer thickness increase in all stand types as forests recover; however, woody biomass detritus first decreases and then increases after ca. 80 yr. Soil C densities show slight decrease with ages in Populus stands, but increase in other stand types. These results indicate the complex C-transfer processes among different components (tree biomass, detritus, forest floor, and soil) of boreal ecosystems at various stages of succession.

Piecing together the fragments: Elucidating edge effects on forest carbon dynamics

Science.gov (United States)

Hutyra, L.; Smith, I. A.; Reinmann, A.; Marrs, J.; Thompson, J.

2017-12-01

Forest fragmentation is pervasive throughout the world's forests, impacting growing conditions and carbon dynamics through edge effects that produce gradients in microclimate, biogeochemistry, and stand structure. Despite the majority of the world's forests being biome, but current forest carbon accounting methods and ecosystem models largely do not include edge effects, highlighting an important gap in our understanding of the terrestrial carbon cycle. Characterizing the role of forest fragmentation in regional and global biogeochemical cycles necessitates advancing our understanding of how shifts in microenvironment at the forest edge interact with local prevailing drivers of global change and limitations to microbial activity and forest growth. This study synthesizes the literature related to edge effects and the carbon cycle, considering how fragmentation affects the growing conditions of the world's remaining forests based on risks and opportunities for forests near the edge.

Simulating historical disturbance regimes and stand structures in old-forest ponderosa pine/Douglas-fir forests

Science.gov (United States)

Mike Hillis; Vick Applegate; Steve Slaughter; Michael G. Harrington; Helen Smith

2001-01-01

Forest Service land managers, with the collaborative assistance from research, applied a disturbance based restoration strategy to rehabilitate a greatly-altered, high risk Northern Rocky Mountain old-forest ponderosa pine-Douglas-fir stand. Age-class structure and fire history for the site have been documented in two research papers (Arno and others 1995, 1997)....

The role of forest stand structure as biodiversity indicator

DEFF Research Database (Denmark)

Gao, Tian; Hedblom, Marcus; Emilsson, Tobias

2014-01-01

be achieved if indicators are derived from existing data. In this study, a model for classifying forest stand structures was developed and tested as an indicator of overall plant species diversity at stand level. The model combines four stand structure parameters: canopy coverage, age of canopy trees, tree...... species composition and canopy stratification. Using data from the National Inventory of Landscapes in Sweden and General Linear Mixed Model, plant species diversity (Shannon diversity index, SHDI) and composition (Sørensen-Dice index, SDI) were tested between 26 different stand structure types and nine...... soil classes. The results showed that mature stands with a stratified canopy had the highest plant species diversity across the soil classes, particularly if they comprised mixed coniferous and broadleaved species with a semi-open canopy. In contrast, young (...

Stand structure and dead wood characterization in cork forest of Calabria region (southern Italy

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Barreca L

2010-07-01

Full Text Available The cork forests are one the most interesting forest ecosystems in the Mediterranean area. Their distribution and ecological characteristics have undergone a significant transformation after the significant changes following the development and establishment of agricultural crops. Currently, only a few stands, which survive in hard to reach places, prove the wide spread distribution of this species was also in the recent past. This study describes the stand structure of some cork forests in Calabria region (southern Italy. In order, to characterize the vertical structure Latham index has been applied, while for the description of the horizontal distribution NBSI group indices has been used. Detailed surveys on dead wood were also conducted determining the occurring volume and its decay stage according to the decay classes system proposed by Hunter. The aim of this study is to provide guidelines for sustainable management of cork forests, improving and promoting the structural complexity and functional efficiency of these forest stands.

Vegetation diversity of the Scots pine stands in different forest sites in the Turawa Forest District

OpenAIRE

Stefańska-Krzaczek, Ewa; Pech, Paweł

2014-01-01

The utility of phytocenotic indices in the diagnosis and classification of forest sites might be limited because of vegetation degeneration in managed forests. However, even in secondary communities it may be possible to determine indicator species, although these may differ from typical and well known plant indicators. The aim of this work was to assess the vegetation diversity of Scots pine stands in representative forest site types along a moisture and fertility gradient. In total ...

Spatial and thematic assessment of object-based forest stand delineation using an OFA-matrix

Science.gov (United States)

Hernando, A.; Tiede, D.; Albrecht, F.; Lang, S.

2012-10-01

The delineation and classification of forest stands is a crucial aspect of forest management. Object-based image analysis (OBIA) can be used to produce detailed maps of forest stands from either orthophotos or very high resolution satellite imagery. However, measures are then required for evaluating and quantifying both the spatial and thematic accuracy of the OBIA output. In this paper we present an approach for delineating forest stands and a new Object Fate Analysis (OFA) matrix for accuracy assessment. A two-level object-based orthophoto analysis was first carried out to delineate stands on the Dehesa Boyal public land in central Spain (Avila Province). Two structural features were first created for use in class modelling, enabling good differentiation between stands: a relational tree cover cluster feature, and an arithmetic ratio shadow/tree feature. We then extended the OFA comparison approach with an OFA-matrix to enable concurrent validation of thematic and spatial accuracies. Its diagonal shows the proportion of spatial and thematic coincidence between a reference data and the corresponding classification. New parameters for Spatial Thematic Loyalty (STL), Spatial Thematic Loyalty Overall (STLOVERALL) and Maximal Interfering Object (MIO) are introduced to summarise the OFA-matrix accuracy assessment. A stands map generated by OBIA (classification data) was compared with a map of the same area produced from photo interpretation and field data (reference data). In our example the OFA-matrix results indicate good spatial and thematic accuracies (>65%) for all stand classes except for the shrub stands (31.8%), and a good STLOVERALL (69.8%). The OFA-matrix has therefore been shown to be a valid tool for OBIA accuracy assessment.

A stand-replacing fire history in upper montane forests of the southern Rocky Mountains

Science.gov (United States)

Margolis, E.Q.; Swetnam, T.W.; Allen, Craig D.

2007-01-01

Dendroecological techniques were applied to reconstruct stand-replacing fire history in upper montane forests in northern New Mexico and southern Colorado. Fourteen stand-replacing fires were dated to 8 unique fire years (1842–1901) using four lines of evidence at each of 12 sites within the upper Rio Grande Basin. The four lines of evidence were (i) quaking aspen (Populus tremuloides Michx.) inner-ring dates, (ii) fire-killed conifer bark-ring dates, (iii) tree-ring width changes or other morphological indicators of injury, and (iv) fire scars. The annual precision of dating allowed the identification of synchronous stand-replacing fire years among the sites, and co-occurrence with regional surface fire events previously reconstructed from a network of fire scar collections in lower elevation pine forests across the southwestern United States. Nearly all of the synchronous stand-replacing and surface fire years coincided with severe droughts, because climate variability created regional conditions where stand-replacing fires and surface fires burned across ecosystems. Reconstructed stand-replacing fires that predate substantial Anglo-American settlement in this region provide direct evidence that stand-replacing fires were a feature of high-elevation forests before extensive and intensive land-use practices (e.g., logging, railroad, and mining) began in the late 19th century.

Carbon stocks and dynamics at different successional stages in an Afromontane tropical forest

Science.gov (United States)

Nyirambangutse, Brigitte; Zibera, Etienne; Uwizeye, Félicien K.; Nsabimana, Donat; Bizuru, Elias; Pleijel, Håkan; Uddling, Johan; Wallin, Göran

2017-03-01

As a result of different types of disturbance, forests are a mixture of stands at different stages of ecological succession. Successional stage is likely to influence forest productivity and carbon storage, linking the degree of forest disturbance to the global carbon cycle and climate. Although tropical montane forests are an important part of tropical forest ecosystems (ca. 8 %, elevation > 1000 m a.s.l.), there are still significant knowledge gaps regarding the carbon dynamics and stocks of these forests, and how these differ between early (ES) and late successional (LS) stages. This study examines the carbon (C) stock, relative growth rate (RGR) and net primary production (NPP) of ES and LS forest stands in an Afromontane tropical rainforest using data from inventories of quantitatively important ecosystem compartments in fifteen 0.5 ha plots in Nyungwe National Park in Rwanda. The total C stock was 35 % larger in LS compared to ES plots due to significantly larger above-ground biomass (AGB; 185 and 76 Mg C ha-1 in LS and ES plots), while the soil and root C stock (down to 45 cm depth in the mineral soil) did not significantly differ between the two successional stages (178 and 204 Mg C ha-1 in LS and ES plots). The main reasons for the difference in AGB were that ES trees had significantly lower stature and wood density compared to LS trees. However, ES and LS stands had similar total NPP (canopy, wood and roots of all plots ˜ 9.4 Mg C ha-1) due to counterbalancing effects of differences in AGB (higher in LS stands) and RGR (higher in ES stands). The AGB in the LS plots was considerably higher than the average value reported for old-growth tropical montane forest of south-east Asia and Central and South America at similar elevations and temperatures, and of the same magnitude as in tropical lowland forest of these regions. The results of this study highlight the importance of accounting for disturbance regimes and differences in wood density and allometry of

Litter and dead wood dynamics in ponderosa pine forests along a 160-year chronosequence.

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Hall, S A; Burke, I C; Hobbs, N T

2006-12-01

Disturbances such as fire play a key role in controlling ecosystem structure. In fire-prone forests, organic detritus comprises a large pool of carbon and can control the frequency and intensity of fire. The ponderosa pine forests of the Colorado Front Range, USA, where fire has been suppressed for a century, provide an ideal system for studying the long-term dynamics of detrital pools. Our objectives were (1) to quantify the long-term temporal dynamics of detrital pools; and (2) to determine to what extent present stand structure, topography, and soils constrain these dynamics. We collected data on downed dead wood, litter, duff (partially decomposed litter on the forest floor), stand structure, topographic position, and soils for 31 sites along a 160-year chronosequence. We developed a compartment model and parameterized it to describe the temporal trends in the detrital pools. We then developed four sets of statistical models, quantifying the hypothesized relationship between pool size and (1) stand structure, (2) topography, (3) soils variables, and (4) time since fire. We contrasted how much support each hypothesis had in the data using Akaike's Information Criterion (AIC). Time since fire explained 39-80% of the variability in dead wood of different size classes. Pool size increased to a peak as material killed by the fire fell, then decomposed rapidly to a minimum (61-85 years after fire for the different pools). It then increased, presumably as new detritus was produced by the regenerating stand. Litter was most strongly related to canopy cover (r2 = 77%), suggesting that litter fall, rather than decomposition, controls its dynamics. The temporal dynamics of duff were the hardest to predict. Detrital pool sizes were more strongly related to time since fire than to environmental variables. Woody debris peak-to-minimum time was 46-67 years, overlapping the range of historical fire return intervals (1 to > 100 years). Fires may therefore have burned under a

Average Stand Age from Forest Inventory Plots Does Not Describe Historical Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America.

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Jens T Stevens

Full Text Available Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the "stand age" variable from the US Forest Service Forest Inventory and Analysis (FIA program reflects the timing of historical high-severity (i.e. stand-replacing fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1 the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age basal area in 58% of plots analyzed and more than 30% of pre-stand age basal area in 32% of plots, and 2 recruitment events are not necessarily related to high-severity fire occurrence. Because the FIA stand age variable is estimated from a sample of tree ages within the tree size class containing a plurality of canopy trees in the plot, it does not necessarily include the oldest trees, especially in uneven-aged stands. Thus, the FIA stand age variable does not indicate whether the trees in the predominant size class established in response to severe fire, or established during the absence of fire. FIA stand age was not designed to measure the time since a stand-replacing disturbance. Quantification of historical "mixed-severity" fire regimes must be explicit about the spatial scale of high-severity fire effects, which is not possible using FIA stand age data.

Average Stand Age from Forest Inventory Plots Does Not Describe Historical Fire Regimes in Ponderosa Pine and Mixed-Conifer Forests of Western North America.

Science.gov (United States)

Stevens, Jens T; Safford, Hugh D; North, Malcolm P; Fried, Jeremy S; Gray, Andrew N; Brown, Peter M; Dolanc, Christopher R; Dobrowski, Solomon Z; Falk, Donald A; Farris, Calvin A; Franklin, Jerry F; Fulé, Peter Z; Hagmann, R Keala; Knapp, Eric E; Miller, Jay D; Smith, Douglas F; Swetnam, Thomas W; Taylor, Alan H

Quantifying historical fire regimes provides important information for managing contemporary forests. Historical fire frequency and severity can be estimated using several methods; each method has strengths and weaknesses and presents challenges for interpretation and verification. Recent efforts to quantify the timing of historical high-severity fire events in forests of western North America have assumed that the "stand age" variable from the US Forest Service Forest Inventory and Analysis (FIA) program reflects the timing of historical high-severity (i.e. stand-replacing) fire in ponderosa pine and mixed-conifer forests. To test this assumption, we re-analyze the dataset used in a previous analysis, and compare information from fire history records with information from co-located FIA plots. We demonstrate that 1) the FIA stand age variable does not reflect the large range of individual tree ages in the FIA plots: older trees comprised more than 10% of pre-stand age basal area in 58% of plots analyzed and more than 30% of pre-stand age basal area in 32% of plots, and 2) recruitment events are not necessarily related to high-severity fire occurrence. Because the FIA stand age variable is estimated from a sample of tree ages within the tree size class containing a plurality of canopy trees in the plot, it does not necessarily include the oldest trees, especially in uneven-aged stands. Thus, the FIA stand age variable does not indicate whether the trees in the predominant size class established in response to severe fire, or established during the absence of fire. FIA stand age was not designed to measure the time since a stand-replacing disturbance. Quantification of historical "mixed-severity" fire regimes must be explicit about the spatial scale of high-severity fire effects, which is not possible using FIA stand age data.

Living and Dead Aboveground Biomass in Mediterranean Forests: Evidence of Old-Growth Traits in a Quercus pubescens Willd. s.l. Stand

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Emilio Badalamenti

2017-05-01

Full Text Available For a long time, human impact has deeply simplified most of the forest ecosystems of the Mediterranean Basin. Here, forests have seldom had the chance to naturally develop a complex and multilayered structure, to host large and old trees and rich biological communities, approaching old-growth conditions. Also for this reason, limited information is currently available about Mediterranean old-growth forests, particularly with regard to deadwood. The main aim of this work is to help fill this critical knowledge gap. In Sicily (Italy, we identified a Quercus pubescens forest that seemed to show some typical old-growth features. Total living volume (360 m3 ha−1 and basal area (34 m2 ha−1 were, respectively, about 6 and 3 times higher than the averages recorded in the regional forest inventory for this forest type. Deadwood was particularly abundant, exceeding the threshold of 30 m3 ha−1, mainly represented by lying dead elements. Dead to live wood ratio reached 9%, a value close to the threshold of 10% considered for Mediterranean old-growth forests. As the investigated forest showed some typical old-growth traits, it deserves to be fully protected and could be a permanent monitoring area for studying deadwood and stand dynamics in mature Mediterranean stands.

Unravelling the importance of forest age stand and forest structure driving microbiological soil properties, enzymatic activities and soil nutrients content in Mediterranean Spanish black pine(Pinus nigra Ar. ssp. salzmannii) Forest.

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Lucas-Borja, M E; Hedo, J; Cerdá, A; Candel-Pérez, D; Viñegla, B

2016-08-15

This study aimed to investigate the effects that stand age and forest structure have on microbiological soil properties, enzymatic activities and nutrient content. Thirty forest compartments were randomly selected at the Palancares y Agregados managed forest area (Spain), supporting forest stands of five ages; from 100 to 80years old to compartments with trees that were 19-1years old. Forest area ranging from 80 to 120years old and without forest intervention was selected as the control. We measured different soil enzymatic activities, soil respiration and nutrient content (P, K, Na, Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Pb and Ca) in the top cm of 10 mineral soils in each compartment. Results showed that the lowest forest stand age and the forest structure created by management presented lower values of organic matter, soil moisture, water holding capacity and litterfall and higher values of C/N ratio in comparison with the highest forest stand age and the related forest structure, which generated differences in soil respiration and soil enzyme activities. The forest structure created by no forest management (control plot) presented the highest enzymatic activities, soil respiration, NH4(+) and NO3(-). Results did not show a clear trend in nutrient content comparing all the experimental areas. Finally, the multivariate PCA analysis clearly clustered three differentiated groups: Control plot; from 100 to 40years old and from 39 to 1year old. Our results suggest that the control plot has better soil quality and that extreme forest stand ages (100-80 and 19-1years old) and the associated forest structure generates differences in soil parameters but not in soil nutrient content. Copyright © 2016 Elsevier B.V. All rights reserved.

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

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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.

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.

Sapflow-Based Stand Transpiration in a Semiarid Natural Oak Forest on China’s Loess Plateau

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Mei-Jie Yan

2016-10-01

Full Text Available The semi-arid region of China’s Loess Plateau is characterized by fragile ecosystems and a shortage of water resources. The major natural forest type in this region is the secondary forest with the flora dominated by the Liaodong oak (Quercus liaotungensis Koidz.. To understand its transpiration water use in relation to environmental factors, we applied Granier-type thermal dissipation probes to monitor stem sap flows of 21 sample trees, representing different classes of diameter at breast height in a permanent plot. The stem- and stand-scale transpiration values during the 2008–2010 growing seasons were estimated using measurements of sap flux densities and corresponding sapwood areas. The dominant factors affecting stand-scale transpiration varied with time scales. Daily stand transpiration correlated with daily solar radiation and daytime average vapor pressure deficit. Seasonal and interannual changes in stand transpiration were closely related to leaf area index (LAI values. No obvious relationship was observed between monthly stand transpiration and soil moisture or precipitation during the period, probably as a result of both the hysteretic effect of precipitation on transpiration, and changes in LAI throughout the growing season. Stand transpiration during the three growing seasons ranged from 75 to 106 mm, representing low to normal values for the semi-arid forest. The proportion of transpiration by oak trees in the stand was stable ranging from 60% to 66% and corresponded to their basal area proportion of approximately 59%. The results suggest that the natural forest consisting mainly of oak trees is in a formal stage of forest development that maintains a normal magnitude of annual water consumption.

An experimental test of the causes of forest growth decline with stand age.

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Michael G. Ryan; Dan Binkley; James H. Fownes; Christian Giardina; Randy S. Senock

2004-01-01

The decline in aboveground wood production after canopy closure in even-aged forest stands is a common pattern in forests, but clear evidence for the mechanism causing the decline is lacking. The problem is fundamental to forest biology, commercial forestry (the decline sets the rotation age), and to carbon storage in forests. We tested three hypotheses...

Dynamics of forest ecosystems regenerated on burned and harvested areas in mountain regions of Siberia: characteristics of biological diversity, structure and productivity

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I. M. Danilin

2016-12-01

Full Text Available Complex estimation of forest ecosystems dynamics based on detailing characteristics of structure, growth and productivity of the stands and describing general geographical and biological management options for preserving their biodiversity and sustaining stability are discussed in the paper by describing examples of tree stands restored on burned and logged areas in mountain regions of Siberia. On vast areas in Siberia, characterized as sub-boreal, subarid and with a strongly continental climate, forests grow on seasonally frozen soils and in many cases are surrounded by vast steppe and forest-steppe areas and uplands. Developing criteria for sustainability of mountain forest ecosystems is necessary for forest resource management and conservation. It is therefore important to obtain complex biometric characteristics on forest stands and landscapes and to thoroughly study their structure, biological diversity and productivity. Morphometric methods, Weibull simulation and allometric equations were used to determine the dimensional hierarchies of coenopopulation individuals. Structure and productivity of the aboveground stand components were also studied.

Modelling canopy fuel and forest stand variables and characterizing the influence of thinning in the stand structure using airborne LiDAR

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A. Hevia

2016-02-01

Full Text Available Forest fires are a major threat in NW Spain. The importance and frequency of these events in the area suggests the need for fuel management programs to reduce the spread and severity of forest fires. Thinning treatments can contribute for fire risk reduction, because they cut off the horizontal continuity of forest fuels. Besides, it is necessary to conduct a fire risk management based on the knowledge of fuel allocation, since fire behaviour and fire spread study is dependent on the spatial factor. Therefore, mapping fuel for different silvicultural scenarios is essential. Modelling forest variables and forest structure parameters from LiDAR technology is the starting point for developing spatially explicit maps. This is essential in the generation of fuel maps since field measurements of canopy fuel variables is not feasible. In the present study, we evaluated the potential of LiDAR technology to estimate canopy fuel variables and other stand variables, as well as to identify structural differences between silvicultural managed and unmanaged P. pinaster Ait. stands. Independent variables (LiDAR metrics of greater explanatory significance were identified and regression analyses indicated strong relationships between those and field-derived variables (R2 varied between 0.86 and 0.97. Significant differences were found in some LiDAR metrics when compared thinned and unthinned stands. Results showed that LiDAR technology allows to model canopy fuel and stand variables with high precision in this species, and provides useful information for identifying areas with and without silvicultural management.

Neural network modelling of rainfall interception in four different forest stands

OpenAIRE

Ibrahim Yurtseven; Mustafa Zengin

2013-01-01

The objective of this study is to reveal whether it is possible to predict rainfall, throughfall and stemflow in forest ecosystems with less effort, using several measurements of rainfall interception (hereafter interception) and an artificial neural network based linear regression model (ANN model). To this end, the Kerpe Research Forest in the province of Kocaeli, which houses stands of mixed deciduous-broadleaf forest (Castanea sativa Mill., Fagus orientalis Lipsky, Quercus spp.), black pi...

Post-disturbance plant community dynamics following a rare natural-origin fire in a Tsuga canadensis forest.

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Bryan D Murray

Full Text Available Opportunities to directly study infrequent forest disturbance events often lead to valuable information about vegetation dynamics. In mesic temperate forests of North America, stand-replacing crown fire occurs infrequently, with a return interval of 2000-3000 years. Rare chance events, however, may have profound impacts on the developmental trajectories of forest ecosystems. For example, it has been postulated that stand-replacing fire may have been an important factor in the establishment of eastern hemlock (Tsuga canadensis stands in the northern Great Lakes region. Nevertheless, experimental evidence linking hemlock regeneration to non-anthropogenic fire is limited. To clarify this potential relationship, we monitored vegetation dynamics following a rare lightning-origin crown fire in a Wisconsin hemlock-hardwood forest. We also studied vegetation in bulldozer-created fire breaks and adjacent undisturbed forest. Our results indicate that hemlock establishment was rare in the burned area but moderately common in the scarified bulldozer lines compared to the reference area. Early-successional, non-arboreal species including Rubus spp., Vaccinium angustifolium, sedges (Carex spp., grasses, Epilobium ciliatum, and Pteridium aquilinium were the most abundant post-fire species. Collectively, our results suggest that competing vegetation and moisture stress resulting from drought may reduce the efficacy of scarification treatments as well as the usefulness of fire for preparing a suitable seedbed for hemlock. The increasing prevalence of growing-season drought suggests that silvicultural strategies based on historic disturbance regimes may need to be reevaluated for mesic species.

Dynamics of Connecticut hemlock stands

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Jeffrey S. Ward; David M. Smith

2000-01-01

The stand dynamics and production of two one-acre plots of eastern hemlock (Tsuga canadensis L) in Connecticut have been followed for more than six decades. Data were recorded for all individual trees. One plot (Saltonstall) was established in 1924 after the removal of a hardwood overstory. This stand had a nearly pure, almost fully closed understory...

Coupled effects of wind-storms and drought on tree mortality across 115 forest stands from the Western Alps and the Jura mountains.

Science.gov (United States)

Csilléry, Katalin; Kunstler, Georges; Courbaud, Benoît; Allard, Denis; Lassègues, Pierre; Haslinger, Klaus; Gardiner, Barry

2017-12-01

Damage due to wind-storms and droughts is increasing in many temperate forests, yet little is known about the long-term roles of these key climatic factors in forest dynamics and in the carbon budget. The objective of this study was to estimate individual and coupled effects of droughts and wind-storms on adult tree mortality across a 31-year period in 115 managed, mixed coniferous forest stands from the Western Alps and the Jura mountains. For each stand, yearly mortality was inferred from management records, yearly drought from interpolated fields of monthly temperature, precipitation and soil water holding capacity, and wind-storms from interpolated fields of daily maximum wind speed. We performed a thorough model selection based on a leave-one-out cross-validation of the time series. We compared different critical wind speeds (CWSs) for damage, wind-storm, and stand variables and statistical models. We found that a model including stand characteristics, drought, and storm strength using a CWS of 25 ms -1 performed the best across most stands. Using this best model, we found that drought increased damage risk only in the most southerly forests, and its effect is generally maintained for up to 2 years. Storm strength increased damage risk in all forests in a relatively uniform way. In some stands, we found positive interaction between drought and storm strength most likely because drought weakens trees, and they became more prone to stem breakage under wind-loading. In other stands, we found negative interaction between drought and storm strength, where excessive rain likely leads to soil water saturation making trees more susceptible to overturning in a wind-storm. Our results stress that temporal data are essential to make valid inferences about ecological impacts of disturbance events, and that making inferences about disturbance agents separately can be of limited validity. Under projected future climatic conditions, the direction and strength of these

The role of forest stand density in controlling soil erosion: implications to sediment-related disasters in Japan.

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Razafindrabe, Bam H N; He, Bin; Inoue, Shoji; Ezaki, Tsugio; Shaw, Rajib

2010-01-01

The role of forest stand density in controlling soil erosion was investigated in Ehime Prefecture, Japan. The main objective was to compare soil erosion under different forest conditions including forest type, species composition, and stand density as influenced by thinning operations. Relative yield index (Ry) was used as an indicator of stand density to reflect the degree of management operations in the watershed. Eleven treatments were established based on the above forest conditions. Soil loss was collected in each of the 11 treatments after each rainfall event for a period of 1 year. The paper presents summary data on soil loss as affected by forest conditions and rainfall patterns. Findings showed that an appropriate forest management operation, which can be insured by stand density control, is needed to reduce soil loss. The present study plays an important role in clarifying technical processes related to soil erosion, while it helps linking these elements to current Japanese forestry issues and bringing new inputs to reducing sediment-related disasters in Japan.

Influence of stocking, site quality, stand age, low-severity canopy disturbance, and forest composition on sub-boreal aspen mixedwood carbon stocks

Science.gov (United States)

Reinikainen, Michael; D’Amato, Anthony W.; Bradford, John B.; Fraver, Shawn

2014-01-01

Low-severity canopy disturbance presumably influences forest carbon dynamics during the course of stand development, yet the topic has received relatively little attention. This is surprising because of the frequent occurrence of such events and the potential for both the severity and frequency of disturbances to increase as a result of climate change. We investigated the impacts of low-severity canopy disturbance and average insect defoliation on forest carbon stocks and rates of carbon sequestration in mature aspen mixedwood forests of varying stand age (ranging from 61 to 85 years), overstory composition, stocking level, and site quality. Stocking level and site quality positively affected the average annual aboveground tree carbon increment (CAAI), while stocking level, site quality, and stand age positively affected tree carbon stocks (CTREE) and total ecosystem carbon stocks (CTOTAL). Cumulative canopy disturbance (DIST) was reconstructed using dendroecological methods over a 29-year period. DIST was negatively and significantly related to soil carbon (CSOIL), and it was negatively, albeit marginally, related to CTOTAL. Minima in the annual aboveground carbon increment of trees (CAI) occurred at sites during defoliation of aspen (Populus tremuloides Michx.) by forest tent caterpillar (Malacosoma disstria Hubner), and minima were more extreme at sites dominated by trembling aspen than sites mixed with conifers. At sites defoliated by forest tent caterpillar in the early 2000s, increased sequestration by the softwood component (Abies balsamea (L.) Mill. and Picea glauca (Moench) Voss) compensated for overall decreases in CAI by 17% on average. These results underscore the importance of accounting for low-severity canopy disturbance events when developing regional forest carbon models and argue for the restoration and maintenance of historically important conifer species within aspen mixedwoods to enhance stand-level resilience to disturbance agents and maintain

Reducing uncertainty for estimating forest carbon stocks and dynamics using integrated remote sensing, forest inventory and process-based modeling

Science.gov (United States)

Poulter, B.; Ciais, P.; Joetzjer, E.; Maignan, F.; Luyssaert, S.; Barichivich, J.

2015-12-01

Accurately estimating forest biomass and forest carbon dynamics requires new integrated remote sensing, forest inventory, and carbon cycle modeling approaches. Presently, there is an increasing and urgent need to reduce forest biomass uncertainty in order to meet the requirements of carbon mitigation treaties, such as Reducing Emissions from Deforestation and forest Degradation (REDD+). Here we describe a new parameterization and assimilation methodology used to estimate tropical forest biomass using the ORCHIDEE-CAN dynamic global vegetation model. ORCHIDEE-CAN simulates carbon uptake and allocation to individual trees using a mechanistic representation of photosynthesis, respiration and other first-order processes. The model is first parameterized using forest inventory data to constrain background mortality rates, i.e., self-thinning, and productivity. Satellite remote sensing data for forest structure, i.e., canopy height, is used to constrain simulated forest stand conditions using a look-up table approach to match canopy height distributions. The resulting forest biomass estimates are provided for spatial grids that match REDD+ project boundaries and aim to provide carbon estimates for the criteria described in the IPCC Good Practice Guidelines Tier 3 category. With the increasing availability of forest structure variables derived from high-resolution LIDAR, RADAR, and optical imagery, new methodologies and applications with process-based carbon cycle models are becoming more readily available to inform land management.

Object-based semi-automatic approach for forest structure characterization using lidar data in heterogeneous Pinus sylvestris stands

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C. Pascual; A. Garcia-Abril; L.G. Garcia-Montero; S. Martin-Fernandez; W.B. Cohen

2008-01-01

In this paper, we present a two-stage approach for characterizing the structure of Pinus sylvestris L. stands in forests of central Spain. The first stage was to delimit forest stands using eCognition and a digital canopy height model (DCHM) derived from lidar data. The polygons were then clustered into forest structure types based on the DCHM data...

Features of secondary birch young stands in low mountain Pokuttya (Ukrainian Carpathian Mts. )

OpenAIRE

MILEVSKAYA S.Y.

2015-01-01

Forest landscapes of the region during the last 3–5 centuries undergone the profound anthropogenic transformation. Secondary young stands occupy 25% of the total forest area. The problem of derivatives is particularly relevant for the modern forest typology in the Carpathian region. It requires the reflection in its dynamic trends shaping the stands, especially mixed young stands. The aim of our study consisted in getting the knowledge of the structural features of the secondary phytocoenosis...

Gap Dynamics and Structure of Two Old-Growth Beech Forest Remnants in Slovenia

Science.gov (United States)

Rugani, Tihomir; Diaci, Jurij; Hladnik, David

2013-01-01

Context Due to a long history of intensive forest exploitation, few European beech (Fagus sylvatica L.) old-growth forests have been preserved in Europe. Material and Methods We studied two beech forest reserves in southern Slovenia. We examined the structural characteristics of the two forest reserves based on data from sample plots and complete inventory obtained from four previous forest management plans. To gain a better understanding of disturbance dynamics, we used aerial imagery to study the characteristics of canopy gaps over an 11-year period in the Kopa forest reserve and a 20-year period in the Gorjanci forest reserve. Results The results suggest that these forests are structurally heterogeneous over small spatial scales. Gap size analysis showed that gaps smaller than 500 m2 are the dominant driving force of stand development. The percentage of forest area in canopy gaps ranged from 3.2 to 4.5% in the Kopa forest reserve and from 9.1 to 10.6% in the Gorjanci forest reserve. These forests exhibit relatively high annual rates of coverage by newly established (0.15 and 0.25%) and closed (0.08 and 0.16%) canopy gaps. New gap formation is dependant on senescent trees located throughout the reserve. Conclusion We conclude that these stands are not even-sized, but rather unevenly structured. This is due to the fact that the disturbance regime is characterized by low intensity, small-scale disturbances. PMID:23308115

Carbon dynamics after forest harvest in Central Siberia: the ZOTTO footprint area

Science.gov (United States)

Panov, Alexey; Zrazhevskaya, Galina; Shibistova, Olga; Onuchin, Alexander; Heimann, Martin

2013-04-01

Temperate and boreal forests of the Northern Hemisphere have been recognized as important carbon sinks. Accurate calculation of forest carbon budget and estimation of the temporal variations of forest net carbon fluxes are important topics to elucidate the ''missing sink'' question and follow up the changing carbon dynamics in forests. In the frame of the ongoing Russian-German partner project the Zotino Tall Tower Observatory (ZOTTO; www.zottoproject.org) a unique international research platform for large-scale climatic observations is operational about 20 km west of the Yenisei river (60.8°N; 89.35°E). The data of the ongoing greenhouse gas and aerosol measurements at the tall tower are used in atmospheric inversions studies to infer the distribution of carbon sinks and sources over the whole Northern Eurasia. The tall tower footprint area estimates of carbon stocks and fluxes are highly demanded for bottom-up validation of inversion estimates. The ZOTTO site lies in a vast region of forests and wetlands, still relatively undisturbed by anthropogenic influences, but a moderate human impact on vegetation, represented mainly by logging activities, becomes essential. Therefore, accurate estimates of carbon pools in vegetation and soil following harvesting are essential to inversion studies for ZOTTO and critical to predictions of both local ecosystem sustainability and global C exchange with the atmosphere. We present our investigation of carbon dynamics after forest harvest in the tall tower footprint area (~1000 km2). The changes in C pools and annual sequestration were quantified among several clear-cut lichen pine (Pinus sylvestris Lamb.) stands representing various stages of secondary succession with a "space-for-time substitution" technique. When viewed as a chronosequence, these stands represent snapshots showing how the effects of logging may propagate through time. The study concluded that ecosystems during the first 15 yrs after forest harvest become C

Dynamic anthropogenic edge effects on the distribution and diversity of fungi in fragmented old-growth forests.

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Ruete, Alejandro; Snäll, Tord; Jönsson, Mari

2016-07-01

Diversity patterns and dynamics at forest edges are not well understood. We disentangle the relative importance of edge-effect variables on spatio-temporal patterns in species richness and occupancy of deadwood-dwelling fungi in fragmented old-growth forests. We related richness and log occupancy by 10 old-growth forest indicator fungi and by two common fungi to log conditions in natural and anthropogenic edge habitats of 31 old-growth Picea abies forest stands in central Sweden. We compared edge-to-interior gradients (100 m) to the forest interior (beyond 100 m), and we analyzed stand-level changes after 10 yr. Both richness and occupancy of logs by indicator species was negatively related to adjacent young clear-cut edges, but this effect decreased with increasing clear-cut age. The occupancy of logs by indicator species also increased with increasing distance to the natural edges. In contrast, the occupancy of logs by common species was positively related or unrelated to distance to clear-cut edges regardless of the edge age, and this was partly explained by fungal specificity to substrate quality. Stand-level mean richness and mean occupancy of logs did not change for indicator or common species over a decade. By illustrating the importance of spatial and temporal dimensions of edge effects, we extend the general understanding of the distribution and diversity of substrate-confined fungi in fragmented old-growth forests. Our results highlight the importance of longer forest rotation times adjacent to small protected areas and forest set-asides, where it may take more than 50 yr for indicator species richness levels to recover to occupancy levels observed in the forest interior. Also, non-simultaneous clear-cutting of surrounding productive forests in a way that reduces the edge effect over time (i.e., dynamic buffers) may increase the effective core area of small forest set-asides and improve their performance on protecting species of special concern for

Modelling Variable Fire Severity in Boreal Forests: Effects of Fire Intensity and Stand Structure.

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Miquelajauregui, Yosune; Cumming, Steven G; Gauthier, Sylvie

2016-01-01

It is becoming clear that fires in boreal forests are not uniformly stand-replacing. On the contrary, marked variation in fire severity, measured as tree mortality, has been found both within and among individual fires. It is important to understand the conditions under which this variation can arise. We integrated forest sample plot data, tree allometries and historical forest fire records within a diameter class-structured model of 1.0 ha patches of mono-specific black spruce and jack pine stands in northern Québec, Canada. The model accounts for crown fire initiation and vertical spread into the canopy. It uses empirical relations between fire intensity, scorch height, the percent of crown scorched and tree mortality to simulate fire severity, specifically the percent reduction in patch basal area due to fire-caused mortality. A random forest and a regression tree analysis of a large random sample of simulated fires were used to test for an effect of fireline intensity, stand structure, species composition and pyrogeographic regions on resultant severity. Severity increased with intensity and was lower for jack pine stands. The proportion of simulated fires that burned at high severity (e.g. >75% reduction in patch basal area) was 0.80 for black spruce and 0.11 for jack pine. We identified thresholds in intensity below which there was a marked sensitivity of simulated fire severity to stand structure, and to interactions between intensity and structure. We found no evidence for a residual effect of pyrogeographic region on simulated severity, after the effects of stand structure and species composition were accounted for. The model presented here was able to produce variation in fire severity under a range of fire intensity conditions. This suggests that variation in stand structure is one of the factors causing the observed variation in boreal fire severity.

Dynamics models and modeling of tree stand development

Directory of Open Access Journals (Sweden)

M. V. Rogozin

2015-04-01

Full Text Available Brief analysis of scientific works in Russia and in the CIS over the past 100 years. Logical and mathematical models consider the conceptual and show some of the results of their verification. It was found that the models include different laws and the parameters, the sum of which allows you to divide them into four categories: models of static states, development models, models of care for the natural forest and models of cultivation. Each category has fulfilled and fulfills its tasks in economic management. Thus, the model states in statics (table traverse growth played a prominent role in figuring out what may be the most productive (full stands in different regions of the country. However, they do not answer the question of what the initial states lead to the production of complete stands. In a study of the growth of stands used system analysis, and it is observed dominance of works studying static state, snatched from the biological time. Therefore, the real drama of the growth of stands remained almost unexplored. It is no accident there were «chrono-forestry» «plantation forestry» and even «non-traditional forestry», where there is a strong case of a number of new concepts of development stands. That is quite in keeping with Kuhn (Kuhn, 2009 in the forestry crisis began – there were alternative theories and coexist conflicting scientific schools. To develop models of stand development, it is proposed to use a well-known method of repeated observations within 10–20 years, in conjunction with the explanation of the history of the initial density. It mounted on the basis of studying the dynamics of its indicators: the trunk, crown overlap coefficient, the sum of volumes of all crowns and the relative length of the crown. According to these indicators, the researcher selects natural series of development stands with the same initial density. As a theoretical basis for the models it is possible to postulate the general properties of

Effects of stand composition and thinning in mixed-species forests : a modeling approach applied to Douglas-fir and beech

NARCIS (Netherlands)

Bartelink, H.H.

2000-01-01

Models estimating growth and yield of forest stands provide important tools for forest management. Pure stands have been modeled extensively and successfully for decades; however, relatively few models for mixed-species stands have been developed. A spatially explicit, mechanistic model (COMMIX) is

Changes of forest stands vulnerability to future wind damage resulting from different management methods

DEFF Research Database (Denmark)

Panferov, O.; Sogachev, Andrey; Ahrends, B.

2010-01-01

The structure of forests stands changes continuously as a result of forest growth and both natural and anthropogenic disturbances like windthrow or management activities – planting/cutting of trees. These structure changes can stabilize or destabilize forest stands in terms of their resistance...... to wind damage. The driving force behind the damage is the climate, but the magnitude and sign of resulting effect depend on tree species, management method and soil conditions. The projected increasing frequency of weather extremes in the whole and severe storms in particular might produce wide area...... damage in European forest ecosystems during the 21st century. To assess the possible wind damage and stabilization/destabilization effects of forest management a number of numeric experiments are carried out for the region of Solling, Germany. The coupled small-scale process-based model combining Brook90...

Information system of forest growth and productivity by site quality type and elements of forest

Science.gov (United States)

Khlyustov, V.

2012-04-01

Information system of forest growth and productivity by site quality type and elements of forest V.K. Khlustov Head of the Forestry Department of Russian State Agrarian University named after K.A.Timiryazev doctor of agricultural sciences, professor The efficiency of forest management can be improved substantially by development and introduction of principally new models of forest growth and productivity dynamics based on regionalized site specific parameters. Therefore an innovative information system was developed. It describes the current state and gives a forecast for forest stand parameters: growth, structure, commercial and biological productivity depend on type of site quality. In contrast to existing yield tables, the new system has environmental basis: site quality type. The information system contains set of multivariate statistical models and can work at the level of individual trees or at the stand level. The system provides a graphical visualization, as well as export of the emulation results. The System is able to calculate detailed description of any forest stand based on five initial indicators: site quality type, site index, stocking, composition, and tree age by elements of the forest. The results of the model run are following parameters: average diameter and height, top height, number of trees, basal area, growing stock (total, commercial with distribution by size, firewood and residuals), live biomass (stem, bark, branches, foliage). The system also provides the distribution of mentioned above forest stand parameters by tree diameter classes. To predict the future forest stand dynamics the system require in addition the time slot only. Full set of forest parameters mention above will be provided by the System. The most conservative initial parameters (site quality type and site index) can be kept in the form of geo referenced polygons. In this case the system would need only 3 dynamic initial parameters (stocking, composition and age) to

Using a stand-level model to predict light absorption in stands with vertically and horizontally heterogeneous canopies

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David I Forrester

2014-09-01

Full Text Available Background Forest ecosystem functioning is strongly influenced by the absorption of photosynthetically active radiation (APAR, and therefore, accurate predictions of APAR are critical for many process-based forest growth models. The Lambert-Beer law can be applied to estimate APAR for simple homogeneous canopies composed of one layer, one species, and no canopy gaps. However, the vertical and horizontal structure of forest canopies is rarely homogeneous. Detailed tree-level models can account for this heterogeneity but these often have high input and computational demands and work on finer temporal and spatial resolutions than required by stand-level growth models. The aim of this study was to test a stand-level light absorption model that can estimate APAR by individual species in mixed-species and multi-layered stands with any degree of canopy openness including open-grown trees to closed canopies. Methods The stand-level model was compared with a detailed tree-level model that has already been tested in mixed-species stands using empirical data. Both models were parameterised for five different forests, including a wide range of species compositions, species proportions, stand densities, crown architectures and canopy structures. Results The stand-level model performed well in all stands except in the stand where extinction coefficients were unusually variable and it appears unlikely that APAR could be predicted in such stands using (tree- or stand-level models that do not allow individuals of a given species to have different extinction coefficients, leaf-area density or analogous parameters. Conclusion This model is parameterised with species-specific information about extinction coefficients and mean crown length, diameter, height and leaf area. It could be used to examine light dynamics in complex canopies and in stand-level growth models.

Tree dynamics in canopy gaps in old-growth forests of Nothofagus pumilio in Southern Chile

NARCIS (Netherlands)

Fajardo, Alex; Graaf, de N.R.

2004-01-01

The gap dynamics of two Nothofagus pumilio (lenga) stands have been investigated. We evaluated and compared tree diameter distributions, spatial patterns, tree fall and gap characteristics and regeneration responses in gaps in two old-growth forests of Nothofagus pumilio in Southern Chile

Temporal changes in radiocesium deposition in various forest stands following the Fukushima Dai-ichi Nuclear Power Plant accident.

Science.gov (United States)

Kato, Hiroaki; Onda, Yuichi; Hisadome, Keigo; Loffredo, Nicolas; Kawamori, Ayumi

2017-01-01

In this study, we investigated the transfer of canopy-intercepted radiocesium to the forest floor following the Fukushima Dai-ichi Nuclear Power Plant accident. The 137 Cs content of throughfall, stemflow, and litterfall were monitored in two coniferous stands (plantations of Japanese cedar) and a deciduous mixed broad-leaved forest stand (oak with red pine) from July 2011 to December 2012. The forest floor of cedar stands had received higher levels of additional 137 Cs deposition compared with the mixed broad-leaved stand during the sampling period. The cumulative 137 Cs deposition during the study period was 119 kBq m -2 for the mature cedar stand, 105 kBq m -2 for the young cedar stand, and 41.5 kBq m -2 for the broad-leaved stand. The deposition of 137 Cs to the forest floor occurred mainly in throughfall during the first rainy season, from July to September 2011 (<200 d after the initial fallout); thereafter, the transfer of 137 Cs from the canopy to forest floor occurred mainly through litterfall. A double exponential field-loss model, which was used to simulate the removal of 137 Cs from canopies, was the best fit for the temporal changes in the canopy 137 Cs inventory. Copyright © 2015 Elsevier Ltd. All rights reserved.

Forest structure and plant diversity in maritime pine (Pinus pinaster Ait.) stands in central Spain

Energy Technology Data Exchange (ETDEWEB)

Osorio, L. F.; Bravo, F.; Zaldivar, P.; Pando, V.

2009-07-01

The relationship between forest structure and plant diversity in Mediterranean Maritime pine stands (Pinus pinaster Ait.) in the Iberian Range (Spain) was studied. Forty eight stands were sampled. In each, a circular plot (15 m radius) and a transect (25*1 m{sup 2}) were established to estimate stand variables and record presence and abundance of vascular species respectively. Canonical correlation analysis (CCA), simple correlations and multiple stepwise linear regressions were used to explore the relationship between plant diversity and forest structure. Correlation between diversity measurements and stand variables is very weak, but significant correlations were found when evaluating each set of variables separately. Presence and cover of some species (for instance, Veronica arvensis L. or Micropyrum tenellum (L.) Link) is correlated with stand variables; however, determination coefficients found in step-by-step regression are not significant. (Author) 34 refs.

Stand and within-stand factors influencing Golden-winged Warbler use of regenerating stands in the central Appalachian Mountains

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Marja H. Bakermans

2015-06-01

Full Text Available The Golden-winged Warbler (Vermivora chrysoptera is currently being considered for protected status under the U.S. Endangered Species Act. The creation of breeding habitat in the Appalachian Mountains is considered a conservation priority for this songbird, which is dependent on extensively forested landscapes with adequate availability of young forest. We modeled abundance of Golden-winged Warbler males in regenerating harvested forest stands that were 0-17 years postharvest at both mid-Appalachian and northeast Pennsylvania regional scales using stand and within-stand characteristics of 222 regenerating stands, 2010-2011. Variables that were most influential at the mid-Appalachian scale were different than those in the northeast region. Across the mid-Appalachian ecoregion, the proportion of young forest cover, i.e., shrub/scrub cover, within 1 km of regenerating stands best explained abundance of Golden-winged Warblers. Golden-winged Warbler response was best explained by a concave quadratic relationship in which abundance was highest with 5-15% land in young forest cover. We also found evidence that the amount of herbaceous cover, i.e., the amount of grasses and forbs, within a regenerating stand positively influenced abundance of Golden-winged Warblers. In northeastern Pennsylvania, where young forest cover is found in high proportions, the distance to the nearest regenerating stand best explained variation in abundance of Golden-winged Warblers. Abundance of Golden-winged Warblers was 1500 m away. When modeling within-stand features in the northeast region, many of the models were closely ranked, indicating that multiple variables likely explained Golden-winged Warbler response to within-stand conditions. Based on our findings, we have proposed several management guidelines for land managers interested in creating breeding habitat for Golden-winged Warblers using commercial timber operations. For example, we recommend when managing for

Dynamics of secondary forests

NARCIS (Netherlands)

Breugel, van M.

2007-01-01

The succession of tropical secondary forests on abandoned agricultural fields has been studied since long, most often by comparing stands of different age since abandonment. These so-called chronosequence studies have yielded much insight in general patterns of succession and the constraints and

When a tree falls: Controls on wood decay predict standing dead tree fall and new risks in changing forests.

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Oberle, Brad; Ogle, Kiona; Zanne, Amy E; Woodall, Christopher W

2018-01-01

When standing dead trees (snags) fall, they have major impacts on forest ecosystems. Snag fall can redistribute wildlife habitat and impact public safety, while governing important carbon (C) cycle consequences of tree mortality because ground contact accelerates C emissions during deadwood decay. Managing the consequences of altered snag dynamics in changing forests requires predicting when snags fall as wood decay erodes mechanical resistance to breaking forces. Previous studies have pointed to common predictors, such as stem size, degree of decay and species identity, but few have assessed the relative strength of underlying mechanisms driving snag fall across biomes. Here, we analyze nearly 100,000 repeated snag observations from boreal to subtropical forests across the eastern United States to show that wood decay controls snag fall in ways that could generate previously unrecognized forest-climate feedback. Warmer locations where wood decays quickly had much faster rates of snag fall. The effect of temperature on snag fall was so strong that in a simple forest C model, anticipated warming by mid-century reduced snag C by 22%. Furthermore, species-level differences in wood decay resistance (durability) accurately predicted the timing of snag fall. Differences in half-life for standing dead trees were similar to expected differences in the service lifetimes of wooden structures built from their timber. Strong effects of temperature and wood durability imply future forests where dying trees fall and decay faster than at present, reducing terrestrial C storage and snag-dependent wildlife habitat. These results can improve the representation of forest C cycling and assist forest managers by helping predict when a dead tree may fall.

Effects of dwarf mistletoe on stand structure of lodgepole pine forests 21-28 years post-mountain pine beetle epidemic in central Oregon.

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Michelle C Agne

Full Text Available Lodgepole pine (Pinus contorta forests are widely distributed throughout North America and are subject to mountain pine beetle (Dendroctonus ponderosae epidemics, which have caused mortality over millions of hectares of mature trees in recent decades. Mountain pine beetle is known to influence stand structure, and has the ability to impact many forest processes. Dwarf mistletoe (Arceuthobium americanum also influences stand structure and occurs frequently in post-mountain pine beetle epidemic lodgepole pine forests. Few studies have incorporated both disturbances simultaneously although they co-occur frequently on the landscape. The aim of this study is to investigate the stand structure of lodgepole pine forests 21-28 years after a mountain pine beetle epidemic with varying levels of dwarf mistletoe infection in the Deschutes National Forest in central Oregon. We compared stand density, stand basal area, canopy volume, proportion of the stand in dominant/codominant, intermediate, and suppressed cohorts, average height and average diameter of each cohort, across the range of dwarf mistletoe ratings to address differences in stand structure. We found strong evidence of a decrease in canopy volume, suppressed cohort height, and dominant/codominant cohort diameter with increasing stand-level dwarf mistletoe rating. There was strong evidence that as dwarf mistletoe rating increases, proportion of the stand in the dominant/codominant cohort decreases while proportion of the stand in the suppressed cohort increases. Structural differences associated with variable dwarf mistletoe severity create heterogeneity in this forest type and may have a significant influence on stand productivity and the resistance and resilience of these stands to future biotic and abiotic disturbances. Our findings show that it is imperative to incorporate dwarf mistletoe when studying stand productivity and ecosystem recovery processes in lodgepole pine forests because of its

Effects of dwarf mistletoe on stand structure of lodgepole pine forests 21-28 years post-mountain pine beetle epidemic in central Oregon.

Science.gov (United States)

Agne, Michelle C; Shaw, David C; Woolley, Travis J; Queijeiro-Bolaños, Mónica E

2014-01-01

Lodgepole pine (Pinus contorta) forests are widely distributed throughout North America and are subject to mountain pine beetle (Dendroctonus ponderosae) epidemics, which have caused mortality over millions of hectares of mature trees in recent decades. Mountain pine beetle is known to influence stand structure, and has the ability to impact many forest processes. Dwarf mistletoe (Arceuthobium americanum) also influences stand structure and occurs frequently in post-mountain pine beetle epidemic lodgepole pine forests. Few studies have incorporated both disturbances simultaneously although they co-occur frequently on the landscape. The aim of this study is to investigate the stand structure of lodgepole pine forests 21-28 years after a mountain pine beetle epidemic with varying levels of dwarf mistletoe infection in the Deschutes National Forest in central Oregon. We compared stand density, stand basal area, canopy volume, proportion of the stand in dominant/codominant, intermediate, and suppressed cohorts, average height and average diameter of each cohort, across the range of dwarf mistletoe ratings to address differences in stand structure. We found strong evidence of a decrease in canopy volume, suppressed cohort height, and dominant/codominant cohort diameter with increasing stand-level dwarf mistletoe rating. There was strong evidence that as dwarf mistletoe rating increases, proportion of the stand in the dominant/codominant cohort decreases while proportion of the stand in the suppressed cohort increases. Structural differences associated with variable dwarf mistletoe severity create heterogeneity in this forest type and may have a significant influence on stand productivity and the resistance and resilience of these stands to future biotic and abiotic disturbances. Our findings show that it is imperative to incorporate dwarf mistletoe when studying stand productivity and ecosystem recovery processes in lodgepole pine forests because of its potential to

Evaluation of three classifiers in mapping forest stand types using ...

African Journals Online (AJOL)

EJIRO

applied for classification of the image. Supervised classification technique using maximum likelihood algorithm is the most commonly and widely used method for land cover classification (Jia and Richards, 2006). In Australia, the maximum likelihood classifier was effectively used to map different forest stand types with high.

Interactions of changing climate and shifts in forest composition on stand carbon balance

Science.gov (United States)

Chiang Jyh-Min; Louis Iverson; Anantha Prasad; Kim Brown

2006-01-01

Given that climate influences forest biogeographic distribution, many researchers have created models predicting shifts in tree species range with future climate change scenarios. The objective of this study is to investigate the forest carbon consequences of shifts in stand species composition with current and future climate scenarios using such a model.

Variability of sun-induced chlorophyll fluorescence according to stand age-related processes in a managed loblolly pine forest.

Science.gov (United States)

Colombo, Roberto; Celesti, Marco; Bianchi, Remo; Campbell, Petya K E; Cogliati, Sergio; Cook, Bruce D; Corp, Lawrence A; Damm, Alexander; Domec, Jean-Christophe; Guanter, Luis; Julitta, Tommaso; Middleton, Elizabeth M; Noormets, Asko; Panigada, Cinzia; Pinto, Francisco; Rascher, Uwe; Rossini, Micol; Schickling, Anke

2018-02-20

Leaf fluorescence can be used to track plant development and stress, and is considered the most direct measurement of photosynthetic activity available from remote sensing techniques. Red and far-red sun-induced chlorophyll fluorescence (SIF) maps were generated from high spatial resolution images collected with the HyPlant airborne spectrometer over even-aged loblolly pine plantations in North Carolina (United States). Canopy fluorescence yield (i.e., the fluorescence flux normalized by the light absorbed) in the red and far-red peaks was computed. This quantifies the fluorescence emission efficiencies that are more directly linked to canopy function compared to SIF radiances. Fluorescence fluxes and yields were investigated in relation to tree age to infer new insights on the potential of those measurements in better describing ecosystem processes. The results showed that red fluorescence yield varies with stand age. Young stands exhibited a nearly twofold higher red fluorescence yield than mature forest plantations, while the far-red fluorescence yield remained constant. We interpreted this finding in a context of photosynthetic stomatal limitation in aging loblolly pine stands. Current and future satellite missions provide global datasets of SIF at coarse spatial resolution, resulting in intrapixel mixture effects, which could be a confounding factor for fluorescence signal interpretation. To mitigate this effect, we propose a surrogate of the fluorescence yield, namely the Canopy Cover Fluorescence Index (CCFI) that accounts for the spatial variability in canopy structure by exploiting the vegetation fractional cover. It was found that spatial aggregation tended to mask the effective relationships, while the CCFI was still able to maintain this link. This study is a first attempt in interpreting the fluorescence variability in aging forest stands and it may open new perspectives in understanding long-term forest dynamics in response to future climatic

Post-cultural stand dynamics in an abandoned chestnut coppice at its ecological border

Directory of Open Access Journals (Sweden)

2006-01-01

Full Text Available Until the be­ginning of the last century, chestnut has played an important role as staple food and primary wood source. In many cases it was cultivated at the border of its ecological limits where it was planted by man in place of the original and more site-adapted tree species. However, with the abandonment of the rural activities, ma­nagement of chestnut forests was progressively left starting from more marginal areas, usually occupied by coppice stands. After the interruption of the traditional coppice management system (usual rotation periods of 10-25 years, natural intra- and interspecific competition dynamics have become the driving force of the stand evolution. This may lead to dramatic changes in both structure and species composition of the stands. The aim of this study is to analyse the post-cultural evolution of an abandoned chestnut coppice in the Pesio Valley (Piedmont, Italy in order to highlight the competition among different "basic silvi­cultural components" of the forest using a dendroecological approach. The "basic silvicultural components" are intended as the elements defined as groups of trees of the stand that have similar features such as silvi­culturally relevant attributes: species (chestnut, beech, fir, origin (seed, sprout and cultural age and function (standard/reserve, maiden, shoot, regeneration, dead tree. The mean growth curves of the compo­nents show the different fitness of each category. From a general point of view, the beech and fir components show a better competitive potential in comparison with chestnut. Among chestnut components, maidens from seeds reveal a better growth trend compared to coppice shoots and standards.

Measuring and Modeling the Effects of Alternate Post-Fire Successional Trajectories on Boreal Forest Carbon Dynamics

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Loranty, M. M.; Goetz, S. J.; Mack, M. C.; Alexander, H. D.; Beck, P. S.

2011-12-01

High latitude ecosystems are experiencing amplified climate warming, and recent evidence suggests concurrent intensification of fire disturbance regimes. In central Alaskan boreal forests, severe burns consume more of the soil organic layer, resulting in increased establishment of deciduous seedlings and altered post-fire stand composition with increased deciduous dominance. Quantifying differences in ecosystem carbon (C) dynamics between forest successional trajectories in response to burn severity is essential for understanding potential changes in regional or global feedbacks between boreal forests and climate. We used the Biome BioGeochemical Cycling model (Biome-BGC) to quantify differences in C stocks and fluxes associated with alternate post-fire successional trajectories related to fire severity. A version of Biome-BGC that allows alternate competing vegetation types was calibrated against a series of aboveground biomass observations from chronosequences of stands with differing post-fire successional trajectories characterized by the proportion of deciduous biomass. The model was able to reproduce observed patterns of biomass accumulation after fire, with stands dominated by deciduous species sequestering more C at a faster rate than stands dominated by conifers. Modeled C fluxes suggest that stands dominated by deciduous species are a stronger sink of atmospheric C soon after disturbance than coniferous stands. These results agree with the few available C flux observations. We use a historic database in conjunction with a map of deciduous canopy cover to explore the consequences of ongoing and potential future changes in the fire regime on central Alaskan C balance.

How fast will trees die? A transition matrix model of ash decline in forest stands infested by emerald ash borer

Science.gov (United States)

Kathleen S. Knight; Robert P. Long; Joanne Rebbeck; Annemarie Smith; Kamal Gandhi; Daniel A. Herms

2008-01-01

We recorded Fraxinus spp. tree health and other forest stand characteristics for 68 plots in 21 EAB-infested forest stands in Michigan and Ohio in 2005 and 2007. Fraxinus spp. were a dominant component of these stands, with more than 900 ash trees (including Fraxinus americana, Fraxinus pennsylvanica, Fraxinus profunda...

Stand-level variation in evapotranspiration in non-water-limited eucalypt forests

Science.gov (United States)

Benyon, Richard G.; Nolan, Rachael H.; Hawthorn, Sandra N. D.; Lane, Patrick N. J.

2017-08-01

To better understand water and energy cycles in forests over years to decades, measurements of spatial and long-term temporal variability in evapotranspiration (Ea) are needed. In mountainous terrain, plot-level measurements are important to achieving this. Forest inventory data including tree density and size measurements, often collected repeatedly over decades, sample the variability occurring within the geographic and topographic range of specific forest types. Using simple allometric relationships, tree stocking and size data can be used to estimate variables including sapwood area index (SAI), which may be strongly correlated with annual Ea. This study analysed plot-level variability in SAI and its relationship with overstorey and understorey transpiration, interception and evaporation over a 670 m elevation gradient, in non-water-limited, even-aged stands of Eucalyptus regnans F. Muell. to determine how well spatial variation in annual Ea from forests can be mapped using SAI. Over the 3 year study, mean sap velocity in five E. regnans stands was uncorrelated with overstorey sapwood area index (SAI) or elevation: annual transpiration was predicted well by SAI (R2 0.98). Overstorey and total annual interception were positively correlated with SAI (R2 0.90 and 0.75). Ea from the understorey was strongly correlated with vapour pressure deficit (VPD) and net radiation (Rn) measured just above the understorey, but relationships between understorey Ea and VPD and Rn differed between understorey types and understorey annual Ea was not correlated with SAI. Annual total Ea was also strongly correlated with SAI: the relationship being similar to two previous studies in the same region, despite differences in stand age and species. Thus, spatial variation in annual Ea can be reliably mapped using measurements of SAI.

Climatic control of stand thinning in unmanaged spruce forests of the southern taiga in European Russia

International Nuclear Information System (INIS)

Vygodskaya, N.N.; Schulze, E.D.; Tchebakova, N.M.

2002-01-01

The demography of Picea abies trees was studied over a period of about 30 yr on permanent plots in six forest types of an unmanaged forest located in a forest reserve of the Southern Taiga, NW of Moscow. This study encompassed a broad range of conditions that are typical for old growth spruce forests in the boreal region, including sites with a high water table and well drained sites, podzolic soils, acidic soils and organic soils. At all sites stand density, tree height, breast height diameter and age has been periodically recorded since 1968. Tree density ranged between 178 and 1035 trees/ha for spruce and between 232 and 1168 trees/ha for the whole stand, including mainly Betula and Populus. Biomass ranged between 5.4 and 170 tdw/ha for spruce and between 33 to 198 tdw/ha for the whole stand. Averaged over a long period of time, biomass did not change with stand density according to the self-thinning rule. In fact, on most sites biomass remained almost constant in the long term, while stand density decreased. The study demonstrates that the loss of living trees was not regulated by competitive interactions between trees, but by disturbances caused by climatic events. Dry years caused losses of minor and younger trees without affecting biomass. In contrast, periodic storms resulted in a loss of biomass without affecting density, except for extreme events, where the whole stand may fall. Dry years followed by wet years enhance the effect on stand density. Since mainly younger trees were lost, the apparent average age of the stand increased more than real time (20% for Picea). Average mortality was 2.8 ± 0.5% yr 1 for spruce. Thus, the forest is turned over once every 160-180 yr by disturbances. The demography of dead trees shows that the rate of decay depends on the way the tree died. Storm causes uprooting and stem breakage, where living trees fall to the forest floor and decay with a mean residence time (t1/2) of about 16 yr (decomposition rate constant k d = 0

The nature of the beast: examining climate adaptation options in forests with stand-replacing fire regimes

Science.gov (United States)

Joshua S. Halofsky; Daniel C. Donato; Jerry F. Franklin; Jessica E. Halofsky; David L. Peterson; Brian J. Harvey

2018-01-01

Building resilience to natural disturbances is a key to managing forests for adaptation to climate change. To date, most climate adaptation guidance has focused on recommendations for frequent-fire forests, leaving few published guidelines for forests that naturally experience infrequent, stand-replacing wildfires. Because most such forests are inherently resilient to...

The Oldest, Slowest Rainforests in the World? Massive Biomass and Slow Carbon Dynamics of Fitzroya cupressoides Temperate Forests in Southern Chile.

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Rocio Urrutia-Jalabert

Full Text Available Old-growth temperate rainforests are, per unit area, the largest and most long-lived stores of carbon in the terrestrial biosphere, but their carbon dynamics have rarely been described. The endangered Fitzroya cupressoides forests of southern South America include stands that are probably the oldest dense forest stands in the world, with long-lived trees and high standing biomass. We assess and compare aboveground biomass, and provide the first estimates of net primary productivity (NPP, carbon allocation and mean wood residence time in medium-age stands in the Alerce Costero National Park (AC in the Coastal Range and in old-growth forests in the Alerce Andino National Park (AA in the Andean Cordillera. Aboveground live biomass was 113-114 Mg C ha(-1 and 448-517 Mg C ha(-1 in AC and AA, respectively. Aboveground productivity was 3.35-3.36 Mg C ha(-1 year(-1 in AC and 2.22-2.54 Mg C ha(-1 year(-1 in AA, values generally lower than others reported for temperate wet forests worldwide, mainly due to the low woody growth of Fitzroya. NPP was 4.21-4.24 and 3.78-4.10 Mg C ha(-1 year(-1 in AC and AA, respectively. Estimated mean wood residence time was a minimum of 539-640 years for the whole forest in the Andes and 1368-1393 years for only Fitzroya in this site. Our biomass estimates for the Andes place these ecosystems among the most massive forests in the world. Differences in biomass production between sites seem mostly apparent as differences in allocation rather than productivity. Residence time estimates for Fitzroya are the highest reported for any species and carbon dynamics in these forests are the slowest reported for wet forests worldwide. Although primary productivity is low in Fitzroya forests, they probably act as ongoing biomass carbon sinks on long-term timescales due to their low mortality rates and exceptionally long residence times that allow biomass to be accumulated for millennia.

The Oldest, Slowest Rainforests in the World? Massive Biomass and Slow Carbon Dynamics of Fitzroya cupressoides Temperate Forests in Southern Chile.

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Urrutia-Jalabert, Rocio; Malhi, Yadvinder; Lara, Antonio

2015-01-01

Old-growth temperate rainforests are, per unit area, the largest and most long-lived stores of carbon in the terrestrial biosphere, but their carbon dynamics have rarely been described. The endangered Fitzroya cupressoides forests of southern South America include stands that are probably the oldest dense forest stands in the world, with long-lived trees and high standing biomass. We assess and compare aboveground biomass, and provide the first estimates of net primary productivity (NPP), carbon allocation and mean wood residence time in medium-age stands in the Alerce Costero National Park (AC) in the Coastal Range and in old-growth forests in the Alerce Andino National Park (AA) in the Andean Cordillera. Aboveground live biomass was 113-114 Mg C ha(-1) and 448-517 Mg C ha(-1) in AC and AA, respectively. Aboveground productivity was 3.35-3.36 Mg C ha(-1) year(-1) in AC and 2.22-2.54 Mg C ha(-1) year(-1) in AA, values generally lower than others reported for temperate wet forests worldwide, mainly due to the low woody growth of Fitzroya. NPP was 4.21-4.24 and 3.78-4.10 Mg C ha(-1) year(-1) in AC and AA, respectively. Estimated mean wood residence time was a minimum of 539-640 years for the whole forest in the Andes and 1368-1393 years for only Fitzroya in this site. Our biomass estimates for the Andes place these ecosystems among the most massive forests in the world. Differences in biomass production between sites seem mostly apparent as differences in allocation rather than productivity. Residence time estimates for Fitzroya are the highest reported for any species and carbon dynamics in these forests are the slowest reported for wet forests worldwide. Although primary productivity is low in Fitzroya forests, they probably act as ongoing biomass carbon sinks on long-term timescales due to their low mortality rates and exceptionally long residence times that allow biomass to be accumulated for millennia.

Carbon dynamics of mature and regrowth tropical forests derived from a pantropical database (TropForC-db).

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Anderson-Teixeira, Kristina J; Wang, Maria M H; McGarvey, Jennifer C; LeBauer, David S

2016-05-01

Tropical forests play a critical role in the global carbon (C) cycle, storing ~45% of terrestrial C and constituting the largest component of the terrestrial C sink. Despite their central importance to the global C cycle, their ecosystem-level C cycles are not as well-characterized as those of extra-tropical forests, and knowledge gaps hamper efforts to quantify C budgets across the tropics and to model tropical forest-climate interactions. To advance understanding of C dynamics of pantropical forests, we compiled a new database, the Tropical Forest C database (TropForC-db), which contains data on ground-based measurements of ecosystem-level C stocks and annual fluxes along with disturbance history. This database currently contains 3568 records from 845 plots in 178 geographically distinct areas, making it the largest and most comprehensive database of its type. Using TropForC-db, we characterized C stocks and fluxes for young, intermediate-aged, and mature forests. Relative to existing C budgets of extra-tropical forests, mature tropical broadleaf evergreen forests had substantially higher gross primary productivity (GPP) and ecosystem respiration (Reco), their autotropic respiration (Ra) consumed a larger proportion (~67%) of GPP, and their woody stem growth (ANPPstem) represented a smaller proportion of net primary productivity (NPP, ~32%) or GPP (~9%). In regrowth stands, aboveground biomass increased rapidly during the first 20 years following stand-clearing disturbance, with slower accumulation following agriculture and in deciduous forests, and continued to accumulate at a slower pace in forests aged 20-100 years. Most other C stocks likewise increased with stand age, while potential to describe age trends in C fluxes was generally data-limited. We expect that TropForC-db will prove useful for model evaluation and for quantifying the contribution of forests to the global C cycle. The database version associated with this publication is archived in Dryad (DOI

Diameter distribution in a Brazilian tropical dry forest domain: predictions for the stand and species.

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Lima, Robson B DE; Bufalino, Lina; Alves, Francisco T; Silva, José A A DA; Ferreira, Rinaldo L C

2017-01-01

Currently, there is a lack of studies on the correct utilization of continuous distributions for dry tropical forests. Therefore, this work aims to investigate the diameter structure of a brazilian tropical dry forest and to select suitable continuous distributions by means of statistic tools for the stand and the main species. Two subsets were randomly selected from 40 plots. Diameter at base height was obtained. The following functions were tested: log-normal; gamma; Weibull 2P and Burr. The best fits were selected by Akaike's information validation criterion. Overall, the diameter distribution of the dry tropical forest was better described by negative exponential curves and positive skewness. The forest studied showed diameter distributions with decreasing probability for larger trees. This behavior was observed for both the main species and the stand. The generalization of the function fitted for the main species show that the development of individual models is needed. The Burr function showed good flexibility to describe the diameter structure of the stand and the behavior of Mimosa ophthalmocentra and Bauhinia cheilantha species. For Poincianella bracteosa, Aspidosperma pyrifolium and Myracrodum urundeuva better fitting was obtained with the log-normal function.

Dynamics of Plains Cottonwood ( Populus deltoides) Forests and Historical Landscape Change along Unchannelized Segments of the Missouri River, USA

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Dixon, Mark D.; Johnson, W. Carter; Scott, Michael L.; Bowen, Daniel E.; Rabbe, Lisa A.

2012-05-01

Construction of six large dams and reservoirs on the Missouri River over the last 50-75 years has resulted in major landscape changes and alterations in flow patterns, with implications for riparian forests dominated by plains cottonwood ( Populus deltoides). We quantified changes in land cover from 1892-1950s and the 1950s-2006 and the current extent and age structure of cottonwood forests on seven segments (two reservoir and five remnant floodplain) comprising 1127 km (53 %) of the unchannelized upper two-thirds of the Missouri River. Riparian forest area declined by 49 %; grassland 61 %; shrubland 52 %; and sandbar habitat 96 %; while agricultural cropland increased six-fold and river/reservoir surface area doubled from 1892 to 2006. Net rates of erosion and accretion declined between the 1892-1950s and 1950s-2006 periods. Accretion exceeded erosion on remnant floodplain segments, resulting in declines in active channel width, particularly in 1950s-2006. Across all study segments in 2006, most cottonwood stands (67 %) were >50 years old, 22 % were 25-50 years old, and only 10 % were <25 years old. Among stands <50 years old, the higher proportion of 25-50 year old stands represents recruitment that accompanied initial post-dam channel narrowing; while declines in sandbar and shrubland area and the low proportion of stands <25 years old suggest declines in geomorphic dynamism and limited recruitment under recent river management. Future conservation and restoration efforts should focus both on limiting further loss of remnant cottonwood stands and developing approaches to restore river dynamics and cottonwood recruitment processes.

Landscape perception based on personal attributes in determining the scenic beauty of in-stand natural secondary forests

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Yong Chen

2016-06-01

Full Text Available The aim of this paper was to validate factors affecting the in-stand landscape quality and how important each factor was in determining scenic beauty of natural secondary forests. The study was limited to 23 stand-level cases of natural secondary forests in Shen Zhen city in southern China. Typical samples of photographs and public estimations were applied to evaluate scenic beauty inside the natural secondary forests. The major factors were then selected by multiple linear-regression analysis and a model between scenic beauty estimation (SBE values and in-stand landscape features was established. Rise in crown density, fall in plant litter, glow in color of trunk, fall in arbor richness, and rise in visible distance increased scenic beauty values of in-stand landscape. These five factors significantly explained the differences in scenic beauty, and together accounted for 45% of total variance in SBEs. Personal factors (e.g. gender, age and education did not significantly affect the ratings of landscape photos, although variations of landscape quality were affected by some personal factors. Results of this study will assist policymakers, silviculturists and planners in landscape design and management of natural secondary forests in Shenzhen city. People can improve the scenic beauty values by pruning branches and clearing plant litter, which subsequently improve the forest health and contribute to forest recreation.

Energy balance and evaporation of a short-rotation willow forest. Variation with season and stand development

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Iritz, Z.

1996-10-01

Energy balance and evaporation of a short-rotation willow (Salix viminalis L.) forest was studied in relation to season and stand development. The developmental stage of the forest stand considerably influenced how the energy, received as net radiation, was partitioned between the connective fluxes and the storage components. The main part of the available energy was utilised for evaporation during most of the season. Only at the beginning of the season did the willow forest supply heat to the atmosphere. Later in the season, energy was taken from air and utilised for evaporation, which resulted in negative sensible heat fluxes. Soil heat storage was also a significant term in the energy balance and also strongly depended on canopy development. Changes in energy partitioning relative to leaf area indices indicated the existence of a threshold value for leaf area index of the developing canopy. The analysis suggested that the canopy of the willow forest could be considered as closed at a leaf area index of 2. It was further found that evaporation from well-irrigated willow forest occurred also during night-time, particularly in windy and dry weather conditions. The sources of nocturnal evaporation were both the canopy, i.e. indicating non-closed stomata, and the soil surface. Partitioning of the total evaporation into components was investigated using a physically-based model with a two-layer aboveground representation and a two-layer soil module. The model estimates evaporation with respect to developmental stage of the willow stand and also takes into account the interaction between the fluxes from the canopy and the soil surface. Good performance of the model indicated that, after further testing in drier conditions, it could be used as a tool for analysing the prerequisites for energy-forest establishment, and practical management of energy forest stands. 37 refs, 9 figs

Forest structure, stand composition, and climate-growth response in montane forests of Jiuzhaigou National Nature Reserve, China.

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Mark W Schwartz

Full Text Available Montane forests of western China provide an opportunity to establish baseline studies for climate change. The region is being impacted by climate change, air pollution, and significant human impacts from tourism. We analyzed forest stand structure and climate-growth relationships from Jiuzhaigou National Nature Reserve in northwestern Sichuan province, along the eastern edge of the Tibetan plateau. We conducted a survey to characterize forest stand diversity and structure in plots occurring between 2050 and 3350 m in elevation. We also evaluated seedling and sapling recruitment and tree-ring data from four conifer species to assess: 1 whether the forest appears in transition toward increased hardwood composition; 2 if conifers appear stressed by recent climate change relative to hardwoods; and 3 how growth of four dominant species responds to recent climate. Our study is complicated by clear evidence of 20(th century timber extraction. Focusing on regions lacking evidence of logging, we found a diverse suite of conifers (Pinus, Abies, Juniperus, Picea, and Larix strongly dominate the forest overstory. We found population size structures for most conifer tree species to be consistent with self-replacement and not providing evidence of shifting composition toward hardwoods. Climate-growth analyses indicate increased growth with cool temperatures in summer and fall. Warmer temperatures during the growing season could negatively impact conifer growth, indicating possible seasonal climate water deficit as a constraint on growth. In contrast, however, we found little relationship to seasonal precipitation. Projected warming does not yet have a discernible signal on trends in tree growth rates, but slower growth with warmer growing season climates suggests reduced potential future forest growth.

Methods for registration laser scanner point clouds in forest stands

International Nuclear Information System (INIS)

Bienert, A.; Pech, K.; Maas, H.-G.

2011-01-01

Laser scanning is a fast and efficient 3-D measurement technique to capture surface points describing the geometry of a complex object in an accurate and reliable way. Besides airborne laser scanning, terrestrial laser scanning finds growing interest for forestry applications. These two different recording platforms show large differences in resolution, recording area and scan viewing direction. Using both datasets for a combined point cloud analysis may yield advantages because of their largely complementary information. In this paper, methods will be presented to automatically register airborne and terrestrial laser scanner point clouds of a forest stand. In a first step, tree detection is performed in both datasets in an automatic manner. In a second step, corresponding tree positions are determined using RANSAC. Finally, the geometric transformation is performed, divided in a coarse and fine registration. After a coarse registration, the fine registration is done in an iterative manner (ICP) using the point clouds itself. The methods are tested and validated with a dataset of a forest stand. The presented registration results provide accuracies which fulfill the forestry requirements [de

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

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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.

Fine root dynamics in lodgepole pine and white spruce stands along productivity gradients in reclaimed oil sands sites.

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Jamro, Ghulam Murtaza; Chang, Scott X; Naeth, M Anne; Duan, Min; House, Jason

2015-10-01

Open-pit mining activities in the oil sands region of Alberta, Canada, create disturbed lands that, by law, must be reclaimed to a land capability equivalent to that existed before the disturbance. Re-establishment of forest cover will be affected by the production and turnover rate of fine roots. However, the relationship between fine root dynamics and tree growth has not been studied in reclaimed oil sands sites. Fine root properties (root length density, mean surface area, total root biomass, and rates of root production, turnover, and decomposition) were assessed from May to October 2011 and 2012 using sequential coring and ingrowth core methods in lodgepole pine (Pinus contorta Dougl.) and white spruce (Picea glauca (Moench.) Voss) stands. The pine and spruce stands were planted on peat mineral soil mix placed over tailings sand and overburden substrates, respectively, in reclaimed oil sands sites in Alberta. We selected stands that form a productivity gradient (low, medium, and high productivities) of each tree species based on differences in tree height and diameter at breast height (DBH) increments. In lodgepole pine stands, fine root length density and fine root production, and turnover rates were in the order of high > medium > low productivity sites and were positively correlated with tree height and DBH and negatively correlated with soil salinity (P < 0.05). In white spruce stands, fine root surface area was the only parameter that increased along the productivity gradient and was negatively correlated with soil compaction. In conclusion, fine root dynamics along the stand productivity gradients were closely linked to stand productivity and were affected by limiting soil properties related to the specific substrate used for reconstructing the reclaimed soil. Understanding the impact of soil properties on fine root dynamics and overall stand productivity will help improve land reclamation outcomes.

Effect of forest structural change on carbon storage in a coastal Metasequoia glyptostroboides stand.

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Cheng, Xiangrong; Yu, Mukui; Wu, Tonggui

2013-01-01

Forest structural change affects the forest's growth and the carbon storage. Two treatments, thinning (30% thinning intensity) and underplanting plus thinning, are being implemented in a coastal Metasequoia glyptostroboides forest shelterbelt in Eastern China. The vegetation carbon storage significantly increased in the underplanted and thinned treatments compared with that in the unthinned treatment (P 0.05). The soil light fraction organic carbon (LFOC) was significantly higher at the 0-15 cm soil layer in the thinned and underplanted stands compared with that in the unthinned stand (P < 0.05). The soil respiration of the underplanted treatment was significantly higher than that of the unthinned treatment only in July (P < 0.05). This study concludes that 30% thinning and underplanting after thinning could be more favorable to carbon sequestration for M. glyptostroboides plantations in the coastal areas of Eastern China.

Tree Diversity Enhances Stand Carbon Storage but Not Leaf Area in a Subtropical Forest.

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Castro-Izaguirre, Nadia; Chi, Xiulian; Baruffol, Martin; Tang, Zhiyao; Ma, Keping; Schmid, Bernhard; Niklaus, Pascal A

2016-01-01

Research about biodiversity-productivity relationships has focused on herbaceous ecosystems, with results from tree field studies only recently beginning to emerge. Also, the latter are concentrated largely in the temperate zone. Tree species diversity generally is much higher in subtropical and tropical than in temperate or boreal forests, with reasons not fully understood. Niche overlap and thus complementarity in the use of resources that support productivity may be lower in forests than in herbaceous ecosystems, suggesting weaker productivity responses to diversity change in forests. We studied stand basal area, vertical structure, leaf area, and their relationship with tree species richness in a subtropical forest in south-east China. Permanent forest plots of 30 x 30 m were selected to span largely independent gradients in tree species richness and secondary successional age. Plots with higher tree species richness had a higher stand basal area. Also, stand basal area increases over a 4-year census interval were larger at high than at low diversity. These effects translated into increased carbon stocks in aboveground phytomass (estimated using allometric equations). A higher variability in tree height in more diverse plots suggested that these effects were facilitated by denser canopy packing due to architectural complementarity between species. In contrast, leaf area was not or even negatively affected by tree diversity, indicating a decoupling of carbon accumulation from leaf area. Alternatively, the same community leaf area might have assimilated more C per time interval in more than in less diverse plots because of differences in leaf turnover and productivity or because of differences in the display of leaves in vertical and horizontal space. Overall, our study suggests that in species-rich forests niche-based processes support a positive diversity-productivity relationship and that this translates into increased carbon storage in long-lived woody

Effects of climate, CO2 concentration, nitrogen deposition, and stand age changes on the carbon budget of China's forests

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Zhang, C.; Ju, W.; Zhang, F.; Mao, D.; Wang, X.

2017-12-01

Forests play an irreplaceable role in the Earth's terrestrial carbon budget which retard the atmospheric CO2 buildup. Understanding the factors controlling forest carbon budget is critical for reducing uncertainties in projections of future climate. The relative importance of climate, atmospheric CO2 concentration, nitrogen deposition, and stand age changes on carbon budget, however, remains unclear for China's forests. In this study, we quantify individual contribution of these drivers to the trends of forest carbon budget in China from 1901 to 2012 by integrating national datasets, the updated Integrated Terrestrial Ecosystem Carbon Cycle (InTEC) model and factorial simulations. Results showed that the average carbon sink in China's forests from 1982 to 2012 was 186.9 Tg C yr-1 with 68% (127.6 Tg C yr-1) of the sink in living biomass because of the integrated effects of climate, atmospheric CO2 concentration, nitrogen deposition, and stand age factors. Compared with the simulation of all factors combined, the estimated carbon sink during 1901-2012 would be reduced by 41.8 Tg C yr-1 if climate change, atmospheric CO2 concentration and nitrogen deposition factors were omitted, and reduced by 25.0 Tg C yr-1 if stand age factor was omitted. In most decades, these factors increased forest carbon sinks with the largest of 101.3, 62.9, and 44.0 Tg C yr-1 from 2000 to 2012 contributed by stand age, CO2 concentration and nitrogen deposition, respectively. During 1901-2012, climate change, CO2 concentration, nitrogen deposition and stand age contributed -13.3, 21.4, 15.4 and 25.0 Tg C yr-1 to the averaged carbon sink of China's forests, respectively. Our study also showed diverse regional patterns of forest carbon budget related to the importance of driving factors. Stand age effect was the largest in most regions, but the effects of CO2 concentration and nitrogen deposition were dominant in southern China.

Quantifying Components of Soil Respiration and Their Response to Abiotic Factors in Two Typical Subtropical Forest Stands, Southwest China

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Yu, Lei; Wang, Yujie; Wang, Yunqi; Sun, Suqi; Liu, Liziyuan

2015-01-01

Separating the components of soil respiration and understanding the roles of abiotic factors at a temporal scale among different forest types are critical issues in forest ecosystem carbon cycling. This study quantified the proportions of autotrophic (R A) and heterotrophic (R H) in total soil (R T) respiration using trenching and litter removal. Field studies were conducted in two typical subtropical forest stands (broadleaf and needle leaf mixed forest; bamboo forest) at Jinyun Mountain, near the Three Georges Reservoir in southwest China, during the growing season (Apr.–Sep.) from 2010 to 2012. The effects of air temperature (AT), soil temperature (ST) and soil moisture (SM) at 6cm depth, solar radiation (SR), pH on components of soil respiration were analyzed. Results show that: 1) SR, AT, and ST exhibited a similar temporal trend. The observed abiotic factors showed slight interannual variability for the two forest stands. 2) The contributions of R H and R A to R T for broadleaf and needle leaf mixed forest were 73.25% and 26.75%, respectively, while those for bamboo forest were 89.02% and 10.98%, respectively; soil respiration peaked from June to July. In both stands, CO2 released from the decomposition of soil organic matter (SOM), the strongest contributor to R T, accounted for over 63% of R H. 3) AT and ST were significantly positively correlated with R T and its components (psoil respiration. 4) Components of soil respiration were significantly different between two forest stands (psoil respiration and its components. PMID:25680112

Multi-Cohort Stand Structural Classification: Ground- and LiDAR-based Approaches for Boreal Mixedwood and Black Spruce Forest Types of Northeastern Ontario

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Kuttner, Benjamin George

Natural fire return intervals are relatively long in eastern Canadian boreal forests and often allow for the development of stands with multiple, successive cohorts of trees. Multi-cohort forest management (MCM) provides a strategy to maintain such multi-cohort stands that focuses on three broad phases of increasingly complex, post-fire stand development, termed "cohorts", and recommends different silvicultural approaches be applied to emulate different cohort types. Previous research on structural cohort typing has relied upon primarily subjective classification methods; in this thesis, I develop more comprehensive and objective methods for three common boreal mixedwood and black spruce forest types in northeastern Ontario. Additionally, I examine relationships between cohort types and stand age, productivity, and disturbance history and the utility of airborne LiDAR to retrieve ground-based classifications and to extend structural cohort typing from plot- to stand-levels. In both mixedwood and black spruce forest types, stand age and age-related deadwood features varied systematically with cohort classes in support of an age-based interpretation of increasing cohort complexity. However, correlations of stand age with cohort classes were surprisingly weak. Differences in site productivity had a significant effect on the accrual of increasingly complex multi-cohort stand structure in both forest types, especially in black spruce stands. The effects of past harvesting in predictive models of class membership were only significant when considered in isolation of age. As an age-emulation strategy, the three cohort model appeared to be poorly suited to black spruce forests where the accrual of structural complexity appeared to be more a function of site productivity than age. Airborne LiDAR data appear to be particularly useful in recovering plot-based cohort types and extending them to the stand-level. The main gradients of structural variability detected using Li

Statistical properties of mean stand biomass estimators in a LIDAR-based double sampling forest survey design.

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H.E. Anderson; J. Breidenbach

2007-01-01

Airborne laser scanning (LIDAR) can be a valuable tool in double-sampling forest survey designs. LIDAR-derived forest structure metrics are often highly correlated with important forest inventory variables, such as mean stand biomass, and LIDAR-based synthetic regression estimators have the potential to be highly efficient compared to single-stage estimators, which...

Dynamics of soil organic matter in primary and secondary forest succession on sandy soils in The Netherlands: An application of the ROMUL model

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Nadporozhskaya, M.A.; Mohren, G.M.J.; Chertov, O.G.; Komarov, A.S.; Mikhailov, A.V.

2006-01-01

We applied the simulation model ROMUL of soil organic matter dynamics in order to analyse and predict forest soil organic matter (SOM) changes following stand growth and also to identify gaps of data and modelling problems. SOM build-up was analysed (a) from bare sand to forest soil during a primary

Contributions to the phytocoenologic study in pure european beech stand forests in Codru-Moma Mountains (North-Western Romania

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Călin-Gheorghe PĂŞCUŢ

2010-05-01

Full Text Available In the present work we present a phytocoenologic study on the associations found in pure European beech stand forests in Codru-Moma Mountains namely: Festuco drymejae-Fagetum Morariu et al. 1968, Luzulo albidae-Fagetum sylvaticae Zólyomi 1955.Characterization of the associations we studied and presentation of the tables have been made considering the selection of the most representative relevées of pure European beech forests belonging to Codru-Moma Mountains.The phytocoenoses of pure forest stands of European beech forests belonging to the two associations were analyzed in terms of floristic composition, life forms spectrum, spectrum chart of the floral elements and ecological indices.

Stand-level gas-exchange responses to seasonal drought in very young versus old Douglas-fir forests of the Pacific Northwest, USA

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Sonia Wharton; Matt Schroeder; Ken Bible; Matthias Falk; Kyaw Tha Paw U

2009-01-01

This study examines how stand age affects ecosystem mass and energy exchange response to seasonal drought in three adjacent Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests. The sites include two early seral (ES) stands (0 to 15 years old) and an old-growth (OG) (~450 to 500 years old) forest in the Wind River Experimental Forest,...

Encroachment Dynamics of Juniperus virginiana L. and Mesic Hardwood Species into Cross Timbers Forests of North-Central Oklahoma, USA

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Daniel L. Hoff

2018-02-01

Full Text Available Cross Timbers forests, typically dominated by Quercus stellata Wangenh. and Q. marilandica Muenchh., are the transition zone between eastern deciduous forest and prairie in the southern Great Plains. Fire exclusion beginning in the mid-1900s has led to increasing stand density and encroachment of fire-intolerant Juniperus virginiana L. and mesic hardwood. We measured current forest structure and tree ages of 25 stands (130 plots in north-central Oklahoma to characterize the extent and dynamics of encroachment. The respective basal area and stand density of the overstory (diameter at breast height; dbh > 10 cm were 19.0 m2 ha−1 and 407 trees ha−1 with Q. stellata comprising 43% of basal area and 42% of stand density. Quercus marilandica represented only 3% of basal area and 4% of overstory density. Juniperus virginiana represented 7% of basal area and 14% of stand density while mesic hardwoods, e.g., Celtis spp., Ulmus spp., Carya spp., 33% of basal area and stand density. The sapling layer was dominated by mesic hardwoods (68% and J. virginiana (25% while the seedling layer was dominated by mesic hardwoods (74%. The majority of Quercus recruited into the overstory between 1910–1970, while recruitment of J. virginiana and mesic hardwoods began more recently (post 1950s. Growth rate, based on the relationship between age and dbh, was faster for mesic hardwoods than for J. virginiana and Q. stellata. These results indicate that removal of recurrent surface fire as a disturbance agent has significantly altered forest composition in the Cross Timbers region by allowing encroachment of J. virginiana and fire-intolerant, mesic hardwoods. This increases wildfire risk because J. virginiana is very flammable and will alter how these forests respond to future drought and other disturbance events.

Growth and yield of all-aged Douglas-fir -- western hemlock forest stands: a matrix model with stand diversity effects.

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Jingjing Liang; Joseph Buonglorno; Robert A. Monserud

2005-01-01

A density-dependent matrix model was developed for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) -- western hemlock (Tsuga heterophylla (Raf.) Sarg.) forest stands in the Pacific Northwest of the United States. The model predicted the number and volume of trees for 4 species groups and 19 diameter classes. The parameters...

[Soil quality assessment of forest stand in different plantation esosystems].

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Huang, Yu; Wang, Silong; Feng, Zongwei; Gao, Hong; Wang, Qingkui; Hu, Yalin; Yan, Shaokui

2004-12-01

After a clear-cutting of the first generation Cunninghamia lanceolata plantation in 1982, three plantation ecosystems, pure Michelia macclurei stand (PMS), pure Chinese-fir stand (PCS) and their mixed stand, were established in spring 1983, and their effects on soil characteristics were evaluated by measuring some soil physical, chemical, microbiological and biochemical parameters. After 20 years' plantation, all test indices showed differences among different forest management models. Both PMS and MCM had a favorable effect on soil fertility maintenance. Soil quality assessment showed that some soil functions, e.g., water availability, nutrient availability, root suitability and soil quality index were all in a moderate level under the mixed and pure PMS stands, whereas in a relatively lower level under successive PCS stand. The results also showed that there existed close correlations between soil total organic C (TOC), cation exchange capacity (CEC), microbial biomass-C (Cmic) and other soil physical, chemical and biological indices. Therefore, TOC, CEC and Cmic could be used as the indicators in assessing soil quality in this study area. In addition, there were also positive correlations between soil microbial biomass-C and TOC, soil microbial biomass-N and total N, and soil microbial biomass-P and total P in the present study.

Aggregating pixel-level basal area predictions derived from LiDAR data to industrial forest stands in North-Central Idaho

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Andrew T. Hudak; Jeffrey S. Evans; Nicholas L. Crookston; Michael J. Falkowski; Brant K. Steigers; Rob Taylor; Halli Hemingway

2008-01-01

Stand exams are the principal means by which timber companies monitor and manage their forested lands. Airborne LiDAR surveys sample forest stands at much finer spatial resolution and broader spatial extent than is practical on the ground. In this paper, we developed models that leverage spatially intensive and extensive LiDAR data and a stratified random sample of...

The main forest inventory characteristics of the stands damaged by hurricane winds in the southern taiga subzone (Kostroma Oblast

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I. N. Petukhov

2016-08-01

Full Text Available In June and July 2010 in Yaroslavl, Vologda and Kostroma regions, as a result of exposure to hurricane winds, recorded several violations of extensive forest cover in the form of windfalls and windbreaks (Krylov et al., 2012; Petukhov, Nemchinova, 2014. Retrospective analysis on the basis of remote sensing data for the period 1984–2011’s was conducted. It showed, that among the 21st dedicated mass windfall within the Kostroma region and border areas, windfall July 2010 is unique in the magnitude of the total area of disturbed forest cover. According to our estimates, derived from the analysis of remote sensing (RS, its area was more than 60 thousand Ha, which is four times the average annual area of clear felling, in particular, in the Kostroma region (Petukhov, Nemchinova, 2014. In addition to determining the areas of windfall violations of forest cover, based on forest inventory data and remote sensing data analyzed taxation characteristics of forest stands affected by the impact of the seven gale-force winds within the territory of the Kostroma region. The analysis revealed the following trends in hurricane-force winds damaged trees: for parameters such as completeness, forest type and site class is observed relatively uniform stands hurricane wind damage; I.e., we have not found an association between the degree (probability of forest stands damaged data and taxation values data. An exception is the age, height, and in some cases, the predominant species plantations. Plantations dominated by spruce in the stand proved to be somewhat less, but with a predominance of pine – more resistant to hurricane winds, compared to other tree species. Selectivity is also observed for breach of stands older than 40 years and a height of over 16 meters, which is possibly related to the morphological and physiological features of the trees of a given age and height.

Multi-decade biomass dynamics in an old-growth hemlock-northern hardwood forest, Michigan, USA

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Kerry D. Woods

2014-09-01

Full Text Available Trends in living aboveground biomass and inputs to the pool of coarse woody debris (CWD in an undisturbed, old-growth hemlock-northern hardwood forest in northern MI were estimated from multi-decade observations of permanent plots. Growth and demographic data from seven plot censuses over 47 years (1962–2009, combined with one-time measurement of CWD pools, help assess biomass/carbon status of this landscape. Are trends consistent with traditional notions of late-successional forests as equilibrial ecosystems? Specifically, do biomass pools and CWD inputs show consistent long-term trends and relationships, and can living and dead biomass pools and trends be related to forest composition and history? Aboveground living biomass densities, estimated using standard allometric relationships, range from 360–450 Mg/ha among sampled stands and types; these values are among the highest recorded for northeastern North American forests. Biomass densities showed significant decade-scale variation, but no consistent trends over the full study period (one stand, originating following an 1830 fire, showed an aggrading trend during the first 25 years of the study. Even though total above-ground biomass pools are neither increasing nor decreasing, they have been increasingly dominated, over the full study period, by very large (>70 cm dbh stems and by the most shade-tolerant species (Acer saccharum and Tsuga canadensis.CWD pools measured in 2007 averaged 151 m3/ha, with highest values in Acer-dominated stands. Snag densities averaged 27/ha, but varied nearly ten-fold with canopy composition (highest in Tsuga-dominated stands, lowest in Acer-dominated; snags constituted 10–50% of CWD biomass. Annualized CWD inputs from tree mortality over the full study period averaged 1.9–3.2 Mg/ha/yr, depending on stand and species composition. CWD input rates tended to increase over the course of the study. Input rates may be expected to increase over longer

Beetle-killed stands in the South Carolina piedmont: from fuel hazards to regenerating oak forests

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Aaron D. Stottlemyer; G. Geoff Wang; Thomas A. Waldrop

2012-01-01

Impacts of spring prescribed fire, mechanical mastication, and no-treatment (control) on fuels and natural hardwood tree regeneration were examined in beetle-killed stands in the South Carolina Piedmont. Mechanical mastication ground the down and standing dead trees and live vegetation into mulch and deposited it onto the forest floor. The masticated debris layer had...

Aerodynamic resistance of spruce forest stand in relation to roughness length and airflow

Czech Academy of Sciences Publication Activity Database

Hurtalová, T.; Matějka, F.; Rožnovský, J.; Janouš, Dalibor

2003-01-01

Roč. 33, č. 3 (2003), s. 147-160 ISSN 1335-2806 R&D Projects: GA ČR(CZ) GA526/03/1104 Keywords : aerodynamic resistance * spruce forest stand * roughness length Subject RIV: DG - Athmosphere Sciences, Meteorology

Chemical composition of the humus layer, mineral soil and soil solution of 150 forest stands in the Netherlands in 1990

NARCIS (Netherlands)

Vries, de W.; Leeters, E.E.J.M.

2001-01-01

A nationwide assessment of the chemical composition of the humus layer, mineral topsoil (0-30 cm) and soil solution in both topsoil and subsoil (60-100 cm) was made for 150 forest stands in the year 1990. The stands, which were part of the national forest inventory on vitality, included seven tree

Traditional silvopastoral management and its effects on forest stand structure in northern Zagros, Iran

DEFF Research Database (Denmark)

Valipour, Ahmad; Plieninger, Tobias; Shakeri, Zahed

2014-01-01

and to investigate the effects of these practices on forest stand structure. To understand how the traditional forest management system works, empirical survey methods, in particular face to face interviews and participation in traditional practices have been employed. In general, local livelihoods depend on three......Oak forests of Iran are managed for soil conservation, water quality and other non-market ecosystem services. Nationalization policies in 1963 implied shifts from private ownership and informal traditional management to public ownership and state forest management. In spite of the nationalization......, informal practices and conventional ownership have been continued which has caused considerable conflicts between local people and the state forest administration. The aim of the study was to systematically gather the components of traditional silvopastoral management in these oak forests...

Liming with powdered oil-shale ash in a heavily damaged forest ecosystem. 2.The effect on forest condition in a pine stand

International Nuclear Information System (INIS)

Terasmaa, T.; Pikk, J.

1995-01-01

First years after the treatment (in 1987) of forest soil with mineral fertilizers and powdered oil-shale ash in a heavily damaged 50-year-old Scots pine ecosystem showed a comparatively small effect (B<0.95) of liming on the stand characters. However, in comparison with the effect of only NPK fertilization on the volume growth and the health state of trees, liming (NPK+oil-shale ash) tended to increase the positive influence of fertilizers. Under the influence of oil-shale ash the mortality of the trees was lower, the density of the stand rose more, and the mean radial increment of trees was by 26% greater than after the NPK treatment without a lime agent. On the whole, the effect of oil-shale ash liming on the growth and health condition of the pine stand was not high. However, the first results of its experimental use on mineral forest soil cannot serve as the basis for essential conclusions. Still, the results give us some assurance to continue our experimental work with powdered oil-shale ash in forests with the purpose of regulating the high acidity of forest soils in some sites to gain positive shifts in the forest life. Taking into account the low price of the powdered oil-shale ash and the plentiful resources of this liming material in Estonia, even a small trend towards an improvement of forest condition on poor sandy soils would be a satisfactory final result of the work. It is essential to note that oil-shale ash is not only a simple liming material, but also a lime fertilizer consisting of numerous chemical elements necessary for plant growth. 2 tabs., 3 figs., 18 refs

Habitat Preferences of Boros schneideri (Coleoptera: Boridae) in the Natural Tree Stands of the Białowieża Forest

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Gutowski, Jerzy M.; Sućko, Krzysztof; Zub, Karol; Bohdan, Adam

2014-01-01

Abstract We analyzed habitat requirements of Boros schneideri (Panzer, 1796) (Coleoptera: Boridae) in the natural forests of the continental biogeographical region, using data collected in the Białowieża Forest. This species has been found on the six host trees, but it preferred dead, standing pine trees, characterized by large diameter, moderately moist and moist phloem but avoided trees in sunny locations. It occurred mostly in mesic and wet coniferous forests. This species demonstrated preferences for old tree stands (over 140-yr old), and its occurrence in younger tree-stand age classes (minimum 31–40-yr old) was not significantly different from random distribution. B. schneideri occupied more frequently locations distant from the forest edge, which were less affected by logging. Considering habitat requirements, character of occurrence, and decreasing number of occupied locations in the whole range of distribution, this species can be treated as relict of primeval forests. PMID:25527586

Environmental Impacts to Residual Stand Damage due to Logging Operations in Hyrcanian Forest

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Meghdad JOURGHOLAMI

2012-08-01

Full Text Available The development of harvesting systems aims to provide physically feasible, economically viable, and environmentally sound solutions. Residual stand-damage data have been collected from a mixed broadleaved stand in Kheyrud area in Hyrcanian forest in the northern of Iran. After the harvesting operations, for all trees, damage to the bole, roots, extent of the damage, wounding patterns, size and distribution was assessed using stratified systematic sampling with a random start and fixed area plots. Results show that wounding occurred on 16.4% of the remaining trees, but the severity of wounding varied significantly by species. Forty-six percent of wounding for all species combined was considered as small size. The greatest average amount of damage, to a bole, occurred along the first 1m up from the ground and also within 3m of the skid trail centerline (86.4%. Gouges were present on 79% of all scars. The stratification of the study unit would effectively improve accuracy of stand damage surveys. Selection of the appropriate method for damage reduction to trees adjacent skid trails was crucial. According to the results, skidding damage cannot be completely avoided in practice. We suggest that the education and the entertainment of the foresters and workers in forest would be enhanced and the injuries could be explained before the harvesting to the workers. In such a way the damages would be less in the future.

Abundance of juvenile eastern box turtles in manages forest stands

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Z. Felix; Y. Wang; H. Czech; C. Schweitzer

2008-01-01

Between 2002 and 2005, we used drift fences and artificial pools to sample juvenile eastern box turtles (Terrapene carolina) in northeastern Alabama in forest stands experimentally treated to retain various amounts of overstory trees—clear-cuts and those with 25%–50% and 75%–100% of trees retained.We captured juvenile turtles only in clear-cut and 25%–50% retention...

Semantic segmentation of forest stands of pure species combining airborne lidar data and very high resolution multispectral imagery

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Dechesne, Clément; Mallet, Clément; Le Bris, Arnaud; Gouet-Brunet, Valérie

2017-04-01

Forest stands are the basic units for forest inventory and mapping. Stands are defined as large forested areas (e.g., ⩾ 2 ha) of homogeneous tree species composition and age. Their accurate delineation is usually performed by human operators through visual analysis of very high resolution (VHR) infra-red images. This task is tedious, highly time consuming, and should be automated for scalability and efficient updating purposes. In this paper, a method based on the fusion of airborne lidar data and VHR multispectral images is proposed for the automatic delineation of forest stands containing one dominant species (purity superior to 75%). This is the key preliminary task for forest land-cover database update. The multispectral images give information about the tree species whereas 3D lidar point clouds provide geometric information on the trees and allow their individual extraction. Multi-modal features are computed, both at pixel and object levels: the objects are individual trees extracted from lidar data. A supervised classification is then performed at the object level in order to coarsely discriminate the existing tree species in each area of interest. The classification results are further processed to obtain homogeneous areas with smooth borders by employing an energy minimum framework, where additional constraints are joined to form the energy function. The experimental results show that the proposed method provides very satisfactory results both in terms of stand labeling and delineation (overall accuracy ranges between 84 % and 99 %).

Chemical composition of the humus layer, mineral soil and soil solution of 200 forest stands in the Netherlands in 1995

NARCIS (Netherlands)

Leeters, E.E.J.M.; Vries, de W.

2001-01-01

A nationwide assessment of the chemical composition of the soil solid phase and the soil solution in the humus layer and two mineral layers (0-10 cm and 10-30 cm) was made for 200 forest stands in the year 1995. The stands were part of the national forest inventory on vitality, included seven tree

The influence of sampling unit size and spatial arrangement patterns on neighborhood-based spatial structure analyses of forest stands

Energy Technology Data Exchange (ETDEWEB)

Wang, H.; Zhang, G.; Hui, G.; Li, Y.; Hu, Y.; Zhao, Z.

2016-07-01

Aim of study: Neighborhood-based stand spatial structure parameters can quantify and characterize forest spatial structure effectively. How these neighborhood-based structure parameters are influenced by the selection of different numbers of nearest-neighbor trees is unclear, and there is some disagreement in the literature regarding the appropriate number of nearest-neighbor trees to sample around reference trees. Understanding how to efficiently characterize forest structure is critical for forest management. Area of study: Multi-species uneven-aged forests of Northern China. Material and methods: We simulated stands with different spatial structural characteristics and systematically compared their structure parameters when two to eight neighboring trees were selected. Main results: Results showed that values of uniform angle index calculated in the same stand were different with different sizes of structure unit. When tree species and sizes were completely randomly interspersed, different numbers of neighbors had little influence on mingling and dominance indices. Changes of mingling or dominance indices caused by different numbers of neighbors occurred when the tree species or size classes were not randomly interspersed and their changing characteristics can be detected according to the spatial arrangement patterns of tree species and sizes. Research highlights: The number of neighboring trees selected for analyzing stand spatial structure parameters should be fixed. We proposed that the four-tree structure unit is the best compromise between sampling accuracy and costs for practical forest management. (Author)

Forest bioenergy or forest carbon? Assessing trade-offs in greenhouse gas mitigation with wood-based fuels.

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McKechnie, Jon; Colombo, Steve; Chen, Jiaxin; Mabee, Warren; MacLean, Heather L

2011-01-15

The potential of forest-based bioenergy to reduce greenhouse gas (GHG) emissions when displacing fossil-based energy must be balanced with forest carbon implications related to biomass harvest. We integrate life cycle assessment (LCA) and forest carbon analysis to assess total GHG emissions of forest bioenergy over time. Application of the method to case studies of wood pellet and ethanol production from forest biomass reveals a substantial reduction in forest carbon due to bioenergy production. For all cases, harvest-related forest carbon reductions and associated GHG emissions initially exceed avoided fossil fuel-related emissions, temporarily increasing overall emissions. In the long term, electricity generation from pellets reduces overall emissions relative to coal, although forest carbon losses delay net GHG mitigation by 16-38 years, depending on biomass source (harvest residues/standing trees). Ethanol produced from standing trees increases overall emissions throughout 100 years of continuous production: ethanol from residues achieves reductions after a 74 year delay. Forest carbon more significantly affects bioenergy emissions when biomass is sourced from standing trees compared to residues and when less GHG-intensive fuels are displaced. In all cases, forest carbon dynamics are significant. Although study results are not generalizable to all forests, we suggest the integrated LCA/forest carbon approach be undertaken for bioenergy studies.

Stand density index as a tool to assess the maximization of forest carbon and biomass

Science.gov (United States)

Christopher W. Woodall; Anthony W. D’Amato; John B. Bradford; Andrew O. Finley

2012-01-01

Given the ability of forests to mitigate greenhouse gas emissions and provide feedstocks to energy utilities, there is an emerging need to assess forest biomass/carbon accretion opportunities over large areas. Techniques for objectively quantifying stand stocking of biomass/carbon are lacking for large areas given the complexity of tree species composition in the U.S....

Forest types of the "Argentino River Valley" Natural Reserve

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Bagnato S

2008-09-01

Full Text Available Forest classification is a fundamental target for understanding forest stand dynamics and for sustainable management strategy applications. In this paper the methodological approach of forest types, already used in other Italians region, was applied for the classification of the RNO "Argentino River Valley" (southern Apennine, Italy. This study has been organized in 4 steps: 1 bibliographic analysis and collection of the acquired knowledge; 2 preliminary verification of forest types in the field; 3 description of the different units; 4 final validation of typological units. Using this approach we have characterized 9 categories and 12 forest types units. The description of each units has been filed as cards, where information of different nature is summarized and related to the organization of the typological units, to its location, to the description of the qualitative indicators (disturbances, cohort, mortality, natural dynamic tendencies, SDT, CWD etc. and quantitative indicators (dbh, average height, current annual increment, etc., to the functioning and the current management. For a better understanding of types functioning, "sylvology models" based on the "Spatial Pattern of Relative Collective Interaction" (PSICR and on the principal characteristics influencing and characterizing forest stand dynamics (availability of resources, type and frequency of disturbances, stand development, etc. have been singled out and proposed. The "forest types map" and other maps useful for the management of forest resources have been obtained. Moreover, data collected did allow to formulate several hypotheses on sustainable management.

Stand Structure, Productivity and Carbon Sequestration Potential of Oak Dominated Forests in Kumaun Himalaya

OpenAIRE

Bijendra Lal; L.S. Lodhiyal

2016-01-01

Present study deals with stand structure, biomass, productivity and carbon sequestration in oak dominated forests mixed with other broad leaved tree species. The sites of studied forests were located in Nainital region between 29058’ N lat. and 79028’ E long at 1500-2150 m elevation. Tree density of forests ranged from 980-1100 ind.ha-1. Of this, oak trees shared 69-97%. The basal area of trees was 31.81 to 63.93 m2 ha-1. R. arboreum and Q. floribunda shared maximum basal area 16.45 and 16.32...

Forest development and carbon dynamics after mountain pine beetle outbreaks

Science.gov (United States)

E. Matthew. Hansen

2014-01-01

Mountain pine beetles periodically infest pine forests in western North America, killing many or most overstory pine stems. The surviving secondary stand structure, along with recruited seedlings, will form the future canopy. Thus, even-aged pine stands become multiaged and multistoried. The species composition of affected stands will depend on the presence of nonpines...

Forest stand dynamics of shortleaf pine in the Ozarks

Science.gov (United States)

David R. Larsen

2007-01-01

Much has been written on the management of shortleaf pine in the Ozarks (Brinkman et al. 1965, Brinkman 1967, Brinkman and Smith 1968, Seidel and Rogers 1965, Seidel and Rogers 1966). In large portions of the Ozarks, shortleaf pine does not grow in pure stands but rather in mixes with various oak species. These mixes present unique challenges in finding the set of...

The dynamics of pine forests in Prebaikalia under anthropogenic impact

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T. A. Mikhailova

2017-02-01

Full Text Available Analyzed and generalized were the results of prolonged (10–25 years monitoring of condition pine Pinus sylvestris L. forests affected by technogenic pollution and high recreation load in the South Prebaikalia. The results show that both factors have similarity in the stress effect on pine tree-stands, as confirmed by alteration in morphometric parameters of tree assimilating phytomass, decrease in photosynthetic pigments level, as well as by disturbance the nutrient elements proportions in the needles. As tree crown defoliation level reaches 65–70 %, the morphometric parameters for shoots and needles are found to decrease the background level by in 1.3–4.5 times. Under technogenic pollution, the needles’ chlorophylls sum was reduced 2.8–3.5 times, level of carotenoides – to 3.9 times maximum in comparison with the background needles while under high recreation load the green pigments content was reduced 1.9–5.7 times, carotenoids content – to 5.5 times. There is a imbalance in quantitative proportions between nutritional elements under any type of stress, N : P : K proportion changes due to increase of nitrogen level and reduction of phosphorus and potassium level. Index of tree-stand vital condition was calculated on the basis of the representative parameters to analyze the long forest dynamics. Significant reduction was shown in the index in the present time and correspondingly the obvious tendency to pine forest decline in the territories polluted by Irkutsk, Shelekhov, and Angarsk-Usolie industrial centers. At the same time near Cheremkhovo and Sayansk-Zima centers there are not heavy changes in the forest’s condition; during long time a middle level of weakening is registered but in the distance 20 km – a low level of weakening. In the territories characterized by a high recreation load, a sharp trend to declining pine tree-stands vital condition was found, and most clearly it is expressed in the towns of Khuzhir (Olkhon

Biogeographical patterns of biomass allocation in leaves, stems, and roots in China's forests.

Science.gov (United States)

Zhang, Hao; Wang, Kelin; Xu, Xianli; Song, Tongqing; Xu, Yanfang; Zeng, Fuping

2015-11-03

To test whether there are general patterns in biomass partitioning in relation to environmental variation when stand biomass is considered, we investigated biomass allocation in leaves, stems, and roots in China's forests using both the national forest inventory data (2004-2008) and our field measurements (2011-2012). Distribution patterns of leaf, stem, and root biomass showed significantly different trends according to latitude, longitude, and altitude, and were positively and significantly correlated with stand age and mean annual precipitation. Trade-offs among leaves, stems, and roots varied with forest type and origin and were mainly explained by stand biomass. Based on the constraints of stand biomass, biomass allocation was also influenced by forest type, origin, stand age, stand density, mean annual temperature, precipitation, and maximum temperature in the growing season. Therefore, after stand biomass was accounted for, the residual variation in biomass allocation could be partially explained by stand characteristics and environmental factors, which may aid in quantifying carbon cycling in forest ecosystems and assessing the impacts of climate change on forest carbon dynamics in China.

Increased drought impacts on temperate rainforests from southern South America: results of a process-based, dynamic forest model.

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Alvaro G Gutiérrez

Full Text Available Increased droughts due to regional shifts in temperature and rainfall regimes are likely to affect forests in temperate regions in the coming decades. To assess their consequences for forest dynamics, we need predictive tools that couple hydrologic processes, soil moisture dynamics and plant productivity. Here, we developed and tested a dynamic forest model that predicts the hydrologic balance of North Patagonian rainforests on Chiloé Island, in temperate South America (42°S. The model incorporates the dynamic linkages between changing rainfall regimes, soil moisture and individual tree growth. Declining rainfall, as predicted for the study area, should mean up to 50% less summer rain by year 2100. We analysed forest responses to increased drought using the model proposed focusing on changes in evapotranspiration, soil moisture and forest structure (above-ground biomass and basal area. We compared the responses of a young stand (YS, ca. 60 years-old and an old-growth forest (OG, >500 years-old in the same area. Based on detailed field measurements of water fluxes, the model provides a reliable account of the hydrologic balance of these evergreen, broad-leaved rainforests. We found higher evapotranspiration in OG than YS under current climate. Increasing drought predicted for this century can reduce evapotranspiration by 15% in the OG compared to current values. Drier climate will alter forest structure, leading to decreases in above ground biomass by 27% of the current value in OG. The model presented here can be used to assess the potential impacts of climate change on forest hydrology and other threats of global change on future forests such as fragmentation, introduction of exotic tree species, and changes in fire regimes. Our study expands the applicability of forest dynamics models in remote and hitherto overlooked regions of the world, such as southern temperate rainforests.

Increased drought impacts on temperate rainforests from southern South America: results of a process-based, dynamic forest model.

Science.gov (United States)

Gutiérrez, Alvaro G; Armesto, Juan J; Díaz, M Francisca; Huth, Andreas

2014-01-01

Increased droughts due to regional shifts in temperature and rainfall regimes are likely to affect forests in temperate regions in the coming decades. To assess their consequences for forest dynamics, we need predictive tools that couple hydrologic processes, soil moisture dynamics and plant productivity. Here, we developed and tested a dynamic forest model that predicts the hydrologic balance of North Patagonian rainforests on Chiloé Island, in temperate South America (42°S). The model incorporates the dynamic linkages between changing rainfall regimes, soil moisture and individual tree growth. Declining rainfall, as predicted for the study area, should mean up to 50% less summer rain by year 2100. We analysed forest responses to increased drought using the model proposed focusing on changes in evapotranspiration, soil moisture and forest structure (above-ground biomass and basal area). We compared the responses of a young stand (YS, ca. 60 years-old) and an old-growth forest (OG, >500 years-old) in the same area. Based on detailed field measurements of water fluxes, the model provides a reliable account of the hydrologic balance of these evergreen, broad-leaved rainforests. We found higher evapotranspiration in OG than YS under current climate. Increasing drought predicted for this century can reduce evapotranspiration by 15% in the OG compared to current values. Drier climate will alter forest structure, leading to decreases in above ground biomass by 27% of the current value in OG. The model presented here can be used to assess the potential impacts of climate change on forest hydrology and other threats of global change on future forests such as fragmentation, introduction of exotic tree species, and changes in fire regimes. Our study expands the applicability of forest dynamics models in remote and hitherto overlooked regions of the world, such as southern temperate rainforests.

Nitrogen limitation of growth and nutrient dynamics in a disturbed mangrove forest, Indian River Lagoon, Florida

Science.gov (United States)

Feller, Ilka C.; Whigham, D.F.; McKee, K.L.; Lovelock, C.E.

2003-01-01

The objectives of this study were to determine effects of nutrient enrichment on plant growth, nutrient dynamics, and photosynthesis in a disturbed mangrove forest in an abandoned mosquito impoundment in Florida. Impounding altered the hydrology and soil chemistry of the site. In 1997, we established a factorial experiment along a tree-height gradient with three zones, i.e., fringe, transition, dwarf, and three fertilizer treatment levels, i.e., nitrogen (N), phosphorus (P), control, in Mosquito Impoundment 23 on the eastern side of Indian River. Transects traversed the forest perpendicular to the shoreline, from a Rhizophora mangle-dominated fringe through an Avicennia germinans stand of intermediate height, and into a scrub or dwarf stand of A. germinans in the hinterland. Growth rates increased significantly in response to N fertilization. Our growth data indicated that this site is N-limited along the tree-height gradient. After 2 years of N addition, dwarf trees resembled vigorously growing saplings. Addition of N also affected internal dynamics of N and P and caused increases in rates of photosynthesis. These findings contrast with results for a R. mangle-dominated forest in Belize where the fringe is N-limited, but the dwarf zone is P-limited and the transition zone is co-limited by N and P. This study demonstrated that patterns of nutrient limitation in mangrove ecosystems are complex, that not all processes respond similarly to the same nutrient, and that similar habitats are not limited by the same nutrient when different mangrove forests are compared.

Management impacts on forest floor and soil organic carbon in northern temperate forests of the US

Science.gov (United States)

Coeli M. Hoover

2011-01-01

The role of forests in the global carbon cycle has been the subject of a great deal of research recently, but the impact of management practices on forest soil dynamics at the stand level has received less attention. This study used six forest management experimental sites in five northern states of the US to investigate the effects of silvicultural treatments (light...

Comparison of riparian and upland forest stand structure and fuel loads in beetle infested watersheds, southern Rocky Mountains

Science.gov (United States)

Kathleen A. Dwire; Robert Hubbard; Roberto Bazan

2015-01-01

Extensive outbreaks of mountain pine beetle (MPB), spruce beetle (SB), and other insects are altering forest stand structure throughout western North America, and thereby contributing to the heterogeneity of fuel distribution. In forested watersheds, conifer-dominated riparian forests frequently occur as narrow linear features in the landscape mosaic and contribute to...

Floristic Study of Buxus hyrcana Stands in the Western Forests of Haraz District, Amol

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S. Hosseinzadeh

2017-06-01

Full Text Available Floristic composition of boxwood (Buxus hyrcana Pojark stands in the forests of Western Haraz, distributed at the altitudinal range of 250 to 1,200 m asl, was investigated by field-walk method. Results showed that the flora of this area includes 50 families, 69 genera, and 78 plant species. Rosaceae, Orchidaceae, Dryopteridaceae, Lamiaceae and Aspleniaceae are the greatest families in this area. Chorological studies showed that the largest proportion of the flora is related to Euro-Siberian region (56.4%. Cryptophytes (32 species, Phanerophytes (26 sp. and Hemicryptophytes (16 sp., which are compromising 44%, 33.3% and 20.5% of the flora, were the most important structure groups of the biological spectrum. Abundance of Cryptophytes with Phanerophytes and Hemicryptophytes in these forests implys that there is a temperate climate with cold winter, frequently rainfall and relatively cool summer, which are suitable for growing temperate forest. Frequent occurrence of Prunus Laurocerasus trees with Daneae racemosa as a woody understory species especially in the upper parts of the studied area accompany by absence of Therophytes and relatively well distribution of ferns species, especially Asplenium scolopendrium, also implys high, favorable, moisture conditions without any disturbances in Box tree stands of these forests.

Seasonal Pattern of Decomposition and N, P, and C Dynamics in Leaf litter in a Mongolian Oak Forest and a Korean Pine Plantation

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Jaeeun Sohng

2014-10-01

Full Text Available Distinct seasons and diverse tree species characterize temperate deciduous forests in NE Asia, but large areas of deciduous forests have been converted to conifer plantations. This study was conducted to understand the effects of seasons and tree species on leaf litter decomposition in a temperate forest. Using the litterbag method, the decomposition rate and nitrogen, phosphorous, and carbon dynamics of Mongolian oak (Quercus mongolica, Korean pine (Pinus koraiensis, and their mixed leaf litter were compared for 24 months in a Mongolian oak stand, an adjacent Korean pine plantation, and a Mongolian oak—Korean pine mixed stand. The decomposition rates of all the leaf litter types followed a pattern of distinct seasonal changes: most leaf litter decomposition occurred during the summer. Tree species was less influential on the leaf litter decomposition. The decomposition rates among different leaf litter types within the same stand were not significantly different, indicating no mixed litter effect. The immobilization of leaf litter N and P lasted for 14 months. Mongolian oak leaf litter and Korean pine leaf litter showed different N and P contents and dynamics during the decomposition, and soil P2O5 was highest in the Korean pine plantation, suggesting effects of plantation on soil nutrient budget.

Specifics of stands formation at coalmine dumps in forest-steppe zone

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R. T. Murzakmаtov

2018-02-01

Full Text Available Rock dumps of coalmines have high potential for forest regeneration and environmental capacity, which are dependent on the technology of reclamation and the properties of technogenic soils and grounds. Traditional forestry methods for obtaining the main criteria of biological indicators of woody vegetation were used in the study as follows: ground seed germination, seedling planting technology, composition and increment of tree stands, root structure, care harvesting of undergrowth, biotopic classification. Natural overgrowing of dumps is dependent on the availability of seeds and conditions for their germination and subsequent growth. Most of the zonal tree and shrub species are able to colonize and grow on the coalmine dumps. Mineralization of the dumps surfaces without rich soil stratum, porosity of the upper horizon of lithostratum, and low nutrient content (nitrogen give benefits in the growth and subsequent formation of birch, pine and sea-buckthorn stands. Afforestation is the cheapest and most effective method of biological reclamation. The analysis of artificial reforestation shows the probability of targeted plantation cultivation of various tree species. The use of a wide range of tree and shrub species make it possible to create biologically diverse intrazonal technogenic ecosystems with high recreational and economic productivity. Wildfires spreading out in spring season on herbaceous rags limit the overgrowth of the dumps by forest vegetation. Two-year cyclical increment decline of trees due to provocative spring warming takes place. The zoogenic factor, especially zoo chores distribution of berry plants, has essential value for forest forming process. By the results of forest formation analysis at rock dumps, alveolate-hilly technology of mine reclamation was developed, which allows to significantly improve dumps’ afforestation capacity, their biological posttechnogenic diversity and productivity.

Present state and future trends of pine forests of malam jabba, swat district, Pakistan

International Nuclear Information System (INIS)

Siddiqui, M. F.; Arsalan, M.; Hussain, M. I.; Iqbal, J.; Wahab, M.

2015-01-01

Present state and future trend of pine forests of Malam Jabba, Swat district, Pakistan explored. We focused on vegetation composition, structure, diversity and forests dynamics. Thirteen stands were sampled by Point Centered Quarter method. Among all stands four monospecific forests of Pinus wallichiana attained highest density ha-1 except in one stand where Picea smithiana attained 401 trees ha-1. Unlike density, the basal area m2 ha-1 of these stands varies stand to stand. Based on floristic composition and importance value index, five different communities viz Pinus wallichiana-Picea smithiana; Picea smithiana-Pinus wallichiana; Abies pindrow-Pinus wallichiana; Pinus wallichiana-Abies pindrow; Abies pindrow-Picea smithiana and 4 monospecific forests of Pinus wallichiana were recognized. Size class structure of forests showed marked influence of anthropogenic disturbance because not a single stand showed ideal regeneration pattern (inverse J shape distribution). Future of these forests is worst due to absence trees in small size classes. Gaps are also evident in most of the forest stands. Stand diversity, richness, equitability and Simpson dominance values formulated on single stand basis. Diversity of Abides pindrow and Pinus wallichiana stand was highest because these stand occupied dominant species, while lowest diversity observed in some Pinus wallichiana and Picea smithiana stand as these stands have mark difference between the dominance of two species. In the monospecific forests, the diversity level was zero, suggesting the monopolization of resources by one species or elimination of other tree species in these stands. (author)

Timber, Browse, and Herbage on Selected Loblolly-Shortleaf Pine-Hardwood Forest Stands

Science.gov (United States)

Gale L. Wolters; Alton Martin; Warren P. Clary

1977-01-01

A thorough vegetation inventory was made on loblolly-shortleaf pine-hardwood stands scheduled by forest industry for clearcutting, site preparation, and planting to pine in north central Louisiana and southern Arkansas. Overstory timber, on the average, contained about equal proportions of softwood and hardwood basal area. Browse plants ranged from 5,500 to over 70,...

Accounting for density reduction and structural loss in standing dead trees: Implications for forest biomass and carbon stock estimates in the United States

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Domke Grant M

2011-11-01

Full Text Available Abstract Background Standing dead trees are one component of forest ecosystem dead wood carbon (C pools, whose national stock is estimated by the U.S. as required by the United Nations Framework Convention on Climate Change. Historically, standing dead tree C has been estimated as a function of live tree growing stock volume in the U.S.'s National Greenhouse Gas Inventory. Initiated in 1998, the USDA Forest Service's Forest Inventory and Analysis program (responsible for compiling the Nation's forest C estimates began consistent nationwide sampling of standing dead trees, which may now supplant previous purely model-based approaches to standing dead biomass and C stock estimation. A substantial hurdle to estimating standing dead tree biomass and C attributes is that traditional estimation procedures are based on merchantability paradigms that may not reflect density reductions or structural loss due to decomposition common in standing dead trees. The goal of this study was to incorporate standing dead tree adjustments into the current estimation procedures and assess how biomass and C stocks change at multiple spatial scales. Results Accounting for decay and structural loss in standing dead trees significantly decreased tree- and plot-level C stock estimates (and subsequent C stocks by decay class and tree component. At a regional scale, incorporating adjustment factors decreased standing dead quaking aspen biomass estimates by almost 50 percent in the Lake States and Douglas-fir estimates by more than 36 percent in the Pacific Northwest. Conclusions Substantial overestimates of standing dead tree biomass and C stocks occur when one does not account for density reductions or structural loss. Forest inventory estimation procedures that are descended from merchantability standards may need to be revised toward a more holistic approach to determining standing dead tree biomass and C attributes (i.e., attributes of tree biomass outside of sawlog

Biogeographical patterns of biomass allocation in leaves, stems, and roots in China’s forests

Science.gov (United States)

Zhang, Hao; Wang, Kelin; Xu, Xianli; Song, Tongqing; Xu, Yanfang; Zeng, Fuping

2015-01-01

To test whether there are general patterns in biomass partitioning in relation to environmental variation when stand biomass is considered, we investigated biomass allocation in leaves, stems, and roots in China’s forests using both the national forest inventory data (2004–2008) and our field measurements (2011–2012). Distribution patterns of leaf, stem, and root biomass showed significantly different trends according to latitude, longitude, and altitude, and were positively and significantly correlated with stand age and mean annual precipitation. Trade-offs among leaves, stems, and roots varied with forest type and origin and were mainly explained by stand biomass. Based on the constraints of stand biomass, biomass allocation was also influenced by forest type, origin, stand age, stand density, mean annual temperature, precipitation, and maximum temperature in the growing season. Therefore, after stand biomass was accounted for, the residual variation in biomass allocation could be partially explained by stand characteristics and environmental factors, which may aid in quantifying carbon cycling in forest ecosystems and assessing the impacts of climate change on forest carbon dynamics in China. PMID:26525117

Tree microhabitat structures as indicators of biodiversity in Douglas-fir forests of different stand ages and management histories in the Pacific Northwest, U.S.A.

Science.gov (United States)

Alexa K. Michel; Susanne. Winter

2009-01-01

In this study, microhabitat structures in Douglas-fir (Pseudotsuga menziesii) forests were defined and their frequency and abundance in natural stands and stands of varying active management histories and stand ages was compared. Indicator microhabitat structures for natural forests were determined and the relationship of the abundance of...

Modelling recolonization of second-growth forest stands by the north american red squirrel Tamiasciurus hudsonicus.

Science.gov (United States)

Nyquist, B; Tyson, R; Larsen, K

2007-05-01

In this paper, we present a model for source-sink population dynamics where the locations of source and sink habitats change over time. We do this in the context of the population dynamics of the North American red squirrel, Tamiasciurus hudsonicus, within a forest environment subject to harvesting and regrowth. Harvested patches of forest are initially sinks, then eventually become source habitat again as the forest regrows. At the same time, each harvested patch is gradually recolonized by squirrels from other forest patches. We are interested in the interaction of forest harvesting dynamics with squirrel population dynamics. This depends on the harvesting schedule, and on the choices squirrels make when deciding whether to settle in a mature forest patch or in a recently harvested patch. We find that the time it takes for a second-growth forest patch to be recolonized at the mature forest level is longer than the time required for the habitat quality to be restored to the mature forest level. We also notice that recolonization pressure decreases squirrel populations in neighbouring patches. The connectivity between forest patches and the cutting schedule used also affect the time course of recolonization and steady-state population levels.

Soil microbial biomass under pine forests in the north-western Spain: influence of stand age, site index and parent material

Energy Technology Data Exchange (ETDEWEB)

Mahia, J.; Perez-Ventura, L.; Cabaneiro, A.; Diaz-Ravina, M.

2006-07-01

The effects of stand age, site index and parent material on soil biochemical properties related to biomass (extractable C, microbial C and metabolic quotient) were examined in the 0-15 cm mineral soil layers of Pinus pinaster and Pinus sylvestris stand from NW Spain. Two productivity levels (low and high site index), two ages (young and old) and two parent soil materials (granite and acid schists) were considered. The data indicated that there were differences in microbial parameters in soils under different species. In general in P. pinaster forest higher values of biochemical parameters expressed on organic C basis, were observed in the stands of high site index as compared with the low ones; in contrast, in P. sylvestris no differences among stand site index were detected. In both species different results were also observed depending on parent material and a significant effect of stand age was detected for extractable C and microbial C in P. pinaster forest developed over granite. The data seem to indicate that measured parameters may have the potential to be used as indicators of the effect of forest management on soil organic matter quality. (Author) 25 refs.

ROOT GROWTH AND TURNOVER IN DIFFERENT AGED PONDEROSA PINE STANDS IN OREGON, USA

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The impacts of pollution and climate change on soil carbon dynamics are poorly understood, in part due to a lack of information regarding root production and turnover in natural ecosystems. In order to examine how root dynamics change with stand age in ponderosa pine forests (...

Dynamics and ecological consequences of the 2013−2014 koa moth outbreak at Hakalau Forest National Wildlife Refuge.

Science.gov (United States)

Banko, Paul C.; Peck, Robert W.; Yelenik, Stephanie G.; Paxton, Eben H.; Bonaccorso, Frank J.; Montoya-Aiona, Kristina; Foote, David

2014-01-01

A massive outbreak of the koa moth (Geometridea: Scotorythra paludicola) defoliated more than a third of the koa (Acacia koa) forest on Hawai‘i Island during 2013−2014. This was the largest koa moth outbreak ever recorded and the first on the island since 1953. The outbreak spread to sites distributed widely around the island between 800−2,000 m elevation and in wet rainforest to dry woodland habitats. We monitored the outbreak at two windward forest sites (Laupāhoehoe and Saddle Road Kīpuka) and one leeward forest site (Kona), and we studied the dynamics of the outbreak and its impacts on the forest ecosystem at Hakalau Forest National Wildlife Refuge, our higher elevation windward site. Study sites at Hakalau included two stands of koa that were planted (reforestation stands) in former cattle pastureland about 20 years earlier and two stands of koa that were dominated by ‘ōhi‘a (Metrosideros polymorpha) and that were naturally recovering from cattle grazing (forest stands). We observed one outbreak at Hakalau, multiple outbreaks at the two other windward sites, but no outbreak at the leeward site. Caterpillars at Hakalau reached peak estimated abundances of more than 250,000 per tree and 18,000,000 per hectare, and they removed between 64−93% of the koa canopy in managed forest stands. Defoliation was more extensive in naturally recovering forest, where ‘ōhi‘a dominated and koa was less abundant, compared to the planted stands, where koa density was high. Koa trees were still growing new foliage six months after being defoliated, and leaves were produced in greater proportion to phyllodes, especially by small koa (≤ 8 cm dbh) and by larger trees in forest stands, where light levels may have remained relatively low after defoliation due to the high cover of ‘ōhi‘a. Small branches of many trees apparently died, and canopy regrowth was absent or low in 9% of koa trees and seedlings, which indicates the likely level of mortality. Between 2

From a tree to a stand in Finnish boreal forests: biomass estimation and comparison of methods

OpenAIRE

Liu, Chunjiang

2009-01-01

There is an increasing need to compare the results obtained with different methods of estimation of tree biomass in order to reduce the uncertainty in the assessment of forest biomass carbon. In this study, tree biomass was investigated in a 30-year-old Scots pine (Pinus sylvestris) (Young-Stand) and a 130-year-old mixed Norway spruce (Picea abies)-Scots pine stand (Mature-Stand) located in southern Finland (61º50' N, 24º22' E). In particular, a comparison of the results of different estimati...

Litterfall and litter decomposition in chestnut high forest stands in northern Portugal

Energy Technology Data Exchange (ETDEWEB)

Patricio, M. S.; Nunes, L. F.; Pereira, E. L.

2012-11-01

This research aimed to: estimate the inputs of litterfall; model the decomposition process and assess the rates of litter decay and turnover; study the litter decomposition process and dynamics of nutrients in old chestnut high forests. This study aimed to fill a gap in the knowledge of chestnut decomposition process as this type of ecosystems have never been modeled and studied from this point of view in Portugal. The study sites are located in the mountains of Marao, Padrela and Bornes in a west-to-east transect, across northern Portugal, from a more-Atlantic-to-lessmaritime influence. This research was developed on old chestnut high forests for quality timber production submitted to a silviculture management close-to-nature. We collected litterfall using littertraps and studied decomposition of leaf and bur litter by the nylon net bag technique. Simple and double exponential models were used to describe the decomposition of chestnut litterfall incubated in situ during 559 days. The results of the decomposition are discussed in relation to the initial litter quality (C, N, P, K, Ca, Mg) and the decomposition rates. Annually, the mature chestnut high-forest stands (density 360-1,260 tree ha1, age 55-73 years old) restore 4.9 Mg DM ha–1 of litter and 2.6 Mg ha{sup -}1 yr{sup -}1 of carbon to the soil. The two-component litter decay model proved to be more biologically realistic, providing a decay rate for the fast initial stage (46-58 yr{sup -}1for the leaves and 38-42 yr{sup -}1for the burs) and a decay rate related to the recalcitrant pool (0.45-0.60 yr{sup -}1for the leaves and 0.22-0.36 yr{sup -}1for the burs). This study pointed to some decay patterns and release of bioelements by the litterfall which can be useful for calibrating existing models and indicators of sustainability to improve both silvicultural and environmental approaches for the management of chestnut forests. (Author) 45 refs.

Water and Energy Balances of Loblolly Pine Plantation Forests during a Full Stand Rotation

Science.gov (United States)

Sun, G.; Mitra, B.; Domec, J. C.; Gavazi, M.; Yang, Y.; Tian, S.; Zietlow, D.; McNulty, S.; King, J.; Noormets, A.

2017-12-01

Loblolly pine (Pinus taeda) plantations in the southern U.S. are well recognized for their ecosystem services in supplying clean and stable water and mitigating climate change through carbon sequestration and solar energy partitioning. Since 2004, we have monitored energy, water, and carbon fluxes in a chronosequence of three drained loblolly pine plantations using integrated methods that include eddy covariance, sap flux, watershed hydrometeorology, remote sensing, and process-based simulation modeling. Study sites were located on the eastern North Carolina coastal plain, representing highly productive ecosystems with high groundwater table, and designated in the Ameriflux network as NC1 (0-10 year old), NC2 (12-25 year old) and NC3 (0-3 years old). The 13-year study spanned a wide range of annual precipitation (900-1600 mm/yr) including two exceptionally dry years during 2007-2008. We found that the mature stand (NC2) had higher net radiation (Rn) flux due to its lower albedo (α =0.11-12), compared with the young stands (NC1, NC3) (α=0.15-0.18). Annually about 75%-80% of net radiation was converted to latent heat in the pine plantations. In general, the mature stand had higher latent heat flux (LE) (i.e. evapotranspiration (ET)) rates than the young stands, but ET rates were similar during wet years when the groundwater table was at or near the soil surface. During a historic drought period (i.e., 2007-2008), total stand annual ET exceeded precipitation, but decreased about 30% at NC2 when compared to a normal year (e.g., 2006). Field measurements and remote sensing-based modeling suggested that annual ET rates increased linearly from planting age (about 800 mm) to age 15 (about 1050 mm) and then stabilized as stand leaf area index leveled-off. Over a full stand rotation, approximately 70% (young stand) to 90% (mature stand) of precipitation was returned to the atmosphere through ET. We conclude that both climatic variability and canopy structure controlled the

Effect of Forest Structural Change on Carbon Storage in a Coastal Metasequoia glyptostroboides Stand

Directory of Open Access Journals (Sweden)

Xiangrong Cheng

2013-01-01

Full Text Available Forest structural change affects the forest’s growth and the carbon storage. Two treatments, thinning (30% thinning intensity and underplanting plus thinning, are being implemented in a coastal Metasequoia glyptostroboides forest shelterbelt in Eastern China. The vegetation carbon storage significantly increased in the underplanted and thinned treatments compared with that in the unthinned treatment (P0.05. The soil light fraction organic carbon (LFOC was significantly higher at the 0–15 cm soil layer in the thinned and underplanted stands compared with that in the unthinned stand (P<0.05. The soil respiration of the underplanted treatment was significantly higher than that of the unthinned treatment only in July (P<0.05. This study concludes that 30% thinning and underplanting after thinning could be more favorable to carbon sequestration for M. glyptostroboides plantations in the coastal areas of Eastern China.

Stand-Level Gas-Exchange Responses to Seasonal Drought in Very Young Versus Old Douglas-fir Forests of the Pacific Northwest, USA

Energy Technology Data Exchange (ETDEWEB)

Wharton, S; Schroeder, M; Bible, K; Falk, M; Paw U, K T

2009-02-23

This study examines how stand age affects ecosystem mass and energy exchange response to seasonal drought in three adjacent Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests. The sites include two early seral stands (ES) (0-15 years old) and an old-growth (OG) ({approx} 450-500) forest in the Wind River Experiment Forest, Washington, USA. We use eddy covariance flux measurements of carbon dioxide (F{sub NEE}), latent energy ({lambda}E) and sensible heat (H) to derive evapotranspiration rate (E{sub T}), bowen ratio ({beta}), water use efficiency (WUE), canopy conductance (G{sub c}), the Priestley-Taylor coefficient ({alpha}) and a canopy decoupling factor ({Omega}). The canopy and bulk parameters are examined to see how ecophysiological responses to water stress, including changes in available soil water ({theta}{sub r}) and vapor pressure deficit ({delta}e) differ among the two forest successional-stages. Despite very different rainfall patterns in 2006 and 2007, we observed distinct successional-stage relationships between E{sub T}, {alpha}, and G{sub c} to {delta}e and {theta}{sub r} during both years. The largest stand differences were (1) higher morning G{sub c} (> 10 mm s{sup -1}) at the OG forest coinciding with higher CO{sub 2} uptake (F{sub NEE} = -9 to -6 {micro}mol m{sup -2} s{sup -1}) but a strong negative response in G{sub c} to moderate {delta}e later in the day and a subsequent reduction in E{sub T}, and (2) higher E{sub T} at the ES stands because midday canopy conductance did not decrease until very low water availability levels (<30%) were reached at the end of the summer. Our results suggest that early seral stands are more likely than mature forests to experience declines in production if the summer drought becomes longer or intensifies because water conserving ecophysiological responses were only observed at the very end of the seasonal drought period in the youngest stands.

Detecting Multi-layered Forest Stands Using High Density Airborne LiDAR Data. GI_Forum|GI_Forum 2015 – Geospatial Minds for Society|

OpenAIRE

Schultz, Alfred; Mund, Jan-Peter; Körner, Michael; Wilke, Robert

2016-01-01

Since two decades, the use of terrestrial laser scanning (TLS) and Airborne Light Detection and Ranging (LIDAR) has become very prominent in analysing 3D forest structures (AKAY et al. 2009). The potential of full waveform analysis of high density Airborne LiDAR data (ALS) for the detection and structural analysis of multi-layered forest stands is not yet well investigated (JASKIERNIAK et al. 2011), although ALS data provide exact information on tree heights of multi-layered forest stands usi...

Fire-mediated pathways of stand development in Douglas-fir/western hemlock forests of the Pacific Northwest, USA

Science.gov (United States)

A.J. Tepley; F.J. Swanson; T.A. Spies

2013-01-01

Forests dominated by Douglas-fir and western hemlock in the Pacific Northwest of the United States have strongly influenced concepts and policy concerning old-growth forest conservation. Despite the attention to their old-growth characteristics, a tendency remains to view their disturbance ecology in relatively simple terms, emphasizing infrequent, stand-replacing (SR...

Abiotic and Biotic Soil Characteristics in Old Growth Forests and Thinned or Unthinned Mature Stands in Three Regions of Oregon

Directory of Open Access Journals (Sweden)

David A. Perry

2012-09-01

Full Text Available We compared forest floor depth, soil organic matter, soil moisture, anaerobic mineralizable nitrogen (a measure of microbial biomass, denitrification potential, and soil/litter arthropod communities among old growth, unthinned mature stands, and thinned mature stands at nine sites (each with all three stand types distributed among three regions of Oregon. Mineral soil measurements were restricted to the top 10 cm. Data were analyzed with both multivariate and univariate analyses of variance. Multivariate analyses were conducted with and without soil mesofauna or forest floor mesofauna, as data for those taxa were not collected on some sites. In multivariate analysis with soil mesofauna, the model giving the strongest separation among stand types (P = 0.019 included abundance and richness of soil mesofauna and anaerobic mineralizable nitrogen. The best model with forest floor mesofauna (P = 0.010 included anaerobic mineralizable nitrogen, soil moisture content, and richness of forest floor mesofauna. Old growth had the highest mean values for all variables, and in both models differed significantly from mature stands, while the latter did not differ. Old growth also averaged higher percent soil organic matter, and analysis including that variable was significant but not as strong as without it. Results of the multivariate analyses were mostly supported by univariate analyses, but there were some differences. In univariate analysis, the difference in percent soil organic matter between old growth and thinned mature was due to a single site in which the old growth had exceptionally high soil organic matter; without that site, percent soil organic matter did not differ between old growth and thinned mature, and a multivariate model containing soil organic matter was not statistically significant. In univariate analyses soil mesofauna had to be compared nonparametrically (because of heavy left-tails and differed only in the Siskiyou Mountains, where

CpDNA haplotype variation reveals strong human influence on oak stands of the Veluwe forest in the Netherlands

NARCIS (Netherlands)

Buiteveld, J.; Koelewijn, H.P.

2006-01-01

We examined chloroplast DNA (cpDNA) variation in 78 oak stands of an important forest complex (the Veluwe) in The Netherlands. Based on historical maps and information oak stands were classified as planted or autochthonous. A genetic study by means of cpDNA haplotype characterisation was carried out

Structura unor arborete exploatabile din regiunea de munte [Structure of some exploitable forest stands from the mountainous area

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Prodan M

2005-07-01

Full Text Available The paper presents one of the first scientific works of the prof. dr. dr. h. c. Michail Prodan, published in the Romanian forestry journal “Viaţa forestieră” (“The forestry life”, in 1940, before starting his prodigious career in Germany. The used data - as in some of his next papers - are from the forest inventories performed in the forest districts of the Romanian Orthodox Religion Found from Bucovina (Eastern Carpathians with the occasion of the forest management plans renewal. Some details: (natural, almost primeval forest stands between 100-200 years, pure or mixed from species Norway spruce, Silver fir, Beech, in total 200,000 records. The analyzed stands were grouped based on Feistmantel class fertility and the basic analysis were the distribution of tree diameters, for these tree species and fertility classes. were computed the theoretical distribution for the diameter classes, using the Charlier approach

Carbon and Nitrogen dynamics in forest soils depending on light conditions and tree species

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Veselinovic, Bojana; Hager, Herbert

2013-04-01

Climate change mitigation actions under the Kyoto Protocol apply among other decreases of CO2-emissions and/or increases of carbon (C) stocks. As soils represent the second biggest C-reservoir on Earth, an exact estimation of the stocks and reliable knowledge on C-dynamics in forest soils is of high importance. Anyhow, here, the accurate GHG-accounting, emission reductions and increase in C stocks is hampered due to lack of reliable data and solid statistical methods for the factors which influence C-sequestration in and its release from these systems. In spite of good progress in the scientific research, these factors are numerous and diverse in their interactions. This work focuses on influence of the economically relevant tree species - Picea abies, Fagus sylvatica and Quercus spp. - and light conditions on forest floor and mineral soil C and N dynamics in forest soils. Spruce monocultures have been widely used management practices in central European forests during the past century. Such stands are in lower altitudes and on heavy and water logged soils unstable and prone to disturbances, especially to windthrows. We hypothesize that windthrow areas loose C & N and that the establishment of the previous nutrient stocks is, if at all, only possible to be reached over the longer periods of time. We research also how the increased OM depletion affects the change of C & N stocks in forest floor vs. mineral soil. Conversion of such secondary spruce monocultures to site adequate beech and oak forests may enable higher stocks allocated predominantly as stable organic carbon and as plant available nitrogen. For this purpose sites at 300-700 m altitude with planosols were chosen in the region of the Northern Alpine Foothills. A false chronosequence approach was used in order to evaluate the impacts of the tree species and change in light conditions on dynamic of C & N in the forest floor and mineral soil, over the period 0-100 (for oak 120 y.) years. The C- and N

Ground beetle (Coleoptera, Carabidae) assemblages inhabiting Scots pine stands of Puszcza Piska Forest: six-year responses to a tornado impact.

Science.gov (United States)

Skłodowski, Jarosław; Garbalińska, Paulina

2011-01-01

Ground beetle assemblages were studied during 2003-08 in the Pisz Forest by comparing stands disturbed by a tornado to undisturbed control stands. The following exploratory questions were put forward. (1) How do the carabid assemblages change during six years following the tornado impact? (2) Does the carabid assemblage recovery begin during the six first post-tornado years? To assess the state of carabid assemblages we used two indices: the MIB (Mean Individual Biomass) and the SPC (Sum of Progressive Characteristics). Carabid assemblages in the disturbed and in the control stands, as expressed by these two indices, were compared using the length of a regression distance (sample distance in a MIB:SPC coordinate system). A cluster analysis revealed that the assemblages of the disturbed and the control stands were different. The tornado-impacted stands produced lower carabid catch rates, but species richness was significantly higher there than in the control stands. They hosted lower proportions of individuals of European species, of large zoophages, and of forest and brachypterous species, than the control stands. The observed reduction in SPC and MIB, and an increase in the regression distances may indicate that the carabid assemblages had not started to recover from the tornado-caused disturbance. Carabid assemblages apparently responded to the tornado in two steps. Firstly, the first three years were characterized by moderate decreases of index values. Secondly, from the fourth to the sixth year after the tornado, many observed changes became magnified. We did not observe clear signals of the recovery of forest carabid assemblages during the six follow-up years.

Forest Plant community changes during 1989-2007 in response to climate warming in the Jura Mountains (France and Switzerland)

DEFF Research Database (Denmark)

Lenoir, Jonathan; Gégout, J.C.; Dupouey, J.L.

2010-01-01

Question: How strong are climate warming-driven changes within mid-elevation forest communities? Observations of plant community change within temperate mountain forest ecosystems in response to recent warming are scarce in comparison to high-elevation alpine and nival ecosystems, perhaps...... reflecting the confounding influence of forest stand dynamics. Location: Jura Mountains (France and Switzerland). Methods: We assessed changes in plant community composition by surveying 154 Abies alba forest vegetation relevés (550-1,350 m a.s.l.) in 1989 and 2007. Over this period, temperatures increased...... while precipitation did not change. Correspondence analysis (CA) and ecological indicator values were used to measure changes in plant community composition. Relevés in even- and uneven-aged stands were analysed separately to determine the influence of forest stand dynamics. We also analysed changes...

Effect of long-term understory prescribed burning on standing and down dead woody material in dry upland oak forests

Science.gov (United States)

Polo, John A.; Hallgren, S.W.; Leslie,, David M.

2013-01-01

Dead woody material, long ignored or viewed as a nuisance for forest management, has gained appreciation for its many roles in the forest including wildlife habitat, nutrient storage and cycling, energy for trophic webs, protection of soil, fuel for fire and carbon storage. The growing interest in managing dead woody material has created strong demand for greater understanding of factors controlling amounts and turnover. Prescribed burning, an important management tool, may have strong effects of dead woody material given fire’s capacity to create and consume dead woody material. We determined effects of long-term understory prescribed burning on standing and down woody material in upland oak forests in south-central North America. We hypothesized that as frequency of fire increased in these stands the amount of deadwood would decrease and the fine woody material would decrease more rapidly than coarse woody material. The study was conducted in forests dominated by post oak (Quercus stellata) and blackjack oak (Quercus marilandica) in wildlife management areas where understory prescribed burning had been practiced for over 20 years and the range of burn frequencies was 0 (unburned) fires per decade (FPD) to 4.6 FPD. The amount of deadwood was low compared with more productive forests in southeastern North America. The biomass (24.7 Mg ha-1) and carbon stocks (11.7 Mg ha-1) were distributed among standing dead (22%), coarse woody debris (CWD, dia. > 7.5 cm., 12%), fine woody debris (FWD, dia. prescribed burning influenced the amount and size distribution of standing and down dead woody material. There were two explanations for the lack of a detectable effect. First, a high incidence of severe weather including ice storms and strong winds that produce large amounts of deadwood intermittently in an irregular pattern across the landscape may preclude detecting a strong effect of understory prescribed burning. Second, fire suppression during the first one-half of the

Compensating effect of sap velocity for stand density leads to uniform hillslope-scale forest transpiration across a steep valley cross-section

Science.gov (United States)

Renner, Maik; Hassler, Sibylle; Blume, Theresa; Weiler, Markus; Hildebrandt, Anke; Guderle, Marcus; Schymanski, Stan; Kleidon, Axel

2016-04-01

Roberts (1983) found that forest transpiration is relatively uniform across different climatic conditions and suggested that forest transpiration is a conservative process compensating for environmental heterogeneity. Here we test this hypothesis at a steep valley cross-section composed of European Beech in the Attert basin in Luxemburg. We use sapflow, soil moisture, biometric and meteorological data from 6 sites along a transect to estimate site scale transpiration rates. Despite opposing hillslope orientation, different slope angles and forest stand structures, we estimated relatively similar transpiration responses to atmospheric demand and seasonal transpiration totals. This similarity is related to a negative correlation between sap velocity and site-average sapwood area. At the south facing sites with an old, even-aged stand structure and closed canopy layer, we observe significantly lower sap velocities but similar stand-average transpiration rates compared to the north-facing sites with open canopy structure, tall dominant trees and dense understorey. This suggests that plant hydraulic co-ordination allows for flexible responses to environmental conditions leading to similar transpiration rates close to the water and energy limits despite the apparent heterogeneity in exposition, stand density and soil moisture. References Roberts, J. (1983). Forest transpiration: A conservative hydrological process? Journal of Hydrology 66, 133-141.

Fuel buildup and potential fire behavior after stand-replacing fires, logging fire-killed trees and herbicide shrub removal in Sierra Nevada forests

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McGinnis, Thomas W.; Keeley, Jon E.; Stephens, Scott L.; Roller, Gary B.

2010-01-01

Typically, after large stand-replacing fires in mid-elevation Sierra Nevada forests, dense shrub fields occupy sites formerly occupied by mature conifers, until eventually conifers overtop and shade out shrubs. Attempting to reduce fuel loads and expedite forest regeneration in these areas, the USDA Forest Service often disrupts this cycle by the logging of fire-killed trees, replanting of conifers and killing of shrubs. We measured the effects of these treatments on live and dead fuel loads and alien species and modeled potential fire behavior and fire effects on regenerating forests. Sampling occurred in untreated, logged and herbicide-treated stands throughout the Sierra Nevada in four large fire areas 4–21 years after stand-replacing fires. Logging fire-killed trees significantly increased total available dead fuel loads in the short term but did not affect shrub cover, grass and forb cover, alien species cover or alien species richness. Despite the greater available dead fuel loads, fire behavior was not modeled to be different between logged and untreated stands, due to abundant shrub fuels in both logged and untreated stands. In contrast, the herbicide treatment directed at shrubs resulted in extremely low shrub cover, significantly greater alien species richness and significantly greater alien grass and forb cover. Grass and forb cover was strongly correlated with solar radiation on the ground, which may be the primary reason that grass and forb cover was higher in herbicide treated stands with low shrub and tree cover. Repeat burning exacerbated the alien grass problem in some stands. Although modeled surface fire flame lengths and rates of spread were found to be greater in stands dominated by shrubs, compared to low shrub cover conifer plantations, surface fire would still be intense enough to kill most trees, given their small size and low crown heights in the first two decades after planting.

Post Wildfire Changes in Plant Functioning and Vegetation Dynamics: Implications for Water Fluxes in Re-sprouting Forests

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Nolan, R. H.; Lane, P. N.; Mitchell, P. J.; Bradstock, R. A.

2011-12-01

Fire induced changes to the vegetation dynamics in temperate forests have been demonstrated to affect evapotranspiration (Et) rates through increases in plant size and density and stand-level transpiration and interception. In many cases these transient changes in forest structure result in substantial declines in stream flow for protracted periods after the disturbance. However to date research has focused on the wetter 'ash' forests of south-eastern Australia which solely regenerate via seedlings, it is unknown what changes in Et may occur in those forests which re-sprout post-fire. We hypothesize that Et fluxes track post-fire changes in sapwood area and leaf area index (L) in re-sprouting temperate forests, increasing as the forest regenerates. Following the 2009 Black Saturday wildfires in Victoria, we monitored Et rates for over a year in both damp and dry re-sprouting forest, incorporating a range of fire severity classes. Components of Et including overstorey transpiration, rainfall interception loss and forest floor Et were measured in conjunction with changes in L, sapwood area and leaf physiology. The monitoring period began one year post-fire with a typical hot, dry summer, at which stage Et rates in burnt forest were similar or less than those in unburnt forest. During the following summer, which was one of the wettest on record, Et increased across all monitoring plots but particularly so in the burnt forest where seedling regeneration resulted in an understorey L nearly twice that of unburnt forest. Forest floor Et was up to 46% higher in burnt forest, and rainfall interception values accounted for approximately 25% of rainfall compared to 15% in unburnt forest. The greatest increase in canopy transpiration rates over this period occurred in those trees subject to a low intensity fire where most of the canopy remained intact but there was also fire-triggered sprouting of new leaves along the trunk and main branches. In these trees rates of sapflow

Real-time positioning in logging: Effects of forest stand characteristics, topography, and line-of-sight obstructions on GNSS-RF transponder accuracy and radio signal propagation.

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Eloise G Zimbelman

Full Text Available Real-time positioning on mobile devices using global navigation satellite system (GNSS technology paired with radio frequency (RF transmission (GNSS-RF may help to improve safety on logging operations by increasing situational awareness. However, GNSS positional accuracy for ground workers in motion may be reduced by multipath error, satellite signal obstruction, or other factors. Radio propagation of GNSS locations may also be impacted due to line-of-sight (LOS obstruction in remote, forested areas. The objective of this study was to characterize the effects of forest stand characteristics, topography, and other LOS obstructions on the GNSS accuracy and radio signal propagation quality of multiple Raveon Atlas PT GNSS-RF transponders functioning as a network in a range of forest conditions. Because most previous research with GNSS in forestry has focused on stationary units, we chose to analyze units in motion by evaluating the time-to-signal accuracy of geofence crossings in 21 randomly-selected stands on the University of Idaho Experimental Forest. Specifically, we studied the effects of forest stand characteristics, topography, and LOS obstructions on (1 the odds of missed GNSS-RF signals, (2 the root mean squared error (RMSE of Atlas PTs, and (3 the time-to-signal accuracy of safety geofence crossings in forested environments. Mixed-effects models used to analyze the data showed that stand characteristics, topography, and obstructions in the LOS affected the odds of missed radio signals while stand variables alone affected RMSE. Both stand characteristics and topography affected the accuracy of geofence alerts.

Real-time positioning in logging: Effects of forest stand characteristics, topography, and line-of-sight obstructions on GNSS-RF transponder accuracy and radio signal propagation.

Science.gov (United States)

Zimbelman, Eloise G; Keefe, Robert F

2018-01-01

Real-time positioning on mobile devices using global navigation satellite system (GNSS) technology paired with radio frequency (RF) transmission (GNSS-RF) may help to improve safety on logging operations by increasing situational awareness. However, GNSS positional accuracy for ground workers in motion may be reduced by multipath error, satellite signal obstruction, or other factors. Radio propagation of GNSS locations may also be impacted due to line-of-sight (LOS) obstruction in remote, forested areas. The objective of this study was to characterize the effects of forest stand characteristics, topography, and other LOS obstructions on the GNSS accuracy and radio signal propagation quality of multiple Raveon Atlas PT GNSS-RF transponders functioning as a network in a range of forest conditions. Because most previous research with GNSS in forestry has focused on stationary units, we chose to analyze units in motion by evaluating the time-to-signal accuracy of geofence crossings in 21 randomly-selected stands on the University of Idaho Experimental Forest. Specifically, we studied the effects of forest stand characteristics, topography, and LOS obstructions on (1) the odds of missed GNSS-RF signals, (2) the root mean squared error (RMSE) of Atlas PTs, and (3) the time-to-signal accuracy of safety geofence crossings in forested environments. Mixed-effects models used to analyze the data showed that stand characteristics, topography, and obstructions in the LOS affected the odds of missed radio signals while stand variables alone affected RMSE. Both stand characteristics and topography affected the accuracy of geofence alerts.

Statistical data on forest fund of Russia and changing of forest productivity in the second half of XX century

Science.gov (United States)

Alexeyev V.A.; Markov M.V.; R.A. Birdsey; Birdsey R.A.

2004-01-01

Contains statistical data on area and growing-stock volume of forest lands in Oblasts, Krays and Republics of Russian Federation, for the period 1961-1998. Positive dynamics of average growing stock for coniferous, deciduous hardwood and deciduous softwood tree stands by stand-age groups were disclosed. The impact of main anthropogenic and natural factors, including...

Influence of timber harvesting costs on the layout of cuttings and economic return in forest planning based on dynamic treatment units

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Adrián Pascual

2018-05-01

Full Text Available Aim of study: To analyze the influence of harvesting costs on the distribution and type of cuttings when forest management planning is based on the dynamic treatment units (DTUs approach. Area of study: A Mediterranean pine forest in Central Spain. Materials and methods: Airborne laser scanning data were used in area-based approach to predict stand attributes and delineate segments that were used as calculation units. Predicted stand attributes and existing models for diameter distribution and individual-tree growth were used to simulate alternative management schedules for each segment for a 60-year planning horizon divided into three 20-year periods. Three alternative forest planning problems were formulated. They aimed to maximize or minimize net income, or maximize timber production with a constant flow of harvested timber. Spatial goals were used in all cases to enhance the clustering of treatments. Main results: Maxizing timber production without considering harvesting costs can be costly, even close to the plan that minimized net incomes. Maximizing net incomes led to frequent use of final felling instead of thinnings, placing cuttings near forest roads and creating more compact DTUs than obtained in the plan that maximized timber production. Research highlights: Compared to previous studies on DTUs, this study integrated felling and forwarding costs, which depended on distance to road and stand attributes, in the process of creating DTUs by means of spatial optimization.

Forest Management and the Evolution of Project Design in Dynamic Wildland Urban Interface Fire Environments

Science.gov (United States)

Conway, S.

2014-12-01

The Truckee Ranger District on the Tahoe National Forest, in the heart of the Sierra Nevada Mountains, has a rich history of human activities. Native American influences, comstock-era logging, fire suppression, development, and recreation have all shaped the natural environment into what it is today. Like much of our national forests in California, forest conditions that have developed are generally much more homogenous and less resistant to disturbance from fire, insect, and disease than they might have been without the myriad of human influences. However, in order to improve the resiliency of our forests to stand replacing disturbances like high severity fire, while managing for integrated anthropomorphic values, it is imperative that management evolve to meet those dynamic needs. Recent advances in remote sensing and GIS allow land managers more access to forest information and can inform site specific prescriptions to change site specific undesirable conditions. It is ecologically and politically complex, yet our forests deserve that microscope. This particular presentation will focus on how the Truckee Ranger District began this process of incorporating several values, generated from stakeholder collaboration, into one project's goals and how those lessons learned informed their most recent project.

Fine root dynamics for forests on contrasting soils in the Colombian Amazon

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E. M. Jiménez

2009-12-01

Full Text Available It has been hypothesized that as soil fertility increases, the amount of carbon allocated to below-ground production (fine roots should decrease. To evaluate this hypothesis, we measured the standing crop fine root mass and the production of fine roots (<2 mm by two methods: (1 ingrowth cores and, (2 sequential soil coring, during 2.2 years in two lowland forests growing on different soils types in the Colombian Amazon. Differences of soil resources were defined by the type and physical and chemical properties of soil: a forest on clay loam soil (Endostagnic Plinthosol at the Amacayacu National Natural Park and, the other on white sand (Ortseinc Podzol at the Zafire Biological Station, located in the Forest Reservation of the Calderón River. We found that the standing crop fine root mass and the production was significantly different between soil depths (0–10 and 10–20 cm and also between forests. The loamy sand forest allocated more carbon to fine roots than the clay loam forest with the production in loamy sand forest twice (mean±standard error=2.98±0.36 and 3.33±0.69 Mg C ha⁻¹ yr⁻¹, method 1 and 2, respectively as much as for the more fertile loamy soil forest (1.51±0.14, method 1, and from 1.03±0.31 to 1.36±0.23 Mg C ha⁻¹ yr⁻¹, method 2. Similarly, the average of standing crop fine root mass was higher in the white-sands forest (10.94±0.33 Mg C ha⁻¹ as compared to the forest on the more fertile soil (from 3.04±0.15 to 3.64±0.18 Mg C ha⁻¹. The standing crop fine root mass also showed a temporal pattern related to rainfall, with the production of fine roots decreasing substantially in the dry period of the year 2005. These results suggest that soil resources may play an important role in patterns of carbon allocation to the production of fine roots in these forests as the proportion of carbon allocated to above- and below-ground organs is different

Modeling population dynamics and woody biomass of Alaska coastal forest

Science.gov (United States)

Randy L. Peterson; Jingjing Liang; Tara M. Barrett

2014-01-01

Alaska coastal forest, 6.2 million ha in size, has been managed in the past mainly through clearcutting. Declining harvest and dwindling commercial forest resources over the past 2 decades have led to increased interest in management of young-growth stands and utilization of woody biomass for bioenergy. However, existing models to support these new management systems...

Windthrow Dynamics in Boreal Ontario: A Simulation of the Vulnerability of Several Stand Types across a Range of Wind Speeds

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Kenneth A. Anyomi

2017-06-01

Full Text Available In Boreal North America, management approaches inspired by the variability in natural disturbances are expected to produce more resilient forests. Wind storms are recurrent within Boreal Ontario. The objective of this study was to simulate wind damage for common Boreal forest types for regular as well as extreme wind speeds. The ForestGALES_BC windthrow prediction model was used for these simulations. Input tree-level data were derived from permanent sample plot (PSP data provided by the Ontario Ministry of Natural Resources. PSPs were assigned to one of nine stand types: Balsam fir-, Jack pine-, Black spruce-, and hardwood-dominated stands, and, Jack pine-, spruce-, conifer-, hardwood-, and Red and White pine-mixed species stands. Morphological and biomechanical parameters for the major tree species were obtained from the literature. At 5 m/s, predicted windthrow ranged from 0 to 20%, with damage increasing to 2 to 90% for winds of 20 m/s and to 10 to 100% for winds of 40 m/s. Windthrow varied by forest stand type, with lower vulnerability within hardwoods. This is the first study to provide such broad simulations of windthrow vulnerability data for Boreal North America, and we believe this will benefit policy decisions regarding risk management and forest planning.

Trace gas emissions from a chronosequence of bark beetle-infested lodgepole pine (Pinus contorta) forest stands

Science.gov (United States)

Norton, U.; Pendall, E.; Ewers, B. E.; Borkhuu, B.

2011-12-01

Severe outbreak of mountain pine beetle (MPB) and associated blue stain fungi have killed millions of hectares of coniferous forests in Western North America. This unprecedented disturbance has critically impacted ecosystem biogeochemistry and net carbon (C) and nitrogen (N) fluxes. However, the effects on greenhouse gas (GHG) emissions and drivers of biogeochemical processes that trigger GHG emissions following MPB infestations are not well understood. Such information can help assess regional-level changes in ecosystem C and N budgets and large-scale disturbance impacts on gas exchange between the atmosphere and terrestrial ecosystem. The overall objective of this research was to assess the immediate responses of GHG fluxes and soil C and N mineralization rates along a chronosequence of recently infested (1-yr, 3-yr and 4-yr ago) and uninfested (150-yr, 20-yr and 15-yr old) lodgepole pine stands in Medicine Bow National Forest in southeastern Wyoming. We hypothesize that MPB-induced tree mortality significantly changes stand-level hydrology, soil organic matter quality and chemistry of aboveground and belowground plant inputs. Consequently, these modifications influence nitrous oxide (N2O) emissions and methane (CH4) assimilation. Biweekly GHG measurements using static chambers were carried out during three consecutive snow-free growing seasons. Our results suggest that a stand infested within a year already shows a 20% increase in spring N2O production and a small decline in summer CH4 assimilation when compared to uninfested stands. Stands infested three and four years prior to our measurements produce over three times more N2O and assimilate three to five times less CH4 when compared to uninfested stands. In addition, a notable increase in soil moisture content and soil mineral N concentrations following early onset of the MPB infestation was also observed. An overall increase in N2O production and decline in CH4 assimilation following MPB infestation may

Dynamics of radionuclides in forest ecosystems

International Nuclear Information System (INIS)

Steiner, M.

2004-01-01

The unique physiology and the layered structure of forest ecosystems result in dynamic transport and transfer processes which greatly differ from those in agricultural ecosystems. Radionuclides are retained in the upper organic horizons of forest soil for several decades and remain highly available for uptake by fungi and green plants. Contamination levels of mushrooms and game may therefore by far exceed those of agricultural produce. The efficient cycling of nutrients and radionuclides, which is characteristic for ecosystems poor in nutrients, can largely be attributed to forest soil with its complex and multi-layered structure and fungal activity. Fungi directly affect dynamic processes, playing a key role in the mobilization, uptake and translocation of nutrients and radionuclides. Fungal fruit bodies may be highly contaminated foodstuff and fodder. They are most likely the cause of the surprising trend of increasing contamination of wild boar which has been observed in the last few years in Germany. This paper is intended to give a qualitative survey of dynamic transport processes in forests and their relevance for radiation exposure to man. (orig.)

Successional dynamics drive tropical forest nutrient limitation

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Chou, C.; Hedin, L. O. O.

2017-12-01

It is increasingly recognized that nutrients such as N and P may significantly constrain the land carbon sink. However, we currently lack a complete understanding of these nutrient cycles in forest ecosystems and how to incorporate them into Earth System Models. We have developed a framework of dynamic forest nutrient limitation, focusing on the role of secondary forest succession and canopy gap disturbances as bottlenecks of high plant nutrient demand and limitation. We used succession biomass data to parameterize a simple ecosystem model and examined the dynamics of nutrient limitation throughout tropical secondary forest succession. Due to the patterns of biomass recovery in secondary tropical forests, we found high nutrient demand from rapid biomass accumulation in the earliest years of succession. Depending on previous land use scenarios, soil nutrient availability may also be low in this time period. Coupled together, this is evidence that there may be high biomass nutrient limitation early in succession, which is partially met by abundant symbiotic nitrogen fixation from certain tree species. We predict a switch from nitrogen limitation in early succession to one of three conditions: (i) phosphorus only, (ii) phosphorus plus nitrogen, or (iii) phosphorus, nitrogen, plus light co-limitation. We will discuss the mechanisms that govern the exact trajectory of limitation as forests build biomass. In addition, we used our model to explore scenarios of tropical secondary forest impermanence and the impacts of these dynamics on ecosystem nutrient limitation. We found that secondary forest impermanence exacerbates nutrient limitation and the need for nitrogen fixation early in succession. Together, these results indicate that biomass recovery dynamics early in succession as well as their connection to nutrient demand and limitation are fundamental for understanding and modeling nutrient limitation of the tropical forest carbon sink.

[Impacts of forest and precipitation on runoff and sediment in Tianshui watershed and GM models].

Science.gov (United States)

Ouyang, H

2000-12-01

This paper analyzed the impacts of foret stand volume and precipitation on annual erosion modulus, mean sediment, maximum sediment, mean runoff, maximum runoff, minimum runoff, mean water level, maximum water level and minimum water level in Tianshui watershed, and also analyzed the effect of the variation of forest stand volume on monthly mean runoff, minimum runoff and mean water level. The dynamic models of grey system GM(1, N) were constructed to simulate the changes of these hydrological elements. The dynamic GM models on the impact of stand volumes of different forest types(Chinese fir, masson pine and broad-leaved forests) with different age classes(young, middle-aged, mature and over-mature) and that of precipitation on the hydrological elements were also constructed, and their changes with time were analyzed.

Features of secondary birch young stands in low mountain Pokuttya (Ukrainian Carpathian mts.

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S. Y. Milevskaya

2015-06-01

Full Text Available Forest landscapes of the region during the last 3–5 centuries undergone the profound anthropogenic transformation. Secondary young stands occupy 25% of the total forest area. The problem of derivatives is particularly relevant for the modern forest typology in the Carpathian region. It requires the reflection in its dynamic trends shaping the stands, especially mixed young stands. The aim of our study consisted in getting the knowledge of the structural features of the secondary phytocoenosis of birch young stands in this area.The object of the study was age class I saplings growing in the mountainous part of Pokuttya, particularly in the basin of the Lutshka River. The conceptual basis of our study is the modern dynamic vision that every forest type is a consecutive series of forest plant communities within each type of homogeneous growing conditions. We apply methods of ecological-floristic research of the Brown-Blanke school in the interpretation of the Polish school phytosociology. However we also take into account both syntaxonomy generalizations of the Ukrainian scientists. The actual material comprises the original geobotanical studies with fixation of the vast majority of species in plant communities. Mainly the species having diagnostic value to separate syntaxons were taken into account in the analytical processing. Young forest stands (with the height of 8–12 m and crown cover of 70% together form the trees Betula pendula and B. pubescens. Fairly numerous admixture is formed by trees Alnus incana; besides, there are Fagus sylvatica, Populus tremula, Quercus robur, Padus avium. For dominants, they can be called “grey-alder birch blackberry sedge bracken fern” – Betula pendula+Alnus incana–Rubus caesius–Carex brizoides+Pteridium aquilinum. It is rich in floristic composition of the plant communities. They contain at least 12 species of trees, 3 species of shrubs, 4 species of bushes and 89 species of herbs. Diagnostic

Acute effects of rearfoot manipulation on dynamic standing balance in healthy individuals.

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Wassinger, Craig A; Rockett, Ariel; Pitman, Lucas; Murphy, Matthew Matt; Peters, Charles

2014-06-01

Dynamic standing balance is essential to perform functional activities and is included in the treatment of many lower extremity injuries. Physiotherapists utilize many methods to restore standing balance including stability exercises, functional retraining, and manual therapy. The purpose of this study was to investigate the effects of a rearfoot distraction manipulation on dynamic standing balance. Twenty healthy participants (age: 24.4 ± 2.8 years; height: 162.9 ± 37.7 cm; mass: 68.0 ± 4.8 kg; right leg dominant = 20) completed this study. Following familiarization, dynamic standing balance was assessed during: (1) an experimental condition immediately following a rearfoot distraction manipulation, and (2) a control condition. Dominant leg balance was quantified using the Y-balance test which measures lower extremity reach distances. Reach distances were normalized to leg length and measured in the anterior, posteromedial and posterolateral directions. Overall balance was calculated through the summing of all normalized directions. Paired t-tests and Wilcoxon rank tests were used to compare balance scores for parametric and non-parametric data as appropriate. Significance was set at 0.05 a priori. Effect size (ES) was calculated to determine the clinical impact of the manipulation. Increased reach distances (indicating improved balance) were noted following manipulation for overall balance (p = 0.03, ES = 0.26) and in the posteromedial direction (p = 0.01, ES = 0.42). Reach distances did not differ for the anterior (p = 0.11, ES = 0.16) or posterolateral (p = 0.11, ES = 0.25) components. Dynamic standing balance improved after a rearfoot distraction manipulation in healthy participants. It is hypothesized that manual therapy applied to the foot and ankle may be beneficial to augment other therapeutic modalities when working with patients to improve dynamic standing balance. Copyright © 2013 Elsevier Ltd. All rights reserved.

Transporting dynamics of radioactive cesium in a forest ecosystem and its discharge processes

Energy Technology Data Exchange (ETDEWEB)

Iseda, Kohei; Ohte, Nobuhito; Tanoi, Keitaro; Endo, Izuki; Oda, Tomoki; Kato, Hiroyu [Graduate School of Agricultural and Life Sciences, University of Tokyo (Japan)

2014-07-01

A lot of radioactive substance including {sup 137}Cs, {sup 134}Cs fell out to Tohoku and Kanto region in particular Fukushima prefecture after the accident of Fukushima-daiichi nuclear power plant. Generally, cesium tends to attach to clay particle and organic matter. These clay particle and organic matter can potentially flow out from the forest through the river to the downstream not only as particulate matter but also dissolved matter. It is likely that behavior of cesium is similar to sediment locomotion. The objective of this study is to understand transporting dynamics of radioactive cesium inside and outside of the forest. We started investigations on transporting dynamics of cesium in the forest upper stream of Kami-Oguni river in Date city Fukushima prefecture located in about 50 km from the nuclear power plant since July 2012. We conducted river water sampling at 9 points along the river from the uppermost stream to the middle reaches during low flow condition once a month. We also sampled river water during storm event for 5 times in order to capture the change of {sup 137}Cs concentration in a flood stage. Samples were filtered and separated into particulate and dissolved matters using glass micro-fiber filters (GF/F). Samples were analyzed their {sup 137}Cs concentration by Germanium semiconductor detector at University of Tokyo. During low flow condition, {sup 137}Cs was detected only a very small amount both in particulate and dissolved matters. In contrast, during high flow condition, {sup 137}Cs was detected about 10-100 times higher than that of during low flow condition in particulate matter. We estimated discharge flux of {sup 137}Cs from the forest using the relations between water discharge and {sup 137}Cs concentration. It was 0.977 Bq/(m2 day ) (2012/8/31-2013/4/19). In the forest, we set 2 deciduous tree plots (Quercus serrata, Zelkova serrata and so on) and 1 evergreen confer plot (Cyptomeria japonica). Atmospheric depositions of {sup 137

Using a standing-tree acoustic tool to identify forest stands for the production of mechanically-graded lumber.

Science.gov (United States)

Paradis, Normand; Auty, David; Carter, Peter; Achim, Alexis

2013-03-12

This study investigates how the use of a Hitman ST300 acoustic sensor can help identify the best forest stands to be used as supply sources for the production of Machine Stress-Rated (MSR) lumber. Using two piezoelectric sensors, the ST300 measures the velocity of a mechanical wave induced in a standing tree. Measurements were made on 333 black spruce (Picea mariana (Mill.) BSP) trees from the North Shore region, Quebec (Canada) selected across a range of locations and along a chronosequence of elapsed time since the last fire (TSF). Logs were cut from a subsample of 39 trees, and sawn into 77 pieces of 38 mm × 89 mm cross-section before undergoing mechanical testing according to ASTM standard D-4761. A linear regression model was developed to predict the static modulus of elasticity of lumber using tree acoustic velocity and stem diameter at 1.3 m above ground level (R2 = 0.41). Results suggest that, at a regional level, 92% of the black spruce trees meet the requirements of MSR grade 1650Fb-1.5E, whilst 64% and 34% meet the 2100Fb-1.8E and 2400Fb-2.0E, respectively. Mature stands with a TSF < 150 years had 11 and 18% more boards in the latter two categories, respectively, and therefore represented the best supply source for MSR lumber.

[Wood transformation in dead-standing trees in the forest-tundra of Central Siberia].

Science.gov (United States)

Mukhortova, L V; Kirdianov, A V; Myglan, V S; Guggenberger, G

2009-01-01

Changes in the composition of wood organic matter in dead-standing spruce and larch trees depending on the period after their death have been studied in the north of Central Siberia. The period after tree death has been estimated by means of cross-dating. The results show that changes in the composition of wood organic matter in 63% of cases are contingent on tree species. Wood decomposition in dead-standing trees is accompanied by an increase in the contents of alkali-soluble organic compounds. Lignin oxidation in larch begins approximately 80 years after tree death, whereas its transformation in spruce begins not earlier than after 100 years. In the forest-tundra of Central Siberia, the rate of wood organic matter transformation in dead-standing trees is one to two orders of magnitude lower than in fallen wood, which accounts for their role as a long-term store of carbon and mineral elements in these ecosystems.

Investigations into the fungal flora of forest stands under severe stress from immissions

International Nuclear Information System (INIS)

Butin, H.

1992-01-01

This finalized research project on the fungal flora of forest stands under severe stress form immissions looked into the question of the contribution of fungi to the triggering of topical forest damage and investigated whether correlations between certain symptoms and needle yellowing or root damage can be established. The main tree species selected were spruce and pine; but spot sample checks were also carried out on other tree species. Fungal flora was determined both qualitatively and quantitatively, and the pathogenic significance of the individual species was determined. Further, it was investigated whether fungal species are correlated to certain symptoms of damage, and which fungal species are. For selected fungal species, their pathogenicity was investigated by infection experiments. (RHE) [de

RGB-NDVI colour composites for visualizing forest change dynamics

Science.gov (United States)

Sader, S. A.; Winne, J. C.

1992-01-01

The study presents a simple and logical technique to display and quantify forest change using three dates of satellite imagery. The normalized difference vegetation index (NDVI) was computed for each date of imagery to define high and low vegetation biomass. Color composites were generated by combining each date of NDVI with either the red, green, or blue (RGB) image planes in an image display monitor. Harvest and regeneration areas were quantified by applying a modified parallelepiped classification creating an RGB-NDVI image with 27 classes that were grouped into nine major forest change categories. Aerial photographs and stand history maps are compared with the forest changes indicated by the RGB-NDVI image. The utility of the RGB-NDVI technique for supporting forest inventories and updating forest resource information systems are presented and discussed.

Post-fire diversity and abundance in pine and eucalipt stands in Portugal: effects of biogeography, topography, forest type and post-fire management

OpenAIRE

Maia, P.; Keizer, J.; Vasques, A.; Abrantes, N.; Roxo, L.; Fernandes, P.; Ferreira, A.; Moreira, F.

2014-01-01

This study concerned the mid-term regeneration of the woody understory vegetation of pure and mixed stands of Pinus pinaster Ait. and Eucalyptus globulus Labill. in northern and central Portugal following wildfires in 2005 and 2006. Pine and eucalypt stands are the most widespread and most fire-prone forest types in Portugal. The main aim was to investigate the importance of biogeography, topography, forest type and post-fire management operations in explaining the patterns in shr...

Standing crop and aboveground biomass partitioning of a dwarf mangrove forest in Taylor River Slough, Florida

Science.gov (United States)

Coronado-Molina, C.; Day, J.W.; Reyes, E.; Perez, B.C.

2004-01-01

The structure and standing crop biomass of a dwarf mangrove forest, located in the salinity transition zone ofTaylor River Slough in the Everglades National Park, were studied. Although the four mangrove species reported for Florida occurred at the study site, dwarf Rhizophora mangle trees dominated the forest. The structural characteristics of the mangrove forest were relatively simple: tree height varied from 0.9 to 1.2 meters, and tree density ranged from 7062 to 23 778 stems haa??1. An allometric relationship was developed to estimate leaf, branch, prop root, and total aboveground biomass of dwarf Rhizophora mangle trees. Total aboveground biomass and their components were best estimated as a power function of the crown area times number of prop roots as an independent variable (Y = B ?? Xa??0.5083). The allometric equation for each tree component was highly significant (pRhizophora mangle contributed 85% of total standing crop biomass. Conocarpus erectus, Laguncularia racemosa, and Avicennia germinans contributed the remaining biomass. Average aboveground biomass allocation was 69% for prop roots, 25% for stem and branches, and 6% for leaves. This aboveground biomass partitioning pattern, which gives a major role to prop roots that have the potential to produce an extensive root system, may be an important biological strategy in response to low phosphorus availability and relatively reduced soils that characterize mangrove forests in South Florida.

Overland flow generation processes in sub-humid Mediterranean forest stands

Science.gov (United States)

Ferreira, A. J. D.; Ferreira, C. S. S.; Coelho, C. O. A.; Walsh, R. P. D.; Shakesby, R. A.

2012-04-01

Forest soils in north and central Portugal have suffered and continue to suffer major structural changes as a result of forest management techniques, such as clear-felling and as a result of wildfire and rip-ploughing, which is carried out to prepare the ground for planting tree seedlings. In soils that have undergone these changes, the characteristics tend to be different for coniferous plantations, where the root system tends to die when the trees are cut following fire and subsequently may be consumed by fire to form a macropore network, and other types of tree plantations where the root system remains alive and allows regrowth from the sawn tree stumps. Overland flow thresholds decrease sharply as a result of rip-ploughing and forest fires and increase following clear-felling. The time taken for trees to reach maturity after wildfire differs markedly betwen the two main species (Pinus pinaster Aiton and Eucalyptus globulus Labill.) stands. In this paper, overland flow is considered in relation to rainfall, throughfall and throughflow, both in terms of hydrology and hydrochemistry in an attempt to understand overland flow generation mechanisms for a variety of forest land uses (mature pine and eucalyptus, pine seedling regrowth and eucalyptus regrowth from tree stumps, eucalyptus plantations and burned pine). Overland flow generation processes change sharply, even within a single rainfall event, as reflected in the soil hydrological processes and the hydrochemical fingerprints. These effects result from the different contact times for water and soil, which cause differences in the absorption and exhudation processes for the two species

Structural Dynamics of Tropical Moist Forest Gaps

Science.gov (United States)

Hunter, Maria O.; Keller, Michael; Morton, Douglas; Cook, Bruce; Lefsky, Michael; Ducey, Mark; Saleska, Scott; de Oliveira, Raimundo Cosme; Schietti, Juliana

2015-01-01

Gap phase dynamics are the dominant mode of forest turnover in tropical forests. However, gap processes are infrequently studied at the landscape scale. Airborne lidar data offer detailed information on three-dimensional forest structure, providing a means to characterize fine-scale (1 m) processes in tropical forests over large areas. Lidar-based estimates of forest structure (top down) differ from traditional field measurements (bottom up), and necessitate clear-cut definitions unencumbered by the wisdom of a field observer. We offer a new definition of a forest gap that is driven by forest dynamics and consistent with precise ranging measurements from airborne lidar data and tall, multi-layered tropical forest structure. We used 1000 ha of multi-temporal lidar data (2008, 2012) at two sites, the Tapajos National Forest and Ducke Reserve, to study gap dynamics in the Brazilian Amazon. Here, we identified dynamic gaps as contiguous areas of significant growth, that correspond to areas > 10 m2, with height gap at Tapajos National Forest (4.8 %) as compared to Ducke Reserve (2.0 %). On average, gaps were smaller at Ducke Reserve and closed slightly more rapidly, with estimated height gains of 1.2 m y-1 versus 1.1 m y-1 at Tapajos. At the Tapajos site, height growth in gap centers was greater than the average height gain in gaps (1.3 m y-1 versus 1.1 m y-1). Rates of height growth between lidar acquisitions reflect the interplay between gap edge mortality, horizontal ingrowth and gap size at the two sites. We estimated that approximately 10 % of gap area closed via horizontal ingrowth at Ducke Reserve as opposed to 6 % at Tapajos National Forest. Height loss (interpreted as repeat damage and/or mortality) and horizontal ingrowth accounted for similar proportions of gap area at Ducke Reserve (13 % and 10 %, respectively). At Tapajos, height loss had a much stronger signal (23 % versus 6 %) within gaps. Both sites demonstrate limited gap contagiousness defined by an

Developments to the Sylvan stand structure model to describe wood quality changes in southern bottomland hardwood forests because of forest management

Science.gov (United States)

Ian R. Scott

2009-01-01

Growth models can produce a wealth of detailed information that is often very difficult to perceive because it is frequently presented either as summary tables, stand view or landscape view visualizations. We have developed new tools for use with the Sylvan model (Larsen 1994) that allow the analysis of wood-quality changes as a consequence of forest management....

Spatial simulation of forest succession and timber harvesting using LANDIS

Science.gov (United States)

Eric J. Gustafson; Stephen R. Shifley; David J. Mladenoff; Kevin K. Nimerfro; Hong S. He

2000-01-01

The LANDIS model simulates ecological dynamics, including forest succession, disturbance, seed dispersal and establishment, fire and wind disturbance, and their interactions. We describe the addition to LANDIS of capabilities to simulate forest vegetation management, including harvest. Stands (groups of cells) are prioritized for harvest using one of four ranking...

Detection of Spatio-Temporal Changes of Norway Spruce Forest Stands in Ore Mountains Using Landsat Time Series and Airborne Hyperspectral Imagery

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Jan Mišurec

2016-01-01

Full Text Available The study focuses on spatio-temporal changes in the physiological status of the Norway spruce forests located at the central and western parts of the Ore Mountains (northwestern part of the Czech Republic, which suffered from severe environmental pollution from the 1970s to the 1990s. The situation started improving after the pollution loads decreased significantly at the end of the 1990s. The general trends in forest recovery were studied using the tasseled cap transformation and disturbance index (DI extracted from the 1985–2015 time series of Landsat data. In addition, 16 vegetation indices (VIs extracted from airborne hyperspectral (HS data acquired in 1998 using the Advanced Solid-State Array Spectroradiometer (ASAS and in 2013 using the Airborne Prism Experiment (APEX were used to study changes in forest health. The forest health status analysis of HS image data was performed at two levels of spatial resolution; at a tree level (original 2.0 m spatial resolution, as well as at a forest stand level (generalized to 6.0 m spatial resolution. The temporal changes were studied primarily using the VOG1 vegetation index (VI as it was showing high and stable sensitivity to forest damage for both spatial resolutions considered. In 1998, significant differences between the moderately to heavily damaged (central Ore Mountains and initially damaged (western Ore Mountains stands were detected for all the VIs tested. In 2013, the stands in the central Ore Mountains exhibited VI values much closer to the global mean, indicating an improvement in their health status. This result fully confirms the finding of the Landsat time series analysis. The greatest difference in Disturbance Index (DI values between the central (1998: 0.37 and western Ore Mountains stands (1998: −1.21 could be seen at the end of the 1990s. Nonetheless, levelling of the physiological status of Norway spruce was observed for the central and western parts of the Ore Mountains in

Monitoring U.S. forest dynamics with Landsat [Chapter 12

Science.gov (United States)

Jeffrey G. Masek; Sean P. Healey

2012-01-01

Forest dynamics in the United States differ substantially from those in the developing world and thus present unique monitoring requirements. While deforestation and conversion to semipermanent agriculture dominate tropical forest dynamics, the area of forest land in the United States has remained fairly constant for the last 50-60 years (Birdsey and Lewis 2003)....

Conversion from forests to pastures in the Colombian Amazon leads to differences in dead wood dynamics depending on land management practices.

Science.gov (United States)

Navarrete, Diego; Sitch, Stephen; Aragão, Luiz E O C; Pedroni, Lucio; Duque, Alvaro

2016-04-15

Dead wood, composed of coarse standing and fallen woody debris (CWD), is an important carbon (C) pool in tropical forests and its accounting is needed to reduce uncertainties within the strategies to mitigate climate change by reducing deforestation and forest degradation (REDD+). To date, information on CWD stocks in tropical forests is scarce and effects of land-cover conversion and land management practices on CWD dynamics remain largely unexplored. Here we present estimates on CWD stocks in primary forests in the Colombian Amazon and their dynamics along 20 years of forest-to-pasture conversion in two sub-regions with different management practices during pasture establishment: high-grazing intensity (HG) and low-grazing intensity (LG) sub-regions. Two 20-year-old chronosequences describing the forest-to-pasture conversion were identified in both sub-regions. The line-intersect and the plot-based methods were used to estimate fallen and standing CWD stocks, respectively. Total necromass in primary forests was similar between both sub-regions (35.6 ± 5.8 Mg ha(-1) in HG and 37.0 ± 7.4 Mg ha(-1) in LG). An increase of ∼124% in CWD stocks followed by a reduction to values close to those at the intact forests were registered after slash-and-burn practice was implemented in both sub-regions during the first two years of forest-to-pasture conversion. Implementation of machinery after using fire in HG pastures led to a reduction of 82% in CWD stocks during the second and fifth years of pasture establishment, compared to a decrease of 41% during the same period in LG where mechanization is not implemented. Finally, average necromass 20 years after forest-to-pasture conversion decreased to 3.5 ± 1.4 Mg ha(-1) in HG and 9.3 ± 3.5 Mg ha(-1) in LG, representing a total reduction of between 90% and 75% in each sub-region, respectively. These results highlight the importance of low-grazing intensity management practices during ranching activities in the Colombian

Nitrogen dynamics in oak forest soils along a historical deposition gradient

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Ralph E. J. Boerner; Elaine Kennedy Sutherland

1995-01-01

This study quantified soil nutrient status and N mineralization/nitrification potentials in soils of oakdominated, unmanaged forest stands in seven experimental forests ranging along a historical and current acidic deposition gradient from southern Illinois to central West Virginia, U.S.A. Among these seven sites (that spanned 8.5º of longitude) soil pH and Ca...

Using Lidar and color infrared imagery to successfully measure stand characteristics on the William B. Bankhead National Forest, Alabama

Science.gov (United States)

Jeffrey Stephens; Luben Dimov; Callie Schweitzer; Wubishet Tadesse

2008-01-01

Light detection and ranging (Lidar) and color infrared imagery (CIR) were used to quantify forest structure and to distinguish deciduous from coniferous trees for selected stands on the William B. Bankhead National Forest in Alabama. Lidar bare ground and vegetation point clouds were used to determine tree heights and tree locations. Lidar accuracy was assessed by...

Dynamic growth and yield model for Black pine stands in Spain

Energy Technology Data Exchange (ETDEWEB)

Mora, J. V.; Rio, M. del; Bravo-Oviedo, A.

2012-07-01

In a forestry context, modelling stand development over time relies on estimates of different stand characteristics obtained from equations which usually constitute a multivariate system. In this study we have developed a stand growth model for even-aged stands of Black pine (Pinus nigra Arn.) in Spain. The 53 plots used to fit the equations came from the permanent sample plot network established by the Forest Research Centre (INIA) in 1963 and 1964 in the main distribution regions of Black pine. The model is made up of a system of equations to predict growth and yield in volume and basal area. In the fitting phase we took into account the correlation between the measurements within the same plot and the cross-equation residual correlations. The model incorporates a control function to estimate the thinning effect and a function for predicting the reduction in tree number due to regular mortality. In addition, we use the three parameter Weibull distribution function to estimate the number of trees in each diameter class by recovering the parameters using the moment method. The developed model is useful for simulating the evolution of even-aged stands with and without thinnings and allows the estimation of number of trees by diameter classes. (Author) 44 refs.

The zero inflation of standing dead tree carbon stocks

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Christopher W. Woodall; David W. MacFarlane

2012-01-01

Given the importance of standing dead trees in numerous forest ecosystem attributes/processes such as carbon (C) stocks, the USDA Forest Service’s Forest Inventory and Analysis (FIA) program began consistent nationwide sampling of standing dead trees in 1999. Modeled estimates of standing dead tree C stocks are currently used as the official C stock estimates for the...

Severity of a mountain pine beetle outbreak across a range of stand conditions in Fraser Experimental Forest, Colorado, United States

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Anthony G. Vorster; Paul H. Evangelista; Thomas J. Stohlgren; Sunil Kumar; Charles C. Rhoades; Robert M. Hubbard; Antony S. Cheng; Kelly Elder

2017-01-01

The recent mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreaks had unprecedented effects on lodgepole pine (Pinus contorta var. latifolia) in western North America. We used data from 165 forest inventory plots to analyze stand conditions that regulate lodgepole pine mortality across a wide range of stand structure and species composition at the Fraser...

Fungal diseases of tree stands under urbanized conditions of Moscow

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Smirnova Oksana G.

2013-01-01

Full Text Available Phytosanitary and ecological estimation of tree-stands has been con­ducted at the Forest Experimental Station of Moscow Agricultural Academy and parks of Northeast of Moscow in 2007-2011. Fomes fomentarius was proved to be a very serious pathogen of trees under conditions of Moscow, Piptoporus betulinus, Phellinus igniarius, and Fomitopsis pinicola also occurred and caused damage to trees. This rather bad phytosanitary situation depends on alarming ecological situation in Moscow. At the Forest Experimental Station of Moscow Agricultural Academy a number and cover of lichens decreased. In general, all trees in Moscow are in dynamic equilibrium with the urbanized environment. In connection with this, the following classification of tree-stands was proposed for the urbanized environment: 1 - healthy trees, 2 - affected trees which can be managed, 3 - dry woods, 3a - very diseased. Many tree-stands in investigated regions of Moscow are found to belong to the groups 2 and 3c. All tree-stands must be carefully monitored and managed in order to provide a well-timed decision on the support system for preservation of trees as ‘lungs of city’ and avoid unpredictable tree falling which put people and traffic at risk.

Dynamic conservation of forest genetic resources in 33 European countries

NARCIS (Netherlands)

Lefevre, F.; Koskela, J.; Hubert, J.; Kraigher, H.; Longauer, R.; Olrik, D.C.; Vries, de S.M.G.

2013-01-01

Dynamic conservation of forest genetic resources (FGR) means maintaining the genetic diversity of trees within an evolutionary process and allowing generation turnover in the forest. We assessed the network of forests areas managed for the dynamic conservation of FGR (conservation units) across

Demographic disequilibrium caused by canopy gap expansion and recruitment failure triggers forest cover loss

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Martin Barrette; Louis Bélanger; Louis De Grandpré; Alejandro A. Royo

2017-01-01

In the absence of large-scale stand replacing disturbances, boreal forests can remain in the old-growth stage over time because of a dynamic equilibrium between small-scale mortality and regeneration processes. Although this gap paradigm has been a cornerstone of forest dynamics theory and practice for decades, evidence suggests that it could be disrupted, threatening...

Changes in standing stocks and fluxes of carbon due to salinization: tidal freshwater wetland forest retreat to marsh

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Krauss, K.; Noe, G. B.; Duberstein, J. A.; Conner, W. H.; Stagg, C. L.; Jones, M.; Bernhardt, C. E.; Cormier, N.

2017-12-01

Assessments of organic carbon (C) standing stocks and fluxes as wetland ecosystems transition from tidally influenced freshwater forested wetlands to low-salinity marshes are not typically included in "blue carbon" accounting. However, these ecosystems have the potential to store and convey large quantities of C. Here, we report on data collected from eight riverine sites along salinity and hydro-edaphic gradients in South Carolina and Georgia to provide the first complete estimates of C storage, flux, and burial, including estimation of C export to aquatic environments, in tidal freshwater forested wetlands undergoing transition to oligohaline marsh. Total standing stocks of C ranged from 280 to 891 Mg C/ha along both rivers but with no consistent trend in standing stock shifts along salinity gradients between the two rivers. Soil C standing stocks were most variable among sites. Furthermore, we assessed input (litterfall, woody growth, herbaceous growth, root growth and surface sediment C accretion) in comparison with output (surface litter decomposition, root decomposition and gaseous C) fluxes over periods ranging from 2 to 11 years. C sequestration from mass balance calculations ranged from 103 to 728 g C/m2/year among sites, with generally greater C sequestration on sites with prominent salinity-mediated conversion to oligohaline marsh. Dissolved C export was estimated as the difference between C sequestration and soil C burial using 14C dating of cores, and ranged from 144 to 404 g C/m2/year, representing a large amount of C export to feed aquatic biogeochemical transformations and secondary productivity. Along with C accounting, these sites also differed in how N and P were mineralized in soils, with considerable N mineralization on salinity-stressed (2.4-4.3 parts per thousand) forested sites with newly encroached marsh plants and considerable P mineralization on slightly higher salinity marshes. In all, C storage from tidal freshwater forested wetlands

Clustering Timber Harvests and the Effects of Dynamic Forest Management Policy on Forest Fragmentation

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Eric J. Gustafson

1998-01-01

To integrate multiple uses (mature forest and commodity production) better on forested lands, timber management strategies that cluster harvests have been proposed. One such approach clusters harvest activity in space and time, and rotates timber production zones across the landscape with a long temporal period (dynamic zoning). Dynamic zoning has...

The importance of biomass net uptake for a trace metal budget in a forest stand in north-eastern France

International Nuclear Information System (INIS)

Gandois, L.; Nicolas, M.; VanderHeijden, G.; Probst, A.

2010-01-01

The trace metal (TM: Cd, Cu, Ni, Pb and Zn) budget (stocks and annual fluxes) was evaluated in a forest stand (silver fir, Abies alba Miller) in north-eastern France. Trace metal concentrations were measured in different tree compartments in order to assess TM partitioning and dynamics in the trees. Inputs included bulk deposition, estimated dry deposition and weathering. Outputs were leaching and biomass exportation. Atmospheric deposition was the main input flux. The estimated dry deposition accounted for about 40% of the total trace metal deposition. The relative importance of leaching (estimated by a lumped parameter water balance model, BILJOU) and net biomass uptake (harvesting) for ecosystem exportation depended on the element. Trace metal distribution between tree compartments (stem wood and bark, branches and needles) indicated that Pb was mainly stored in the stem, whereas Zn and Ni, and to a lesser extent Cd and Cu, were translocated to aerial parts of the trees and cycled in the ecosystem. For Zn and Ni, leaching was the main output flux (> 95% of the total output) and the plot budget (input-output) was negative, whereas for Pb the biomass net exportation represented 60% of the outputs and the budget was balanced. Cadmium and Cu had intermediate behaviours, with 18% and 30% of the total output relative to biomass exportation, respectively, and the budgets were negative. The net uptake by biomass was particularly important for Pb budgets, less so for Cd and Cu and not very important for Zn and Ni in such forest stands.

The importance of biomass net uptake for a trace metal budget in a forest stand in north-eastern France.

Science.gov (United States)

Gandois, L; Nicolas, M; VanderHeijden, G; Probst, A

2010-11-01

The trace metal (TM: Cd, Cu, Ni, Pb and Zn) budget (stocks and annual fluxes) was evaluated in a forest stand (silver fir, Abies alba Miller) in north-eastern France. Trace metal concentrations were measured in different tree compartments in order to assess TM partitioning and dynamics in the trees. Inputs included bulk deposition, estimated dry deposition and weathering. Outputs were leaching and biomass exportation. Atmospheric deposition was the main input flux. The estimated dry deposition accounted for about 40% of the total trace metal deposition. The relative importance of leaching (estimated by a lumped parameter water balance model, BILJOU) and net biomass uptake (harvesting) for ecosystem exportation depended on the element. Trace metal distribution between tree compartments (stem wood and bark, branches and needles) indicated that Pb was mainly stored in the stem, whereas Zn and Ni, and to a lesser extent Cd and Cu, were translocated to aerial parts of the trees and cycled in the ecosystem. For Zn and Ni, leaching was the main output flux (>95% of the total output) and the plot budget (input-output) was negative, whereas for Pb the biomass net exportation represented 60% of the outputs and the budget was balanced. Cadmium and Cu had intermediate behaviours, with 18% and 30% of the total output relative to biomass exportation, respectively, and the budgets were negative. The net uptake by biomass was particularly important for Pb budgets, less so for Cd and Cu and not very important for Zn and Ni in such forest stands. Copyright © 2010 Elsevier B.V. All rights reserved.

Entity-Based Landscape Modelling to Assess the Impacts of Different Incentives Mechanisms on Argan Forest Dynamics

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Farid El Wahidi

2015-11-01

Full Text Available Illegal occupation of argan forest parcels by local households is a new phenomenon in South West Morocco. This is primarily due to the weakening of traditional common control systems and to the boom of the argan oil price. The scope of this work is to develop a decision support system based on dynamic spatial modelling, allowing to anticipate the land tenure dynamics and their impact on forest stand degradation under different policy scenarios. The model simulates the change of land possession by locals and the forest stand degradation levels. The methodological approach combines a Markov chain analysis (MCA with stakeholders’ preferences for land tenure. First, parcels’ transition probabilities are computed using the MCA. Second, the acquiring suitability map is derived from multi-criteria evaluation procedure (AHP using biophysical and socio-economic data. Finally, uncertainty is introduced in the simulation based on probabilistic analysis for supporting socio-economic diversity and non-mechanistic human behavior. The modelling approach was successfully used to compare three scenarios: business as usual (continuation of illegal acquiring, total disengagement of the population and private/public partnership with incentives for restoring argan parcel. The model yields geographic information about (i the magnitude of the on-going process; (ii the potential occurrence of land use conflicts induced by new policies; and (iii the location of land conservation or degradation hot-spots. The outcomes of the “business as usual” and of the “total disengagement” models were similar over a 30-year simulation period: in both cases, the proportion of “highly degraded” parcels was doubled and the number of “quite degraded” parcels was increased by 50%. On the other hand, should the private/public partnership effectively work, about 40% of the parcels could be restored to a sustainable level.

Spatial variation in the storages and age-related dynamics of forest carbon sequestration in different climate zones-evidence from black locust plantations on the Loess Plateau of China.

Science.gov (United States)

Li, Taijun; Ren, Bowen; Wang, Dahui; Liu, Guobin

2015-01-01

Knowledge about the long-term influences of climate change on the amount of potential carbon (C) sequestration in forest ecosystems, including age-related dynamics, remains unclear. This study used two similar age-sequences of black locust forests (Robinia pseudoacacia L.) in the semi-arid and semi-humid zones of China's Loess Plateau to assess the variation in C stocks and age-related dynamics. Our results demonstrated that black locust forests of the semi-humid zone stored significantly more C than did forests in the semi-arid zone, across the chronosequence (p zone, while the semi-arid zone had a capacity of only 79.4 Mg C ha-1. Soil organic C (SOC) increased continuously with stand age in the semi-arid zone (R2 = 0.84, p = 0.010). However, in the semi-humid zone, SOC declined sharply by 47.8% after the initial stage (5 to 10 y). The C stock in trees increased continuously with stand age in the semi-humid zone (R2 = 0.83, p = 0.011), yet in the semi-arid zone, it decreased dramatically from 43.0 Mg C ha-1 to 28.4 Mg C ha-1 during the old forest stage (38 to 56 y). The shift from being a net C sink to a net C source occurred at the initial stage in the semi-humid zone versus at the old forest stage in the semi-arid zone after reforestation. Surprisingly, with the exception of the initial and later stages (55 y), the patterns of C allocation among trees, soils, understory and litter were not statistically different between the two climate zones. Our results suggest that climate factors can alter the potential amount and age-related dynamics of forest C sequestration.

Spatial Variation in the Storages and Age-Related Dynamics of Forest Carbon Sequestration in Different Climate Zones—Evidence from Black Locust Plantations on the Loess Plateau of China

Science.gov (United States)

Li, Taijun; Ren, Bowen; Wang, Dahui; Liu, Guobin

2015-01-01

Knowledge about the long-term influences of climate change on the amount of potential carbon (C) sequestration in forest ecosystems, including age-related dynamics, remains unclear. This study used two similar age-sequences of black locust forests (Robinia pseudoacacia L.) in the semi-arid and semi-humid zones of China’s Loess Plateau to assess the variation in C stocks and age-related dynamics. Our results demonstrated that black locust forests of the semi-humid zone stored significantly more C than did forests in the semi-arid zone, across the chronosequence (p zone, while the semi-arid zone had a capacity of only 79.4 Mg C ha−1. Soil organic C (SOC) increased continuously with stand age in the semi-arid zone (R2 = 0.84, p = 0.010). However, in the semi-humid zone, SOC declined sharply by 47.8% after the initial stage (5 to 10 y). The C stock in trees increased continuously with stand age in the semi-humid zone (R2 = 0.83, p = 0.011), yet in the semi-arid zone, it decreased dramatically from 43.0 Mg C ha−1 to 28.4 Mg C ha−1 during the old forest stage (38 to 56 y). The shift from being a net C sink to a net C source occurred at the initial stage in the semi-humid zone versus at the old forest stage in the semi-arid zone after reforestation. Surprisingly, with the exception of the initial and later stages (55 y), the patterns of C allocation among trees, soils, understory and litter were not statistically different between the two climate zones. Our results suggest that climate factors can alter the potential amount and age-related dynamics of forest C sequestration. PMID:25799100

OpCost: an open-source system for estimating costs of stand-level forest operations

Science.gov (United States)

Conor K. Bell; Robert F. Keefe; Jeremy S. Fried

2017-01-01

This report describes and documents the OpCost forest operations cost model, a key component of the BioSum analysis framework. OpCost is available in two editions: as a callable module for use with BioSum, and in a stand-alone edition that can be run directly from R. OpCost model logic and assumptions for this open-source tool are explained, references to the...

Carbon Flux of Down Woody Materials in Forests of the North Central United States

International Nuclear Information System (INIS)

Woodall, C.W.

2010-01-01

Across large scales, the carbon (C) flux of down woody material (DWM) detrital pools has largely been simulated based on forest stand attributes (e.g., stand age and forest type). The annual change in forest DWM C stocks and other attributes (e.g., size and decay class changes) was assessed using a forest inventory in the north central United States to provide an empirical assessment of strategic-scale DWM C flux. Using DWM inventory data from the USDA Forest Service's Forest Inventory and Analysis program, DWM C stocks were found to be relatively static across the study region with an annual flux rate not statistically different from zero. Mean C flux rates across the study area were -0.25, -0.12, -0.01, and -0.04 (Mg/ha/yr) for standing live trees, standing dead trees, coarse woody debris, and fine woody debris, respectively. Flux rates varied in their both magnitude and status (emission/sequestration) by forest types, latitude, and DWM component size. Given the complex dynamics of DWM C flux, early implementation of inventory re measurement, and relatively low sample size, numerous future research directions are suggested.

Quantifying geomorphic controls on riparian forest dynamics using a linked physical-biological model: implications for river corridor conservation

Science.gov (United States)

Stella, J. C.; Harper, E. B.; Fremier, A. K.; Hayden, M. K.; Battles, J. J.

2009-12-01

each patch. Model parameters of tree life-history traits (e.g., dispersal timing) and hydrogeomorphic processes (e.g., sedimentation rate) were determined by field and experimental studies, and aerial LIDAR, with separate range of values for point bar versus floodplain habitats. In most runs, abandoned channels were colonized one third as frequently as point bars, but supported much larger forest patches when colonization was successful (from 15-99% of forest area, depending on point bar success). Independent evaluation of aerial photos confirm that cottonwood forest stands associated with abandoned channels were less frequent (38% of all stands) but more extensive (53% of all forest area) relative to those caused by migrating point bars. Results indicate that changes to the rate and scale of river migration, and particularly channel abandonment, from human and climatic alterations to the flow regime will likely influence riparian corridor-wide tree population structure and forest dynamics, with consequences for the community of organisms that depend on this habitat.

Forests

International Nuclear Information System (INIS)

Melin, J.

1997-01-01

Forests have the capacity to trap and retain radionuclides for a substantial period of time. The dynamic behaviour of nutrients, pollution and radionuclides in forests is complex. The rotation period of a forest stand in the Nordic countries is about 100 years, whilst the time for decomposition of organic material in a forest environment can be several hundred years. This means that any countermeasure applied in the forest environment must have an effect for several decades, or be reapplied continuously for long periods of time. To mitigate the detrimental effect of a contaminated forest environment on man, and to minimise the economic loss in trade of contaminated forest products, it is necessary to understand the mechanisms of transfer of radionuclides through the forest environment. It must also be stressed that any countermeasure applied in the forest environment must be evaluated with respect to long, as well as short term, negative effects, before any decision about remedial action is taken. Of the radionuclides studied in forests in the past, radiocaesium has been the main contributor to dose to man. In this document, only radiocaesium will be discussed since data on the impact of other radionuclides on man are too scarce for a proper evaluation. (EG)

The role of forest disturbance in global forest mortality and terrestrial carbon fluxes

Science.gov (United States)

Pugh, Thomas; Arneth, Almut; Smith, Benjamin; Poulter, Benjamin

2017-04-01

Large-scale forest disturbance dynamics such as insect outbreaks, wind-throw and fires, along with anthropogenic disturbances such as logging, have been shown to turn forests from carbon sinks into intermittent sources, often quite dramatically so. There is also increasing evidence that disturbance regimes in many regions are changing as a result of climatic change and human land-management practices. But how these landscape-scale events fit into the wider picture of global tree mortality is not well understood. Do such events dominate global carbon turnover, or are their effects highly regional? How sensitive is global terrestrial carbon exchange to realistic changes in the occurrence rate of such disturbances? Here, we combine recent advances in global satellite observations of stand-replacing forest disturbances and in compilations of forest inventory data, with a global terrestrial ecosystem model which incorporates an explicit representation of the role of disturbance in forest dynamics. We find that stand-replacing disturbances account for a fraction of wood carbon turnover that varies spatially from less than 5% in the tropical rainforest to ca. 50% in the mid latitudes, and as much as 90% in some heavily-managed regions. We contrast the size of the land-atmosphere carbon flux due to this disturbance with other components of the terrestrial carbon budget. In terms of sensitivity, we find a quasi log-linear relationship of disturbance rate to total carbon storage. Relatively small changes in disturbance rates at all latitudes have marked effects on vegetation carbon storage, with potentially very substantial implications for the global terrestrial carbon sink. Our results suggest a surprisingly small effect of disturbance type on large-scale forest vegetation dynamics and carbon storage, with limited evidence of widespread increases in nitrogen limitation as a result of increasing future disturbance. However, the influence of disturbance type on soil carbon

Succession, climate, and neighborhood dynamics influence tree growth over time: an 87-year record of change in a Pinus resinosa (Aiton)-dominated forest, Minnesota, USA

Science.gov (United States)

Miranda T. Curzon; Anthony W. D' Amato; Shawn Fraver; Emily S. Huff; Brian J. Palik

2016-01-01

Resource availability and its influence on tree-to-tree interactions are expected to change over the course of forest stand development, but the rarity of long-term datasets has limited examinations of neighborhood crowding over extended time periods. How do a history of neighborhood interactions and population-level dynamics, including demographic transition, impact...

Overstory tree status following thinning and burning treatments in mixed pine-hardwood stands on the William B. Bankhead National Forest, Alabama

Science.gov (United States)

Callie Jo Schweitzer; Yong Wang

2013-01-01

Prescribed burning and thinning are intermediate stand treatments whose consequences when applied in mixed pine-hardwood stands are unknown. The William B. Bankhead National Forest in northcentral Alabama has undertaken these two options to move unmanaged, 20- to 50-year-old loblolly pine (Pinus taeda L.) plantations towards upland hardwood-dominated...

Southern pine beetle infestations in relation to forest stand conditions, previous thinning, and prescribed burning: evaluation of the Southern Pine Beetle Prevention Program

Science.gov (United States)

John T. Nowak; James R. Meeker; David R. Coyle; Chris A. Steiner; Cavell Brownie

2015-01-01

Since 2003, the Southern Pine Beetle Prevention Program (SPBPP) (a joint effort of the USDA Forest Service and Southern Group of State Foresters) has encouraged and provided cost-share assistance for silvicultural treatments to reduce stand/forest susceptibility to the southern pine beetle (SPB)(Dendroctonus frontalis Zimmermann) in the southeastern United States....

Transformation to near-natural forest management, climate change and uncertainty

DEFF Research Database (Denmark)

Schou, Erik

Currently transformation from even-aged management to near-natural forest management is being considered or undertaken throughout the Atlantic region of Europe. What in general lies in this transformation is the desire for a higher degree of utilisation in forest management of the natural processes...... inherent in the forest ecosystem. The motivations for transforming involve economic, biological and social values. At the same time, potential climate changes are expected to change growing conditions of tree species – possibly having a high impact on future forest growth. The purpose of this dissertation......, the studies of the dissertation analysed changes in stand structure and the choice of species at the stand and forest level. Only the value of timber was considered. Both optimisation and simulation approaches have been applied in the dissertation. Methods include dynamic programming, evolution algorithms...

Multi-aged Forest: an Optimal Management Strategy for Carbon Sequestration

Science.gov (United States)

Yao, L.; Tang, X.; Ma, M.

2017-12-01

Disturbances and climatic changes significantly affect forest ecosystem productivity, water use efficiency (WUE) and carbon (C) flux dynamics. A deep understanding of terrestrial feedbacks to such effects and recovery mechanisms in forests across contrasting climatic regimes is essential to predict future regional/global C and water budgets, which are also closely related to the potential forest management decisions. However, the resilience of multi-aged and even-aged forests to disturbances has been debated for more than 60 years because of technical measurement constraints. Here we evaluated 62 site-years of eddy covariance measurements of net ecosystem production (NEP), evapotranspiration (ET), the estimates of gross primary productivity (GPP), ecosystem respiration (Re) and ecosystem-level WUE, as well as the relationships with environmental controls in three chronosequences of multi- and even-aged coniferous forests covering the Mediterranean, temperate and boreal regions. Age-specific dynamics in multi-year mean annual NEP and WUE revealed that forest age is a key variable that determines the sign and magnitude of recovering forest C source-sink strength from disturbances. However, the trends of annual NEP and WUE across succession stages between two stand structures differed substantially. The successional patterns of NEP exhibited an inverted-U trend with age at the two even-aged chronosequences, whereas NEP of the multi-aged chronosequence increased steadily through time. Meanwhile, site-level WUE of even-aged forests decreased gradually from young to mature, whereas an apparent increase occurred for the same forest age in multi-aged stands. Compared with even-aged forests, multi-aged forests sequestered more CO2 with forest age and maintained a relatively higher WUE in the later succession periods. With regard to the available flux measurements in this study, these behaviors are independent of tree species, stand ages and climate conditions . We also

Spatially dynamic forest management to sustain biodiversity and economic returns.

Science.gov (United States)

Mönkkönen, Mikko; Juutinen, Artti; Mazziotta, Adriano; Miettinen, Kaisa; Podkopaev, Dmitry; Reunanen, Pasi; Salminen, Hannu; Tikkanen, Olli-Pekka

2014-02-15

Production of marketed commodities and protection of biodiversity in natural systems often conflict and thus the continuously expanding human needs for more goods and benefits from global ecosystems urgently calls for strategies to resolve this conflict. In this paper, we addressed what is the potential of a forest landscape to simultaneously produce habitats for species and economic returns, and how the conflict between habitat availability and timber production varies among taxa. Secondly, we aimed at revealing an optimal combination of management regimes that maximizes habitat availability for given levels of economic returns. We used multi-objective optimization tools to analyze data from a boreal forest landscape consisting of about 30,000 forest stands simulated 50 years into future. We included seven alternative management regimes, spanning from the recommended intensive forest management regime to complete set-aside of stands (protection), and ten different taxa representing a wide variety of habitat associations and social values. Our results demonstrate it is possible to achieve large improvements in habitat availability with little loss in economic returns. In general, providing dead-wood associated species with more habitats tended to be more expensive than providing requirements for other species. No management regime alone maximized habitat availability for the species, and systematic use of any single management regime resulted in considerable reductions in economic returns. Compared with an optimal combination of management regimes, a consistent application of the recommended management regime would result in 5% reduction in economic returns and up to 270% reduction in habitat availability. Thus, for all taxa a combination of management regimes was required to achieve the optimum. Refraining from silvicultural thinnings on a proportion of stands should be considered as a cost-effective management in commercial forests to reconcile the conflict

The Missouri Ozark Forest Ecosystem Project: the effects of forest management on the forest ecosystem

Science.gov (United States)

Brian Brookshire; Carl Hauser

1993-01-01

The effects of forest management on non-timber resources are of growing concern to forest managers and the public. While many previous studies have reported effects of stand-level treatments (less than 15 ha) on various stand-level attributes, few studies have attempted to document the influence of forest management on the biotic and abiotic characteristics of entire...

Changes in carbon pool and stand structure of a native subtropical mangrove forest after inter-planting with exotic species Sonneratia apetala.

Science.gov (United States)

Lu, Weizhi; Yang, Shengchang; Chen, Luzhen; Wang, Wenqing; Du, Xiaona; Wang, Canmou; Ma, Yan; Lin, Guangxuan; Lin, Guanghui

2014-01-01

In this study, we compared stand structure, biomass and soil carbon pools, and litterfall production between a mixed mangrove forest consisting of Aegiceras corniculatum inter-planted with the exotic Sonneratia apetala and a native monospecific forest dominated by A. corniculatum in the intertidal area of Zhanjiang, Guangdong Province, southeast China. The goal of this study was to test the hypothesis that inter-planting fast growing exotic mangrove S. apetala into subtropical native mangrove forests will significantly increase C sequestration. Although the tree heights and basal diameters of S. apetala were significantly higher than those of A. corniculatum, the density of the 12-year-old S. apetala trees in the mixed forest was much smaller than that of A. corniculatum in the monospecific forest. In contrast to several previous studies on S. apetala forests planted directly on mangrove-free mudflats, the mixed mangrove forest showed no significant difference in either standing biomass or soil carbon pools from the native monospecific mangrove forest (p = 0.294 and 0.073, respectively) twelve years after inter-planting with S. apetala. Moreover, carbon cycling was likely speeded up after inter-planting S. apetala due to higher litterfall input and lower C/N ratio. Thus, inter-planting fast-growing S. apetala into native mangrove forest is not an effective way to increase carbon sequestration in this subtropical mangrove forest. Given that exotic plant species may exert negative impact on native mangrove species and related epifauna, this fast-growing mangrove species is not suitable for mangrove plantation projects aiming mainly at enhancing carbon sequestration.

Forest attributes and fuel loads of riparian vs. upland stands in mountain pine beetle infested watersheds, southern Rocky Mountains [Chapter 13

Science.gov (United States)

Kathleen A. Dwire; Roberto A. Bazan; Robert Hubbard

2015-01-01

Extensive outbreaks of mountain pine beetle (MPB), spruce beetle (SB), and other insects are altering forest stand structure throughout the Western United States, and thereby increasing the natural heterogeneity of fuel distribution. Riparian forests frequently occur as narrow linear features in the landscape mosaic and can contribute to the spatial complexity of...

Deciduous birch canopy as unexpected contributor to stand level atmospheric reactivity in boreal forests

Science.gov (United States)

Bäck, Jaana; Taipale, Ditte; Aalto, Juho

2017-04-01

In boreal forests, deciduous trees such as birches may in future climate become more abundant due to their large biomass production capacity, relatively good resource use ability and large acclimation potential to elevated CO2 levels and warmer climate. Increase in birch abundance may lead to unpredicted consequences in atmospheric composition. Currently it is acknowledged that conifers such as Scots pine and Norway spruce are important sources for volatile organic compounds (VOCs), especially monoterpenes, throughout the year, although the strong temperature relationships implies that emissions are highest in summertime. However, the dynamics of the deciduous birch foliage VOC emissions and their relationship with environmental drivers during the development, maturation and senescence of foliage has not been well analyzed. Long-term measurements of birch, which are unfortunately very sparse, can provide very useful information for the development of biosphere-atmosphere models that simulate boreal and subarctic forested areas where birch is often a sub-canopy species, occurs as a mixture among conifers or forms even pure stands in the higher latitudes. We measured the branch level VOC emissions from a mature Silver birch with proton transfer reaction mass spectrometer during 2014 and 2015 at the SMEAR II station (Station for Measuring Ecosystem-Atmosphere Relations), southern Finland. Our results showed that the Silver birch foliage is a huge source for both short-chained volatiles such as methanol, acetaldehyde and acetone, as well as for monoterpenes. The mean emission rates from birch leaves were 5 to 10 times higher than the corresponding emissions from Scots pine shoots. We compared several semi-empirical model approaches for determining the birch foliage monoterpene standardized emission potentials, and utilized the continuous emission measurements from the two growing seasons for development of a novel algorithm which accounts for the leaf development and

Forests and Forest Cover - MDC_NaturalForestCommunity

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — A point feature class of NFCs - Natural Forest Communities. Natural Forest Community shall mean all stands of trees (including their associated understory) which...

Ground Monitoring Neotropical Dry Forests: A Sensor Network for Forest and Microclimate Dynamics in Semi-Arid Environments (Enviro-Net°)

Science.gov (United States)

Rankine, C. J.; Sánchez-Azofeifa, G.

2011-12-01

In the face of unprecedented global change driven by anthropogenic pressure on natural systems it has become imperative to monitor and better understand potential shifts in ecosystem functioning and services from local to global scales. The utilization of automated sensors technologies offers numerous advantages over traditional on-site ecosystem surveying techniques and, as a result, sensor networks are becoming a powerful tool in environmental monitoring programs. Tropical forests, renowned for their biodiversity, are important regulators of land-atmosphere fluxes yet the seasonally dry tropical forests, which account for 40% of forested ecosystems in the American tropics, have been severely degraded over the past several decades and not much is known of their capacity to recover. With less than 1% of these forests protected, our ability to monitor the dynamics and quantify changes in the remaining primary and recovering secondary tropical dry forests is vital to understanding mechanisms of ecosystem stress responses and climate feedback with respect to annual productivity and desertification processes in the tropics. The remote sensing component of the Tropi-Dry: Human and Biophysical Dimensions of Tropical Dry Forests in the Americas research network supports a network of long-term tropical ecosystem monitoring platforms which focus on the dynamics of seasonally dry tropical forests in the Americas. With over 25 sensor station deployments operating across a latitudinal gradient in Mexico, Costa Rica, Brazil, and Argentina continuously collecting hyper-temporal sensory input based on standardized deployment parameters, this monitoring system is unique among tropical environments. Technologies used in the network include optical canopy phenology towers, understory wireless sensing networks, above and below ground microclimate stations, and digital cameras. Sensory data streams are uploaded to a cyber-infrastructure initiative, denominated Enviro-Net°, for data

New and interesting lichen records from old-growth forest stands in the German National Park Bayerischer Wald

Czech Academy of Sciences Publication Activity Database

Printzen, C.; Halda, J.; Palice, Zdeněk; Toensberg, T.

2002-01-01

Roč. 74, 1-2 (2002), s. 25-49 ISSN 0029-5035 R&D Projects: GA AV ČR KSK6005114 Institutional research plan: CEZ:AV0Z6005908 Keywords : lichens * forest stands * Bayerischer Wald National Park Subject RIV: EF - Botanics Impact factor: 0.588, year: 2002

Dynamic response of the scenic beauty value of different forests to various thinning intensities in central eastern China.

Science.gov (United States)

Deng, Songqiu; Yin, Na; Guan, Qingwei; Katoh, Masato

2014-11-01

Forest management has a significant influence on the preferences of people for forest landscapes. This study sought to evaluate the dynamic effects of thinning intensities on the landscape value of forests over time. Five typical stands in Wuxiangsi National Forest Park in Nanjing, China, were subjected to a thinning experiment designed with four intensities: unthinned, light thinning, moderate thinning, and heavy thinning. People's preferences for landscape photographs taken in plots under various thinning intensities were assessed through scenic beauty estimation (SBE) at 2 and 5 years after thinning. The differences in scenic beauty value between different thinning intensities were then analyzed with a paired samples t test for the two periods. The results indicated that the landscape value of all of the thinned plots significantly exceeded that of the unthinned plots 2 years after thinning (p beautiful than the lightly thinned and moderately thinned plots, whereas there was no significant difference between moderate thinning and light thinning. At 5 years after thinning, however, the moderately thinned plots received the highest preference scores among the four intensities, displaying an average improvement of 11.32 % compared with the unthinned plots. A multiple linear regression (MLR) model indicated that landscape value improved with increases in the average diameter at breast height (DBH) and with the improvement of environmental cleanliness in the stand, whereas the value decreased with an increasing stem density, species diversity, litter coverage, and canopy density. In addition, we found that the performance of a neural network model based on a multilayer perception (MLP) algorithm for predicting scenic beauty was slightly better than that of the MLR model. The findings of our study suggest that moderate to heavy thinning should be recommended to manage forests for the improvement of forest landscape value.

Spatio-temporal dynamics of the tropical rain forest

Energy Technology Data Exchange (ETDEWEB)

Chave, J. [CEN Saclay, Gif-sur-Yvette (France). Service de Physique de l' Etat Condense

2000-07-01

Mechanisms which drive the dynamics of forest ecosystems are complex, from seedling establishment to pollination, and seed dispersal by animals, running water or wind. These processes are more complex when the ecosystem shelters a large number of species and of vegetative forms, as it is the case in the tropical rainforest. To take them into account, we must develop and use models. I present a review of the fundamental mechanisms for the of a natural forest dynamics - photosynthesis, tree growth, recruitment and mortality - as well as a description of the past and of the present of tropical rainforests. This information is used to develop a spatially-explicit and individual-based forest model. Simplified models are deduced from it, and they serve to address more specific issues, such as the resilience of the forest to climate disturbances, or savanna-forest dynamics. The last topic is related to the spatio-temporal description of tropical plant biodiversity. A detailed introduction to the problem is provided, and models accounting for the maintenance of diversity are compared. These models include non spatial as well a spatial approaches (branching anihilating random walks and voter model with mutation). (orig.)

Addressing climate change in the Forest Vegetation Simulator to assess impacts on landscape forest dynamics

Science.gov (United States)

Nicholas L. Crookston; Gerald E. Rehfeldt; Gary E. Dixon; Aaron R. Weiskittel

2010-01-01

To simulate stand-level impacts of climate change, predictors in the widely used Forest Vegetation Simulator (FVS) were adjusted to account for expected climate effects. This was accomplished by: (1) adding functions that link mortality and regeneration of species to climate variables expressing climatic suitability, (2) constructing a function linking site index to...

Decadal-Scale Reduction in Forest Net Ecosystem Production Following Insect Defoliation Contrasts with Short-Term Impacts of Prescribed Fires

Science.gov (United States)

Kenneth L. Clark; Heidi J. Renninger; Nicholas Skowronski; Michael Gallagher; Karina V.R.  Schäfer

2018-01-01

Understanding processes underlying forest carbon dynamics is essential for accurately predicting the outcomes of non-stand-replacing disturbance in intermediate-age forests. We quantified net ecosystem production (NEP), aboveground net primary production (ANPP), and the dynamics of major carbon (C) pools before and during the decade following invasive insect...

Rebuilding after collapse: evidence for long-term cohort dynamics in the native Hawaiian rain forest

Science.gov (United States)

Boehmer, Hans Juergen; Wagner, Helene H.; Jacobi, James D.; Gerrish, Grant C.; Mueller-Dombois, Dieter

2013-01-01

Questions: Do long-term observations in permanent plots confirm the conceptual model of Metrosideros polymorpha cohort dynamics as postulated in 1987? Do regeneration patterns occur independently of substrate age, i.e. of direct volcanic disturbance impact? Location: The windward mountain slopes of the younger Mauna Loa and the older Mauna Kea volcanoes (island of Hawaii, USA). Methods: After widespread forest decline (dieback), permanent plots were established in 1976 in 13 dieback and 13 non-dieback patches to monitor the population structure of M. polymorpha at ca. 5-yr intervals. Within each plot of 20 × 20 m, all trees with DBH >2.5 cm were individually tagged, measured and tree vigour assessed; regeneration was quantified in 16 systematically placed subplots of 3 × 5 m. Data collected in the subplots included the total number of M. polymorpha seedlings and saplings (five stem height classes). Here we analyse monitoring data from six time steps from 1976 to 2003 using repeated measures ANOVA to test specific predictions derived from the 1987 conceptual model. Results: Regeneration was significantly different between dieback and non-dieback plots. In dieback plots, the collapse in the 1970s was followed by a ‘sapling wave’ that by 2003 led to new cohort stands of M. polymorpha. In non-dieback stands, seedling emergence did not result in sapling waves over the same period. Instead, a ‘sapling gap’ (i.e. very few or no M. polymorpha saplings) prevailed as typical for mature stands. Canopy dieback in 1976, degree of recovery by 2003 and the number of living trees in 2003 were unrelated to substrate age. Conclusions: Population development of M. polymorpha supports the cohort dynamics model, which predicts rebuilding of the forest with the same canopy species after dieback. The lack of association with substrate age suggests that the long-term maintenance of cohort structure in M. polymorpha does not depend on volcanic disturbance but may be related to

新疆森林资源动态分析%Dynamic analysis and evaluation of Xinjiang forest resources: based on RS and GIS

Institute of Scientific and Technical Information of China (English)

李虎; 王晓峰; 陈蜀疆

2005-01-01

The forest resources in Xinjiang were surveyed and analyzed based on RS and GIS. Satellite data interpretation was adopted to obtain the general situation of Xinjiang forest resources in assistance with the sampling method and on-the-spot investigations. Based on GIS, related data obtained from satellite remote sensing in 1996 and 2001 were studied through contrastive analysis. Moreover, the dynamic variation of Xinjiang forest resources was studied in an all-around way. In the past five years,the areas of the forestland, woodland, sparse woodland, nursery garden and the land usable for forestry in Xinjiang kept growing, moreover, the forest cover rate and the total standing stock volume increased correspondingly, showing that the wooded area and the amount of growing stock in Xinjiang were increasing. The forestland area in Xinjiang went up to 17,837 km2 from 17,331 km2, with an annual average increase of 101 km2. Accordingly, the forest vegetation came to 1.08% from 1.05%, up 0.03percentage point; the total standing stock volume went up to 289,985,200 m3 from 262,416,000 m3, a total increase of 27,569,200 m3, an annual average increase of 5,514,000 m3 and an annual average net growth rate of 2.00%. The analysis results showed that the forest resources in Xinjiang were increasing on the whole, however, there remained some problems, such as the sparse natural forests, low forest cover rate, imbalanced wood age structure, and mono tree species composition, etc.

From a tree to a stand in Finnish boreal forests - biomass estimation and comparison of methods

Energy Technology Data Exchange (ETDEWEB)

Liu, Chunjiang

2009-07-01

There is an increasing need to compare the results obtained with different methods of estimation of tree biomass in order to reduce the uncertainty in the assessment of forest biomass carbon. In this study, tree biomass was investigated in a 30-year-old Scots pine (Pinus sylvestris) (Young-Stand) and a 130-year-old mixed Norway spruce (Picea abies)-Scots pine stand (Mature-Stand) located in southern Finland (61deg50' N, 24deg22' E). In particular, a comparison of the results of different estimation methods was conducted to assess the reliability and suitability of their applications. For the trees in Mature-Stand, annual stem biomass increment fluctuated following a sigmoid equation, and the fitting curves reached a maximum level (from about 1 kg yr-1 for understorey spruce to 7 kg yr-1 for dominant pine) when the trees were 100 years old). Tree biomass was estimated to be about 70 Mg ha-1 in Young-Stand and about 220 Mg ha-1 in Mature-Stand. In the region (58.00-62.13 degN, 14-34 degE, <= 300 m a.s.l.) surrounding the study stands, the tree biomass accumulation in Norway spruce and Scots pine stands followed a sigmoid equation with stand age, with a maximum of 230 Mg ha-1 at the age of 140 years. In Mature-Stand, lichen biomass on the trees was 1.63 Mg ha-1 with more than half of the biomass occurring on dead branches, and the standing crop of litter lichen on the ground was about 0.09 Mg ha-1. There were substantial differences among the results estimated by different methods in the stands. These results imply that a possible estimation error should be taken into account when calculating tree biomass in a stand with an indirect approach. (orig.)

Biodiversity of animals that are living on the surface of soil under the forest stands surrounding Japan Cave of BKPH Nglerak, North Lawu, Karanganyar

Directory of Open Access Journals (Sweden)

DHINI WIJAYA

2002-01-01

Full Text Available The study of animal biodiversity that lived on the surface of soil under the stands forest surround Japan Cave BKPH Nglerak, North Lawu, Karanganyar has bee done. Observations were conducted in 6 stations of different stands of forest. Animals were caught by pit fall trap method. In each catching was found about 22 animals consisting of 6 families with Simpson’s diversity index of 0.5. The result of identification indicates that those animals belong to 4 classes: Insects (9 orders, Arachnids (2 orders, Diplopods (2 orders, and Crustacean (1 order. The most diverse animals was found in the habitat of pine stands while the lowest one found in the habitat of cultivated plants.

Analysis of tree stand horizontal structure using random point field methods

Directory of Open Access Journals (Sweden)

O. P. Sekretenko

2015-06-01

Full Text Available This paper uses the model approach to analyze the horizontal structure of forest stands. The main types of models of random point fields and statistical procedures that can be used to analyze spatial patterns of trees of uneven and even-aged stands are described. We show how modern methods of spatial statistics can be used to address one of the objectives of forestry – to clarify the laws of natural thinning of forest stand and the corresponding changes in its spatial structure over time. Studying natural forest thinning, we describe the consecutive stages of modeling: selection of the appropriate parametric model, parameter estimation and generation of point patterns in accordance with the selected model, the selection of statistical functions to describe the horizontal structure of forest stands and testing of statistical hypotheses. We show the possibilities of a specialized software package, spatstat, which is designed to meet the challenges of spatial statistics and provides software support for modern methods of analysis of spatial data. We show that a model of stand thinning that does not consider inter-tree interaction can project the size distribution of the trees properly, but the spatial pattern of the modeled stand is not quite consistent with observed data. Using data of three even-aged pine forest stands of 25, 55, and 90-years old, we demonstrate that the spatial point process models are useful for combining measurements in the forest stands of different ages to study the forest stand natural thinning.

Forests

Science.gov (United States)

Louis R. Iverson; Mark W. Schwartz

1994-01-01

Originally diminished by development, forests are coming back: forest biomass is accumulating. Forests are repositories for many threatened species. Even with increased standing timber, however, biodiversity is threatened by increased forest fragmentation and by exotic species.

Ground beetles as indicators of past management of old-growth forests

Directory of Open Access Journals (Sweden)

Mazzei A

2017-06-01

Full Text Available Old-growth forests are terrestrial ecosystems with the highest level of biodiversity and the main environments for the study of conservation and dynamics of the forest system. In Mediterranean Europe, two millennia of human exploitation deeply altered the structural complexity of the native forests. Some animal groups, including insects, may be used as a proxy of such changes. In this paper we explored the possible effects of forest management on the functional diversity (species traits of carabid beetle communities. Three old-growth forests of the Sila National Park were sampled by pitfall traps set up in pure beech, beech-silver fir and Calabrian black pine forests. In each forest, five managed vs. five unmanaged stands were considered. Managed sites were exploited until the sixties of the past century and then left unmanaged. More than 6000 carabid specimens belonging to 23 species were collected. The functional diversity in carabid groups is influenced by forest management especially in beech and beech-silver fir stands. Body size, specialized predators, endemic species and forest species were negatively affected by stand management. On the contrary, omnivorous ground beetles populations (or species with a high dispersal power (macropterous and large geographic distribution were positively influenced by stand management. In pine forests the old-growth community seems less sensitive to past management and more affected by soil evolution. Soil erosion and disturbance may reduce species diversity of ground beetles. Anyway, the composition of the carabid community shows that 50-60 years of forest restoration are enough for the reconstruction of a fairly diverse assemblage reflecting a “subclimax” situation.

Habitat use by forest bats in South Carolina in relation to local, stand, and landscape characteristics

Science.gov (United States)

Susan C. Loeb; Joy M. O' Keefe

2006-01-01

Knowledge and understanding of bat habitat associations and the responses of bats to forest management are critical for effective bat conservation and management. Few studies have been conducted on bat habitat use in the southeast, despite the high number of endangered and sensitive species in the region. Our objective was to identify important local, stand, and...

Selection of roosting habitat by forest bats in a diverse forested landscape

Science.gov (United States)

Roger W. Perry; Ronald E. Thill; David M. Leslie

2007-01-01

Many studies of roost selection by forest-dwelling bats have concentrated on microhabitat surrounding roosts without providing forest stand level preferences of bats; thus, those studies have provided only part of the information needed by managers. We evaluated diurnal summer roost selection by the bat community at the forest-stand level in a diversely forested...

Soil Respiration Declines Following Beetle - Induced Forest Mortality in a Lodgepole Pine Forest

Science.gov (United States)

Borkhuu, B.; Peckham, S. D.; Norton, U.; Ewers, B. E.; Pendall, E.

2014-12-01

Lodgepole pine (Pinus contorta var. latifolia) forests in northern Colorado and southeast Wyoming have been undergoing a major mortality event owing to mountain pine beetle (Dendroctonus ponderosae) infestation since 2007. We studied biotic and abiotic drivers of growing season soil respiration in four mature stands experiencing different levels of mortality between 2008 and 2012 in the Medicine Bow Mountains, southeastern Wyoming, USA. For five years, beetle infestation significantly altered forest structure. Stand mortality was 30% and more than 80% in stands with the lowest and highest mortality, respectively. Understory vegetation cover increased by 50% for five years following beetle infestation. Needlefall was increased by more than 50% during first two years of beetle infestation compared to the pre-disturbance period. We did not observe an immediate increase in soil respiration following beetle infestation as suggested by some researchers. Soil respiration rates in midsummer ranged from 1.4 ± 0.1 μmol m-2 s-1 in stands with highest mortality to 3.1 ± 0.2 μmol m-2s-1 in uninfested stand. Live tree basal area was the dominant factor controlling soil respiration, explaining more than 60% of the interannual and spatial variations in response to the disturbance. In addition, soil respiration was significantly correlated with fine root biomass, which explained 55% of variations, providing strong evidence that autotrophic respiration dominated the forest soil respiration flux. Furthermore, the seasonality of soil respiration was controlled mainly by mean monthly precipitation and mid-day photosynthetically active radiation. Each factor predicted from 30% to 50% of seasonal soil respiration variability with the highest correlation coefficients in stand with the lowest mortality. Our results clearly indicate that the reduction of photosynthesis in trees over the infestation period significantly reduced soil respiration. The remaining activity in dead stands may

Retrieving forest stand parameters from SAR backscatter data using a neural network trained by a canopy backscatter model

International Nuclear Information System (INIS)

Wang, Y.; Dong, D.

1997-01-01

It was possible to retrieve the stand mean dbh (tree trunk diameter at breast height) and stand density from the Jet Propulsion Laboratory (JPL) Airborne Synthetic Aperture Radar (AIRSAR) backscatter data by using threelayered perceptron neural networks (NNs). Two sets of NNs were trained by the Santa Barbara microwave canopy backscatter model. One set of the trained NNs was used to retrieve the stand mean dbh, and the other to retrieve the stand density. Each set of the NNs consisted of seven individual NNs for all possible combinations of one, two, and three radar wavelengths. Ground and multiple wavelength AIRSAR backscatter data from two ponderosa pine forest stands near Mt. Shasta, California (U.S.A.) were used to evaluate the accuracy of the retrievals. The r.m.s. and relative errors of the retrieval for stand mean dbh were 6.1 cm and 15.6 per cent for one stand (St2), and 3.1 cm and 6.7 per cent for the other stand (St11). The r.m.s. and relative errors of the retrieval for stand density were 71.2 treesha-1 and 23.0 per cent for St2, and 49.7 treesha-1 and 21.3 per cent for St11. (author)

N-15 tracing helps explaining N leaching losses from contrasting forest ecosystems

Science.gov (United States)

Staelens, J.; Rütting, T.; Huygens, D.; Müller, C.; Verheyen, K.; Boeckx, P.

2009-04-01

Despite chronically enhanced nitrogen (N) deposition to forest ecosystems in Europe and NE America, considerable N retention by forests has been observed, reducing N leaching losses. Organic and mineral soil layers typically immobilize more N than the aboveground biomass, but it is unclear which factors determine N retention in forest ecoystems. However, this knowledge is crucial to assess the impact of changing anthropogenic N emissions on future N cycling and N loss of forests. For coniferous and deciduous forest stands at comparable sites, it is known that both N deposition onto the forest floor as well as N loss by leaching below the rooting zone are significantly higher in coniferous stands. In addition, the N loss in coniferous stands is often more enhanced than can be explained by the higher N input only. This suggests lower N retention by coniferous stands, and may be related to differences in litter and soil characteristics, microbial activity, and N uptake by plant roots. To test this hypothesis, we studied the effect of forest type on N retention using 15N tracing techniques: a field tracer experiment and a combination of in situ isotope pool dilution and a tracing model. The N dynamics were examined for two adjacent forest stands (pedunculate oak (Quercus robur L.) and Scots pine (Pinus sylvestris L.)) on a well-drained sandy soil and with a similar stand history, located in a region with high N deposition (Belgium). Input-output N budgets were established by quantifying atmospheric deposition and leaching below the rooting zone, and confirmed the above finding of higher N deposition and disproportionately higher N loss for the pine stand compared to the oak stand. First, the fate of inorganic N within the ecosystems was studied by spraying three pulses of dissolved 15N, either as ammonium or as nitrate, onto the forest floor in 12 plots of 25 m2. The organic and mineral soil layers, tree roots, soil water percolate, ferns, and tree foliage were sampled

Dynamic behavior of microscale particles controlled by standing bulk acoustic waves

Energy Technology Data Exchange (ETDEWEB)

Greenhall, J.; Raeymaekers, B., E-mail: bart.raeymaekers@utah.edu [Department of Mechanical Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Guevara Vasquez, F. [Department of Mathematics, University of Utah, Salt Lake City, Utah 84112 (United States)

2014-10-06

We analyze the dynamic behavior of a spherical microparticle submerged in a fluid medium, driven to the node of a standing bulk acoustic wave created by two opposing transducers. We derive the dynamics of the fluid-particle system taking into account the acoustic radiation force and the time-dependent and time-independent drag force acting on the particle. Using this dynamic model, we characterize the transient and steady-state behavior of the fluid-particle system as a function of the particle and fluid properties and the transducer operating parameters. The results show that the settling time and percent overshoot of the particle trajectory are dependent on the ratio of the acoustic radiation force and time-independent damping force. In addition, we show that the particle oscillates around the node of the standing wave with an amplitude that depends on the ratio of the time-dependent drag forces and the particle inertia.

User's manual for FORAR: a stand model for composition and growth of upland forests of southern Arkansas

Energy Technology Data Exchange (ETDEWEB)

Mielke, D. L.; Shugart, H. H.; West, D. C.

1977-04-01

This report is a user's manual for FORAR, a computer model simulating stand growth and composition of upland forests of south central Arkansas. The model computes: the number and biomass of each tree species, and the dbh, age, and species of each individual tree on a 1/12-ha circular plot.

Allometric Scaling and Resource Limitations Model of Total Aboveground Biomass in Forest Stands: Site-scale Test of Model

Science.gov (United States)

CHOI, S.; Shi, Y.; Ni, X.; Simard, M.; Myneni, R. B.

2013-12-01

Sparseness in in-situ observations has precluded the spatially explicit and accurate mapping of forest biomass. The need for large-scale maps has raised various approaches implementing conjugations between forest biomass and geospatial predictors such as climate, forest type, soil property, and topography. Despite the improved modeling techniques (e.g., machine learning and spatial statistics), a common limitation is that biophysical mechanisms governing tree growth are neglected in these black-box type models. The absence of a priori knowledge may lead to false interpretation of modeled results or unexplainable shifts in outputs due to the inconsistent training samples or study sites. Here, we present a gray-box approach combining known biophysical processes and geospatial predictors through parametric optimizations (inversion of reference measures). Total aboveground biomass in forest stands is estimated by incorporating the Forest Inventory and Analysis (FIA) and Parameter-elevation Regressions on Independent Slopes Model (PRISM). Two main premises of this research are: (a) The Allometric Scaling and Resource Limitations (ASRL) theory can provide a relationship between tree geometry and local resource availability constrained by environmental conditions; and (b) The zeroth order theory (size-frequency distribution) can expand individual tree allometry into total aboveground biomass at the forest stand level. In addition to the FIA estimates, two reference maps from the National Biomass and Carbon Dataset (NBCD) and U.S. Forest Service (USFS) were produced to evaluate the model. This research focuses on a site-scale test of the biomass model to explore the robustness of predictors, and to potentially improve models using additional geospatial predictors such as climatic variables, vegetation indices, soil properties, and lidar-/radar-derived altimetry products (or existing forest canopy height maps). As results, the optimized ASRL estimates satisfactorily

Nitrogen, phosphorus, and cation use efficiency in stands of regenerating tropical dry forest.

Science.gov (United States)

Waring, Bonnie G; Becknell, Justin M; Powers, Jennifer S

2015-07-01

Plants on infertile soils exhibit physiological and morphological traits that support conservative internal nutrient cycling. However, potential trade-offs among use efficiencies for N, P, and cations are not well explored in species-rich habitats where multiple elements may limit plant production. We examined uptake efficiency and use efficiency of N, P, K, Ca, Mg, Al, and Na in plots of regenerating tropical dry forests spanning a gradient of soil fertility. Our aim was to determine whether plant responses to multiple elements are correlated, or whether there are trade-offs among exploitation strategies across stands varying in community composition, soil quality, and successional stage. For all elements, both uptake efficiency and use efficiency decreased as availability of the corresponding element increased. Plant responses to N, Na, and Al were uncoupled from uptake and use efficiencies for P and essential base cations, which were tightly correlated. N and P use efficiencies were associated with shifts in plant species composition along the soil fertility gradient, and there was also a trend towards increasing N use efficiency with stand age. N uptake efficiency was positively correlated with the abundance of tree species that associate with ectomycorrhizal fungi. Taken together, our results suggest that successional processes and local species composition interact to regulate plant responses to availability of multiple resources. Successional tropical dry forests appear to employ different strategies to maximize response to N vs. P and K.

An integer programming model for a forest harvest problem in Pinus pinaster stands

Energy Technology Data Exchange (ETDEWEB)

Fonseca, T. F.; Cerveira, A.; Mota, A.

2012-11-01

The study addresses the special case of a management plan for maritime pine (Pinus pinaster Ait.) in common lands. The study area refers to 4,432 ha of maritime pine stands in North Portugal (Perimetro Florestal do Barroso in the county of Ribeira de Pena), distributed among five common lands called baldio areas. Those lands are co-managed by the Official Forest Services and the local communities, essentially for timber production, using empirical guidance. As the current procedure does not guarantee the best thinning and clear-cutting scheduling, it was considered important to develop easy-to-use models, supported by optimization techniques, to be employed by the forest managers in the harvest planning of these communitarian forests. Planning of the thinning and clear-cutting operations involved certain conditions, such as: (1) the optimal age for harvesting; (2) the maximum stand density permitted; (3) the minimum volume to be cut; (4) the guarantee of incomes for each of the five baldios in at least a two year period; (5) balanced incomes during the length of the projection period. In order to evaluate the sustainability of the wood resources, a set of constraints lower bounding the average ending age was additionally tested. The problem was formulated as an integer linear programming model where the incomes from thinning and clear-cutting are maximized while considering the constraints mentioned above. Five major scenarios were simulated. The simplest one allows for silvicultural constraints only, whereas the other four consider these constraints besides different management options. Two of them introduce joint management of all common areas with or without constraints addressing balanced distribution of incomes during the plan horizon, whilst the other two consider the same options but for individual management of the baldios. The proposed model is easy to apply, providing immediate advantages for short and mid-term planning periods compared to the empirical

Effects of dwarf mistletoe on stand structure of lodgepole pine forests 21-28 years post-mountain pine beetle epidemic in central Oregon

Science.gov (United States)

Michelle C. Agne; David C. Shaw; Travis J. Woolley; Mónica E. Queijeiro-Bolaños; Mai-He. Li

2014-01-01

Lodgepole pine (Pinus contorta) forests are widely distributed throughout North America and are subject to mountain pine beetle (Dendroctonus ponderosae) epidemics, which have caused mortality over millions of hectares of mature trees in recent decades. Mountain pine beetle is known to influence stand structure, and has the ability to impact many forest processes....

Basin-wide variations in Amazon forest structure and function are mediated by both soils and climate

Science.gov (United States)

Quesada, C. A.; Phillips, O. L.; Schwarz, M.; Czimczik, C. I.; Baker, T. R.; Patiño, S.; Fyllas, N. M.; Hodnett, M. G.; Herrera, R.; Almeida, S.; Alvarez Dávila, E.; Arneth, A.; Arroyo, L.; Chao, K. J.; Dezzeo, N.; Erwin, T.; di Fiore, A.; Higuchi, N.; Honorio Coronado, E.; Jimenez, E. M.; Killeen, T.; Lezama, A. T.; Lloyd, G.; López-González, G.; Luizão, F. J.; Malhi, Y.; Monteagudo, A.; Neill, D. A.; Núñez Vargas, P.; Paiva, R.; Peacock, J.; Peñuela, M. C.; Peña Cruz, A.; Pitman, N.; Priante Filho, N.; Prieto, A.; Ramírez, H.; Rudas, A.; Salomão, R.; Santos, A. J. B.; Schmerler, J.; Silva, N.; Silveira, M.; Vásquez, R.; Vieira, I.; Terborgh, J.; Lloyd, J.

2012-06-01

Forest structure and dynamics vary across the Amazon Basin in an east-west gradient coincident with variations in soil fertility and geology. This has resulted in the hypothesis that soil fertility may play an important role in explaining Basin-wide variations in forest biomass, growth and stem turnover rates. Soil samples were collected in a total of 59 different forest plots across the Amazon Basin and analysed for exchangeable cations, carbon, nitrogen and pH, with several phosphorus fractions of likely different plant availability also quantified. Physical properties were additionally examined and an index of soil physical quality developed. Bivariate relationships of soil and climatic properties with above-ground wood productivity, stand-level tree turnover rates, above-ground wood biomass and wood density were first examined with multivariate regression models then applied. Both forms of analysis were undertaken with and without considerations regarding the underlying spatial structure of the dataset. Despite the presence of autocorrelated spatial structures complicating many analyses, forest structure and dynamics were found to be strongly and quantitatively related to edaphic as well as climatic conditions. Basin-wide differences in stand-level turnover rates are mostly influenced by soil physical properties with variations in rates of coarse wood production mostly related to soil phosphorus status. Total soil P was a better predictor of wood production rates than any of the fractionated organic- or inorganic-P pools. This suggests that it is not only the immediately available P forms, but probably the entire soil phosphorus pool that is interacting with forest growth on longer timescales. A role for soil potassium in modulating Amazon forest dynamics through its effects on stand-level wood density was also detected. Taking this into account, otherwise enigmatic variations in stand-level biomass across the Basin were then accounted for through the

Stand development and population dynamics of curlleaf mountain mahogany (Cercocarpus ledifolius Nutt.) woodlands in Utah's Bear River Mountains

Science.gov (United States)

Seth A. Ex; Robert DeRose; James N. Long

2011-01-01

Curlleaf mountain mahogany (Cercocarpus ledifolius Nutt.) is a little-studied woodland tree that occurs in pure stands throughout the Intermountain West. Stand development and population dynamics of this species are poorly understood, despite their relevance to management. We describe here the development of stand age structures and population dynamics of mahogany...

Cisovka - the relic population of Abies alba and its relationship to man-made silver-fir stands in Białowieża primeval forest

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Leon Mejnartowicz

2014-01-01

Full Text Available In Białowieża Primeval Forest, in 1823 Stanisław Górski discovered on the Cisovka Hag, a relic population of European silver-fir (Abies alba Mill.. This population is isolated and most away, 120 km to the North-East, from the border of European-silver-fir distribution. Besides the natural population Cisovka, there are also man-made silver fir stands and clumps in the Polish and Belorussian part of Białowieża Primeval Forest. In the Polish part there are four such artificial stands. If the seed-producing silver-fir stands really originated from the Cisovka population, then they are a very valuable part of the declining population and an easy accessible seed source. However, if these populations were introduced to the Białowieża Primeval Forest, then they are a potential source of dangerous genetic pollution of the Cisovka population. The relationship of the genetic structure of the Cisovka population to man-made silver-fir-stands in Białowieża Forest was investigated with the help of 17 loci of 1 1 enzyme systems. Genetic diversity of Cisovka population is characterized by the smallest mean number of alleles per locus (Mal= 1.353, includes all loci studied and per polimorphic locus Malp = 2.00. In Cisovka population there is very low-grade of polimorphic loci (Pp = 11.765 with the mean 37.255 for all studied populations. Expected heterozygosity, He = 0.079 revealed very low-grade of genetic diversity in the population. The observed heterozygosity (Ho = 0.123 was similar to this characterictic in other populations. A dendrogram based on Neis genetic distance coefficient (D among 9 silver-fir populations was constructed. Cisovka in the UPGMA dendrogram is a distinct population separated from other ones by a very great genetic distance (D = 0.06. Also two man-made silver-fir (B I and 132 stands are separated from others. Only populations B3 and B4 are combined into one subgroup linked to the population Tomaszów Lubelski. Basing on the

FlorNExT®, a cloud computing application to estimate growth and yield of maritime pine (Pinus pinaster Ait. stands in Northeastern Portugal

Directory of Open Access Journals (Sweden)

Fernando Pérez-Rodríguez

2016-07-01

Full Text Available Aim of the study: To introduce and describe FlorNExT®, a free cloud computing application to estimate growth and yield of maritime pine (Pinus pinaster Ait. even-aged stands in the Northeast of Portugal (NE Portugal. Area of study: NE Portugal. Material and methods: FlorNExT® implements a dynamic growth and yield modelling framework which integrates transition functions for dominant height (site index curves and basal area, as well as output functions for tree and stand volume, biomass, and carbon content. Main results: FlorNExT® is freely available from any device with an Internet connection at: http://flornext.esa.ipb.pt/. Research highlights: This application has been designed to make it possible for any stakeholder to easily estimate standing volume, biomass, and carbon content in maritime pine stands from stand data, as well as to estimate growth and yield based on four stand variables: age, density, dominant height, and basal area. FlorNExT® allows planning thinning treatments. FlorNExT® is a fundamental tool to support forest mobilization at local and regional scales in NE Portugal. Keywords: forest management; maritime pine; forest modelling; knowledge transfer tool.

Spatial variation in the storages and age-related dynamics of forest carbon sequestration in different climate zones-evidence from black locust plantations on the Loess Plateau of China.

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Taijun Li

Full Text Available Knowledge about the long-term influences of climate change on the amount of potential carbon (C sequestration in forest ecosystems, including age-related dynamics, remains unclear. This study used two similar age-sequences of black locust forests (Robinia pseudoacacia L. in the semi-arid and semi-humid zones of China's Loess Plateau to assess the variation in C stocks and age-related dynamics. Our results demonstrated that black locust forests of the semi-humid zone stored significantly more C than did forests in the semi-arid zone, across the chronosequence (p < 0.001. The C carrying capacity of the plantations was measured at 166.4 Mg C ha-1 (1 Mg = 106 g in the semi-humid zone, while the semi-arid zone had a capacity of only 79.4 Mg C ha-1. Soil organic C (SOC increased continuously with stand age in the semi-arid zone (R2 = 0.84, p = 0.010. However, in the semi-humid zone, SOC declined sharply by 47.8% after the initial stage (5 to 10 y. The C stock in trees increased continuously with stand age in the semi-humid zone (R2 = 0.83, p = 0.011, yet in the semi-arid zone, it decreased dramatically from 43.0 Mg C ha-1 to 28.4 Mg C ha-1 during the old forest stage (38 to 56 y. The shift from being a net C sink to a net C source occurred at the initial stage in the semi-humid zone versus at the old forest stage in the semi-arid zone after reforestation. Surprisingly, with the exception of the initial and later stages (55 y, the patterns of C allocation among trees, soils, understory and litter were not statistically different between the two climate zones. Our results suggest that climate factors can alter the potential amount and age-related dynamics of forest C sequestration.

Indirect estimations and spatial variation in leaf area index of coniferous, deciduous and mixed forest stands in Forsmark and Laxemar

International Nuclear Information System (INIS)

Tagesson, Torbern

2006-12-01

Two sites in Sweden are investigated for a potential deep repository of the nuclear waste, the Laxemar investigation area (57 deg 5 min N, 16 deg 7 min E) and the Forsmark investigation area (60 deg 4 min N, 18 deg 2 min E). In the characterisation of these sites, development of site descriptive models is an important part. Leaves are the main surface were an exchange of matter and energy between the atmosphere and the biosphere takes place, and leaf area index (LAI) of the vegetation cover is an important variable correlated to a number of ecophysiological parameters and hereby an important parameter in ecosystem models. In the investigation areas, LAI of boreal and temperate ecosystems were therefore estimated indirectly through optical measurements using the LAI-2000 (LI-COR, Cambridge UK) and TRAC (Tracing Radiation and Architecture of Canopies). On average, measured maximum LAI was 3.40 in Laxemar and 3.43 in Forsmark; minimum LAI was 1.65 in Laxemar and 1.97 in Forsmark. Forest inventory data showed that LAI is positively correlated with basal area, stand height, stand volume and breast height tree diameter. For the coniferous stands, there was also a linearly negative relationship with age. In the Laxemar investigation area, there were no significant relationships for LAI with a satellite derived kNN (kNearest Neighbor) data set with stand height, stand volume and stand age. The kNN data set can therefore not be used to extrapolate measured LAI over the Laxemar investigation area. There were significant relationships between LAI and the normalized difference vegetation index (NDVI) for coniferous, deciduous and mixed forest stands in the Laxemar investigation area. A NDVI image could be used to extrapolate LAI over the entire investigation area. For the Forsmark investigation area, effective LAI for all stands were correlated to NDVI and this relationship could then be used for extrapolation. The effective LAI image was afterwards corrected for average

Indirect estimations and spatial variation in leaf area index of coniferous, deciduous and mixed forest stands in Forsmark and Laxemar

Energy Technology Data Exchange (ETDEWEB)

Tagesson, Torbern [Dept. of Physical Geography and Ecosystem Analysis, Lund Univ., Lund (Sweden)

2006-12-15

Two sites in Sweden are investigated for a potential deep repository of the nuclear waste, the Laxemar investigation area (57 deg 5 min N, 16 deg 7 min E) and the Forsmark investigation area (60 deg 4 min N, 18 deg 2 min E). In the characterisation of these sites, development of site descriptive models is an important part. Leaves are the main surface were an exchange of matter and energy between the atmosphere and the biosphere takes place, and leaf area index (LAI) of the vegetation cover is an important variable correlated to a number of ecophysiological parameters and hereby an important parameter in ecosystem models. In the investigation areas, LAI of boreal and temperate ecosystems were therefore estimated indirectly through optical measurements using the LAI-2000 (LI-COR, Cambridge UK) and TRAC (Tracing Radiation and Architecture of Canopies). On average, measured maximum LAI was 3.40 in Laxemar and 3.43 in Forsmark; minimum LAI was 1.65 in Laxemar and 1.97 in Forsmark. Forest inventory data showed that LAI is positively correlated with basal area, stand height, stand volume and breast height tree diameter. For the coniferous stands, there was also a linearly negative relationship with age. In the Laxemar investigation area, there were no significant relationships for LAI with a satellite derived kNN (kNearest Neighbor) data set with stand height, stand volume and stand age. The kNN data set can therefore not be used to extrapolate measured LAI over the Laxemar investigation area. There were significant relationships between LAI and the normalized difference vegetation index (NDVI) for coniferous, deciduous and mixed forest stands in the Laxemar investigation area. A NDVI image could be used to extrapolate LAI over the entire investigation area. For the Forsmark investigation area, effective LAI for all stands were correlated to NDVI and this relationship could then be used for extrapolation. The effective LAI image was afterwards corrected for average

Mercury concentrations and pools in four adjacent coniferous and deciduous upland forests in Beijing, China

Science.gov (United States)

Zhou, Jun; Wang, Zhangwei; Zhang, Xiaoshan; Gao, Yu

2017-05-01

Understanding of forest mercury (Hg) pools is important for quantifying the global atmospheric Hg removal. We studied gaseous elemental Hg (GEM) concentrations, litterfall Hg depositions, and pool sizes in four adjacent stands at Mount Dongling to assess Hg dynamics in the forested catchment and the potential of Hg release during wildfires. The average GEM concentration was 2.5 ± 0.5 ng m-3, about 1.5 times of the background levels in the Northern Hemisphere. In all four stands, Hg concentrations increase in the following order: bole wood mineral soil litter < Oe soil < Oa organic soil. The Hg pools of aboveground biomass were comparable in the forests of larch, oak, and Chinese pine, which were much greater than that of mixed broadleaf stands due to lower biomass. The total Hg pools in ecosystems were similar in the four stands, because of the comparable Hg pool in the soil horizons (0-40 cm), which accounted for over 97% of the total ecosystem Hg storage in the four stands. Although Hg pools of the forest ecosystem in north China were comparable to North America and North Europe, Hg storage in forests constituted a high threat for large Hg emission pulses to the atmosphere by wildfires. The potential Hg emissions from the combustion at the four stands were ranged from 0.675 to 1.696 mg m-2.

Effects of disturbance and climate change on ecosystem performance in the Yukon River Basin boreal forest

Science.gov (United States)

Wylie, Bruce K.; Rigge, Matthew B.; Brisco, Brian; Mrnaghan, Kevin; Rover, Jennifer R.; Long, Jordan

2014-01-01

A warming climate influences boreal forest productivity, dynamics, and disturbance regimes. We used ecosystem models and 250 m satellite Normalized Difference Vegetation Index (NDVI) data averaged over the growing season (GSN) to model current, and estimate future, ecosystem performance. We modeled Expected Ecosystem Performance (EEP), or anticipated productivity, in undisturbed stands over the 2000–2008 period from a variety of abiotic data sources, using a rule-based piecewise regression tree. The EEP model was applied to a future climate ensemble A1B projection to quantify expected changes to mature boreal forest performance. Ecosystem Performance Anomalies (EPA), were identified as the residuals of the EEP and GSN relationship and represent performance departures from expected performance conditions. These performance data were used to monitor successional events following fire. Results suggested that maximum EPA occurs 30–40 years following fire, and deciduous stands generally have higher EPA than coniferous stands. Mean undisturbed EEP is projected to increase 5.6% by 2040 and 8.7% by 2070, suggesting an increased deciduous component in boreal forests. Our results contribute to the understanding of boreal forest successional dynamics and its response to climate change. This information enables informed decisions to prepare for, and adapt to, climate change in the Yukon River Basin forest.

Integrating Landsat-derived disturbance maps with FIA inventory data: Applications for state-Level forest resource assessments

Science.gov (United States)

Sonja Oswalt; Chengquan Huang; Hua Shi; James Vogelmann; Zhiliang Zhu; Samuel N. Goward; John Coulston

2009-01-01

Landsat images have been widely used for assessing forest characteristics and dynamics. Recently, significant progress has been made towards indepth exploration of the rich Landsat archive kept by the U.S. Geological Survey to improve our under standing of forest disturbance and recovery processes. In this study, we used Landsat images to map forest disturbances at...

Height development of shade-tolerant conifer saplings in multiaged Acadian forest stands

Science.gov (United States)

Andrew R. Moores; Robert S. Seymour; Laura S. Kenefic

2007-01-01

Understory growth dynamics of northern conifer species were studied in four stands managed under multiaged silvicultural systems in eastern Maine. Height growth of Picea rubens Sarg., Abies balsamea (L.) Mill., and Tsuga canadensis (L.) Carr. saplings between 0.5 and 6.0 m in height was related to the proportion...

Dynamics of combined forest damage risks for 21st century (SRES A1B, B1)

Science.gov (United States)

Panferov, Oleg; Merklein, Johannes; Sogachev, Andrey; Junghans, Udo; Ahrends, Bernd

2010-05-01

of forest ecosystems, wind loading on trees and biotic damage for several tree species and typical soil types. The damage risks a certain forest stand at a given soil results from daily combinations of air and soil temperatures, soil water characteristics, static and gust wind loads on trees with dynamic LAI and of soil texture. Some damaged stands show higher vulnerability and thus - positive feedbacks to climate forcing (Vygodskaya et al., 2007). Therefore, changes of microclimate in remaining stands after changes in forest structure are taken into account. Model output is aggregated to 30-years periods and compared to "present conditions" of 1981-2010. The results show considerable increment of both biotic and abiotic risks towards 2100 relatively to "present" caused by weak changes in precipitation and wind patterns and strong increase of mean air temperature and soil temperatures. It is shown, e.g. that the wind- damage-induced changes of structure and microclimate provide a positive feedback i.e. - increase the probability of the next damage event. The study was financed by BMBF within the frames of joint project "Decision Support System - Forest and Climate Change" (DSS-WuK) and by Grant of Ministry for Science and Culture of Lower Saxony "KLIFF". We gratefully acknowledge this support.

Digital data collection in forest dynamics plots

Science.gov (United States)

Faith Inman-Narahari; Christian Giardina; Rebecca Ostertag; Susan Cordell; Lawren Sack

2010-01-01

Summary 1. Computers are widely used in all aspects of research but their application to in-field data collection for forest plots has rarely been evaluated. 2. We developed digital data collection methods using ESRI mapping software and ruggedized field computers to map and measure ~30 000 trees in two 4-ha forest dynamics plots in wet and dry...

Biological and Energy Productivity of Natural Spruce Forests in the Ukrainian Carpathians

Directory of Open Access Journals (Sweden)

R. D. Vasilishyn

2014-10-01

Full Text Available The modern practice of forestry production in Ukraine, which is in the process of implementing the conceptual changes in forest management and harmonization of its basic approaches to the basics of sustainable development, requires a significant expansion of the current regulatory and informational tools used to assess the ecological functions of forests. For this purpose, during the 2012–2014, as part of an international project GESAPU, models and tables of bioproductivity for forest tree species in Ukraine were completed. The article presents the results of modeling the dynamics of the conversion coefficients for the main components of phytomass of modal natural spruce forests of the Carpathian region of Ukraine based on information from 32 plots in the database of «Forest Phytomass of Ukraine». According to the state forest accounting of Ukraine as of January 1, 2011, the spruce forests in the Ukrainian Carpathians cover an area of 426.2 thousand ha, 45 % of which are spruce of natural origin. To evaluate the productivity of modal dynamics of pure and mixed spruce stands, the study developed models of the stock and overall productivity, derived by Bertalanffy growth function. On the basis of these models, normative reference tables of biological productivity of natural modal spruce forests of the Ukrainian Carpathians were developed. To successfully meet the challenges of evaluating the energy possibilities of forestry of Ukraine, the study used tables of energetic productivity of investigated stands. Built on the basis of the tables of bioproductivity, they reflect the dynamic processes of energy storage in the phytomass components and can be used in forest management to predict volumes of energetic woods.

Disturbance history and stand dynamics in secondary and old-growth forests of the Southern Appalachian Mountains, USA

Science.gov (United States)

Sarah M. Butler; Alan S. White; Katherine J. Elliott; Robert S Seymour

2014-01-01

BUTLER, S. M. (Family Forest Research Center, University of Massachusetts, Amherst, MA 01003), A. S. WHITE (School of Forest Resources, University of Maine, Orono, ME 04469-5755), K. J. ELLIOTT (Coweeta Hydrologic Laboratory, Center for Forest Watershed Science, Southern Research Station, USDA Forest Service, Otto, NC 28763) AND R. S. SEYMOUR (School of Forest...

The carbon fluxes in different successional stages: modelling the dynamics of tropical montane forests in South Ecuador

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Sebastian Paulick

2017-05-01

Full Text Available Background Tropical forests play an important role in the global carbon (C cycle. However, tropical montane forests have been studied less than tropical lowland forests, and their role in carbon storage is not well understood. Montane forests are highly endangered due to logging, land-use and climate change. Our objective was to analyse how the carbon balance changes during forest succession. Methods In this study, we used a method to estimate local carbon balances that combined forest inventory data with process-based forest models. We utilised such a forest model to study the carbon balance of a tropical montane forest in South Ecuador, comparing two topographical slope positions (ravines and lower slopes vs upper slopes and ridges. Results The simulation results showed that the forest acts as a carbon sink with a maximum net ecosystem exchange (NEE of 9.3 Mg C∙(ha∙yr−1 during its early successional stage (0–100 years. In the late successional stage, the simulated NEE fluctuated around zero and had a variation of 0.77 Mg C∙(ha∙yr –1. The simulated variability of the NEE was within the range of the field data. We discovered several forest attributes (e.g., basal area or the relative amount of pioneer trees that can serve as predictors for NEE for young forest stands (0–100 years but not for those in the late successional stage (500–1,000 years. In case of young forest stands these correlations are high, especially between stand basal area and NEE. Conclusion In this study, we used an Ecuadorian study site as an example of how to successfully link a forest model with forest inventory data, for estimating stem-diameter distributions, biomass and aboveground net primary productivity. To conclude, this study shows that process-based forest models can be used to investigate the carbon balance of tropical montane forests. With this model it is possible to find hidden relationships between forest attributes and forest carbon fluxes

Distribution and dynamics of hayscented fern following stand harvest

Science.gov (United States)

Songlin Fei; Peter J. Gould; Melanie J. Kaeser; Kim C. Steiner

2008-01-01

The distribution and dynamics of hayscented fern were examined as part of a large-scale study of oak regeneration in Pennsylvania. The study included 69 stands covering 3,333 acres in two physiographic provinces. Hayscented fern was more widely distributed and occurred at higher densities in the Allegheny Plateau physiographic provinces versus the Ridge and Valley...

Opposing effects of fire severity on climate feedbacks in Siberian larch forests

Science.gov (United States)

Loranty, M. M.; Alexander, H. D.; Natali, S.; Kropp, H.; Mack, M. C.; Bunn, A. G.; Davydov, S. P.; Erb, A.; Kholodov, A. L.; Schaaf, C.; Wang, Z.; Zimov, N.; Zimov, S. A.

2017-12-01

Boreal larch forests in northeastern Siberia comprise nearly 25% of the continuous permafrost zone. Structural and functional changes in these ecosystems will have important climate feedbacks at regional and global scales. Like boreal ecosystems in North America, fire is an important determinant of landscape scale forest distribution, and fire regimes are intensifying as climate warms. In Siberian larch forests are dominated by a single tree species, and there is evidence that fire severity influences post-fire forest density via impacts on seedling establishment. The extent to which these effects occur, or persist, and the associated climate feedbacks are not well quantified. In this study we use forest stand inventories, in situ observations, and satellite remote sensing to examine: 1) variation in forest density within and between fire scars, and 2) changes in land surface albedo and active layer dynamics associated with forest density variation. At the landscape scale we observed declines in Landsat derived albedo as forests recovered in the first several decades after fire, though canopy cover varied widely within and between individual fire scars. Within an individual mid-successional fire scar ( 75 years) we observed canopy cover ranging from 15-90% with correspondingly large ranges of albedo during periods of snow cover, and relatively small differences in albedo during the growing season. We found an inverse relationship between canopy density and soil temperature within this fire scar; high-density low-albedo stands had cooler soils and shallower active layers, while low-density stands had warmer soils and deeper active layers. Intensive energy balance measurements at a high- and low- density site show that canopy cover alters the magnitude and timing of ground heat fluxes that affect active layer properties. Our results show that fire impacts on stand structure in Siberian larch forests affect land surface albedo and active layer dynamics in ways that

Water cycle and salinity dynamics in the mangrove forests of Europa and Juan de Nova Islands, southwest Indian Ocean.

Science.gov (United States)

Lambs, Luc; Mangion, Perrine; Mougin, Eric; Fromard, François

2016-01-30

The functioning of mangrove forests found on small coralline islands is characterized by limited freshwater inputs. Here, we present data on the water cycling of such systems located on Europa and Juan de Nova Islands, Mozambique Channel. In order to better understand the water cycle and mangrove growth conditions, we have analysed the hydrological and salinity dynamics of the systems by gauge pressure and isotopic tracing (δ18O and δ2H values). Both islands have important seawater intrusion as measured by the water level change and the high salinities in the karstic ponds. Europa Island displays higher salinity stress, with its inner lagoon, but presents a pluri-specific mangrove species formation ranging from shrub to forest stands. No freshwater signal could be detected around the mangrove trees. On Juan de Nova Island, the presence of sand and detrital sediment allows the storage of some amount of rainfall to form a brackish groundwater. The mangrove surface area is very limited with only small mono-specific stands being present in karstic depression. On the drier Europa Island, the salinity of all the water points is equal to or higher than that of the seawater, and on Juan de Nova the groundwater salinity is lower (5 to 20 PSU). This preliminary study shows that the karstic pothole mangroves exist due to the sea connection through the fractured coral and the high tidal dynamics.

Modelling forest dynamics along climate gradients in Bolivia

NARCIS (Netherlands)

Seiler, C.; Hutjes, R.W.A.; Kruijt, B.; Quispe, J.; Añez, S.; Arora, V.K.; Melton, J.R.; Hickler, T.; Kabat, P.

2014-01-01

Dynamic vegetation models have been used to assess the resilience of tropical forests to climate change, but the global application of these modeling experiments often misrepresents carbon dynamics at a regional level, limiting the validity of future projections. Here a dynamic vegetation model

Rehabilitation of Understocked Loblolly-Shortleaf Pine Stands - I. Recently Cutover Natural Stands

Science.gov (United States)

James B. Baker; Michael G. Shelton

1998-01-01

A 1988 USDA Forest Service report indicated that 22% (40 million ac) of the commercial timberland in the South was understocked (less than 60% stocking) with desirable tree species for timber production (USDA Forest Service 1988). The understocked stands are usually the result of past har-vesting practices, natural catastrophes, or regeneration fail-ures. Understocked...

Foliar free polyamine and inorganic ion content in relation to soil and soil solution chemistry in two fertilized forest stands at the Harvard Forest, Massachusetts

Science.gov (United States)

Rakesh Minocha; Stephanie Long; Alison H. Magill; John Aber; William H. McDowell

2000-01-01

Polyamines (putrescine, spermidine, and spermine) are low molecular weight, open-chained, organic polycations which are found in all organisms and have been linked with stress responses in plants. The objectives of our study were to investigate the effects of chronic N additions to pine and hardwood stands at Harvard Forest, Petersham, MA on foliar polyamine and...

Can Forest Transformation Help Reducing Floods in Forested Watersheds?

DEFF Research Database (Denmark)

Wahl, Niels Arne; Wöllecke, B.; Benz, O.

2005-01-01

of the management practice of forest transformation in forested areas on soil hydraulic properties is presented and discussed as a means of preventing such disasters at a reasonable cost and during a foreseeable period. Investigations were carried out in northeastern Germany on forest stands differing in tree...... populations and stand structure. It was found that infiltration capacity and hydraulic conductivity K exhibit overall low values nevertheless the tree species. This finding appears to be related to water repellency, the predominating texture, and a poor macroporosity. During the different stages of forest...

Decadal-scale ecosystem memory reveals interactive effects of drought and insect defoliation on boreal forest productivity

Science.gov (United States)

Itter, M.; D'Orangeville, L.; Dawson, A.; Kneeshaw, D.; Finley, A. O.

2017-12-01

Drought and insect defoliation have lasting impacts on the dynamics of the boreal forest. Impacts are expected to worsen under global climate change as hotter, drier conditions forecast for much of the boreal increase the frequency and severity of drought and defoliation events. Contemporary ecological theory predicts physiological feedbacks in tree responses to drought and defoliation amplify impacts potentially causing large-scale productivity losses and forest mortality. Quantifying the interactive impacts of drought and insect defoliation on regional forest health is difficult given delayed and persistent responses to disturbance events. We developed a Bayesian hierarchical model to estimate forest growth responses to interactions between drought and insect defoliation by species and size class. Delayed and persistent responses to past drought and defoliation were quantified using empirical memory functions allowing for improved detection of interactions. The model was applied to tree-ring data from stands in Western (Alberta) and Eastern (Québec) regions of the Canadian boreal forest with different species compositions, disturbance regimes, and regional climates. Western stands experience chronic water deficit and forest tent caterpillar (FTC) defoliation; Eastern stands experience irregular water deficit and spruce budworm (SBW) defoliation. Ecosystem memory to past water deficit peaked in the year previous to growth and decayed to zero within 5 (West) to 8 (East) years; memory to past defoliation ranged from 8 (West) to 12 (East) years. The drier regional climate and faster FTC defoliation dynamics (compared to SBW) likely contribute to shorter ecosystem memory in the West. Drought and defoliation had the largest negative impact on large-diameter, host tree growth. Surprisingly, a positive interaction was observed between drought and defoliation for large-diameter, non-host trees likely due to reduced stand-level competition for water. Results highlight the

Volume and weight characteristics of a typical Douglas-fir/ western larch stand, Coram Experimental Forest, Montana

Science.gov (United States)

Robert E. Benson; Joyce A. Schlieter

1980-01-01

An over-mature Douglas-fir/western larch stand on the Coram Experimental Forest in Montana averaged about 7,300 ft3/acre (511 rn3/ha) of wood over 3 inches (7.62 cm) in diameter, and an additional 57 tons/acre (128/ha) of fine material, before harvest. After logging, using three different cutting methods and four different levels of utilization, wood residues ranged...

Species Composition, Tree Quality and Wood Properties of Southern Pine Stands Under Ecosystemm Management on National Forests in the Peidmont and Coastal Plain

Science.gov (United States)

Alexander Clark; James W. McMinn

1999-01-01

National Forests in the United States are under sustainable ecosystem management to conserve biodiversity, achieve sustainable conditions and improve the balance among forest values. This paper reports on a study established to identify the implications of ecosystem management strategies on natural stands in the Piedmont and Coastal Plain. The impact of partial...

Fine root dynamics in moso bamboo and Japanese cedar forest by scanner method in central Taiwan

Science.gov (United States)

Chen, Zhi-Wei; Lin, Po-Hsuan; Kume, Tomonori

2017-04-01

Phyllostachys pubescens is one of the most important economic plant in the world. Phyllostachys pubescens originates from China and it had been introduced to neighbor countries about three hundred ago due to its economic value. But substantial bamboo forests were abandoned due to declines in demand. These unmanaged bamboo forests have been expanding to adjacent original forests in northern Taiwan. This vegetation alternation may not only decrease the local biodiversity but also affect the carbon cycle. Fine roots are responsible for water and nutrients acquisition and forming the most active part of the whole root system. The characteristics of fine roots are non-woody, small diameter and short lifespan. When roots keep producing new roots and replacing old roots, carbon and nutrients was transported into soil. Consequently, fine root production is one of the important component to understand the below-ground carbon cycle. However, there is few studies about fine root production in moso bamboo forests. We still lack effective method to obtain quantitative and objective data in Taiwan. It severely limits us to understand the below-ground carbon dynamics there. Minirhizotrons method has been used to investigate fine root dynamics by inserting transparent tubes into soil and by comparing changes in root length in images taken by micro-camera. But this method has some shortcomings; i.e. Most of image analysis are conducted manually and time-consuming. And it is difficult to estimate the stand level fine root production from small observation view. A new method "scanner method", which collect A4-size image (bigger than minirhizotrons) can overcome some parts of the shortcoming of minirhizotrons. The transparent acrylic box with A4-box view is inserted into soil and the interface between soil and box is scanned by commercial scanner. We can monitor the total projected root area, growth and decomposition separately by series of images. The primary objective of this study

The impacts of increasing drought on forest dynamics, structure, and biodiversity in the United States

Science.gov (United States)

James S. Clark; Louis Iverson; Christopher W. Woodall; Craig D. Allen; David M. Bell; Don C. Bragg; Anthony W. D' Amato; Frank W. Davis; Michelle H. Hersh; Ines Ibanez; Stephen T. Jackson; Stephen Matthews; Neil Pederson; Matthew Peters; Mark W. Schwartz; Kristen M. Waring; Niklaus E. Zimmermann

2016-01-01

We synthesize insights from current understanding of drought impacts at stand-to-biogeographic scales, including management options, and we identify challenges to be addressed with new research. Large stand-level shifts underway in western forests already are showing the importance of interactions involving drought, insects, and fire. Diebacks, changes in composition...

The role of strategic forest inventories in aiding land management decision-making: Examples from the U.S

Science.gov (United States)

W. Keith Moser; Renate Bush; John D. Shaw; Mark H. Hansen; Mark D. Nelson

2010-01-01

A major challenge for today’s resource managers is the linking of standand landscape-scale dynamics. The U.S. Forest Service has made major investments in programs at both the stand- (national forest project) and landscape/regional (Forest Inventory and Analysis [FIA] program) levels. FIA produces the only comprehensive and consistent statistical information on the...

Estimation of crown biomass of Pinus pinaster stands and shrubland above-ground biomass using forest inventory data, remotely sensed imagery and spatial prediction models

Science.gov (United States)

H. Viana; J. Aranha; D. Lopes; Warren B. Cohen

2012-01-01

Spatially crown biomass of Pinus pinaster stands and shrubland above-ground biomass (AGB) estimation was carried-out in a region located in Centre-North Portugal, by means of different approaches including forest inventory data, remotely sensed imagery and spatial prediction models. Two cover types (pine stands and shrubland) were inventoried and...

Impact of Nitrogen Fertilization on Forest Carbon Sequestration and Water Loss in a Chronosequence of Three Douglas-Fir Stands in the Pacific Northwest

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Xianming Dou

2015-05-01

Full Text Available To examine the effect of nitrogen (N fertilization on forest carbon (C sequestration and water loss, we used an artificial neural network model to estimate C fluxes and evapotranspiration (ET in response to N fertilization during four post-fertilization years in a Pacific Northwest chronosequence of three Douglas-fir stands aged 61, 22 and 10 years old in 2010 (DF49, HDF88 and HDF00, respectively. Results showed that N fertilization increased gross primary productivity (GPP for all three sites in all four years with the largest absolute increase at HDF00 followed by HDF88. Ecosystem respiration increased in all four years at HDF00, but decreased over the last three years at HDF88 and over all four years at DF49. As a result, fertilization increased the net ecosystem productivity of all three stands with the largest increase at HDF88, followed by DF49. Fertilization had no discernible effect on ET in any of the stands. Consequently, fertilization increased water use efficiency (WUE in all four post-fertilization years at all three sites and also increased light use efficiency (LUE of all the stands, especially HDF00. Our results suggest that the effects of fertilization on forest C sequestration and water loss may be associated with stand age and fertilization; the two younger stands appeared to be more efficient than the older stand with respect to GPP, WUE and LUE.

Application of GIS to Empirical Windthrow Risk Model in Mountain Forested Landscapes

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Lukas Krejci

2018-02-01

Full Text Available Norway spruce dominates mountain forests in Europe. Natural variations in the mountainous coniferous forests are strongly influenced by all the main components of forest and landscape dynamics: species diversity, the structure of forest stands, nutrient cycling, carbon storage, and other ecosystem services. This paper deals with an empirical windthrow risk model based on the integration of logistic regression into GIS to assess forest vulnerability to wind-disturbance in the mountain spruce forests of Šumava National Park (Czech Republic. It is an area where forest management has been the focus of international discussions by conservationists, forest managers, and stakeholders. The authors developed the empirical windthrow risk model, which involves designing an optimized data structure containing dependent and independent variables entering logistic regression. The results from the model, visualized in the form of map outputs, outline the probability of risk to forest stands from wind in the examined territory of the national park. Such an application of the empirical windthrow risk model could be used as a decision support tool for the mountain spruce forests in a study area. Future development of these models could be useful for other protected European mountain forests dominated by Norway spruce.

Trends in dynamics of forest upper boundary in high mountains of northern Baikal area

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V. I. Voronin

2016-08-01

Full Text Available Studies of spatial-temporal variability of the upper boundary of the forest on the north-western coast of Lake Baikal (Baikal and Upper Angara Ridges are performed on the base of the analysis of forests renewal processes and of the dynamics of larch radial increment in the ecotone of the forest upper boundary and out of it. The presence of a large amount of well-developed uplands and circuses with considerable heights drops in the structure of mountain system favours formation of interrupted boundary between forest and subgoltsy belt. The timber stand of the upper forest boundary in the studied area is represented by Daurian larch. Three tree-ring chronologies of larch are obtained. The longest chronology is obtained for mountain taiga belt of Baikal Ridge and is as long as 460 years. Since 1980ies, a sustainable trend of increase of radial trees growth is observed. It is observed the most distinctly in trees of the upper forest boundary on the Baikal Ridge. There is advancing of trees species into subgoltsy belt and into mountain tundra, which depends, respectively, on slopes heights, exposition and tilting, on sites of growth of concrete cenoses. Modern peculiarity of the vegetation of the studied area is presence of abundant viable larch undergrowth (from 2–3 to 25 y.o. and fir in the ecotone of upper forest boundary and in subgoltsy belt, as well as appearing of single specimens of spruce. Main undergrowth mass (2/3 is presented by trees aged in average 15–25 y.o., i.e., they appeared in late 1980ies. Due to increase of snow cover thickness in winter, the trees young growth obtained great protection from freezing resulting in the increase of ability of young growth to live up to elder age.

Spectral Similarity and PRI Variations for a Boreal Forest Stand Using Multi-angular Airborne Imagery

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Vincent Markiet

2017-09-01

Full Text Available The photochemical reflectance index (PRI is a proxy for light use efficiency (LUE, and is used in remote sensing to measure plant stress and photosynthetic downregulation in plant canopies. It is known to depend on local light conditions within a canopy indicating non-photosynthetic quenching of incident radiation. Additionally, when measured from a distance, canopy PRI depends on shadow fraction—the fraction of shaded foliage in the instantaneous field of view of the sensor—due to observation geometry. Our aim is to quantify the extent to which sunlit fraction alone can describe variations in PRI so that it would be possible to correct for its variation and identify other possible factors affecting the PRI–sunlit fraction relationship. We used a high spatial and spectral resolution Aisa Eagle airborne imaging spectrometer above a boreal Scots pine site in Finland (Hyytiälä forest research station, 61°50′N, 24°17′E, with the sensor looking in nadir and tilted (off-nadir directions. The spectral resolution of the data was 4.6 nm, and the spatial resolution was 0.6 m. We compared the PRI for three different scatter angles ( β = 19 ° , 55 ° and 76 °, defined as the angle between sensor and solar directions at the forest stand level, and observed a small (0.006 but statistically significant (p < 0.01 difference in stand PRI. We found that stand mean PRI was not a direct function of sunlit fraction. However, for each scatter angle separately, we found a clear non-linear relationship between PRI and sunlit fraction. The relationship was systematic and had a similar shape for all of the scatter angles. As the PRI–sunlit fraction curves for the different scatter angles were shifted with respect to each other, no universal curve could be found causing the observed independence of canopy PRI from the average sunlit fraction of each view direction. We found the shifts of the curves to be related to a leaf structural effect on canopy

Contributions of secondary forest and nitrogen dynamics to terrestrial carbon uptake

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X. Yang

2010-10-01

Full Text Available We use a terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM to investigate the impacts of nitrogen dynamics on regrowing secondary forests over the 20th century. We further examine what the impacts of nitrogen deposition and land use change history are on terrestrial carbon uptake since preindustrial time. Our results suggest that global total net land use emissions for the 1990s associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher than if secondary forest regrowth is considered. Results also show that without considering the nitrogen dynamics and deposition, the estimated global total secondary forest sink for the 1990s is 0.90 GtC/yr or about 0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting nutrient in the intact primary forests in tropical regions, our study suggests that nitrogen becomes a limiting nutrient for regrowing secondary forests of the tropical regions, in particular Latin America and Tropical Africa. This is because land use change activities, especially wood harvest, removes large amounts of nitrogen from the system when slash is burnt or wood is removed for harvest. However, our model results show that carbon uptake is enhanced in the tropical secondary forests of the Indian region. We argue that this may be due to enhanced nitrogen mineralization and increased nitrogen availability following land use change in the Indian tropical forest ecosystems. Results also demonstrate that there is a significant amount of carbon accumulating in the Northern Hemisphere where most land use changes and forest regrowth has occurred in recent decades

Modeling forest dynamics along climate gradients in Bolivia

Science.gov (United States)

Seiler, C.; Hutjes, R. W. A.; Kruijt, B.; Quispe, J.; Añez, S.; Arora, V. K.; Melton, J. R.; Hickler, T.; Kabat, P.

2014-05-01

Dynamic vegetation models have been used to assess the resilience of tropical forests to climate change, but the global application of these modeling experiments often misrepresents carbon dynamics at a regional level, limiting the validity of future projections. Here a dynamic vegetation model (Lund Potsdam Jena General Ecosystem Simulator) was adapted to simulate present-day potential vegetation as a baseline for climate change impact assessments in the evergreen and deciduous forests of Bolivia. Results were compared to biomass measurements (819 plots) and remote sensing data. Using regional parameter values for allometric relations, specific leaf area, wood density, and disturbance interval, a realistic transition from the evergreen Amazon to the deciduous dry forest was simulated. This transition coincided with threshold values for precipitation (1400 mm yr-1) and water deficit (i.e., potential evapotranspiration minus precipitation) (-830 mm yr-1), beyond which leaf abscission became a competitive advantage. Significant correlations were found between modeled and observed values of seasonal leaf abscission (R2 = 0.6, p days. Decreasing rainfall trends were simulated to reduce GPP in the Amazon. The current model setup provides a baseline for assessing the potential impacts of climate change in the transition zone from wet to dry tropical forests in Bolivia.

Test of four stand growth simulators for the northeastern United States

Science.gov (United States)

Thomas M. Schuler; David A. Marquis; Richard L. Ernst; Brian T. Simpson; Brian T. Simpson

1993-01-01

Evaluates SILVAH, FIBER, NE-TWIGS, and OAKSIM, simulators commonly used in the northeastern United States, by comparing predicted stand development with actual stand development records for periods ranging from 15 to 50 years. Results varied with stand parameter, forest type, projection length, and geographic area. Except in the spruce-fir forest type where FIBER...

A review of malaria transmission dynamics in forest ecosystems

Science.gov (United States)

2014-01-01

Malaria continues to be a major health problem in more than 100 endemic countries located primarily in tropical and sub-tropical regions around the world. Malaria transmission is a dynamic process and involves many interlinked factors, from uncontrollable natural environmental conditions to man-made disturbances to nature. Almost half of the population at risk of malaria lives in forest areas. Forests are hot beds of malaria transmission as they provide conditions such as vegetation cover, temperature, rainfall and humidity conditions that are conducive to distribution and survival of malaria vectors. Forests often lack infrastructure and harbor tribes with distinct genetic traits, socio-cultural beliefs and practices that greatly influence malaria transmission dynamics. Here we summarize the various topographical, entomological, parasitological, human ecological and socio-economic factors, which are crucial and shape malaria transmission in forested areas. An in-depth understanding and synthesis of the intricate relationship of these parameters in achieving better malaria control in various types of forest ecosystems is emphasized. PMID:24912923

Forest structure and light regimes following moderate wind storms: implications for multi-cohort management.

Science.gov (United States)

Hanson, Jacob J; Lorimer, Craig G

2007-07-01

Moderate-severity disturbances appear to be common throughout much of North America, but they have received relatively little detailed study compared to catastrophic disturbances and small gap dynamics. In this study, we examined the immediate impact of moderate-intensity wind storms on stand structure, opening sizes, and light regimes in three hemlock-hardwood forests of northeastern Wisconsin. These were compared to three stands managed by single-tree and group selection, the predominant forest management system for northern hardwoods in the region. Wind storms removed an average of 41% of the stand basal area, compared to 27% removed by uneven-aged harvests, but both disturbances removed trees from a wide range of size classes. The removal of nearly half of the large trees by wind in two old-growth stands caused partial retrogression to mature forest structure, which has been hypothesized to be a major disturbance pathway in the region. Wind storms resulted in residual stand conditions that were much more heterogeneous than in managed stands. Gap sizes ranged from less than 10 m2 up to 5000 m2 in wind-disturbed stands, whereas the largest opening observed in managed stands was only 200 m2. Wind-disturbed stands had, on average, double the available solar radiation at the forest floor compared to managed stands. Solar radiation levels were also more heterogeneous in wind-disturbed stands, with six times more variability at small scales (0.1225 ha) and 15 times more variability at the whole-stand level. Modification of uneven-aged management regimes to include occasional harvests of variable intensity and spatial pattern may help avoid the decline in species diversity that tends to occur after many decades of conventional uneven-aged management. At the same time, a multi-cohort system with these properties would retain a high degree of average crown cover, promote structural heterogeneity typical of old-growth forests, and maintain dominance by late

Evaluating the impact of abrupt changes in forest policy and management practices on landscape dynamics: analysis of a Landsat image time series in the Atlantic Northern Forest.

Science.gov (United States)

Legaard, Kasey R; Sader, Steven A; Simons-Legaard, Erin M

2015-01-01

Sustainable forest management is based on functional relationships between management actions, landscape conditions, and forest values. Changes in management practices make it fundamentally more difficult to study these relationships because the impacts of current practices are difficult to disentangle from the persistent influences of past practices. Within the Atlantic Northern Forest of Maine, U.S.A., forest policy and management practices changed abruptly in the early 1990s. During the 1970s-1980s, a severe insect outbreak stimulated salvage clearcutting of large contiguous tracts of spruce-fir forest. Following clearcut regulation in 1991, management practices shifted abruptly to near complete dependence on partial harvesting. Using a time series of Landsat satellite imagery (1973-2010) we assessed cumulative landscape change caused by these very different management regimes. We modeled predominant temporal patterns of harvesting and segmented a large study area into groups of landscape units with similar harvest histories. Time series of landscape composition and configuration metrics averaged within groups revealed differences in landscape dynamics caused by differences in management history. In some groups (24% of landscape units), salvage caused rapid loss and subdivision of intact mature forest. Persistent landscape change was created by large salvage clearcuts (often averaging > 100 ha) and conversion of spruce-fir to deciduous and mixed forest. In groups that were little affected by salvage (56% of landscape units), contemporary partial harvesting caused loss and subdivision of intact mature forest at even greater rates. Patch shape complexity and edge density reached high levels even where cumulative harvest area was relatively low. Contemporary practices introduced more numerous and much smaller patches of stand-replacing disturbance (typically averaging forest ecology.

Optimization Forest Thinning Measures for Carbon Budget in a Mixed Pine-Oak Stand of the Qingling Mountains, China: A Case Study

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Lin Hou

2016-11-01

Full Text Available Forest thinning is a silviculture treatment for sustainable forest management. It may promote growth of the remaining individuals by decreasing stand density, reducing competition, and increasing light and nutrient availability to increase carbon sequestration in the forest ecosystem. However, the action also increases carbon loss simultaneously by reducing carbon and other nutrient inputs as well as exacerbating soil CO2 efflux. To achieve a maximum forest carbon budget, the central composite design with two independent variables (thinning intensity and thinning residual removal rate was explored in a natural pine-oak mixed stand in the Qinling Mountains, China. The net primary productivity of living trees was estimated and soil CO2 efflux was stimulated by the Yasso07 model. Based on two years observation, the preliminary results indicated the following. Evidently chemical compounds of the litter of the tree species affected soil CO2 efflux stimulation. The thinning residual removal rate had a larger effect than thinning intensity on the net ecosystem productivity. When the selective thinning intensity and residual removal rate was 12.59% and 66.62% concurrently, the net ecosystem productivity reached its maximum 53.93 t·ha−1·year−1. The lower thinning intensity and higher thinning residual removal rated benefited the net ecosystem productivity.

Identifying forest patterns from space to explore dynamics across the circumpolar boreal

Science.gov (United States)

Montesano, P. M.; Neigh, C. S. R.; Feng, M.; Channan, S.; Sexton, J. O.; Wagner, W.; Wooten, M.; Poulter, B.; Wang, L.

2017-12-01

A variety of forest patterns are the result of interactions between broad-scale climate and local-scale site factors and history across the northernmost portion of the circumpolar boreal. Patterns of forest extent, height, and cover help describe forest structure transitions that influence future and reflect past dynamics. Coarse spaceborne observations lack structural detail at forest transitions, which inhibits understanding of these dynamics. We highlight: (1) the use of sub-meter spaceborne stereogrammetry for deriving structure estimates in boreal forests; (2) its potential to complement other spaceborne estimates of forest structure at critical scales; and (3) the potential of these sub-meter and other Landsat-derived structure estimates for improving understanding of broad-scale boreal dynamics such as carbon flux and albedo, capturing the spatial variability of the boreal-tundra biome boundary, and assessing its potential for change.

Carbon Storage and Allocation Pattern in Plant Biomass among Different Forest Plantation Stands in Guangdong, China

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Yuanqi Chen

2015-03-01

Full Text Available In order to understand how carbon storage and allocation patterns vary among plantation types, we estimated carbon allocation between above- and below-ground compartments in four subtropical plantations and a naturally recovered shrubland (as a control. Results indicated that the carbon storage and allocation pattern varied greatly among forest types and was highly dependent on specific traits of trees and understory vegetation. The fast-growing species, such as Eucalyptus urophylla, accumulated more carbon in plant biomass. The biomass carbon was about 1.9- and 2.2-times greater than the 10-species mixed plantation and Castanopsis hystrix plantations, respectively. Meanwhile, the plantations sequestered 1.5- to 3-times more carbon in biomass than naturally recovered shrubland. The carbon allocation pattern between above- and below-ground compartments also varied with plantation type and stand age. The ratio of tree root carbon to tree aboveground carbon decreased with stand age for Eucalyptus urophylla and the 10-species mixed plantation. In contrast, the ratio increased for Acacia crassicarpa. Our data suggested that planting the fast-growing species in the degraded land of subtropical China was an effective choice in terms of carbon sequestration. The information about carbon allocation patterns was also valuable for decision making in sustainable forest management and climate change mitigation.

Does nitrogen and sulfur deposition affect forest productivity?

Science.gov (United States)

Brittany A. Johnson; Kathryn B. Piatek; Mary Beth Adams; John R. Brooks

2010-01-01

We studied the effects of atmospheric nitrogen and sulfur deposition on forest productivity in a 10-year-old, aggrading forest stand at the Fernow Experimental Forest in Tucker County, WV. Forest productivity was expressed as total aboveground wood biomass, which included stem and branch weight of standing live trees. Ten years after stand regeneration and treatment...

Squeezing-out dynamics in free-standing smectic films

Energy Technology Data Exchange (ETDEWEB)

S̀liwa, Izabela, E-mail: izasliwa@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznaǹ (Poland); Vakulenko, A.A. [Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178 (Russian Federation); Zakharov, A.V., E-mail: alexandre.zakharov@yahoo.ca [Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178 (Russian Federation)

2016-05-06

Highlights: • We model the dynamics of layer transitions. • We model the thermally activated nucleation of a small hole. • We model the dynamics of squeezing-out one layer. - Abstract: We have carried out a theoretical study of the dynamics of the squeezing-out of one layer from the N-layer free-standing smectic film (FSSF) coupled with a meniscus, during the layer-thinning process. Squeezing-out is initiated by a thermally activated nucleation process in which a density fluctuation forms a small void in the center of the circular FSSF. The pressure gradient develops between the squeezed-out and nonsqueezed-out areas and is responsible for the driving out of one or several layer(s) from the N-layer smectic film. The dynamics of the boundary between these areas in the FSSF is studied by the use of the conservation laws for mass and linear momentum with accounting for the coupling between the meniscus and the smectic film. This coupling has a strong effect on the dynamics of the squeezing-out process and may significantly change the time which is needed to completely squeezed-out one or several layer(s) from the N-layer smectic film.

Estimating Carbon Dynamics in an Intact Lowland Mixed Dipterocarp Forest Using a Forest Carbon Model

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Jongyeol Lee

2017-04-01

Full Text Available Intact dipterocarp forests in Asia act as crucial carbon (C reservoirs, and it is therefore important to investigate the C dynamics in these forests. We estimated C dynamics, together with net ecosystem production (NEP, in an intact tropical dipterocarp forest of Brunei Darussalam. Fifty-four simulation units (plots; 20 m × 20 m were established and initial C stocks were determined via direct field measurement. The C dynamics were annually simulated with a regression model and the Forest Biomass and Dead organic matter Carbon (FBDC model. The initial C stock (Mg C·ha−1 of biomass, litter, dead wood and mineral soil were 213.1 ± 104.8, 2.0 ± 0.8, 31.3 ± 38.8, and 80.7 ± 15.5, respectively. Their annual changes (Mg C·ha−1·year−1 were 3.2 ± 1.1, 0.2 ± 0.2, −3.7 ± 6.1, and −0.3 ± 1.1, respectively. NEP was −0.6 ± 6.1 Mg C·ha−1·year−1, showing large heterogeneity among the plots. The initial C stocks of biomass and dead wood, biomass turnover rates and dead wood decay rates were elucidated as dominant factors determining NEP in a sensitivity analysis. Accordingly, investigation on those input data can constrain an uncertainty in determining NEP in the intact tropical forests.

Accumulation and connectivity of coarse woody debris in partial harvest and unmanaged relict forests.

Directory of Open Access Journals (Sweden)

Robert C Morrissey

Full Text Available When a tree dies, it continues to play an important ecological role within forests. Coarse woody debris (CWD, including standing deadwood (SDW and downed deadwood (DDW, is an important functional component of forest ecosystems, particularly for many dispersal-limited saproxylic taxa and for metapopulation dynamics across landscapes. Processes, such as natural disturbance or management, modify forest composition and structure, thereby influencing CWD abundance and distribution. Many studies have compared older forests to forests managed with even-aged silvicultural systems and observed a prolonged period of low CWD occurrence after harvesting. With fine-scale spatial data, our study compares the long-term impacts of light partial harvesting on the CWD structure of eastern deciduous hardwood forests. We mapped and inventoried DDW and SDW using variable radius plots based on a 10 m × 10 m grid throughout an unmanaged, structurally-complex relict forest and two nearby forests that were partially harvested over 46 years ago. The relict stand had significantly larger individual pieces and higher accumulations of DDW and SDW than both of the partially harvested stands. Connectivity of CWD was much higher in the relict stand, which had fewer, larger patches. Larger pieces and higher proportion of decay-resistant species (e.g. Quercus spp. in the relict forest resulted in slower decomposition, greater accumulation and increased connectivity of CWD. Partial harvests, such that occur with selection forestry, are generally considered less disruptive of ecosystem services, but this study highlights the long-term impacts of even light partial harvests on CWD stocks and distribution. When planning harvesting events, forest managers should also consider alternative methods to ensure the sustainability of deadwood resources and function.

Forest value and optimal rotations in continuous cover forestry

DEFF Research Database (Denmark)

Jacobsen, Jette Bredahl; Jensen, Frank; Thorsen, Bo Jellesmark

2018-01-01

The Faustmann forest rotation model is a celebrated contribution in economics. The model provides a forest value expression and allows a solution to the optimal rotation problem valid for perpetual rotations of even-aged forest stands. However, continuous forest cover forest management systems......, but rigorous mathematical model of the continuous cover forest, which strictly focuses on the area use dynamics that such an uneven-aged forest must have in equilibrium. This implies explicitly accounting for area reallocation and for weighting the productivity of each age class by the area occupied. We...... present results for unrestricted as well as area-restricted versions of the models. We find that land values are unambiguously higher in the continuous cover forest models compared with the even-aged models. Under area restrictions, the optimal rotation age in a continuous cover forest model...

Nutrient cycling in Huntington Forest and Turkey Lakes deciduous stands: Nitrogen and sulfur

Energy Technology Data Exchange (ETDEWEB)

Mitchell, M J [State Univ. of New York, Syracuse, NY (USA); Foster, N W; Morrison, I K [Forestry Canada, Sault Ste. Marie, ON (Canada); Shepard, J P [National Council of the Paper Industry for Air and Stream Improvement, Gainsville, FL (USA)

1992-01-01

A study was conducted to analyze two tolerant hardwood forests that are exhibiting different levels of nitrate and sulfate leaching. Fluxes of N and S at the two sites were compared, and the fluxes of nitrate and sulfate through the forest canopy, forest floor, and mineral soil were determined in order to ascertain whether differences in these fluxes could be explained using information on the N, S, and C biogeochemistry of each site. One site is in the Adirondack region, where the impacts of acidic deposition have been noted; the other site is in central Ontario, and has geological, pedological, and hydrological characteristics that make it potentially sensitive to acidic deposition. An increase in concentration of sulfate and nitrate was noted after passage through the canopy at both sites. The Ontario site showed much greater leaching of nitrate. At the Adirondack site only, there was a marked increase in sulfate flux when water leached from the forest floor through the soil. The mineral soil was the largest pool of N and S for both sites. The Ontario soil had a C/N ratio of 16:1, narrower than the 34:1 ratio of the soil at the other site. The former ratio should favor accumulation of ammonium and nitrate ions, and subsequent nitrate leaching. Laboratory measurements suggest that the forest floor at the Ontario site may have higher N mineralization rates. Fluxes of N and S within the vegetation were generally similar at both sites. The higher nitrate leaching at the Ontario site may be attributed mostly to stand maturity coupled with tree mortality, but the absence of slow decomposing beech leaf litter and lower C/N ratio in the soil may also be contributing factors. 50 refs., 3 figs., 6 tabs.

Drivers of forest cover dynamics in smallholder farming systems: the case of northwestern Vietnam.

Science.gov (United States)

Jadin, Isaline; Vanacker, Veerle; Hoang, Huong Thi Thu

2013-04-01

The national-scale forest recovery of Vietnam started in the early 1990s and is associated with a shift from net deforestation to net reforestation. Large disparities in forest cover dynamics are, however, observed at the local scale. This study aims to unravel the mechanisms driving forest cover change for a mountainous region located in northwest Vietnam. Statistical analyses were used to explore the association between forest cover change and household characteristics. In Sa Pa district, deforestation rates are decreasing, but forest degradation continues at similar rates. Deforestation is not necessarily associated with impoverished ethnic communities or high levels of subsistence farming, and the largest forest cover dynamics are found in villages with the best socio-economic conditions. Our empirical study does not provide strong evidence of a dominant role of agriculture in forest cover dynamics. It shows that empirical studies on local-scale forest dynamics remain important to unravel the complexity of human-environment interactions.

Assessing management effects on Oak forests in Austria

Science.gov (United States)

Gautam, Sishir; Pietsch, Stephan A.; Hasenauer, Hubert

2010-05-01

Historic land use as well as silvicultural management practices have changed the structures and species composition of central European forests. Such changes have effects on the growth of forests and contribute to global warming. As insufficient information on historic forest management is available it is hard to explain the effect of management on forests growth and its possible consequences to the environment. In this situation, the BIOME-BGC model, which integrates the main physical, biological and physiological processes based on current understanding of ecophysiology is an option for assessing the management effects through tracking the cycling of energy, water, carbon and nutrients within a given ecosystems. Such models are increasingly employed to simulate current and future forest dynamics. This study first compares observed standing tree volume, carbon and nitrogen content in soil in the high forests and coppice with standards stands of Oak forests in Austria. Biome BGC is then used to assess the effects of management on forest growth and to explain the differences with measured parameters. Close positive correlations and unbiased results and statistically insignificant differences between predicted and observed volumes indicates the application of the model as a diagnostic tool to assess management effects in oak forests. The observed data in 2006 and 2009 was further compared with the results of respective model runs. Further analysis on simulated data shows that thinning leads to an increase in growth efficiency (GE), nitrogen use efficiency (NUE) and water use efficiency (WUE), and to a decrease in the radiation use efficiency (RUE) in both forests. Among all studied growth parameters, only the difference in the NUE was statistically significant. This indicates that the difference in the yield of forests is mainly governed by the NUE difference in stands due to thinning. The coppice with standards system produces an equal amount of net primary

Red-cockaded woodpecker male/female foraging differences in young forest stands.

Energy Technology Data Exchange (ETDEWEB)

Franzreb, Kathleen, E.

2010-07-01

ABSTRACT The Red-cockaded Woodpecker (Picoides borealis) is an endangered species endemic to pine (Pinus spp.) forests of the southeastern United States. I examined Red-cockaded Woodpecker foraging behavior to learn if there were male/female differences at the Savannah River Site, South Carolina. The study was conducted in largely young forest stands (,50 years of age) in contrast to earlier foraging behavior studies that focused on more mature forest. The Redcockaded Woodpecker at the Savannah River site is intensively managed including monitoring, translocation, and installation of artificial cavity inserts for roosting and nesting. Over a 3-year period, 6,407 foraging observations covering seven woodpecker family groups were recorded during all seasons of the year and all times of day. The most striking differences occurred in foraging method (males usually scaled [45% of observations] and females mostly probed [47%]),substrate used (females had a stronger preference [93%] for the trunk than males [79%]), and foraging height from the ground (mean 6 SE foraging height was higher for males [11.1 6 0.5 m] than females [9.8 6 0.5 m]). Niche overlap between males and females was lowest for substrate (85.6%) and foraging height (87.8%), and highest for tree species (99.0%), tree condition (98.3%), and tree height (96.4%). Both males and females preferred to forage in older, large pine trees. The habitat available at the Savannah River Site was considerably younger than at most other locations, but the pattern of male/female habitat partitioning observed was similar to that documented elsewhere within the range attesting to the species’ ability to adjust behaviorally.

Modelling mixed forest growth : a review of models for forest management

NARCIS (Netherlands)

Porte, A.; Bartelink, H.H.

2002-01-01

Most forests today are multi-specific and heterogeneous forests (`mixed forests'). However, forest modelling has been focusing on mono-specific stands for a long time, only recently have models been developed for mixed forests. Previous reviews of mixed forest modelling were restricted to certain

Transpiration of montane Pinus sylvestris L. and Quercus pubescens Willd. forest stands measured with sap flow sensors in NE Spain

Directory of Open Access Journals (Sweden)

R. Poyatos

2005-01-01

Full Text Available Stand transpiration was measured during the 2003 and 2004 growing seasons using heat dissipation sap flow sensors in a Scots pine (Pinus sylvestris L. and a pubescent oak (Quercus pubescens Willd. forests located in a montane area of the Eastern Pyrenees (NE Spain. The first aim of the study was to assess the differences in quantitative estimates of transpiration (Ec and the response to evaporative demand of the two stands. Over the studied period of 2003, characterised by a severe drought episode during the summer, the oak stand (Ec was only 110 mm compared to the 239 mm transpired by the Scots pine stand, although the ratio of transpiration to reference evapotranspiration (Ec/ET0 in the oak stand compares well with the expected values predicted for low leaf area index (LAI oak forests in southern Europe. Scots pine showed a strong reduction in (Ec/ET0 as the drought developed, whereas pubescent oak was less affected by soil moisture deficits in the upper soil. As a second objective, and given the contrasting meteorological conditions between 2003 and 2004 summer periods, the interannual variability of transpiration was studied in the Scots pine plot. Rainfall during the summer months (June-September in 2003 was almost 40% less than in the same interval in 2004. Accordingly, transpiration was also reduced about 25% in 2003. Finally, Scots pine data from 2003 and 2004 was used to calibrate a simple transpiration model using ET0 and soil moisture deficit (SMD as input variables, and implicitly including stomatal responses to high vapour pressure deficits (Dd and soil water status.