WorldWideScience

Sample records for subpixel woody vegetation

  1. Patterns in woody vegetation structure across African savannas

    Science.gov (United States)

    Axelsson, Christoffer R.; Hanan, Niall P.

    2017-07-01

    Vegetation structure in water-limited systems is to a large degree controlled by ecohydrological processes, including mean annual precipitation (MAP) modulated by the characteristics of precipitation and geomorphology that collectively determine how rainfall is distributed vertically into soils or horizontally in the landscape. We anticipate that woody canopy cover, crown density, crown size, and the level of spatial aggregation among woody plants in the landscape will vary across environmental gradients. A high level of woody plant aggregation is most distinct in periodic vegetation patterns (PVPs), which emerge as a result of ecohydrological processes such as runoff generation and increased infiltration close to plants. Similar, albeit weaker, forces may influence the spatial distribution of woody plants elsewhere in savannas. Exploring these trends can extend our knowledge of how semi-arid vegetation structure is constrained by rainfall regime, soil type, topography, and disturbance processes such as fire. Using high-spatial-resolution imagery, a flexible classification framework, and a crown delineation method, we extracted woody vegetation properties from 876 sites spread over African savannas. At each site, we estimated woody cover, mean crown size, crown density, and the degree of aggregation among woody plants. This enabled us to elucidate the effects of rainfall regimes (MAP and seasonality), soil texture, slope, and fire frequency on woody vegetation properties. We found that previously documented increases in woody cover with rainfall is more consistently a result of increasing crown size than increasing density of woody plants. Along a gradient of mean annual precipitation from the driest (woody cover increased by 233, 73, and 491 % respectively. We also found a unimodal relationship between mean crown size and sand content suggesting that maximal savanna tree sizes do not occur in either coarse sands or heavy clays. When examining the occurrence of

  2. Patterns in woody vegetation structure across African savannas

    Directory of Open Access Journals (Sweden)

    C. R. Axelsson

    2017-07-01

    Full Text Available Vegetation structure in water-limited systems is to a large degree controlled by ecohydrological processes, including mean annual precipitation (MAP modulated by the characteristics of precipitation and geomorphology that collectively determine how rainfall is distributed vertically into soils or horizontally in the landscape. We anticipate that woody canopy cover, crown density, crown size, and the level of spatial aggregation among woody plants in the landscape will vary across environmental gradients. A high level of woody plant aggregation is most distinct in periodic vegetation patterns (PVPs, which emerge as a result of ecohydrological processes such as runoff generation and increased infiltration close to plants. Similar, albeit weaker, forces may influence the spatial distribution of woody plants elsewhere in savannas. Exploring these trends can extend our knowledge of how semi-arid vegetation structure is constrained by rainfall regime, soil type, topography, and disturbance processes such as fire. Using high-spatial-resolution imagery, a flexible classification framework, and a crown delineation method, we extracted woody vegetation properties from 876 sites spread over African savannas. At each site, we estimated woody cover, mean crown size, crown density, and the degree of aggregation among woody plants. This enabled us to elucidate the effects of rainfall regimes (MAP and seasonality, soil texture, slope, and fire frequency on woody vegetation properties. We found that previously documented increases in woody cover with rainfall is more consistently a result of increasing crown size than increasing density of woody plants. Along a gradient of mean annual precipitation from the driest (< 200 mm yr−1 to the wettest (1200–1400 mm yr−1 end, mean estimates of crown size, crown density, and woody cover increased by 233, 73, and 491 % respectively. We also found a unimodal relationship between mean crown size and sand

  3. Biomass increases go under cover: woody vegetation dynamics in South African rangelands

    CSIR Research Space (South Africa)

    Mograbi, PJ

    2015-05-01

    Full Text Available Woody biomass dynamics are an expression of ecosystem function, yet biomass estimates do not provide information on the spatial distribution of woody vegetation within the vertical vegetation subcanopy. We demonstrate the ability of airborne light...

  4. Diversity and structure of woody vegetation across areas with ...

    African Journals Online (AJOL)

    Here we investigate the differences and/or similarities of woody vegetation diversity and structure across areas with different edaphic factors (i.e. soil group) in Gonarezhou National Park, Zimbabwe. We stratified our study area into two strata based on soil group, namely siallitic soil in northern Gonarezhou and regosol soil ...

  5. State and trends of woody vegetation cover inthe cotton based ...

    African Journals Online (AJOL)

    This study was carried out in Bala, a village located in the cotton-based farming system zone of Western Burkina Faso. The objective was to assess the effect of increased cotton cultivation on the spatial dynamics and structural characteristics of the woody vegetation. Using aerial photos, an analysis of the land use for the ...

  6. dryland woody vegetation along an altitudinal gradient

    African Journals Online (AJOL)

    communities under high grazing pressure and other disturbance are poor in species richness. Most of the vegetation was observed highly disturbed except along inaccessible steep slopes, and in few protected and privately owned areas indicating some implications of conservation and management. The vegetation was ...

  7. Application of Bridge Pier Scour Equations for Large Woody Vegetation

    Science.gov (United States)

    2016-07-01

    around trees Sheppard-Melville method Woody vegetation Bridges-Foundations & piers Scour (Hydraulic engineering ) Roots (Botany) Trees Levees Embankments Numerical analysis ...Development Center (ERDC) solves the nation’s toughest engineering and environmental challenges. ERDC develops innovative solutions in civil and...to develop prediction methods for scour associated with fallen trees. ERDC TR-16-10 4 The U.S. Army Corps of Engineers (USACE) guidance for

  8. Effect of controlling herbaceous and woody competing vegetation on wood quality of planted loblolly pine

    Science.gov (United States)

    Alexander Clark; Richard F. Daniels; James H. Miller

    2006-01-01

    Southern pine plantations are increasingly established using herbicides to control herbaceous and/or woody competing vegetation to enhance growth, but little is known about the effect on wood quality. A study was established at 13 southern locations in 1984 to examine the effects of complete control of woody, herbaceous, and woody plus herbaceous competition for the...

  9. Variation in woody vegetation structure and composition in a semi-arid savanna of southern Zimbabwe

    NARCIS (Netherlands)

    Zisadza-Gandiwa, P.; Mango, N.; Gandiwa, E.; Goza, D.; Parakasingwa, C.; Chinoitezvi, E.; Shimbani, J.; Muvengwi, J.

    2013-01-01

    The objectives of this study were: i) to establish the status of woody vegetation structure and composition, and ii) to determine the main factors influencing woody vegetation structure and composition across Gonarezhou National Park, Zimbabwe. We divided the park into three large strata based on

  10. Effect of patches of woody vegetation on the role of fire in tropical grasslands and savannas

    NARCIS (Netherlands)

    Langevelde, van F.; Groot, de C.; Groen, T.A.; Heitkonig, I.M.A.; Gaigher, I.

    2014-01-01

    In tropical grasslands and savannas, fire is used to reduce woody vegetation expansion. Woody vegetation in these biomes is often patchily distributed, and micro-climatic conditions can largely vary locally with unknown consequences for fire effects. We hypothesized that (1) fire has higher

  11. Structure and composition of woody vegetation in two important bird areas in southern Zimbabwe

    NARCIS (Netherlands)

    Gandiwa, P.; Chinoitezvi, E.; Gandiwa, E.

    2013-01-01

    This study assessed the status of woody vegetation structure and composition in two Important Bird Areas (IBA) i.e. Manjinji Pan and Save-Runde Junction located in southeastern Zimbabwe. The objectives of this study were to: (i) determine the woody vegetation structure and composition of the study

  12. Spatial vegetation patterns and neighborhood competition among woody plants in an East African savanna.

    Science.gov (United States)

    Dohn, Justin; Augustine, David J; Hanan, Niall P; Ratnam, Jayashree; Sankaran, Mahesh

    2017-02-01

    The majority of research on savanna vegetation dynamics has focused on the coexistence of woody and herbaceous vegetation. Interactions among woody plants in savannas are relatively poorly understood. We present data from a 10-yr longitudinal study of spatially explicit growth patterns of woody vegetation in an East African savanna following exclusion of large herbivores and in the absence of fire. We examined plant spatial patterns and quantified the degree of competition among woody individuals. Woody plants in this semiarid savanna exhibit strongly clumped spatial distributions at scales of 1-5 m. However, analysis of woody plant growth rates relative to their conspecific and heterospecific neighbors revealed evidence for strong competitive interactions at neighborhood scales of up to 5 m for most woody plant species. Thus, woody plants were aggregated in clumps despite significantly decreased growth rates in close proximity to neighbors, indicating that the spatial distribution of woody plants in this region depends on dispersal and establishment processes rather than on competitive, density-dependent mortality. However, our documentation of suppressive effects of woody plants on neighbors also suggests a potentially important role for tree-tree competition in controlling vegetation structure and indicates that the balanced-competition hypothesis may contribute to well-known patterns in maximum tree cover across rainfall gradients in Africa. © 2016 by the Ecological Society of America.

  13. Decline of woody vegetation in a saline landscape in the Groundnut Basin, Senegal

    DEFF Research Database (Denmark)

    Sambou, Antoine; Theilade, Ida; Fensholt, Rasmus

    2016-01-01

    perceived a general decline of woody plants from 1993 to 2013. Among 60 species mentioned by local people, 90 % were declining and 10 % increasing. Together the three methods documented a decrease in density and diversity of the woody vegetation, mainly influenced by salinity and land use. The large numbers...... cover, herbaceous cover and tans (highly saline areas with sparse vegetation). Although the trend was the same, the three villages had different vegetation histories. A survey of the woody vegetation showed that shrubs and young trees were dominating with relatively few large trees. Local people...

  14. Effect of a single fire on woody vegetation in Catchment IX ...

    African Journals Online (AJOL)

    Fire is a key driver in shaping and maintaining grasslands. Long-term exclusion of fire in moist grasslands has been attempted at Catchment IX (CIX) at Cathedral Peak since 1952. Vegetation was surveyed in 1952, 1973, 1986 and 2009. Woody colonisation into grasslands was the most noted change over time. The woody ...

  15. NACP Woody Vegetation Characteristics of 1,039 Sites across the North Slope, Alaska

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides the results of (1) field measurements of woody vegetation (shrubs) at 26 diverse sites across the North Slope of Alaska during 2010 and 2011,...

  16. Mapping gains and losses in woody vegetation across global tropical drylands

    DEFF Research Database (Denmark)

    Tian, Feng; Brandt, Martin Stefan; Liu, Yi Y

    2017-01-01

    , the actual changes in the woody vegetation are always hidden by interannual fluctuations of the leaf density, because the most widely used remote sensing data are primarily related to the photosynthetically active vegetation components. Here, we quantify the temporal trends of the nonphotosynthetic woody......Woody vegetation in global tropical drylands is of significant importance for both the interannual variability of the carbon cycle and local livelihoods. Satellite observations over the past decades provide a unique way to assess the vegetation long-term dynamics across biomes worldwide. Yet...... components (i.e., stems and branches) in global tropical drylands during 2000-2012 using the vegetation optical depth (VOD), retrieved from passive microwave observations. This is achieved by a novel method focusing on the dry season period to minimize the influence of herbaceous vegetation and using...

  17. Savanna woody vegetation classification – now in 3-D

    CSIR Research Space (South Africa)

    Fisher, JT

    2013-05-01

    Full Text Available The co-existence of woody plants and grasses characterize savannas, with the horizontal and vertical spatial arrangement of trees creating a heterogeneous biotic environment. To understand the influence of biogeophysical drivers on the spatial...

  18. SAFARI 2000 Woody Vegetation Characteristics of Kalahari and Skukuza Sites

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set contains species composition, basal area, height, and crown cover of all woody plants at six sites along the Kalahari Transect visited in...

  19. SAFARI 2000 Woody Vegetation Characteristics of Kalahari and Skukuza Sites

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains species composition, basal area, height, and crown cover of all woody plants at six sites along the Kalahari Transect visited in...

  20. Understory vegetation, resource availability, and litterfall responses to pine thinning and woody vegetation control in longleaf pine plantations

    Science.gov (United States)

    Timothy B. Harrington; M. Boyd. Edwards

    1999-01-01

    In six 8- to 11-year-old plantations of longleaf pine (Pinus palustris Mill.) near Aiken, S.C., responses of understory vegetation, light, and soil water availability and litterfall were studied in relation to pine thinning (May 1994), herbicidal treatment of nonpine woody vegetation (1995-1996), or the combined treatments (treatment responses...

  1. Savannah fractional woody vegetation cover mapping with optical and radar data and machine learning

    Science.gov (United States)

    Symeonakis, Elias; Marqués-Mateu, Ángel; Petroulaki, Kyriaki; Higginbottom, Thomas

    2017-04-01

    The fraction of woody vegetation plays an important role in natural and anthropogenic processes of savannah ecosystems. We investigate the optimal combination of Landsat optical and thermal bands as well as ALOS PALSAR L-band radar data from both wet and dry seasons for the mapping of fractional woody vegetation cover in southern African savannah environments. We employ colour aerial photography for sampling and validation and a random forest classification approach to map the fraction of woody cover in the Northwest Province of South Africa. Our results from random forests classifications show that the most accurate estimates are produced from the model that incorporates all parameters: Landsat optical and thermal bands and vegetation indices for the dry and wet seasons, and HH and HV polarised ALOS PALSAR L-band data. However, the combination of the six Landsat bands from either the wet or the dry season with either the HH or the HV PALSAR band, appears to be sufficient for achieving fractional woody cover balanced accuracies of >85%. Dry season optical bands alone are able to map fractional woody cover with more than 80% balanced accuracy. Our findings can provide much needed assistance to woody vegetation monitoring efforts in southern African savannahs where its expansion over the last decades is partly attributed to bush encroachment and land degradation brought about by recent climatic changes and/or land mismanagement.

  2. The flora of woody plants and vegetation on the Horn of Africa

    DEFF Research Database (Denmark)

    Friis, Ib

    2017-01-01

    There are about one thousand species of woody plants that occur naturally on the Horn of Africa, including trees and large shrubs, and they have many functions in the highly varied ecosystem on the Horn, including soil conservation and the prevention of flooding during tropical rainstorms...... on the Horn since 1970, aims at describing and mapping the woody plants, the vegetation types they form, and the ways in which the local population interacts with them. The nearer aims are to produce manuals and scientific publications on the flora, including an improved map of the vegetation. Due to long....... For historical reasons, the woody flora and the vegetation types they form have been less studied than in most other parts of Africa, and new species of even rather large shrubs or trees are still discovered, named and described. This project, which is part of an involvement with the flora and vegetation...

  3. LANDSAT-BASED WOODY VEGETATION COVER MONITORING IN SOUTHERN AFRICAN SAVANNAHS

    Directory of Open Access Journals (Sweden)

    E. Symeonakis

    2016-06-01

    Full Text Available Mapping woody cover over large areas can only be effectively achieved using remote sensing data and techniques. The longest continuously operating Earth-observation program, the Landsat series, is now freely-available as an atmospherically corrected, cloud masked surface reflectance product. The availability and length of the Landsat archive is thus an unparalleled Earth-observation resource, particularly for long-term change detection and monitoring. Here, we map and monitor woody vegetation cover in the Northwest Province of South Africa, an area of more than 100,000 km2 covered by 11 Landsat scenes. We employ a multi-temporal approach with dry-season data from 7 epochs between 1990 to 2015. We use 0.5 m-pixel colour aerial photography to collect > 15,000 point samples for training and validating Random Forest classifications of (i woody vegetation cover, (ii other vegetation types (including grasses and agricultural land, and (iii non-vegetated areas (i.e. urban areas and bare land. Overall accuracies for all years are around 80 % and overall kappa between 0.45 and 0.66. Woody vegetation covers a quarter of the Province and is the most accurately mapped class (balanced accuracies between 0.74-0.84 for the 7 epochs. There is a steady increase in woody vegetation cover over the 25-year-long period of study in the expense of the other vegetation types. We identify potential woody vegetation encroachment 'hot-spots' where mitigation measures might be required and thus provide a management tool for the prioritisation of such measures in degraded and food-insecure areas.

  4. Landsat-Based Woody Vegetation Cover Monitoring in Southern African Savannahs

    Science.gov (United States)

    Symeonakis, E.; Petroulaki, K.; Higginbottom, T.

    2016-06-01

    Mapping woody cover over large areas can only be effectively achieved using remote sensing data and techniques. The longest continuously operating Earth-observation program, the Landsat series, is now freely-available as an atmospherically corrected, cloud masked surface reflectance product. The availability and length of the Landsat archive is thus an unparalleled Earth-observation resource, particularly for long-term change detection and monitoring. Here, we map and monitor woody vegetation cover in the Northwest Province of South Africa, an area of more than 100,000 km2 covered by 11 Landsat scenes. We employ a multi-temporal approach with dry-season data from 7 epochs between 1990 to 2015. We use 0.5 m-pixel colour aerial photography to collect > 15,000 point samples for training and validating Random Forest classifications of (i) woody vegetation cover, (ii) other vegetation types (including grasses and agricultural land), and (iii) non-vegetated areas (i.e. urban areas and bare land). Overall accuracies for all years are around 80 % and overall kappa between 0.45 and 0.66. Woody vegetation covers a quarter of the Province and is the most accurately mapped class (balanced accuracies between 0.74-0.84 for the 7 epochs). There is a steady increase in woody vegetation cover over the 25-year-long period of study in the expense of the other vegetation types. We identify potential woody vegetation encroachment 'hot-spots' where mitigation measures might be required and thus provide a management tool for the prioritisation of such measures in degraded and food-insecure areas.

  5. Transition of a Sambucus nigra L. dominated woody vegetation into grassland by a self regulating multi-species herbivore assemblage

    NARCIS (Netherlands)

    Cornelissen, P.; Gresnigt, M.C.; Vermeulen, R.A.; Bokdam, J.; Smit, R.

    2014-01-01

    We describe and analyse how large herbivores strongly diminished a woody vegetation, dominated by the unpalatable shrub Sambucus nigra L. and changed it into grassland. Density of woody species and cover of vegetation were measured in 1996, 2002 and 2012 in the grazed Oostvaardersplassen. In 2002

  6. Human-modified landscapes: patterns of fine-scale woody vegetation structure in communal savannah rangelands

    CSIR Research Space (South Africa)

    Fisher, T

    2011-11-01

    Full Text Available precipitation at one site, and human population density and intensity of use at the other four sites. Size class distributions of woody vegetation revealed human disturbance gradients around settlements. Intensity of use affected the amplitude, not the shape...

  7. Seasonal Biennial Burning and Woody Plant Control Influence Native Vegetation in Loblolly Pine Stands

    Science.gov (United States)

    James D. Haywood; Alton Martin; Henry A. Pearson; Harold E. Grelen

    1998-01-01

    This paper documents the results of a study to determine the effects of selectedvegetation-management treatments in loblolly pine. Vegetation in precommercially thinned, 6-year-old stands was subjected to five biennial growing season burns in either early March, May, or July coupled with hand felling of residual woody stems. Using a randomized complete block design, we...

  8. Evaluation of potential of woody species vegetation components in objects of landscape architecture

    Directory of Open Access Journals (Sweden)

    Miloš Pejchal

    2012-01-01

    Full Text Available Potential of woody species vegetation components is defined as the total ability of existing woody species vegetation components (hereinafter referred to as WSVC of a particular object (or its parts to ensure the composition stability. The main criteria for evaluation of this potential at all levels are: (a current (relevant characteristics of WSVC; (b expected development of ability of WSVC to preserve, renew and develop its desirable characteristics; (c expected length of biologically conditioned existence of WSVC (in an acceptable condition; and (d expected length of desirable existence of WSVC.Evaluation is based on mutual confrontation and interpretation of especially these woody species characteristics: taxon, age or development stage and landscaping value. These characteristics are surveyed during the evaluation of woody species as standard in the Czech Republic, or at least at a fairly regular basis. It proceeds from the lowest level (individual to the highest level (the whole object. Especially in case of larger objects and their parts is used as a basis the spatial distribution of the aforementioned characteristics in the evaluated unit (terrain layout as well as statistical evaluation of these characteristics.The focuses of this paper are methodological issues of determining and expressing the potential of woody species components.

  9. Modeling woody vegetation resources using Landsat TM imagery in ...

    African Journals Online (AJOL)

    ... remote sensing were compared with volume estimates obtained by field inventories. All fell within 95 % confidence limits of the field estimates. The results suggest that Landsat TM imagery is suitable for estimating tree cover, volumes and biomass on a regional scale for dry semideciduous Kalahari woodland vegetation.

  10. Woody vegetation status on different altitudinal gradients of an ...

    African Journals Online (AJOL)

    Altitude plays key roles in determining plant distribution and biodiversity patterns. The importance of vegetation should not be undermined because it is one of the primary factors that determine the eligibility of ecotourism sites. This study was undertaken at Arinta Waterfall, Ekiti State, Nigeria with an aim to determine the ...

  11. Eleventh-year response of loblolly pine and competing vegetation to woody and herbaceous plant control on a Georgia flatwoods site

    Science.gov (United States)

    Bruce R. Zutter; James H. Miller

    1998-01-01

    Through 11 growing seasons, growth of loblolly pine (Pinus taeda L.) increased after control of herbaceous, woody, or both herbaceous and woody vegetation (total control) for the first 3 years after planting on a bedded site in the Georgia coastal flatwoods. Gains in stand volume index from controlling either herbaceous or woody vegetation alone were approximately two-...

  12. Spatial-structural analysis of leafless woody riparian vegetation for hydraulic considerations

    Science.gov (United States)

    Weissteiner, Clemens; Jalonen, Johanna; Järvelä, Juha; Rauch, Hans Peter

    2013-04-01

    Woody riparian vegetation is a vital element of riverine environments. On one hand woody riparian vegetation has to be taken into account from a civil engineering point of view due to boundary shear stress and vegetation drag. On the other hand it has to be considered from a river ecological point of view due to shadowing effects and as a source of organic material for aquatic habitats. In hydrodynamic and hydro-ecological studies the effects of woody riparian vegetation on flow patterns are usually investigated on a very detailed level. On the contrary vegetation elements and their spatial patterns are generally analysed and discussed on the basis of an integral approach measuring for example basal diameters, heights and projected plant areas. For a better understanding of the influence of woody riparian vegetation on turbulent flow and on river ecology, it is essential to record and analyse plant data sets on the same level of quality as for hydrodynamic or hydro-ecologic purposes. As a result of the same scale of the analysis it is possible to incorporate riparian vegetation as a sub-model in the hydraulic analysis. For plant structural components, such as branches on different topological levels it is crucial to record plant geometrical parameters describing the habitus of the plant on branch level. An exact 3D geometrical model of real plants allows for an extraction of various spatial-structural plant parameters. In addition, allometric relationships help to summarize and describe plant traits of riparian vegetation. This paper focuses on the spatial-structural composition of leafless riparia woddy vegetation. Structural and spatial analyses determine detailed geometric properties of the structural components of the plants. Geometrical and topological parameters were recorded with an electro-magnetic scanning device. In total, 23 plants (willows, alders and birches) were analysed in the study. Data were recorded on branch level, which allowed for the

  13. Biomass Increases Go under Cover: Woody Vegetation Dynamics in South African Rangelands.

    Science.gov (United States)

    Mograbi, Penelope J; Erasmus, Barend F N; Witkowski, E T F; Asner, Gregory P; Wessels, Konrad J; Mathieu, Renaud; Knapp, David E; Martin, Roberta E; Main, Russell

    2015-01-01

    Woody biomass dynamics are an expression of ecosystem function, yet biomass estimates do not provide information on the spatial distribution of woody vegetation within the vertical vegetation subcanopy. We demonstrate the ability of airborne light detection and ranging (LiDAR) to measure aboveground biomass and subcanopy structure, as an explanatory tool to unravel vegetation dynamics in structurally heterogeneous landscapes. We sampled three communal rangelands in Bushbuckridge, South Africa, utilised by rural communities for fuelwood harvesting. Woody biomass estimates ranged between 9 Mg ha(-1) on gabbro geology sites to 27 Mg ha(-1) on granitic geology sites. Despite predictions of woodland depletion due to unsustainable fuelwood extraction in previous studies, biomass in all the communal rangelands increased between 2008 and 2012. Annual biomass productivity estimates (10-14% p.a.) were higher than previous estimates of 4% and likely a significant contributor to the previous underestimations of modelled biomass supply. We show that biomass increases are attributable to growth of vegetation wood extraction rangeland, 79% of the changes in the vertical vegetation subcanopy are gains in the 1-3 m height class. The higher the wood extraction pressure on the rangelands, the greater the biomass increases in the low height classes within the subcanopy, likely a strong resprouting response to intensive harvesting. Yet, fuelwood shortages are still occurring, as evidenced by the losses in the tall tree height class in the high extraction rangeland. Loss of large trees and gain in subcanopy shrubs could result in a structurally simple landscape with reduced functional capacity. This research demonstrates that intensive harvesting can, paradoxically, increase biomass and this has implications for the sustainability of ecosystem service provision. The structural implications of biomass increases in communal rangelands could be misinterpreted as woodland recovery in the

  14. Biomass Increases Go under Cover: Woody Vegetation Dynamics in South African Rangelands.

    Directory of Open Access Journals (Sweden)

    Penelope J Mograbi

    Full Text Available Woody biomass dynamics are an expression of ecosystem function, yet biomass estimates do not provide information on the spatial distribution of woody vegetation within the vertical vegetation subcanopy. We demonstrate the ability of airborne light detection and ranging (LiDAR to measure aboveground biomass and subcanopy structure, as an explanatory tool to unravel vegetation dynamics in structurally heterogeneous landscapes. We sampled three communal rangelands in Bushbuckridge, South Africa, utilised by rural communities for fuelwood harvesting. Woody biomass estimates ranged between 9 Mg ha(-1 on gabbro geology sites to 27 Mg ha(-1 on granitic geology sites. Despite predictions of woodland depletion due to unsustainable fuelwood extraction in previous studies, biomass in all the communal rangelands increased between 2008 and 2012. Annual biomass productivity estimates (10-14% p.a. were higher than previous estimates of 4% and likely a significant contributor to the previous underestimations of modelled biomass supply. We show that biomass increases are attributable to growth of vegetation <5 m in height, and that, in the high wood extraction rangeland, 79% of the changes in the vertical vegetation subcanopy are gains in the 1-3 m height class. The higher the wood extraction pressure on the rangelands, the greater the biomass increases in the low height classes within the subcanopy, likely a strong resprouting response to intensive harvesting. Yet, fuelwood shortages are still occurring, as evidenced by the losses in the tall tree height class in the high extraction rangeland. Loss of large trees and gain in subcanopy shrubs could result in a structurally simple landscape with reduced functional capacity. This research demonstrates that intensive harvesting can, paradoxically, increase biomass and this has implications for the sustainability of ecosystem service provision. The structural implications of biomass increases in communal rangelands

  15. Biomass Increases Go under Cover: Woody Vegetation Dynamics in South African Rangelands

    Science.gov (United States)

    Mograbi, Penelope J.; Knapp, David E.; Martin, Roberta E.; Main, Russell

    2015-01-01

    Woody biomass dynamics are an expression of ecosystem function, yet biomass estimates do not provide information on the spatial distribution of woody vegetation within the vertical vegetation subcanopy. We demonstrate the ability of airborne light detection and ranging (LiDAR) to measure aboveground biomass and subcanopy structure, as an explanatory tool to unravel vegetation dynamics in structurally heterogeneous landscapes. We sampled three communal rangelands in Bushbuckridge, South Africa, utilised by rural communities for fuelwood harvesting. Woody biomass estimates ranged between 9 Mg ha-1 on gabbro geology sites to 27 Mg ha-1 on granitic geology sites. Despite predictions of woodland depletion due to unsustainable fuelwood extraction in previous studies, biomass in all the communal rangelands increased between 2008 and 2012. Annual biomass productivity estimates (10–14% p.a.) were higher than previous estimates of 4% and likely a significant contributor to the previous underestimations of modelled biomass supply. We show that biomass increases are attributable to growth of vegetation biomass increases in the low height classes within the subcanopy, likely a strong resprouting response to intensive harvesting. Yet, fuelwood shortages are still occurring, as evidenced by the losses in the tall tree height class in the high extraction rangeland. Loss of large trees and gain in subcanopy shrubs could result in a structurally simple landscape with reduced functional capacity. This research demonstrates that intensive harvesting can, paradoxically, increase biomass and this has implications for the sustainability of ecosystem service provision. The structural implications of biomass increases in communal rangelands could be misinterpreted as woodland recovery in the absence of three-dimensional, subcanopy information. PMID:25969985

  16. Species composition and diversity of non-forest woody vegetation along roads in the agricultural landscape

    Directory of Open Access Journals (Sweden)

    Tóth Attila

    2016-03-01

    Full Text Available Non-forest woody vegetation represents an important component of green infrastructure in the agricultural landscape, where natural and semi-natural forest cover has only a low land use proportion. This paper focuses on linear woody vegetation structures along roads in the agricultural landscape and analyses them in three study areas in the Nitra Region, Slovakia. We evaluate species composition and diversity, species occurrence frequency or spatial distribution, their structure according to relatively achievable age and origin. For the evaluation of occurrence frequency, a Frequency Factor was proposed and applied. This factor allows a better comparison of different study areas and results in more representative findings. The study areas were divided into sectors based on visual landscape features, which are easily identifiable in the field, such as intersections and curves in roads, and intersections of roads with other features, such as cadastral or land boundaries, watercourses, etc. Based on the species abundance, woody plants present within the sectors were categorised into 1 predominant, 2 complementary and 3 mixed-in species; and with regard to their origin into 1 autochthonous and 2 allochthonous. Further, trees were categorised into 1 long-lived, 2 medium-lived and 3 short-lived tree species. The main finding is that among trees, mainly allochthonous species dominated. Robinia pseudoacacia L. was the predominant tree species in all three study areas. It was up to 4 times more frequent than other predominant tree species. Introduced tree species prevailed also among complementary and mixed-in species. Among shrubs, mainly native species dominated, while non-native species had a significantly lower proportion and spatial distribution. Based on these findings, several measures have been proposed to improve the overall ecological stability, the proportion and spatial distribution of native woody plant species. The recommendations and

  17. Classification and mapping of the woody vegetation of Gonarezhou National Park, Zimbabwe

    Directory of Open Access Journals (Sweden)

    Francesco Martini

    2016-03-01

    Full Text Available Within the framework of the Great Limpopo Transfrontier Conservation Area (GLTFCA, the purpose of this study was to produce a classification of the woody vegetation of the Gonarezhou National Park, Zimbabwe, and a map of its potential distribution. Cover-abundance data of woody species were collected in 330 georeferenced relevés across the Park. These data were used to produce two matrices: the first one using the cover-abundance values as collected in five height layers and the second one based on merging the layers into a single cover value for each species. Automatic classifications were produced for both matrices to determine the optimal number of vegetation types. The two classification approaches both produced 14 types belonging to three macro-groups: mopane, miombo and alluvial woodlands. The results of the two classifications were compared looking at the constant, dominant and diagnostic species of each type. The classification based on separate layers was considered more effective and retained. A high-resolution map of the potential distribution of vegetation types for the whole study area was produced using Random Forest. In the model, the relationship between bioclimatic and topographic variables, known to be correlated to vegetation types, and the classified relevés was used. Identified vegetation types were compared with those of other national parks within the GLTFCA, and an evaluation of the main threats and pressures was conducted.Conservation implications: Vegetation classification and mapping are useful tools for multiple purposes including: surveying and monitoring plant and animal populations, communities and their habitats, and development of management and conservation strategies. Filling the knowledge gap for the Gonarezhou National Park provides a basis for standardised and homogeneous vegetation classification and mapping for the entire Great Limpopo Transfrontier Conservation Area.

  18. Effects of rainfall intensity and intermittency on woody vegetation cover and deep soil moisture in dryland ecosystems

    Science.gov (United States)

    Zhang, Ding-Hai; Li, Xin-Rong; Zhang, Feng; Zhang, Zhi-Shan; Chen, Yong-Le

    2016-12-01

    Identifying the relationship between the stochastic daily rainfall regime and the dynamics of plants and soil moisture is fundamental for the sustainable management of dryland ecosystems in a context of global climate change. An eco-hydrological model that couples the dynamics of woody vegetation cover and deep soil moisture (typically with a depth interval of 30-150 cm) was used to investigate the effect of stochastic intensity and the intermittency of precipitation on soil moisture in this deep interval, which affects woody vegetation cover. Our results suggest that the precipitation intensity and intermittency play an important role in the dynamics of wood vegetation cover and deep soil moisture. In arid and semiarid regions, as the annual precipitation increased, the rate of woody vegetation cover increased as a power-law function, and the deep soil moisture increased exponentially. For a given annual rainfall, there were positive correlations between the rainfall intensity (or rainfall intermittency) and both the woody vegetation cover and deep soil moisture. The positive correlations between wood vegetation cover and both rainfall intensity and intermittency may decrease with increases in the precipitation intensity or precipitation intermittency. The positive correlations between deep soil moisture and both rainfall intensity and rainfall intermittency increase as the precipitation intensity or precipitation intermittency increases. Moreover, these positive correlations may increase with increases in the mean annual rainfall. Our results emphasize the importance of daily precipitation variations in controlling the responses of woody vegetation cover and deep soil moisture to climate variations in arid and semiarid regions. Our model can aid the understanding of rainfall processes and indicates that increases in rainfall intensity or rainfall intermittency may lead to an increase in woody vegetation cover and deep soil moisture given an invariable annual

  19. Human population growth offsets climate-driven increase in woody vegetation in sub-Saharan Africa

    DEFF Research Database (Denmark)

    Brandt, Martin Stefan; Rasmussen, Kjeld; Peñuelas, Josep

    2017-01-01

    The rapidly growing human population in sub-Saharan Africa generates increasing demand for agricultural land and forest products, which presumably leads to deforestation. Conversely, a greening of African drylands has been reported, but this has been difficult to associate with changes in woody...... cover were associated with high population growth. The spatially distinct pattern of these opposing trends reflects, first, the natural response of vegetation to precipitation and atmospheric CO2, and second, deforestation in humid areas, minor in size but important for ecosystem services...

  20. Environmental Impacts and Costs of Hydrotreated Vegetable Oils, Transesterified Lipids and Woody BTL—A Review

    Directory of Open Access Journals (Sweden)

    Andreas Brekke

    2011-05-01

    Full Text Available This article reviews and compares assessments of three biodiesel fuels: (1 transesterified lipids, (2 hydrotreated vegetable oils (HVO, and (3 woody biomass-to-liquid (BTL Fischer-Tropsch diesel and selected feedstock options. The article attempts to rank the environmental performance and costs of fuel and feedstock combinations. Due to inter-study differences in goal and study assumptions, the ranking was mostly qualitative and intra-study results are emphasized. Results indicate that HVO made from wastes or by-products such as tall oil, tallow or used cooking oil outperform transesterified lipids and BTL from woody material, both with respect to environmental life cycle impacts and costs. These feedstock options are, however, of limited availability, and to produce larger volumes of biofuels other raw materials must also be used. BTL from woody biomass seems promising with good environmental performance and the ability not to compete with food production. Production of biofuels from agricultural feedstock sources requires much energy and leads to considerable emissions due to agrochemical inputs. Thus, such biodiesel fuels are ranked lowest in this comparison. Production of feedstock is the most important life cycle stage. Avoiding detrimental land use changes and maintaining good agricultural or forestry management practices are the main challenges to ensure that biofuels can be a sustainable option for the future transport sector.

  1. Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds.

    Directory of Open Access Journals (Sweden)

    Nicholas R Vaughn

    Full Text Available Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50-450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques.

  2. Multiple Scales of Control on the Structure and Spatial Distribution of Woody Vegetation in African Savanna Watersheds.

    Science.gov (United States)

    Vaughn, Nicholas R; Asner, Gregory P; Smit, Izak P J; Riddel, Edward S

    2015-01-01

    Factors controlling savanna woody vegetation structure vary at multiple spatial and temporal scales, and as a consequence, unraveling their combined effects has proven to be a classic challenge in savanna ecology. We used airborne LiDAR (light detection and ranging) to map three-dimensional woody vegetation structure throughout four savanna watersheds, each contrasting in geologic substrate and climate, in Kruger National Park, South Africa. By comparison of the four watersheds, we found that geologic substrate had a stronger effect than climate in determining watershed-scale differences in vegetation structural properties, including cover, height and crown density. Generalized Linear Models were used to assess the spatial distribution of woody vegetation structural properties, including cover, height and crown density, in relation to mapped hydrologic, topographic and fire history traits. For each substrate and climate combination, models incorporating topography, hydrology and fire history explained up to 30% of the remaining variation in woody canopy structure, but inclusion of a spatial autocovariate term further improved model performance. Both crown density and the cover of shorter woody canopies were determined more by unknown factors likely to be changing on smaller spatial scales, such as soil texture, herbivore abundance or fire behavior, than by our mapped regional-scale changes in topography and hydrology. We also detected patterns in spatial covariance at distances up to 50-450 m, depending on watershed and structural metric. Our results suggest that large-scale environmental factors play a smaller role than is often attributed to them in determining woody vegetation structure in southern African savannas. This highlights the need for more spatially-explicit, wide-area analyses using high resolution remote sensing techniques.

  3. WILDFIRE INDUCED DEGRADATION OF WOODY VEGETATION IN DRY ZONE OF KAZAKHSTAN

    Directory of Open Access Journals (Sweden)

    A. Terekhov

    2012-08-01

    Full Text Available Small bushy tree species dominate the semi-arid areas of Kazakhstan. In the course of their life cycle, they form a layer of litter that is resistant to wind transport. This small shrub species with its own litter play a significant role in the spectral characteristics of the Earth surface. Changes in the density of shrub canopy forms or replacing them with herbaceous species is accompanied by significant changes in the spectral characteristics in the visible and near infrared spectral bands in the autumn. These changes can be recorded from satellite data. LANDSAT-TM images during 1985–2007 years and MODIS data (USGS: MOD09Q1, 2000–2010 used to diagnose changes in relation between woody\\herbaceous vegetation species in the dry zone of Kazakhstan. It was found that over the past 10 years, spreading small shrub forms of semi-arid vegetation significantly decreased. There is a persistent expansion of herbal forms, leading to the semi-steppe formation areas. The mechanism of repression of wood forms constructed through the accumulation of dry plant mass during wet years, with its subsequent burnout during wildfires. In the case of a strong fire, a complete destruction of species is observed. The restoration of small shrub cover demands more than 20 years. Comparative analysis of LANDSAT-TM images showed a 10 times increasing of the fire scar areas in the test area in the central part of Kazakhstan between 1985 and 2007. According MOD09Q1 was conducted mapping small shrub forms of degradation in Kazakhstan. Reducing the area occupied by woody vegetation, semi-desert was about 30 million hectares or over 30% of their total range in Kazakhstan.

  4. Effects of woody vegetation on overbank sand transport during a large flood, Rio Puerco, New Mexico

    Science.gov (United States)

    Griffin, Eleanor R.; Perignon, Mariela C.; Friedman, Jonathan M.; Tucker, Gregory E.

    2014-01-01

    Distributions of woody vegetation on floodplain surfaces affect flood-flow erosion and deposition processes. A large flood along the lower Rio Puerco, New Mexico, in August 2006 caused extensive erosion in a reach that had been sprayed with herbicide in September 2003 for the purpose of saltcedar (Tamarix spp.) control. Large volumes of sediment, including a substantial fraction of sand, were delivered to the reach downstream, which had not been treated with herbicide. We applied physically based, one-dimensional models of flow and suspended-sediment transport to compute volume concentrations of sand in suspension in floodplain flow at a site within the sprayed reach and at a site downstream from the sprayed reach. We computed the effects of drag on woody stems in reducing the skin friction shear stress, velocity of flow, and suspended-sand transport from open paths into patches of dense stems. Total flow and suspended-sand fluxes were computed for each site using well-constrained flood-flow depths, water-surface slopes, and measured shrub characteristics. Results show that flow in open paths carried high concentrations of sand in suspension with nearly uniform vertical distributions. Drag on woody floodplain stems reduced skin friction shear stresses by two orders of magnitude, yet sufficient velocities were maintained to transport sand more than 50 m into fields of dense, free-surface-penetrating stems. An increase in shrub canopy extent from 31% in the sprayed reach site to 49% in the downstream site was found to account for 69% of the computed decrease in discharge between the two sites. The results demonstrate the need to compute the spatial distribution of skin friction shear stress in order to effectively compute suspended-sand transport and to predict the fate of sediment and contaminants carried in suspension during large floods.

  5. A comparative analysis of the diversity of woody vegetation in old-growth and secondary southern Appalachian cove forests

    Science.gov (United States)

    Lyle J. Guyon; Gary L. Rolfe; John M. Edgington; Guillermo A. Mendoza

    2003-01-01

    Characteristics of woody vegetation were compared across six different southern Appalachian cove forests. Trees greater than 6.35 cm dbh were point sampled and regeneration was tallied on 25 m² subplots at all study sites. Overstory composition and structure differed between secondary and old-growth sites, which were dominated by yellow-poplar and eastern...

  6. Impact of communal land use and conservation on woody vegetation structure in the Lowveld savannas of South Africa

    CSIR Research Space (South Africa)

    Wessels, Konrad J

    2011-01-01

    Full Text Available Millions of people rely on savannas for ecosystem services, such as the provision of grazing and fuel wood, so it is important to determine the extent to which utilization affects woody vegetation resources. Using airborne LiDAR from the Carnegie...

  7. The woody vegetation communities of the Hluhluwe-Corridor- Umfolozi Game Reserve Complex

    Directory of Open Access Journals (Sweden)

    A. Whateley

    1983-12-01

    Full Text Available Land units for the 900 km- Hluhluwe-Corridor-Umfolozi Game Reserve Complex in north eastern Natal were identified on aerial photographs. The physiognomy, dominants and description of the woody vegetation for each unit were identified during ground inspections and. where necessary, the point-centred quarter method was applied. Two forest, two riverine forest, ten woodland and two thicket communities were recognized. These communities are described according to their distribution, height and percentage frequency of the components in the different canopy strata. A map at a scale of 1:25 000 was also compiled. Some of these communities are compared with other similar woodlands previously described for Natal. In some communities the frequency of certain dominant canopy species in the under tree strata was extremely low and autecological research has been suggested.

  8. Vegetation types, dominant compositions, woody plant diversity and stand structure in Trishna Wildlife Sanctuary of Northeast India.

    Science.gov (United States)

    Majumdar, Koushik; Datta, B K

    2015-03-01

    Present study was carried out to assess the vegetation types, diversity and phytosociological status of woody plants in Trishna Wildlife Sanctuary of Tripura, Northeast India. Vegetation data was derived by 25 line transects (10 m wide and 500 m length, each 0.5 ha size). All woody species at >10 cm gbh (Girth at Breast Height) within each plots were measured and counted. A total of six forest types were classified by cluster analysis using Importance Value Index (IVI) of 289 woody species. Species diversity, forest structure and woody community associations were evaluated and discussed. One way ANOVA revealed significant differences in all species diversity measures and stand structure along the forest types. Distribution of stem density at ten different gbh classes showed reverse J-shaped curves. Population status of woody plants was also examined through grouping of all individuals into four population age stages viz. sapling ( or = 30 - 120 - 210 cm gbh) and old (> or =210 cm). To observe dominant composition and species population trend, IVI of top ten dominant species from all forest types were tabulated. The present study suggested that Trishna Wildlife Sanctuary is an important habitat in Tripura from floristic point of view and it should be conserved on priority basis for remaining wildlife endurances and monitor for forest livelihoods products for sustainable biodiversity conservation in this region.

  9. Riparian woody vegetation history in the campos region, southeastern South America, during two time windows: late Pleistocene and late Holocene

    Science.gov (United States)

    Mourelle, Dominique; Prieto, Aldo R.; García-Rodríguez, Felipe

    2017-07-01

    A detailed palynological record from Laguna Formosa (northeastern campos region, 31°S; 54°W) documents the dynamic balance between grasslands and riparian forests during the late Pleistocene (14,570 to 13,500 cal yr BP) and late Holocene (3280 cal yr BP to the present). Modern pollen-vegetation relationships and the woody pollen dispersal capacity analyses were used to improve the vegetation reconstruction. Grasslands were regionally dominant throughout the record. However, at 14,570 cal yr BP hydrophilous taxa reflect the development of riparian hydrophilous shrublands along freshwater bodies, promoting the fixation of the riverbanks, maintaining shallow, calm and clear water conditions under a relatively wet and not so cool climate. This is the first evidence of woody riparian vegetation development along freshwater bodies for the lowlands of the northern campos during the late glacial period. At 3280 cal yr BP riparian forests consisted of both hydrophilous and mesophilous woody taxa. Since 2270 cal yr BP woody vegetation gradually increased, accompanied by the incorporation of other taxa by 940 cal yr BP, and achieving a composition similar to that of the contemporary time at ca. 540 cal yr BP. The increased woody vegetation since ca. 2270 cal yr BP, and the more frequent and intense flooding events between 1800 and 1200 cal yr BP, could be related to higher precipitation over La Plata Drainage Basin, related with the high ENSO amplitude. In addition, pollen from taxa that currently no longer develops in the study area suggests connections between southern Brazil and Uruguay, and between the campos and the Chaco phytogeographic province.

  10. Multiscale influence of woody riparian vegetation on fluvial topography quantified with ground-based and airborne lidar

    Science.gov (United States)

    Bywater-Reyes, Sharon; Wilcox, Andrew C.; Diehl, Rebecca M.

    2017-06-01

    Coupling between riparian vegetation and river processes can result in the coevolution of plant communities and channel morphology. Quantifying biotic-abiotic interactions remains difficult because of the challenges in making and analyzing appropriately scaled observations. We measure the influence of woody vegetation on channel topography at the patch and reach scales in a sand bed, dryland river system (Santa Maria River, Arizona) with native Populus and invasive Tamarix. At the patch scale, we use ground-based lidar to relate plant morphology to "tail bars" formed in the lee of vegetation. We find vegetation roughness density (λf) to most influence tail-bar shape and size, suggesting coherent flow structures associated with roughness density are responsible for sediment deposition at this scale. Using airborne lidar, we test whether relationships between topography and vegetation morphology observed at the patch scale are persistent at the reach scale. We find that elevation of the channel (relative to the local mean) covaries with a metric of vegetation density, indicating analogous influences of vegetation density on topography across spatial scales. While these results are expected, our approach provides insight regarding interactions between woody riparian vegetation and channel topography at multiple scales, and a means to quantify such interactions for use in other field settings.

  11. The relationship between vegetation, slope stability and channel processes leading to the recruitment and mobilization of large woody debris

    Science.gov (United States)

    Gasser, Eric; Dorren, Luuk; Hübl, Johannes; Schwarz, Massimiliano

    2017-04-01

    Large woody debris fulfills important ecological functions in river systems, but it also increases the risk of damage during flood events in populated regions or along traffic routes. The mobilization and recruitment of "fresh" large woody debris has often been documented to be an important component of the total amount of wood transported during flood events in mountainous catchments. Therefore, research interest on recruitment, transport and deposition of large woody debris has arisen during the last decades. Although the main contributing processes are generally acknowledged and several modeling approaches have been proposed, less is known about the precise mechanisms behind recruitment and mobilization in mountainous catchments. Additionally, the role of vegetation in influencing the magnitude and the frequency of these mechanisms is often neglected or not considered in detail. Root reinforcement is particularly recognized to play an important role on bank erosion, bank failure and shallow landslides, but remains particularly difficult to quantify and implement in numerical models. This work presents a new modeling framework for simulating the effect of the spatio-temporal distribution of root reinforcement on bank erosion and slope stability in small mountainous catchments. The main objective of the work is to couple an existing shallow landslide model (SlideforMAP) with a bank erosion module to improve the prediction of large woody debris recruitment at mountainous catchment scales. Therefore the spatial structure of forest and its effect on root reinforcement, as obtained by remote sensing data, will be explicitly accounted for. Based on a first case study, we present results that help to quantify the effect of vegetation on the recruitment of „fresh" large woody debris and allow to detect potential contributing areas in small mountainous catchments. Further, suggestions on where forest management could improve overall slope and bank stability will be made

  12. Vegetative rhythm of some woody species; Rythmes de vegetation de quelques especes ligneuses

    Energy Technology Data Exchange (ETDEWEB)

    Gagnaire, J. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-07-01

    In laboratory conditions from march 1963 to april 1964, variations of calcium absorption by roots and translocation speed towards aerial parts of young norway spruce (Picea excelsa) in hydroponic growing, present fixed stages in a vegetative cycle: 1. from early april until end may a rapid rising of minerals from roots to young parts of the tree, associated with a redistribution of calcium formerly fixed in tissues; 2. in June-July, an equilibrium in mineral exchanges between the different parts of the tree; 3. from early august to end of October, a pre-dormancy phase marked by a slowing of translocation; 4. in november-december, an absolute dormancy period; 5. from January to march, a post-dormancy phase in which root absorption and translocation to aerial parts recover. In outdoors conditions and for a determined climate these stages start and end on dates linked to species and variety: - in Grenoble, absolute dormancy starts in September for thuyas, early October for maple-trees, middle October for norway spruce and novembers for poplars. (authors) [French] De mars 1963 a avril 1964, les variations de l'absorption radiculaire des sels de calcium et de leur vitesse de transport vers les parties aeriennes de jeunes epiceas (Picea excelsa) en culture hydroponique, au laboratoire, montrent cinq phases distinctes dans un cycle vegetatif: 1. du debut avril a la fin mai, une phase de montee rapide des sels mineraux depuis les racines jusqu'aux parties jeunes de l'arbre, associee a une redistribution des sels de calcium deja fixes dans les tissus; 2. en juin, juillet une phase d'equilibre dans les echanges mineraux entre les differentes parties de l'arbre; 3. du debut aout a la fin octobre une phase de pre-dormance caracterisee par un ralentissement progressif de la vitesse de transport; 4. en novembre et decembre, une phase de dormance absolue; 5. de janvier a mars une phase de post-dormance au cours de laquelle l'absorption radiculaire et

  13. DISTRIBUTION OF WOODY VEGETATION ON SODA WASTE DUMPS IN RELATION TO SPATIAL VARIATION IN SELECTED PARAMETERS OF THE MINERAL COVER

    Directory of Open Access Journals (Sweden)

    Ewelina Zając

    2016-11-01

    Full Text Available Development of woody plants in the course of succession on reclaimed soda waste dumps by use of mineral cover was analyzed. The spatial variation in the thickness and granulometric composition of the mineral cover was analysed by the Kriging method. The statistical measurements and geostatistical analysis were used to create maps showing areal variability for the parameters analysed. Analysis of the development of woody vegetation was based on field work and raster layers created on the basis of aerial photographs. No link was found between the parameters of the mineral cover and the distribution and development of spontaneous woody vegetation. The species composition in the study area is limited, and dominated by pioneer species, mainly the expansive black locust (Robinia pseudoacacia. Given that the soda waste disposal site is to be used as urban green spaces, the target ecosystem structure must be considered and a suitable course of action selected: further reclamation procedures improving substrate quality and enrichment of the species composition of the tree stand, or management involving sustaining the current state while controlling the course of natural succession of vegetation.

  14. Assessing woody vegetation trends in Sahelian drylands using MODIS based seasonal metrics

    DEFF Research Database (Denmark)

    Brandt, Martin Stefan; Hiernaux, Pierre; Rasmussen, Kjeld

    2016-01-01

    Woody plants play a major role for the resilience of drylands and in peoples' livelihoods. However, due to their scattered distribution, quantifying and monitoring woody cover over space and time is challenging. We develop a phenology driven model and train/validate MODIS (MCD43A4, 500 m) derived...

  15. Woody vegetation die off and regeneration in response to rainfall variability in the west African Sahel

    Science.gov (United States)

    Brandt, Martin; Tappan, G. Gray; Aziz Diouf, Abdoul; Beye, Gora; Mbow, Cheikh; Fensholt, Rasmus

    2017-01-01

    The greening in the Senegalese Sahel has been linked to an increase in net primary productivity, with significant long-term trends being closely related to the woody strata. This study investigates woody plant growth and mortality within greening areas in the pastoral areas of Senegal, and how these dynamics are linked to species diversity, climate, soil and human management. We analyse woody cover dynamics by means of multi-temporal and multi-scale Earth Observation, satellite based rainfall and in situ data sets covering the period 1994 to 2015. We find that favourable conditions (forest reserves, low human population density, sufficient rainfall) led to a rapid growth of Combretaceae and Balanites aegyptiaca between 2000 and 2013 with an average increase of 4% woody cover. However, the increasing dominance and low drought resistance of drought prone species bears the risk of substantial woody cover losses following drought years. This was observed in 2014–2015, with a die off of Guiera senegalensis in most places of the study area. We show that woody cover and woody cover trends are closely related to mean annual rainfall, but no clear relationship with rainfall trends was found over the entire study period. The observed spatial and temporal variation contrasts with the simplified labels of “greening” or “degradation”. While in principal a low woody plant diversity negatively impacts regional resilience, the Sahelian system is showing signs of resilience at decadal time scales through widespread increases in woody cover and high regeneration rates after periodic droughts. We have reaffirmed that the woody cover in Sahel responds to its inherent climatic variability and does not follow a linear trend.

  16. Woody Vegetation Die off and Regeneration in Response to Rainfall Variability in the West African Sahel

    Directory of Open Access Journals (Sweden)

    Martin Brandt

    2017-01-01

    Full Text Available The greening in the Senegalese Sahel has been linked to an increase in net primary productivity, with significant long-term trends being closely related to the woody strata. This study investigates woody plant growth and mortality within greening areas in the pastoral areas of Senegal, and how these dynamics are linked to species diversity, climate, soil and human management. We analyse woody cover dynamics by means of multi-temporal and multi-scale Earth Observation, satellite based rainfall and in situ data sets covering the period 1994 to 2015. We find that favourable conditions (forest reserves, low human population density, sufficient rainfall led to a rapid growth of Combretaceae and Balanites aegyptiaca between 2000 and 2013 with an average increase of 4% woody cover. However, the increasing dominance and low drought resistance of drought prone species bears the risk of substantial woody cover losses following drought years. This was observed in 2014–2015, with a die off of Guiera senegalensis in most places of the study area. We show that woody cover and woody cover trends are closely related to mean annual rainfall, but no clear relationship with rainfall trends was found over the entire study period. The observed spatial and temporal variation contrasts with the simplified labels of “greening” or “degradation”. While in principal a low woody plant diversity negatively impacts regional resilience, the Sahelian system is showing signs of resilience at decadal time scales through widespread increases in woody cover and high regeneration rates after periodic droughts. We have reaffirmed that the woody cover in Sahel responds to its inherent climatic variability and does not follow a linear trend.

  17. Altering recharge dynamics through woody vegetation removal: a study on the Carrizo-Wilcox aquifer of south Texas

    Science.gov (United States)

    Mattox, A. M.

    2011-12-01

    Grasslands in many semi-arid regions of the world have seen an expansion of woody vegetation over the past century and many now exist largely as woodlands or shrublands. This "woody encroachment" results in numerous changes to ecosystem function, including alteration of element and water cycles. As in many parts of the world, these shrublands in south Texas have been subjected to a variety of management practices intended to reduce woody vegetation and increase the dominance of herbaceous vegetation. In addition to the intended change in vegetation structure, this activity has the potential to affect hydrologic fluxes and potentially increase deep drainage through reduced transpiration and rooting depths. However, there is significant uncertainty about the hydrologic response of vegetation to woody vegetation removal. We report here the results of a large manipulative experiment designed to assess the effects of woody vegetation removal on soil moisture movement in the vadose zone in an area that serves as a recharge zone for an unconsolidated sediment aquifer (Carrizo-Wilcox). In this study woody vegetation has been removed using a mechanical method (roller chopping) as well as a mechanical and chemical method (chainsaw removal + stump herbicide). The treated plots are located on three different soil types that represent the range of soils typical in this area. A water balance approach is used to assess soil moisture fluxes and potential deep drainage. In this first year of the study we quantified ecological and edaphic components that have the greatest effect on deep drainage, namely rooting depth, soil texture and antecedent soil water conditions. Exceptionally dry conditions this year have provided a unique opportunity to understand plant soil water interactions in the critical zone given the strong soil moisture limitations observed in the surface soil horizons. Understanding these interactions across different plant communities and soil textures are the

  18. Assessing Woody Vegetation Trends in Sahelian Drylands Using MODIS Based Seasonal Metrics

    Science.gov (United States)

    Brandt, Martin; Hiernaux, Pierre; Rasmussen, Kjeld; Mbow, Cheikh; Kergoat, Laurent; Tagesson, Torbern; Ibrahim, Yahaya Z.; Wele, Abdoulaye; Tucker, Compton J.; Fensholt, Rasmus

    2016-01-01

    Woody plants play a major role for the resilience of drylands and in peoples' livelihoods. However, due to their scattered distribution, quantifying and monitoring woody cover over space and time is challenging. We develop a phenology driven model and train/validate MODIS (MCD43A4, 500m) derived metrics with 178 ground observations from Niger, Senegal and Mali to estimate woody cover trends from 2000 to 2014 over the entire Sahel. The annual woody cover estimation at 500 m scale is fairly accurate with an RMSE of 4.3 (woody cover %) and r(exp 2) = 0.74. Over the 15 year period we observed an average increase of 1.7 (+/- 5.0) woody cover (%) with large spatial differences: No clear change can be observed in densely populated areas (0.2 +/- 4.2), whereas a positive change is seen in sparsely populated areas (2.1 +/- 5.2). Woody cover is generally stable in cropland areas (0.9 +/- 4.6), reflecting the protective management of parkland trees by the farmers. Positive changes are observed in savannas (2.5 +/- 5.4) and woodland areas (3.9 +/- 7.3). The major pattern of woody cover change reveals strong increases in the sparsely populated Sahel zones of eastern Senegal, western Mali and central Chad, but a decreasing trend is observed in the densely populated western parts of Senegal, northern Nigeria, Sudan and southwestern Niger. This decrease is often local and limited to woodlands, being an indication of ongoing expansion of cultivated areas and selective logging.We show that an overall positive trend is found in areas of low anthropogenic pressure demonstrating the potential of these ecosystems to provide services such as carbon storage, if not over-utilized. Taken together, our results provide an unprecedented synthesis of woody cover dynamics in theSahel, and point to land use and human population density as important drivers, however only partially and locally offsetting a general post-drought increase.

  19. Trophic ecology of Lepidoptera larvae associated with woody vegetation in a savanna ecosystem

    CSIR Research Space (South Africa)

    Scholtz, CH

    1982-06-01

    Full Text Available This study represents a quantitative survey of a Lepidoptera community and deals with the trophic ecology of the 27 species of foliage-feeding Lepidoptera on the eight dominant woody plants in the Burkea africana-Eragrostis pallens savanna...

  20. Comparison of {sup 226}Ra nuclide from soil by three woody species Betula pendula, Sambucus nigra and Alnus glutinosa during the vegetation period

    Energy Technology Data Exchange (ETDEWEB)

    Soudek, Petr; Petrova, Sarka; Benesova, Dagmar [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR and Crop Research Institute, Rozvojova 263, 165 02 Prague 6 (Czech Republic); Tykva, Richard [Department of Radioisotopes, Institute of Organic Chemistry and Biochemistry AS CR, Flemingovo nam. 2, 166 10 Prague 6 (Czech Republic); Vankova, Radomira [Laboratory of Hormonal Regulations in Plants, Institute of Experimental Botany AS CR, Rozvojova 263, 165 02 Prague 6 (Czech Republic); Vanek, Tomas [Laboratory of Plant Biotechnologies, Joint Laboratory of Institute of Experimental Botany AS CR and Crop Research Institute, Rozvojova 263, 165 02 Prague 6 (Czech Republic)], E-mail: vanek@ueb.cas.cz

    2007-09-15

    The uptake of {sup 226}Ra from the contaminated soil was compared in three woody species: alder (Alnus glutinosa), birch (Betula pendula) and elder (Sambucus nigra). The {sup 226}Ra activities increased during the vegetation periods (in 2003, 2004 and 2005) both in the leaves and flowers + seeds. The highest accumulation was found in birch, reaching 0.41 Bq/g DW in the leaves (at the end of the vegetation period in 2003). The lowest {sup 226}Ra accumulation was determined in alder. The extent of {sup 226}Ra accumulation in the leaves of woody species demonstrates that these pioneer woody species can be used as remediation alternative to the use of herbs, provided that the removal of fallen leaves could be achieved in the end of vegetation period.

  1. The impact of an increasing elephant population on the woody vegetation in southern Sabi Sand Wildtuin, South Africa

    Directory of Open Access Journals (Sweden)

    Kay Hiscocks

    1999-02-01

    Full Text Available In 1961, a fence was erected between privately owned Sabi Sand Wildtuin (SSW and the Kruger National Park (KNP, which largely prevented elephants entering the SSW. In 1993, the fence was removed. This lead to a rapid influx of elephants into the SSW during the winter months, most of which move back into the KNP during the wet summer season. In 1993, the SSW elephant population was 1/1045 ha but increased to 1/305.8 ha in 1996. It more than doubled to 1/146 ha in 1998. This study was undertaken on the property Kingston, in southern SSW, to assess the impact of elephants on woody vegetation and determine why they show seasonal dietary preferences for specific tree parts. Vegetation utilisation was recorded on a five kilometer transect of vehicle track in 1996 and repeated in 1998. From the transect, species density was calculated for those trees impacted on. Trees that had been newly bark stripped were recorded in 1996 and 1998. Cambium samples were collected in summer and winter from eight tree species. Field observations of elephants impacting on woody vegetation augmented the data base. Transect analysis showed a strong correlation between tree utilisation and density. The most visual damage was of Combretum apiculatum, Acacia burkei, Pterocarpus rotundifolius and Grewia species. Tree damage increased by 73 from 1996 to 1998. Significantly higher levels of nitrogen, sodium and magnesium were found in the species most regularly bark stripped. Bull elephants were responsible for 94 of the trees seen uprooted. The results suggested that SSW can sustain the present elephant population, but further influx at the present rate of increase, will have a negative impact on the reserve.

  2. Land Use and Land Cover Change, and Woody Vegetation Diversity in Human Driven Landscape of Gilgel Tekeze Catchment, Northern Ethiopia

    Directory of Open Access Journals (Sweden)

    Samuale Tesfaye

    2014-01-01

    Full Text Available Land use and land cover (LULC change through inappropriate agricultural practices and high human and livestock population pressure have led to severe land degradation in the Ethiopian highlands. This has led to further degradation such as biodiversity loss, deforestation, and soil erosion. The study examined woody vegetation diversity status and the impact of drivers of change across different LULC types and agroecological zones in Gilgel Tekeze catchment, northern Ethiopian highlands. LULC dynamics were assessed using GIS techniques on 1976, 1986, and 2008 satellite images. Vegetation data were collected from 135 sample plots (20 m × 20 m from five LULC types, namely, forest, shrub-bush, grazing, settlement, and cultivated land, in the three agroecological zones; Kolla, Weyna-Dega, and Dega. Differences in vegetation structure and composition and their relationship to agroecological zones were tested using two-way ANOVA and PCA technique. The results show that vegetation structure and composition significantly differed across all LULC types in different agroecological zones particularly in sapling density, tree height, and shrub height and in each agroecological zone between forest land, shrub-bush land, and settlement area. Overall, Weyna-Dega agroecological zone and the shrub-bush land had more structural and compositional diversity than the other agroecological zones and LULC types.

  3. Can antibrowsing defense regulate the spread of woody vegetation in arctic tundra?

    Science.gov (United States)

    Bryant, John P.; Joly, Kyle; Chapin, F. Stuart; DeAngelis, Donald L.; Kielland, Knut

    2014-01-01

    Global climate warming is projected to promote the increase of woody plants, especially shrubs, in arctic tundra. Many factors may affect the extent of this increase, including browsing by mammals. We hypothesize that across the Arctic the effect of browsing will vary because of regional variation in antibrowsing chemical defense. Using birch (Betula) as a case study, we propose that browsing is unlikely to retard birch expansion in the region extending eastward from the Lena River in central Siberia across Beringia and the continental tundra of central and eastern Canada where the more effectively defended resin birches predominate. Browsing is more likely to retard birch expansion in tundra west of the Lena to Fennoscandia, Iceland, Greenland and South Baffin Island where the less effectively defended non-resin birches predominate. Evidence from the literature supports this hypothesis. We further suggest that the effect of warming on the supply of plant-available nitrogen will not significantly change either this pan-Arctic pattern of variation in antibrowsing defense or the resultant effect that browsing has on birch expansion in tundra. However, within central and east Beringia warming-caused increases in plant-available nitrogen combined with wildfire could initiate amplifying feedback loops that could accelerate shrubification of tundra by the more effectively defended resin birches. This accelerated shrubification of tundra by resin birch, if extensive, could reduce the food supply of caribou causing population declines. We conclude with a brief discussion of modeling methods that show promise in projecting invasion of tundra by woody plants.

  4. Woody plants diversity and type of vegetation in non cultivated plain of Moutourwa, Far-North, Cameroon

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    Gilbert Todou

    2016-12-01

    Full Text Available In order to valorize the wild vegetal resources for the efficient conservation and sustainable use in sahelo-sudanian zone in Cameroon, a study of non cultivated plain of Moutourwa was carry out to assess the floristic richness, the specific diversity and the type of vegetation. The inventory of all trees and shrubs (dbh ? 2.5 cm and the determination of the vegetation cover were done in five linear transects (20 m × 1000 m. In total, 27 families, 54 genera and 75 species were found. Caesalpinaceae is the most abundant family that relative abundance (pi*100 is 34.41%, the most abundant genus was Piliostigma (pi*100 = 30.66% and the most represented species was Piliostigma reticulatum (pi*100 = 29.56%; D = 53.6 stems/ha. The Simpson index (E= 0.89, the Shannon index (H= 3.2 and the equitability index of Pielou (J= 0.74 indicated that there were moderate diversity with more or less equitable species. The wild fruits species were numerous (pi*100 = 32.76%; D = 59.7 stems/ha. A. senegalensis is was the most represented (pi*100 = 9.04 ; D = 16.4 followed by Hexalobus monopetalus (pi*100 = 5.16 ; D = 9.4 and Balanites aegyptiaca (pi*100 = 3.69 ; D = 6.7. These results contribute efficaciously to valorize the wild vegetal resources for efficient conservation and sustainable use. Keywords: Woody plants diversity, conservation, sustainable use, sahelo-sudanian, Moutourwa

  5. Long-term changes in the woody vegetation of the Kruger National Park, with special reference to the effects of elephants and fire

    Directory of Open Access Journals (Sweden)

    W.S.W. Trollope

    1998-02-01

    Full Text Available As part of the investigation reviewing the South African National Parks policy on the management of elephants in the Kruger National Park in South Africa it was decided to assess the current density and structural diversity of the woody vegetation in the park as it is affected by elephants and fire. The management policy used till recently, limited the population to approximately 7000 elephants, based on a conclusion that 6000 elephants (1 per 1.94 km2 was the highest number of elephants that could be carried in the Kruger National Park. The inclusion of the effects and interaction of fire in the investigation arises from the general recognition that elephants and fire can have a highly significant impact on the species and structural diversity of tree and shrub vegetation in African savannas. In the absence of quantitative data describing the condition of the woody vegetation in the Kruger National Park, subjective comparisons of changes in the density of large trees were made for the periods 1940 vs 1960 and 1960 vs 1986/89 using aerial photographs based on four of the major vegetation landscape units in the park. The results indicate that in the vegetation landscapes in areas with granitic soils there were no significant changes in the density of large trees between 1940 vs 1960 whereas a moderate decline occurred in the vegetation in the areas with basaltic soils. Conversely during the period 1960 to 1986/89 there was a dramatic decline in the density of large trees in all four major vegetation landscape units. On-site inspections and botanical surveys suggest that the decline in the density of large trees is the result of the effects of the interaction of elephants and fire. This had arisen because during the period 1960 to 1986/89 systematic burning programs had been introduced at the same time as elephant numbers had risen sharply. The results presented suggest that the changes in the woody vegetation do not involve a decrease in species

  6. Comparison of the current state of non-forest woody vegetation in two contrasted case study areas in Central Europe

    Directory of Open Access Journals (Sweden)

    Demková Katarína

    2017-03-01

    Full Text Available Non-forest woody vegetation (NFWV, as a part of green infrastructure, has gained a great deal of attention in recent years. Despite its importance in many productive and non-productive functions, an inventory (collection of quantitative and qualitative data on a national or even on a local level is not available in many European countries. The main aim of this study is to carry out a comparison of two study areas (lowland and upland from the perspective of the current state of NFWV. We investigate qualitative attributes of NFWV, its relation to environmental conditions and its spatial pattern. After manual vectorization of orthophotos, qualitative data were collected in the field. Using statistical and landscape-ecological methods, the relation between NFWV and environmental conditions, as well as its spatial pattern were assessed. Substantial differences in character and in the spatial pattern of NFWV were identified between the study areas. NFWV in the upland area has a higher proportion (2.6% than in lowland study area (1.5%, and it also has a more heterogeneous spatial structure. Statistical analysis points to a significant relation between the NFWV and land cover types in both study areas. A significant relation between NFWV and soil types was identified only in the upland area, however, while an association with potential natural vegetation was found in the lowland study area.

  7. Recovery of South African fynbos vegetation following alien woody plant clearing and fire: implications for restoration

    CSIR Research Space (South Africa)

    Holmes, PM

    2000-12-01

    Full Text Available The recovery of fynbos vegetation after invasion by dense stands of alien trees, and clearing by either 'burn standing’,’ fell and burn', or 'fell, remove and burn' treatments, was investigated in two watersheds in the Western Cape Province, South...

  8. Dynamics of woody vegetation in a semi-arid savanna, with a focus ...

    African Journals Online (AJOL)

    The effects of soil type and grazing on the tree:grass ratio in encroached Acacia mellifera-dominated savannas in the Northern Cape, South Africa, were investigated by means of vegetation classification and analyses of sequential aerial photographs. Acacia mellifera never occurred on clay pans, and in low numbers only in ...

  9. The Impact of Elephants on the Woody Vegetation of Mole National ...

    African Journals Online (AJOL)

    Elephant damage on trees ≥ 2 m tall involving uprooting and main trunk breakage, as well as debarking was assessed in the upper- to middle-slope and lower-slope savannas of the elephantoccupied section of Mole National Park. Elephant damage on trees in either vegetation type was light, but varied among the ...

  10. Long term effects of fire frequency and season on the woody vegetation dynamics of the Sclerocarya birrea/Acacia nigrescens savanna of the Kruger National Park

    Directory of Open Access Journals (Sweden)

    B.W. Enslin

    2000-07-01

    Full Text Available A lack of knowledge together with vacillating fire management approaches in the Kruger National Park until the mid 1950s, gave rise to a long term fire research experiment aimed at shedding light on savanna responses to various combinations of fire fre- quencies and seasons. This trial was laid out in 1954 in four of the six major vegetation zones of the park. With the future of the experiment now being reconsidered, full scale vegetation surveys have been conducted on all the plots and compared to the surveys done in 1954. This paper examines the woody vegetation responses to fourteen fire treatments in the Knobthorn/Marula savanna. Parameters of interest were woody species composition responses, together with tree & shrub density and structural changes. The results indicate that no significant changes in woody species had occurred for the peri- od 1954 vs 1998, while density decreased on biennial and increased on triennial treatments. The proportion of single stemmed plants increased over the period. Season of burn has a marked effect on structure, with April and August burns giving rise to the largest basal areas but the lowest heights. Environmental parameters such as climate, varying herbivory and differing soils, and their respective interactions on vegetation morphology, together with fire behaviour, further influenced results.

  11. Ecological and Geochemical Assessment of Woody Vegetation in Tungsten-Molybdenum Mining Area (Buryat Republic, Russia)

    Science.gov (United States)

    Kasimov, N. S.; Kosheleva, N. E.; Timofeev, I. V.

    2016-08-01

    Biogeochemical studies performed in the impact zone of the Dzhida tungsten- molybdenum mining and processing enterprise in Zakamensk (Buryat Republic, Russia) in 2013 showed that the needles and bark of Lárix sibírica Ledeb. and the leaves and bark of Bétula platyphýlla Sukacs are characterized by certain changes in their trace element (TE) composition. The total index of the biogeochemical transformation Z v which sums all the positive and negative deviations of TE contents from the background values for larch and birch in the city averaged 95 and 46 for their assimilating organs and 30 and 25 for their perennial organs, respectively. This was caused by the increased uptake of W, Mo, V, Pb, Bi, Cd, and Co in the city. The close correlation between TE concentrations in soils and plants was observed for the elements of the strong and moderate biological capturing, including cationic Cu, Zn, Sr, Cd, and Ba and anions of the ore elements W and Mo and the associated Bi. The most intensive TE accumulation was found in the larch needles due to the wax layer which firmly fixes the dust enriched with TEs. Indication of the ecological state of urban woody plants revealed that their organs contain the increased concentrations of Pb and Fe and suffer from the Mn deficiency, which attests to disturbance of photosynthetic processes, most pronounced in the residential area. Birch leaves are characterized by a very low Cu/Zn ratio which detects the imbalance of these elements participating in the synthesis of enzymes.

  12. Woody vegetation cover monitoring with multi-temporal Landsat data and Random Forests: the case of the Northwest Province (South Africa)

    Science.gov (United States)

    Symeonakis, Elias; Higginbottom, Thomas; Petroulaki, Kyriaki

    2016-04-01

    Land degradation and desertification (LDD) are serious global threats to humans and the environment. Globally, 10-20% of drylands and 24% of the world's productive lands are potentially degraded, which affects 1.5 billion people and reduces GDP by €3.4 billion. In Africa, LDD processes affect up to a third of savannahs, leading to a decline in the ecosystem services provided to some of the continent's poorest and most vulnerable communities. Indirectly, LDD can be monitored using relevant indicators. The encroachment of woody plants into grasslands, and the subsequent conversion of savannahs and open woodlands into shrublands, has attracted a lot of attention over the last decades and has been identified as an indicator of LDD. According to some assessments, bush encroachment has rendered 1.1 million ha of South African savanna unusable, threatens another 27 million ha (~17% of the country), and has reduced the grazing capacity throughout the region by up to 50%. Mapping woody cover encroachment over large areas can only be effectively achieved using remote sensing data and techniques. The longest continuously operating Earth-observation program, the Landsat series, is now freely-available as an atmospherically corrected, cloud masked surface reflectance product. The availability and length of the Landsat archive is thus an unparalleled Earth-observation resource, particularly for long-term change detection and monitoring. Here, we map and monitor woody vegetation cover in the Northwest Province of South Africa, a mosaic of 12 Landsat scenes that expands over more than 100,000km2. We employ a multi-temporal approach with dry-season TM, ETM+ and OLI data from 15 epochs between 1989 to 2015. We use 0.5m-pixel colour aerial photography to collect >15,000 samples for training and validating a Random Forest model to map woody cover, grasses, crops, urban and bare areas. High classification accuracies are achieved, especially so for the two cover types indirectly

  13. A New Method to Define the VI-Ts Diagram Using Subpixel Vegetation and Soil Information: A Case Study over a Semiarid Agricultural Region in the North China Plain.

    Science.gov (United States)

    Sun, Zhigang; Wang, Qinxue; Matsushita, Bunkei; Fukushima, Takehiko; Ouyang, Zhu; Watanabe, Masataka

    2008-10-07

    The VI-Ts diagram determined by the scatter points of the vegetation index (VI) and surface temperature (Ts) has been widely applied in land surface studies. In the VI-Ts diagram, dry point is defined as a pixel with maximum Ts and minimum VI, while wet point is defined as a pixel with minimum Ts and maximum VI. If both dry and wet points can be obtained simultaneously, a triangular VI-Ts diagram can be readily defined. However, traditional methods cannot define an ideal VI-Ts diagram if there are no full ranges of land surface moisture and VI, such as during rainy season or in a period with a narrow VI range. In this study, a new method was proposed to define the VI-Ts diagram based on the subpixel vegetation and soil information, which was independent of the full ranges of land surface moisture and VI. In this method, a simple approach was firstly proposed to decompose Ts of a given pixel into two components, the surface temperatures of soil (T soil ) and vegetation (T veg ), by means of Ts and VI information of neighboring pixels. The minimum T veg and maximum T soil were then used to determine the wet and dry points respectively within a given sampling window. This method was tested over a 30 km × 30 km semiarid agricultural area in the North China Plain through 2003 using Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) and MODerate-resolution Imaging Spectroradiometer (MODIS) data. The wet and dry points obtained from our proposed method and from a traditional method were compared with those obtained from ground data within the sampling window with the 30 km × 30 km size. Results show that T soil and T veg can be obtained with acceptable accuracies, and that our proposed method can define reasonable VI-Ts diagrams over a semiarid agricultural region throughout the whole year, even for both cases of rainy season and narrow range of VI.

  14. A New Method to Define the VI-Ts Diagram Using Subpixel Vegetation and Soil Information: A Case Study over a Semiarid Agricultural Region in the North China Plain

    Directory of Open Access Journals (Sweden)

    Masataka Watanabe

    2008-10-01

    Full Text Available The VI-Ts diagram determined by the scatter points of the vegetation index (VI and surface temperature (Ts has been widely applied in land surface studies. In the VI-Ts diagram, dry point is defined as a pixel with maximum Ts and minimum VI, while wet point is defined as a pixel with minimum Ts and maximum VI. If both dry and wet points can be obtained simultaneously, a triangular VI-Ts diagram can be readily defined. However, traditional methods cannot define an ideal VI-Ts diagram if there are no full ranges of land surface moisture and VI, such as during rainy season or in a period with a narrow VI range. In this study, a new method was proposed to define the VI-Ts diagram based on the subpixel vegetation and soil information, which was independent of the full ranges of land surface moisture and VI. In this method, a simple approach was firstly proposed to decompose Ts of a given pixel into two components, the surface temperatures of soil (Tsoil and vegetation (Tveg, by means of Ts and VI information of neighboring pixels. The minimum Tveg and maximum Tsoil were then used to determine the wet and dry points respectively within a given sampling window. This method was tested over a 30 km × 30 km semiarid agricultural area in the North China Plain through 2003 using Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER and MODerate-resolution Imaging Spectroradiometer (MODIS data. The wet and dry points obtained from our proposed method and from a traditional method were compared with those obtained from ground data within the sampling window with the 30 km × 30 km size. Results show that Tsoil and Tveg can be obtained with acceptable accuracies, and that our proposed method can define reasonable VI-Ts diagrams over a semiarid agricultural region throughout the whole year, even for both cases of rainy season and narrow range of VI.

  15. Post-fire dynamics of the woody vegetation of a savanna forest (Cerradão in the Cerrado-Amazon transition zone

    Directory of Open Access Journals (Sweden)

    Simone Matias Reis

    2015-09-01

    Full Text Available ABSTRACTFire can change the species composition, diversity, and structure of savanna vegetation, thus altering growth and mortality rates. Such changes in the woody vegetation of burned savanna forest were evaluated over four years in comparison to unburned savanna forest. All woody plants with a diameter at breast height > 10 cm were measured in 100 permanent plots. Six months later, 38 of these plots were burned. Three and a half years later, all surviving individuals were re-sampled. Species richness, diversity, and the number of individuals did not change in the burned plots, although they had significantly higher (p < 0.05 increases in basal area and mortality rates (5.1% year-1 than the unburned plots (3.0% year-1.Tachigali vulgarishad the greatest post-fire increase in basal area (53%. The results indicate that fire alters the dynamics and structure of the savanna forest, excluding the less fire-tolerant species and smaller individuals (? 15cm. Tachigali vulgaris is a key species for the recovery of savanna forest biomass due to its considerable post-fire gains in basal area, at least over the short term due to its short life cycle. It follows that frequent burning of savanna forest would result in a marked change in the species composition and structure of its woody vegetation.

  16. Forested floristic quality index: An assessment tool for forested wetland habitats using the quality and quantity of woody vegetation at Coastwide Reference Monitoring System (CRMS) vegetation monitoring stations

    Science.gov (United States)

    Wood, William B.; Shaffer, Gary P.; Visser, Jenneke M.; Krauss, Ken W.; Piazza, Sarai C.; Sharp, Leigh Anne; Cretini, Kari F.

    2017-02-08

    overstory and health of the herbaceous community beneath it because of resource competition (for example, light) and differing environmental preferences between the two communities. The herbaceous layer vegetation responds rapidly to basic environmental factors such as flooding, salinity, and nutrients and can offer insight into the sustainability of swamps on a temporal scale shorter than tha of the slowly growing woody vegetation.The FFQI will be available via the CRMS spatial viewer (http://lacoast.gov/crms2/home.aspx), and a new score will be calculated annually for each CRMS forested wetland site as data are collected to establish trends, to compare among sites, and to evaluate specific restoration projects when applicable. The FFQI will identify forested wetland areas in need of restoration and conservation and will help define targets and trajectories for restoration planning.

  17. When Winners Become Losers: Predicted Nonlinear Responses of Arctic Birds to Increasing Woody Vegetation.

    Directory of Open Access Journals (Sweden)

    Sarah J Thompson

    Full Text Available Climate change is facilitating rapid changes in the composition and distribution of vegetation at northern latitudes, raising questions about the responses of wildlife that rely on arctic ecosystems. One widely observed change occurring in arctic tundra ecosystems is an increasing dominance of deciduous shrub vegetation. Our goals were to examine the tolerance of arctic-nesting bird species to existing gradients of vegetation along the boreal forest-tundra ecotone, to predict the abundance of species across different heights and densities of shrubs, and to identify species that will be most or least responsive to ongoing expansion of shrubs in tundra ecosystems. We conducted 1,208 point counts on 12 study blocks from 2012-2014 in northwestern Alaska, using repeated surveys to account for imperfect detection of birds. We considered the importance of shrub height, density of low and tall shrubs (i.e. shrubs >0.5 m tall, percent of ground cover attributed to shrubs (including dwarf shrubs <0.5 m tall, and percent of herbaceous plant cover in predicting bird abundance. Among 17 species considered, only gray-cheeked thrush (Catharus minimus abundance was associated with the highest values of all shrub metrics in its top predictive model. All other species either declined in abundance in response to one or more shrub metrics or reached a threshold where further increases in shrubs did not contribute to greater abundance. In many instances the relationship between avian abundance and shrubs was nonlinear, with predicted abundance peaking at moderate values of the covariate, then declining at high values. In particular, a large number of species were responsive to increasing values of average shrub height with six species having highest abundance at near-zero values of shrub height and abundance of four other species decreasing once heights reached moderate values (≤ 33 cm. Our findings suggest that increases in shrub cover and density will negatively

  18. In vitro culture used for woody fern Cyathea australis (R. Br. domin vegetative propagation

    Directory of Open Access Journals (Sweden)

    Katarzyna Goller

    2014-01-01

    Full Text Available Experiments have been carried out on vegetative multiplication of Cyathea australis. Cultures were initiated from spores collected from sporangium of mature fronds. Spores were sterilized in 3% chloramine with Tween and sown on Anderson (1984 medium supplemented with 80.0 mg/l of Ads and solidified by 8.0 g/l of agar. After three months of spore germination overgrowth of prothallia was observed. Multiplication of prothallia was stimulated by MS (1962 medium supplemented with 0.25 mg/l BAP, 0.50 mg/l IBA, 0.50 mg/l IAA, 1.00 mg/l GA3, 40.00 mg/l Ads and sucrose 30.0 g/l. Small drops of water were placed on the basal part of gametophyte in order to help ovary fertilization. After the next few weeks the first very fragile, small and green crosier emerged from the base of gametophyte. Perlite culture stimulated root formation and plant hardening to soil conditions.

  19. Effects of soil and space on the woody species composition and vegetation structure of three Cerrado phytophysiognomies in the Cerrado-Amazon transition.

    Science.gov (United States)

    Maracahipes-Santos, L; Lenza, E; Santos, J O; Mews, H A; Oliveira, B

    2017-11-01

    The Cerrado Biome is considered one of the world's biodiversity hotspots because of its rich biodiversity, the high level of endemism and the increasing threat. The Cerrado is composed by a mosaic of different vegetation types, including physiognomies that vary from grasslands (campo limpo) to savannas (typical cerrado or cerrado sensu stricto) and cerrado woodlands (cerradão). However, the factors that determine the composition of the Cerrado's flora and the structure of the physiognomies that compose this biome are still poorly understood. Here, we investigate the influence of the chemical and granulometric properties of the soil and the effect of geographic distance on the occurrence and abundance of woody species in three Cerrado phytophysiognomies - cerrado woodland (cerradão), dense cerrado savanna and typical cerrado savanna - in the Cerrado-Amazon transition. We tested the hypothesis that the edaphic characteristics and geographic space determine the species composition and the structure of the woody vegetation of these three phytophysiognomies. We demonstrate that the dissimilarities in the structure and composition of the three sites were determined more by space (13% of explanation) than edaphic properties (1%), but primarily by the interaction between these two factors (26%). We conclude that, in situations where the chemical and granulometric properties of the soil are relatively homogeneous, as we found in the present study, geographic distance between sites has a greater influence than variation in the substrate's properties on modelling the occurrence and abundance of the woody plant species in the Cerrado.

  20. Large-scale carbon stock assessment of woody vegetation in tropical dry deciduous forest of Sathanur reserve forest, Eastern Ghats, India.

    Science.gov (United States)

    Gandhi, Durai Sanjay; Sundarapandian, Somaiah

    2017-04-01

    Tropical dry forests are one of the most widely distributed ecosystems in tropics, which remain neglected in research, especially in the Eastern Ghats. Therefore, the present study was aimed to quantify the carbon storage in woody vegetation (trees and lianas) on large scale (30, 1 ha plots) in the dry deciduous forest of Sathanur reserve forest of Eastern Ghats. Biomass of adult (≥10 cm DBH) trees was estimated by species-specific allometric equations using diameter and wood density of species whereas in juvenile tree population and lianas, their respective general allometric equations were used to estimate the biomass. The fractional value 0.4453 was used to convert dry biomass into carbon in woody vegetation of tropical dry forest. The mean aboveground biomass value of juvenile tree population was 1.86 Mg/ha. The aboveground biomass of adult trees ranged from 64.81 to 624.96 Mg/ha with a mean of 245.90 Mg/ha. The mean aboveground biomass value of lianas was 7.98 Mg/ha. The total biomass of woody vegetation (adult trees + juvenile population of trees + lianas) ranged from 85.02 to 723.46 Mg/ha, with a mean value of 295.04 Mg/ha. Total carbon accumulated in woody vegetation in tropical dry deciduous forest ranged from 37.86 to 322.16 Mg/ha with a mean value of 131.38 Mg/ha. Adult trees accumulated 94.81% of woody biomass carbon followed by lianas (3.99%) and juvenile population of trees (1.20%). Albizia amara has the greatest biomass and carbon stock (58.31%) among trees except for two plots (24 and 25) where Chloroxylon swietenia contributed more to biomass and carbon stock. Similarly, Albizia amara (52.4%) showed greater carbon storage in juvenile population of trees followed by Chloroxylon swietenia (21.9%). Pterolobium hexapetalum (38.86%) showed a greater accumulation of carbon in liana species followed by Combretum albidum (33.04%). Even though, all the study plots are located within 10 km radius, they show a significant spatial variation among

  1. ANALYSIS OF THE WOODY VEGETATION DYNAMICS IN THE AREA OF TREE LINE ECOTONE ON THE BASIS OF PHOTO MONITORING DATA AND USING GIS

    Directory of Open Access Journals (Sweden)

    A. P. Mikhailovich

    2016-01-01

    Full Text Available A method of processing and presentation of the repeated landscape photographs for analysis of spatio-temporal dynamics of woody vegetation in tree line ecotone the Polar Urals (mountain Rai-Iz was developed. It is intended to solve problems with the use of such photographs so as to help the researcher to gain an integral representation of the space under study, obtain additional information about the region of interest, create and update annotation to photographs, and develop thematic maps using repeated landscape photography.

  2. Effects of repeated burning on woody vegetation structure and composition in a semi-arid southern African savanna

    NARCIS (Netherlands)

    Gandiwa, E.

    2011-01-01

    The objective of this study was to investigate the effects of repeated dry season annual hot fires on woody plants in a semiarid southern African savanna in Zimbabwe. Parts of the National University of Science and Technology (NUST) research fields in Bulawayo, Zimbabwe have been burnt annually in

  3. Conundrums in mixed woody-herbaceous plant systems

    CSIR Research Space (South Africa)

    House, JI

    2003-11-01

    Full Text Available stable and persistent under a particular set of conditions? The net primary productivity (NPP) conundrum. How does NPP of the woody vegetation, the herbaceous vegetation, and the total ecosystem (woody + herbaceous) change with changes in the tree...

  4. Quantifying Savanna Woody Cover in the Field and on Historical ...

    African Journals Online (AJOL)

    The proliferation of woody vegetation on open grass savannas constitutes degradation in rangeland quality. Historical high spatial resolution satellite imagery in archive provides possibilities for assessing increase in woody vegetation cover on the rangelands. This paper examines the quantification of woody vegetation in ...

  5. Spatial scaling of net primary productivity using subpixel landcover information

    Science.gov (United States)

    Chen, X. F.; Chen, Jing M.; Ju, Wei M.; Ren, L. L.

    2008-10-01

    Gridding the land surface into coarse homogeneous pixels may cause important biases on ecosystem model estimations of carbon budget components at local, regional and global scales. These biases result from overlooking subpixel variability of land surface characteristics. Vegetation heterogeneity is an important factor introducing biases in regional ecological modeling, especially when the modeling is made on large grids. This study suggests a simple algorithm that uses subpixel information on the spatial variability of land cover type to correct net primary productivity (NPP) estimates, made at coarse spatial resolutions where the land surface is considered as homogeneous within each pixel. The algorithm operates in such a way that NPP obtained from calculations made at coarse spatial resolutions are multiplied by simple functions that attempt to reproduce the effects of subpixel variability of land cover type on NPP. Its application to a carbon-hydrology coupled model(BEPS-TerrainLab model) estimates made at a 1-km resolution over a watershed (named Baohe River Basin) located in the southwestern part of Qinling Mountains, Shaanxi Province, China, improved estimates of average NPP as well as its spatial variability.

  6. Dynamic response of woody vegetation on fencing protection in semi-arid areas; Case study: Pilot exclosure on the Firmihin Plateau, Socotra Island.

    Science.gov (United States)

    Habrova, Hana; Pavlis, Jindrich

    2017-02-01

    Woody vegetation dynamics and Dracaena cinnabari regeneration have been studied for five years in the conditions of Socotra Island. Woody plants were measured regularly inside and outside the exclosure area, and the growth and survival of D. cinnabari seedlings were observed. In the exclosure of about 1000 m(2) a total of 49 species were identified, including 23 endemics, growing in the average density of 3.82 specimens per m(2). The fenced area was overgrown relatively rapidly by dense grass cover - reaching approx. 2.7 t/ha. Species growth dynamics inside and outside the exclosure shows that grazing had a marked impact, leading to the elimination of trees and shrubs. All grazed species grew noticeably in the exclosure, in the average of 50 cm in 5 years. D. cinnabari as the dominant flagship species of Socotra has been studied with regards to regeneration dynamics. Observations indicate that probability of its seedlings survival increases with their age. No seedlings germinated from the seeds sown in the experiment, however, outplanted seedlings performed relatively well. Field observations show that D. cinnabari seed germination is triggered when the seed reaches a protected micro-habitat with a developed humus layer and high relative humidity in the soil lasts for at least two days.

  7. Study of floristic diversity and the structural dynamics of some species providers of non woody forest products in the vegetable formations of the Centre East of Burkina Faso.

    Science.gov (United States)

    Ky, J M K; Gnoula, C; Zerbo, P; Simpore, J; Nikiema, J B; Canini, A; Millogo-Rasolodimby, J

    2009-07-15

    The goal of this study is to contribute to a better knowledge of certain species providing Non Woody Forest Products (NWFP) in the Centre East of Burkina Faso. This study aims to determine the state of the resources in Vitellaria paradoxa, Balanites aegyptiaca, Tamarindus indica and Lannea microcarpa. For this purpose, an inventory of the vegetation was carried out in circular pieces of land of 1250 m2, as a sample of the zone of work, based on the chart of occupation of the grounds. We are identified 158 species comprising 90 genera and 47 families. Those species represent more than 90% of the trees from which various parts are used in food, traditional pharmacopeia and the craft industry. We also showed that because of the strong anthropisation of the zone, the bad pedoclimatic conditions and the permanent bush fires, the regeneration and growth of Vitellaria paradoxa, Balanites aegyptiaca, Tamarindus indica and Lannea microcarpa are disturbed.

  8. Background Suppression and Feature Based Spectroscopy Methods for Subpixel Material Identification

    Science.gov (United States)

    2012-08-03

    were computed from five regions of the scene representing gravel, sand, grass, trees, and stressed vegetation . ©2012 The MITRE Corporation...built-up areas using neural networks and subpixel demixing methods on multispectral /hyperspectral data”, Proceedings of the 23st Annual Conference of

  9. A reconnaissance survey of the woody flora and vegetation of the Catapú logging concession, Cheringoma District, Mozambique

    Directory of Open Access Journals (Sweden)

    M. Coates Palgrave

    2007-12-01

    Full Text Available A checklist of the trees, shrubs and Hanes of Catapú, Cheringoma District, Mozambique, is presented. Floristically the study area falls within the Swahilian/Maputaland Regional Transition Zone. In total, 238 woody species and infraspecific taxa have been recorded, representing 59 families and 167 genera. Most species (64% occur both to the north and south of the study area. 26% have their core distribution in the Swahilian Regional Centre of Endemism, 4% have a more southerly distribution. 14 are endemic to the Swahilian/Maputaland Regional Transition Zone and two near-endemic, extending into the Zambezian Regional Centre of Endemism only along the Zambezi River Valley as far west as Kariba. The checklist includes the Sena names for 191 species, 77 of which are recorded for the first time. Comparisons of the Catapú checklist are made with other checklists.

  10. Belowground eco-restoration of a suburban waste-storage landscape: Earthworm dynamics in grassland and in a succession of woody vegetation covers.

    Science.gov (United States)

    Morales, Pamela K; Yunusa, Isa A M; Lugg, Glenys; Li, Zheng; Gribben, Paul; Eamus, Derek

    2013-12-01

    Restoration of belowground ecology is seldom a priority in designing revegetation strategies for disturbed landscapes. We determined earthworm abundance and diversity in a 16-year old grass sward (grassland), a 6-year old (Plantation-04) and a 4-year old (Plantation-06) plantation, both of mixed woody species, on a reclaimed waste disposal site, and in nearby remnant woodland, in suburban Sydney, Australia. While no catches were made in autumn, more earthworms were found in spring (21 ± 8.6 m-2) than in winter (10.2 ± 5.9 m-2) or summer (14.4 ± 5.5 m-2). Earthworm abundance in spring was in the order grassland ≈ Plantation-04 (35.2 m-2) > woodland (12.8 m-2) > Plantation-06 (0.8 m-2). None of the revegetated covers had restored earthworm diversity to levels found in the woodland. Exotic species, mostly Microscolex dubius, dominated in the four vegetation covers at any time; the only two native species (Heteroporodrilus sp. and Megascoleceides sp.) found were in the woodland. We also assessed how quality of the evolving soils from the three revegetated covers, compared with that from the woodland, impacted viability of common exotic earthworm species. Both weight gain and cocoon production by the exotic earthworms were higher in the soil from Plantation-04 than in soils from the other vegetation covers, including the woodland; the two variables were positively correlated with the pH and mineral nutrient content (as indicated by electrical conductivity that was in turn correlated with clay content) of the soil. Age of vegetation rather than its composition explained differences in the level of earthworm recovery observed.

  11. SHARE 2012: subpixel detection and unmixing experiments

    Science.gov (United States)

    Kerekes, John P.; Ludgate, Kyle; Giannandrea, AnneMarie; Raqueno, Nina G.; Goldberg, Daniel S.

    2013-05-01

    The quantitative evaluation of algorithms applied to remotely sensed hyperspectral imagery require data sets with known ground truth. A recent data collection known as SHARE 2012, conducted by scientists in the Digital Imaging and Remote Sensing Laboratory at the Rochester Institute of Technology together with several outside collaborators, acquired hyperspectral data with this goal in mind. Several experiments were designed, deployed, and ground truth collected to support algorithm evaluation. In this paper, we describe two experiments that addressed the particular needs for the evaluation of subpixel detection and unmixing algorithms. The subpixel detection experiment involved the deployment of dozens of nearly identical subpixel targets in a random spatial array. The subpixel targets were pieces of wood painted either green or yellow. They were sized to occupy about 5% to 20% of the 1 m pixels. The unmixing experiment used novel targets with prescribed fractions of different materials based on a geometric arrangement of subpixel patterns. These targets were made up of different fabrics with various colors. Whole pixel swatches of the same materials were also deployed in the scene to provide in-scene endmembers. Alternatively, researchers can use the unmixing targets alone to derive endmembers from the mixed pixels. Field reflectance spectra were collected for all targets and adjacent background areas. While efforts are just now underway to evaluate the detection performance using the subpixel targets, initial results for the unmixing targets have demonstrated retrieved fractions that are close approximations to the geometric fractions. These data, together with the ground truth, are planned to be made available to the remote sensing research community for evaluation and development of detection and unmixing algorithms.

  12. PEMANFAATAN DAUN TANAMAN BERKAYU SEBAGAI PUPUK ORGANIK TANAMAN SAYURAN DAN JAGUNG - (UTILIZATION OF WOODY PLANT LEAVES AS ORGANIC FERTILIZER FOR VEGETABLES AND CORN

    Directory of Open Access Journals (Sweden)

    Dody Priadi

    2017-12-01

    Full Text Available This study aimed to use woody plant leaves as organic fertilizer (compost and their effects on vegetables and corn. The compost was made from leaves of Samanea saman, Swietenia macrophylla, Nephelium lappaceum and cow dung (1:3, 2:2 and 3:1 using OrgaDec (0.5% w/w, Decomic (0.1% v/w and Dectro (0.1 v/w as bioactivator. The result showed that compost from Samanea saman leaves and cow dung (1:3 using Decomic (0.1% v/w met the organic fertilizer standard. The compost was applied to Ipomoea reptans, Capsicum annuum and Zea mays on a media from compost and latosol soil (1:3, 2:2 and 3:1 using Completely Randomized Design (CRD with 3 replications. The analyzed data using ANOVA showed no significant difference in the growth parameter of tested plants. The best media for Ipomoea reptans was the mixture of compost and latosol soil (3:1 meanwhile for Zea mays and Capsicum annuum were 1:3 and 2:2, respectively.Keywords: compost, compost application, organic fertilizer, woody plant leavesABSTRAKPenelitian ini bertujuan untuk memanfaatkan daun tumbuhan berkayu menjadi pupuk organik (kompos serta pengaruhnya terhadap tanaman sayuran dan jagung. Kompos dibuat dari daun kihujan (Samanea saman, daun mahoni (Swietenia macrophylla daun rambutan (Nephelium lappaceum dan kotoran sapi (1:3, 2:2 dan 3:1 dengan penambahan bioaktivator OrgaDec (0,5% w/w, Decomic (0,1% v/w dan Dectro (0,1 v/w. Hasil analisis kimia menunjukkan bahwa kompos yang dibuat dari daun kihujan dan kotoran sapi (1:3 yang menggunakan bioaktivator Decomic (0,1% v/w adalah perlakuan yang paling sesuai dengan baku mutu pupuk organik berdasarkan Permentan No.70/Permentan/SR.140/10/2011. Kompos hasil penelitian diujicobakan kepada tanaman kangkung darat (Ipomoea reptans, cabe keriting (Capsicum annuum dan jagung manis (Zea mays pada media campuran kompos dan tanah latosol (1:3, 2:2 dan 3:1 menggunakan Rancangan Acak Lengkap (RAL dengan 3 ulangan sedangkan data yang diperoleh diolah dengan ANOVA

  13. Comparison of three sub-pixel computation approaches

    Science.gov (United States)

    Zhao, An; Zheng, Lin; Jiang, Meixin

    2005-10-01

    Sub-pixel classification is a tough issue in remote sensing field. Although many kinds of software or its Module can be used to address this problem, their rationale, algorithms and methodologies are different, resulting in different use of different method for different purpose. This makes many users feel confused when they want to detect mixed feature content within a pixel and to use sub-pixel approach for practical application. It is necessary to make an in-depth comparison study for different sub-pixel methods in order for RS&GIS users to choose proper sub-pixel methods for their specific applications. After reviewing the basic theories and methods in dealing with sub-pixels, this paper made an introductory analysis to their principles, algorithms, parameters and computing process of three sub-pixel calculation methods, or Linear Unmixing in platform ILWIS3.0, Erdas8.5's Sub-pixel Classifier, eCognition3.0's Nearest Neighbor. A case study of three sub-pixel methods was then made of flood monitoring in Poyang Lake region of P.R.China with image data of band-1 and band-2 of NOAA AVHRR image. Finally, a theoretic, technological and practical comparison study was made of these three sub-pixel methods in aspects of the basic principles, the parameters to be set, the suitable application fields and their respective use limitation. Opinions and comments were presented in the end on the use of the sub-pixel calculation results of these three methods in a hope to provide some reference to future sub-pixel application study for the researchers in interest.

  14. Estimation of Subpixel Motion Using Bispectrum

    Directory of Open Access Journals (Sweden)

    El Mehdi Ismaili Aalaoui

    2008-01-01

    Full Text Available Motion estimation techniques are widely used in today's video processing systems. The frequently used techniques are frequency-domain motion estimation methods, most notably phase correlation (PC. If the image frames are corrupted by Gaussian noises, then cross-correlation and related techniques do not work well. In this paper, however, we have studied this topic from a viewpoint different from the above. Our scheme is based on the bispectrum method for sub-pixel motion estimation of noisy image sequences. Experimental results show that our proposed method performs significantly better than PC technique.

  15. Woody structure facilitates invasion of woody plants by providing perches for birds.

    Science.gov (United States)

    Prather, Chelse M; Huynh, Andrew; Pennings, Steven C

    2017-10-01

    Woody encroachment threatens prairie ecosystems globally, and thus understanding the mechanisms that facilitate woody encroachment is of critical importance. Coastal tallgrass prairies along the Gulf Coast of the US are currently threatened by the spread of several species of woody plants. We studied a coastal tallgrass prairie in Texas, USA, to determine if existing woody structure increased the supply of seeds from woody plants via dispersal by birds. Specifically, we determined if (i) more seedlings of an invasive tree ( Tridacia sebifera ) are present surrounding a native woody plant ( Myrica cerifera ); (ii) wooden perches increase the quantity of seeds dispersed to a grassland; and (iii) perches alter the composition of the seed rain seasonally in prairie habitats with differing amounts of native and invasive woody vegetation, both underneath and away from artificial wooden perches. More T. sebifera seedlings were found within M. cerifera patches than in graminoid-dominated areas. Although perches did not affect the total number of seeds, perches changed the composition of seed rain to be less dominated by grasses and forbs. Specifically, 20-30 times as many seeds of two invasive species of woody plants were found underneath perches independent of background vegetation, especially during months when seed rain was highest. These results suggest that existing woody structure in a grassland can promote further woody encroachment by enhancing seed dispersal by birds. This finding argues for management to reduce woody plant abundance before exotic plants set seeds and argues against the use of artificial perches as a restoration technique in grasslands threatened by woody species.

  16. Assessment of the mapping of fractional woody cover in southern African savannas using multi-temporal and polarimetric ALOS PALSAR L-band images

    CSIR Research Space (South Africa)

    Urbazaev, M

    2015-09-01

    Full Text Available Woody vegetation cover affects several ecosystem processes including carbon and water cycling, energy fluxes, and fire regimes. In order to understand the dynamics of savanna ecosystems, information on the spatial distribution of woody vegetation...

  17. Rough wave-like heaped overburden promotes establishment of woody vegetation while leveling promotes grasses during unassisted post mining site development.

    Science.gov (United States)

    Frouz, Jan; Mudrák, Ondřej; Reitschmiedová, Erika; Walmsley, Alena; Vachová, Pavla; Šimáčková, Hana; Albrechtová, Jana; Moradi, Jabbar; Kučera, Jiří

    2018-01-01

    Geodiversity plays an important role in species establishment during spontaneous succession. At post-mining sites in the Czech Republic in 2003, we established plots in which the surface of the heaped overburden was either kept wave-like or leveled. Based on surveys conducted from 2006 to 2015, leveled plots were increasingly dominated by grasses and herbs (and especially by the grass Calamagrostis epigejos) while the wave-like plots were increasingly dominated by the trees Salix caprea and Betula pendula. In 2015, a detailed survey was conducted of the dominant species. Both S. caprea and B. pendula occurred more often in wave-like plots than in leveled plots; this was particularly true for trees taller than 1 m, which were absent in leveled plots. In wave-like plots, leaf and root biomasses of both woody species were higher on the wave slopes than on the wave depressions. Nitrogen content was higher but content stress indicating proline in leaves of S. caprea was lower in wave-like plots than in leveled plots. In wave-like plots, both woody species occurred mainly on wave slopes but C. epigejos occurred mainly in the depressions. We speculate that trees were more abundant in wave-like plots than in leveled plots because the waves trapped tree seeds and snow and because the soil porosity was greater in wave-like than in leveled plots. Grasses may have preferred the leveled plots because soil porosity was lower and clay content was higher in leveled than in wave-like plots. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Effect of non-crop vegetation types on conservation biological control of pests in olive groves

    National Research Council Canada - National Science Library

    Paredes, Daniel; Cayuela, Luis; Gurr, Geoff M; Campos, Mercedes

    2013-01-01

    ...) and the olive moth (Prays oleae). Areas of herbaceous vegetation and areas of woody vegetation near olive crops, and smaller patches of woody vegetation within olive groves, decreased pest abundance in the crop...

  19. Vegetation

    DEFF Research Database (Denmark)

    Epstein, H.E.; Walker, D.A.; Bhatt, U.S.

    2012-01-01

    • Over the past 30 years (1982-2011), the Normalized Difference Vegetation Index (NDVI), an index of green vegetation, has increased 15.5% in the North American Arctic and 8.2% in the Eurasian Arctic. In the more southern regions of Arctic tundra, the estimated aboveground plant biomass has...... in vegetation (including shrub tundra expansion) and thunderstorm activity, each a result of Arctic warming, have created conditions that favor a more active Arctic fire regime....

  20. Three-dimensional woody vegetation structure across different land-use types and land-use intensities in a semi-arid savanna

    CSIR Research Space (South Africa)

    Fisher, J

    2009-07-01

    Full Text Available footprint discrete return LiDAR data (1.12 m point spacing) from the Carnegie Airborne Observatory (CAO) ‘Alpha system’ were used to measure three-dimensional vegetation structure across the different treatments. A volumetric pixel (voxel) approach was used...

  1. Impact of communal land use and conservation on woody vegetation structure in the Lowveld savannas of South Africa – Lidar results

    CSIR Research Space (South Africa)

    Wessels, Konrad J

    2011-04-01

    Full Text Available distributions between communal landscapes with heavy utilization to fully protected public and private reserves in the Lowveld of South Africa. Rangelands and fields in most of the communal sites had more vegetation cover in the 5-7m and >7m classes than most...

  2. Missouri Ozark Forest Ecosystem Project: site history, soils, landforms, woody and herbaceous vegetation, down wood, and inventory methods for the landscape experiment.

    Science.gov (United States)

    Stephen R. Shifley; Brian L., eds. Brookshire

    2000-01-01

    Describes vegetation and physical site conditions at the initiation (1991-1995) of the Missouri Ozark Forest Ecosystem Project (MOFEP) in the southeastern Missouri Ozarks. Provides detailed information on sampling protocols and summarizes initial conditions of the landscape experiment prior to harvest treatments. Summaries are by plot, by ~800-acre...

  3. Subpixel jitter video restoration on board of micro-UAV

    Science.gov (United States)

    Szu, Harold H.; Buss, James R.; Garcia, Joseph P.; Breaux, Nancy A.; Kopriva, Ivica; Karangelen, Nicholas E.; Hsu, M.; Lee, Ting; Willey, Jeff; Shield, Gary; Brown, Steve; Robbins, R.; Hobday, John

    2004-04-01

    We review various image processing algorithms for micro-UAV EO/IR sub-pixel jitter restoration. Since the micro-UAV, Silver Fox, cannot afford isolation coupling mounting from the turbulent aerodynamics of the airframe, we explore smart real-time software to mitigate the sub-pixel jitter effect. We define jitter to be sub-pixel or small-amplitude vibrations up to one pixel, as opposed to motion blur over several pixels for which there already exists real time correction algorithms used on other platforms. We divide the set of jitter correction algorithms into several categories: They are real time, pseudo-real time, or non-real-time, but they are all standalone, i.e. without relying on a library storage or flight data basis on-board the UAV. The top of the list is demonstrated and reported here using real-world data and a truly unsupervised, real-time algorithm.

  4. Notas sobre a composição arbóreo-arbustiva de uma fisionomia das savanas de Roraima, Amazônia Brasileira Notes on the woody composition of a vegetation physionomy of the Roraima's savannas, Brazilian Amazonia

    Directory of Open Access Journals (Sweden)

    Reinaldo Imbrozio Barbosa

    2005-06-01

    Full Text Available Foi realizado um inventário florístico das espécies arbóreo-arbustivas presentes em uma das unidades de vegetação que compõem a paisagem de savanas do Estado de Roraima, extremo norte da Amazônia brasileira. Esta unidade é caracterizada por ser densamente colonizada por ninhos do cupim Cornitermes ovatus Emerson. Foram observadas 29 espécies (15 famílias botânicas em três localidades utilizadas para a amostragem. O total de espécies, por localidade, variou de 12 a 20. As espécies mais abundantes foram Byrsonima verbascifolia (L. DC. e Mimosa microcephala Humb. & Bonpl. ex Willd. (subarbustivas, Byrsonima cf. intermedia A. Juss. e Randia formosa (Jack. K. Schum. (arbustivas e, Byrsonima crassifolia (L. H.B.K. e Curatella americana L. (arbóreas. Oito espécies são comuns às três localidades. A diversidade medida pelo Índice de Shannon (H' foi baixa para todos os locais amostrados (A floristic inventory of woody species was carried out in one of the vegetation units that compose the savannas landscape of the Roraima State, northernmost of Brazilian Amazonia. This unit is characterized by dense colonization of nests of termites Cornitermes ovatus Emerson. Twenty nine woody species were observed (15 botany families in three localities used for sampling. The total of species varied from 12 to 20 by locality. The most abundant species were Byrsonima verbascifolia (L. DC. and Mimosa microcephala Humb. & Bonpl. ex Willd. (dwarf shrubs, Byrsonima cf. intermedia A. Juss. and Randia formosa (Jack. K. Schum. (shrubby and, Byrsonima crassifolia (L. H.B.K. and Curatella americana L. (arboreal. Eight species are common to all localities. Diversity measured by the Index of Shannon (H' was low for all the areas sampled (<0.90 indicating high specimens concentration in few species. The Index of Sørensen indicated similarities (± 0.60 among studied areas, suggesting a group of landscapes with common plant diversity, representing a same

  5. Vegetation composition and structure influences bird species ...

    African Journals Online (AJOL)

    Vegetation composition and structure influences bird species community assemblages in the highland agricultural landscape of Nyandarua, Kenya. ... Bird species diversity increased with increasing density of woody plant species and vegetation structural heterogeneity. Two gradients of increasing vegetation structural ...

  6. Frost resistance in alpine woody plants.

    Science.gov (United States)

    Neuner, Gilbert

    2014-01-01

    This report provides a brief review of key findings related to frost resistance in alpine woody plant species, summarizes data on their frost resistance, highlights the importance of freeze avoidance mechanisms, and indicates areas of future research. Freezing temperatures are possible throughout the whole growing period in the alpine life zone. Frost severity, comprised of both intensity and duration, becomes greater with increasing elevation and, there is also a greater probability, that small statured woody plants, may be insulated by snow cover. Several frost survival mechanisms have evolved in woody alpine plants in response to these environmental conditions. Examples of tolerance to extracellular freezing and freeze dehydration, life cycles that allow species to escape frost, and freeze avoidance mechanisms can all be found. Despite their specific adaption to the alpine environment, frost damage can occur in spring, while all alpine woody plants have a low risk of frost damage in winter. Experimental evidence indicates that premature deacclimation in Pinus cembra in the spring, and a limited ability of many species of alpine woody shrubs to rapidly reacclimate when they lose snow cover, resulting in reduced levels of frost resistance in the spring, may be particularly critical under the projected changes in climate. In this review, frost resistance and specific frost survival mechanisms of different organs (leaves, stems, vegetative and reproductive over-wintering buds, flowers, and fruits) and tissues are compared. The seasonal dynamics of frost resistance of leaves of trees, as opposed to woody shrubs, is also discussed. The ability of some tissues and organs to avoid freezing by supercooling, as visualized by high resolution infrared thermography, are also provided. Collectively, the report provides a review of the complex and diverse ways that woody plants survive in the frost dominated environment of the alpine life zone.

  7. Edaphic, structural and physiological contrasts across Amazon Basin forest–savanna ecotones suggest a role for potassium as a key modulator of tropical woody vegetation structure and function

    Directory of Open Access Journals (Sweden)

    J. Lloyd

    2015-11-01

    C / N ratios than nearby forest plots. These soil differences were also reflected in canopy averaged leaf traits with savanna trees typically having higher leaf mass per unit area but lower mass-based nitrogen (Nm and potassium (Km. Both Nm and Km also increased with declining mean annual precipitation (PA, but most area-based leaf traits such as leaf photosynthetic capacity showed no systematic variation with PA or vegetation type. Despite this invariance, when taken in conjunction with other measures such as mean canopy height, area-based soil exchangeable potassium content, [K]sa , proved to be an excellent predictor of several photosynthetic properties (including 13C isotope discrimination. Moreover, when considered in a multivariate context with PA and soil plant available water storage capacity (θP as covariates, [K]sa also proved to be an excellent predictor of stand-level canopy area, providing drastically improved fits as compared to models considering just PA and/or θP. Neither calcium, nor magnesium, nor soil pH could substitute for potassium when tested as alternative model predictors (ΔAIC > 10. Nor for any model could simple soil texture metrics such as sand or clay content substitute for either [K]sa or θP. Taken in conjunction with recent work in Africa and the forests of the Amazon Basin, this suggests – in combination with some newly conceptualised interacting effects of PA and θP also presented here – a critical role for potassium as a modulator of tropical vegetation structure and function.

  8. Woody Allen kimpus arhitektuuriga

    Index Scriptorium Estoniae

    2000-01-01

    Woody Allen protesteerib oma uue lühifilmiga kavatsuse vastu ehitada 16-korruseline ärihoone tema New Yorgi kodu lähedale. W. Allen hindab New Yorgi ajaloolisi rajoone, mida näitab ka oma filmides

  9. Spatial variability of extreme rainfall at radar subpixel scale

    Science.gov (United States)

    Peleg, Nadav; Marra, Francesco; Fatichi, Simone; Paschalis, Athanasios; Molnar, Peter; Burlando, Paolo

    2018-01-01

    Extreme rainfall is quantified in engineering practice using Intensity-Duration-Frequency curves (IDF) that are traditionally derived from rain-gauges and more recently also from remote sensing instruments, such as weather radars. These instruments measure rainfall at different spatial scales: rain-gauge samples rainfall at the point scale while weather radar averages precipitation on a relatively large area, generally around 1 km2. As such, a radar derived IDF curve is representative of the mean areal rainfall over a given radar pixel and neglects the within-pixel rainfall variability. In this study, we quantify subpixel variability of extreme rainfall by using a novel space-time rainfall generator (STREAP model) that downscales in space the rainfall within a given radar pixel. The study was conducted using a unique radar data record (23 years) and a very dense rain-gauge network in the Eastern Mediterranean area (northern Israel). Radar-IDF curves, together with an ensemble of point-based IDF curves representing the radar subpixel extreme rainfall variability, were developed fitting Generalized Extreme Value (GEV) distributions to annual rainfall maxima. It was found that the mean areal extreme rainfall derived from the radar underestimate most of the extreme values computed for point locations within the radar pixel (on average, ∼70%). The subpixel variability of rainfall extreme was found to increase with longer return periods and shorter durations (e.g. from a maximum variability of 10% for a return period of 2 years and a duration of 4 h to 30% for 50 years return period and 20 min duration). For the longer return periods, a considerable enhancement of extreme rainfall variability was found when stochastic (natural) climate variability was taken into account. Bounding the range of the subpixel extreme rainfall derived from radar-IDF can be of major importance for different applications that require very local estimates of rainfall extremes.

  10. Assessing the effects of woody plant traits on understory herbaceous cover in a semiarid rangeland.

    Science.gov (United States)

    Belay, Tamrat A; Moe, Stein R

    2015-07-01

    The ecological impact of woody plant encroachment in rangeland ecosystems has traditionally been evaluated based on correlation studies between densities of dissimilar woody plants and various ecosystem properties. However, ecosystem properties respond differently to woody plant encroachment because of variations in adaptation of co-occurring woody plants. The objective of this study is to predict the impact of woody plant encroachment on understory herbaceous cover based on analysis of key traits of woody plants. We conducted a vegetation survey in 4 savanna sites in southwestern Ethiopia and compared 9 different key traits of 19 co-occurring woody plants with understory herbaceous cover. Our results show that low understory herbaceous cover is associated with evergreen leaf phenology, shrubby growth form, smaller relative crown-base height and larger relative crown diameter. However, the N2-fixing ability and density of woody plants did not influence the understory herbaceous cover. This shows that traits of individual woody plants can predict the impact of woody plant encroachment on understory herbaceous cover better than density does. The finding improves our ability to accurately predict the impact of woody plant encroachment on various ecosystem properties in highly diverse savanna systems. This plant trait-based approach could be also used as an important management exercise to assess and predict the impact of encroaching woody species in several rangeland ecosystems.

  11. Ordinal Regression Based Subpixel Shift Estimation for Video Super-Resolution

    Directory of Open Access Journals (Sweden)

    Petrovic Nemanja

    2007-01-01

    Full Text Available We present a supervised learning-based approach for subpixel motion estimation which is then used to perform video super-resolution. The novelty of this work is the formulation of the problem of subpixel motion estimation in a ranking framework. The ranking formulation is a variant of classification and regression formulation, in which the ordering present in class labels namely, the shift between patches is explicitly taken into account. Finally, we demonstrate the applicability of our approach on superresolving synthetically generated images with global subpixel shifts and enhancing real video frames by accounting for both local integer and subpixel shifts.

  12. Mapping the Spatial Distribution of Winter Crops at Sub-Pixel Level Using AVHRR NDVI Time Series and Neural Nets

    Directory of Open Access Journals (Sweden)

    Felix Rembold

    2013-03-01

    Full Text Available For large areas, it is difficult to assess the spatial distribution and inter-annual variation of crop acreages through field surveys. Such information, however, is of great value for governments, land managers, planning authorities, commodity traders and environmental scientists. Time series of coarse resolution imagery offer the advantage of global coverage at low costs, and are therefore suitable for large-scale crop type mapping. Due to their coarse spatial resolution, however, the problem of mixed pixels has to be addressed. Traditional hard classification approaches cannot be applied because of sub-pixel heterogeneity. We evaluate neural networks as a modeling tool for sub-pixel crop acreage estimation. The proposed methodology is based on the assumption that different cover type proportions within coarse pixels prompt changes in time profiles of remotely sensed vegetation indices like the Normalized Difference Vegetation Index (NDVI. Neural networks can learn the relation between temporal NDVI signatures and the sought crop acreage information. This learning step permits a non-linear unmixing of the temporal information provided by coarse resolution satellite sensors. For assessing the feasibility and accuracy of the approach, a study region in central Italy (Tuscany was selected. The task consisted of mapping the spatial distribution of winter crops abundances within 1 km AVHRR pixels between 1988 and 2001. Reference crop acreage information for network training and validation was derived from high resolution Thematic Mapper/Enhanced Thematic Mapper (TM/ETM+ images and official agricultural statistics. Encouraging results were obtained demonstrating the potential of the proposed approach. For example, the spatial distribution of winter crop acreage at sub-pixel level was mapped with a cross-validated coefficient of determination of 0.8 with respect to the reference information from high resolution imagery. For the eight years for which

  13. William L Finley - Woody Vegetation Removal

    Data.gov (United States)

    Department of the Interior — The initial project was targeted for ‘hidden prairies’ along Muddy Creek. With the loss of the supervisory biologist position, the focus of this project was changed...

  14. 2D Sub-Pixel Disparity Measurement Using QPEC / Medicis

    Directory of Open Access Journals (Sweden)

    M. Cournet

    2016-06-01

    Full Text Available In the frame of its earth observation missions, CNES created a library called QPEC, and one of its launcher called Medicis. QPEC / Medicis is a sub-pixel two-dimensional stereo matching algorithm that works on an image pair. This tool is a block matching algorithm, which means that it is based on a local method. Moreover it does not regularize the results found. It proposes several matching costs, such as the Zero mean Normalised Cross-Correlation or statistical measures (the Mutual Information being one of them, and different match validation flags. QPEC / Medicis is able to compute a two-dimensional dense disparity map with a subpixel precision. Hence, it is more versatile than disparity estimation methods found in computer vision literature, which often assume an epipolar geometry. CNES uses Medicis, among other applications, during the in-orbit image quality commissioning of earth observation satellites. For instance the Pléiades-HR 1A & 1B and the Sentinel-2 geometric calibrations are based on this block matching algorithm. Over the years, it has become a common tool in ground segments for in-flight monitoring purposes. For these two kinds of applications, the two-dimensional search and the local sub-pixel measure without regularization can be essential. This tool is also used to generate automatic digital elevation models, for which it was not initially dedicated. This paper deals with the QPEC / Medicis algorithm. It also presents some of its CNES applications (in-orbit commissioning, in flight monitoring or digital elevation model generation. Medicis software is distributed outside the CNES as well. This paper finally describes some of these external applications using Medicis, such as ground displacement measurement, or intra-oral scanner in the dental domain.

  15. Pathogenicity and virulence of the two Dutch VCGs of Verticillium dahliae to woody ornamentals

    NARCIS (Netherlands)

    Goud, J.C.; Termorshuizen, A.J.

    2002-01-01

    Two experiments were performed in two consecutive years to test whether isolates of different vegetative compatibility groups (VCGs) differ in their ability to cause disease in woody ornamentals, to study the host specificity of the isolates and to get an insight into disease development in woody

  16. Effects of herbaceous and woody plant control on longleaf pine growth and understory plant cover

    Science.gov (United States)

    James D. Haywood

    2013-01-01

    To determine if either herbaceous or woody plants are more competitive with longleaf pine (Pinus palustris Mill.) trees, four vegetation management treatments— check, herbaceous plant control (HPC), woody plant control (WPC), and HPC+WPC—were applied in newly established longleaf pine plantings in a randomized complete block design in two studies....

  17. Wild ungulate herbivory suppresses deciduous woody plant establishment following salmonid stream restoration

    Science.gov (United States)

    Joshua P. Averett; Bryan A. Endress; Mary M. Rowland; Bridgett J. Naylor; Michael J. Wisdom

    2017-01-01

    Domestic and wild ungulates can exert strong influences on riparian woody vegetation establishment, yet little is known about how wild ungulate herbivory affects riparian restoration in the absence of cattle. We evaluated elk (Cervus elaphus) and mule deer (Odocoileus hemionus) impacts on the establishment of deciduous woody...

  18. Sub-pixel Area Calculation Methods for Estimating Irrigated Areas

    Directory of Open Access Journals (Sweden)

    Suraj Pandey

    2007-10-01

    Full Text Available The goal of this paper was to develop and demonstrate practical methods forcomputing sub-pixel areas (SPAs from coarse-resolution satellite sensor data. Themethods were tested and verified using: (a global irrigated area map (GIAM at 10-kmresolution based, primarily, on AVHRR data, and (b irrigated area map for India at 500-mbased, primarily, on MODIS data. The sub-pixel irrigated areas (SPIAs from coarse-resolution satellite sensor data were estimated by multiplying the full pixel irrigated areas(FPIAs with irrigated area fractions (IAFs. Three methods were presented for IAFcomputation: (a Google Earth Estimate (IAF-GEE; (b High resolution imagery (IAF-HRI; and (c Sub-pixel de-composition technique (IAF-SPDT. The IAF-GEE involvedthe use of “zoom-in-views” of sub-meter to 4-meter very high resolution imagery (VHRIfrom Google Earth and helped determine total area available for irrigation (TAAI or netirrigated areas that does not consider intensity or seasonality of irrigation. The IAF-HRI isa well known method that uses finer-resolution data to determine SPAs of the coarser-resolution imagery. The IAF-SPDT is a unique and innovative method wherein SPAs aredetermined based on the precise location of every pixel of a class in 2-dimensionalbrightness-greenness-wetness (BGW feature-space plot of red band versus near-infraredband spectral reflectivity. The SPIAs computed using IAF-SPDT for the GIAM was within2 % of the SPIA computed using well known IAF-HRI. Further the fractions from the 2 methods were significantly correlated. The IAF-HRI and IAF-SPDT help to determine annualized or gross irrigated areas (AIA that does consider intensity or seasonality (e.g., sum of areas from season 1, season 2, and continuous year-round crops. The national census based irrigated areas for the top 40 irrigated nations (which covers about 90% of global irrigation was significantly better related (and had lesser uncertainties and errors when

  19. The subpixel resolution of optical-flow-based modal analysis

    Science.gov (United States)

    Javh, Jaka; Slavič, Janko; Boltežar, Miha

    2017-05-01

    This research looks at the possibilities for full-field, non-contact, displacement measurements based on high-speed video analyses. A simplified gradient-based optical flow method, optimised for subpixel harmonic displacements, is used to predict the resolution potential. The simplification assumes an image-gradient linearity, producing a linear relation between the light intensity and the displacement in the direction of the intensity gradient. The simplicity of the method enables each pixel or small subset to be viewed as a sensor. The resolution potential and the effect of noise are explored theoretically and tested in a synthetic experiment, which is followed by a real experiment. The identified displacement can be smaller than a thousandth of a pixel and subpixel displacements are recognisable, even with a high image noise. The resolution and the signal-to-noise ratio are influenced by the dynamic range of the camera, the subset size and the sampling length. Real-world experiments were performed to validate and demonstrate the method using a monochrome high-speed camera. One-dimensional mode shapes of a steel beam are recognisable even at the maximum displacement amplitude of 0.0008 pixel (equal to 0.2 μm) and multiple out-of-plane mode shapes are recognisable from the high-speed video of a vibrating cymbal.

  20. Gasification of Woody Biomass.

    Science.gov (United States)

    Dai, Jianjun; Saayman, Jean; Grace, John R; Ellis, Naoko

    2015-01-01

    Interest in biomass to produce heat, power, liquid fuels, hydrogen, and value-added chemicals with reduced greenhouse gas emissions is increasing worldwide. Gasification is becoming a promising technology for biomass utilization with a positive environmental impact. This review focuses specifically on woody biomass gasification and recent advances in the field. The physical properties, chemical structure, and composition of biomass greatly affect gasification performance, pretreatment, and handling. Primary and secondary catalysts are of key importance to improve the conversion and cracking of tars, and lime-enhanced gasification advantageously combines CO2 capture with gasification. These topics are covered here, including the reaction mechanisms and biomass characterization. Experimental research and industrial experience are investigated to elucidate concepts, processes, and characteristics of woody biomass gasification and to identify challenges.

  1. Mistletoe infection of woody plant species at Bahir Dar University ...

    African Journals Online (AJOL)

    Study of woody plants composition and invasion by mistletoes was conducted in Bahir Dar University main campus vegetation. A total of 28009 individual trees were checked for mistletoes infection and 764 trees were found parasitized. Three species of mistletoes were identified. Erianthemum dregi was more frequent and ...

  2. Measuring biomass and carbon stock in resprouting woody plants.

    Science.gov (United States)

    Matula, Radim; Damborská, Lenka; Nečasová, Monika; Geršl, Milan; Šrámek, Martin

    2015-01-01

    Resprouting multi-stemmed woody plants form an important component of the woody vegetation in many ecosystems, but a clear methodology for reliable measurement of their size and quick, non-destructive estimation of their woody biomass and carbon stock is lacking. Our goal was to find a minimum number of sprouts, i.e., the most easily obtainable, and sprout parameters that should be measured for accurate sprout biomass and carbon stock estimates. Using data for 5 common temperate woody species, we modelled carbon stock and sprout biomass as a function of an increasing number of sprouts in an interaction with different sprout parameters. The mean basal diameter of only two to five of the thickest sprouts and the basal diameter and DBH of the thickest sprouts per stump proved to be accurate estimators for the total sprout biomass of the individual resprouters and the populations of resprouters, respectively. Carbon stock estimates were strongly correlated with biomass estimates, but relative carbon content varied among species. Our study demonstrated that the size of the resprouters can be easily measured, and their biomass and carbon stock estimated; therefore, resprouters can be simply incorporated into studies of woody vegetation.

  3. Measuring Biomass and Carbon Stock in Resprouting Woody Plants

    Science.gov (United States)

    Matula, Radim; Damborská, Lenka; Nečasová, Monika; Geršl, Milan; Šrámek, Martin

    2015-01-01

    Resprouting multi-stemmed woody plants form an important component of the woody vegetation in many ecosystems, but a clear methodology for reliable measurement of their size and quick, non-destructive estimation of their woody biomass and carbon stock is lacking. Our goal was to find a minimum number of sprouts, i.e., the most easily obtainable, and sprout parameters that should be measured for accurate sprout biomass and carbon stock estimates. Using data for 5 common temperate woody species, we modelled carbon stock and sprout biomass as a function of an increasing number of sprouts in an interaction with different sprout parameters. The mean basal diameter of only two to five of the thickest sprouts and the basal diameter and DBH of the thickest sprouts per stump proved to be accurate estimators for the total sprout biomass of the individual resprouters and the populations of resprouters, respectively. Carbon stock estimates were strongly correlated with biomass estimates, but relative carbon content varied among species. Our study demonstrated that the size of the resprouters can be easily measured, and their biomass and carbon stock estimated; therefore, resprouters can be simply incorporated into studies of woody vegetation. PMID:25719601

  4. Characterizing Subpixel Spatial Resolution of a Hybrid CMOS Detector

    Science.gov (United States)

    Bray, Evan; Burrows, Dave; Chattopadhyay, Tanmoy; Falcone, Abraham; Hull, Samuel; Kern, Matthew; McQuaide, Maria; Wages, Mitchell

    2018-01-01

    The detection of X-rays is a unique process relative to other wavelengths, and allows for some novel features that increase the scientific yield of a single observation. Unlike lower photon energies, X-rays liberate a large number of electrons from the silicon absorber array of the detector. This number is usually on the order of several hundred to a thousand for moderate-energy X-rays. These electrons tend to diffuse outward into what is referred to as the charge cloud. This cloud can then be picked up by several pixels, forming a specific pattern based on the exact incident location. By conducting the first ever “mesh experiment" on a hybrid CMOS detector (HCD), we have experimentally determined the charge cloud shape and used it to characterize responsivity of the detector with subpixel spatial resolution.

  5. Woody plants and woody plant management: ecology, safety, environmental impact

    Science.gov (United States)

    James H. Miller

    2001-01-01

    Wise and effective woody plant management is an increasing necessity for many land uses and conservation practices, especially on forests and rangelands where native or exotic plants are affecting productivity, access, or critical habitat. Tools and approaches for managing woody plants have been under concerted development for the past 50 years, integrating mechanical...

  6. Woody biomass logistics [Chapter 14

    Science.gov (United States)

    Robert Keefe; Nathaniel Anderson; John Hogland; Ken Muhlenfeld

    2014-01-01

    The economics of using woody biomass as a fuel or feedstock for bioenergy applications is often driven by logistical considerations. Depending on the source of the woody biomass, the acquisition cost of the material is often quite low, sometimes near zero. However, the cost of harvesting, collection, processing, storage, and transportation from the harvest site to end...

  7. Evaluating Fourier Cross-Correlation Sub-Pixel Registration in Landsat Images

    National Research Council Canada - National Science Library

    Jaime Almonacid-Caballer; Josep E Pardo-Pascual; Luis A Ruiz

    2017-01-01

    .... In this paper, we simulate Landsat scenes to evaluate, by means of an exhaustive number of tests, a subpixel registration process based on phase correlation and the upsampling of the Fourier transform...

  8. Sub-pixel analysis to enhance the accuracy of evapotranspiration determined using MODIS images

    National Research Council Canada - National Science Library

    Abdalhaleem A Hassaballa; Abdul-Nasir Matori; Khalid A Al-Gaadi; Elkamil H Tola; Rangaswamy Madugundu

    2017-01-01

    ...) were recorded at the time of satellite overpass. In order to enhance the accuracy of the generated ET maps, MODIS images were subjected to sub-pixel analysis by assigning weights for different land surface cover...

  9. Remote sensing research for spatial assessment of woody structure in African savannahs & woodlands –past, on-going, and future work by the CSIR

    CSIR Research Space (South Africa)

    Mathieu, Renaud SA

    2011-04-01

    Full Text Available Appropriate techniques are needed to monitor woody vegetation cover, biomass and carbon stocks. Light Detection and Ranging (LiDAR) & Synthetic Aperture Radar (SAR) interact with vegetation morphology and structure. The aim of this study...

  10. Autonomous Sub-Pixel Satellite Track Endpoint Determination for Space Based Images

    Energy Technology Data Exchange (ETDEWEB)

    Simms, L M

    2011-03-07

    An algorithm for determining satellite track endpoints with sub-pixel resolution in spaced-based images is presented. The algorithm allows for significant curvature in the imaged track due to rotation of the spacecraft capturing the image. The motivation behind the subpixel endpoint determination is first presented, followed by a description of the methodology used. Results from running the algorithm on real ground-based and simulated spaced-based images are shown to highlight its effectiveness.

  11. Effects of herbaceous and woody plant control on Pinus palustris growth and foliar nutrients through six growing seasons

    Science.gov (United States)

    James D. Haywood

    2005-01-01

    To determine if either herbaceous or woody plants are more competitive with longleaf pine (Pinuspalustris P. Mill.) seedlings, two vegetation management treatments-herbaceous plant control (HPC, No or Yes) and woody plant control (WPC, No or Yes) were applied in newly established longleaf pine plantings in a randomized complete block 2 x 2 factorial...

  12. Backwater development by woody debris

    Science.gov (United States)

    Geertsema, Tjitske; Torfs, Paul; Teuling, Ryan; Hoitink, Ton

    2017-04-01

    Placement of woody debris is a common method for increasing ecological values in river and stream restoration, and is thus widely used in natural environments. Water managers, however, are afraid to introduce wood in channels draining agricultural and urban areas. Upstream, it may create backwater, depending on hydrodynamic characteristics including the obstruction ratio, the Froude number and the surface level gradient. Patches of wood may trigger or counter morphological activity, both laterally, through bank erosion and protection, and vertically, with pool and riffle formation. Also, a permeable construction composed of wood will weather over time. Both morphodynamic activity and weathering cause backwater effects to change in time. The purpose of this study is to quantify the time development of backwater effects caused by woody debris. Hourly water levels gauged upstream and downstream of patches and discharge are collected for five streams in the Netherlands. The water level drop over the woody debris patch relates to discharge in the streams. This relation is characterized by an increasing water level difference for an increasing discharge, up to a maximum. If the discharge increases beyond this level, the water level difference reduces to the value that may represent the situation without woody debris. This reduction depends primarily on the obstruction ratio of the woody debris in the channel cross-section. Morphologic adjustments in the stream and reorientation of the woody material reduce the water level drop over the patches in time. Our results demonstrate that backwater effects can be reduced by optimizing the location where woody debris is placed and manipulating the obstruction ratio. Current efforts are focussed on representing woody debris in a one-dimensional numerical model, aiming to obtain a generic tool to achieve a stream design with woody debris that minimizes backwater.

  13. Relationship between woody plant colonization and Typha L. encroachment in stormwater detention basins.

    Science.gov (United States)

    Plumb, Priscilla Bocskor; Day, Susan D; Wynn-Thompson, Theresa M; Seiler, John R

    2013-10-01

    We studied stormwater detention basins where woody vegetation removal was suspended for 2 years in Virginia, USA to determine if woody vegetation can control Typha populations and how early woody plant succession interacts with Typha, other herbaceous vegetation, and site factors. Distribution and composition of woody vegetation, Typha and non-Typha herbaceous vegetation biomass, and site factors were assessed at 100 plots in four basins ranging in age from 7 to 17 years. A greenhouse study examined the interaction of shade and soil moisture on Typha biomass and persistence. Principal component analysis identified an environmental gradient associated with greater water table depths and decreased elevation that favored Typha but negatively influenced woody vegetation. Elevation was correlated with litter layer distribution, suggesting that initial topography influences subsequent environmental characteristics and thus plant communities. Soil organic matter at 0-10 cm ranged from 5.4 to 12.7%. Woody plants present were native species with the exception of Ailanthus altissima and Pyrus calleryana. In the greenhouse, shade and reduced soil moisture decreased Typha biomass and rhizome length. The shade effect was strongest in flooded plants and the soil moisture effect was strongest for plants in full sun. Typha in dry soil and heavy shade had 95% less total biomass and 83% smaller rhizomes than Typha in flooded soil and full sun, but even moderate soil moisture reductions decreased above- and below-ground biomass by 63 and 56%, respectively. Suspending maintenance allows restoration of woody vegetation dominated by native species and may suppress Typha invasion.

  14. Evaluating ecohydrological theories of woody root distribution in the Kalahari.

    Directory of Open Access Journals (Sweden)

    Abinash Bhattachan

    Full Text Available The contribution of savannas to global carbon storage is poorly understood, in part due to lack of knowledge of the amount of belowground biomass. In these ecosystems, the coexistence of woody and herbaceous life forms is often explained on the basis of belowground interactions among roots. However, the distribution of root biomass in savannas has seldom been investigated, and the dependence of root biomass on rainfall regime remains unclear, particularly for woody plants. Here we investigate patterns of belowground woody biomass along a rainfall gradient in the Kalahari of southern Africa, a region with consistent sandy soils. We test the hypotheses that (1 the root depth increases with mean annual precipitation (root optimality and plant hydrotropism hypothesis, and (2 the root-to-shoot ratio increases with decreasing mean annual rainfall (functional equilibrium hypothesis. Both hypotheses have been previously assessed for herbaceous vegetation using global root data sets. Our data do not support these hypotheses for the case of woody plants in savannas. We find that in the Kalahari, the root profiles of woody plants do not become deeper with increasing mean annual precipitation, whereas the root-to-shoot ratios decrease along a gradient of increasing aridity.

  15. Non-Linear Dynamics Approach to Assessing Woody-Encroachment in Grasslands

    Science.gov (United States)

    Brunsell, N. A.; Nippert, J. B.; Van Vleck, E.

    2015-12-01

    Woody species are encroaching on grasslands globally. Here, we investigate the spatial and temporal dynamics of this encroachment in relation to climate and fire regimes in the central U.S. A low-dimensional model is used to assess stability of species composition. Sixe years of eddy covariance data at a paired grassland and woody encroachment site at the Konza Prairie LTER site are used to verify carbon and water dynamics. Historical aerial photography and remote sensing data are used to quantify the spatial diffusion of woody tree fraction into grasslands. Non-linear dynamics approaches are used to quantify the stability of vegetation and the presence of tipping points in relation to woody fraction, fire frequency and precipitation and temperature variability. Understanding the roles of multiple confounding forcing factors operating at disparate timescales is essential for predicting future woody encroachment and the water and climate implications of land cover transitions.

  16. Fire and grazing influences on rates of riparian woody plant expansion along grassland streams.

    Science.gov (United States)

    Veach, Allison M; Dodds, Walter K; Skibbe, Adam

    2014-01-01

    Grasslands are threatened globally due to the expansion of woody plants. The few remaining headwater streams within tallgrass prairies are becoming more like typical forested streams due to rapid conversion of riparian zones from grassy to wooded. Forestation can alter stream hydrology and biogeochemistry. We estimated the rate of riparian woody plant expansion within a 30 m buffer zone surrounding the stream bed across whole watersheds at Konza Prairie Biological Station over 25 years from aerial photographs. Watersheds varied with respect to experimentally-controlled fire and bison grazing. Fire frequency, presence or absence of grazing bison, and the historical presence of woody vegetation prior to the study time period (a proxy for proximity of propagule sources) were used as independent variables to predict the rate of riparian woody plant expansion between 1985 and 2010. Water yield was estimated across these years for a subset of watersheds. Riparian woody encroachment rates increased as burning became less frequent than every two years. However, a higher fire frequency (1-2 years) did not reverse riparian woody encroachment regardless of whether woody vegetation was present or not before burning regimes were initiated. Although riparian woody vegetation cover increased over time, annual total precipitation and average annual temperature were variable. So, water yield over 4 watersheds under differing burn frequencies was quite variable and with no statistically significant detected temporal trends. Overall, burning regimes with a frequency of every 1-2 years will slow the conversion of tallgrass prairie stream ecosystems to forested ones, yet over long time periods, riparian woody plant encroachment may not be prevented by fire alone, regardless of fire frequency.

  17. The effects of topo-edaphic variables and cultivation on the woody ...

    African Journals Online (AJOL)

    Several, mostly Acacia, species appear to have recruited intermittently. The vegetation changes of this system will have an affect on browse availability. The woody vegetation of WNR appears to be changing in response to successional processes and management influences. Keywords: carrying capacity; classification; ...

  18. LBA-ECO ND-02 Secondary Forest Small Stem, Non-Woody Biomass, Para, Brazil: 1999-2005

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports biomass from small stems and non-woody vegetation measured from 1999 to 2005 in plots of a secondary-growth forest fertilization experiment....

  19. LBA-ECO ND-02 Secondary Forest Small Stem, Non-Woody Biomass, Para, Brazil: 1999-2005

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports biomass from small stems and non-woody vegetation measured from 1999 to 2005 in plots of a secondary-growth forest fertilization...

  20. Subpixel displacement measurement method based on the combination of particle swarm optimization and gradient algorithm

    Science.gov (United States)

    Guang, Chen; Qibo, Feng; Keqin, Ding; Zhan, Gao

    2017-10-01

    A subpixel displacement measurement method based on the combination of particle swarm optimization (PSO) and gradient algorithm (GA) was proposed for accuracy and speed optimization in GA, which is a subpixel displacement measurement method better applied in engineering practice. An initial integer-pixel value was obtained according to the global searching ability of PSO, and then gradient operators were adopted for a subpixel displacement search. A comparison was made between this method and GA by simulated speckle images and rigid-body displacement in metal specimens. The results showed that the computational accuracy of the combination of PSO and GA method reached 0.1 pixel in the simulated speckle images, or even 0.01 pixels in the metal specimen. Also, computational efficiency and the antinoise performance of the improved method were markedly enhanced.

  1. Implementation and optimization of sub-pixel motion estimation on BWDSP platform

    Science.gov (United States)

    Jia, Shangzhu; Lang, Wenhui; Zeng, Feiyang; Liu, Yufu

    2017-08-01

    Sub-pixel Motion estimation algorithm is a key technology in video coding inter-frame prediction algorithm, which has important influence on video coding performance. In the latest video coding standard H.265/HEVC, interpolation filters based on DCT are used to Sub-pixel motion estimation, but it has very high computation complexity. In order to ensure the real-time performance of hardware coding, we combine the characteristics of BWDSP architecture, using code level optimization techniques to realize the sub-pixel motion estimation algorithm. Experimental results demonstrate that In the BWDSP simulation environment, the proposed method significantly decreases the running clock cycle and thus improves the performance of the encoder.

  2. Simulating urban land cover changes at sub-pixel level in a coastal city

    Science.gov (United States)

    Zhao, Xiaofeng; Deng, Lei; Feng, Huihui; Zhao, Yanchuang

    2014-10-01

    The simulation of urban expansion or land cover changes is a major theme in both geographic information science and landscape ecology. Yet till now, almost all of previous studies were based on grid computations at pixel level. With the prevalence of spectral mixture analysis in urban land cover research, the simulation of urban land cover at sub-pixel level is being put into agenda. This study provided a new approach of land cover simulation at sub-pixel level. Landsat TM/ETM+ images of Xiamen city, China on both the January of 2002 and 2007 were used to acquire land cover data through supervised classification. Then the two classified land cover data were utilized to extract the transformation rule between 2002 and 2007 using logistic regression. The transformation possibility of each land cover type in a certain pixel was taken as its percent in the same pixel after normalization. And cellular automata (CA) based grid computation was carried out to acquire simulated land cover on 2007. The simulated 2007 sub-pixel land cover was testified with a validated sub-pixel land cover achieved by spectral mixture analysis in our previous studies on the same date. And finally the sub-pixel land cover of 2017 was simulated for urban planning and management. The results showed that our method is useful in land cover simulation at sub-pixel level. Although the simulation accuracy is not quite satisfactory for all the land cover types, it provides an important idea and a good start in the CA-based urban land cover simulation.

  3. Plant diversity and ecosystem multifunctionality peak at intermediate levels of woody cover in global drylands

    Science.gov (United States)

    Soliveres, Santiago; Maestre, Fernando T.; Eldridge, David J.; Delgado-Baquerizo, Manuel; Quero, José Luis; Bowker, Matthew A.; Gallardo, Antonio

    2015-01-01

    Aim The global spread of woody plants into grasslands is predicted to increase over the coming century. While there is general agreement regarding the anthropogenic causes of this phenomenon, its ecological consequences are less certain. We analyzed how woody vegetation of differing cover affects plant diversity (richness and evenness) and multiple ecosystem functions (multifunctionality) in global drylands, and how this changes with aridity. Location 224 dryland sites from all continents except Antarctica widely differing in their environmental conditions (from arid to dry-subhumid sites) and woody covers (from 0 to 100%). Methods Using a standardized field survey, we measured the cover, richness and evenness of perennial vegetation. At each site, we measured 14 ecosystem functions related to soil fertility and the build-up of nutrient pools. These functions are critical for maintaining ecosystem function in drylands. Results Species richness and ecosystem multifunctionality were strongly influenced by woody vegetation, with both variables peaking at relative woody covers (RWC) of 41-60%. This relationship shifted with aridity. We observed linear positive effects of RWC in dry-subhumid sites. These positive trends shifted to hump-shaped RWC-diversity and multifunctionality relationships under semiarid environments. Finally, hump-shaped (richness, evenness) or linear negative (multifunctionality) effects of RWC were found under the most arid conditions. Main conclusions Plant diversity and multifunctionality peaked at intermediate levels of woody cover, although this relationship became increasingly positive under wetter environments. This comprehensive study accounts for multiple ecosystem attributes across a range of woody covers and environmental conditions. Our results help us to reconcile contrasting views of woody encroachment found in current literature and can be used to improve predictions of the likely effects of encroachment on biodiversity and ecosystem

  4. Lidar-based Evaluation of Sub-pixel Forest Structural Characteristics and Sun-sensor Geometries that Influence MODIS Leaf Area Index Product Accuracy and Retrieval Quality

    Science.gov (United States)

    Jensen, J.; Humes, K. S.

    2010-12-01

    Leaf Area Index (LAI) is an important structural component of vegetation because the foliar surface of plants largely controls the exchange of water, nutrients, and energy within terrestrial ecosystems. Because LAI is a key variable used to model water, energy, and biogeochemical cycles, Moderate Resolution Imaging Spectroradiometer (MODIS) LAI products are widely used in many studies to better understand and quantify exchanges between the terrestrial surface and the atmosphere. Within the last decade, significant resources and efforts have been invested toward MODIS LAI validation for a variety of biome types and a suite of published work has provided valuable feedback on the agreement between MODIS-derived LAI via radiative transfer (RT) inversion compared to multispectral-based empirical estimates of LAI. Our study provides an alternative assessment of the MODIS LAI product for a 58,000 ha evergreen needleleaf forest located in the western Rocky Mountain range in northern Idaho by using lidar data to model (R2=0.86, RMSE=0.76) and map fine-scale estimates of vegetation structure over a region for which multispectral LAI estimates were unacceptable. In an effort to provide feedback on algorithm performance, we evaluated the agreement between lidar-modeled and MODIS-retrieved LAI by specific MODIS LAI retrieval algorithm and product quality definitions. We also examined the sub-pixel vegetation structural conditions and satellite-sensor geometries that tend to influence MODIS LAI retrieval algorithm and product quality over our study area. Our results demonstrate a close agreement between lidar LAI and MODIS LAI retrieved using the main RT algorithm and consistently large MODIS LAI overestimates for pixels retrieved from a saturated set of RT solutions. Our evaluation also illuminated some conditions for which sub-pixel structural characteristics and sun-sensor geometries influenced retrieval quality and product agreement. These conditions include: 1) the

  5. Radial lens distortion correction with sub-pixel accuracy for X-ray micro-tomography.

    Science.gov (United States)

    Vo, Nghia T; Atwood, Robert C; Drakopoulos, Michael

    2015-12-14

    Distortion correction or camera calibration for an imaging system which is highly configurable and requires frequent disassembly for maintenance or replacement of parts needs a speedy method for recalibration. Here we present direct techniques for calculating distortion parameters of a non-linear model based on the correct determination of the center of distortion. These techniques are fast, very easy to implement, and accurate at sub-pixel level. The implementation at the X-ray tomography system of the I12 beamline, Diamond Light Source, which strictly requires sub-pixel accuracy, shows excellent performance in the calibration image and in the reconstructed images.

  6. A sustainable woody biomass biorefinery.

    Science.gov (United States)

    Liu, Shijie; Lu, Houfang; Hu, Ruofei; Shupe, Alan; Lin, Lu; Liang, Bin

    2012-01-01

    Woody biomass is renewable only if sustainable production is imposed. An optimum and sustainable biomass stand production rate is found to be one with the incremental growth rate at harvest equal to the average overall growth rate. Utilization of woody biomass leads to a sustainable economy. Woody biomass is comprised of at least four components: extractives, hemicellulose, lignin and cellulose. While extractives and hemicellulose are least resistant to chemical and thermal degradation, cellulose is most resistant to chemical, thermal, and biological attack. The difference or heterogeneity in reactivity leads to the recalcitrance of woody biomass at conversion. A selection of processes is presented together as a biorefinery based on incremental sequential deconstruction, fractionation/conversion of woody biomass to achieve efficient separation of major components. A preference is given to a biorefinery absent of pretreatment and detoxification process that produce waste byproducts. While numerous biorefinery approaches are known, a focused review on the integrated studies of water-based biorefinery processes is presented. Hot-water extraction is the first process step to extract value from woody biomass while improving the quality of the remaining solid material. This first step removes extractives and hemicellulose fractions from woody biomass. While extractives and hemicellulose are largely removed in the extraction liquor, cellulose and lignin largely remain in the residual woody structure. Xylo-oligomers, aromatics and acetic acid in the hardwood extract are the major components having the greatest potential value for development. Higher temperature and longer residence time lead to higher mass removal. While high temperature (>200°C) can lead to nearly total dissolution, the amount of sugars present in the extraction liquor decreases rapidly with temperature. Dilute acid hydrolysis of concentrated wood extracts renders the wood extract with monomeric sugars

  7. LBA-ECO LC-15 Vegetation Cover Types from MODIS, 1-km, Amazon Basin: 2000-2001

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set contains proportional estimates for the vegetative cover types of woody vegetation, herbaceous vegetation, and bare ground over the Amazon Basin for...

  8. Subpixel urban land cover estimation: comparing cubist, random forests, and support vector regression

    Science.gov (United States)

    Jeffrey T. Walton

    2008-01-01

    Three machine learning subpixel estimation methods (Cubist, Random Forests, and support vector regression) were applied to estimate urban cover. Urban forest canopy cover and impervious surface cover were estimated from Landsat-7 ETM+ imagery using a higher resolution cover map resampled to 30 m as training and reference data. Three different band combinations (...

  9. Physical Simulator of Infrared Spectroradiometer with Spatial Resolution Enhancement Using Subpixel Image Registration and Processing

    Directory of Open Access Journals (Sweden)

    Lyalko, V.І.

    2015-11-01

    Full Text Available The mathematical and physical models of the new frame infrared spectroradiometer based on microbolometer array sensor with subpixel image registration are presented. It is planned to include the radiometer into onboard instrumentation of the future «Sich» satellite system for the land surface physical characterization by enhanced spatial resolution infrared space imagery.

  10. Sub-Pixel Magnetic Field and Plasma Dynamics Derived from Photospheric Spectral Data

    Science.gov (United States)

    Rasca, Anthony P.; Chen, James; Pevtsov, Alexei A.

    2017-08-01

    Current high-resolution observations of the photosphere show small dynamic features at the resolving limit during emerging flux events. However, line-of-sight (LOS) magnetogram pixels only contain the net uncanceled magnetic flux, which is expected to increase for fixed regions as resolution limits improve. Using a new method with spectrographic images, we quantify distortions in photospheric absorption (or emission) lines caused by sub-pixel magnetic field and plasma dynamics in the vicinity of active regions and emerging flux events. Absorption lines—quantified by their displacement, width, asymmetry, and peakedness—have previously been used with Stokes I images from SOLIS/VSM to relate line distortions with sub-pixel plasma dynamics driven by solar flares or small-scale flux ropes. The method is extended to include the full Stokes parameters and relate inferred sub-pixel dynamics with small-scale magnetic fields. Our analysis is performed on several sets of spectrographic images taken by SOLIS/VSM while observing eruptive and non-eruptive active regions. We discuss the results of this application and their relevance for understanding magnetic fields signatures and coupled plasma properties on sub-pixel scales.

  11. Exploring the limits of identifying sub-pixel thermal features using ASTER TIR data

    Science.gov (United States)

    Vaughan, R.G.; Keszthelyi, L.P.; Davies, A.G.; Schneider, D.J.; Jaworowski, C.; Heasler, H.

    2010-01-01

    Understanding the characteristics of volcanic thermal emissions and how they change with time is important for forecasting and monitoring volcanic activity and potential hazards. Satellite instruments view volcanic thermal features across the globe at various temporal and spatial resolutions. Thermal features that may be a precursor to a major eruption, or indicative of important changes in an on-going eruption can be subtle, making them challenging to reliably identify with satellite instruments. The goal of this study was to explore the limits of the types and magnitudes of thermal anomalies that could be detected using satellite thermal infrared (TIR) data. Specifically, the characterization of sub-pixel thermal features with a wide range of temperatures is considered using ASTER multispectral TIR data. First, theoretical calculations were made to define a "thermal mixing detection threshold" for ASTER, which quantifies the limits of ASTER's ability to resolve sub-pixel thermal mixing over a range of hot target temperatures and % pixel areas. Then, ASTER TIR data were used to model sub-pixel thermal features at the Yellowstone National Park geothermal area (hot spring pools with temperatures from 40 to 90 ??C) and at Mount Erebus Volcano, Antarctica (an active lava lake with temperatures from 200 to 800 ??C). Finally, various sources of uncertainty in sub-pixel thermal calculations were quantified for these empirical measurements, including pixel resampling, atmospheric correction, and background temperature and emissivity assumptions.

  12. Segmented separable footprint projector for digital breast tomosynthesis and its application for subpixel reconstruction.

    Science.gov (United States)

    Zheng, Jiabei; Fessler, Jeffrey A; Chan, Heang-Ping

    2017-03-01

    Digital forward and back projectors play a significant role in iterative image reconstruction. The accuracy of the projector affects the quality of the reconstructed images. Digital breast tomosynthesis (DBT) often uses the ray-tracing (RT) projector that ignores finite detector element size. This paper proposes a modified version of the separable footprint (SF) projector, called the segmented separable footprint (SG) projector, that calculates efficiently the Radon transform mean value over each detector element. The SG projector is specifically designed for DBT reconstruction because of the large height-to-width ratio of the voxels generally used in DBT. This study evaluates the effectiveness of the SG projector in reducing projection error and improving DBT reconstruction quality. We quantitatively compared the projection error of the RT and the SG projector at different locations and their performance in regular and subpixel DBT reconstruction. Subpixel reconstructions used finer voxels in the imaged volume than the detector pixel size. Subpixel reconstruction with RT projector uses interpolated projection views as input to provide adequate coverage of the finer voxel grid with the traced rays. Subpixel reconstruction with the SG projector, however, uses the measured projection views without interpolation. We simulated DBT projections of a test phantom using CatSim (GE Global Research, Niskayuna, NY) under idealized imaging conditions without noise and blur, to analyze the effects of the projectors and subpixel reconstruction without other image degrading factors. The phantom contained an array of horizontal and vertical line pair patterns (1 to 9.5 line pairs/mm) and pairs of closely spaced spheres (diameters 0.053 to 0.5 mm) embedded at the mid-plane of a 5-cm-thick breast tissue-equivalent uniform volume. The images were reconstructed with regular simultaneous algebraic reconstruction technique (SART) and subpixel SART using different projectors. The

  13. Nonstructural carbon in woody plants.

    Science.gov (United States)

    Dietze, Michael C; Sala, Anna; Carbone, Mariah S; Czimczik, Claudia I; Mantooth, Joshua A; Richardson, Andrew D; Vargas, Rodrigo

    2014-01-01

    Nonstructural carbon (NSC) provides the carbon and energy for plant growth and survival. In woody plants, fundamental questions about NSC remain unresolved: Is NSC storage an active or passive process? Do older NSC reserves remain accessible to the plant? How is NSC depletion related to mortality risk? Herein we review conceptual and mathematical models of NSC dynamics, recent observations and experiments at the organismal scale, and advances in plant physiology that have provided a better understanding of the dynamics of woody plant NSC. Plants preferentially use new carbon but can access decade-old carbon when the plant is stressed or physically damaged. In addition to serving as a carbon and energy source, NSC plays important roles in phloem transport, osmoregulation, and cold tolerance, but how plants regulate these competing roles and NSC depletion remains elusive. Moving forward requires greater synthesis of models and data and integration across scales from -omics to ecology.

  14. Vegetation recovery in slash-pile scars following conifer removal in a grassland-restoration experiment

    Science.gov (United States)

    Charles B. Halpern; Joseph A. Antos; Liam M. Beckman

    2014-01-01

    A principal challenge to restoring tree-invaded grasslands is the removal of woody biomass. Burning of slash piles to reduce woody residues from forest restoration practices generates intense, prolonged heating, with adverse effects on soils and vegetation. In this study, we examined vegetation responses to pile burning following tree removal from conifer-invaded...

  15. The spatial pattern and dominant drivers of woody cover change in Latin America and Caribbean from 2001 to 2010

    Science.gov (United States)

    Clark, M.; Aide, T.; Riner, G.; Redo, D.; Grau, H.; Bonilla-Moheno, M.; Lopez-Carr, D.; Levy, M.

    2011-12-01

    Change in woody vegetation (i.e., forests, shrublands) is a major component of global environmental change: it directly affects biodiversity, the global carbon budget, and ecosystem function. For several decades, remote sensing technology has been used to document deforestation in Latin America and the Caribbean (LAC), although mostly at local to regional scales (e.g., moist forests of the Amazon basin). Most studies have focused on forest loss, some local-scale studies have mapped forest recovery, with contrasting forest dynamics attributed to shifting demographic and socio-economic factors. For example, local population change (rural-urban migration) can stimulate forest recovery on abandoned land, while increasing global food demand may drive regional expansion of mechanized agriculture. However, there are no studies in LAC that simultaneously map both loss and gain in woody vegetation at continental, national, and municipality scales with consistent data sources, methods and accuracy; and thus, we lack a comprehensive assessment of the spatial distribution of woody vegetation change and the relative importance of the multi-scale drivers of this change. We overcame this limitation by producing annual land-cover maps between 2001 and 2010 for each of the >16,000 municipalities in LAC. We focused on mapping municipality-scale trends in three broad classes: woody vegetation, mixed woody/plantations, and agriculture/herbaceous vegetation. Our area estimates show that woody vegetation change during the past decade was dominated by deforestation, or loss (-541,830 km2), particularly in the Amazon basin moist forest and the tropical-subtropical Cerrado and Chaco ecoregions, where large swaths of forest have been transformed to pastures and agricultural lands. Extensive areas (362,431 km2) in LAC also gained woody vegetation, particularly in regions too dry or too steep for modern agriculture, including the desert/xeric shrub biome in NE Brazil and northern Mexico, the

  16. Savanna Land Use and its Effect on Woody Plant Species Diversity ...

    African Journals Online (AJOL)

    A study on the diversity of woody plant species of Boke salt valley landscape in a semi-arid ecosystem of Borana was conducted. The area is a volcanic crater lake with the lake at the bottom base. Vegetation of such volcanic areas is expected to develop through the process of succession over years. Line transects were laid ...

  17. A non-destructive method for quantifying small-diameter woody biomass in southern pine forests

    Science.gov (United States)

    D. Andrew Scott; Rick Stagg; Morris Smith

    2006-01-01

    Quantifying the impact of silvicultural treatments on woody understory vegetation largely has been accomplished by destructive sampling or through estimates of frequency and coverage. In studies where repeated measures of understory biomass across large areas are needed, destructive sampling and percent cover estimates are not satisfactory. For example, estimates of...

  18. Woody plant encroachment of grasslands: a comparison of terrestrial and wetland settings.

    Science.gov (United States)

    Saintilan, Neil; Rogers, Kerrylee

    2015-02-01

    A global trend of woody plant encroachment of terrestrial grasslands is co-incident with woody plant encroachment of wetland in freshwater and saline intertidal settings. There are several arguments for considering tree encroachment of wetlands in the context of woody shrub encroachment of grassland biomes. In both cases, delimitation of woody shrubs at regional scales is set by temperature thresholds for poleward extent, and by aridity within temperature limits. Latitudinal expansion has been observed for terrestrial woody shrubs and mangroves, following recent warming, but most expansion and thickening has been due to the occupation of previously water-limited grassland/saltmarsh environments. Increases in atmospheric CO₂, may facilitate the recruitment of trees in terrestrial and wetland settings. Improved water relations, a mechanism that would predict higher soil moisture in grasslands and saltmarshes, and also an enhanced capacity to survive arid conditions, reinforces local mechanisms of change. The expansion of woody shrubs and mangroves provides a negative feedback on elevated atmospheric CO₂ by increasing carbon sequestration in grassland and saltmarsh, and is a significant carbon sink globally. These broad-scale vegetation shifts may represent a new stable state, reinforced by positive feedbacks between global change drivers and endogenic mechanisms of persistence in the landscape.

  19. Robust Matching of Wavelet Features for Sub-Pixel Registration of Landsat Data

    Science.gov (United States)

    LeMoigne, Jacqueline; Netanyahu, Nathan S.; Masek, Jeffrey G.; Mount, David M.; Goward, Samuel; Zukor, Dorothy (Technical Monitor)

    2001-01-01

    For many Earth and Space Science applications, automatic geo-registration at sub-pixel accuracy has become a necessity. In this work, we are focusing on building an operational system, which will provide a sub-pixel accuracy registration of Landsat-5 and Landsat-7 data. The input to our registration method consists of scenes that have been geometrically and radiometrically corrected. Such pre-processed scenes are then geo-registered relative to a database of Landsat chips. The method assumes a transformation composed of a rotation and a translation, and utilizes rotation- and translation-invariant wavelets to extract image features that are matched using statistically robust feature matching and a generalized Hausdorff distance metric. The registration process is described and results on four Landsat input scenes of the Washington, D.C. area are presented.

  20. Sub-pixel mineral mapping using EO-1 Hyperion hyperspectral data

    OpenAIRE

    Kumar, C.; Shetty, A.; S Raval; Champatiray, P. K.; Sharma, R.

    2014-01-01

    This study describes the utility of Earth Observation (EO)-1 Hyperion data for sub-pixel mineral investigation using Mixture Tuned Target Constrained Interference Minimized Filter (MTTCIMF) algorithm in hostile mountainous terrain of Rajsamand district of Rajasthan, which hosts economic mineralization such as lead, zinc, and copper etc. The study encompasses pre-processing, data reduction, Pixel Purity Index (PPI) and endmember extraction from reflectance image of surface minerals su...

  1. Improved subpixel monitoring of seasonal snow cover: a case study in the Alps

    OpenAIRE

    Veganzones, Miguel Angel; Dalla Mura, Mauro; Dumont, Marie; Zin, Isabella; Chanussot, Jocelyn

    2014-01-01

    International audience; The snow coverage area (SCA) is one of the most important parameters for cryospheric studies. The use of remote sensing imagery can complement field measurements by providing means to derive SCA with a high temporal frequency and covering large areas. Images acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) are perhaps the most widely used data to retrieve SCA maps. Some MODIS derived algorithms are available for subpixel SCA estimation, as MODSCAG ...

  2. Variability of myocardial perfusion dark rim Gibbs artifacts due to sub-pixel shifts

    Directory of Open Access Journals (Sweden)

    Kellman Peter

    2009-05-01

    Full Text Available Abstract Background Gibbs ringing has been shown as a possible source of dark rim artifacts in myocardial perfusion studies. This type of artifact is usually described as transient, lasting a few heart beats, and localised in random segments of the myocardial wall. Dark rim artifacts are known to be unpredictably variable. This article aims to illustrate that a sub-pixel shift, i.e. a small displacement of the pixels with respect to the endocardial border, can result in different Gibbs ringing and hence different artifacts. Therefore a hypothesis for one cause of dark rim artifact variability is given based on the sub-pixel position of the endocardial border. This article also demonstrates the consequences for Gibbs artifacts when two different methods of image interpolation are applied (post-FFT interpolation, and pre-FFT zero-filling. Results Sub-pixel shifting of in vivo perfusion studies was shown to change the appearance of Gibbs artifacts. This effect was visible in the original uninterpolated images, and in the post-FFT interpolated images. The same shifted data interpolated by pre-FFT zero-filling exhibited much less variability in the Gibbs artifact. The in vivo findings were confirmed by phantom imaging and numerical simulations. Conclusion Unless pre-FFT zero-filling interpolation is performed, Gibbs artifacts are very dependent on the position of the subendocardial wall within the pixel. By introducing sub-pixel shifts relative to the endocardial border, some of the variability of the dark rim artifacts in different myocardial segments, in different patients and from frame to frame during first-pass perfusion due to cardiac and respiratory motion can be explained. Image interpolation by zero-filling can be used to minimize this dependency.

  3. Sub-pixel mineral mapping using EO-1 Hyperion hyperspectral data

    Science.gov (United States)

    Kumar, C.; Shetty, A.; Raval, S.; Champatiray, P. K.; Sharma, R.

    2014-11-01

    This study describes the utility of Earth Observation (EO)-1 Hyperion data for sub-pixel mineral investigation using Mixture Tuned Target Constrained Interference Minimized Filter (MTTCIMF) algorithm in hostile mountainous terrain of Rajsamand district of Rajasthan, which hosts economic mineralization such as lead, zinc, and copper etc. The study encompasses pre-processing, data reduction, Pixel Purity Index (PPI) and endmember extraction from reflectance image of surface minerals such as illite, montmorillonite, phlogopite, dolomite and chlorite. These endmembers were then assessed with USGS mineral spectral library and lab spectra of rock samples collected from field for spectral inspection. Subsequently, MTTCIMF algorithm was implemented on processed image to obtain mineral distribution map of each detected mineral. A virtual verification method has been adopted to evaluate the classified image, which uses directly image information to evaluate the result and confirm the overall accuracy and kappa coefficient of 68 % and 0.6 respectively. The sub-pixel level mineral information with reasonable accuracy could be a valuable guide to geological and exploration community for expensive ground and/or lab experiments to discover economic deposits. Thus, the study demonstrates the feasibility of Hyperion data for sub-pixel mineral mapping using MTTCIMF algorithm with cost and time effective approach.

  4. Improved Surface Reflectance from Remote Sensing Data with Sub-Pixel Topographic Information

    Directory of Open Access Journals (Sweden)

    Laure Roupioz

    2014-10-01

    Full Text Available Several methods currently exist to efficiently correct topographic effects on the radiance measured by satellites. Most of those methods use topographic information and satellite data at the same spatial resolution. In this study, the 30 m spatial resolution data of the Digital Elevation Model (DEM from ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer are used to account for those topographic effects when retrieving land surface reflectance from satellite data at lower spatial resolution (e.g., 1 km. The methodology integrates the effects of sub-pixel topography on the estimation of the total irradiance received at the surface considering direct, diffuse and terrain irradiance. The corrected total irradiance is then used to compute the topographically corrected surface reflectance. The proposed method has been developed to be applied on various kilometric pixel size satellite data. In this study, it was tested and validated with synthetic Landsat data aggregated at 1 km. The results obtained after a sub-pixel topographic correction are compared with the ones obtained after a pixel level topographic correction and show that in rough terrain, the sub-pixel topography correction method provides better results even if it tends to slightly overestimate the retrieved land surface reflectance in some cases.

  5. Design of interpolation functions for subpixel-accuracy stereo-vision systems.

    Science.gov (United States)

    Haller, Istvan; Nedevschi, Sergiu

    2012-02-01

    Traditionally, subpixel interpolation in stereo-vision systems was designed for the block-matching algorithm. During the evaluation of different interpolation strategies, a strong correlation was observed between the type of the stereo algorithm and the subpixel accuracy of the different solutions. Subpixel interpolation should be adapted to each stereo algorithm to achieve maximum accuracy. In consequence, it is more important to propose methodologies for interpolation function generation than specific function shapes. We propose two such methodologies based on data generated by the stereo algorithms. The first proposal uses a histogram to model the environment and applies histogram equalization to an existing solution adapting it to the data. The second proposal employs synthetic images of a known environment and applies function fitting to the resulted data. The resulting function matches the algorithm and the data as best as possible. An extensive evaluation set is used to validate the findings. Both real and synthetic test cases were employed in different scenarios. The test results are consistent and show significant improvements compared with traditional solutions. © 2011 IEEE

  6. Chave de identificação para as espécies de Dicotiledôneas arbóreas da Reserva Biológica do Tinguá, RJ, com base em caracteres vegetativos Identification key of the most common woody Dicotyledons from the Tinguá Biological Reserve (State of Rio de Janeiro, Brazil based on vegetative characters

    Directory of Open Access Journals (Sweden)

    Denise Monte Braz

    2004-06-01

    Full Text Available A Reserva Biológica do Tinguá abrange parte dos municípios de Nova Iguaçu, Duque de Caxias, Miguel Pereira e Petrópolis, localizados na região centro-oeste do Estado do Rio de Janeiro, apresentando vegetação predominantemente florestal que integra o complexo vegetacional Mata Atlântica. Embora situada próxima à área urbana, a Reserva do Tinguá apresenta desmatamento quase nulo e grande riqueza florística. Dentre os projetos realizados como parte do programa Linhas de Pesquisa em Mata Atlântica - CNPq, desenvolvida pelo Departamento de Botânica da Universidade Federal Rural do Rio de Janeiro, foi elaborada a chave para a identificação das espécies arbóreas, tendo como base características morfológicas vegetativas, tais como a filotaxia e forma das folhas, presença ou ausência de estípulas, exsudado, lenticelas, indumento e glândulas. A chave apresentada consta de 109 espécies, distribuídas em 35 famílias botânicas.The Tinguá Biological Reserve is located within the boundaries of the municipalitiesof Nova Iguaçu, Duque de Caxias, Miguel Pereira, and Petrópolis, in the central-western region of Rio de Janeiro State, Brazil. Its vegetation is mainly formed by forests belonging to the Atlantic Rain Forest Complex. Although located close to urban areas, the Tinguá Reserve has suffered little deforestation which is assured by its species richness. As one of the several projects for the Reserve, developed by the Botany Department of the Federal University of Rio de Janeiro, an identification key of the woody Dicotyledons is presented, using morphological vegetative characters such as phyllotaxy, leaf shape, stipules, exsudates, lenticells, indument, and glands. A total of 109 species can be identified, belonging to 35 families.

  7. Vegetation survey of Sengwa

    Directory of Open Access Journals (Sweden)

    G. C. Craig

    1983-12-01

    Full Text Available The approach and initial results of a vegetation survey of the Sengwa Wildlife Area are outlined. The objectives were to produce a vegetation classification and map sufficiently detailed to serve as a base for the management of the natural vegetation. The methods adopted consist of (a stratification of the area into homogeneous units using 1:10 000 colour aerial photographs; (b plotless random sampling of each stratum by recording cover abundance on the Braun-Blaunquet scale for all woody species; and (c analysis of the data by indicator species analysis using the computer programme 'Twinspan’. The classification produced is successful in achieving recognizable vegetation types which tie in well with known environmental features.

  8. Woody biomass from short rotation energy crops

    Science.gov (United States)

    R.S. Zalesny; M.W. Cunningham; R.B. Hall; J. Mirck; D.L. Rockwood; John Stanturf; T.A. Volk

    2011-01-01

    Short rotation woody crops (SRWCs) are ideal for woody biomass production and management systems because they are renewable energy feedstocks for biofuels, bioenergy, and bioproducts that can be strategically placed in the landscape to conserve soil and water, recycle nutrients, and sequester carbon. This chapter is a synthesis of the regional implications of producing...

  9. Regional Comparative Advantage for Woody Biofuels Production

    Science.gov (United States)

    Timothy M. Young; Donald G. Hodges; Robert C. Abt; Andy J. Hartsell; James H. Perdue

    2009-01-01

    The economic availability of woody biomass for the southeastern United States is summarized in this final report for the U.S. Department of Transportation, Southeastern Sun Grant Center research contract R11-0515-016 as administered by the University of Tennessee. Georeferenced economic supply curves (marginal cost curves) for woody biomass producers’ for the 13...

  10. Sustainable Biofuels from Forests: Woody Biomass

    Directory of Open Access Journals (Sweden)

    Edwin H. White

    2011-11-01

    Full Text Available The use of woody biomass feedstocks for bioenergy and bioproducts involves multiple sources of material that together create year round supplies. The main sources of woody biomass include residues from wood manufacturing industries, low value trees including logging slash in forests that are currently underutilized and dedicated short-rotation woody crops. Conceptually a ton of woody biomass feedstocks can replace a barrel of oil as the wood is processed (refined through a biorefinery. As oil is refined only part of the barrel is used for liquid fuel, e.g., gasoline, while much of the carbon in oil is refined into higher value chemical products-carbon in woody biomass can be refined into the same value-added products.

  11. Fitossociologia e similaridade florística entre trechos de Cerrado sentido restrito em interflúvio e em vale no Jardim Botânico de Brasília, DF Phytossociology and floristic similarity between plateau and valley `Cerrado` woody vegetation in the Brasília Botanic Gardens, Federal District, Brazil

    Directory of Open Access Journals (Sweden)

    Mônica Souza da Fonseca

    2004-03-01

    Full Text Available Este estudo teve como objetivo verificar a composição florística, densidade e área basal do componente lenhoso do cerrado sentido restrito em duas situações num gradiente topográfico, designadas interflúvio (I e vale (V, no Jardim Botânico de Brasília, DF. Foram alocadas em cada área 10 parcelas permanentes de 20x50m para amostragem de todos os indivíduos com diâmetro basal DB(30cm> 5cm. A classificação por UPGMA (Índices de Sørensen e Morisita foi usada para a avaliação da similaridade entre parcelas. A análise da fitossociologia mostrou que as espécies mais importantes no interflúvio foram: Ouratea hexasperma (A. St.Hil Baill., Miconia ferruginata DC. e Dalbergia miscolobium Benth., enquanto que no vale foram: Eriotheca pubescens (Mart. & Zucc. Schott & Endl., Ouratea hexasperma (A. St.-Hil. Baill. e Schefflera macrocarpa (Seem D.C. Frodin. Os índices de similaridade variaram entre 0,26 a 0,81 (Sørensen e 0,06 a 0,92 (Morisita. A classificação por UPGMA indicou dois grupos principais, que coincidiram com as posições no relevo: interflúvio e vale. Os resultados salientaram a topografia como forte determinante na distribuição de algumas das populações e comunidades lenhosas, por meio de sua influência na variação da profundidade do lençol freático, que afetou a composição florística, a densidade (I/V=1.219/956 ind.ha-1 e a área basal (I/V=8,56/5,64m².ha-1 nos Cerrados sentido restrito de interflúvio (I e vale (V estudados.This study aims to check differences in the floristic composition and structure of the woody vegetation of the cerrado (sensu stricto in two distinct topographic positions, Interfluve (I and Valley Slope (V area in the Brasília Botanic Gardens, Federal District, Brazil. In each area ten 20x50m permanent plots were located to survey individuals, basal diameter BD(30cm > 5cm. UPGMA classification (Sørensen and Morisita similarity indices was used to assess similarity among plots

  12. The influence of woody plants on the seepage of flood protection levees: Experiences from a test site

    Science.gov (United States)

    Lammeranner, W.; Meixner, H.; Florineth, F.

    2009-04-01

    The past flood events have once more drawn the attention to the stability and maintenance of flood protection levees. The attention has also been focused on the relationship between vegetation and the structural integrity of dikes. Current standards regard dense turf to be safest vegetation cover for dikes. Many guidelines ban woody vegetation from dikes and levees to provide structural integrity, visual inspection and unhindered flood-fight access. The refusal of woody plants is mainly based on the argument that root penetration of woody plants facilitates water movement along their path. Within the frame of a research project carried out by the Institute of Soil Bioengineering and Landscape Construction (University of Natural Resources and Applied Life Sciences, Vienna), focusing on woody plants on levees, the effects of small to medium growing woody (shrubby) plants on the seepage are tested. Data are drawn from two natural-scaled research levees. The homogenous levees consist of a mineral silt-sand-gravel and have a fill height of 2.7 m and a slope inclination of 2:3. The tests investigate the impact of woody plants (living brush mattress - transversal) in comparison to compact turf (jute netting mulch seeding). Measured plant parameters, characterising the vegetation structures were shoot lengths, shoot diameters, and above ground biomass. Root growth is investigated in an extra plot area allowing excavation of the plants. Percolation is monitored using seepage monitoring pipes, soil moisture sensors and soil temperature probes, which were build into the embankment during construction. The proposed contribution discusses the effects of woody plants (shrubs) on seepage of flood protection levees. Methodology of research and results after three initial seepage tests are presented.

  13. Mycorrhizal Productivity Following Woody Plant Invasion of Grassland

    Science.gov (United States)

    Boutton, T. W.; Rowe, H. I.; Ariza, M. C.; Miller, R. M.; Filley, T. R.

    2008-12-01

    . Since woody plant invasion of grasslands is one of the most significant global land cover changes occurring today, these results have important implications for understanding how this vegetation change will influence soil carbon storage and dynamics.

  14. woody vegetation status on different altitudinal gradients of an ...

    African Journals Online (AJOL)

    Olaniyi 01

    JOURNAL OF RESEARCH IN FORESTRY, WILDLIFE AND ENVIRONMENT VOLUME 8, No 1 MARCH, 2016. ISBN: 2141 – 1778 ... a nature based tourism; it takes into account the natural ..... waterfall is their natural heritage and belonged to ...

  15. Studies of the Woody Vegetation of the Welor Forest Reserve ...

    African Journals Online (AJOL)

    The Welor area has been classified as a forest reserve since 1935 while waiting for the outcome of studies for its appropriate exploitation based on its biological potential. Due to lack of information on this potential, the plant resources of this forest reserve have been used improperly and excessively. The present study aims ...

  16. Woody vegetation stocking, composition and diversity in Miombo ...

    African Journals Online (AJOL)

    Important value index of tree species ranged between 4.29 and 10.00, while Shannon Weiner index was between 2.54 and 3.04. Index of dominance in this study was between 0.03 and 0.11, while species diversity index ranged from 38.46 to 89.36 and species richness and evenness ranged between 9.65 and 21.04 and ...

  17. The contribution of woody plant materials on the several conditions in a space environment

    Science.gov (United States)

    Tomita-Yokotani, Kaori; Baba, Keiichi; Suzuki, Toshisada; Kimura, Shunta; Sato, Seigo; Katoh, Hiroshi; Abe, Yusuke; Katayama, Takeshi

    Woody plant materials have several utilization elements in our habitation environment on earth. The studies of woody plants under a space-environment in the vegetable kingdom have a high contribution to the study of various and exotic environmental responses, too. Woody plants can produce an excess oxygen, woody materials for the living cabin, and provide a biomass by cultivating crops and other species of creatures. Tree material would become to be a tool in closed bio-ecosystems such as an environment in a space. We named the trees used as material for the experiment related to space environments “CosmoBon”, small tree bonsai. Japanese cherry tree, “Sakura”, is famous and lovely tree in Japan. One species of “Sakura”, “Mamezakura, Prunus incisa”, is not only lovely tree species, but also suitable tree for the model tree of our purpose. The species of Prunus incisa is originally grown in volcano environment. That species of Sakura is originally grown on Mt. Fuji aria, oligotrophic place. We will try to build the best utilization usage of woody plant under the space environment by “Mamezakura” as a model tree. Here, we will show the importance of uniformity of materials when we will use the tree materials in a space environment. We will also discuss that tree has a high possibility of utilization under the space environments by using our several results related to this research.

  18. Trends in soil erosion and woody shrub encroachment in Ngqushwa district, Eastern Cape Province, South Africa.

    Science.gov (United States)

    Manjoro, Munyaradzi; Kakembo, Vincent; Rowntree, Kate M

    2012-03-01

    Woody shrub encroachment severely impacts on the hydrological and erosion response of rangelands and abandoned cultivated lands. These processes have been widely investigated at various spatial scales, using mostly field experimentation. The present study used remote sensing to investigate spatial and temporal patterns of soil erosion and encroachment by a woody shrub species, Pteronia incana, in a catchment in Ngqushwa district, Eastern Cape Province, South Africa between 1998 and 2008. The extreme categories of soil erosion and shrub encroachment were mapped with higher accuracy than the intermediate ones, particularly where lower spatial resolution data were used. The results showed that soil erosion in the worst category increased simultaneously with dense woody shrub encroachment on the hill slopes. This trend is related to the spatial patterning of woody shrub vegetation that increases bare soil patches--leading to runoff connectivity and concentration of overland flow. The major changes in soil erosion and shrub encroachment analysed during the 10-year period took place in the 5-9° slope category and on the concave slope form. Multi-temporal analyses, based on remote sensing, can extend our understanding of the dynamics of soil erosion and woody shrub encroachment. They may help benchmark the processes and assist in upscaling field studies.

  19. Evaluating Fourier Cross-Correlation Sub-Pixel Registration in Landsat Images

    Directory of Open Access Journals (Sweden)

    Jaime Almonacid-Caballer

    2017-10-01

    Full Text Available Multi-temporal analysis is one of the main applications of remote sensing, and Landsat imagery has been one of the main resources for many years. However, the moderate spatial resolution (30 m restricts their use for high precision applications. In this paper, we simulate Landsat scenes to evaluate, by means of an exhaustive number of tests, a subpixel registration process based on phase correlation and the upsampling of the Fourier transform. From a high resolution image (0.5 m, two sets of 121 synthetic images of fixed translations are created to simulate Landsat scenes (30 m. In this sense, the use of the point spread function (PSF of the Landsat TM (Thematic Mapper sensor in the downsampling process improves the results compared to those obtained by simple averaging. In the process of obtaining sub-pixel accuracy by upsampling the cross correlation matrix by a certain factor, the limit of improvement is achieved at 0.1 pixels. We show that image size affects the cross correlation results, but for images equal or larger than 100 × 100 pixels similar accuracies are expected. The large dataset used in the tests allows us to describe the intra-pixel distribution of the errors obtained in the registration process and how they follow a waveform instead of random/stochastic behavior. The amplitude of this waveform, representing the highest expected error, is estimated at 1.88 m. Finally, a validation test is performed over a set of sub-pixel shorelines obtained from actual Landsat-5 TM, Landsat-7 ETM+ (Enhanced Thematic Mapper Plus and Landsat-8 OLI (Operation Land Imager scenes. The evaluation of the shoreline accuracy with respect to permanent seawalls, before and after the registration, shows the importance of the registering process and serves as a non-synthetic validation test that reinforce previous results.

  20. Detection of sub-pixel fractures in X-ray dark-field tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lauridsen, Torsten; Feidenhans' l, Robert [University of Copenhagen, Niels Bohr Institute, Copenhagen (Denmark); Willner, Marian; Pfeiffer, Franz [Technische Universitaet Muenchen, Department of Physics and Institute of Medical Engineering, Garching (Germany); Bech, Martin [Lund University, Medical Radiation Physics, Lund (Sweden)

    2015-11-15

    We present a new method for detecting fractures in solid materials below the resolution given by the detector pixel size by using grating-based X-ray interferometry. The technique is particularly useful for detecting sub-pixel cracks in large samples where the size of the sample is preventing high-resolution μCT studies of the entire sample. The X-ray grating interferometer produces three distinct modality signals: absorption, phase and dark field. The method utilizes the unique scattering features of the dark-field signal. We have used tomograms reconstructed from each of the three signals to detect cracks in a model sample consisting of stearin. (orig.)

  1. Application of Somatic Embryogenesis in Woody Plants.

    Science.gov (United States)

    Guan, Yuan; Li, Shui-Gen; Fan, Xiao-Fen; Su, Zhen-Hong

    2016-01-01

    Somatic embryogenesis is a developmental process where a plant somatic cell can dedifferentiate to a totipotent embryonic stem cell that has the ability to give rise to an embryo under appropriate conditions. This new embryo can further develop into a whole plant. In woody plants, somatic embryogenesis plays a critical role in clonal propagation and is a powerful tool for synthetic seed production, germplasm conservation, and cryopreservation. A key step in somatic embryogenesis is the transition of cell fate from a somatic cell to embryo cell. Although somatic embryogenesis has already been widely used in a number of woody species, propagating adult woody plants remains difficult. In this review, we focus on molecular mechanisms of somatic embryogenesis and its practical applications in economic woody plants. Furthermore, we propose a strategy to improve the process of somatic embryogenesis using molecular means.

  2. An autocorrelation-based method for improvement of sub-pixel displacement estimation in ultrasound strain imaging.

    Science.gov (United States)

    Kim, Seungsoo; Aglyamov, Salavat R; Park, Suhyun; O'Donnell, Matthew; Emelianov, Stanislav Y

    2011-04-01

    In ultrasound strain and elasticity imaging, an accurate and cost-effective sub-pixel displacement estimator is required because strain/elasticity imaging quality relies on the displacement SNR, which can often be higher if more computational resources are provided. In this paper, we introduce an autocorrelation-based method to cost-effectively improve subpixel displacement estimation quality. To quantitatively evaluate the performance of the autocorrelation method, simulated and tissue-mimicking phantom experiments were performed. The computational cost of the autocorrelation method is also discussed. The results of our study suggest the autocorrelation method can be used for a real-time elasticity imaging system. © 2011 IEEE

  3. Sub-Pixel Classification of MODIS EVI for Annual Mappings of Impervious Surface Areas

    Directory of Open Access Journals (Sweden)

    Narumasa Tsutsumida

    2016-02-01

    Full Text Available Regular monitoring of expanding impervious surfaces areas (ISAs in urban areas is highly desirable. MODIS data can meet this demand in terms of frequent observations but are lacking in spatial detail, leading to the mixed land cover problem when per-pixel classifications are applied. To overcome this issue, this research develops and applies a spatio-temporal sub-pixel model to estimate ISAs on an annual basis during 2001–2013 in the Jakarta Metropolitan Area, Indonesia. A Random Forest (RF regression inferred the ISA proportion from annual 23 values of MODIS MOD13Q1 EVI and reference data in which such proportion was visually allocated from very high-resolution images in Google Earth over time at randomly selected locations. Annual maps of ISA proportion were generated and showed an average increase of 30.65 km2/year over 13 years. For comparison, a series of RF per-pixel classifications were also developed from the same reference data using a Boolean class constructed from different thresholds of ISA proportion. Results from per-pixel models varied when such thresholds change, suggesting difficulty of estimation of actual ISAs. This research demonstrated the advantages of spatio-temporal sub-pixel analysis for annual ISAs mapping and addresses the problem associated with definitions of thresholds in per-pixel approaches.

  4. The production of woody biomass

    Energy Technology Data Exchange (ETDEWEB)

    Faber, P.J.; van den Burg, J.

    For the production of good quality woody biomass the soil must have good structure and texture, a suitable groundwater level, and contain sufficient mineral nutrients and organic matter. The only suitable tree species are those that are cheap to cultivate, having a vigorous juvenile growth and a good capacity to resprout. So far, only poplar clones have been bred and selected for their juvenile growth and disease resistance. It is probably cheaper to establish plantations with cuttings or seed rather than with rooted young plants, as at least 10,000 plants are needed per ha to ensure optimum use is made of the available space from the outset. In the early phase the competing weeds should be removed mechanically or by chemical means: both these methods involve some risk. Heavy machines are required to harvest the crop, and these may compact the soil. Because the total above-ground biomass is harvested, the nutrient cycle is interrupted. To compensate for this, fertilizer must be applied at a minimum rate of 100 kg nitrogen per hectare per annum. It may also be advisable to use nitrogen-fixing tree species (Alnus, Robinia), or to irrigate with waste water or with liquid animal manure (both of which contain nutrient elements).

  5. Remote sensing of vegetation dynamics in drylands

    DEFF Research Database (Denmark)

    Tian, Feng; Brandt, Martin Stefan; Liu, Yi Y.

    2016-01-01

    greenness. The vegetation optical depth (VOD) derived from satellite passive microwave observations is mainly sensitive to the water content in total aboveground vegetation layer. VOD therefore provides a complementary data source to NDVI for monitoring biomass dynamics in drylands, yet further evaluations...... mass) in the semi-arid Senegalese Sahel. Results show that the magnitude and peak time of VOD are sensitive to the woody plant foliage whereas NDVI seasonality is primarily governed by the green herbaceous vegetation stratum in the study area. Moreover, VOD is found to be more robust against typical...... NDVI drawbacks of saturation effect and dependence on plant structure (herbaceous and woody compositions) across the study area when used as a proxy for vegetation productivity. Finally, both VOD and NDVI well reflect the spatial and inter-annual dynamics of the in situ green biomass data; however...

  6. Review article: Vegetative growth, reproduction, browse production ...

    African Journals Online (AJOL)

    This review deals with issues including the determinants of vegetative growth of woody plants (soil water availability, water stress, soil nutrient availability, carbohydrate reserves, plant hormones, atmospheric CO2 concentration, tree age, competition, defoliation and shoot pruning, fire pathogens, soil and climatic conditions) ...

  7. relationships between vegetation composition and environmental

    African Journals Online (AJOL)

    Preferred Customer

    3 Institute of Agronomy and Plant Breeding, Georg-August University, Göttingen, Germany. ABSTRACT: ... responsible for the spatial distribution and abundance of vegetation is useful in ecological restorations ..... CCA ordination diagram of the relationship between woody plants and environmental variables in the Borana.

  8. An Improved Estimation of Regional Fractional Woody/Herbaceous Cover Using Combined Satellite Data and High-Quality Training Samples

    Directory of Open Access Journals (Sweden)

    Xu Liu

    2017-01-01

    Full Text Available Mapping vegetation cover is critical for understanding and monitoring ecosystem functions in semi-arid biomes. As existing estimates tend to underestimate the woody cover in areas with dry deciduous shrubland and woodland, we present an approach to improve the regional estimation of woody and herbaceous fractional cover in the East Asia steppe. This developed approach uses Random Forest models by combining multiple remote sensing data—training samples derived from high-resolution image in a tailored spatial sampling and model inputs composed of specific metrics from MODIS sensor and ancillary variables including topographic, bioclimatic, and land surface information. We emphasize that effective spatial sampling, high-quality classification, and adequate geospatial information are important prerequisites of establishing appropriate model inputs and achieving high-quality training samples. This study suggests that the optimal models improve estimation accuracy (NMSE 0.47 for woody and 0.64 for herbaceous plants and show a consistent agreement with field observations. Compared with existing woody estimate product, the proposed woody cover estimation can delineate regions with subshrubs and shrubs, showing an improved capability of capturing spatialized detail of vegetation signals. This approach can be applicable over sizable semi-arid areas such as temperate steppes, savannas, and prairies.

  9. IMPACT OF Acacia drepanolobium (AN INVASIVE WOODY SPECIES ON GUM-RESIN RESOURCES AND LOCAL LIVELIHOOD IN BORANA, SOUTHERN ETHIOPIA

    Directory of Open Access Journals (Sweden)

    Ayana Abdeta

    2011-10-01

    Full Text Available We investigated the impact of Acacia drepanolobium, a species threatening rangeland resources including Gum-resin production and pastoralists’ livelihoods in Borana. Data were collected through vegetation surveys, key informant interviews, use of formal questionnaires and focus group discussions. We found a total of 22 woody species in the study area. A. drepanolobium was found to be the most dominant (22% and abundant (65% invasive woody species with an importance value index (IVI of 103. According to our respondents, A. drepanolobium was the first widely expanded woody species followed by Dichrostachys cinerea and A. mellifera. Eighty seven percent of our respondents ranked A. drepanolobium as the most invading woody species during their life time. Overall, our results demonstrated that the impact of A. drepanolobium had greatly affected the condition of rangeland vegetation. The implication is that the reduction in the capacity of rangelands for livestock grazing could reduce the resilience of local livelihood under changing environmental conditions. Furthermore, pastoralists’ perception indicated that the expansion of A. drepanolobium had reduced the survival of Gum-resin producing species. Generally, the shift from cattle based pastoral economy to mixed livestock types could be attributed to the expansion of A. drepanolobium that forced the community to shift their mode of production. We confirmed that A. drepanolobium is an invasive indigenous woody species with multiple effects on the ecology of rangelands and on the livelihood security of pastoral communities.

  10. The value of woody hedgerows for moth diversity on organic and conventional farms.

    Science.gov (United States)

    Boutin, C; Baril, A; McCabe, S K; Martin, P A; Guy, M

    2011-06-01

    Habitat destruction and degradation are important drivers of biodiversity loss within agro-ecosystems. However, little is known about the effect of farming practices and the value of woody hedgerows on Lepidoptera in North America. The purpose of this work was to study moth diversity in woody hedgerows and croplands of organic and conventional farms. In addition, the influence of vegetation composition and abiotic variables on species richness, abundance, and composition was examined. Moths were sampled with light traps during six weeks in the summer of 2001. Vegetation data and abiotic variables were obtained for all sites. In total, 26,020 individuals from 12 families and 408 species were captured. Most species were uncommon. Only 35 species included >100 individuals while for 71% of species diversity between organic and conventional farms, except that the Notodontidae were significantly more species rich in organic than in conventional sites. Results show that species richness, abundance, and composition were greatly influenced by habitat types (hedgerow versus crop field) and abiotic variables (minimum temperature which was correlated to moon illumination, rainfall, and cloud cover). Moth species composition was significantly correlated to vegetation composition. This study broadens our understanding of the factors driving moth diversity and expands our knowledge of their geographic range. The maintenance of noncrop habitats such as woody hedgerows within agro-ecosystems seems paramount to preserving the biodiversity and abundance of many organisms, including moths.

  11. Simulation of urban land surface temperature based on sub-pixel land cover in a coastal city

    Science.gov (United States)

    Zhao, Xiaofeng; Deng, Lei; Feng, Huihui; Zhao, Yanchuang

    2014-11-01

    The sub-pixel urban land cover has been proved to have obvious correlations with land surface temperature (LST). Yet these relationships have seldom been used to simulate LST. In this study we provided a new approach of urban LST simulation based on sub-pixel land cover modeling. Landsat TM/ETM+ images of Xiamen city, China on both the January of 2002 and 2007 were used to acquire land cover and then extract the transformation rule using logistic regression. The transformation possibility was taken as its percent in the same pixel after normalization. And cellular automata were used to acquire simulated sub-pixel land cover on 2007 and 2017. On the other hand, the correlations between retrieved LST and sub-pixel land cover achieved by spectral mixture analysis in 2002 were examined and a regression model was built. Then the regression model was used on simulated 2007 land cover to model the LST of 2007. Finally the LST of 2017 was simulated for urban planning and management. The results showed that our method is useful in LST simulation. Although the simulation accuracy is not quite satisfactory, it provides an important idea and a good start in the modeling of urban LST.

  12. Characterizing sub-pixel landsat ETM plus fire severity on experimental fires in the Kruger National Park, South Africa

    CSIR Research Space (South Africa)

    Landmann, T

    2003-07-01

    Full Text Available Burn severity was quantitatively mapped using a unique linear spectral mixture model to determine sub-pixel abundances of different ashes and combustion completeness measured on the corresponding fire-affected pixels in Landsat data. A new burn...

  13. Patterns of woody plant invasion in an Argentinean coastal grassland

    Science.gov (United States)

    Alberio, Constanza; Comparatore, Viviana

    2014-01-01

    Coastal dune grasslands are fragile ecosystems that have historically been subjected to various types of uses and human activities. In Buenos Aires Province (Argentina), these areas are frequently afforested for urban and touristic development. The introduction and subsequent spread of exotic tree species is one of the main threats to conservation of natural grasslands as invasive trees strongly transform their structure and composition. The aim of this study was to identify patterns of woody plant invasion comparing plant communities and environmental variables between invaded and non-invaded areas surrounding the coastal village of Mar Azul, Argentina. Coastal grasslands in this area are being invaded by Populus alba (white poplar) and Acacia longifolia (coast wattle). The height of the saplings and the richness of the accompanying vegetation were evaluated in relation to the distance from the edge of the mature tree patches. Also, the cover, richness and diversity of all species in the invaded and non-invaded areas were measured, as well as soil pH, temperature and particle size. Negative correlations were found between the height of the saplings and distance to mature tree patches in all areas. The richness of the accompanying vegetation was negatively and positively correlated with the distance from the poplar and acacia area, respectively. The most abundant native species was Cortaderia selloana. Less cover, richness and diversity of native plant species and greater soil particle size were found in invaded areas, where the proportion of bare soil was higher. Also, a higher proportion of leaf litter in the invaded areas was registered. The results emphasize the invasive capacity of P. alba and A. longifolia advancing on the native communities and reducing their richness. Knowledge of the impact of invasive woody plants in coastal grasslands is important to design active management strategies for conservation purposes.

  14. Bringing aerospace images into coincidence with subpixel accuracy by the local-correlation method

    Science.gov (United States)

    Potapov, A. S.; Malyshev, I. A.; Lutsiv, V. R.

    2004-05-01

    This paper proposes a local-correlation method that makes it possible to bring aerospace images into coincidence with subpixel accuracy after preliminary rough juxtaposition by transforming them relative to each other by uniform projective transformation and by additional mutual local displacements. The basis of the method is to establish a correspondence between the points of a pair of images by means of a phase correlation of individual segments of the images. The dissemination of information concerning measured shifts from reference points for which the correspondence has been found on a pair of images, as well as the use of analysis with variable spatial resolution, makes the method workable when the errors of the preliminary superposition are greater than the size of the correlation window. This paper presents the results of an experimental verification of the approach, using actual pairs of aerospace images as an example.© 2004

  15. Sub-pixel estimation of tree cover and bare surface densities using regression tree analysis

    Directory of Open Access Journals (Sweden)

    Carlos Augusto Zangrando Toneli

    2011-09-01

    Full Text Available Sub-pixel analysis is capable of generating continuous fields, which represent the spatial variability of certain thematic classes. The aim of this work was to develop numerical models to represent the variability of tree cover and bare surfaces within the study area. This research was conducted in the riparian buffer within a watershed of the São Francisco River in the North of Minas Gerais, Brazil. IKONOS and Landsat TM imagery were used with the GUIDE algorithm to construct the models. The results were two index images derived with regression trees for the entire study area, one representing tree cover and the other representing bare surface. The use of non-parametric and non-linear regression tree models presented satisfactory results to characterize wetland, deciduous and savanna patterns of forest formation.

  16. Height to Live Crown of Vegetation in Acadia National Park (acad_ht_crwn)

    Data.gov (United States)

    National Park Service, Department of the Interior — This is a raster dataset in which cell values represent average height to live crown base, in feet, of woody terrestrial vegetation in Acadia National Park.

  17. Architecture-Driven Level Set Optimization: From Clustering to Subpixel Image Segmentation.

    Science.gov (United States)

    Balla-Arabe, Souleymane; Gao, Xinbo; Ginhac, Dominique; Brost, Vincent; Yang, Fan

    2016-12-01

    Thanks to their effectiveness, active contour models (ACMs) are of great interest for computer vision scientists. The level set methods (LSMs) refer to the class of geometric active contours. Comparing with the other ACMs, in addition to subpixel accuracy, it has the intrinsic ability to automatically handle topological changes. Nevertheless, the LSMs are computationally expensive. A solution for their time consumption problem can be hardware acceleration using some massively parallel devices such as graphics processing units (GPUs). But the question is: which accuracy can we reach while still maintaining an adequate algorithm to massively parallel architecture? In this paper, we attempt to push back the compromise between, speed and accuracy, efficiency and effectiveness, to a higher level, comparing with state-of-the-art methods. To this end, we designed a novel architecture-aware hybrid central processing unit (CPU)-GPU LSM for image segmentation. The initialization step, using the well-known k -means algorithm, is fast although executed on a CPU, while the evolution equation of the active contour is inherently local and therefore suitable for GPU-based acceleration. The incorporation of local statistics in the level set evolution allowed our model to detect new boundaries which are not extracted by the used clustering algorithm. Comparing with some cutting-edge LSMs, the introduced model is faster, more accurate, less subject to giving local minima, and therefore suitable for automatic systems. Furthermore, it allows two-phase clustering algorithms to benefit from the numerous LSM advantages such as the ability to achieve robust and subpixel accurate segmentation results with smooth and closed contours. Intensive experiments demonstrate, objectively and subjectively, the good performance of the introduced framework both in terms of speed and accuracy.

  18. Subpixel boundary backward substitution reconstruction algorithm for not uniform microscan to FPA and blind micromotion matching

    Science.gov (United States)

    Chen, Yi-nan; Jin, Wei-qi; Zhao, Lei; Gao, Mei-jing; Zhao, Lin

    2008-03-01

    For the subpixel micro-scanning imaging, we propose the reconstruction algorithm based on neither interpolation nor super-resolution idea but one of the block-by-block method recursive from the boundary to centre when additional narrowband boundary view-field diaphragm whose radiation is known a prior. The aim of the predicted boundary value is to add the conditions for solving the ununiqueness ill-problem to the inverse transition matrix from the destructed process. For the non-uniform scan factor, the improved algorithm associated with certain non-uniform motion variables is proposed. Additionally, attention is focused on the case of unknown subpixel motion, when the reconstructed images are blurred by motion parameter modulation and neighbouring point aliasing because the value of micro-motion is not the correct one. Unlike other methods that the image registration is accomplished before multi-frame restoration from undersampled sequences frame by frame, in this paper, 2-D motion vector is estimated in single frame just from the blur character of reconstructed grids. We demonstrate that once the estimated motion approaches to the real one, square summation of all pixels over the unmatched image approximately descends to the minimum. The matching track based on recursive Newton secant approaching is optimized for high matching speed and precision by different strategies, including matching region hunting, matching direction choosing and convergence prejudgement. All iterative step lengths with respect to motion parameters are substituted by the suitable values derived from the statistic process and one or multi-secant solution. The simulations demonstrate the feasibility of the matching algorithm and the obvious resolution enhancement compared to the direct oversampling image.

  19. Hyper-Temporal C-Band SAR for Baseline Woody Structural Assessments in Deciduous Savannas

    Directory of Open Access Journals (Sweden)

    Russell Main

    2016-08-01

    Full Text Available Savanna ecosystems and their woody vegetation provide valuable resources and ecosystem services. Locally calibrated and cost effective estimates of these resources are required in order to satisfy commitments to monitor and manage change within them. Baseline maps of woody resources are important for analyzing change over time. Freely available, and highly repetitive, C-band data has the potential to be a viable alternative to high-resolution commercial SAR imagery (e.g., RADARSAT-2, ALOS2 in generating large-scale woody resources maps. Using airborne LiDAR as calibration, we investigated the relationships between hyper-temporal C-band ASAR data and woody structural parameters, namely total canopy cover (TCC and total canopy volume (TCV, in a deciduous savanna environment. Results showed that: the temporal filter reduced image variance; the random forest model out-performed the linear model; while the TCV metric consistently showed marginally higher accuracies than the TCC metric. Combinations of between 6 and 10 images could produce results comparable to high resolution commercial (C- & L-band SAR imagery. The approach showed promise for producing a regional scale, locally calibrated, baseline maps for the management of deciduous savanna resources, and lay a foundation for monitoring using time series of data from newer C-band SAR sensors (e.g., Sentinel1.

  20. Exploiting differential vegetation phenology for satellite-based mapping of semiarid grass vegetation in the southwestern United States and northern Mexico

    Science.gov (United States)

    Dye, Dennis G.; Middleton, Barry R.; Vogel, John M.; Wu, Zhuoting; Velasco, Miguel G.

    2016-01-01

    We developed and evaluated a methodology for subpixel discrimination and large-area mapping of the perennial warm-season (C4) grass component of vegetation cover in mixed-composition landscapes of the southwestern United States and northern Mexico. We describe the methodology within a general, conceptual framework that we identify as the differential vegetation phenology (DVP) paradigm. We introduce a DVP index, the Normalized Difference Phenometric Index (NDPI) that provides vegetation type-specific information at the subpixel scale by exploiting differential patterns of vegetation phenology detectable in time-series spectral vegetation index (VI) data from multispectral land imagers. We used modified soil-adjusted vegetation index (MSAVI2) data from Landsat to develop the NDPI, and MSAVI2 data from MODIS to compare its performance relative to one alternate DVP metric (difference of spring average MSAVI2 and summer maximum MSAVI2), and two simple, conventional VI metrics (summer average MSAVI2, summer maximum MSAVI2). The NDPI in a scaled form (NDPIs) performed best in predicting variation in perennial C4 grass cover as estimated from landscape photographs at 92 sites (R2 = 0.76, p vegetation types in other regions where the vegetation components of the landscape exhibit contrasting seasonal patterns of phenology.

  1. Comparative analysis of woody plants biomass on the affected and ...

    African Journals Online (AJOL)

    There are differences in woody plant distribution and sizes on the affected and restricted land management practices in rural areas. The aim of the study is to determine the difference in woody plants biomass on the adopted land management practices. The data required are distribution, height and girth of woody plant ...

  2. Urban tree and woody yard residues : another wood resource

    Science.gov (United States)

    David B. McKeever; Kenneth E. Skog

    2003-01-01

    Urban tree and woody yard residues are an important component of the municipal solid waste (MSW) stream in the United States. In 2000, approximately 14.5 million tons of urban tree and woody yard residues was generated, nearly 7% of total MSW. Some woody residues are being recovered for recycling, composting, or other uses, but a large proportion is simply discarded....

  3. 48 CFR 1452.237-71 - Utilization of Woody Biomass.

    Science.gov (United States)

    2010-10-01

    ... Biomass. 1452.237-71 Section 1452.237-71 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR... Utilization of Woody Biomass. As prescribed in § 1437.7202, insert the following clause: Utilization of Woody Biomass (MAY 2005) (a) The contractor may remove and utilize woody biomass, if: (1) Project work is...

  4. Satellite- and pollen-based quantitative woody cover reconstructions for northern Asia: Verification and application to late-Quaternary pollen data

    Science.gov (United States)

    Tarasov, Pavel; Williams, John W.; Andreev, Andrei; Nakagawa, Takeshi; Bezrukova, Elena; Herzschuh, Ulrike; Igarashi, Yaeko; Müller, Stefanie; Werner, Kirstin; Zheng, Zhuo

    2007-12-01

    Accurate reconstruction of late-Quaternary vegetation cover is necessary for better understanding of past vegetation dynamics, the role of vegetation feedbacks in glacial-interglacial climate variations, and for validating vegetation and climate models. In this paper over 1700 surface-pollen spectra from the former Soviet Union, Mongolia, northern China, and northern Japan together with data from the Advanced Very High Resolution Radiometer (AVHRR) were used to calibrate modern-analogue method for quantitatively reconstructing past woody cover from fossil pollen data. The AVHRR-based estimates of woody cover percentages within a 21 × 21 km window around pollen sampling sites were attributed to the respective modern pollen spectra. Reconstructions of modern woody cover using the pollen data and best-modern-analogues (BMA) method matched well to the original AVHRR-based estimates, for both total woody cover ( r2 = 0.77) and its fractions, including broad-leaved ( r2 = 0.66), needle-leaved ( r2 = 0.79), deciduous ( r2 = 0.60) and evergreen ( r2 = 0.76) woody cover. Discrepancies in the pollen-AVHRR cross-validation may be caused by long-distance transport of arboreal pollen, patchy forest distributions, underrepresentation of Larix and Populus in pollen records, and errors in the AVHRR classification. The generally strong correlations encourage application of the modern-analogue approach for reconstructing late-Quaternary variations in vegetation cover from northern Asian fossil pollen records. At the last glacial maximum (LGM: ˜ 21,000 cal yr BP), areas presently occupied by boreal forest were much more open, suggesting a reduction in total woody cover to below 20% at most modern forest sites. Pollen records from northern and central Siberia suggest a rather quick spread of tree and shrub vegetation after 15,000 cal yr BP, presumably in response to increased summer insolation. Woody cover histories are spatially variable in the modern forest-steppe, where tree

  5. Extreme low temperature tolerance in woody plants

    Science.gov (United States)

    G. Richard Strimbeck; Paul G. Schaberg; Carl G. Fossdal; Wolfgang P. Schroder; Trygve D. Kjellsen

    2015-01-01

    Woody plants in boreal to arctic environments and high mountains survive prolonged exposure to temperatures below -40°C and minimum temperatures below -60°C, and laboratory tests show that many of these species can also survive immersion in liquid nitrogen at -196°C. Studies of biochemical changes that occur during acclimation, including recent proteomic and...

  6. Forest biodiversity and woody biomass harvesting

    Science.gov (United States)

    Deahn M. Donner; T. Bently Wigley; Darren A. Miller

    2017-01-01

    With the expected increase in demand for woody biomass to help meet renewable energy needs, one principal sustainability question has been whether this material can be removed from forest stands while still conserving biological diversity and retaining ecosystem functioning (Hecht et al. 2009; Berch, Morris, and Malcolm 2011; Ridley et al. 2013). In general,...

  7. Determinants of woody cover in African savannas

    NARCIS (Netherlands)

    Sankaran, M.; Hanan, N.P.; Scholes, R.J.; Ratnam, J.; Augustine, D.J.; Cade, B.S.; Gignoux, J.; Higgins, S.I.; Roux, Le X.; Ludwig, F.; Ardo, J.; Banyikwa, F.; Bronn, A.; Bicini, G.; Caylor, K.K.; Coughenour, M.B.; Diouf, A.; Ekaya, W.; Feral, C.J.; February, E.C.; Frost, P.G.H.; Hiernaux, P.; Hrabar, H.; Metzger, K.L.; Prins, H.H.T.; Ringrose, S.; Sea, W.; Tews, J.; Worden, J.; Zambatis, N.

    2005-01-01

    Savannas are globally important ecosystems of great significance to human economies. In these biomes, which are characterized by the co-dominance of trees and grasses, woody cover is a chief determinant of ecosystem properties 1-3. The availability of resources (water, nutrients) and disturbance

  8. Effect of Woody Debris abundance on daytime refuge use by cotton mice.

    Energy Technology Data Exchange (ETDEWEB)

    Hinkelman, Travis, M.; Loeb, Susan, C.

    2007-07-01

    Abstract - Daytime refuges are important to nocturnal rodents for protection from predators and environmental extremes. Because refuges of forest-dwelling rodents are often associated with woody debris, we examined refuge use by 37 radio-collared Peromyscus gossypinus (cotton mice) in experimental plots with different levels of woody debris. Treatment plots had six times (≈ 60 m3/ha) the volume of woody debris as control plots (≈ 10 m3/ha). Of 247 refuges, 159 were in rotting stumps (64%), 32 were in root boles (13%), 19 were in brush piles (8%), and 16 were in logs (6%); 10 refuges could not be identified. Stumps were the most common refuge type in both treatments, but the distribution of refuge types was significantly different between treatment and control plots. Root boles and brush piles were used more on treatment plots than on control plots, and logs were used more on control plots than on treatment plots. Refuge type and vegetation cover were the best predictors of refuge use by cotton mice; root bole refuges and refuges with less vegetation cover received greater-than-expected use by mice. Abundant refuges, particularly root boles, may improve habitat quality for cotton mice in southeastern pine forests.

  9. Decadal shifts in grass and woody plant cover are driven by prolonged drying and modified by topo-edaphic properties.

    Science.gov (United States)

    Munson, Seth M; Sankey, Temuulen T; Xian, George; Villarreal, Miguel L; Homer, Collin G

    2016-12-01

    Woody plant encroachment and overall declines in perennial vegetation in dryland regions can alter ecosystem properties and indicate land degradation, but the causes of these shifts remain controversial. Determining how changes in the abundance and distribution of grass and woody plants are influenced by conditions that regulate water availability at a regional scale provides a baseline to compare how management actions alter the composition of these vegetation types at a more local scale and can be used to predict future shifts under climate change. Using a remote-sensing-based approach, we assessed the balance between grasses and woody plants and how climate and topo-edaphic conditions affected their abundances across the northern Sonoran Desert from 1989 to 2009. Despite widespread woody plant encroachment in this region over the last 150 years, we found that leguminous trees, including mesquite (Prosopis spp.), declined in cover in areas with prolonged drying conditions during the early 21st century. Creosote bush (Larrea tridentata) also had moderate decreases with prolonged drying but was buffered from changes on soils with low clay that promote infiltration and high available water capacity that allows for retention of water at depth. Perennial grasses have expanded and contracted over the last two decades in response to summer precipitation and were especially dynamic on shallow soils with high clay that have large fluctuations in water availability. Our results suggest that topo-edaphic properties can amplify or ameliorate climate-induced changes in woody plants and perennial grasses. Understanding these relationships has important implications for ecosystem function under climate change in the southwestern USA and can inform management efforts to regulate grass and woody plant abundances. © 2016 by the Ecological Society of America.

  10. Patterns of Woody Growth for Brazilian Savanna (Cerrado) Trees in the Cuiaba Basin and Pantanal of Mato Grosso, Brazil

    Science.gov (United States)

    Zappia, A. J.; Vourlitis, G. L.; Pinto-Jr, O. B.

    2015-12-01

    The Brazilian savanna, locally known as cerrado, is a major ecosystem that covers a vast majority of central Brazil. Little is known about how woody growth within the cerrado is affected by soil properties such as texture and/or nutrient availability. Thus, in this study we assessed the relationship between woody growth and soil properties in the Cuiaba Basin and Pantanal of Mato Grosso, Brazil. We sampled 4-5 vegetation stands in each site that varied in hydrology, soil type, and vegetation composition and structure, and measured diameter at breast height, wood density, and soil nutrient concentration and physical properties every 5-10 m along a 100 m long transect. We hypothesized that as tree diameter at breast height increases, annual tree growth rate will decrease and that woody carbon (C) storage will increase as a function of soil nutrient availability. Our preliminary data support our hypotheses. Tree growth rates declined with tree size in both the Cuiaba Basin and the Pantanal. Rates of woody C storage, both on a per tree basis (kgC tree-1 year-1) and on a per unit ground area basis (kgC m-2 year-1) were significantly positively correlated with soil extractable phosphorus (P), calcium (Ca), and clay content, while only woody C storage on a per tree basis was positively correlated with potassium (K), magnesium (Mg), and cation exchange capacity (CEC). These data suggest that rates of woody C storage in cerrado are nutrient limited, while correspondence between C storage and soil physical properties could indicate both nutrient and water limitations to C storage.

  11. Changes in soil nitrogen storage and δ15N with woody plant encroachment in a subtropical savanna parkland landscape

    Science.gov (United States)

    Boutton, T. W.; Liao, J. D.

    2010-09-01

    Subtropical woodlands dominated by N-fixing tree legumes have largely replaced grasslands in the Rio Grande Plains, southwestern United States, during the past century. To evaluate the impact of this vegetation change on the N cycle, we measured the mass and isotopic composition (δ15N) of N in the soil system of remnant grasslands and woody plant stands ranging in age from 10 to 130 years. Nitrogen accumulated at linear rates following woody encroachment in the litter (0.10-0.14 g N m-2 yr-1), roots (0.63-0.98 g N m-2 yr-1), and soils (0.75-3.50 g N m-2 yr-1), resulting in a 50%-150% increase in N storage in the soil system (0-30 cm) in woody stands older than 60 years. Simultaneous decreases in soil δ15N of up to 2‰ in the upper 30 cm of the profile are consistent with a scenario in which N inputs have exceeded losses following woody encroachment and suggest N accrual was derived from symbiotic N fixation by tree legumes and/or differential atmospheric N deposition to wooded areas. Vertical uplift and lateral transfer of N by the more deeply and intensively rooted woody plants may have contributed to N accumulation in wooded areas, but soil δ15N values are inconsistent with this explanation. N accumulation following woody encroachment may alter soil N availability, species interactions and successional dynamics, flux rates of key trace gases such as NOX and N2O and ecosystem C sequestration. Given the geographic dimensions of woody encroachment, these results may have implications for atmospheric composition and the climate system.

  12. Sub-pixel measurement system for grid's width and period based on an improved partial area effect

    Science.gov (United States)

    Zhu, Feijia; Jin, Peng

    2017-12-01

    Based on the partial area effect of charge-coupled device (CCD), a sub-pixel line detecting algorithm is proposed to measure the width and the period of a metal grid. An optical pointing system is developed and applied to accurately measure the line-width and the period of a grid. The grid's moving image is captured by the developed system. From the obtained images, one can determine position of a line with sub-pixel resolution. By controlling the grid's movement and aiming at the grid, the absolute coordinates of a grating ruler are obtained. Simulated calculations and experiments are performed with recorded video images to validate the performance of the proposed algorithm. The results show that the precision of the proposed estimation algorithm can reach 0.025 pixels for a moving image.

  13. Woodiness within the Spermacoceae-Knoxieae alliance (Rubiaceae): retention of the basal woody condition in Rubiaceae or recent innovation?

    Science.gov (United States)

    Lens, Frederic; Groeninckx, Inge; Smets, Erik; Dessein, Steven

    2009-05-01

    The tribe Spermacoceae is essentially a herbaceous Rubiaceae lineage, except for some species that can be described as 'woody' herbs, small shrubs to treelets, or lianas. Its sister tribe Knoxieae contains a large number of herbaceous taxa, but the number of woody taxa is higher compared to Spermacoceae. The occurrence of herbaceous and woody species within the same group raises the question whether the woody taxa are derived from herbaceous taxa (i.e. secondary woodiness), or whether woodiness represents the ancestral state (i.e. primary woodiness). Microscopic observations of wood anatomy are combined with an independent molecular phylogeny to answer this question. Observations of wood anatomy of 21 woody Spermacoceae and eight woody Knoxieae species, most of them included in a multi-gene molecular phylogeny, are carried out using light microscopy. Observations of wood anatomy in Spermacoceae support the molecular hypothesis that all the woody species examined are secondary derived. Well-known wood anatomical characters that demonstrate this shift from the herbaceous to the woody habit are the typically flat or decreasing length vs. age curves for vessel elements, the abundance of square and upright ray cells, or even the (near-) absence of rays. These so-called paedomorphic wood features are also present in the Knoxieae genera Otiophora, Otomeria, Pentas, Pentanisia and Phyllopentas. However, the wood structure of the other Knoxieae genera observed (Carphalea, Dirichletia and Triainolepis) is typical of primarily woody taxa. In Spermacoceae, secondary woodiness has evolved numerous times in strikingly different habitats. In Knoxieae, there is a general trend from primary woodiness towards herbaceousness and back to (secondary) woodiness.

  14. DONUTS: A science frame autoguiding algorithm with sub-pixel precision, capable of guiding on defocused stars

    OpenAIRE

    McCormac, J.; Pollacco, D.; Skillen, I.; Faedi, F.; Todd, I.; Watson, C. A.

    2013-01-01

    We present the DONUTS autoguiding algorithm, designed to fix stellar positions at the sub-pixel level for high-cadence time-series photometry, which is also capable of autoguiding on defocused stars. DONUTS was designed to calculate guide corrections from a series of science images and re-centre telescope pointing between each exposure. The algorithm has the unique ability of calculating guide corrections from under-sampled to heavily defocused point spread functions. We present the case for ...

  15. Quantifying Sub-Pixel Surface Water Coverage in Urban Environments Using Low-Albedo Fraction from Landsat Imagery

    OpenAIRE

    Weiwei Sun; Bo Du; Shaolong Xiong

    2017-01-01

    The problem of mixed pixels negatively affects the delineation of accurate surface water in Landsat Imagery. Linear spectral unmixing has been demonstrated to be a powerful technique for extracting surface materials at a sub-pixel scale. Therefore, in this paper, we propose an innovative low albedo fraction (LAF) method based on the idea of unconstrained linear spectral unmixing. The LAF stands on the “High Albedo-Low Albedo-Vegetation” model of spectral unmixing analysis in urban environment...

  16. Subpixel Snow Cover Mapping from MODIS Data by Nonparametric Regression Splines

    Science.gov (United States)

    Akyurek, Z.; Kuter, S.; Weber, G. W.

    2016-12-01

    Spatial extent of snow cover is often considered as one of the key parameters in climatological, hydrological and ecological modeling due to its energy storage, high reflectance in the visible and NIR regions of the electromagnetic spectrum, significant heat capacity and insulating properties. A significant challenge in snow mapping by remote sensing (RS) is the trade-off between the temporal and spatial resolution of satellite imageries. In order to tackle this issue, machine learning-based subpixel snow mapping methods, like Artificial Neural Networks (ANNs), from low or moderate resolution images have been proposed. Multivariate Adaptive Regression Splines (MARS) is a nonparametric regression tool that can build flexible models for high dimensional and complex nonlinear data. Although MARS is not often employed in RS, it has various successful implementations such as estimation of vertical total electron content in ionosphere, atmospheric correction and classification of satellite images. This study is the first attempt in RS to evaluate the applicability of MARS for subpixel snow cover mapping from MODIS data. Total 16 MODIS-Landsat ETM+ image pairs taken over European Alps between March 2000 and April 2003 were used in the study. MODIS top-of-atmospheric reflectance, NDSI, NDVI and land cover classes were used as predictor variables. Cloud-covered, cloud shadow, water and bad-quality pixels were excluded from further analysis by a spatial mask. MARS models were trained and validated by using reference fractional snow cover (FSC) maps generated from higher spatial resolution Landsat ETM+ binary snow cover maps. A multilayer feed-forward ANN with one hidden layer trained with backpropagation was also developed. The mutual comparison of obtained MARS and ANN models was accomplished on independent test areas. The MARS model performed better than the ANN model with an average RMSE of 0.1288 over the independent test areas; whereas the average RMSE of the ANN model

  17. Activities of Extracellular Enzymes in Soils Following Woody Plant Invasion of Grassland

    Science.gov (United States)

    Filley, T. R.; Stott, D. E.; Dooling, V.; Sorg, L.; Boutton, T.

    2008-12-01

    Extracellular enzymes produced by microbes and immobilize in the soil environment are the principle means by which complex plant and microbial compounds are degraded. The concentration of these enzymes and their ability to interact with litter and soil organic matter contributes both to the stabilization and destabilization of soil carbon. We quantified the activities of three extracellular enzymes, B-glucosidase, B- glucosaminidase, polyphenol oxidase (PPO), and a general marker for hydrolytic activity through fluorescein diacetate (FDA) hydrolysis activity, in a subtropical savanna parkland in southern Texas where woody plants have invaded a once open grassland. Previous research has demonstrated that areas which have shifted to woody vegetation are accruing soil carbon, undergoing a dramatic shift in the chemistry of plant input, and increasing in hyphal biomass. Soils were obtained along a successional chronosequence from grassland dominated by C4 grasses to woody patches dominated by C3 trees/shrubs in Oct 2006 and stored immediately frozen until thawing for enzyme assay. Most enzymes, with the exception of PPO, show distinct behavior when comparing grassland and clusters in that grasslands exhibit far lower mass normalized activity than clusters and no activity trend with respect to age of the adjacent cluster. Both FDA and B- glucosaminidase activities are positively correlated with the age of the woody clusters and increase their activity by as much as 10-fold across the age gradient from 14 yr to 86 yr old clusters. The cellulose degrading enzyme, B-glucosidase, always exhibited greater activity (1.5 -4 fold) in woody clusters than in grasslands, but did not exhibit a trend with increasing cluster age. The PPO activity is anomalous in that there is no quantitative difference in mass normalized activity between grassland and cluster and no trend with cluster age. The results for the FDA and B-glucosaminidase assays are consistent with concurrent studies

  18. Sparrow nest survival in relation to prescribed fire and woody plant invasion in a northern mixed-grass prairie

    Science.gov (United States)

    Murphy, Robert K.; Shaffer, Terry L.; Grant, Todd A.; Derrig, James L.; Rubin, Cory S.; Kerns, Courtney K.

    2017-01-01

    Prescribed fire is used to reverse invasion by woody vegetation on grasslands, but managers often are uncertain whether influences of shrub and tree reduction outweigh potential effects of fire on nest survival of grassland birds. During the 2001–2003 breeding seasons, we examined relationships of prescribed fire and woody vegetation to nest survival of clay-colored sparrow (Spizella pallida) and Savannah sparrow (Passerculus sandwichensis) in mixed-grass prairie at Des Lacs National Wildlife Refuge in northwestern North Dakota, USA. We assessed relationships of nest survival to 1) recent fire history, in terms of number of breeding seasons (2, 3, or 4–5) since the last prescribed fire, and 2) prevalence of trees and tall (>1.5 m) shrubs in the landscape and of low (≤1.5 m) shrubs within 5 m of nests. Nest survival of both species exhibited distinct patterns related to age of the nest and day of year, but bore no relationship to fire history. Survival of clay-colored sparrow nests declined as the amount of trees and tall shrubs within 100 m increased, but we found no relationship to suggest nest parasitism by brown-headed cowbirds (Molothrus ater) as an underlying mechanism. We found little evidence linking nest survival of Savannah sparrow to woody vegetation. Our results suggest that fire can be used to restore northern mixed-grass prairies without adversely affecting nest survival of ≥2 widespread passerine species. Survival of nests of clay-colored sparrow may increase when tall woody cover is reduced by fire. Our data lend support to the use of fire for reducing scattered patches of tall woody cover to enhance survival of nests of ≥1 grassland bird species in northern mixed-grass prairies, but further study is needed that incorporates experimental approaches and assessments of shorter term effects of fire on survival of nests of grassland passerines.

  19. Ecosystem Impacts of Woody Encroachment In Texas: A Spatial Analysis Using AVIRIS

    Science.gov (United States)

    Martin, Roberta E.; Asner, Gregory P.

    2004-01-01

    Woody encroachment, the increase of woody plant density relative to herbaceous vegetation, has been documented in drylands of Texas as well as worldwide (Archer 1994, Harrington and Harman 1995, Moleele et al. 2002). Over-grazing, fire suppression and climate change are implicated in the shift from open grasslands to ecosystems now populated by trees and shrubs (Scholes and Archer 1997, Archer et al. 2001), such as Prosopis glandulosa var. glandulosa (honey mesquite) in north Texas (Teague et al. 1997, Ansley et al. 2001, Asner et al. 2003a). Several studies have examined changes in ecosystem properties accompanying woody vegetation encroachment in the Southwest U.S., with research focused on increases in plant and soil carbon (C) and nitrogen (N) stores (Hoffman and Jackson 2000, Asner et al. 2003a), isotopic shifts in these pools (Boutton 1999, Archer et al. 2001), and increases in N cycling rates (Rundel et al. 1982, Hibbard et al. 2001). However, little is known regarding the impact of woody encroachment on N trace gas emissions from dryland regions such as Texas. NOx is produced in the soil during the processes of nitrification and denitrification (Firestone and Davidson 1989). The total N efflux from soils is most directly influenced by the internal cycling of N, which at a regionalscale, is controlled by the inputs and availability of N from vegetation via litterfall and subsequent decomposition (Robertson et al. 1989). Although plot-scale studies are critical to understanding controls over N oxide emissions, regionalization of the measurements is impeded by spatial variation in the factors contributing most to N cycling processes: soil properties (affecting soil moisture regimes and N stocks) and vegetation cover (affecting litter inputs and N uptake). While broad patterns in ecosystem structure and vegetation composition co-vary with general patterns of trace gas emissions (Matson 1997), there is no easily measured index of N availability that can be

  20. Shortcut in DIC error assessment induced by image interpolation used for subpixel shifting

    Science.gov (United States)

    Bornert, Michel; Doumalin, Pascal; Dupré, Jean-Christophe; Poilane, Christophe; Robert, Laurent; Toussaint, Evelyne; Wattrisse, Bertrand

    2017-04-01

    In order to characterize errors of Digital Image Correlation (DIC) algorithms, sets of virtual images are often generated from a reference image by in-plane sub-pixel translations. This leads to the determination of the well-known S-shaped bias error curves and their corresponding random error curves. As images are usually shifted by using interpolation schemes similar to those used in DIC algorithms, the question of the possible bias in the quantification of measurement uncertainties of DIC softwares is raised and constitutes the main problematic of this paper. In this collaborative work, synthetic numerically shifted images are built from two methods: one based on interpolations of the reference image and the other based on the transformation of an analytic texture function. Images are analyzed using an in-house subset-based DIC software and results are compared and discussed. The effect of image noise is also highlighted. The main result is that the a priori choices to numerically shift the reference image modify DIC results and may lead to wrong conclusions in terms of DIC error assessment.

  1. Real-time subpixel-accuracy tracking of single mitochondria in neurons reveals heterogeneous mitochondrial motion.

    Science.gov (United States)

    Alsina, Adolfo; Lai, Wu Ming; Wong, Wai Kin; Qin, Xianan; Zhang, Min; Park, Hyokeun

    2017-11-04

    Mitochondria are essential for cellular survival and function. In neurons, mitochondria are transported to various subcellular regions as needed. Thus, defects in the axonal transport of mitochondria are related to the pathogenesis of neurodegenerative diseases, and the movement of mitochondria has been the subject of intense research. However, the inability to accurately track mitochondria with subpixel accuracy has hindered this research. Here, we report an automated method for tracking mitochondria based on the center of fluorescence. This tracking method, which is accurate to approximately one-tenth of a pixel, uses the centroid of an individual mitochondrion and provides information regarding the distance traveled between consecutive imaging frames, instantaneous speed, net distance traveled, and average speed. Importantly, this new tracking method enables researchers to observe both directed motion and undirected movement (i.e., in which the mitochondrion moves randomly within a small region, following a sub-diffusive motion). This method significantly improves our ability to analyze the movement of mitochondria and sheds light on the dynamic features of mitochondrial movement. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Fuzzy neural network model for the estimation of subpixel land cover composition

    Science.gov (United States)

    Binaghi, Elisabetta; Brivio, Pietro A.; Ghezzi, Pier P.; Rampini, Anna; Vicenzi, Massimo

    1998-12-01

    This paper reports on an experimental study designed for the in-depth investigation of how a supervised neuro-fuzzy classifier evaluates partial membership in land cover classes. The system is based on the Fuzzy Multilayer Perceptron model proposed by Pal and Mitra to which modifications in distance measures adopted for computing gradual membership to fuzzy class are introduced. During the training phase supervised learning is used to assign output class membership to pure training vectors (full membership to one land cover class); the model supports a procedure to automatically compute fuzzy output membership values for mixed training pixels. The classifier has been evaluated by conducting two experiments. The first employed simulated tests images which include pure and mixed pixels of known geometry and radiometry. The second experiment was conducted on a highly complex real scene of the Venice lagoon, Italy) where water and wetland merge into one another, at sub-pixel level. Accuracy of the results produced by the classifier was evaluated and compared using evaluation tools specifically defined and implemented to extend conventional descriptive and analytical statistical estimators to the case of multi-membership in classes. Results obtained demonstrated in the specific context of mixed pixels that the classification benefits from the integration of neural and fuzzy techniques.

  3. Parametric Study to Improve Subpixel Accuracy of Nitric Oxide Tagging Velocimetry with Image Preprocessing

    Directory of Open Access Journals (Sweden)

    Ravi Teja Vedula

    2017-01-01

    Full Text Available Biacetyl phosphorescence has been the commonly used molecular tagging velocimetry (MTV technique to investigate in-cylinder flow evolution and cycle-to-cycle variations in an optical engine. As the phosphorescence of biacetyl tracer deteriorates in the presence of oxygen, nitrogen was adopted as the working medium in the past. Recently, nitrous oxide MTV technique was employed to measure the velocity profile of an air jet. The authors here plan to investigate the potential application of this technique for engine flow studies. A possible experimental setup for this task indicated different permutations of image signal-to-noise ratio (SNR and laser line width. In the current work, a numerical analysis is performed to study the effect of these two factors on displacement error in MTV image processing. Also, several image filtering techniques were evaluated and the performance of selected filters was analyzed in terms of enhancing the image quality and minimizing displacement errors. The flow displacement error without image preprocessing was observed to be inversely proportional to SNR and directly proportional to laser line width. The mean filter resulted in the smallest errors for line widths smaller than 9 pixels. The effect of filter size on subpixel accuracy showed that error levels increased as the filter size increased.

  4. Sub-pixel localisation of passive micro-coil fiducial markers in interventional MRI.

    Science.gov (United States)

    Rea, Marc; McRobbie, Donald; Elhawary, Haytham; Tse, Zion T H; Lamperth, Michael; Young, Ian

    2009-04-01

    Electromechanical devices enable increased accuracy in surgical procedures, and the recent development of MRI-compatible mechatronics permits the use of MRI for real-time image guidance. Integrated imaging of resonant micro-coil fiducials provides an accurate method of tracking devices in a scanner with increased flexibility compared to gradient tracking. Here we report on the ability of ten different image-processing algorithms to track micro-coil fiducials with sub-pixel accuracy. Five algorithms: maximum pixel, barycentric weighting, linear interpolation, quadratic fitting and Gaussian fitting were applied both directly to the pixel intensity matrix and to the cross-correlation matrix obtained by 2D convolution with a reference image. Using images of a 3 mm fiducial marker and a pixel size of 1.1 mm, intensity linear interpolation, which calculates the position of the fiducial centre by interpolating the pixel data to find the fiducial edges, was found to give the best performance for minimal computing power; a maximum error of 0.22 mm was observed in fiducial localisation for displacements up to 40 mm. The inherent standard deviation of fiducial localisation was 0.04 mm. This work enables greater accuracy to be achieved in passive fiducial tracking.

  5. A Robust Subpixel Motion Estimation Algorithm Using HOS in the Parametric Domain

    Directory of Open Access Journals (Sweden)

    E. M. Ismaili Aalaoui

    2009-02-01

    Full Text Available Motion estimation techniques are widely used in todays video processing systems. The most frequently used techniques are the optical flow method and phase correlation method. The vast majority of these algorithms consider noise-free data. Thus, in the case of the image sequences are severely corrupted by additive Gaussian (perhaps non-Gaussian noises of unknown covariance, the classical techniques will fail to work because they will also estimate the noise spatial correlation. In this paper, we have studied this topic from a viewpoint different from the above to explore the fundamental limits in image motion estimation. Our scheme is based on subpixel motion estimation algorithm using bispectrum in the parametric domain. The motion vector of a moving object is estimated by solving linear equations involving third-order hologram and the matrix containing Dirac delta function. Simulation results are presented and compared to the optical flow and phase correlation algorithms; this approach provides more reliable displacement estimates particularly for complex noisy image sequences. In our simulation, we used the database freely available on the web.

  6. A Robust Subpixel Motion Estimation Algorithm Using HOS in the Parametric Domain

    Directory of Open Access Journals (Sweden)

    Ibn-Elhaj E

    2009-01-01

    Full Text Available Motion estimation techniques are widely used in todays video processing systems. The most frequently used techniques are the optical flow method and phase correlation method. The vast majority of these algorithms consider noise-free data. Thus, in the case of the image sequences are severely corrupted by additive Gaussian (perhaps non-Gaussian noises of unknown covariance, the classical techniques will fail to work because they will also estimate the noise spatial correlation. In this paper, we have studied this topic from a viewpoint different from the above to explore the fundamental limits in image motion estimation. Our scheme is based on subpixel motion estimation algorithm using bispectrum in the parametric domain. The motion vector of a moving object is estimated by solving linear equations involving third-order hologram and the matrix containing Dirac delta function. Simulation results are presented and compared to the optical flow and phase correlation algorithms; this approach provides more reliable displacement estimates particularly for complex noisy image sequences. In our simulation, we used the database freely available on the web.

  7. Subpixelic Measurement of Large 1D Displacements: Principle, Processing Algorithms, Performances and Software

    Science.gov (United States)

    Guelpa, Valérian; Laurent, Guillaume J.; Sandoz, Patrick; Zea, July Galeano; Clévy, Cédric

    2014-01-01

    This paper presents a visual measurement method able to sense 1D rigid body displacements with very high resolutions, large ranges and high processing rates. Sub-pixelic resolution is obtained thanks to a structured pattern placed on the target. The pattern is made of twin periodic grids with slightly different periods. The periodic frames are suited for Fourier-like phase calculations—leading to high resolution—while the period difference allows the removal of phase ambiguity and thus a high range-to-resolution ratio. The paper presents the measurement principle as well as the processing algorithms (source files are provided as supplementary materials). The theoretical and experimental performances are also discussed. The processing time is around 3 μs for a line of 780 pixels, which means that the measurement rate is mostly limited by the image acquisition frame rate. A 3-σ repeatability of 5 nm is experimentally demonstrated which has to be compared with the 168 μm measurement range. PMID:24625736

  8. Mixture-Tuned, Clutter Matched Filter for Remote Detection of Subpixel Spectral Signals

    Science.gov (United States)

    Thompson, David R.; Mandrake, Lukas; Green, Robert O.

    2013-01-01

    Mapping localized spectral features in large images demands sensitive and robust detection algorithms. Two aspects of large images that can harm matched-filter detection performance are addressed simultaneously. First, multimodal backgrounds may thwart the typical Gaussian model. Second, outlier features can trigger false detections from large projections onto the target vector. Two state-of-the-art approaches are combined that independently address outlier false positives and multimodal backgrounds. The background clustering models multimodal backgrounds, and the mixture tuned matched filter (MT-MF) addresses outliers. Combining the two methods captures significant additional performance benefits. The resulting mixture tuned clutter matched filter (MT-CMF) shows effective performance on simulated and airborne datasets. The classical MNF transform was applied, followed by k-means clustering. Then, each cluster s mean, covariance, and the corresponding eigenvalues were estimated. This yields a cluster-specific matched filter estimate as well as a cluster- specific feasibility score to flag outlier false positives. The technology described is a proof of concept that may be employed in future target detection and mapping applications for remote imaging spectrometers. It is of most direct relevance to JPL proposals for airborne and orbital hyperspectral instruments. Applications include subpixel target detection in hyperspectral scenes for military surveillance. Earth science applications include mineralogical mapping, species discrimination for ecosystem health monitoring, and land use classification.

  9. Vegetation Plot Data of the Coastal Wetland Elevation Monitoring Sites on National Wildlife Refuges in the South Atlantic Geography.

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Plot level raw datasets--including Cover, Woody Stem, Plot/Environmental, and Soil--from vegetation sampling on Coastal Wetland Elevation Monitoring Sites within the...

  10. Woody debris flow behavior from experimental analysis

    Science.gov (United States)

    Bateman, Allen; Medina, Vicente; Morloti, Emanuele; Renaud, Alexis

    2010-05-01

    A consequence of debris flow in streams are well known, the collapse of the stream flooding all over the land. The high momentum flux of those flows can devastate houses, drag and crushes cars, etc. The presence of woody debris into the flow rise the flow depth and increment the collapse of the streams, bridges and structures. The present preliminary study offer a qualitative comparison between a debris flow and a woody debris flow with similar flow characteristics. To obtain this a series of experiments were performed in the Morph-dynamic Laboratory of the Hydraulic, Marine and Environmental Department. A high slope flume of 9 meters length, 40 cm width and 60 cm high was used. Up to 5 experiments were running in the flume. Initially the material was placed dry in the bed conforming a 20 cm depth of granular material changing the way of water wave entrance. Always water wave was introduced as a step function with different step size and different flow duration in order to introduce the same volume of water, just enough to saturate all the material in the channel. The flow was filmed with a handycam in order to see the general flow characteristics and with a high speed camera, just in a section, to visualize the flow velocities. Several woody pieces were placed along the channel to simulate the presence of wood and tress in the stream. Each tree was constructed in such a way that each one have a root made by rocks simulating a real root and different mass distribution. The comparison with experiments without wood was clever to understand the influence of woods in the debris flow. The woody debris flow alone creates natural dams along the stream without presence of inciters obstacles along the reach.

  11. Ecosystem services of woody crop production systems

    Science.gov (United States)

    Ronald S. Zalesny Jr.; John A. Stanturf; Emile S. Gardiner; James H. Perdue; Timothy M. Young; David R. Coyle; William L. Headlee; Gary S. Ba??uelos; Amir Hass

    2016-01-01

    Short-rotation woody crops are an integral component of regional and national energy portfolios, as well as providing essential ecosystem services such as biomass supplies, carbon sinks, clean water, and healthy soils. We review recent USDA Forest Service Research and Development efforts from the USDA Biomass Research Centers on the provisioning of these ecosystem...

  12. [Ecological protection of medicinal woody plants].

    Science.gov (United States)

    Yan, Xiufeng

    2003-09-01

    Medicinal woody plants, especially medicinal tall trees, play a same important role in forest structure, ecological balance and timber production as other tree species in forest, and due to their additional medicinal values overuse of these trees is more intensive than others. Many medicinal materials are destructively obtained from plants such as roots or bark used as medicinal materials. The contradiction between the utilization and protection of medicinal woody plants becomes more and more incisive. In the present paper, based on the analysis of the utilized situation and specialty of medicinal woody plants, the trouble between the plants protection and utilization was observed, the method to solve it and the fundamental research work needs to be developed were discussed. The following aspects of researches were suggested to be conducted: (a) study on the distribution in organs, seasonal and age variations, and correlation with environmental factors of principal medicinal compositions in mature trees to clear the optimum of harvest and cultivation conditions; (b) study on the distribution in organs, seasonal and age variations, and correlation with environmental factors of principal medicinal compositions in saplings, especially the time course of the variation in medicinal compositions and biomass to achieve the optimal tree ages for the balance between biomass and production of medicinal products during saplings development; (c) study on the influence and regulation of environmental factors on medicinal compounds production in woody plants to look for the optimal cultivated conditions for optimizing the accumulation of biomass and medicinal chemicals; (d) further study on the regulatory mechanism of the induced production of main medicinal compositions by ecological factors at protein (key enzyme) and gene level to accumulate fundamental data for the enhancement of quality and quantity, and approach of new accesses to medicinal products using biological

  13. Modelling woody material transport and deposition in alpine rivers

    OpenAIRE

    B. Mazzorana; J. Hübl; Zischg, Andreas Paul; Largiader, A.

    2011-01-01

    Recent flood events in Switzerland and Western Austria in 2005 were characterised by an increase in impacts and associated losses due to the transport of woody material. As a consequence, protection measures and bridges suffered considerable damages. Furthermore, cross-sectional obstructions due to woody material entrapment caused unexpected flood plain inundations resulting in severe damage to elements at risk. Until now, the transport of woody material is neither sufficiently taken in...

  14. IMPACT OF WOODY PLANTS SPECIES ON SOIL PHYSIO-CHEMICAL PROPERTIES ALONG GRAZING GRADIENTS IN RANGELANDS OF EASTERN ETHIOPIA

    Directory of Open Access Journals (Sweden)

    Mohammed Mussa Abdulahi

    2016-12-01

    Full Text Available In the lowlands of arid and semiarid rangelands woody plants plays an important role in soil fertility maintenance, providing food, medicine, cosmetics, fodder, fuel wood and pesticides. A better understanding of the interaction of woody plants on their immediate environment is needed to guide optimum management of native vegetation in the production landscapes. However, the impact of woody plant species on soil properties remains poorly understood. This study evaluates the impact of two dominant woody plant species (A. senegal and B. aegyptica on soil physico-chemical properties along grazing gradients in rangelands of eastern Ethiopia. Six trees of each species were selected from light, moderate and heavy grazing sites.  Soil sample data at two depths (0-15 and 16-30 cm were collected from under and open areas of A. senegal and B. aegyptica from each grazing sites, and analysed for nutrient contents. The nutrient status of soil under both woody species was significantly higher especially with regard to soil organic matter (4.37%, total nitrogen (0.313%, and available phosphorus (11.62 than the open grassland with soil organic matter (3.82%, total nitrogen (0.246%, and available phosphorus (10.94 mg/Kg soil for A. Senegal. The soil organic matter (3.93%, total nitrogen (0.285%, available phosphorus (11.66 mg/Kg soil were significantly higher than open grassland with soil organic matter (3.52%, total nitrogen (0.218%, available phosphorus (10.73 mg/Kg soil for B. aegyptica. This was more pronounced in the top 15 cm of soil under A. senegal woody plant species and on the light and moderate grazing site. Therefore, this tree has a significant effect on soil fertility improvement in resource poor rangelands and as a result, it is important to retain scattered A. senegal and B. aegyptica plants in the lowlands of eastern Ethiopia.

  15. Facilitation between woody and herbaceous plants that associate with arbuscular mycorrhizal fungi in temperate European forests.

    Science.gov (United States)

    Veresoglou, Stavros D; Wulf, Monika; Rillig, Matthias C

    2017-02-01

    In late-successional environments, low in available nutrient such as the forest understory, herbaceous plant individuals depend strongly on their mycorrhizal associates for survival. We tested whether in temperate European forests arbuscular mycorrhizal (AM) woody plants might facilitate the establishment of AM herbaceous plants in agreement with the mycorrhizal mediation hypothesis. We used a dataset spanning over 400 vegetation plots in the Weser-Elbe region (northwest Germany). Mycorrhizal status information was obtained from published resources, and Ellenberg indicator values were used to infer environmental data. We carried out tests for both relative richness and relative abundance of herbaceous plants. We found that the subset of herbaceous individuals that associated with AM profited when there was a high cover of AM woody plants. These relationships were retained when we accounted for environmental filtering effects using path analysis. Our findings build on the existing literature highlighting the prominent role of mycorrhiza as a coexistence mechanism in plant communities. From a nature conservation point of view, it may be possible to promote functional diversity in the forest understory through introducing AM woody trees in stands when absent.

  16. Inventory of Green Spaces and Woody Plants in the Urban Landscape in Ariogala

    Directory of Open Access Journals (Sweden)

    Lina Straigytė

    2012-12-01

    Full Text Available Background and Purpose: Regulation of urban greenery design, management and protection was approved in 2008 in Lithuania after the Green Space Law was passed, allowing protection of public green spaces and woody plants. Protection of these resources first requires an inventory, and we have created a digital database that will help in management of urban green spaces. Material and Methods: An inventory of green spaces and woody plants was conducted in the public urban territory of Ariogala, using GIS technology. A digital cartographic database was created using ArcGis 9.1 software. Results and Conclusion: Most of the woody plants in the survey area are deciduous trees, and the survey results highlighted the major green space management problems. Often, planted trees grow under power lines, and their crowns touch the power cables. Near blocks of flats, trees are often in the wrong place-planted too close to buildings, trees shade windows and their roots heave pavers and penetrate building foundations. According to the inventory, street trees sustain the most damage, most commonly showing injuries on their trunks and roots. Leaves of Aesculus hipocastanum L. show massive damage from Cameraria ohridella Deschka & Dimić, and Tilia cordata Mill. are damaged by Cercospora microsora Sacc. T. cordata is a favourite city tree, but is susceptible to infestation and when damaged appears unsightly, ending its vegetation period very early. The inventory of green spaces also showed that there are sufficient public parks.

  17. Sentinel-2’s Potential for Sub-Pixel Landscape Feature Detection

    Directory of Open Access Journals (Sweden)

    Julien Radoux

    2016-06-01

    Full Text Available Land cover and land use maps derived from satellite remote sensing imagery are critical to support biodiversity and conservation, especially over large areas. With its 10 m to 20 m spatial resolution, Sentinel-2 is a promising sensor for the detection of a variety of landscape features of ecological relevance. However, many components of the ecological network are still smaller than the 10 m pixel, i.e., they are sub-pixel targets that stretch the sensor’s resolution to its limit. This paper proposes a framework to empirically estimate the minimum object size for an accurate detection of a set of structuring landscape foreground/background pairs. The developed method combines a spectral separability analysis and an empirical point spread function estimation for Sentinel-2. The same approach was also applied to Landsat-8 and SPOT-5 (Take 5, which can be considered as similar in terms of spectral definition and spatial resolution, respectively. Results show that Sentinel-2 performs consistently on both aspects. A large number of indices have been tested along with the individual spectral bands and target discrimination was possible in all but one case. Overall, results for Sentinel-2 highlight the critical importance of a good compromise between the spatial and spectral resolution. For instance, the Sentinel-2 roads detection limit was of 3 m and small water bodies are separable with a diameter larger than 11 m. In addition, the analysis of spectral mixtures draws attention to the uneven sensitivity of a variety of spectral indices. The proposed framework could be implemented to assess the fitness for purpose of future sensors within a large range of applications.

  18. Thorough statistical comparison of machine learning regression models and their ensembles for sub-pixel imperviousness and imperviousness change mapping

    Science.gov (United States)

    Drzewiecki, Wojciech

    2017-12-01

    We evaluated the performance of nine machine learning regression algorithms and their ensembles for sub-pixel estimation of impervious areas coverages from Landsat imagery. The accuracy of imperviousness mapping in individual time points was assessed based on RMSE, MAE and R2. These measures were also used for the assessment of imperviousness change intensity estimations. The applicability for detection of relevant changes in impervious areas coverages at sub-pixel level was evaluated using overall accuracy, F-measure and ROC Area Under Curve. The results proved that Cubist algorithm may be advised for Landsat-based mapping of imperviousness for single dates. Stochastic gradient boosting of regression trees (GBM) may be also considered for this purpose. However, Random Forest algorithm is endorsed for both imperviousness change detection and mapping of its intensity. In all applications the heterogeneous model ensembles performed at least as well as the best individual models or better. They may be recommended for improving the quality of sub-pixel imperviousness and imperviousness change mapping. The study revealed also limitations of the investigated methodology for detection of subtle changes of imperviousness inside the pixel. None of the tested approaches was able to reliably classify changed and non-changed pixels if the relevant change threshold was set as one or three percent. Also for fi ve percent change threshold most of algorithms did not ensure that the accuracy of change map is higher than the accuracy of random classifi er. For the threshold of relevant change set as ten percent all approaches performed satisfactory.

  19. Earth Observation of Vegetation Dynamics in Global Drylands

    DEFF Research Database (Denmark)

    Tian, Feng

    and exploring the widely used long-term datasets and 2) mapping trends in woody vegetation. A highlight of the thesis is the mapping of trends in the non-green woody vegetation component in global tropical drylands, which is obtained for the first time from combing satellite optical and passive microwave......Land degradation in global drylands has been a concern related to both the local livelihoods and the changes in terrestrial biosphere, especially in the context of substantial global environmental changes. Earth Observation (EO) provides a unique way to assess the vegetation dynamics over the past...... decades, which are keys to understanding the changes in global drylands. However, there are still large uncertainties and unknowns in the quality and capabilities of remote sensing data. This thesis contributes to an improved EO based assessment of dryland vegetation dynamics by 1) evaluating...

  20. Exotic woody plant invaders of the Transvaal

    Directory of Open Access Journals (Sweden)

    L. Henderson

    1984-12-01

    Full Text Available The frequency and abundance o ;f exotic, woody plant invaders were recorded in 60% of the quarter degree squares in the study area. Sixty-one invaders were encountered o f which the most important and aggressive were Acacia dealbaia, Populus spp.,  Melia azedarach, Opuntia ficus-indica, Salix babylonica and  Acacia mearnsii. Invasion patterns are discussed and an attempt is made to correlate distribution with environmental factors. Attention is drawn to the areas of greatest invasion and the areas that are liable to show the greatest expansion in the future.

  1. Determinants of woody cover in African savannas

    CSIR Research Space (South Africa)

    Sankaran, M

    2005-12-08

    Full Text Available explained an additional 10% of the variance in woody cover. LETTERS NATURE|Vol 438|8 December 2005 848 ? 2005 Nature Publishing Group n ? 383) of monthly mean rainfall for Africa from the ANU-CRES (ref. 20; http...://www.ncgia.ucsb.edu/conf/SANTA_FE_CD-ROM/santa_fe.html and http://cres.anu.edu.au/outputs/africa.php). Fire-return periods were obtained from field records (n ? 182) and from burnt-area maps of Africa at 5-km resolution (n ? 670) derived from AVHRR (advanced very high resolution radiometer) images based on 8 yr...

  2. Woody Allen, serial schlemiel ?

    Directory of Open Access Journals (Sweden)

    Frédérique Brisset

    2011-04-01

    Full Text Available Woody Allen a développé au fil des années une persona cinématographique de schlemiel new-yorkais aisément reconnaissable par le spectateur. Elle marque nombre de ses films, qu’il y apparaisse en tant qu’acteur ou y dirige des substituts comédiens comme déclinaisons de lui-même. Si cette figure prototypique est le fondement de la sérialité dans sa filmographie, il est des traits stylistiques qui en portent trace tout au long de son œuvre : la récurrence annuelle de ses réalisations, la signature formelle symbolisée par ses génériques à la typographie singulière, le rythme de ses dialogues ponctués d’interjections et l’usage de l’autocitation sont autant de procédés qui marquent son cinéma d’un sceau très personnel. Ils fonctionnent comme des clins d’œil au spectateur qui reçoit dès lors LE Woody Allen millésimé comme une invitation à retrouver son microcosme. Ainsi la sérialité se pose comme à la fois initiale et conséquentielle de son système filmique, processus de création unique dans le cinéma américain.Woody Allen has long constructed a cinematographic persona of schlemiel New- Yorker that the audience can easily identify. It impacts most of his films, whether he stars in them or directs “substitute” actors to impersonate his character. If this prototypical figure is the basis of seriality in his cinematography, serial stylistic features can also be found all along his career: the annual recurrence of his productions, the formal signature symbolised by the typography of his singular credit titles, his rhythmical interjection-punctuated dialogues and the use of self-quotation imprint a very personal seal upon his movies. They all work as a recognition signals for the audience who thus receive THE Woody Allen vintage as an invitation to re-enter his microcosm. Seriality is then both initial and consequential to his cinematographic system, a unique creative process in American film history.

  3. DONUTS: A Science Frame Autoguiding Algorithm with Sub-Pixel Precision, Capable of Guiding on Defocused Stars

    Science.gov (United States)

    McCormac, J.; Pollacco, D.; Skillen, I.; Faedi, F.; Todd, I.; Watson, C. A.

    2013-05-01

    We present the DONUTS autoguiding algorithm, designed to fix stellar positions at the sub-pixel level for high-cadence time-series photometry, and also capable of autoguiding on defocused stars. DONUTS was designed to calculate guide corrections from a series of science images and recentre telescope pointing between each exposure. The algorithm has the unique ability of calculating guide corrections from undersampled to heavily defocused point spread functions. We present the case for why such an algorithm is important for high precision photometry and give our results from off and on-sky testing. We discuss the limitations of DONUTS and the facilities where it soon will be deployed.

  4. Response of Competing Vegetation to Site Preparation on West Gulf Coastal Plain Commercial Forest Land

    Science.gov (United States)

    Gale L. Wolters; Henry A. Pearson; Ronald E. Thill; V. Clark Baldwin; Alton Martin

    1995-01-01

    The response of woody and herbaceous vegetation to site preparation, subsoil texture, and fertilization was measured on the West Gulf Coastal Plain. The influences of these treatments on competing vegetation were short-term. Drastic soil disturbance and fertilization briefly increased herbage production. Shear-windrow and shear-disk were generally the most effective...

  5. Herbivores shape woody plant communities in the Kruger National Park: Lessons from three long-term exclosures

    Directory of Open Access Journals (Sweden)

    Benjamin J. Wigley

    2014-02-01

    Full Text Available The role of grazers in determining vegetation community compositions and structuring plant communities is well recognised in grassy systems. The role of browsers in affecting savanna woody plant communities is less clear. We used three long-term exclosures in the Kruger National Park to determine the effect of browsers on species compositions and population structures of woody communities. Species assemblages, plant traits relating to browsing and soil nutrients were compared inside and outside of the exclosures. Our results showed that browsers directly impact plant species distributions, densities and population structures by actively selecting for species with traits which make them desirable to browsers. Species with high leaf nitrogen, low total phenolic content and low acid detergent lignin appeared to be favoured by herbivores and therefore tend to be rare outside of the exclosures. This study also suggested that browsers have important indirect effects on savanna functioning, as the reduction of woody cover can result in less litter of lower quality, which in turn can result in lower soil fertility. However, the magnitude of browser effects appeared to depend on inherent soil fertility and climate.Conservation implications: Browsers were shown to have significant impacts on plant communities. They have noticeable effects on local species diversity and population structure, as well as soil nutrients. These impacts are shown to be related to the underlying geology and climate. The effects of browsers on woody communities were shown to be greater in low rainfall, fertile areas compared to high rainfall, infertile soils.

  6. Combining woody biomass for combustion with green waste composting: Effect of removal of woody biomass on compost quality.

    Science.gov (United States)

    Vandecasteele, Bart; Boogaerts, Christophe; Vandaele, Elke

    2016-12-01

    The question was tackled on how the green waste compost industry can optimally apply the available biomass resources for producing both bioenergy by combustion of the woody fraction, and high quality soil improvers as renewable sources of carbon and nutrients. Compost trials with removal of woody biomass before or after composting were run at 9 compost facilities during 3 seasons to include seasonal variability of feedstock. The project focused on the changes in feedstock and the effect on the end product characteristics (both compost and recovered woody biomass) of this woody biomass removal. The season of collection during the year clearly affected the biochemical and chemical characteristics of feedstock, woody biomass and compost. On one hand the effect of removal of the woody fraction before composting did not significantly affect compost quality when compared to the scenario where the woody biomass was sieved from the compost at the end of the composting process. On the other hand, quality of the woody biomass was not strongly affected by extraction before or after composting. The holocellulose:lignin ratio was used in this study as an indicator for (a) the decomposition potential of the feedstock mixture and (b) to assess the stability of the composts at the end of the process. Higher microbial activity in green waste composts (indicated by higher oxygen consumption) and thus a lower compost stability resulted in higher N immobilization in the compost. Removal of woody biomass from the green waste before composting did not negatively affect the compost quality when more intensive composting was applied. The effect of removal of the woody fraction on the characteristics of the green waste feedstock and the extracted woody biomass is depending on the season of collection. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Quantitative description of woody plant communities: Part I. An ...

    African Journals Online (AJOL)

    Various descriptive units for woody plant communities are proposed. These are the evapotranspiration tree equivalent (ETTE), browse tree equivalent (BTE) and canopied subhabitat index (CSI), which describe the status of woody community in terms of potential moisture use, value of the trees as food for browsers and ...

  8. Relations between woody and herbaceous components and the ...

    African Journals Online (AJOL)

    RE.; The relations between woody and herbaceous plants in southern African savannas are reviewed in the context of pastoral use. Current knowledge is summarized, important gaps are indicated and research priorities are suggested. Although all savannas consist of a grass and a woody component, the physical ...

  9. Determinants of woody encroachment and cover in African savannas.

    Science.gov (United States)

    Devine, Aisling P; McDonald, Robbie A; Quaife, Tristan; Maclean, Ilya M D

    2017-04-01

    Savanna ecosystems are an integral part of the African landscape and sustain the livelihoods of millions of people. Woody encroachment in savannas is a widespread phenomenon but its causes are widely debated. We review the extensive literature on woody encroachment to help improve understanding of the possible causes and to highlight where and how future scientific efforts to fully understand these causes should be focused. Rainfall is the most important determinant of maximum woody cover across Africa, but fire and herbivory interact to reduce woody cover below the maximum at many locations. We postulate that woody encroachment is most likely driven by CO 2 enrichment and propose a two-system conceptual framework, whereby mechanisms of woody encroachment differ depending on whether the savanna is a wet or dry system. In dry savannas, the increased water-use efficiency in plants relaxes precipitation-driven constraints and increases woody growth. In wet savannas, the increase of carbon allocation to tree roots results in faster recovery rates after disturbance and a greater likelihood of reaching sexual maturity. Our proposed framework can be tested using a mixture of experimental and earth observational techniques. At a local level, changes in precipitation, burning regimes or herbivory could be driving woody encroachment, but are unlikely to be the explanation of this continent-wide phenomenon.

  10. Woody biomass from short rotation energy crops. Chapter 2

    Science.gov (United States)

    R.S., Jr. Zalesny Jr.; M.W. Cunningham; R.B. Hall; J. Mirck; D.L. Rockwood; J.A. Stanturf; T.A. Volk

    2011-01-01

    Short rotation woody crops (SRWCs) are ideal for woody biomass production and management systems because they are renewable energy feedstocks for biofuels, bioenergy, and bioproducts that can be strategically placed in the landscape to conserve soil and water, recycle nutrients, and sequester carbon. This chapter is a synthesis of the regional implications of producing...

  11. Sensitivity Analysis of Down Woody Material Data Processing Routines

    Science.gov (United States)

    Christopher W. Woodall; Duncan C. Lutes

    2005-01-01

    Weight per unit area (load) estimates of Down Woody Material (DWM) are the most common requests by users of the USDA Forest Service's Forest Inventory and Analysis (FIA) program's DWM inventory. Estimating of DWM loads requires the uniform compilation of DWM transect data for the entire United States. DWM weights may vary by species, level of decay, woody...

  12. Germination frequency of woody species in exotic plantation and ...

    African Journals Online (AJOL)

    ... 21-year old exotic plantations and a bush fallow land use system at Forestry Institute of Nigeria (FRIN) Umuahia, Abia State, the germination of indigenous woody species and litterfall were monitored. Enumeration of indigenous woody species was carried out within a 3.5 x 3.5 quadrat plot. The Pine/Gmelina mixed stand ...

  13. Early deterioration of coarse woody debris.

    Energy Technology Data Exchange (ETDEWEB)

    Tainter, Frank, H.; McMinn, James, W.

    1999-02-16

    Tainter, F.H., and J.W. McMinn. 1999. Early deterioration of coarse woody debris. In: Proc. Tenth Bien. South. Silv. Res. Conf. Shreveport, LA, February 16-18, 1999. Pp. 232-237 Abstract - Coarse woody debris (CWD) is an important structural component of southern forest ecosystems. CWD loading may be affected by different decomposition rates on sites of varying quality. Bolts of red oak and loblolly pine were placed on plots at each of three (hydric, mesic. and xerlc) sites at the Savannah River Site and sampled over a I6-week period. Major changes were in moisture content and nonstructural carbohydrate content (total carbohydrates, reducing sugars, and starch) of sapwood. Early changes in nonstructural carbohydrate levels following placement of the bolts were likely due to reallocation of these materials by sapwood parenchyma cells. These carbohydrates later formed pools increasingly metabolized by bacteria and invading fungi. Most prevalent fungi in sapwood were Ceratocysfis spp. in pine and Hypoxy/on spp. in oak. Although pine sapwood became blue stained and oak sapwood exhibited yellow soft decay with black zone lines, estimators of decay (specific gravity, sodium hydroxide solubility, and holocellulose content) were unchanged during the 16-week study period. A small effect of site was detected for starch content of sapwood of both species. Fungal biomass in sapwood of both species, as measured by ergosterol content, was detectable at week zero, increased somewhat by week three and increased significantly by week 16.

  14. Woody biomass phytoremediation of contaminated brownfield land.

    Science.gov (United States)

    French, Christopher J; Dickinson, Nicholas M; Putwain, Philip D

    2006-06-01

    Economic and environmental regeneration of post-industrial landscapes frequently involves some element of re-afforestation or tree planting. We report field trials that evaluate whether woody biomass production is compatible with managing residual trace element contamination in brownfield soils. Large-scale mapping of contamination showed a heterogenous dispersion of metals and arsenic, and highly localised within-site hotspots. Yields of Salix, Populus and Alnus were economically viable, showing that short-rotation coppice has a potentially valuable role in community forestry. Mass balance modelling demonstrated that phytoextraction potentially could reduce contamination hotspots of more mobile elements (Cd and Zn) within a 25-30-year life cycle of the crops. Cd and Zn in stems and foliage of Salix were 4-13 times higher than EDTA-extractable soil concentrations. Lability of other trace elements (As, Pb, Cu, Ni) was not increased 3 years after planting the coppice; woody biomass may provide an effective reduction of exposure (phyto-stabilization) to these less mobile contaminants.

  15. A preliminary report on the dynamics of the vegetation of the Kalahari Gemsbok National Park

    Directory of Open Access Journals (Sweden)

    N van Rooyen

    1984-12-01

    Full Text Available Different methods were used intermittently to monitor the changes in the floristic composition, basal cover and density of the herbaceous and woody vegetation over a seven year period in the Kalahari Gemsbok National Park. Periods of drought and the variability of rainfall appear to have a significant influence in the short term on herbaceous species, while there was not much variation in the woody species composition or density.

  16. Variation in stem mortality rates determines patterns of above-ground biomass in Amazonian forests: implications for dynamic global vegetation models

    NARCIS (Netherlands)

    Johnson, Michelle O.; Galbraith, David; Gloor, Manuel; Deurwaerder, De Hannes; Guimberteau, Matthieu; Rammig, Anja; Thonicke, Kirsten; Verbeeck, Hans; Randow, Von Celso; Monteagudo, Abel; Phillips, Oliver L.; Brienen, Roel J.W.; Feldpausch, Ted R.; Lopez Gonzalez, Gabriela; Fauset, Sophie; Quesada, Carlos A.; Christoffersen, Bradley; Ciais, Philippe; Sampaio, Gilvan; Kruijt, Bart; Meir, Patrick; Moorcroft, Paul; Zhang, Ke; Alvarez-Davila, Esteban; Alves De Oliveira, Atila; Amaral, Ieda; Andrade, Ana; Aragao, Luiz E.O.C.; Araujo-Murakami, Alejandro; Arets, Eric J.M.M.; Arroyo, Luzmila; Aymard, Gerardo A.; Baraloto, Christopher; Barroso, Jocely; Bonal, Damien; Boot, Rene; Camargo, Jose; Chave, Jerome; Cogollo, Alvaro; Cornejo Valverde, Fernando; Lola Da Costa, Antonio C.; Fiore, Di Anthony; Ferreira, Leandro; Higuchi, Niro; Honorio, Euridice N.; Killeen, Tim J.; Laurance, Susan G.; Laurance, William F.; Licona, Juan; Lovejoy, Thomas; Malhi, Yadvinder; Marimon, Bia; Marimon, Ben Hur; Matos, Darley C.L.; Mendoza, Casimiro; Neill, David A.; Pardo, Guido; Peña-Claros, Marielos; Pitman, Nigel C.A.; Poorter, Lourens; Prieto, Adriana; Ramirez-Angulo, Hirma; Roopsind, Anand; Rudas, Agustin; Salomao, Rafael P.; Silveira, Marcos; Stropp, Juliana; Steege, Ter Hans; Terborgh, John; Thomas, Raquel; Toledo, Marisol; Torres-Lezama, Armando; Heijden, van der Geertje M.F.; Vasquez, Rodolfo; Guimarães Vieira, Ima Cèlia; Vilanova, Emilio; Vos, Vincent A.; Baker, Timothy R.

    2016-01-01

    Understanding the processes that determine aboveground biomass (AGB) in Amazonian forests is important for predicting the sensitivity of these ecosystems to environmental change and for designing and evaluating dynamic global vegetation models (DGVMs). AGB is determined by inputs from woody

  17. Quantifying Sub-Pixel Surface Water Coverage in Urban Environments Using Low-Albedo Fraction from Landsat Imagery

    Directory of Open Access Journals (Sweden)

    Weiwei Sun

    2017-05-01

    Full Text Available The problem of mixed pixels negatively affects the delineation of accurate surface water in Landsat Imagery. Linear spectral unmixing has been demonstrated to be a powerful technique for extracting surface materials at a sub-pixel scale. Therefore, in this paper, we propose an innovative low albedo fraction (LAF method based on the idea of unconstrained linear spectral unmixing. The LAF stands on the “High Albedo-Low Albedo-Vegetation” model of spectral unmixing analysis in urban environments, and investigates the urban surface water extraction problem with the low albedo fraction map. Three experiments are carefully designed using Landsat TM/ETM+ images on the three metropolises of Wuhan, Shanghai, and Guangzhou in China, and per-pixel and sub-pixel accuracies are estimated. The results are compared against extraction accuracies from three popular water extraction methods including the normalized difference water index (NDWI, modified normalized difference water index (MNDWI, and automated water extraction index (AWEI. Experimental results show that LAF achieves a better accuracy when extracting urban surface water than both MNDWI and AWEI do, especially in boundary mixed pixels. Moreover, the LAF has the smallest threshold variations among the three methods, and the fraction threshold of 1 is a proper choice for LAF to obtain good extraction results. Therefore, the LAF is a promising approach for extracting urban surface water coverage.

  18. Changes in woody species composition following establishing ...

    African Journals Online (AJOL)

    Restoring vegetation in low rainfall areas is difficult and urges the need to design an effective and low-cost method of vegetation restoration. This study was undertaken in the lowlands of northern Ethiopia to: (1) investigate how exclosure age affects restoration of degraded native plant species richness, diversity and ...

  19. A reconnaissance survey of the vegetation of the North Luangwa National Park, Zambia

    Directory of Open Access Journals (Sweden)

    P. P. Smith

    1998-12-01

    Full Text Available A comprehensive survey of the vegetation of the North Luangwa National Park (NLNP was carried out over a period of two years. The main aims of the survey were to describe the major vegetation communities in the park and to produce a vegetation map of the NLNP Initial differentiation of vegetation units was established by the appearance of the vegetation on aerial photographs Further information was derived from 353 ground plots in which > 20 000 woody plants were identified and measured Thirteen broad vegetation types were recognised in the NLNP Details of their physiognomy, species composition, distribution, topography and edaphic associations are given.  

  20. Vegetation impoverishment despite greening: a case study from central Senegal

    Science.gov (United States)

    Herrmann, Stefanie M.; Tappan, G. Gray

    2013-01-01

    Recent remote sensing studies have documented a greening trend in the semi-arid Sahel and Sudan zones of West Africa since the early 1980s, which challenges the mainstream paradigm of irreversible land degradation in this region. What the greening trend means on the ground, however, has not yet been explored. This research focuses on a region in central Senegal to examine changes in woody vegetation abundance and composition in selected sites by means of a botanical inventory of woody vegetation species, repeat photography, and perceptions of local land users. Despite the greening, an impoverishment of the woody vegetation cover was observed in the studied sites, indicated by an overall reduction in woody species richness, a loss of large trees, an increasing dominance of shrubs, and a shift towards more arid-tolerant, Sahelian species since 1983. Thus, interpretation of the satellite-derived greening trend as an improvement or recovery is not always justified. The case of central Senegal represents only one of several possible pathways of greening throughout the region, all of which result in similar satellite-derived greening signals.

  1. Influence of ozone on selected woody ornamentals

    Energy Technology Data Exchange (ETDEWEB)

    Wood, F.A.; Coppolino, J.B.

    1971-01-01

    Approximately 900 plants of 24 woody ornamental species were exposed to 25 pphm ozone for 8 hr at 24 C, 75% relative humidity, and 1400 ft-c of light. Cercis canadensis, Cotoneaster divaricata, C. horizontalis, Forsythia intermedia spectabilis Lynwood Gold, Gleditsia triacanthos inermis, Rhododendron kaempheri Camp fire, R. kurume Snow, R. catawbiense album, R. nova zembla, R. roseium elegans, Sorbus aucuparia, Syringa vulgaris, and Viburnum carlesi were sensitive. The most common symptoms were brown to black necrotic stipples on the upper leaf surface and premature defoliation. Interveinal necrotic and chlorotic flecks occurred infrequently. Current leaves of intermediate age were most sensitive. Euonymous alatus compacta, Hedra helix, Juniperus communis depressa plumosa, Pachysandra terminalis, Pieris japonica, Pyracantha coccinea lalandi, Rhododendron caroliniana, R. mollis, Taxus cuspidata, T. media hicksi, and Vinca minor were resistant.

  2. Absorption of some mineral salts by root system of different woody species and accumulation over a whole vegetative cycle (1963); Absorption de quelques sels par l'appareil radiculaire de differentes especes ligneuses et accumulation au cours d'un cycle vegetatif complet (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Gagnaire, J.; Gerard, J.M. [Commisariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-07-01

    The concentration power of plant tissues and the translocation speed of mineral salts are considerably varying with the absorbed salt, the botanical species, the considered tissue and the part of the vegetative cycle. In Grenoble, with Picea excelsa, the 'true dormancy' is short (half-november, end of december). It is accompanied by a pre-dormancy period (October, half-november) and a post dormancy period (January, february, march). In vegetative period, Picea excelsa leaves are less concentrating mineral salt than Acer campestris leaves (coefficient 2 for calcium - 3 for phosphates) and Populus nigra leaves (coefficient 3 for calcium, coefficient 5 for phosphates). (author) [French] Le pouvoir de concentration de tissus vegetaux, et particulierement la vitesse de transport des sels mineraux varient beaucoup selon le sel mineral absorbe, l'espece vegetale, le tissu considere ainsi que la periode du cycle vegetatif. A Grenoble, pour les epiceas 'la dormance veritable' est courte (mi-novembre, fin decembre). Elle est encadree par des periodes de pre-dormance (octobre, mi-novembre) et de post-dormance (janvier, fevrier, mars). Pendant la periode vegetative, le pouvoir de concentration de sels mineraux des aiguilles d'epiceas est plus faible que celui des feuilles d'erables (coefficient 2 pour le calcium - coefficient 3 pour les phosphates) ou que celui des feuilles de peupliers (coefficient 3 pour le calcium - coefficient 5 pour les phosphates). (auteur)

  3. Correction of sub-pixel topographical effects on land surface albedo retrieved from geostationary satellite (FengYun-2D) observations

    NARCIS (Netherlands)

    Roupioz, L.F.S.; Jia, L.; Nerry, F.; Menenti, M.

    2014-01-01

    The Qinghai-Tibetan Plateau is characterised by a very strong relief which affects albedo retrieval from satellite data. The objective of this study is to highlight the effects of subpixel topography and to account for those effects when retrieving land surface albedo from geostationary satellite

  4. The influence of coarse woody debris in the development of hydromorphic complexity within recently deglaciated streams

    Science.gov (United States)

    Klaar, M. J.; Hill, D. F.; Maddock, I.; Milner, A. M.

    2009-12-01

    The natural accumulation of logs, branches and other woody vegetation into the stream environment (coarse woody debris (CWD) accumulations) from adjacent stream banks plays an important role in altering the physical and ecological behaviour of rivers. CWD is often used as a tool in restoration projects to create or enhance instream habitat for biota. Research focussing on the influence of CWD characteristics on the three-dimensional flow structure surrounding accumulations, and quantification of the resultant changes in hydraulic and geomorphic composition is generally lacking. Rapid glacial recession within Glacier Bay National Park, Alaska has created the unique opportunity to study the development of a number of watersheds representing 200 years of development and varying degrees of CWD recruitment. Watershed age is related to its distance from the glacier termini, and thus temporal changes in habitat development can be studied on the basis of spatial differences. Size, position and dam properties of debris structures were mapped in order to monitor the long-term movement and formation of debris dams and associated geomorphic and ecological response. The influence of CWD characteristics on the development of geomorphic diversity and hydraulic variability were assessed using detailed habitat mapping and hydraulic assessment using an Acoustic Doppler Current Profiler at a number of transects upstream, downstream and adjacent to woody debris structures. Debris characteristics were found to alter across the watersheds as a result of adjacent terrestrial floodplain development and the subsequent introduction of woody debris into the riverine environment as a result of bank erosion. Results showed that riparian vegetation must be of a sufficient stage of development to elicit significant change in the geomorphic and hydraulic composition of the stream. Increased habitat heterogeneity within older watersheds was linked to the presence of complex debris structures

  5. Woody biomass for bioenergy and biofuels in the United States -- a briefing paper

    Science.gov (United States)

    Eric M. White

    2010-01-01

    Woody biomass can be used for the generation of heat, electricity, and biofuels. In many cases, the technology for converting woody biomass into energy has been established for decades, but because the price of woody biomass energy has not been competitive with traditional fossil fuels, bioenergy production from woody biomass has not been widely adopted. However,...

  6. Pretreatment of woody biomass for biofuel production: energy efficiency, technologies, and recalcitrance

    Science.gov (United States)

    J.Y. Zhu; Xuejun Pan; Ronald S. Jr. Zalesny

    2010-01-01

    This mini review discusses several key technical issues associated with cellulosic ethanol production from woody biomass: energy consumption for woody biomass pretreatment, pretreatment energy efficiency, woody biomass pretreatment technologies, and quantification of woody biomass recalcitrance. Both total sugar yield and pretreatment energy efficiency, defined as the...

  7. Impacts of deer herbivory on vegetation in Rock Creek Park, 2001-2009

    Science.gov (United States)

    Kraft, Cairn C.; Hatfield, Jeff S.

    2011-01-01

    Starting in 2001, vegetation data have been collected annually in 16 study modules consisting of paired (1x4 m) fenced plots and unfenced control plots located in the upland forests of Rock Creek Park, Washington, D.C. Vegetation data collected from 2001-2009 have been analyzed to determine impacts of deer herbivory on vegetation in the park. Differences between fenced plots and unfenced control plots were analyzed for the following variables: cover provided by various groups of species (woody, herbaceous, native, non-native, trees, shrubs, and woody vines), as well as by individual dominant species, vegetation thickness (a measure of percent cover projected horizontally that provides information on the vertical distribution of vegetation), and species richness overall and for groups of species (woody, herbaceous, native, non-native, trees, shrubs, and woody vines). The analyses were performed using repeated measures analysis of variance (ANOVA) and associated tests. Vegetation in plots protected from deer herbivory for 9 years showed significantly greater vegetative cover compared to plots not protected from deer herbivory. This effect was most pronounced for woody and shrub cover. Cover by the dominant species was not significantly greater in the fenced plots compared to the unfenced control plots, indicating that the significant differences observed for groups were not driven by single species within those groups. With respect to vegetation thickness, results indicate that protection from deer herbivory produced significantly higher levels of vegetation in the fenced plots compared to the unfenced control plots for both the Low (0-30 cm) and Middle (30-110 cm) height classes. Protection from deer herbivory has led to higher overall species richness and higher species richness for woody species, natives, and shrubs compared to plots not receiving protection. There is also evidence that plots protected from deer herbivory and those not receiving this protection

  8. How to deal with radiologically contaminated vegetation

    Energy Technology Data Exchange (ETDEWEB)

    Wilde, E.W.; Murphy, C.E.; Lamar, R.T.; Larson, M.J.

    1996-12-31

    This report describes the findings from a literature review conducted as part of a Department of Energy, Office of Technology Development Biomass Remediation Task. The principal objective of this project is to develop a process or group of processes to treat radiologically contaminated vegetation in a manner that minimizes handling, processing, and treatment costs. Contaminated, woody vegetation growing on waste sites at SRS poses a problem to waste site closure technologies that are being considered for these sites. It is feared that large sections of woody vegetation (logs) can not be buried in waste sites where isolation of waste is accomplished by capping the site. Logs or large piles of woody debris have the potential of decaying and leaving voids under the cap. This could lead to cap failure and entrance of water into the waste. Large solid objects could also interfere with treatments like in situ mixing of soil with grout or other materials to encapsulate the contaminated sediments and soils in the waste sites. Optimal disposal of the wood includes considerations of volume reduction, treatment of the radioactive residue resulting from volume reduction, or confinement without volume reduction. Volume reduction consists primarily of removing the carbon, oxygen, and hydrogen in the wood, leaving an ash that would contain most of the contamination. The only contaminant that would be released by volume reduction would by small amounts of the radioactive isotope of hydrogen, tritium. The following sections will describe the waste sites at SRS which contain contaminated vegetation and are potential candidates for the technology developed under this proposal. The description will provide a context for the magnitude of the problem and the logistics of the alternative solutions that are evaluated later in the review. 76 refs.

  9. Color capable sub-pixel resolving optofluidic microscope and its application to blood cell imaging for malaria diagnosis.

    Directory of Open Access Journals (Sweden)

    Seung Ah Lee

    Full Text Available Miniaturization of imaging systems can significantly benefit clinical diagnosis in challenging environments, where access to physicians and good equipment can be limited. Sub-pixel resolving optofluidic microscope (SROFM offers high-resolution imaging in the form of an on-chip device, with the combination of microfluidics and inexpensive CMOS image sensors. In this work, we report on the implementation of color SROFM prototypes with a demonstrated optical resolution of 0.66 µm at their highest acuity. We applied the prototypes to perform color imaging of red blood cells (RBCs infected with Plasmodium falciparum, a particularly harmful type of malaria parasites and one of the major causes of death in the developing world.

  10. Estimation of sub-pixel water area on Tibet plateau using multiple endmembers spectral mixture spectral analysis from MODIS data

    Science.gov (United States)

    Cui, Qian; Shi, Jiancheng; Xu, Yuanliu

    2011-12-01

    Water is the basic needs for human society, and the determining factor of stability of ecosystem as well. There are lots of lakes on Tibet Plateau, which will lead to flood and mudslide when the water expands sharply. At present, water area is extracted from TM or SPOT data for their high spatial resolution; however, their temporal resolution is insufficient. MODIS data have high temporal resolution and broad coverage. So it is valuable resource for detecting the change of water area. Because of its low spatial resolution, mixed-pixels are common. In this paper, four spectral libraries are built using MOD09A1 product, based on that, water body is extracted in sub-pixels utilizing Multiple Endmembers Spectral Mixture Analysis (MESMA) using MODIS daily reflectance data MOD09GA. The unmixed result is comparing with contemporaneous TM data and it is proved that this method has high accuracy.

  11. Subpixel Inundation Mapping Using Landsat-8 OLI and UAV Data for a Wetland Region on the Zoige Plateau, China

    Directory of Open Access Journals (Sweden)

    Haoming Xia

    2017-01-01

    Full Text Available Wetland inundation is crucial to the survival and prosperity of fauna and flora communities in wetland ecosystems. Even small changes in surface inundation may result in a substantial impact on the wetland ecosystem characteristics and function. This study presented a novel method for wetland inundation mapping at a subpixel scale in a typical wetland region on the Zoige Plateau, northeast Tibetan Plateau, China, by combining use of an unmanned aerial vehicle (UAV and Landsat-8 Operational Land Imager (OLI data. A reference subpixel inundation percentage (SIP map at a Landsat-8 OLI 30 m pixel scale was first generated using high resolution UAV data (0.16 m. The reference SIP map and Landsat-8 OLI imagery were then used to develop SIP estimation models using three different retrieval methods (Linear spectral unmixing (LSU, Artificial neural networks (ANN, and Regression tree (RT. Based on observations from 2014, the estimation results indicated that the estimation model developed with RT method could provide the best fitting results for the mapping wetland SIP (R2 = 0.933, RMSE = 8.73% compared to the other two methods. The proposed model with RT method was validated with observations from 2013, and the estimated SIP was highly correlated with the reference SIP, with an R2 of 0.986 and an RMSE of 9.84%. This study highlighted the value of high resolution UAV data and globally and freely available Landsat data in combination with the developed approach for monitoring finely gradual inundation change patterns in wetland ecosystems.

  12. Post-wildfire recovery of riparian vegetation during a period of water scarcity in the southwestern USA

    Science.gov (United States)

    D. Max Smith; Deborah M. Finch; Christian Gunning; Roy Jemison; Jeffrey F. Kelly

    2009-01-01

    Wildland fires occur with increasing frequency in southwestern riparian forests, yet little is known about the effects of fire on populations of native and exotic vegetation. From 2003 to 2006, we monitored recovering woody vegetation in wildfire sites in the bosque (riparian forest) along the Middle Rio Grande of central New Mexico, USA. To examine recovery potential...

  13. Vegetation Change, Tree Diversity and Food Security in the Sahel

    DEFF Research Database (Denmark)

    Sambou, Antoine

    was found in forest than other landscape elements. In contrast, tree richness was higher in croplands in Boly Serere and Poukham Tock. Factors such as land-use, soil salinity and pH had significant effects on vegetation parameters. Local people had observed a general decline of woody plants....... This was confirmed by satellite imagery analysis. Satellite images showed losses tree cover and mangrove, and an increase in shrub and herbaceous covers and tans. Human activities and environmental factors (especially salinization) appear to be the main drivers of vegetation change. Overall, the vegetation change...

  14. Presettlement Vegetation

    Data.gov (United States)

    Minnesota Department of Natural Resources — Presettlement vegetation of Minnesota based on Marschner's original analysis of Public Land Survey notes and landscape patterns. Marschner compiled his results in...

  15. Process integration to increase woody biomass utilization for energy purposes

    OpenAIRE

    Mesfun, Sennai

    2016-01-01

    Woody biomass is an abundant renewable energy resource in Sweden, and the Swedish government has been promoting research and development programs for the exploitation of this resource as a mean to meet the targets on the reduction of the carbon dioxide emissions from the industrial, energy and transportation sectors. This thesis aims at expanding the knowledge on the efficient utilization of the available woody biomass, so that a larger amount of this renewable resource can be used for energy...

  16. Distributed Modeling Reveals the Ecohydrological Dynamics Linked with Woody Plant Encroachment in the Sonoran Desert

    Science.gov (United States)

    Pierini, N. A.; Vivoni, E. R.; Anderson, C.; Saripalli, S.; Robles-Morua, A.

    2012-12-01

    Woody plant encroachment is an important issue facing semiarid ecosystems in the southwestern United States that is associated with grazing pressures, fire suppression, and the invasion of shrub species into historical grasslands. In this study, we present observational and distributed modeling activities conducted in two small rangeland watersheds of the Santa Rita Experimental Range, Arizona. This Sonoran Desert landscape is representative of the vegetation shift from grasslands to a woody savanna due to the encroachment of velvet mesquite (Prosopis velutina). The paired basins are similar in size and in close proximity, leading to equivalent meteorological and soil conditions. Nevertheless, they vary substantially in mesquite cover, with one basin having undergone a removal treatment several decades ago, while the other watershed represents the regional encroachment process. This distinction presents an excellent case study for analyzing the effects of mesquite encroachment on dryland ecohydrological dynamics. Observational datasets are obtained from a high-resolution environmental sensor network consisting of six rain gauges, twenty-one soil moisture and temperature profiles, five channel runoff flumes and an eddy covariance tower with a complete set of radiation, energy, carbon and water fluxes. In addition, high-resolution digital terrain models and image orthomosaics were obtained from a piloted aircraft with Light Detection and Ranging (LiDAR) measurements and an Unmanned Aerial Vehicle (UAV) with a digital camera. These two remote sensing platforms allowed characterizing the topography, stream network and plant species distributions at a high resolution (designed to reveal the influence of the mesquite encroachment patterns on the watershed dynamics. Through the spatiotemporal analysis of model outputs, we identify how and when mesquite trees affect the spatial patterns of energy and water fluxes and their linkage to runoff production. As a result, the

  17. Aluminum exclusion and aluminum tolerance in woody plants.

    Science.gov (United States)

    Brunner, Ivano; Sperisen, Christoph

    2013-01-01

    The aluminum (Al) cation Al(3) (+) is highly rhizotoxic and is a major stress factor to plants on acid soils, which cover large areas of tropical and boreal regions. Many woody plant species are native to acid soils and are well adapted to high Al(3) (+) conditions. In tropical regions, both woody Al accumulator and non-Al accumulator plants occur, whereas in boreal regions woody plants are non-Al accumulators. The mechanisms of these adaptations can be divided into those that facilitate the exclusion of Al(3) (+) from root cells (exclusion mechanisms) and those that enable plants to tolerate Al(3) (+) once it has entered the root and shoot symplast (internal tolerance mechanisms). The biochemical and molecular basis of these mechanisms have been intensively studied in several crop plants and the model plant Arabidopsis. In this review, we examine the current understanding of Al(3) (+) exclusion and tolerance mechanisms from woody plants. In addition, we discuss the ecology of woody non-Al accumulator and Al accumulator plants, and present examples of Al(3) (+) adaptations in woody plant populations. This paper complements previous reviews focusing on crop plants and provides insights into evolutionary processes operating in plant communities that are widespread on acid soils.

  18. Aluminium exclusion and aluminium tolerance in woody plants

    Directory of Open Access Journals (Sweden)

    Ivano eBrunner

    2013-06-01

    Full Text Available The aluminium (Al cation Al3+ is highly rhizotoxic and is a major stress factor to plants on acid soils, which cover large areas of tropical and boreal regions. Many woody plant species are native to acid soils and are well adapted to high Al3+ conditions. In tropical regions, both woody Al accumulator and non-Al accumulator plants occur, whereas in boreal regions woody plants are non-Al accumulators. The mechanisms of these adaptations can be divided into those that facilitate the exclusion of Al3+ from root cells (exclusion mechanisms and those that enable plants to tolerate Al3+ once it has entered the root and shoot symplast (internal tolerance mechanisms. The biochemical and molecular basis of these mechanisms have been intensively studied in several crop plants and the model plant Arabidopsis. In this review, we examine the current understanding of Al3+ exclusion and tolerance mechanisms from woody plants. In addition, we discuss the ecology of woody non-Al accumulator and Al accumulator plants, and present examples of Al3+ adaptations in woody plant populations. This paper complements previous reviews focusing on crop plants and provides insights into evolutionary processes operating in plant communities that are widespread on acid soils.

  19. Acetylation of woody lignocellulose: significance and regulation

    Directory of Open Access Journals (Sweden)

    Prashant Mohan-Anupama Pawar

    2013-05-01

    Full Text Available Non-cellulosic cell wall polysaccharides constitute approximately one quarter of usable biomass for human exploitation. In contrast to cellulose, these components are usually substituted by O-acetyl groups, which affect their properties and interactions with other polymers, thus affecting their solubility and extractability. However, details of these interactions are still largely obscure. Moreover, polysaccharide hydrolysis to constituent monosaccharides, is hampered by the presence of O-acetyl groups, necessitating either enzymatic (esterase or chemical de-acetylation, increasing the costs and chemical consumption. Reduction of polysaccharide acetyl content in planta is a way to modify lignocellulose towards improved saccharification. In this review we: 1 summarize literature on lignocellulose acetylation in different tree species, 2 present data and current hypotheses concerning the role of O-acetylation in determining woody lignocellulose properties, 3 describe plant proteins involved in lignocellulose O-acetylation, 4 give examples of microbial enzymes capable to de-acetylate lignocellulose, and 5 discuss prospects for exploiting these enzymes in planta to modify xylan acetylation.

  20. Extreme low temperature tolerance in woody plants

    Directory of Open Access Journals (Sweden)

    George Richard Strimbeck

    2015-10-01

    Full Text Available Woody plants in boreal to arctic environments and high mountains survive prolonged exposure to temperatures below -40˚C and minimum temperatures below -60˚C, and laboratory tests show that many of these species can also survive immersion in liquid nitrogen at -196˚C. Studies of biochemical changes that occur during acclimation, including recent proteomic and metabolomic studies, have identified changes in carbohydrate and compatible solute concentrations, membrane lipid composition, and proteins, notably dehydrins, that may have important roles in survival at extreme low temperature. Consideration of the biophysical mechanisms of membrane stress and strain lead to the following hypotheses for cellular and molecular mechanisms of survival at extreme low temperature: 1. Changes in lipid composition stabilize membranes at temperatures above the lipid phase transition temperature (-20 to 30˚C, preventing phase changes that result in irreversible injury. 2. High concentrations of oligosaccharides promote vitrification or high viscosity in the cytoplasm in freeze-dehydrated cells, which would prevent deleterious interactions between membranes. 3. Dehydrins bind membranes and further promote vitrification or act stearically to prevent membrane-membrane interactions.

  1. Woody plant encroachment reduces annual runoff and shifts runoff mechanisms in the tallgrass prairie, USA

    Science.gov (United States)

    Qiao, Lei; Zou, Chris B.; Stebler, Elaine; Will, Rodney E.

    2017-06-01

    Woody plant encroachment into semiarid and subhumid rangelands is a global phenomenon with important hydrological implications. Observational and experimental results reported both increases and decreases in annual runoff for encroached watersheds and little is known regarding the underlying runoff generation mechanisms. To systematically study the effect of woody plant encroachment on runoff generation processes, seven experimental watersheds were instrumented in 2010, three on grassland sites and four on adjacent sites that were heavily encroached by eastern redcedar (Juniperus virginiana) in the southern Great Plains, USA. Results showed that the runoff coefficient was 1.4 ± 0.6% in eastern redcedar encroached watersheds, significantly lower than 4.4 ± 0.7% in grassland watersheds for the four water years from 2011 to 2014. Eastern redcedar encroachment resulted in reduction of both surface and subsurface flows and the magnitude of reduction depended on annual precipitation. While there were nearly equal contributions between overland flow and subsurface flow, 87% of the total runoff from grassland watersheds occurred under saturated or nearly saturated soil condition, while 86% of runoff under encroached watersheds was generated under unsaturated soil condition, suggesting a shift from saturation excess overland flow to infiltration excess overland flow. These results permitted reconciliation of observed difference of streamflow responses associated with Juniperus spp. encroachment in the region and provided insights to better predict change in water resources under vegetation changes in subhumid regions of the south-central USA.

  2. Useful woody species and its environmental availability: the case of artisanal fishermen in Itaúnas, Brazil

    Directory of Open Access Journals (Sweden)

    Lucas Costa Monteiro Lopes

    2017-06-01

    Full Text Available Ethnobotanical studies involve research with human societies and their different interaction with plants, and the quantitative approaches from thes estudies are important to select conservation priority of species in natural environment. This research aims to quantify use-values for woody plants mentioned by fishers in Itaúnas, state of Espírito Santo, and evaluate the relationship between use-values and species availability (absolute density and frequency, and importance value in two distinct resting vegetation formations. It also proposes to identify priority species for conservation. It was selected 30 species cited in individual semi-structured interviews with key-informant in fishers’ community and who were also on list of structural survey of two vegetation phytophysiognomies in the restinga regions. The data used was collected in previously published work. It was performed a correlation analysis between use-values and structural parameters of the mentioned woody species. Protium heptaphyllum, P. icicariba and Byrsonima sericea present the highest use-values. It was not observed relation between use-value and species availability in each vegetation formation. It was classified two and eight species as priority for conservation on shrubby and forest formations, respectively.

  3. Technical Note: Linking climate change and downed woody debris decomposition across forests of the eastern United States

    Science.gov (United States)

    Russell, Matthew B.; Woodall, Christopher W.; D'Amato, Anthony W.; Fraver, Shawn; Bradford, John B.

    2014-01-01

    Forest ecosystems play a critical role in mitigating greenhouse gas emissions. Forest carbon (C) is stored through photosynthesis and released via decomposition and combustion. Relative to C fixation in biomass, much less is known about C depletion through decomposition of woody debris, particularly under a changing climate. It is assumed that the increased temperatures and longer growing seasons associated with projected climate change will increase the decomposition rates (i.e., more rapid C cycling) of downed woody debris (DWD); however, the magnitude of this increase has not been previously addressed. Using DWD measurements collected from a national forest inventory of the eastern United States, we show that the residence time of DWD may decrease (i.e., more rapid decomposition) by as much as 13% over the next 200 years, depending on various future climate change scenarios and forest types. Although existing dynamic global vegetation models account for the decomposition process, they typically do not include the effect of a changing climate on DWD decomposition rates. We expect that an increased understanding of decomposition rates, as presented in this current work, will be needed to adequately quantify the fate of woody detritus in future forests. Furthermore, we hope these results will lead to improved models that incorporate climate change scenarios for depicting future dead wood dynamics in addition to a traditional emphasis on live-tree demographics.

  4. Biodiversity of Soil Microbial Communities Following Woody Plant Invasion of Grassland: An Assessment Using Molecular Methods

    Science.gov (United States)

    Kantola, I. B.; Gentry, T. J.; Filley, T. R.; Boutton, T. W.

    2012-12-01

    Woody plants have encroached into grasslands, savannas, and other grass-dominated ecosystems throughout the world during the last century. This dramatic vegetation change is likely driven by livestock grazing, altered fire frequencies, elevated atmospheric CO2 concentrations, and/or changes in atmospheric deposition patterns. Woody invasion often results in significant changes in ecosystem function, including alterations in above- and belowground primary productivity, soil C, N, and P storage and turnover, and the size and activity of the soil microbial biomass pool. The purpose of this study was to examine the relationships and interactions between plant communities and soil microbial communities in the Rio Grande Plains region of southern Texas where grasslands have been largely replaced by woodlands. Research was conducted along a successional chronosequence representing the stages of woody plant encroachment from open grassland to closed-canopy woodland. To characterize soil microbial community composition, soil samples (0-7.5 cm) were collected in remnant grasslands (representing time 0) and near the centers of woody plant clusters, groves, and drainage woodlands ranging in age from 10 to 130 yrs. Ages of woody plant stands were determined by dendrochronology. Community DNA was extracted from each soil sample with a MoBio PowerMax Soil DNA isolation kit. The DNA concentrations were quantified on a NanoDrop ND-1000 spectrophotometer and diluted to a standard concentration. Pyrosequencing was performed by the Research and Testing Laboratory (Lubbock, TX) according to Roche 454 Titanium chemistry protocols. Samples were amplified with primers 27F and 519R for bacteria, and primers ITS1F and ITS4 for fungi. Sequences were aligned using BioEdit and the RDP Pipeline and analyzed in MOTHUR. Non-metric multidimensional scaling of the operational taxonomic units identified by pyrosequencing revealed that both bacterial and fungal community composition were

  5. Kuchler Vegetation

    Data.gov (United States)

    California Department of Resources — Digital version of potential natural plant communites as compiled and published on 'Map of the Natural Vegetation of California' by A. W. Kuchler, 1976. Source map...

  6. Wieslander Vegetation

    Data.gov (United States)

    California Department of Resources — Digital version of the 1945 California Vegetation Type Maps by A. E. Wieslander of the U.S. Forest Service. Source scale of maps are 1:100,000. These compiled maps...

  7. [Progress on whole genome sequencing in woody plants].

    Science.gov (United States)

    Shi, Ji-Sen; Wang, Zhan-Jun; Chen, Jin-Hui

    2012-02-01

    In recent years, the number of sequencing data of plant whole genome have been increasing rapidly and the whole genome sequencing has been also performed widely in woody plants. However, there are a set of obstacles in investigating the whole genome sequencing in woody plants, which include larger genome, complex genome structure, limitations of assembly, annotation, functional analysis, and restriction of the funds for scientific research. Therefore, to promote the efficiency of the whole genome sequencing in woody plants, the development and defect of this field should be analyzed. The three-generation sequencing technologies (i.e., Sanger sequencing, synthesis sequencing, and single molecule sequencing) were compared in our studies. The progress mainly focused on the whole genome sequencing in four woody plants (Populus, Grapevine, Papaya, and Apple), and the application of sequencing results also was analyzed. The future of whole genome sequencing research in woody plants, consisting of material selection, establishment of genetic map and physical map, selection of sequencing technology, bioinformatic analysis, and application of sequencing results, was discussed.

  8. Effects of fire frequency and season on resprouting of woody plants in southeastern US pine-grassland communities.

    Science.gov (United States)

    Robertson, Kevin M; Hmielowski, Tracy L

    2014-03-01

    Past studies suggest that rates of woody plant resprouting following a "topkilling" disturbance relate to timing of disturbance because of temporal patterns of below-ground carbohydrate storage. Accordingly, we hypothesized that fire-return interval (1 or 2 years) and season of burn (late dormant or early growing season) would influence the change in resprout growth rate from one fire-free interval to the next (Δ growth rate) for broadleaf woody plants in a pine-grassland in Georgia, USA. Resprout growth rate during one fire-free interval strongly predicted growth rate during the following fire-free interval, presumably reflecting root biomass. Length of fire-free interval did not have a significant effect on mean Δ growth rate. Plants burned in the late dormant season (February-March) had a greater positive Δ growth rate than those burned in the early growing season (April-June), consistent with the presumption that root carbohydrates are depleted and thus limiting during spring growth. Plants with resprout growth rates above a certain level had zero or negative Δ growth rates, indicating an equilibrium of maximum resprout size under a given fire-return interval. This equilibrium, as well as relatively reduced resprout growth rate following growing season fires, provide insight into how historic lightning-initiated fires in the early growing season limited woody plant dominance and maintained the herb-dominated structure of pine-grassland communities. Results also indicate tradeoffs between applying prescribed fire at 1- versus 2-year intervals and in the dormant versus growing seasons with the goal of limiting woody vegetation.

  9. Boundary Shear Stress Along Vegetated Streambanks

    Science.gov (United States)

    Clark, L. A.; Wynn, T.

    2007-12-01

    Sediment, a leading cause of water quality impairment, damages aquatic ecosystems and interferes with recreational uses and water treatment processes. Streambank retreat can contribute as much as 85% of watershed sediment yield. Vegetation is an important component of stream restoration designs used to control streambank retreat, but vegetation effects on streambank boundary shear stress (SBSS) need to be quantified. The overall goal of this experiment is to predict boundary shear stress along vegetated streambanks. This goal will be met by determining a method for measuring boundary shear stress in the field along hydraulically rough streambanks, evaluating the effects of streambank vegetation on boundary shear stress in the field, and developing predictive methods based on measurable vegetative properties. First, three streambank vegetation types (herbaceous, shrubbery, and woody) will be modeled in a flume study to examine both boundary shear stress measurement theory and instruments for field use. An appropriate method (law of the wall, Reynold's stresses, TKE, or average wall shear stress) and field instrument (ADV, propeller, or Pitot tube) will be selected, resulting in a field technique to measure SBSS. Predictive methods for estimating SBSS, based on common vegetation measurements, will be developed in the flume study and validated with field data. This research is intended to improve our understanding of the role of riparian vegetation in stream morphology by evaluating the effects of vegetation on boundary shear stress, providing insight to the type and density of vegetation required for streambank stability. The results will also aide in quantifying sediment inputs from streambanks, providing quantitative information for stream restoration projects and watershed management planning.

  10. Woody Species Diversity in Traditional Agroforestry Practices of Dellomenna District, Southeastern Ethiopia: Implication for Maintaining Native Woody Species

    Directory of Open Access Journals (Sweden)

    Abiot Molla

    2015-01-01

    Full Text Available The major impact of humans on forest ecosystems including loss of forest area, habitat fragmentation, and soil degradation leads to losses of biodiversity. These problems can be addressed by integration of agriculture with forests and maintaining the existing forests. This study was initiated to assess woody species diversity of traditional agroforestry practices. Three study sites (Burkitu, Chire, and Erba were selected based on the presence of agroforestry practice. Forty-eight (48 sample quadrants having an area of 20 m × 20 m, 16 sample quadrants in each study site, were systematically laid using four transect lines at different distance. The diversity of woody species was analyzed by using different diversity indices. A total of 55 woody species belonging to 31 families were identified and documented. There were significantly different (P<0.05 among the study Kebeles (peasant associations. Mangifera indica, Entada abyssinica, and Croton macrostachyus were found to have the highest Important Value Index. The results confirmed that traditional agroforestry plays a major role in the conservation of native woody species. However, threats to woody species were observed. Therefore, there is a need to undertake conservation practices before the loss of species.

  11. Geographical patterns in the beta diversity of China's woody plants

    DEFF Research Database (Denmark)

    Wang, Zhiheng; Fang, Jingyun; Tang, Zhiyao

    2012-01-01

    .g. environmental niche versus dispersal limitation of species) remains elusive, and the influence of species range size has been poorly tested. Here, using distribution maps of 11 405 woody species in China (ca 9.6 ¿ 106 km2), we investigated 1) the geographical and directional patterns of beta diversity for all...... woody species and species with different range sizes, and 2) compared the effects of environmental and spatial processes on these patterns. Beta diversity was calculated as the decay of similarity in species composition with increasing distance. Variables representing environmental energy, water...... diversity of widely-ranged species. This was opposite to the larger influence of spatial processes on latitudinal beta diversity and the beta diversity of narrowly-ranged species. These results suggest that the distributions of narrowly-ranged woody species in China may have not reached equilibrium...

  12. The proteome of Populus nigra woody root: response to bending

    Science.gov (United States)

    Trupiano, Dalila; Rocco, Mariapina; Renzone, Giovanni; Scaloni, Andrea; Viscosi, Vincenzo; Chiatante, Donato; Scippa, Gabriella S.

    2012-01-01

    Background and Aims Morphological and biomechanical alterations occurring in woody roots of many plant species in response to mechanical stresses are well documented; however, little is known about the molecular mechanisms regulating these important alterations. The first forest tree genome to be decoded is that of Populus, thereby providing a tool with which to investigate the mechanisms controlling adaptation of woody roots to changing environments. The aim of this study was to use a proteomic approach to investigate the response of Populus nigra woody taproot to mechanical stress. Methods To simulate mechanical perturbations, the taproots of 30 one-year-old seedlings were bent to an angle of 90 ° using a steel net. A spatial and temporal two-dimensional proteome map of the taproot axis was obtained. We compared the events occurring in the above-bending, central bending and below-bending sectors of the taproot. Key Results The first poplar woody taproot proteome map is reported here; a total of 207 proteins were identified. Spatial and temporal proteomic analysis revealed that factors involved in plant defence, metabolism, reaction wood formation and lateral root development were differentially expressed in the various sectors of bent vs. control roots, seemingly in relation to the distribution of mechanical forces along the stressed woody taproots. A complex interplay among different signal transduction pathways involving reactive oxygen species appears to modulate these responses. Conclusions Poplar woody root uses different temporal and spatial mechanisms to respond to mechanical stress. Long-term bending treatment seem to reinforce the defence machinery, thereby enabling the taproot to better overcome winter and to be ready to resume growth earlier than controls. PMID:22437664

  13. Scrubbing Up: Multi-Scale Investigation of Woody Encroachment in a Southern African Savannah

    Directory of Open Access Journals (Sweden)

    Christopher G. Marston

    2017-04-01

    Full Text Available Changes in the extent of woody vegetation represent a major conservation question in many savannah systems around the globe. To address the problem of the current lack of broad-scale cost-effective tools for land cover monitoring in complex savannah environments, we use a multi-scale approach to quantifying vegetation change in Kruger National Park (KNP, South Africa. We test whether medium spatial resolution satellite data (Landsat, existing back to the 1970s, which have pixel sizes larger than typical vegetation patches, can nevertheless capture the thematic detail required to detect woody encroachment in savannahs. We quantify vegetation change over a 13-year period in KNP, examine the changes that have occurred, assess the drivers of these changes, and compare appropriate remote sensing data sources for monitoring change. We generate land cover maps for three areas of southern KNP using very high resolution (VHR and medium resolution satellite sensor imagery from February 2001 to 2014. Considerable land cover change has occurred, with large increases in shrubs replacing both trees and grassland. Examination of exclosure areas and potential environmental driver data suggests two mechanisms: elephant herbivory removing trees and at least one separate mechanism responsible for conversion of grassland to shrubs, theorised to be increasing atmospheric CO2. Thus, the combination of these mechanisms causes the novel two-directional shrub encroachment that we observe (tree loss and grassland conversion. Multi-scale comparison of classifications indicates that although spatial detail is lost when using medium resolution rather than VHR imagery for land cover classification (e.g., Landsat imagery cannot readily distinguish between tree and shrub classes, while VHR imagery can, the thematic detail contained within both VHR and medium resolution classifications is remarkably congruent. This suggests that medium resolution imagery contains sufficient

  14. Woody plant encroachment, and its removal, impact bacterial and fungal communities across stream and terrestrial habitats in a tallgrass prairie ecosystem.

    Science.gov (United States)

    Veach, Allison M; Dodds, Walter K; Jumpponen, Ari

    2015-10-01

    Woody plant encroachment has become a global threat to grasslands and has caused declines in aboveground richness and changes in ecosystem function; yet we have a limited understanding on the effects of these phenomena on belowground microbial communities. We completed riparian woody plant removals at Konza Prairie Biological Station, Kansas and collected soils spanning land-water interfaces in removal and woody vegetation impacted areas. We measured stream sediments and soils for edaphic variables (C and N pools, soil water content, pH) and bacterial (16S rRNA genes) and fungal (ITS2 rRNA gene repeat) communities using Illumina MiSeq metabarcoding. Bacterial richness and diversity decreased with distance from streams. Fungal richness decreased with distance from the stream in wooded areas, but was similar across landscape position while Planctomycetes and Basidiomycota relative abundance was lower in removal areas. Cyanobacteria, Ascomycota, Chytridiomycota and Glomeromycota relative abundance was greater in removal areas. Ordination analyses indicated that bacterial community composition shifted more across land-water interfaces than fungi yet both were marginally influenced by treatment. This study highlights the impacts of woody encroachment restoration on grassland bacterial and fungal communities which likely subsequently affects belowground processes and plant health in this ecosystem. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Detailed comparison of neuro-fuzzy estimation of subpixel land-cover composition from remotely sensed data

    Science.gov (United States)

    Baraldi, Andrea; Binaghi, Elisabetta; Blonda, Palma N.; Brivio, Pietro A.; Rampini, Anna

    1998-10-01

    Mixed pixels, which do not follow a known statistical distribution that could be parameterized, are a major source of inconvenience in classification of remote sensing images. This paper reports on an experimental study designed for the in-depth investigation of how and why two neuro-fuzzy classification schemes, whose properties are complementary, estimate sub-pixel land cover composition from remotely sensed data. The first classifier is based on the fuzzy multilayer perceptron proposed by Pal and Mitra: the second classifier consists of a two-stage hybrid (TSH) learning scheme whose unsupervised first stage is based on the fully self- organizing simplified adaptive resonance theory clustering network proposed by Baraldi. Results of the two neuro-fuzzy classifiers are assessed by means of specific evaluation tools designed to extend conventional descriptive and analytical statistical estimators to the case of multi-membership in classes. When a synthetic data set consisting of pure and mixed pixels is processed by the two neuro-fuzzy classifiers, experimental result show that: i) the two neuro- fuzzy classifiers perform better than the traditional MLP; ii) classification accuracies of the two neuro-fuzzy classifiers are comparable; and iii) the TSH classifier requires to train less background knowledge than FMLP.

  16. Overall noise characteristics of reduced images on liquid crystal display and advantages of independent subpixel driving technology.

    Science.gov (United States)

    Yamazaki, Asumi; Ichikawa, Katsuhiro; Kodera, Yoshie; Funahashi, Masao

    2013-02-01

    During soft-copy diagnoses, medical images with a large number of matrices often need to display reduced images on liquid crystal displays (LCDs) because of the spatial resolution limitation of LCDs. A new technology, known as independent subpixel driving (ISD), was recently applied to clinical uses aiming to improve the spatial resolution. The authors' study demonstrates the overall noise characteristics of images displayed on a LCD at various display magnifications, with and without ISD application. Measurements of the overall noise power spectra (NPS) of x-ray images displayed on LCD were performed at varying display magnifications, with and without ISD. The NPS of displayed images in several display situations were also simulated based on hypothetical noise factors. The measured and simulated NPS showed that noise characteristics worsened when the display magnification was reduced, due to aliasing errors. The overall noise characteristics were attributed to luminance-value fluctuation converted from pixel values, image-interpolation effects, inherent noise, and blurring of the LCD. ISD improved the noise characteristics because it suppressed noise increments by aliasing errors. ISD affected the noise-characteristic advantages of reduced images displayed on LCDs, particularly at low frequencies.

  17. PSICIC: noise and asymmetry in bacterial division revealed by computational image analysis at sub-pixel resolution.

    Directory of Open Access Journals (Sweden)

    Jonathan M Guberman

    2008-11-01

    Full Text Available Live-cell imaging by light microscopy has demonstrated that all cells are spatially and temporally organized. Quantitative, computational image analysis is an important part of cellular imaging, providing both enriched information about individual cell properties and the ability to analyze large datasets. However, such studies are often limited by the small size and variable shape of objects of interest. Here, we address two outstanding problems in bacterial cell division by developing a generally applicable, standardized, and modular software suite termed Projected System of Internal Coordinates from Interpolated Contours (PSICIC that solves common problems in image quantitation. PSICIC implements interpolated-contour analysis for accurate and precise determination of cell borders and automatically generates internal coordinate systems that are superimposable regardless of cell geometry. We have used PSICIC to establish that the cell-fate determinant, SpoIIE, is asymmetrically localized during Bacillus subtilis sporulation, thereby demonstrating the ability of PSICIC to discern protein localization features at sub-pixel scales. We also used PSICIC to examine the accuracy of cell division in Esherichia coli and found a new role for the Min system in regulating division-site placement throughout the cell length, but only prior to the initiation of cell constriction. These results extend our understanding of the regulation of both asymmetry and accuracy in bacterial division while demonstrating the general applicability of PSICIC as a computational approach for quantitative, high-throughput analysis of cellular images.

  18. Early plant succession in loblolly pine plantations as affected by vegetation management

    Science.gov (United States)

    James H. Miller; B.R. Zutter; S.M. Zedaker; M. Boyd Edwards; Ray A. Newbold

    1995-01-01

    A common study design has been used at 13 locations across the South to examine loblolly pine (Pinus taeda L.) plantations established using four vegetation control treatments after mechanical site preparation: (a) No Control, (b) Woody Control, (c) Herbaceous Controlfor 4 yr, and (d) Total Control. This research, the Competition Omission Monitoring...

  19. Microbial Communities in Cerrado Soils under Native Vegetation Subjected to Prescribed Fires and Under Pasture

    Science.gov (United States)

    The objective of this work was to evaluate the effects of fire regimes and vegetation cover on the structure and dynamics of soil microbial communities, through phospholipid fatty acid (PLFA) analysis. Comparisons were made between native areas with different woody covers ("cerra...

  20. Polypropylene/hemp woody core fiber composites: Morphology, mechanical, thermal properties, and water absorption behaviors

    OpenAIRE

    Chakaphan Ngaowthong; Vilai Rungsardthong; Suchart Siengchin

    2016-01-01

    Natural fiber composites composed of polypropylene, maleic anhydride-graft-polypropylene, and hemp woody core fiber were produced by two-roll mill mixing. The hemp woody core fiber was treated by alkaline. The morphology of the polypropylene/hemp woody core fiber composites was studied by scanning electron microscopy technique. The mechanical and thermo-mechanical properties of the polypropylene/hemp woody core fiber composites were determined in tensile, flexural tests, and thermogravimetric...

  1. Determinants of vegetation distribution at continental scale. The contribution of natural and anthropogenic factors

    DEFF Research Database (Denmark)

    Greve, Michelle; Svenning, J.-C.; Lykke, Anne Mette

    2011-01-01

    vegetation distribution across Africa. Vegetation types were extracted from the Global Land Cover Map for the year 2000, and the distribution of vegetation types modelled in terms of climate, soil and topography. Annual precipitation was the best predictor of the distribution of all vegetation types......It has long been debated what determines distribution of vegetation types, though this has rarely been tested at continental scale. We thus aimed to determine which vegetation types are most accurately predicted by natural environmental factors, and which of these factors best predict current......, and response curves showed that, at lower rainfall levels, an increase in precipitation brought on vegetation types with greater woody cover, though this pattern disappeared at higher rainfall levels. Subsequently, the influence of current and historic human impacts on the distribution of vegetation types...

  2. Textural analysis of historical aerial photography to characterize woody plant encroachment in South African savanna

    Science.gov (United States)

    Andrew T. Hudak; Carol A. Wessman

    1998-01-01

    Transitions from grassland to shrubland through woody plant encroachment result in potentially significant shifts in savanna ecosystem function. Given high resolution imagery, a textural index could prove useful for mapping woody plant densities and monitoring woody plant encroachment across savanna landscapes. Spatial heterogeneity introduced through mixtures of...

  3. Woody biomass utilization trends, barriers, and strategies: Perspectives of U.S. Forest Service managers

    Science.gov (United States)

    Shiloh Sundstrom; Max Nielsen-Pincus; Cassandra Moseley; Sarah. McCaffrey

    2012-01-01

    The use of woody biomass is being promoted across the United States as a means of increasing energy independence, mitigating climate change, and reducing the cost of hazardous fuels reduction treatments and forest restoration projects. The opportunities and challenges for woody biomass use on the national forest system are unique. In addition to making woody biomass...

  4. Post-fire logging reduces surface woody fuels up to four decades following wildfire

    Science.gov (United States)

    David W. Peterson; Erich Kyle Dodson; Richy J. Harrod

    2015-01-01

    Severe wildfires create pulses of dead trees that influence future fuel loads, fire behavior, and fire effects as they decay and deposit surface woody fuels. Harvesting fire-killed trees may reduce future surface woody fuels and related fire hazards, but the magnitude and timing of post-fire logging effects on woody fuels have not been fully assessed. To address this...

  5. Use of AIRSAR to identify woody shrub invasion and other indicators of desertification in the Jornada LTER

    Science.gov (United States)

    Musick, H. Brad; Schaber, Gerald G.; Breed, Carol S.

    1995-01-01

    The replacement of semidesert grassland by woody shrubland is a widespread form of desertification. This change in physiognomy and species composition tends to sharply reduce the productivity of the land for grazing by domestic livestock, increase soil erosion and reduce soil fertility, and greatly alter many other aspects of ecosystem structure and functioning. Remote sensing methods are needed to assess and monitor shrubland encroachment. Detection of woody shrubs at low density would provide a particularly useful baseline on which to access changes, because an initially low shrub density often tends to increase even after cessation of the disturbance (e.g., overgrazing, drought, or fire suppression) responsible for triggering the initial stages of the invasion (Grover and Musick, 1990). Limited success has been achieved using optical remote sensing. In contrast to other forms of desertification, biomass does not consistently decrease with a shift from grassland to shrubland. Estimation of green vegetation amount (e.g., by NDVI) is thus of limited utility, unless the shrubs and herbaceous plants differ consistently in phenology and the area can be viewed during a season when only one of these is green. The objective of this study was to determine if the potential sensitivity of active microwave remote sensing to vegetation structure could be used to assess the degree of shrub invasion of grassland. Polarimetric Airborne Synthetic Aperture Radar (AIRSAR) data were acquired for a semiarid site containing varied mixtures of shrubs and herbaceous vegetation and compared with ground observations of vegetation type and other landsurface characteristics. In this preliminary report we examine the response of radar backscatter intensity to shrub density. The response of other multipolarization parameters will be examined in future work.

  6. Vegetation survey of PEN Branch wetlands

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    A survey was conducted of vegetation along Pen Branch Creek at Savannah River Site (SRS) in support of K-Reactor restart. Plants were identified to species by overstory, understory, shrub, and groundcover strata. Abundance was also characterized and richness and diversity calculated. Based on woody species basal area, the Pen Branch delta was the most impacted, followed by the sections between the reactor and the delta. Species richness for shrub and groundcover strata were also lowest in the delta. No endangered plant species were found. Three upland pine areas were also sampled. In support of K Reactor restart, this report summarizes a study of the wetland vegetation along Pen Branch. Reactor effluent enters Indian Grove Branch and then flows into Pen Branch and the Pen Branch Delta.

  7. Woody tissue analysis using an element ratio technique (DRIS)

    Science.gov (United States)

    Kurt H. Riitters; L.F. Ohmann; D.F. Grigal

    1991-01-01

    The diagnosis and recommendation integrated system (DRIS) was used to describe the variation of 12 elements in woody tree tissue and balsam fir (Abies balsamae (L.) Mill.), sugar maple (Acer saccharum Marsh.), jack pine (Pinus banksiana Lamb.), red pine (Pinus resinosa alt.), and aspen (

  8. Simulating the productivity of desert woody shrubs in southwestern Texas

    Science.gov (United States)

    In the southwestern U.S., many rangelands have converted from native grasslands to woody shrublands dominated by creosotebush (Larrea tridentate) and honey mesquite (Prosopis glandulosa), threatening ecosystem health. Both creosotebush and mesquite have well-developed long root systems that allow t...

  9. Assessing The Ecological Status Of Woody Plant Species At Eroded ...

    African Journals Online (AJOL)

    Woody plant species up to 0.10 m and above in height growing in and within 0.5 m from the edges of ten gully erosion areas of Abia and Imo states of Nigeria were enumerated in January and July 2000 through July 2003. Questionnaires were served to find the causal factors of each gully. The plants were enumerated and ...

  10. Damage to buds and shoots of coniferous woody plants

    DEFF Research Database (Denmark)

    Witzell, J.; Matsiakh, I.; Poljakovic Pajnik, L.

    2017-01-01

    This guide is intended as an aid for managers of sentinel plantings, botanical gardens or arboreta, as well as phytosanitary inspectors, who may have knowledge of common pests and diseases of woody plants, but may not know the likely cause of damage that they have not encountered before. It aims...

  11. Bioenergy from forests: The power potential of woody biomass

    Science.gov (United States)

    John Kirkland; David Nicholls

    2015-01-01

    The elevated intensity of wildfire seasons in the American West combined with political, environmental, and economic issues surrounding the use of coal and oil are spurring a growing interest in the use of woody biomass as a fuel for heating and electrical generation.David Nicholls, a forest products technologist at the Alaska Wood Utilization Research and...

  12. Interplay of Regeneration, Structure and Uses of Some Woody ...

    African Journals Online (AJOL)

    Of these, the highest proportion is the angiosperm (represented by 193 species) followed by pteridophyta (16 species); the least represented being the gymnosperms (represented by 2 exotic and 2 indigenous species). Structural and regeneration studies of some woody species indicated that there are species that require ...

  13. Non-structural carbohydrates in woody plants compared among laboratories

    NARCIS (Netherlands)

    Quentin, Audrey G.; Pinkard, Elizabeth A.; Ryan, Michael G.; Tissue, David T.; Baggett, Scott L.; Adams, Henry D.; Maillard, Pascale; Marchand, Jacqueline; Landhäusser, Simon M.; Lacointe, André; Gibon, Yves; Anderegg, William R.L.; Asao, Shinichi; Atkin, Owen K.; Bonhomme, Marc; Claye, Caroline; Chow, Pak S.; Clément-Vidal, Anne; Davies, Noel W.; Dickman, Turin L.; Dumbur, Rita; Ellsworth, David S.; Falk, Kristen; Galiano, Lucía; Grünzweig, José M.; Hartmann, Henrik; Hoch, Günter; Hood, Sharon; Jones, Joanna E.; Koike, Takayoshi; Kuhlmann, Iris; Lloret, Francisco; Maestro, Melchor; Mansfield, Shawn D.; Martínez-Vilalta, Jordi; Maucourt, Mickael; McDowell, Nathan G.; Moing, Annick; Muller, Bertrand; Nebauer, Sergio G.; Niinemets, Ülo; Palacio, Sara; Piper, Frida; Raveh, Eran; Richter, Andreas; Rolland, Gaëlle; Rosas, Teresa; Joanis, Brigitte Saint; Sala, Anna; Smith, Renee A.; Sterck, Frank; Stinziano, Joseph R.; Tobias, Mari; Unda, Faride; Watanabe, Makoto; Way, Danielle A.; Weerasinghe, Lasantha K.; Wild, Birgit; Wiley, Erin; Woodruff, David R.

    2015-01-01

    Non-structural carbohydrates (NSC) in plant tissue are frequently quantified to make inferences about plant responses to environmental conditions. Laboratories publishing estimates of NSC of woody plants use many different methods to evaluate NSC. We asked whether NSC estimates in the recent

  14. Determination of native woody landscape plants in Bursa and Uludag

    African Journals Online (AJOL)

    PRECIOUS

    2009-11-02

    Nov 2, 2009 ... shrubs, 7 treelets and 4 climber groups, around the region which are notified to be suitable for rural and urban planning with the intentions of solitary, group, alley, wind-break, ground cover and attractive flowering and fruit. Key words: Woody plants, landscape planning, Bursa-Uludag. INTRODUCTION.

  15. Developmental mechanisms regulating secondary growth in woody plants

    Science.gov (United States)

    Andrew Groover; Marcel Robischon

    2006-01-01

    Secondary growth results in the radial expansion of woody stems, and requires the coordination of tissue patterning, cell differentiation, and the maintenance of meristematic stem cells within the vascular cambium. Advances are being made towards describing molecular mechanisms that regulate these developmental processes, thanks in part to the application of new...

  16. Determination of native woody landscape plants in Bursa and Uludag

    African Journals Online (AJOL)

    Around Bursa and Uludag is a wide range of native woody plants of which are commonly used for landscape planning. The present study pointed out a total of 72 plant species, consisting of 36 trees, 32 shrubs, 7 treelets and 4 climber groups, around the region which are notified to be suitable for rural and urban planning ...

  17. 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...

  18. Assessment of Soil Seedbank Composition of Woody Species in ...

    African Journals Online (AJOL)

    Bheema

    forests. In present work, soil seedbank assessment of woody plant species was made in. Hgumbirda national forest priority area so as to evaluate composition ... Deforestation and conversion of land to permanent cultivation is the primary cause for ... In fact, restoration/rehabilitation of degraded lands is a subject receiving.

  19. Non-structural carbohydrates in woody plants compared among laboratories

    Science.gov (United States)

    Audrey G. Quentin; Elizabeth A. Pinkard; Michael G. Ryan; David T. Tissue; L. Scott Baggett; Henry D. Adams; Pascale Maillard; Jacqueline Marchand; Simon M. Landhausser; Andre Lacointe; Yves Gibon; William R. L. Anderegg; Shinichi Asao; Owen K. Atkin; Marc Bonhomme; Caroline Claye; Pak S. Chow; Anne Clement-Vidal; Noel W. Davies; L. Turin Dickman; Rita Dumbur; David S. Ellsworth; Kristen Falk; Lucía Galiano; Jose M. Grunzweig; Henrik Hartmann; Gunter Hoch; Sharon Hood; Joanna E. Jones; Takayoshi Koike; Iris Kuhlmann; Francisco Lloret; Melchor Maestro; Shawn D. Mansfield; Jordi Martinez-Vilalta; Mickael Maucourt; Nathan G. McDowell; Annick Moing; Bertrand Muller; Sergio G. Nebauer; Ulo Niinemets; Sara Palacio; Frida Piper; Eran Raveh; Andreas Richter; Gaelle Rolland; Teresa Rosas; Brigitte Saint Joanis; Anna Sala; Renee A. Smith; Frank Sterck; Joseph R. Stinziano; Mari Tobias; Faride Unda; Makoto Watanabe; Danielle A. Way; Lasantha K. Weerasinghe; Birgit Wild; Erin Wiley; David R. Woodruff

    2016-01-01

    Non-structural carbohydrates (NSC) in plant tissue are frequently quantified to make inferences about plant responses to environmental conditions. Laboratories publishing estimates of NSC of woody plants use many different methods to evaluate NSC. We asked whether NSC estimates in the recent literature could be quantitatively compared among studies. We also...

  20. Coarse woody debris in oak woodlands of California.

    Science.gov (United States)

    William D. Tietje; Karen L. Waddell; Justin K. Vreeland; Charles L. Bolsinger

    2002-01-01

    An extensive forest inventory was conducted to estimate the amount and distribution of coarse woody debris (CWD) on 5.6 million ac of woodlands in California that are outside of national forests and reserved areas. Woodlands consist primarily of oak (Quercus spp.) types and are defined as forestland incapable of producing commercial quantities of...

  1. Processing woody biomass with a modified horizontal grinder

    Science.gov (United States)

    Dana Mitchell; John Klepac

    2008-01-01

    This study documents the production rate and cost of producing woody biomass chips for use in a power plant. The power plant has specific raw material handling requirements. Output from a 3-knife chipper, a tub grinder, and a horizontal grinder was considered. None of the samples from these machines met the specifications needed. A horizontal grinder was modified to...

  2. Instability of the snowshoe hare and woody plant interaction.

    Science.gov (United States)

    Fox, John F; Bryant, John P

    1984-07-01

    We show that Alaskan woody plants respond to browsing in two ways that might destabilize a plantherbivore interaction and account for snowshoe hare population 'cycles'. (1) Browse production of preferred, earliersuccessional woody plants increases in response to moderate levels of browsing. Such yield increases are potentially destabilizing. Later successional woody plants show decreases in yield after moderate browsing, which is consistent with the persistence of snowshoe hares in late successional 'refuge' habitats (Keith 1966, Wolff 1980). (2) Many woody plants are destructively overbrowsed or girdled at the peak of the snowshoe hare cycle. The more palatable and plastic, early to mid successional plants respond by sprouting accompanied by juvenile reversion. Sprouts are markedly less palatable than mature shoots. We show here that sprout palatability and twig biomass are restored in 2-3 years for earlier successional plants, but palatability may not recover for 4-10 years in sprouts of some mid to late successional plants. The decrease in palatability helps to account for the snowshoe hare 'crash' (assuming that damage to more palatable plants is widespread during the 'peak'), and the 2-3 year time lag for recovery of more palatable species could account for (May 1974) the observed 8-11 year period of the hare cycles. Browse yield increases acting during the snowshoe hare population nadir and increase, and sprouting with juvenile reversion acting during the hare peak and decline can in principle account for the oscillatory nature and the observed 8-11 year periodicity of the snowshoe hare cycle.

  3. A century of woody plant encroachment in the dry Kimberley ...

    African Journals Online (AJOL)

    We used aerial and fixed-point repeat ground photographs, including historical photographs taken at the time of the Second Anglo-Boer War of 1899–1902, to assess the scale and timing of woody plant encroachment in the dry savannas near Kimberley in South Africa (mean annual rainfall = 300–400 mm). There were ...

  4. Woody species colonisation in relation to habitat productivity

    NARCIS (Netherlands)

    Smit, R.; Olff, H.

    1998-01-01

    A study was conducted to analyse the effect of habitat productivity on woody species colonisation. Three soil types were distinguished: a relatively poor sandy soil type (1), a somewhat richer sandy type (2) and a relatively rich sandy loamy type (3). Chronosequences were established on these three

  5. Savannah woody structure modelling and mapping using multi-frequency (X-, C- and L-band) Synthetic Aperture Radar data

    Science.gov (United States)

    Naidoo, Laven; Mathieu, Renaud; Main, Russell; Kleynhans, Waldo; Wessels, Konrad; Asner, Gregory; Leblon, Brigitte

    2015-07-01

    Structural parameters of the woody component in African savannahs provide estimates of carbon stocks that are vital to the understanding of fuelwood reserves, which is the primary source of energy for 90% of households in South Africa (80% in Sub-Saharan Africa) and are at risk of over utilisation. The woody component can be characterised by various quantifiable woody structural parameters, such as tree cover, tree height, above ground biomass (AGB) or canopy volume, each been useful for different purposes. In contrast to the limited spatial coverage of ground-based approaches, remote sensing has the ability to sense the high spatio-temporal variability of e.g. woody canopy height, cover and biomass, as well as species diversity and phenological status - a defining but challenging set of characteristics typical of African savannahs. Active remote sensing systems (e.g. Light Detection and Ranging - LiDAR; Synthetic Aperture Radar - SAR), on the other hand, may be more effective in quantifying the savannah woody component because of their ability to sense within-canopy properties of the vegetation and its insensitivity to atmosphere and clouds and shadows. Additionally, the various components of a particular target's structure can be sensed differently with SAR depending on the frequency or wavelength of the sensor being utilised. This study sought to test and compare the accuracy of modelling, in a Random Forest machine learning environment, woody above ground biomass (AGB), canopy cover (CC) and total canopy volume (TCV) in South African savannahs using a combination of X-band (TerraSAR-X), C-band (RADARSAT-2) and L-band (ALOS PALSAR) radar datasets. Training and validation data were derived from airborne LiDAR data to evaluate the SAR modelling accuracies. It was concluded that the L-band SAR frequency was more effective in the modelling of the CC (coefficient of determination or R2 of 0.77), TCV (R2 of 0.79) and AGB (R2 of 0.78) metrics in Southern African

  6. Quantitative woody cover reconstructions from eastern continental Asia of the last 22 kyr reveal strong regional peculiarities

    Science.gov (United States)

    Tian, Fang; Cao, Xianyong; Dallmeyer, Anne; Ni, Jian; Zhao, Yan; Wang, Yongbo; Herzschuh, Ulrike

    2016-04-01

    We present a calibration-set based on modern pollen and satellite-based Advanced Very High Resolution Radiometer (AVHRR) observations of woody cover (including needleleaved, broadleaved and total tree cover) in eastern continental Asia, which shows good performance under cross-validation with the modern analogue technique (all the coefficients of determination between observed and predicted values are greater than 0.65). The calibration-set is used to reconstruct woody cover from a taxonomically harmonized and temporally standardized fossil pollen dataset (including 274 cores) with 500-year resolution over the last 22 kyr. The spatial range of forest has not noticeably changed in eastern continental Asia during the last 22 kyr, although woody cover has, especially at the margin of the eastern Tibetan Plateau and in the forest-steppe transition area of north-central China. Vegetation was sparse during the LGM in the present forested regions, but woody cover increased markedly at the beginning of the Bølling/Allerød period (B/A; ca. 14.5 ka BP) and again at the beginning of the Holocene (ca. 11.5 ka BP), and is related to the enhanced strength of the East Asian Summer Monsoon. Forest flourished in the mid-Holocene (ca. 8 ka BP) possibly due to favourable climatic conditions. In contrast, cover was stable in southern China (high cover) and arid central Asia (very low cover) throughout the investigated period. Forest cover increased in the north-eastern part of China during the Holocene. Comparisons of these regional pollen-based results with simulated forest cover from runs of a global climate model (for 9, 6 and 0 ka BP (ECHAM5/JSBACH ∼1.125° spatial resolution)) reveal many similarities in temporal change. The Holocene woody cover history of eastern continental Asia is different from that of other regions, likely controlled by different climatic variables, i.e. moisture in eastern continental Asia; temperature in northern Eurasia and North America.

  7. Remediation of heavy metal-contaminated forest soil using recycled organic matter and native woody plants.

    Science.gov (United States)

    Helmisaari, H-S; Salemaa, M; Derome, J; Kiikkilä, O; Uhlig, C; Nieminen, T M

    2007-01-01

    The main aim of this study was to determine how the application of a mulch cover (a mixture of household biocompost and woodchips) onto heavy metal-polluted forest soil affects (i) long-term survival and growth of planted dwarf shrubs and tree seedlings and (ii) natural revegetation. Native woody plants (Pinus sylvestris, Betula pubescens, Empetrum nigrum, and Arctostaphylos uva-ursi) were planted in mulch pockets on mulch-covered and uncovered plots in summer 1996 in a highly polluted Scots pine stand in southwest Finland. Spreading a mulch layer on the soil surface was essential for the recolonization of natural vegetation and increased dwarf shrub survival, partly through protection against drought. Despite initial mortality, transplant establishment was relatively successful during the following 10 yr. Tree species had higher survival rates, but the dwarf shrubs covered a larger area of the soil surface during the experiment. Especially E. nigrum and P. sylvestris proved to be suitable for revegetating heavy metal-polluted and degraded forests. Natural recolonization of pioneer species (e.g., Epilobium angustifolium, Taraxacum coll., and grasses) and tree seedlings (P. sylvestris, Betula sp., and Salix sp.) was strongly enhanced on the mulched plots, whereas there was no natural vegetation on the untreated plots. These results indicate that a heavy metal-polluted site can be ecologically remediated without having to remove the soil. Household compost and woodchips are low-cost mulching materials that are suitable for restoring heavy metal-polluted soil.

  8. Woodiness within the Spermacoceae–Knoxieae alliance (Rubiaceae): retention of the basal woody condition in Rubiaceae or recent innovation?

    NARCIS (Netherlands)

    Lens, F.; Groeninkx, I.; Smets, E.; Dessein, S.

    2009-01-01

    † Background and Aims The tribe Spermacoceae is essentially a herbaceous Rubiaceae lineage, except for some species that can be described as ‘woody’ herbs, small shrubs to treelets, or lianas. Its sister tribe Knoxieae contains a large number of herbaceous taxa, but the number of woody taxa is

  9. Interactions of Woody Biofuel Feedstock Production Systems with Water Resources: Considerations for Sustainability

    Energy Technology Data Exchange (ETDEWEB)

    Trettin, Carl C. [US Forest Service Center for Forested Wetlands Research, Cordesville, SC (United States); Amatya, Devendra [US Forest Service Center for Forested Wetlands Research, Cordesville, SC (United States); Coleman, Mark [US Forest Service Center for Forested Wetlands Research, Cordesville, SC (United States)

    2008-04-15

    Water resources are important for the production of woody biofuel feedstocks. It is necessary to ensure that production systems do not adversely affect the quantity or quality of surface and ground water. The effects of woody biomass plantations on water resources are largely dependent on the prior land use and the management regime. Experience from both irrigated and non-irrigated systems has demonstrated that woody biofuel production systems do not impair water quality. Water quality actually improves from conversion of idle or degraded agricultural lands to woody biomass plantations. Site water balance may be altered by cultivation of woody biomass plantations relative to agricultural use, due to increases in evapostranspiration (ET) and storage. Incorporation of woody biomass production plantations within the landscape provides an opportunity to improve the quality of runoff water and soil conservation. Finally, given the centrality of water resources to the sustainability of ecosystem services and other values derived, the experience with woody biofuels feedstock production systems is positive.

  10. Sensitivity of woody carbon stocks to bark investment strategy in Neotropical savannas and forests

    Science.gov (United States)

    Trugman, Anna T.; Medvigy, David; Hoffmann, William A.; Pellegrini, Adam F. A.

    2018-01-01

    Fire frequencies are changing in Neotropical savannas and forests as a result of forest fragmentation and increasing drought. Such changes in fire regime and climate are hypothesized to destabilize tropical carbon storage, but there has been little consideration of the widespread variability in tree fire tolerance strategies. To test how aboveground carbon stocks change with fire frequency and composition of plants with different fire tolerance strategies, we update the Ecosystem Demography model 2 (ED2) with (i) a fire survivorship module based on tree bark thickness (a key fire-tolerance trait across woody plants in savannas and forests), and (ii) plant functional types representative of trees in the region. With these updates, the model is better able to predict how fire frequency affects population demography and aboveground woody carbon. Simulations illustrate that the high survival rate of thick-barked, large trees reduces carbon losses with increasing fire frequency, with high investment in bark being particularly important in reducing losses in the wettest sites. Additionally, in landscapes that frequently burn, bark investment can broaden the range of climate and fire conditions under which savannas occur by reducing the range of conditions leading to either complete tree loss or complete grass loss. These results highlight that tropical vegetation dynamics depend not only on rainfall and changing fire frequencies but also on tree fire survival strategy. Further, our results indicate that fire survival strategy is fundamentally important in regulating tree size demography in ecosystems exposed to fire, which increases the preservation of aboveground carbon stocks and the coexistence of different plant functional groups.

  11. Sensitivity of woody carbon stocks to bark investment strategy in Neotropical savannas and forests

    Directory of Open Access Journals (Sweden)

    A. T. Trugman

    2018-01-01

    Full Text Available Fire frequencies are changing in Neotropical savannas and forests as a result of forest fragmentation and increasing drought. Such changes in fire regime and climate are hypothesized to destabilize tropical carbon storage, but there has been little consideration of the widespread variability in tree fire tolerance strategies. To test how aboveground carbon stocks change with fire frequency and composition of plants with different fire tolerance strategies, we update the Ecosystem Demography model 2 (ED2 with (i a fire survivorship module based on tree bark thickness (a key fire-tolerance trait across woody plants in savannas and forests, and (ii plant functional types representative of trees in the region. With these updates, the model is better able to predict how fire frequency affects population demography and aboveground woody carbon. Simulations illustrate that the high survival rate of thick-barked, large trees reduces carbon losses with increasing fire frequency, with high investment in bark being particularly important in reducing losses in the wettest sites. Additionally, in landscapes that frequently burn, bark investment can broaden the range of climate and fire conditions under which savannas occur by reducing the range of conditions leading to either complete tree loss or complete grass loss. These results highlight that tropical vegetation dynamics depend not only on rainfall and changing fire frequencies but also on tree fire survival strategy. Further, our results indicate that fire survival strategy is fundamentally important in regulating tree size demography in ecosystems exposed to fire, which increases the preservation of aboveground carbon stocks and the coexistence of different plant functional groups.

  12. Relationship between the relative limitation and resorption efficiency of nitrogen vs phosphorus in woody plants.

    Science.gov (United States)

    Han, Wenxuan; Tang, Luying; Chen, Yahan; Fang, Jingyun

    2013-01-01

    Most previous studies have ascribed variations in the resorption of a certain plant nutrient to its corresponding environmental availability or level in tissues, regardless of the other nutrients' status. However, given that plant growth relies on both sufficient and balanced nutrient supply, the nutrient resorption process should not only be related to the absolute nutrient status, but also be regulated by the relative limitation of the nutrient. Here, based on a global woody-plants dataset from literature, we test the hypothesis that plants resorb proportionately more nitrogen (or phosphorus) when they are nitrogen (or phosphorus) limited, or similar proportions of nitrogen (N) and phosphorus (P) when co-limited by both nutrients (the relative resorption hypothesis). Using the N:P ratio in green foliage as an indicator of nutrient limitation, we found an inverse relationship between the difference in the proportionate resorption of N vs P and this foliar N:P ratio, consistent across species, growth-forms, and vegetation-types globally. Moreover, according to the relative resorption hypothesis, communities with higher/lower foliar N:P (more likely P/N limited) tend to produce litter with disproportionately higher/lower N:P, causing a worsening status of P/N availability; this positive feedback may somehow be counteracted by several negative-feedback mechanisms. Compared to N, P generally shows higher variability in resorption efficiency (proportion resorbed), and higher resorption sensitivity to nutrient availability, implying that the resorption of P seems more important for plant nutrient conservation and N:P stoichiometry. Our findings elucidate the nutrient limitation effects on resorption efficiency in woody plants at the global scale, and thus can improve the understanding of nutrient resorption process in plants. This study also suggests the importance of the foliar N:P ratio as a key parameter for biogeochemical modeling, and the relative resorption

  13. Evidence of physiological decoupling from grassland ecosystem drivers by an encroaching woody shrub.

    Directory of Open Access Journals (Sweden)

    Jesse B Nippert

    Full Text Available Shrub encroachment of grasslands is a transformative ecological process by which native woody species increase in cover and frequency and replace the herbaceous community. Mechanisms of encroachment are typically assessed using temporal data or experimental manipulations, with few large spatial assessments of shrub physiology. In a mesic grassland in North America, we measured inter- and intra-annual variability in leaf δ(13C in Cornus drummondii across a grassland landscape with varying fire frequency, presence of large grazers and topographic variability. This assessment of changes in individual shrub physiology is the largest spatial and temporal assessment recorded to date. Despite a doubling of annual rainfall (in 2008 versus 2011, leaf δ(13C was statistically similar among and within years from 2008-11 (range of -28 to -27‰. A topography*grazing interaction was present, with higher leaf δ(13C in locations that typically have more bare soil and higher sensible heat in the growing season (upland topographic positions and grazed grasslands. Leaf δ(13C from slopes varied among grazing contrasts, with upland and slope leaf δ(13C more similar in ungrazed locations, while slopes and lowlands were more similar in grazed locations. In 2011, canopy greenness (normalized difference vegetation index - NDVI was assessed at the centroid of individual shrubs using high-resolution hyperspectral imagery. Canopy greenness was highest mid-summer, likely reflecting temporal periods when C assimilation rates were highest. Similar to patterns seen in leaf δ(13C, NDVI was highest in locations that typically experience lowest sensible heat (lowlands and ungrazed. The ability of Cornus drummondii to decouple leaf physiological responses from climate variability and fire frequency is a likely contributor to the increase in cover and frequency of this shrub species in mesic grassland and may be generalizable to other grasslands undergoing woody encroachment.

  14. Potential of pest regulation by insectivorous birds in Mediterranean woody crops.

    Directory of Open Access Journals (Sweden)

    José M Rey Benayas

    Full Text Available Regulation of agricultural pests managing their natural enemies represents an alternative to chemical pesticides. We assessed the potential of insectivorous birds as pest regulators in woody crops located in central Spain. A total of 417 nest boxes installed in five field study sites (one vineyard, two fruit orchards, and two olive groves were monitored for use and breeding of insectivorous birds and other species for four consecutive years (2013-2016. At all field sites except the two olive groves, where birds never occupied the nest boxes, predation experiments were conducted with Greater wax moth (Galleria mellonella sentinel caterpillars, and food consumption by birds was estimated. Nesting of insectivorous birds, chiefly Great tit (Parus major, and sparrows (Passer domesticus and P. montanus increased over time, averaging 60% per field site in the vineyard and fruit orchards by the fourth year. Use of nest boxes by sparrows and by Garden dormouse (Eliomys quercinus was high at the fruit orchards (70% and the vineyard (30%, respectively. Micro-habitat characteristics (nest box level and meso-habitat characteristics (patch level strongly affected use of nest boxes and bird breeding (i.e. number of laid eggs and produced chicks in different years. Distance to natural or semi-natural vegetation did not consistently affect bird breeding, nor did we see consistent evidence of competition between adjacent breeding birds. Predation rates of sentinel caterpillars were approximately one-third higher near boxes with nesting birds (31.51 ± 43.13% than at paired distant areas without nest boxes (22.45% ± 38.58%. Food consumption by insectivorous birds per ha and breeding season were conservatively estimated to range from 0.02 kg in one fruit orchard to 0.15 kg in the vineyard. We conclude that installation of nest boxes in Mediterranean woody crops enhances populations of insectivorous birds that regulate pests, but that the effects are moderate and

  15. Assessing the impact of climate variability on catchment water balance and vegetation cover

    Directory of Open Access Journals (Sweden)

    X. Xu

    2012-01-01

    Full Text Available Understanding the interactions among climate, vegetation cover and the water cycle lies at the heart of the study of watershed ecohydrology. Recently, considerable attention is being paid to the effect of climate variability on catchment water balance and also associated vegetation cover. In this paper, we investigate the general pattern of long-term water balance and vegetation cover (as reflected by fPAR among 193 study catchments in Australia through statistical analysis. We then employ the elasticity analysis approach for quantifying the effects of climate variability on hydrologic partitioning (including total, surface and subsurface runoff and on vegetation cover (including total, woody and non-woody vegetation cover. Based on the results of statistical analysis, we conclude that annual runoff (R, evapotranspiration (E and runoff coefficient (R/P increase with vegetation cover for catchments in which woody vegetation is dominant and annual precipitation is relatively high. Control of water available on annual evapotranspiration in non-woody dominated catchments is relatively stronger compared to woody dominated ones. The ratio of subsurface runoff to total runoff (Rg/R also increases with woody vegetation cover. Through the elasticity analysis of catchment runoff, it is shown that precipitation (P in current year is the most important factor affecting the change in annual total runoff (R, surface runoff (Rs and subsurface runoff (Rg. The significance of other controlling factors is in the order of annual precipitation in previous years (P−1 and P−2, which represents the net effect of soil moisture and annual mean temperature (T in current year. Change of P by +1% causes a +3.35% change of R, a +3.47% change of Rs and a +2.89% change of

  16. L-band Synthetic Aperture Radar imagery performs better than optical datasets at retrieving woody fractional cover in deciduous, dry savannahs

    Science.gov (United States)

    Naidoo, Laven; Mathieu, Renaud; Main, Russell; Wessels, Konrad; Asner, Gregory P.

    2016-10-01

    Woody canopy cover (CC) is the simplest two dimensional metric for assessing the presence of the woody component in savannahs, but detailed validated maps are not currently available in southern African savannahs. A number of international EO programs (including in savannah landscapes) advocate and use optical LandSAT imagery for regional to country-wide mapping of woody canopy cover. However, previous research has shown that L-band Synthetic Aperture Radar (SAR) provides good performance at retrieving woody canopy cover in southern African savannahs. This study's objective was to evaluate, compare and use in combination L-band ALOS PALSAR and LandSAT-5 TM, in a Random Forest environment, to assess the benefits of using LandSAT compared to ALOS PALSAR. Additional objectives saw the testing of LandSAT-5 image seasonality, spectral vegetation indices and image textures for improved CC modelling. Results showed that LandSAT-5 imagery acquired in the summer and autumn seasons yielded the highest single season modelling accuracies (R2 between 0.47 and 0.65), depending on the year but the combination of multi-seasonal images yielded higher accuracies (R2 between 0.57 and 0.72). The derivation of spectral vegetation indices and image textures and their combinations with optical reflectance bands provided minimal improvement with no optical-only result exceeding the winter SAR L-band backscatter alone results (R2 of ∼0.8). The integration of seasonally appropriate LandSAT-5 image reflectance and L-band HH and HV backscatter data does provide a significant improvement for CC modelling at the higher end of the model performance (R2 between 0.83 and 0.88), but we conclude that L-band only based CC modelling be recommended for South African regions.

  17. Trends in woody vegetation cover in the Kruger National Park, South Africa, between 1940 and 1998

    CSIR Research Space (South Africa)

    Eckhardt, HC

    2000-06-01

    Full Text Available South Africa’s Kruger National Park is one of the largest conservation areas in Africa. In 1940, 1974 and 1998 changes in the cover and density of shrubs and trees were assessed from aerial photographs, and in 1984 and 1996 fixed-point photographs...

  18. Effects of Perennial Fires on the Woody Vegetation of Mole National ...

    African Journals Online (AJOL)

    . ... The greater proportion of the scars had reached an advanced stage and the affected individuals were either moribund or were likely to be killed by subsequent fires or toppled by the wind. Contrary to the popular opinion that fire generally ...

  19. Renewable energy from vegetation; Les energies renouvelables d'origine vegetale

    Energy Technology Data Exchange (ETDEWEB)

    Sales, C. [Centre francais de cooperation international en recherche agronomique pour le developpement (France)

    2009-07-15

    Currently, vegetation accounts for 3 major types of energy sources, notably woody biomass, starches and vegetable oils. Bio-ethanol and biodiesel is produced from the fermentation of starches, such as sugar cane, beet sugar, sorghum, corn and potatoes. Biofuels can be produced from palm tree oil, coconut oil , soya oil, sunflower oil or any type of vegetable based oil. This article discussed energy efficiency issues and the environmental impact of developing these energies. In general, the lower energy efficiency of the starches can be attributed to the enzymes responsible for the catalysis. The article also reviewed the thermochemistry and energy efficiency regarding second generation fuels. It also discussed the burning of biomass, including woody biomass, forest waste and agricultural waste. 1 ref., 2 figs.

  20. Phosphorus nutrition of woody plants: many questions - few answers.

    Science.gov (United States)

    Rennenberg, H; Herschbach, C

    2013-09-01

    Phosphorus (P) acquisition, cycling and use efficiency has been investigated intensively with herbaceous plants. It is known that local as well as systemic signalling contributes to the control of P acquisition. Woody plants are long-lived organisms that adapt their life cycle to the changing environment during their annual growth cycle. Little is known about P acquisition and P cycling in perennial plants, especially regarding storage and mobilisation, its control by systemic and environmental factors, and its interaction with the largely closed ecosystem-level P cycle. The present report presents a view on open questions on plant internal P cycling in woody plants. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

  1. Suitable utilization of woody plants for hibitation on Mars

    Science.gov (United States)

    Tomita-Yokotani, Kaori; Baba, Keiichi; Suzuki, Toshisada; Kimura, Shunta; Sato, Seigo; Katoh, Hiroshi; Abe, Yusuke; Katayama, Takeshi

    2016-07-01

    We have been investigating the usefulness of woody plants for habitation on Mars. During our research, we have found that woody plants have several properties which can be utilized for therapy and materials for enrage and construction even on Mars. Japanese people traditionally believe that "Bonsai" have therapeudic properties. Trees can become carbon fuel which can be used as energy on Mars. Tree materials could be used as a tool in closed bio-ecosystems such as for the purification and/or separation of solutions in an environment in space. Here, we will show some results of their abilities, the water leakage and vacuum seal test, separation of solutions using carbon materials made from trees. At the initiation of this research, we named the trees used as material for the experiment related to space environments "CosmoBon", small bonsai tree. To establish our research, as the first step, we will try to do the experiment using "CosmoBon".

  2. Biomass Estimation of Dry Tropical Woody Species at Juvenile Stage

    Directory of Open Access Journals (Sweden)

    R. K. Chaturvedi

    2012-01-01

    Full Text Available Accurate characterization of biomass in different forest components is important to estimate their contribution to total carbon stock. Due to lack of allometric equations for biomass estimation of woody species at juvenile stage, the carbon stored in this forest component is ignored. We harvested 47 woody species at juvenile stage in a dry tropical forest and developed regression models for the estimation of above-ground biomass (AGB. The models including wood-specific gravity ( exhibited higher 2 than those without . The model consisting of , stem diameter (, and height ( not only exhibited the highest 2 value but also had the lowest standard error of estimate. We suggest that -based regression model is a viable option for nondestructive estimation of biomass of forest trees at juvenile stage.

  3. An Ordination of the Vegetation of Ntshongweni, Natal*

    Directory of Open Access Journals (Sweden)

    J. W. Morris

    1969-11-01

    Full Text Available The physiography, soils, climate and dense woody vegetation are briefly described for Ntshongweni, a cone-shaped hill in Natal, South Africa (29° 51' S and 30° 43' E. A primary ordination of the woody plants, based on Bray & Curtis’s (1957 method, was carried out using 60 quadrats. Four stand noda were delimited and another four noda within a secondary ordination of a cluster of quadrats which could not be interpreted within the primary ordination. Edaphic and atmospheric moisture conditions and slope aspect were proposed as the main site factors correlated with species performance. Tables of density, local frequency and constancy for species occurring in each nodum were drawn up.

  4. Investing carbon offsets in woody forests - the best solution for California?

    Science.gov (United States)

    Dass, P.; Houlton, B. Z.; Warlind, D.

    2016-12-01

    Increasing atmospheric carbon dioxide (CO2) concentrations from fossil fuel combustion, land conversion and biomass burning are principal to climate change and its manifolds risks on human health, the environment and the global economy. Effective mitigation of climate change thereby involves cutting fossil-fuel emissions at the source or capturing CO2 in engineered or natural ecosystem stocks, or both. The lifetime of CO2 in the atmosphere exceeds 100 years; thus, in the case of CO2 sequestration by natural ecosystems, the residence time of soil and vegetation carbon(C) is a critical component of the efficacy of C offsets in the marketplace, particularly in local to global Cap and Trade frameworks. Here we use a land-surface model to analyze trade-offs in C investment into natural forest vs. grassland sinks and the role of fire in driving the most sustained pathways of CO2 sequestration under Cap and Trade policies. We focus on the California Climate Exchange and AB32 as the model system for examining risks of CO2 offset investments by considering model-based scenarios of (a.) natural woody forests (mixture of trees, shrubs and grasslands) or (b.) pure grasslands (no woody vegetation allowed) under conditions of drought and changes in fire frequency. While forests capture more carbon than grasslands, the latter stores a greater fraction of C in below ground stocks, making it less vulnerable to climate-driven disturbances. Preliminary results for simulations carried out for the last century for the state of California corroborate this hypothesis: while trees capture 100 GgCyr-1 more than grasses, CO2 emissions due to fire is less by 20 GgCyr-1 from grasslands when compared to forest environments. Since policies need to regard potential future scenarios, we present results that investigate how the alternate systems of trees and grasses respond to (i.) the environmental conditions of the no-mitigation scenario (RCP 8.5) through the year 2100, (ii.) periods of extended

  5. A Framework Based on 2-D Taylor Expansion for Quantifying the Impacts of Sub-Pixel Reflectance Variance and Covariance on Cloud Optical Thickness and Effective Radius Retrievals Based on the Bi-Spectral Method

    Science.gov (United States)

    Zhang, Z.; Werner, F.; Cho, H. -M.; Wind, G.; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, Kerry

    2016-01-01

    The bi-spectral method retrieves cloud optical thickness and cloud droplet effective radius simultaneously from a pair of cloud reflectance observations, one in a visible or near-infrared (VISNIR) band and the other in a shortwave infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved and re. In the literature, the retrievals of and re are often assumed to be independent and considered separately when investigating the impact of sub-pixel cloud reflectance variations on the bi-spectral method. As a result, the impact on is contributed only by the sub-pixel variation of VISNIR band reflectance and the impact on re only by the sub-pixel variation of SWIR band reflectance. In our new framework, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VISNIR and SWIR cloud reflectances and their covariance on the and re retrievals. This framework takes into account the fact that the retrievals are determined by both VISNIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the and re retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VISNIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval. We test our framework using synthetic cloud fields from a large-eddy simulation and real observations from Moderate Resolution Imaging Spectroradiometer. The predicted results based on our framework agree very well with the numerical simulations. Our framework can be used

  6. A Framework Based on 2-D Taylor Expansion for Quantifying the Impacts of Subpixel Reflectance Variance and Covariance on Cloud Optical Thickness and Effective Radius Retrievals Based on the Bispectral Method

    Science.gov (United States)

    Zhang, Z.; Werner, F.; Cho, H.-M.; Wind, G.; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, K.

    2016-01-01

    The bispectral method retrieves cloud optical thickness (t) and cloud droplet effective radius (re) simultaneously from a pair of cloud reflectance observations, one in a visible or near-infrared (VIS/NIR) band and the other in a shortwave infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring subpixel variations of cloud reflectances can lead to a significant bias in the retrieved t and re. In the literature, the retrievals of t and re are often assumed to be independent and considered separately when investigating the impact of subpixel cloud reflectance variations on the bispectral method. As a result, the impact on t is contributed only by the subpixel variation of VIS/NIR band reflectance and the impact on re only by the subpixel variation of SWIR band reflectance. In our new framework, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of subpixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the t and re retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how subpixel cloud reflectance variations impact the t and re retrievals based on the bispectral method. In particular, our framework provides a mathematical explanation of how the subpixel variation in VIS/NIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval. We test our framework using synthetic cloud fields from a large-eddy simulation and real observations from Moderate Resolution Imaging Spectroradiometer. The predicted results based on our framework agree very well with the numerical simulations. Our

  7. Land Cover Vegetation Changes and Hydrology in Central Texas

    Science.gov (United States)

    Banta, J. R.; Slattery, R.

    2013-12-01

    Encroachment of woody vegetation into traditional savanna grassland ecosystems in central Texas has largely been attributed to land use practices of settlers, most notably overgrazing and fire suppression. Implementing changes in land cover vegetation (removing the woody vegetation and allowing native grasses to reestablish in the area, commonly referred to as brush management), could potentially change the hydrology in a watershed. The U.S. Geological Survey, in cooperation with several local, State, and Federal agencies, studied the hydrologic effects of ashe juniper (Juniperus ashei) removal as a brush management conservation practice in the Honey Creek State Natural Area in Comal County, Tex. Two adjacent watersheds of 104 and 159 hectares were used in a paired study. Rainfall, streamflow, evapotranspiration (Bowen ratio method), and water quality data were collected in both watersheds. Using a hydrologic mass balance approach, rainfall was allocated to surface-water runoff, evapotranspiration, and potential groundwater recharge. Groundwater recharge was not directly measured, but estimated as the residual of the hydrologic mass balance. After hydrologic data were collected in both watersheds for 3 years, approximately 80 percent of the woody vegetation (ashe juniper) was selectively removed from the 159 hectare watershed (treatment watershed). Brush management was not implemented in the other (reference) watershed. Hydrologic data were collected in both watersheds for six years after brush management implementation. The resulting data were examined for differences in the hydrologic budget between the reference and treatment watersheds as well as between pre- and post-brush management periods to assess effects of the treatment. Results indicate there are differences in the hydrologic budget and water quality between the reference and treatment watersheds, as well as between pre- and post-brush management periods.

  8. Vegetation barrier and tillage effects on runoff and sediment in an alley crop system on a Luvisol in Burkina Faso

    NARCIS (Netherlands)

    Spaan, W.P.; Sikking, A.F.S.; Hoogmoed, W.B.

    2005-01-01

    The effects of vegetation barriers and tillage on runoff and soil loss were evaluated in an alley crop system at a research station in central Burkina Faso. On a 2% slope of a sandy loam various local species (grasses, woody species and a succulent) were planted as conservation barriers in order to

  9. Restoring Upland Forests to Longleaf Pine: Initial Effects on Fuel Load, Fire Danger, Forest Vegetation, and Beetle Populations

    Science.gov (United States)

    James D. Haywood; Tessa A. Bauman; Richard A. Goyer; Finis L. Harris

    2004-01-01

    Without fire in the Southeastern United States, loblolly pine (Pinus taeda L.) often becomes the overstory dominant on sites historically dominated by longleaf pine (P. palustris Mill.). Beneath the loblolly pine canopy a mature midstory and understory develops of woody vegetation supporting draped fuels. The resulting deep shade...

  10. Prescribed fire and brush removal affect vegetation, fuel loads, and abundance of selected beetle populations in pine stands

    Science.gov (United States)

    James D. Haywood; Tessa A. Bauman; Richard A. Goyer; Gerald J. Lenhard

    2015-01-01

    Three forest sites were selected in Louisiana in early 2001. On each site, three treatments were applied: (1) Check: no further management; (2) PF: prescribed fire was applied in May 2001 and June 2003; and (3) PF-MPC: between the two prescribed fires, midstory and understory woody vegetation was masticated with mechanical equipment in July 2002. Management did not...

  11. Microbial Accessibility of Soil Organic Matter Following Woody Plant ýEncroachment Into Grasslands

    Science.gov (United States)

    Creamer, C. A.; Boutton, T. W.; Filley, T. R.

    2008-12-01

    youngest clusters approached older clusters. In woody clusters >30 yrs old ýSOM dynamics appear to be altered as the fractional percentages of the free light fraction ýý(250 µm) within the soils approximately doubles ýwith respect to surrounding grasslands, which is reflected in a strong shift in the amount ýand δ13C of respired CO2. Continuing research will investigate respiratory kinetics of soil ýphysical fractions and characterize the microbial community that develops during decay. ýThis work will have important implications for understanding how this globally relevant ývegetation shift will influence soil organic carbon storage. ý

  12. DESIGN OF DYADIC-INTEGER-COEFFICIENTS BASED BI-ORTHOGONAL WAVELET FILTERS FOR IMAGE SUPER-RESOLUTION USING SUB-PIXEL IMAGE REGISTRATION

    Directory of Open Access Journals (Sweden)

    P.B. Chopade

    2014-05-01

    Full Text Available This paper presents image super-resolution scheme based on sub-pixel image registration by the design of a specific class of dyadic-integer-coefficient based wavelet filters derived from the construction of a half-band polynomial. First, the integer-coefficient based half-band polynomial is designed by the splitting approach. Next, this designed half-band polynomial is factorized and assigned specific number of vanishing moments and roots to obtain the dyadic-integer coefficients low-pass analysis and synthesis filters. The possibility of these dyadic-integer coefficients based wavelet filters is explored in the field of image super-resolution using sub-pixel image registration. The two-resolution frames are registered at a specific shift from one another to restore the resolution lost by CCD array of camera. The discrete wavelet transform (DWT obtained from the designed coefficients is applied on these two low-resolution images to obtain the high resolution image. The developed approach is validated by comparing the quality metrics with existing filter banks.

  13. Trace element accumulation in woody plants of the Guadiamar Valley, SW Spain: A large-scale phytomanagement case study

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez, Maria T. [Instituto de Recursos Naturales y Agrobiologia, CSIC, P.O. Box 1052, E-41080 Seville (Spain)], E-mail: maitedn@irnase.csic.es; Maranon, Teodoro; Murillo, Jose M. [Instituto de Recursos Naturales y Agrobiologia, CSIC, P.O. Box 1052, E-41080 Seville (Spain); Schulin, Rainer; Robinson, Brett H. [Institute of Terrestrial Ecosystems, ETH Zuerich, Universitaetstrasse 16, CH-8092 Zurich (Switzerland)

    2008-03-15

    Phytomanagement employs vegetation and soil amendments to reduce the environmental risk posed by contaminated sites. We investigated the distribution of trace elements in soils and woody plants from a large phytomanaged site, the Guadiamar Valley (SW Spain), 7 years after a mine spill, which contaminated the area in 1998. At spill-affected sites, topsoils (0-25 cm) had elevated concentrations of As (129 mg kg{sup -1}), Bi (1.64 mg kg{sup -1}), Cd (1.44 mg kg{sup -1}), Cu (115 mg kg{sup -1}), Pb (210 mg kg{sup -1}), Sb (13.8 mg kg{sup -1}), Tl (1.17 mg kg{sup -1}) and Zn (457 mg kg{sup -1}). Trace element concentrations in the studied species were, on average, within the normal ranges for higher plants. An exception was white poplar (Populus alba), which accumulated Cd and Zn in leaves up to 3 and 410 mg kg{sup -1} respectively. We discuss the results with regard to the phytomanagement of trace element contaminated sites. - There is a low trace element transfer from contaminated soils to the aboveground parts of afforested woody plants under a semi-arid climate.

  14. Traits of riparian woody plants responding to hydrological and hydraulic conditions: a northern Swedish database.

    Science.gov (United States)

    Bejarano, María Dolores; Maroto, Judit; Nilsson, Christer; Aguiar, Francisca Constança

    2016-10-01

    The main goal of this study was to create a database that ultimately serves further studies on riparian vegetation and flow response guilds in the boreal region and on transferability of results across different regions. To achieve this aim, we compiled traits for all woody riparian species in northern Sweden which, directly or indirectly, underlie their responses to hydrological and hydraulic conditions, between October 2012 and April 2015. Consulted sources of information were diverse, ranging from scientific to informative and whose accuracy might or might not be verified. They were focused on particular or several traits and species from concrete areas to a worldwide perspective. Sources were characterized by different degrees of accessibility and showed a wide variety of descriptions, categorical and ordinal classifications, and numerical information for each trait. Our effort was to synthesize information for each trait from all sources into the common frame of our own database, following own defined criteria so that comparisons between species are congruent. Therefore, this data set is unique in that it comprehensively combines and homogenizes morphological, phenological, reproductive, and ecological data for 59 woody, riparian, boreal species and from 118 sources of information, that would otherwise be scattered and hardly available. © 2016 by the Ecological Society of America.

  15. Relationship of Course Woody Debris to Red-Cockaded Woodpecker Prey Diversity and Abundance

    Energy Technology Data Exchange (ETDEWEB)

    Horn, G.S.

    1999-09-03

    The abundance of diversity of prey commonly used by the red-cockaded woodpecker were monitored in experimental plots in which course woody debris was manipulated. In one treatment, all the woody debris over four inches was removed. In the second treatment, the natural amount of mortality remained intact. The overall diversity of prey was unaffected; however, wood roaches were significantly reduced by removal of woody debris. The latter suggests that intensive utilizations or harvesting practices may reduce foraging.

  16. Physically-based parameterization of spatially variable soil and vegetation using satellite multispectral data

    Science.gov (United States)

    Jasinski, Michael F.; Eagleson, Peter S.

    1989-01-01

    A stochastic-geometric landsurface reflectance model is formulated and tested for the parameterization of spatially variable vegetation and soil at subpixel scales using satellite multispectral images without ground truth. Landscapes are conceptualized as 3-D Lambertian reflecting surfaces consisting of plant canopies, represented by solid geometric figures, superposed on a flat soil background. A computer simulation program is developed to investigate image characteristics at various spatial aggregations representative of satellite observational scales, or pixels. The evolution of the shape and structure of the red-infrared space, or scattergram, of typical semivegetated scenes is investigated by sequentially introducing model variables into the simulation. The analytical moments of the total pixel reflectance, including the mean, variance, spatial covariance, and cross-spectral covariance, are derived in terms of the moments of the individual fractional cover and reflectance components. The moments are applied to the solution of the inverse problem: The estimation of subpixel landscape properties on a pixel-by-pixel basis, given only one multispectral image and limited assumptions on the structure of the landscape. The landsurface reflectance model and inversion technique are tested using actual aerial radiometric data collected over regularly spaced pecan trees, and using both aerial and LANDSAT Thematic Mapper data obtained over discontinuous, randomly spaced conifer canopies in a natural forested watershed. Different amounts of solar backscattered diffuse radiation are assumed and the sensitivity of the estimated landsurface parameters to those amounts is examined.

  17. Estimating urban vegetation fraction across 25 cities in pan-Pacific using Landsat time series data

    Science.gov (United States)

    Lu, Yuhao; Coops, Nicholas C.; Hermosilla, Txomin

    2017-04-01

    Urbanization globally is consistently reshaping the natural landscape to accommodate the growing human population. Urban vegetation plays a key role in moderating environmental impacts caused by urbanization and is critically important for local economic, social and cultural development. The differing patterns of human population growth, varying urban structures and development stages, results in highly varied spatial and temporal vegetation patterns particularly in the pan-Pacific region which has some of the fastest urbanization rates globally. Yet spatially-explicit temporal information on the amount and change of urban vegetation is rarely documented particularly in less developed nations. Remote sensing offers an exceptional data source and a unique perspective to map urban vegetation and change due to its consistency and ubiquitous nature. In this research, we assess the vegetation fractions of 25 cities across 12 pan-Pacific countries using annual gap-free Landsat surface reflectance products acquired from 1984 to 2012, using sub-pixel, spectral unmixing approaches. Vegetation change trends were then analyzed using Mann-Kendall statistics and Theil-Sen slope estimators. Unmixing results successfully mapped urban vegetation for pixels located in urban parks, forested mountainous regions, as well as agricultural land (correlation coefficient ranging from 0.66 to 0.77). The greatest vegetation loss from 1984 to 2012 was found in Shanghai, Tianjin, and Dalian in China. In contrast, cities including Vancouver (Canada) and Seattle (USA) showed stable vegetation trends through time. Using temporal trend analysis, our results suggest that it is possible to reduce noise and outliers caused by phenological changes particularly in cropland using dense new Landsat time series approaches. We conclude that simple yet effective approaches of unmixing Landsat time series data for assessing spatial and temporal changes of urban vegetation at regional scales can provide

  18. Effects of anabolic and catabolic nutrients on woody plant encroachment after long-term experimental fertilization in a South African savanna.

    Science.gov (United States)

    Mills, Anthony J; Milewski, Antoni V; Snyman, Dirk; Jordaan, Jorrie J

    2017-01-01

    The causes of the worldwide problem of encroachment of woody plants into grassy vegetation are elusive. The effects of soil nutrients on competition between herbaceous and woody plants in various landscapes are particularly poorly understood. A long-term experiment of 60 plots in a South African savanna, comprising annual applications of ammonium sulphate (146-1166 kg ha-1 yr-1) and superphosphate (233-466 kg ha-1 yr-1) over three decades, and subsequent passive protection over another three decades, during which indigenous trees encroached on different plots to extremely variable degrees, provided an opportunity to investigate relationships between soil properties and woody encroachment. All topsoils were analysed for pH, acidity, EC, water-dispersible clay, Na, Mg, K, Ca, P, S, C, N, NH4, NO3, B, Mn, Cu and Zn. Applications of ammonium sulphate (AS), but not superphosphate (SP), greatly constrained tree abundance relative to control plots. Differences between control plots and plots that had received maximal AS application were particularly marked (16.3 ± 5.7 versus 1.2 ± 0.8 trees per plot). Soil properties most affected by AS applications included pH (H2O) (control to maximal AS application: 6.4 ± 0.1 to 5.1 ± 0.2), pH (KCl) (5.5 ± 0.2 to 4.0 ± 0.1), acidity (0.7 ± 0.1 to 2.6 ± 0.3 cmol kg-1), acid saturation (8 ± 2 to 40 ± 5%), Mg (386 ± 25 to 143 ± 15 mg kg-1), Ca (1022 ± 180 to 322 ± 14 mg kg-1), Mn (314 ± 11 to 118 ± 9 mg kg-1), Cu (3.6 ± 0.3 to 2.3 ± 0.2 mg kg-1) and Zn (6.6 ± 0.4 to 3.7 ± 0.4 mg kg-1). Magnesium, B, Mn and Cu were identified using principal component analysis, boundary line analysis and Kruskal-Wallis rank sum tests as the nutrients most likely to be affecting tree abundance. The ratio Mn/Cu was most related to tree abundance across the experiment, supporting the hypothesis that competition between herbaceous and woody plants depends on the availability of anabolic relative to catabolic nutrients. These findings, based

  19. Vegetation assessment of forests of Pagan Island, Commonwealth of the Northern Mariana Islands

    Science.gov (United States)

    Pratt, Linda W.

    2011-01-01

    As part of the Marianas Expedition Wildlife Surveys-2010, the forest vegetation of the island of Pagan, Commonwealth of the Northern Mariana Islands (CNMI), was sampled with a series of systematic plots along 13 transects established for monitoring forest bird populations. Shrubland and grassland were also sampled in the northern half of the island. Data collected were woody plant density, tree diameter at breast height, woody plant density in height classes below 2 m, and ground cover measured with the point-intercept method. Coconut forests (Cocos nucifera) were generally found to have low native tree diversity, little regeneration of trees and shrubs in the forest understory, and little live ground cover. The sole exception was a coconut-dominated forest of the northeast side of the island that exhibited high native tree diversity and a large number of young native trees in the understory. Ironwood (Casuarina equisetifolia) forests on the northern half of the island were nearly monocultures with almost no trees other than ironwood in vegetation plots, few woody plants in the understory, and low ground cover dominated by native ferns. Mixed native forests of both northern and southern sections of the island had a diversity of native tree species in both the canopy and the sparse understory. Ground cover of native forests in the north had a mix of native and alien species, but that of the southern half of the island was dominated by native ferns and woody plants.

  20. Relative growth rates of three woody legumes: implications in the process of ecological invasion

    Directory of Open Access Journals (Sweden)

    J. A. Crisóstomo

    2007-03-01

    Full Text Available Acacia longifolia, an Australian leguminous tree, is one of the main invasive plant species in the coast of Portugal and a major threat to the native vegetation in the Reserva Natural das Dunas de São Jacinto. With the establishment of this exotic species, other native woody leguminous species such as Cytisus grandiflorus and Ulex europaeus have been displaced from their original areas. Several factors are involved in the process of biological invasion by exotic species. Plant physiology and development, characteristic of each species, can give certain advantages in the establishment and colonization of new areas. We tested if there are differences in the Relative Growth Rate (RGR of the exotic and native species because this could be relevant in the first stages of the invasion process. Our results showed that A. longifolia was the species with lowest RGR. Therefore, other factors apart from RGR might explain the invasion of coastal dunes by this species. We propose that A. longifolia might be a better competitor than the two native legumes and that this process might be mediated by the interaction with soil organisms.

  1. Variability in leaf morphology and photosynthetic responses of arctic woody shrubs to warming and shifts in snow induced thermal insulation

    Science.gov (United States)

    Flower, C. E.; Pereyra, G.; Welker, J. M.; Trumbore, S.; Gonzalez-Meler, M. A.

    2013-12-01

    Permafrost warming in the climate sensitive Arctic tundra has been linked to shifts in vegetation, from tussock dominated to tussock/shrub systems. This vegetation shift has the potential to not only impact the abiotic conditions, but also the energy balance and biogeochemical cycling of these systems; as plant assimilation, respiration, C allocation, and rooting depth may differ between plant functional groups. We assessed leaf morphology and constructed light response curves at ambient (400 ppm) and elevated (800 ppm) CO2 concentrations to assess photosynthetic responses of dwarf birch and diamond-leaf willow to a natural and induced simulated warming experiment at the Toolik Field Station in Alaska. Results indicate a positive correlation between summer soil thaw depth and leaf surface area indicating hydrological responses of both species. Additionally, leaf area was higher in warmed plots relative to non warmed plots in both the snow addition and the control treatments. Furthermore, we found that diamond-leaf willow exhibits elevated assimilation rates relative to dwarf birch. Both species exhibited similar photosynthetic responses to elevated CO2 increasing assimilation by ~34%. These responses highlight the forcing imposed by woody vegetation in arctic regions with the potential to increase net primary production in addition to positive feedbacks on winter snow depth, soil temperature, and moisture.

  2. A Framework for Quantifying the Impacts of Sub-Pixel Reflectance Variance and Covariance on Cloud Optical Thickness and Effective Radius Retrievals Based on the Bi-Spectral Method.

    Science.gov (United States)

    Zhang, Z; Werner, F.; Cho, H. -M.; Wind, Galina; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, Kerry

    2017-01-01

    The so-called bi-spectral method retrieves cloud optical thickness (t) and cloud droplet effective radius (re) simultaneously from a pair of cloud reflectance observations, one in a visible or near infrared (VIS/NIR) band and the other in a shortwave-infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved t and re. In this study, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the t and re retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the t and re retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VIS/NIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval.

  3. A framework for quantifying the impacts of sub-pixel reflectance variance and covariance on cloud optical thickness and effective radius retrievals based on the bi-spectral method

    Science.gov (United States)

    Zhang, Z.; Werner, F.; Cho, H.-M.; Wind, G.; Platnick, S.; Ackerman, A. S.; Di Girolamo, L.; Marshak, A.; Meyer, Kerry

    2017-02-01

    The so-called bi-spectral method retrieves cloud optical thickness (τ) and cloud droplet effective radius (re) simultaneously from a pair of cloud reflectance observations, one in a visible or near infrared (VIS/NIR) band and the other in a shortwave-infrared (SWIR) band. A cloudy pixel is usually assumed to be horizontally homogeneous in the retrieval. Ignoring sub-pixel variations of cloud reflectances can lead to a significant bias in the retrieved τ and re. In this study, we use the Taylor expansion of a two-variable function to understand and quantify the impacts of sub-pixel variances of VIS/NIR and SWIR cloud reflectances and their covariance on the τ and re retrievals. This framework takes into account the fact that the retrievals are determined by both VIS/NIR and SWIR band observations in a mutually dependent way. In comparison with previous studies, it provides a more comprehensive understanding of how sub-pixel cloud reflectance variations impact the τ and re retrievals based on the bi-spectral method. In particular, our framework provides a mathematical explanation of how the sub-pixel variation in VIS/NIR band influences the re retrieval and why it can sometimes outweigh the influence of variations in the SWIR band and dominate the error in re retrievals, leading to a potential contribution of positive bias to the re retrieval.

  4. Transfer of Virtual Water of Woody Forest Products from China

    Directory of Open Access Journals (Sweden)

    Kaisheng Luo

    2018-02-01

    Full Text Available Global freshwater resources are under increasing pressure. It is reported that international trade of water-intensive products (the so-called virtual water trade can be used to ease global water pressure. In spite of the significant amount of international trade of woody forest products, virtual water of woody forest products (VWWFP and the corresponding international trade are largely ignored. However, virtual water research has progressed steadily. This study maps VWWFP and statistically analyzes China’s official data for the period 1993–2014. The results show a rapid increase in the trend of VWWFP flow from China, reaching 7.61 × 1012 m3 or 3.48 times annual virtual water trade for agricultural products. The export and import volumes of China are respectively 1.27 × 1012 m3 and 6.34 × 1012 m3 for 1993–2014. China imported a total of 5.07 × 1012 m3 of VWWFP in 1993–2014 to lessen domestic water pressure, which is five times the annual water transfer via China’s South–North Water Transfer project. Asia and Europe account for the highest contribution (50.52% to China’s import. Other contributors include the Russian Federation (16.63%, Indonesia (13.45%, Canada (13.41%, the United States of America (9.60%, Brazil (7.23% and Malaysia (6.33%. China mainly exports VWWFP to Asia (47.68%, North America (23.24%, and Europe (20.01%. The countries which export the highest amount of VWWFP include the United States of America, Japan, Republic of Korea and Canada. Then the countries which import the highest amount of VWWFP include the Russian Federation, Canada, United States of America, and Brazil. The VWWFP flow study shows an obvious geographical distribution that is driven by proximity and traffic since transportation cost of woody forest products could be significant.

  5. Closed Loop Short Rotation Woody Biomass Energy Crops

    Energy Technology Data Exchange (ETDEWEB)

    Brower, Michael [CRC Development, LLC, Oakland, CA (United States)

    2012-09-30

    CRC Development LLC is pursuing commercialization of shrub willow crops to evaluate and confirm estimates of yield, harvesting, transportation and renewable energy conversion costs and to provide a diverse resource in its supply portfolio.The goal of Closed Loop Short Rotation Woody Biomass Energy Crops is supply expansion in Central New York to facilitate the commercialization of willow biomass crops as part of the mix of woody biomass feedstocks for bioenergy and bioproducts. CRC Development LLC established the first commercial willow biomass plantation acreage in North America was established on the Tug Hill in the spring of 2006 and expanded in 2007. This was the first 230- acres toward the goal of 10,000 regional acres. This project replaces some 2007-drought damaged acreage and installs a total of 630-acre new planting acres in order to demonstrate to regional agricultural producers and rural land-owners the economic vitality of closed loop short rotation woody biomass energy crops when deployed commercially in order to motivate new grower entry into the market-place. The willow biomass will directly help stabilize the fuel supply for the Lyonsdale Biomass facility, which produces 19 MWe of power and exports 15,000 pph of process steam to Burrows Paper. This project will also provide feedstock to The Biorefinery in New York for the manufacture of renewable, CO2-neutral liquid transportation fuels, chemicals and polymers. This project helps end dependency on imported fossil fuels, adds to region economic and environmental vitality and contributes to national security through improved energy independence.

  6. Sugars from woody tissue photosynthesis reduce xylem vulnerability to cavitation.

    Science.gov (United States)

    De Baerdemaeker, Niels J F; Salomón, Roberto Luis; De Roo, Linus; Steppe, Kathy

    2017-11-01

    Reassimilation of internal CO 2 via woody tissue photosynthesis has a substantial effect on tree carbon income and wood production. However, little is known about its role in xylem vulnerability to cavitation and its implications in drought-driven tree mortality. Young trees of Populus nigra were subjected to light exclusion at the branch and stem levels. After 40 d, measurements of xylem water potential, diameter variation and acoustic emission (AE) were performed in detached branches to obtain acoustic vulnerability curves to cavitation following bench-top dehydration. Acoustic vulnerability curves and derived AE 50 values (i.e. water potential at which 50% of cavitation-related acoustic emissions occur) differed significantly between light-excluded and control branches (AE 50,light-excluded  = -1.00 ± 0.13 MPa; AE 50,control  = -1.45 ± 0.09 MPa; P = 0.007) denoting higher vulnerability to cavitation in light-excluded trees. Woody tissue photosynthesis represents an alternative and immediate source of nonstructural carbohydrates (NSC) that confers lower xylem vulnerability to cavitation via sugar-mediated mechanisms. Embolism repair and xylem structural changes could not explain this observation as the amount of cumulative AE and basic wood density did not differ between treatments. We suggest that woody tissue assimilates might play a role in the synthesis of xylem surfactants for nanobubble stabilization under tension. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  7. Invasive alien woody plants of the northern Cape

    Directory of Open Access Journals (Sweden)

    L. Henderson

    1991-10-01

    Full Text Available The frequency and abundance of invasive alien woody plants were recorded along roadsides and at watercourse crossings in 31% (90/286 of the quarter degree squares in the study area. The survey yielded 23 species of which the most prominent invaders were Prosopis spp. The most prominent remaining species were: Opuntia ficus-indica, Nicotiana glauca and Melia azedarach. The greatest abundance and diversity of alien invader plants were recorded near human settlements. More than half of the total recorded species have invaded perennial riverbanks. The episodic Molopo and Kuruman Rivers have been invaded almost exclusively by  Prosopis spp., which in places have formed extensive stands.

  8. Invasive alien woody plants of the northern Cape

    Directory of Open Access Journals (Sweden)

    L. Henderson

    1991-12-01

    Full Text Available The frequency and abundance of invasive alien woody plants were recorded along roadsides and at watercourse crossings in 31% (90/286 of the quarter degree squares in the study area. The survey yielded 23 species of which the most prominent invaders were Prosopis spp. The most prominent remaining species were: Opuntia ficus-indica, Nicotiana glauca and Melia azedarach. The greatest abundance and diversity of alien invader plants were recorded near human settlements. More than half of the total recorded species have invaded perennial riverbanks. The episodic Molopo and Kuruman Rivers have been invaded almost exclusively by  Prosopis spp., which in places have formed extensive stands.

  9. Woody plant encroachment into grasslands: spatial patterns of functional group distribution and community development.

    Science.gov (United States)

    Liu, Feng; Archer, Steven R; Gelwick, Frances; Bai, Edith; Boutton, Thomas W; Wu, Xinyuan Ben

    2013-01-01

    Woody plant encroachment into grasslands has been globally widespread. The woody species invading grasslands represent a variety of contrasting plant functional groups and growth forms. Are some woody plant functional types (PFTs) better suited to invade grasslands than others? To what extent do local patterns of distribution and abundance of woody PFTs invading grasslands reflect intrinsic topoedaphic properties versus plant-induced changes in soil properties? We addressed these questions in the Southern Great Plains, United States at a subtropical grassland known to have been encroached upon by woody species over the past 50-100 years. A total of 20 woody species (9 tree-statured; 11 shrub-statured) were encountered along a transect extending from an upland into a playa basin. About half of the encroaching woody plants were potential N2-fixers (55% of species), but they contributed only 7% to 16 % of the total basal area. Most species and the PFTs they represent were ubiquitously distributed along the topoedaphic gradient, but with varying abundances. Overstory-understory comparisons suggest that while future species composition of these woody communities is likely to change, PFT composition is not. Canonical correspondence analysis (CCA) ordination and variance partitioning (Partial CCA) indicated that woody species and PFT composition in developing woody communities was primarily influenced by intrinsic landscape location variables (e.g., soil texture) and secondarily by plant-induced changes in soil organic carbon and total nitrogen content. The ubiquitous distribution of species and PFTs suggests that woody plants are generally well-suited to a broad range of grassland topoedaphic settings. However, here we only examined categorical and non-quantitative functional traits. Although intrinsic soil properties exerted more control over the floristics of grassland-to-woodland succession did plant modifications of soil carbon and nitrogen concentrations, the latter

  10. Evaluation of vegetation cover using the normalized difference vegetation index (NDVI

    Directory of Open Access Journals (Sweden)

    Gabriela Camargos Lima

    2013-08-01

    Full Text Available Soil loss by water erosion is the main cause of soil degradation in Brazil. However, erosion can be reduced by the presence of vegetation. The Normalized Difference Vegetation Index (NDVI makes it possible to identify the vegetative vigor of crops or natural vegetation which facilities the identification of areas with vegetation covers. This information is very important in identifying the phenomena which might be occurring in a particular area, especially those related to soil degradation by water erosion. Thus, the aim of this work was to assess the canopy cover by using NDVI, checking the image accuracy using the Coverage Index (CI based on the Stocking method, in the Sub-basin of Posses, which belongs to the Cantareira System, located in the Extrema municipality, Minas Gerais, Brazil. Landsat-5 TM images were used. The sub-basin of Posses was very altered in comparison to the surrounding areas. The NDVI technique proved to be a suitable tool to assess the uses that occur in the sub-basin of Posses, as validated by the Stocking methodology. The map derived from NDVI allowed the geographic distribution of different land uses to be observed and allowed for the identification of critical areas in relation to vegetation cover as well. This finding can be used to optimize efforts to recover and protect soil in areas with bare soil and degraded pasture, in order to reduce environmental degradation. The CI has not exceeded 40% for land use classes that occur in the majority of the sub-basin (91%, except in areas of woody vegetation.

  11. Lake Bathymetric Aquatic Vegetation

    Data.gov (United States)

    Minnesota Department of Natural Resources — Aquatic vegetation represented as polygon features, coded with vegetation type (emergent, submergent, etc.) and field survey date. Polygons were digitized from...

  12. A BAND SELECTION METHOD FOR SUB-PIXEL TARGET DETECTION IN HYPERSPECTRAL IMAGES BASED ON LABORATORY AND FIELD REFLECTANCE SPECTRAL COMPARISON

    Directory of Open Access Journals (Sweden)

    S. Sharifi hashjin

    2016-06-01

    Full Text Available In recent years, developing target detection algorithms has received growing interest in hyperspectral images. In comparison to the classification field, few studies have been done on dimension reduction or band selection for target detection in hyperspectral images. This study presents a simple method to remove bad bands from the images in a supervised manner for sub-pixel target detection. The proposed method is based on comparing field and laboratory spectra of the target of interest for detecting bad bands. For evaluation, the target detection blind test dataset is used in this study. Experimental results show that the proposed method can improve efficiency of the two well-known target detection methods, ACE and CEM.

  13. Integrating a Hive Triangle Pattern with Subpixel Analysis for Noncontact Measurement of Structural Dynamic Response by Using a Novel Image Processing Scheme

    Directory of Open Access Journals (Sweden)

    Yung-Chi Lu

    2014-01-01

    Full Text Available This work presents a digital image processing approach with a unique hive triangle pattern by integrating subpixel analysis for noncontact measurement of structural dynamic response data. Feasibility of proposed approach is demonstrated based on numerical simulation of a photography experiment. According to those results, the measured time-history displacement of simulated image correlates well with the numerical solution. A small three-story frame is then mounted on a small shaker table, and a linear variation differential transformation (LVDT is set on the second floor. Experimental results indicate that the relative error between data from LVDT and analyzed data from digital image correlation is below 0.007%, 0.0205 in terms of frequency and displacement, respectively. Additionally, the appropriate image block affects the estimation accuracy of the measurement system. Importantly, the proposed approach for evaluating pattern center and size is highly promising for use in assigning the adaptive block for a digital image correlation method.

  14. Woody Plant Invasion of Grassland: Storage and Turnover of Carbon in Soil Physical Fractions

    Science.gov (United States)

    Liao, J. D.; Boutton, T. W.; Jastrow, J. D.

    2003-12-01

    Woody plant encroachment is common in many grassland and savanna regions around the world. In the Rio Grande Plains of southern Texas, subtropical thorn woodlands dominated by C3 trees and shrubs (d13C = -27 o/oo) have largely replaced C4 grasslands (d13C = -14 o/oo) over the past 150 y. This vegetation change has resulted in increased soil organic carbon (SOC) storage. To elucidate mechanisms of SOC sequestration and turnover in this system, we separated soil organic matter into specific physical (size, density) fractions and determined natural d13C values of carbon in these fractions. Using a chronosequence approach, soils were collected from remnant grasslands (Time 0) and from woody plant stands ranging in age from 10-130 y. The free light-fraction (density less than 1 g/cm3) increased from 1 o/o of whole-soil weight in grasslands to 2-4 o/o of whole-soil weight in wooded landscape elements. The macroaggregate fraction (greater than 250 um) of soil in the 0-15 cm depth increment increased from less than 10 o/o of whole-soil dry weight in grasslands to more than 30 o/o of whole-soil weight in older woodlands. In contrast, the microaggregate fraction (53-250 um) decreased from 80 o/o of whole-soil weight in grasslands to 60 o/o of whole-soil weight after 80-130 y of woodland development. The decrease in microaggregates with increasing stand age likely reflects their incorporation into the macroaggregate fraction. Carbon contents (g C within a fraction per kg of whole soil) of all soil physical fractions (except free silt and clay) increased linearly with increasing woodland age, and were greatest in macroaggregates. Based on changes in natural C-13 abundance, mean residence times (1/k) for microaggregate carbon (326 y) were significantly greater than those for macroaggregate carbon (76 y), indicating that the older carbon associated with microaggregates is biochemically recalcitrant and/or physically protected. These results indicate that the interactions between

  15. Multiple pathways for woody plant establishment on floodplains at local to regional scales

    Science.gov (United States)

    Cooper, D.J.; Andersen, D.C.; Chimner, Rodney A.

    2003-01-01

    1. The structure and functioning of riverine ecosystems is dependent upon regional setting and the interplay of hydrologic regime and geomorphologic processes. We used a retrospective analysis to study recruitment along broad, alluvial valley segments (parks) and canyon segments of the unregulated Yampa River and the regulated Green River in the upper Colorado River basin, USA. We precisely aged 811 individuals of Populus deltoides ssp. wislizenii (native) and Tamarix ramosissima (exotic) from 182 wooded patches and determined the elevation and character of the germination surface for each. We used logistic regression to relate recruitment events (presence or absence of cohort) to five flow and two weather parameters.2. Woody plant establishment occurred via multiple pathways at patch, reach and segment scales. Recruitment occurred through establishment on (1) vertically accreting bars in the unregulated alluvial valley, (2) high alluvial floodplain surfaces during rare large flood events, (3) vertically accreting channel margin deposits in canyon pools and eddies, (4) vertically accreting intermittent/abandoned channels, (5) low elevation gravel bars and debris fans in canyons during multi-year droughts, and (6) bars and channels formed prior to flow regulation on the dammed river during controlled flood events.3. The Yampa River's peak flow was rarely included in models estimating the likelihood that recruitment would occur in any year. Flow variability and the interannual pattern of flows, rather than individual large floods, control most establishment.4. Regulation of the Green River flow since 1962 has had different effects on woody vegetation recruitment in canyons and valleys. The current regime mimics drought in a canyon setting, accelerating Tamarix invasion whereas in valleys the ongoing geomorphic adjustment of the channel, combined with reduced flow variability, has nearly eliminated Populus establishment.5. A single year's flow or a particular pattern

  16. Characteristics of African Savanna Biomes for Determining Woody Cover

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set includes the soil and vegetation characteristics, herbivore estimates, and precipitation measurement data for the 854 sites described and...

  17. Woody plants in dry sands : life history traits and population dynamics

    NARCIS (Netherlands)

    Li, S.|info:eu-repo/dai/nl/304849324

    2010-01-01

    Inland dune ecosystems are harsh environment for long-lived woody plants because of poor water and nutrient availability and frequent sand. As a result, long-lived woody plants have a high risk of being killed by sand movement or a long period of drought and this may occur even before they reach

  18. Interactions of woody biofuel feedstock production systems with water resources: considerations for sustainability

    Science.gov (United States)

    Carl C. Trettin; Devendra Amatya; Mark Coleman

    2008-01-01

    Water resources are important for the production of woody biofuel feedstocks. It is necessary to ensure that production systems do not adversely affect the quantity or quality of surface and ground water. The effects of woody biomass plantations on water resources are largely dependent on the prior land use and the management regime. Experience from both irrigated and...

  19. Hyper-temporal c-band SAR for baseline woody structural assessments in deciduous savannas

    CSIR Research Space (South Africa)

    Mathieu, Renaud SA

    2016-08-01

    Full Text Available ) in generating large-scale woody resources maps. Using airborne LiDAR as calibration, we investigated the relationships between hyper-temporal C-band ASAR data and woody structural parameters, namely total canopy cover (TCC) and total canopy volume (TCV), in a...

  20. Evaluation of techniques for determining the density of fine woody debris

    Science.gov (United States)

    Becky Fasth; Mark E. Harmon; Christopher W. Woodall; Jay. Sexton

    2010-01-01

    Evaluated various techniques for determining the density (i.e., bulk density) of fine woody debris during forest inventory activities. It was found that only experts in dead wood inventory may be able to identify fine woody debris stages of decay. Suggests various future research directions such as...

  1. Processing woody debris biomass for co-milling with pulverized coal

    Science.gov (United States)

    Dana Mitchell; Bob Rummer

    2007-01-01

    The USDA, Forest Service, Forest Products Lab funds several grants each year for the purpose of studying woody biomass utilization. One selected project proposed removing small diameter stems and unmerchantable woody material from National Forest lands and delivering it to a coal-fired power plant in Alabama for energy conversion. The Alabama Power Company...

  2. The combustion of sound and rotten coarse woody debris: a review

    Science.gov (United States)

    Joshua C. Hyde; Alistair M.S. Smith; Roger D. Ottmar; Ernesto C. Alvarado; Penelope. Morgan

    2011-01-01

    Coarse woody debris serves many functions in forest ecosystem processes and has important implications for fire management as it affects air quality, soil heating and carbon budgets when it combusts. There is relatively little research evaluating the physical properties relating to the combustion of this coarse woody debris with even less specifically addressing...

  3. Physical pretreatment – woody biomass size reduction – for forest biorefinery

    Science.gov (United States)

    J.Y. Zhu

    2011-01-01

    Physical pretreatment of woody biomass or wood size reduction is a prerequisite step for further chemical or biochemical processing in forest biorefinery. However, wood size reduction is very energy intensive which differentiates woody biomass from herbaceous biomass for biorefinery. This chapter discusses several critical issues related to wood size reduction: (1)...

  4. Fungal endophytes in woody roots of Douglas-fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa)

    Science.gov (United States)

    J. A. Hoff; Ned B. Klopfenstein; Geral I. McDonald; Jonalea R. Tonn; Mee-Sook Kim; Paul J. Zambino; Paul F. Hessburg; J. D. Rodgers; T. L. Peever; L. M. Carris

    2004-01-01

    The fungal community inhabiting large woody roots of healthy conifers has not been well documented. To provide more information about such communities, a survey was conducted using increment cores from the woody roots of symptomless Douglas-fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosa) growing in dry forests...

  5. Spatiotemporal soil and saprolite moisture dynamics across a semi-arid woody plant gradient

    Science.gov (United States)

    Woody plant cover has increased 10-fold over the last 140+ years in many parts of the semi-arid western USA. Woody plant cover can alter the timing and amount of plant available moisture in the soil and saprolite. To assess spatiotemporal subsurface moisture dynamics over two water years in a snow-d...

  6. Influence of fire on dead woody material in forests of California and southwestern Oregon

    Science.gov (United States)

    Carl N. Skinner

    2002-01-01

    The frequent occurrence of fire in most forested areas of California and southwestern Oregon before this century has been well established. Likewise, the importance of dead woody material to various wildlife species as snags and downed logs has been well documented. It is unlikely that much large woody material survived fire long enough to decompose fully in fire...

  7. 75 FR 76695 - Request for Proposals for 2011 Woody Biomass Utilization Grant Program

    Science.gov (United States)

    2010-12-09

    ... nationwide challenge of using low-value woody biomass material to create renewable energy. Goals of the grant... business risk to increase use of woody biomass from our nation's forestlands for renewable energy projects... energy technology, what other technologies were considered, why the recommended renewable energy...

  8. Characterization of fast pyrolysis products generated from several western USA woody species

    Science.gov (United States)

    Jacqueline M. Jarvis; Deborah S. Page-Dumroese; Nathaniel M. Anderson; Yuri Corilo; Ryan P. Rodgers

    2014-01-01

    Woody biomass has the potential to be utilized at an alternative fuel source through its pyrolytic conversion. Here, fast pyrolysis bio-oils derived from several western USA woody species are characterized by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to determine molecular-level composition. The...

  9. Response of Foliage of Young Loblolly Pine to Woody and Herbaceous Plant Control

    Science.gov (United States)

    Bruce R. Zutter; James H. Miller; H. Lee Allen; Shepard M. Zedake; M. Boyd Edwards; Ray A. Newbold

    1998-01-01

    Woody and herbaceous weeds have been shown to have a significant negative impact on survival and/or growth of planted loblolly pine (Pinus fueae L.) in the southeastern United States (Nelson et al. 1981, Zutter et al. 1986. Bacon and Zedaker 1987, Miller et al. 1987, 1991). Most research studies have focttsed on the effects of controlling only herbaceous, only woody,...

  10. Woody encroachment in northern Great Plains grasslands: Perceptions, actions, and needs

    Science.gov (United States)

    Symstad, Amy J.; Leis, Sherry A.

    2017-01-01

    The United States Northern Great Plains (NGP) has a high potential for landscape-scale conservation, but this grassland landscape is threatened by encroachment of woody species. We surveyed NGP land managers to identify patterns in, and illustrate a broad range of, individual managers' perceptions on (1) the threat of woody encroachment to grasslands they manage, and (2) what management practices they use that may influence woody encroachment in this region. In the 34 surveys returned, which came from predominantly public lands in the study area, 79% of responses reported moderate or substantial woody encroachment. Eastern redcedar (Juniperus virginiana) and Rocky Mountain juniper (Juniperus scopulorum) were the most problematic encroachers. Thirty-one survey respondents said that prescribed fire was used on the lands they manage, and 64% of these responses reported that controlling woody encroachment was a fire management objective. However, only 18% of survey respondents using prescribed fire were achieving their desired fire return interval. Most respondents reported using mechanical and/or chemical methods to control woody species. In contrast to evidence from the central and southern Great Plains, few survey respondents viewed grazing as affecting encroachment. Although the NGP public land managers we surveyed clearly recognize woody encroachment as a problem and are taking steps to address it, many feel that the rate of their management is not keeping pace with the rate of encroachment. Developing strategies for effective woody plant control in a variety of NGP management contexts requires filling ecological science gaps and overcoming societal barriers to using prescribed fire.

  11. Characterization of coarse woody debris across a 100 year chronosequence of upland oak-hickory forest

    Science.gov (United States)

    Travis W. Idol; Phillip E. Pope; Rebecca A. Figler; Felix Ponder Jr.

    1999-01-01

    Coarse woody debris is an important component influencing forest nutrient cycling and contributes to long-term soil productivity. The common practice of classifying coarse woody debris into different decomposition classes has seldom been related to the chemistry/biochemistry of the litter, which is the long term objective of our research. The objective of this...

  12. Multistage point relascope and randomized branch sampling for downed coarse woody debris estimation

    Science.gov (United States)

    Jeffrey H. Gove; Mark J. Ducey; Harry T. Valentine

    2002-01-01

    New sampling methods have recently been introduced that allow estimation of downed coarse woody debris using an angle gauge, or relascope. The theory behind these methods is based on sampling straight pieces of downed coarse woody debris. When pieces deviate from this ideal situation, auxillary methods must be employed. We describe a two-stage procedure where the...

  13. Influence of Bank Afforestation and Snag Angle-of-fall on Riparian Large Woody Debris Recruitment

    Science.gov (United States)

    Don C. Bragg; Jeffrey L. Kershner

    2002-01-01

    A riparian large woody debris (LWD) recruitment simulator (Coarse Woody Debris [CWD]) was used to test the impact of bank afforestation and snag fall direction on delivery trends. Combining all cumulative LWD recruitment across bank afforestation levels averaged 77.1 cubic meters per 100 meter reach (both banks forested) compared to 49.3 cubic meters per 100 meter...

  14. Modeling respiration from snags and coarse woody debris before and after an invasive gypsy moth disturbance

    Science.gov (United States)

    Heidi J. Renninger; Nicholas Carlo; Kenneth L. Clark; Karina V.R. Schäfer

    2014-01-01

    Although snags and coarse woody debris are a small component of ecosystem respiration, disturbances can significantly increase the mass and respiration from these carbon (C) pools. The objectives of this study were to (1) measure respiration rates of snags and coarse woody debris throughout the year in a forest previously defoliated by gypsy moths, (2) develop models...

  15. Interactions of woody biofuel feedstock production systems with water resources: Considerations for sustainability

    Science.gov (United States)

    Carl C. Trettin; Devendra Amatya; Mark Coleman

    2008-01-01

    Water resources are important for the production of woody biofuel feedstocks. It is necessary to ensure that production systems do not adversely affect the quantity or quality of surface and ground water. The effects of woody biomass plantations on water resources are largely dependent on the prior land use and the management regime. Experience from both irrigated and...

  16. Expected international demand for woody and herbaceous feedstock

    Energy Technology Data Exchange (ETDEWEB)

    Lamers, Patrick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Jacobson, Jacob [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mohammad, Roni [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wright, Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    The development of a U.S. bioenergy market and ultimately ‘bioeconomy’ has primarily been investigated with a national focus. Limited attention has been given to the potential impacts of international market developments. The goal of this project is to advance the current State of Technology of a single biorefinery to the global level providing quantitative estimates on how international markets may influence the domestic feedstock supply costs. The scope of the project is limited to feedstock that is currently available and new crops being developed to be used in a future U.S. bioeconomy including herbaceous residues (e.g., corn stover), woody biomass (e.g., pulpwood), and energy crops (e.g., switchgrass). The timeframe is set to the periods of 2022, 2030, and 2040 to align with current policy targets (e.g., the RFS2) and future updates of the Billion Ton data. This particular milestone delivers demand volumes for generic woody and herbaceous feedstocks for the main (net) importing regions along the above timeframes. The regional focus of the study is the European Union (EU), currently the largest demand region for U.S. pellets made from pulpwood and forest residues. The pellets are predominantly used in large-scale power plants (>5MWel) in the United Kingdom (UK), the Netherlands (NL), Belgium (BE), and Denmark (DK).

  17. Allelopathic Effects of Invasive Woody Plant Species in Hungary

    Directory of Open Access Journals (Sweden)

    CSISZÁR, Ágnes

    2009-01-01

    Full Text Available Allelopathy may play an important role in the invasion success of adventive plant species.The aim of this study was to determine the allelopathic potential of invasive woody plant species occurringin Hungary. Juglone index of fourteen invasive woody plant species in Hungary was determined by themethod of Szabó (1997, comparing the effects of juglone and substance extracted of plant species withunknown allelopathic potential on the germination rate, shoot length and rooth length of white mustard(Sinapis alba L. used as receiver species. Results have proven a more or less expressed allelopathicpotential in case of all species. The juglone index at higher concentration extracts (5 g dry plant materialextracted with 100 ml distilled water of almost every studied species approaches to 1 or is above 1, thismeans the effect of the extracts is similar to juglone or surpasses it. In terms of juglone index, theallelopathic potential of false indigo (Amorpha fruticosa L., tree-of-heaven (Ailanthus altissima (Mill.Swingle and hackberry (Celtis occidentalis L. were the highest. Besides these species the treatment withthe extracts of black walnut (Juglans nigra L., black cherry (Prunus serotina Ehrh. and green ash(Fraxinus pennsylvanica MARSH. var. subintegerrima (Vahl Fern. reduced extremely significantly thegermination rate, shoot and root length, compared to the control.

  18. Flowering of Woody Bamboo in Tissue Culture Systems

    Directory of Open Access Journals (Sweden)

    Jin-Ling Yuan

    2017-09-01

    Full Text Available Flowering and subsequent seed set are not only normal activities in the life of most plants, but constitute the very reason for their existence. Woody bamboos can take a long time to flower, even over 100 years. This makes it difficult to breed bamboo, since flowering time cannot be predicted and passing through each generation takes too long. Another unique characteristic of woody bamboo is that a bamboo stand will often flower synchronously, both disrupting the supply chain within the bamboo industry and affecting local ecology. Therefore, an understanding of the mechanism that initiates bamboo flowering is important not only for biology research, but also for the bamboo industry. Induction of flowering in vitro is an effective way to both shorten the flowering period and control the flowering time, and has been shown for several species of bamboo. The use of controlled tissue culture systems allows investigation into the mechanism of bamboo flowering and facilitates selective breeding. Here, after a brief introduction of flowering in bamboo, we review the research on in vitro flowering of bamboo, including our current understanding of the effects of plant growth regulators and medium components on flower induction and how in vitro bamboo flowers can be used in research.

  19. Employing lidar to detail vegetation canopy architecture for prediction of aeolian transport

    Science.gov (United States)

    Sankey, Joel B.; Law, Darin J.; Breshears, David D.; Munson, Seth M.; Webb, Robert H.

    2013-05-01

    diverse and fundamental effects that aeolian processes have on the biosphere and geosphere are commonly generated by horizontal sediment transport at the land surface. However, predicting horizontal sediment transport depends on vegetation architecture, which is difficult to quantify in a rapid but accurate manner. We demonstrate an approach to measure vegetation canopy architecture at high resolution using lidar along a gradient of dryland sites ranging from 2% to 73% woody plant canopy cover. Lidar-derived canopy height, distance (gaps) between vegetation elements (e.g., trunks, limbs, leaves), and the distribution of gaps scaled by vegetation height were correlated with canopy cover and highlight potentially improved horizontal dust flux estimation than with cover alone. Employing lidar to estimate detailed vegetation canopy architecture offers promise for improved predictions of horizontal sediment transport across heterogeneous plant assemblages.

  20. On the Assessment of the CO2 Mitigation Potential of Woody Biomass

    Directory of Open Access Journals (Sweden)

    Víctor Codina Gironès

    2018-01-01

    Full Text Available Woody biomass, a renewable energy resource, accumulates solar energy in form of carbon hydrates produced from atmospheric CO2 and H2O. It is, therefore, a means of CO2 mitigation for society as long as the biogenic carbon released to the atmosphere when delivering its energy content by oxidation can be accumulated again during growth of new woody biomass. Even when considering the complete life cycle, usually, only a small amount of fossil CO2 is emitted. However, woody biomass availability is limited by land requirement and, therefore, it is important to maximize its CO2 mitigation potential in the energy system. In this study, we consider woody biomass not only as a source of renewable energy but also as a source of carbon for seasonal storage of solar electricity. A first analysis is carried out based on the mitigation effect of woody biomass usage pathways, which is the avoided fossil CO2 emissions obtained by using one unit of woody biomass to provide energy services, as alternative to fossil fuels. Results show that woody biomass usage pathways can achieve up to 9.55 times the mitigation effect obtained through combustion of woody biomass, which is taken as a reference. Applying energy system modeling and multi-objective optimization techniques, the role of woody biomass technological choices in the energy transition is then analyzed at a country scale. The analysis is applied to Switzerland, demonstrating that the use of woody biomass in gasification–methanation systems, coupled with electrolysers and combined with an intensive deployment of PV panels and efficient technologies, could reduce the natural gas imports to zero. Electrolysers are used to boost synthetic natural gas production by hydrogen injection into the methanation reaction. The hydrogen used is produced when there is excess of solar electricity. The efficient technologies, such as heat pumps and battery electric vehicles, allow increasing the overall efficiency of the

  1. Nutrient concentrations in coarse and fine woody debris of Populus tremuloides Michx.-dominated forests, northern Minnesota, USA

    Science.gov (United States)

    Klockow, Paul A.; D'Amato, Anthony W.; Bradford, John B.; Fraver, Shawn

    2014-01-01

    Contemporary forest harvesting practices, specifically harvesting woody biomass as a source of bioenergy feedstock, may remove more woody debris from a site than conventional harvesting. Woody debris, particularly smaller diameter woody debris, plays a key role in maintaining ecosystem nutrient stores following disturbance. Understanding nutrient concentrations within woody debris is necessary for assessing the long-term nutrient balance consequences of altered woody debris retention, particularly in forests slated for use as bioenergy feedstocks. Nutrient concentrations in downed woody debris of various sizes, decay classes, and species were characterized within one such forest type, Populus tremuloides Michx.-dominated forests of northern Minnesota, USA. Nutrient concentrations differed significantly between size and decay classes and generally increased as decay progressed. Fine woody debris (≤ 7.5 cm diameter) had higher nutrient concentrations than coarse woody debris (> 7.5 cm diameter) for all nutrients examined except Na and Mn, and nutrient concentrations varied among species. Concentrations of N, Mn, Al, Fe, and Zn in coarse woody debris increased between one and three orders of magnitude, while K decreased by an order of magnitude with progressing decay. The variations in nutrient concentrations observed here underscore the complexity of woody debris nutrient stores in forested ecosystems and suggest that retaining fine woody debris at harvest may provide a potentially important source of nutrients following intensive removals of bioenergy feedstocks.

  2. Climatic regions as an indicator of forest coarse and fine woody debris carbon stocks in the United States

    Science.gov (United States)

    Christopher W. Woodall; Greg C. Liknes

    2008-01-01

    Coarse and fine woody debris are substantial forest ecosystem carbon stocks; however, there is a lack of understanding how these detrital carbon stocks vary across forested landscapes. Because forest woody detritus production and decay rates may partially depend on climatic conditions, the accumulation of coarse and fine woody debris carbon stocks in forests may be...

  3. Regional assessment of woody biomass physical availability as an energy feedstock for combined combustion in the US northern region

    Science.gov (United States)

    Michael E. Goerndt; Francisco X. Aguilar; Patrick Miles; Stephen Shifley; Nianfu Song; Hank Stelzer

    2012-01-01

    Woody biomass is a renewable energy feedstock with the potential to reduce current use of nonrenewable fossil fuels. We estimated the physical availability of woody biomass for cocombustion at coal-fired electricity plants in the 20-state US northern region. First, we estimated the total amount of woody biomass needed to replace total annual coal-based electricity...

  4. miRNA control of vegetative phase change in trees.

    Science.gov (United States)

    Wang, Jia-Wei; Park, Mee Yeon; Wang, Ling-Jian; Koo, Yeonjong; Chen, Xiao-Ya; Weigel, Detlef; Poethig, R Scott

    2011-02-01

    After germination, plants enter juvenile vegetative phase and then transition to an adult vegetative phase before producing reproductive structures. The character and timing of the juvenile-to-adult transition vary widely between species. In annual plants, this transition occurs soon after germination and usually involves relatively minor morphological changes, whereas in trees and other perennial woody plants it occurs after months or years and can involve major changes in shoot architecture. Whether this transition is controlled by the same mechanism in annual and perennial plants is unknown. In the annual forb Arabidopsis thaliana and in maize (Zea mays), vegetative phase change is controlled by the sequential activity of microRNAs miR156 and miR172. miR156 is highly abundant in seedlings and decreases during the juvenile-to-adult transition, while miR172 has an opposite expression pattern. We observed similar changes in the expression of these genes in woody species with highly differentiated, well-characterized juvenile and adult phases (Acacia confusa, Acacia colei, Eucalyptus globulus, Hedera helix, Quercus acutissima), as well as in the tree Populus x canadensis, where vegetative phase change is marked by relatively minor changes in leaf morphology and internode length. Overexpression of miR156 in transgenic P. x canadensis reduced the expression of miR156-targeted SPL genes and miR172, and it drastically prolonged the juvenile phase. Our results indicate that miR156 is an evolutionarily conserved regulator of vegetative phase change in both annual herbaceous plants and perennial trees.

  5. miRNA control of vegetative phase change in trees.

    Directory of Open Access Journals (Sweden)

    Jia-Wei Wang

    2011-02-01

    Full Text Available After germination, plants enter juvenile vegetative phase and then transition to an adult vegetative phase before producing reproductive structures. The character and timing of the juvenile-to-adult transition vary widely between species. In annual plants, this transition occurs soon after germination and usually involves relatively minor morphological changes, whereas in trees and other perennial woody plants it occurs after months or years and can involve major changes in shoot architecture. Whether this transition is controlled by the same mechanism in annual and perennial plants is unknown. In the annual forb Arabidopsis thaliana and in maize (Zea mays, vegetative phase change is controlled by the sequential activity of microRNAs miR156 and miR172. miR156 is highly abundant in seedlings and decreases during the juvenile-to-adult transition, while miR172 has an opposite expression pattern. We observed similar changes in the expression of these genes in woody species with highly differentiated, well-characterized juvenile and adult phases (Acacia confusa, Acacia colei, Eucalyptus globulus, Hedera helix, Quercus acutissima, as well as in the tree Populus x canadensis, where vegetative phase change is marked by relatively minor changes in leaf morphology and internode length. Overexpression of miR156 in transgenic P. x canadensis reduced the expression of miR156-targeted SPL genes and miR172, and it drastically prolonged the juvenile phase. Our results indicate that miR156 is an evolutionarily conserved regulator of vegetative phase change in both annual herbaceous plants and perennial trees.

  6. SURVEY OF WOODY FLORA AND FAUNA OF THE BAHIR DAR ...

    African Journals Online (AJOL)

    Abstract: The aim of this project was to survey the flora and fauna of the main campus of. Bahir Dar Vniversity. It was necessary because the university campus is relatively well rehabilitated and it is very important that the composition of the vegetation, the regeneration capacity of the vegetation and the importance of the tree ...

  7. Analysis of Vegetation Index Variations and the Asian Monsoon Climate

    Science.gov (United States)

    Shen, Sunhung; Leptoukh, Gregory G.; Gerasimov, Irina

    2012-01-01

    Vegetation growth depends on local climate. Significant anthropogenic land cover and land use change activities over Asia have changed vegetation distribution as well. On the other hand, vegetation is one of the important land surface variables that influence the Asian Monsoon variability through controlling atmospheric energy and water vapor conditions. In this presentation, the mean and variations of vegetation index of last decade at regional scale resolution (5km and higher) from MODIS have been analyzed. Results indicate that the vegetation index has been reduced significantly during last decade over fast urbanization areas in east China, such as Yangtze River Delta, where local surface temperatures were increased significantly in term of urban heat Island. The relationship between vegetation Index and climate (surface temperature, precipitation) over a grassland in northern Asia and over a woody savannas in southeast Asia are studied. In supporting Monsoon Asian Integrated Regional Study (MAIRS) program, the data in this study have been integrated into Giovanni, the online visualization and analysis system at NASA GES DISC. Most images in this presentation are generated from Giovanni system.

  8. Vegetative Regeneration Capacities of Five Ornamental Plant Invaders After Shredding

    Science.gov (United States)

    Monty, Arnaud; Eugène, Marie; Mahy, Grégory

    2015-02-01

    Vegetation management often involves shredding to dispose of cut plant material or to destroy the vegetation itself. In the case of invasive plants, this can represent an environmental risk if the shredded material exhibits vegetative regeneration capacities. We tested the effect of shredding on aboveground and below-ground vegetative material of five ornamental widespread invaders in Western Europe that are likely to be managed by cutting and shredding techniques: Buddleja davidii (butterfly bush, Scrophulariaceae), Fallopia japonica (Japanese knotweed, Polygonaceae), Spiraea × billardii Hérincq (Billard's bridewort, Rosaceae), Solidago gigantea (giant goldenrod, Asteraceae), and Rhus typhina L. (staghorn sumac, Anacardiaceae). We looked at signs of vegetative regeneration and biomass production, and analyzed the data with respect to the season of plant cutting (spring vs summer), the type of plant material (aboveground vs below-ground), and the shredding treatment (shredded vs control). All species were capable of vegetative regeneration, especially the below-ground material. We found differences among species, but the regeneration potential was generally still present after shredding despite a reduction of growth rates. Although it should not be excluded in all cases (e.g., destruction of giant goldenrod and staghorn sumac aboveground material), the use of a shredder to destroy woody alien plant material cannot be considered as a general management option without significant environmental risk.

  9. Non-structural carbohydrates in woody plants compared among laboratories.

    Science.gov (United States)

    Quentin, Audrey G; Pinkard, Elizabeth A; Ryan, Michael G; Tissue, David T; Baggett, L Scott; Adams, Henry D; Maillard, Pascale; Marchand, Jacqueline; Landhäusser, Simon M; Lacointe, André; Gibon, Yves; Anderegg, William R L; Asao, Shinichi; Atkin, Owen K; Bonhomme, Marc; Claye, Caroline; Chow, Pak S; Clément-Vidal, Anne; Davies, Noel W; Dickman, L Turin; Dumbur, Rita; Ellsworth, David S; Falk, Kristen; Galiano, Lucía; Grünzweig, José M; Hartmann, Henrik; Hoch, Günter; Hood, Sharon; Jones, Joanna E; Koike, Takayoshi; Kuhlmann, Iris; Lloret, Francisco; Maestro, Melchor; Mansfield, Shawn D; Martínez-Vilalta, Jordi; Maucourt, Mickael; McDowell, Nathan G; Moing, Annick; Muller, Bertrand; Nebauer, Sergio G; Niinemets, Ülo; Palacio, Sara; Piper, Frida; Raveh, Eran; Richter, Andreas; Rolland, Gaëlle; Rosas, Teresa; Saint Joanis, Brigitte; Sala, Anna; Smith, Renee A; Sterck, Frank; Stinziano, Joseph R; Tobias, Mari; Unda, Faride; Watanabe, Makoto; Way, Danielle A; Weerasinghe, Lasantha K; Wild, Birgit; Wiley, Erin; Woodruff, David R

    2015-11-01

    Non-structural carbohydrates (NSC) in plant tissue are frequently quantified to make inferences about plant responses to environmental conditions. Laboratories publishing estimates of NSC of woody plants use many different methods to evaluate NSC. We asked whether NSC estimates in the recent literature could be quantitatively compared among studies. We also asked whether any differences among laboratories were related to the extraction and quantification methods used to determine starch and sugar concentrations. These questions were addressed by sending sub-samples collected from five woody plant tissues, which varied in NSC content and chemical composition, to 29 laboratories. Each laboratory analyzed the samples with their laboratory-specific protocols, based on recent publications, to determine concentrations of soluble sugars, starch and their sum, total NSC. Laboratory estimates differed substantially for all samples. For example, estimates for Eucalyptus globulus leaves (EGL) varied from 23 to 116 (mean = 56) mg g(-1) for soluble sugars, 6-533 (mean = 94) mg g(-1) for starch and 53-649 (mean = 153) mg g(-1) for total NSC. Mixed model analysis of variance showed that much of the variability among laboratories was unrelated to the categories we used for extraction and quantification methods (method category R(2) = 0.05-0.12 for soluble sugars, 0.10-0.33 for starch and 0.01-0.09 for total NSC). For EGL, the difference between the highest and lowest least squares means for categories in the mixed model analysis was 33 mg g(-1) for total NSC, compared with the range of laboratory estimates of 596 mg g(-1). Laboratories were reasonably consistent in their ranks of estimates among tissues for starch (r = 0.41-0.91), but less so for total NSC (r = 0.45-0.84) and soluble sugars (r = 0.11-0.83). Our results show that NSC estimates for woody plant tissues cannot be compared among laboratories. The relative changes in NSC between treatments measured within a laboratory

  10. Riparian Vegetation Encroachment Ratios in rivers below large Dams

    Science.gov (United States)

    Garcia de Jalón, Diego; Martínez-Fernández, Vanesa; González del Tánago, Marta

    2017-04-01

    Large Dams and reservoirs change the natural flow regime and consequently cause many alterations in riparian vegetation dynamics which may be assessed at different spatial and temporal scales. In Mediterranean regions flow regulation is frequently associated with irrigation. Regulated rivers with this purpose very often show reduced discharges during the wet season when the reservoir is being filled and increased discharges during the dry season when irrigation takes place. This type of regulation frequently promotes riparian vegetation growth as soil moisture levels are increased during summer when a natural drought would otherwise limit its growth. Additionally, flow regulation by large dams promotes the aging of late seral riparian vegetation reducing the frequency of flood disturbance and consequently, the potential recruitment of pioneer species. In this work we study the response of woody riparian vegetation to flow regulation by large dams in four rivers from Central Spain: Jarama, Manzanares, Guadalix and Alberche. The aim is to quantify the annual vegetation encroachment ratios and to develop a model to understand the main controlling factors, such as floodplain and channel traits; flow regulation intensity; type of regulation; present vegetation canopy; distance to the dam; and time since dam commissioning. A temporal comparison using aerial photographs from 1956, 1966, 1972, 1991, 2011 and 2014 was done in thirteen river reaches downstream from large dams, to evaluate their morphological evolution.. Floodplain dimensions and channel and riparian vegetation changes were assessed by comparing different pre-dam and post-dam conditions. Recent coloured photographs with 0.5 m spatial resolution and older black-and-white photographs at 1:33 000 spatial scale were supplied by the National Geographic Institute of Spain (www.ign.es) and the Statistical Institute (www.madrid.org/nomecalles/Inicio.icm) from Madrid Community. Similar visual scales were used to cope

  11. Organic carbon isotope and molecular fossil records of vegetation evolution in central Loess Plateau since 450 kyr

    OpenAIRE

    Zhou, Bin; Wali, Guzalnur; Peterse, Francien; Bird, Michael I.

    2016-01-01

    Significant uncertainties remain regarding the temporal evolution of natural vegetation during the Quaternary, and drivers of past vegetation change, on the Chinese Loess Plateau (CLP). This study presents analyses of total organic carbon isotopic composition (TOC) and n-alkane ratios (C31/C27) from the Lingtai loess-palaeosol sequence on the central CLP over the last 450 kyr. The results demonstrate that the vegetation in this region comprised a mix of C3 and C4 plants of herb and woody grow...

  12. Spontaneous changes a basis for new ornamental woody plant cultivars

    Directory of Open Access Journals (Sweden)

    Đukić Matilda

    2006-01-01

    Full Text Available In nursery stock production of some ornamental woody plants the appearance of spontaneous variability was identified in the form of atypical pigmentation of leaves (albinism, variegated, red colored, leaves shape (jaggy and dwarfs. Mutated plants with variegated leaves were observed among hybrid plane (Platanus x acerifolia (Ait. Willd., Siberian elm (Ulmus pumila L., laurel cherry (Prunus laurocerasus L. and Lawson false-cypress (Chamaecyparis lawsoniana (Murr. Parl. Seedlings. The type of variegation and frequency were analyzed. Among plane tree and Siberian elm seedlings there were observed red colored leaves. Atypical, jaggy shaped leaves were found among laurel cherry seedlings. Dwarf growth was identified at Siberian elm and birch (Betula pendula Roth. where also found fruits at one year seedling. There were not significant differences in some morphological and physiological properties in plane tree seedlings with various pigmented leaves. .

  13. Invasive alien woody plants of the Orange Free State

    Directory of Open Access Journals (Sweden)

    L. Henderson

    1991-09-01

    Full Text Available The frequency and abundance of invasive alien woody plants were recorded along roadsides and at watercourse crossings in 66% (151/230 of the quarter degree squares in the study area. The survey yielded 64 species of which the most prominent (in order of prominence in streambank habitats were:  Salix babylonica, Populus x  canescens, Acacia dealbata and  Salix fragilis (fide R.D. Meikle pers. comm . The most prominent species (in order of prominence in roadside and veld habitats were:  Opunlia ficus-indica, Prunus persica, Eucalyptus spp..  Rosa eglanteria, Pyracantha angustifolia and Acacia dealbata.Little invasion was recorded for most of the province. The greatest intensity of invasion was recorded along the perennial rivers and rocky hillsides in the moist grassland of the eastern mountain region bordering on Lesotho and Natal.

  14. Methods for Rapid Screening in Woody Plant Herbicide Development

    Directory of Open Access Journals (Sweden)

    William Stanley

    2014-07-01

    Full Text Available Methods for woody plant herbicide screening were assayed with the goal of reducing resources and time required to conduct preliminary screenings for new products. Rapid screening methods tested included greenhouse seedling screening, germinal screening, and seed screening. Triclopyr and eight experimental herbicides from Dow AgroSciences (DAS 313, 402, 534, 548, 602, 729, 779, and 896 were tested on black locust, loblolly pine, red maple, sweetgum, and water oak. Screening results detected differences in herbicide and species in all experiments in much less time (days to weeks than traditional field screenings and consumed significantly less resources (<500 mg acid equivalent per herbicide per screening. Using regression analysis, various rapid screening methods were linked into a system capable of rapidly and inexpensively assessing herbicide efficacy and spectrum of activity. Implementation of such a system could streamline early-stage herbicide development leading to field trials, potentially freeing resources for use in development of beneficial new herbicide products.

  15. Chemical Characteristics of Six Woody Species for Alley Cropping

    Directory of Open Access Journals (Sweden)

    Mosango, M.

    1999-01-01

    Full Text Available Leaves of six woody species (Leguminosae for alley cropping have been chemically analysed in order to evaluate their potentiality in the restoration of soil fertility. These species are : Acacia mangium, Cajanus cajan, Flemingia grahamiana, F. macrophylla, Leucaena leucocephala and Sesbania sesban. Nitrogen, carbon, cellulose, hemicellulose, lignin, active fraction and ash contents were determined as well as C/N and L/N ratios. AH these species appear to be rich in N and C. Fiber contents (cellulose, hemicellulose and lignin are globally low but variable from one species to another. C/N and L/N ratios are globally low. Among these species, Leucaena leucocephala and Senna spectabilis show the lowest C/N and LIN ratios. Such low values of C/N and L/N are normally found in species with rapid decomposition of organic matter.

  16. Invasive alien woody plants of the Orange Free State

    Directory of Open Access Journals (Sweden)

    L. Henderson

    1991-12-01

    Full Text Available The frequency and abundance of invasive alien woody plants were recorded along roadsides and at watercourse crossings in 66% (151/230 of the quarter degree squares in the study area. The survey yielded 64 species of which the most prominent (in order of prominence in streambank habitats were:  Salix babylonica, Populus x  canescens, Acacia dealbata and  Salix fragilis (fide R.D. Meikle pers. comm . The most prominent species (in order of prominence in roadside and veld habitats were:  Opunlia ficus-indica, Prunus persica, Eucalyptus spp..  Rosa eglanteria, Pyracantha angustifolia and Acacia dealbata.Little invasion was recorded for most of the province. The greatest intensity of invasion was recorded along the perennial rivers and rocky hillsides in the moist grassland of the eastern mountain region bordering on Lesotho and Natal.

  17. Effect of downed woody debris on small mammal anti-predator behavior.

    Energy Technology Data Exchange (ETDEWEB)

    Hinkleman, Travis, M.; Orrock, John, L.; Loeb, Susan, C.

    2011-10-01

    Anti-predator behavior can affect prey growth, reproduction, survival, and generate emergent effects in food webs. Small mammals often lower the cost of predation by altering their behavior in response to shrubs,but the importance of other microhabitat features, such as downed woody debris, for anti-predator behavior is unknown. We used givingup densities to quantify the degree to which downed woody debris alters perceived predation risk by small mammals in southeastern pineforests. We placed 14 foraging trays next to large downed woody debris,shrubs, and in open areas for 12 consecutive nights. Moon illumination, a common indicator of predation risk, led to a similar reduction in small mammal foraging in all three microhabitats (open, downed woody debris,and shrub). Small mammals perceived open microhabitats as riskier than shrub microhabitats, with downed woody debris habitats perceived as being of intermediate risk between shrub and open microhabitats. Despite the presumed benefits of the protective cover of downed woody debris, small mammals may perceive downed woody debris as a relatively risky foraging site in southeastern pine forests where the high diversity and abundance of rodent-eating snakes may provide a primary predatory threat.

  18. Substrates Preparation from Woody Tropical Waste Biomass for Biohydrogen Production

    Directory of Open Access Journals (Sweden)

    Dwi Susilaningsih

    2010-10-01

    Full Text Available Addressing to the global warming problem, energy crisis and pollution, hydrogen production by micro-organisms using biotechnological approach should be considered, since it fulfils the recent society requirement to safely produce, renewable and environmental friendly energy. Hydrogen is one of the most promising green energy sources, because it is easily converted to electricity and cleanly combustible. There are three types of micro-organisms for hydrogen production, the first is cyanobacteria through the photosynthesis process, the second is anaerobic bacteria, which use organic substances as electron donor and energy and convert them to hydrogen, the third is photosynthetic bacteria, somewhat between photosynthetic and anaerobic bacteria, which are capable of converting the organic substances to hydrogen at a fairly high rate. We propose to use the abundant waste biomasses in Indonesia for hydrogen production by the microbial system. Our focus research is the production of hydrogen from waste biomasses by two-stage fermentation systems, which combine the conversion process of monomer biomasses to lactic acid by Lactobacillus sp. and the conversion process of lactic acid to hydrogen by photosynthetic bacteria. In this research, two kind substrates preparation were apply for woody waste biomass such as chemical hydrolysis and biological methods with several treatments. The results of the substrate preparation state showed that hydrolyses process of biomasses using strong acid are yielded total sugar about 70-90% of previous original content. Moreover, hydrolyses process using weak/diluted acid are yielded total sugar about 4-30% of original sugar. Furthermore, the biological treatments of degradation of woody waste biomasses are yielded total sugar about 0-10% (by single culture and 10-50% (by consortium. Those hydrolysates substrates will use for fermentation two stages of lactate fermentation and conversion by photosynthetic bacteria in order

  19. BAAD: a Biomass And Allometry Database for woody plants

    Energy Technology Data Exchange (ETDEWEB)

    Falster, Daniel; Duursma, Remko; Ishihara, Masae; Barneche, Diego; Fitzjohn, Richard; Varhammar, Angelica; Aiba, Masahiro; Ando, M.; Anten, Niels; Aspinwall, Michael J.; Baltzer, Jennifer; Baraloto, Christopher; Battaglia, Michael; Battles, John; Bond-Lamberty, Benjamin; van Breugel, Michiel; Camac, James; Claveau, Yves; Coll Mir, Llus; Dannoura, Dannoura; Delagrange, Sylvain; Domec, Jean-Cristophe; Fatemi, Farrah; Feng, Wang; Gargaglione, Veronica; Goto, Yoshiaki; Hagihara, Akio; Hall, Jefferson S.; Hamilton, Steve; Harja, Degi; Hiura, Tsutom; Holdaway, Robert; Hutley, L. B.; Ichie, Tomoaki; Jokela, Eric; Kantola, Anu; Kelly, Jeffery W.; Kenzo, Tanaka; King, David A.; Kloeppel, Brian; Kohyama, Takashi; Komiyama, Akira; Laclau, Jean-Paul; Lusk, Christopher; Maguire, Doug; le Maire, Guerric; Makela, Annikki; Markesteijn, Lars; Marshall, John; McCulloh, Kate; Miyata, Itsuo; Mokany, Karen; Mori, Shigeta; Myster, Randall; Nagano, Masahiro; Naidu, Shawna; Nouvellon, Yann; O' Grady, Anthony; O' Hara, Kevin; Ohtsuka, Toshiyuki; Osada, Noriyuki; Osunkoya, Olusegun O.; Luis Peri, Pablo; Petritan, Mary; Poorter, Lourens; Portsmuth, Angelika; Potvin, Catherine; Ransijn, Johannes; Reid, Douglas; Ribeiro, Sabina C.; Roberts, Scott; Rodriguez, Rolando; Saldana-Acosta, Angela; Santa-Regina, Ignacio; Sasa, Kaichiro; Gailia Selaya, Nadezhda; Sillett, Stephen; Sterck, Frank; Takagi, Kentaro; Tange, Takeshi; Tanouchi, Hiroyuki; Tissue, David; Umehara, Tohru; Utsugi, Hajime; Vadeboncoeur, Matthew; Valladares, Fernando; Vanninen, Petteri; Wang, Jian; Wenk, Elizabeth; Williams, Dick; Ximenes, Fabiano de Aquino; Yamaba, Atsushi; Yamada, Toshihiro; Yamakura, Takuo; Yanai, Ruth; York, Robert

    2015-05-07

    Quantifying the amount of mass or energy invested in plant tissues is of fundamental interest across a range of disciplines, including ecology, forestry, ecosystem science, and climate change science (Niklas, 1994; Chave et al. 2005; Falster et al. 2011). The allocation of net primary production into different plant components is an important process affecting the lifetime of carbon in ecosystems, and resource use and productivity by plants (Cannell & Dewar, 1994; Litton et al. 2007; Poorter et al. 2012). While many studies in have destructively harvested woody plants in the name of science, most of these data have only been made available in the form of summary tables or figures included in publications. Until now, the raw data has resided piecemeal on the hard drives of individual scientists spread around the world. Several studies have gathered together the fitted (allometric) equations for separate datasets (Ter-Mikaelian & Korzukhin, 1997; Jenkins et al. 2003; Zianis et al. 2005; Henry et al. 2013), but none have previously attempted to organize and share the raw individual plant data underpinning these equations on a large scale. Gathered together, such data would represent an important resource for the community, meeting a widely recognised need for rich, open data resources to solve ecological problems (Costello et al. 2013; Fady et al. 2014; Harfoot & Roberts, 2014; Costello et al. 2013). We (D.S. Falster and R.A. Duursma, with the help of D.R. Barneche, R.G. FitzJohn and A. Vårhammar) set out to create such a resource, by asking authors directly whether they would be willing to make their raw data files freely available. The response was overwhelming: nearly everyone we contacted was interested to contribute their raw data. Moreover, we were invited to incorporate another compilation led by M. Ishihara and focussing on Japanese literature. As a result, we present BAAD: a Biomass And Allometry Database for woody plants, comprising data collected in 174

  20. Woody crops conference 2013; Agrarholz-Kongress 2013

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2013-06-01

    Within the Guelzow expert discussions at 19th and 20th February 2013 in Berlin (Federal Republic of Germany) the following lectures were held: (1) Research funding of the BMELV in the field of the production of woody crops (Andreas Schuette); (2) ELKE - Development of extensive concepts of land use for the production of renewable raw materials as possible compensatory measures and substitute measures (Frank Wegener); (3) Knowledge transfer to the realm of practice, experiences of the DLG (Frank Setzer); (4) Results of the tests with fast growing tree species after 18 years of cultivation in Guelzow (Andreas Gurgel); (5) Latest findings on the production of woody crops in Brandenburg (D. Murach); (6) Phytosanitary situation in short-rotation coppices in Germany - Current state of knowledge and prognoses for the future (Christiane Helbig); (7) Evaluation of alternative delivery procedures in short-rotation coppices (Janine Schweier); (8) With a short-rotation coppice shredder through Germany (Wolfram Kudlich); (9) Changes of land-use of traditional crops rotation systems to short-rotation coppices consisting of poplar trees and willow trees, which sites are suitable? - Selected results from the ProLoc association (Martin Hofmann); (10) Cultivation of populus tremula for short-rotation coppices at agricultural areas (Mirko Liesebach); (11) Investigations of the resistance behaviour of newly developed black poplar clones and balsam poplar clones against the poplar leave rust Melampsora larici-populina (Christina Fey-Wagner); (12) A agri-forestry system for ligneous energy production in the organic farming - First results from cultivation experiments in Bavaria (Klaus Wiesinger); (13) Implementation of agri-forestry systems with energy wood in the rural area - the project AgroForstEnergie (Armin Vetter); (14) Impact of agroforestry land utilization on microclimate, soil fertility and quality of water (Christian Boehm).

  1. Phytoliths in woody plants from the Miombo woodlands of Mozambique.

    Science.gov (United States)

    Mercader, Julio; Bennett, Tim; Esselmont, Chris; Simpson, Steven; Walde, Dale

    2009-07-01

    There are no descriptions of phytoliths produced by plants from the 'Zambezian' zone, where Miombo woodlands are the dominant element of the largest single phytochorion in sub-Saharan Africa. The preservation of phytoliths in fossil records of Africa makes phytoliths a tool to study early plant communities. Paleo-ethnobotanical interpretation of phytoliths relies on the comparison of ancient types with morphotypes extracted from living reference collections. Phytoliths were extracted from plant samples representing 41 families, 77 genera and 90 species through sonic cleaning, dry ashing and acid treatment; and phytoliths thus extracted were quantified. For each species, an average of 216 phytoliths were counted. The percentage of each morphotype identified per species was calculated, and types were described according to the descriptors from the International Code for Phytolith Nomenclature. Phytolith assemblages were subject to discriminant analysis, cluster analysis and principal component analysis. Phytoliths were grouped into 57 morphotypes (two were articulated forms and 55 were discrete shapes), and provide a reference collection of phytolith assemblages produced by Miombo woody species. Common and unique morphotypes are described and taxonomic and grouping variables are looked into from a statistical perspective. The first quantitative taxonomy of phytoliths from Miombos is presented here, including new types and constituting the most extensive phytolith key for any African ecoregion. Evidence is presented that local woody species are hypervariable silica producers and their phytolith morphotypes are highly polymorphic. The taxonomic significance of these phytoliths is largely poor, but there are important exceptions that include the morphotypes produced by members from >10 families and orders. The typical phytolithic signal that would allow scientists to identify ancient woodlands of 'Zambezian' affiliation comprises only half of the original number of

  2. The affect of a clearcut environment on woody debris respiration rate dynamics, Harvard Forest, Massachusetts

    Science.gov (United States)

    Vanderhoof, M. K.; Williams, C. L.

    2011-12-01

    At an ecosystem scale, the distribution of carbon is largely a function of stand development and disturbance processes. Clearcut logging remains a common practice both in the United States and globally and typically results in elevated storage of carbon in onsite woody debris and detritus. The residence time and decomposition rate of this woody debris and detritus will affect the rate of CO2 efflux to the atmosphere and thus affect the long term consequences of such disturbances on carbon flux and storage. The removal of a forest canopy also affects a site's microclimate including the albedo, air temperature, air humidity, as well as soil temperature and moisture, many of the same factors that affect the rate of woody debris decomposition. Thus it could be expected that differences in woody debris characteristics (e.g. size, abundance, state of decay), as well as differences in microclimate, between mature and recently clearcut forest sites, would result in differences in piece and site-level woody debris decomposition rates. Although woody debris stocks post-harvest have been well characterized, few studies have explored post-disturbance woody debris respiration rates, which directly measures carbon emissions from woody debris, distinguishing decomposition from mass loss due to fragmentation or leaching. This study addressed the question: does a clearcut environment in a temperate forest affect the rate of decomposition of coarse woody debris? The rate of respiration of downed spruce logs were repeatedly measured in-situ using an LI-6250 gas analyzer in Harvard Forest, Petersham, Massachusetts. Treatments included clear-cut, shaded clear-cut, mature spruce stand, and transfer (from clearcut to spruce stand). Gas analyzer measurements were accompanied by measurements of log temperature and percent water, soil temperature, moisture and pH, as well as light levels, air temperature and humidity to determine dominant drivers of respiration rates.

  3. Woody plant diversity and structure of shade-grown-coffee plantations in Northern Chiapas, Mexico

    Directory of Open Access Journals (Sweden)

    Lorena Soto-Pinto

    2001-12-01

    Full Text Available Shade-grown coffee is an agricultural system that contains some forest-like characteristics. However, structure and diversity are poorly known in shade coffee systems. In 61 coffee-growers’ plots of Chiapas, Mexico, structural variables of shade vegetation and coffee yields were measured, recording species and their use. Coffee stands had five vegetation strata. Seventy seven woody species mostly used as wood were found (mean density 371.4 trees per hectare. Ninety percent were native species (40% of the local flora, the remaining were introduced species, mainly fruit trees/shrubs. Diametric distribution resembles that of a secondary forest. Principal Coordinates Analysis grouped plots in four classes by the presence of Inga, however the majority of plots are diverse. There was no difference in equitability among groups or coffee yields. Coffee yield was 835 g clean coffee per shrub, or ca. 1668 kg ha-1. There is a significant role of shade-grown coffee as diversity refuge for woody plants and presumably associated fauna, as well as an opportunity for shade-coffee growers to participate in the new biodiversity-friendly-coffee marketEl café bajo sombra es un sistema agrícola que contiene algunas características de los bosques. Sin embargo, las características estructurales y de diversidad de la sombra del café son poco conocidas. En 61 parcelas de productores del norte de Chiapas, Mexico, se midieron variables estructurales de la vegetación de sombra y los rendimientos de café, registrando las especies y sus usos. Los cafetales presentaron cinco estratos de vegetación. Se encontraron 77 especies leñosas, la mayoría de uso maderable (densidad promedio de 371.4 árboles por hectárea. Noventa por ciento fueron especies nativas (40% de la flora local, el porcentaje restante fueron especies introducidas, principalmente árboles o arbustos frutales. La distribución diamétrica se asemeja a la distribución típica de bosques secundarios

  4. Soil characterization and differential patterns of heavy metal accumulation in woody plants grown in coal gangue wastelands in Shaanxi, China.

    Science.gov (United States)

    Yakun, Shi; Xingmin, Mu; Kairong, Li; Hongbo, Shao

    2016-07-01

    Soil contamination by heavy metals in coal mine wastelands is a significant environmental issue in most developing countries. The purpose of this study is to evaluate contamination characteristics in the coal mine wastelands of Sanlidong coal mine, Tongchuan, China. To achieve this goal, we conducted field sampling work, followed by further analysis of the properties of soil contamination and accumulation characteristics in woody plants. At this site, the pH value ranged from 4.41 to 7.88, and the nutrient content of the soil rose gradually with the time after deposition due to the weathering effect improving the soil quality. Meanwhile, the levels of Cd, Cr, Cu, Ni, and Zn gradually decreased with the passage time. Generally, heavy metal contamination was found to be more serious in the discharge refuse area, with Cd contamination at moderate or heavy levels; Ni, Zn, and Cu contamination at light levels; and with no Cr contamination. The geoaccumulation index (I geo) was highest for Cd (2.38-3.14), followed by Ni, Zn, Cu, and Cr. Heavy metals accumulated on the lower slopes and spread to the surrounding areas via hydrodynamic effects and wind. According to transfer and enrichment coefficient analyses, Robinia pseudoacacia, Ulmus pumila, and Hippophae rhamnoides with considerable biomass could be used as pollution-resistant tree species for vegetation restoration. This study provided a theoretical basis for the restoration of the ecological environment in the mining area. This report described a link between heavy metal contamination of soils and growth dynamics of woody plants in China.

  5. Characteristics of African Savanna Biomes for Determining Woody Cover

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set includes the soil and vegetation characteristics, herbivore estimates, and precipitation measurement data for the 854 sites described and analyzed in...

  6. Volatile organic emissions from the distillation and pyrolysis of vegetation

    Science.gov (United States)

    Greenberg, J. P.; Friedli, H.; Guenther, A. B.; Hanson, D.; Harley, P.; Karl, T.

    2005-09-01

    Leaf and woody plant tissue (Pinus ponderosa, Eucalyptus saligna, Quercus gambelli, Saccharum officinarum and Oriza sativa) were heated from 30 to 300°C and volatile organic compound (VOC) emissions were identified and quantified. Major VOC emissions were acetic acid, furylaldehyde, methyl acetate, pyrazine, terpenes, 2,3-butadione, phenol and methanol, as well as smaller emissions of furan, acetone, acetaldehyde, acetonitrile and benzaldehyde. Total VOC emissions from distillation and pyrolysis were on the order of 10 mgC/gC dry weight of vegetation, as much as 33% and 44% of CO2 emissions (gC(VOC)/gC(CO2)) measured during the same experiments, in air and nitrogen atmospheres, respectively. The emissions are similar in identity and quantity to those from smoldering combustion of woody tissue and of different character than those evolved during flaming combustion. VOC emissions from the distillation of pools and the pyrolysis of vegetation heated under low turbulence conditions produces concentrations near leaves that reach the lower limits of flammability and the emissions may be important in the propagation of wildfires. VOC emissions from charcoal production are also related to distillation and pyrolysis; the emissions of the highly reactive VOCs from production are as large as the carbon monoxide emissions.

  7. Global patterns of woody residence time and its influence on model simulation of aboveground biomass

    Science.gov (United States)

    Xue, Bao-Lin; Guo, Qinghua; Hu, Tianyu; Xiao, Jingfeng; Yang, Yuanhe; Wang, Guoqiang; Tao, Shengli; Su, Yanjun; Liu, Jin; Zhao, Xiaoqian

    2017-05-01

    Woody residence time (τw) is an important parameter that expresses the balance between mature forest recruitment/growth and mortality. Using field data collected from the literature, this study explored the global forest τw and investigated its influence on model simulations of aboveground biomass (AGB) at a global scale. Specifically, τw was found to be related to forest age, annual temperature, and precipitation at a global scale, but its determinants were different among various plant function types. The estimated global forest τw based on the filed data showed large spatial heterogeneity, which plays an important role in model simulation of AGB by a dynamic global vegetation model (DGVM). The τw could change the resulting AGB in tenfold based on a site-level test using the Monte Carlo method. At the global level, different parameterization schemes of the Integrated Biosphere Simulator using the estimated τw resulted in a twofold change in the AGB simulation for 2100. Our results highlight the influences of various biotic and abiotic variables on forest τw. The estimation of τw in our study may help improve the model simulations and reduce the parameter's uncertainty over the projection of future AGB in the current DGVM or Earth System Models. A clearer understanding of the responses of τw to climate change and the corresponding sophisticated description of forest growth/mortality in model structure is also needed for the improvement of carbon stock prediction in future studies.

  8. Mapping aboveground woody biomass using forest inventory, remote sensing and geostatistical techniques.

    Science.gov (United States)

    Yadav, Bechu K V; Nandy, S

    2015-05-01

    Mapping forest biomass is fundamental for estimating CO₂ emissions, and planning and monitoring of forests and ecosystem productivity. The present study attempted to map aboveground woody biomass (AGWB) integrating forest inventory, remote sensing and geostatistical techniques, viz., direct radiometric relationships (DRR), k-nearest neighbours (k-NN) and cokriging (CoK) and to evaluate their accuracy. A part of the Timli Forest Range of Kalsi Soil and Water Conservation Division, Uttarakhand, India was selected for the present study. Stratified random sampling was used to collect biophysical data from 36 sample plots of 0.1 ha (31.62 m × 31.62 m) size. Species-specific volumetric equations were used for calculating volume and multiplied by specific gravity to get biomass. Three forest-type density classes, viz. 10-40, 40-70 and >70% of Shorea robusta forest and four non-forest classes were delineated using on-screen visual interpretation of IRS P6 LISS-III data of December 2012. The volume in different strata of forest-type density ranged from 189.84 to 484.36 m(3) ha(-1). The total growing stock of the forest was found to be 2,024,652.88 m(3). The AGWB ranged from 143 to 421 Mgha(-1). Spectral bands and vegetation indices were used as independent variables and biomass as dependent variable for DRR, k-NN and CoK. After validation and comparison, k-NN method of Mahalanobis distance (root mean square error (RMSE) = 42.25 Mgha(-1)) was found to be the best method followed by fuzzy distance and Euclidean distance with RMSE of 44.23 and 45.13 Mgha(-1) respectively. DRR was found to be the least accurate method with RMSE of 67.17 Mgha(-1). The study highlighted the potential of integrating of forest inventory, remote sensing and geostatistical techniques for forest biomass mapping.

  9. β-Diversity of functional groups of woody plants in a tropical dry forest in Yucatan.

    Directory of Open Access Journals (Sweden)

    Jorge Omar López-Martínez

    Full Text Available Two main theories have attempted to explain variation in plant species composition (β-diversity. Niche theory proposes that most of the variation is related to environment (environmental filtering, whereas neutral theory posits that dispersal limitation is the main driver of β-diversity. In this study, we first explored how α- and β-diversity of plant functional groups defined by growth form (trees, shrubs and lianas, which represent different strategies of resource partitioning, and dispersal syndrome (autochory, anemochory and zoochory, which represent differences in dispersal limitation vary with successional age and topographic position in a tropical dry forest. Second, we examined the effects of environmental, spatial, and spatially-structured environmental factors on β-diversity of functional groups; we used the spatial structure of sampling sites as a proxy for dispersal limitation, and elevation, soil properties and forest stand age as indicators of environmental filtering. We recorded 200 species and 22,245 individuals in 276 plots; 120 species were trees, 41 shrubs and 39 lianas. We found that β-diversity was highest for shrubs, intermediate for lianas and lowest for trees, and was slightly higher for zoochorous than for autochorous and anemochorous species. All three dispersal syndromes, trees and shrubs varied in composition among vegetation classes (successional age and topographic position, whilst lianas did not. β-diversity was influenced mostly by proxies of environmental filtering, except for shrubs, for which the influence of dispersal limitation was more important. Stand age and topography significantly influenced α-diversity across functional groups, but showed a low influence on β-diversity -possibly due to the counterbalancing effect of resprouting on plant distribution and composition. Our results show that considering different plant functional groups reveals important differences in both α- and

  10. Fruits and vegetables (image)

    Science.gov (United States)

    A healthy diet includes adding vegetables and fruit every day. Vegetables like broccoli, green beans, leafy greens, zucchini, cauliflower, cabbage, carrots, and tomatoes are low in calories and high in fiber, vitamins, and minerals. ...

  11. Total Vegetation 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — These are polygons that contain vegetated pixels in the May, 2002 imagery from aerial overflight of the Grand Canyon. Vegetation was mapped between stage elevations...

  12. [Vital traits of woody species in High Andean forest edges of the Cogua Forest Reserve (Colombia)].

    Science.gov (United States)

    Montenegro, Alba Lucía; Vargas, Orlando

    2008-06-01

    The Cogua Forest Reserve was studied throughout eight months to detect the existence of functional species-groups associated with edge wood forest. A second goal was to determine which species were the most successful in edge areas and their particular vital traits. The regeneration and growth of the forest patches to the adjacent matrix depends on the establishment of these species and their tolerance to both habitats. Three types of High Andean edge forest were studied. Two forest patches were chosen for each of the three edge types: Chusquea scandens edge, "paramune" and old-edge; the name of the latter was given because of its advanced successional state. In each patch, the vegetation was evaluated in two 60 m transects perpendicular to the edge and along the matrix-edge-interior gradient of the forest. All woody species were identified and counted to determine their abundance. A total of nine species were chosen as representative of High Andean forest edges in the reserve, because of their high abundance in this environment, their presence in both patches of each edge type and their ability to colonize the adjacent matrix. Each species was evaluated using 20 vital attributes of individual, leaf, and reproductive traits. Six species groups were found through a Correspondence Analysis. However, all nine species have high variation and plasticity levels for the attributes, even inside the groups. This trend suggests that while they are not clearly differentiated functional groups, they probably are representing different strategies within a single functional group of great plasticity. Tibouchina grossa and Pentacalia Pulchella are found in all edge and matrix types; the other species are found in all edge types, except by Gaiadendron punctatum and Weinmannia tomentosa, absent in the Chusquea scandens edge. All nine species are important elements in the restoration of forest edges, mainly where they are more abundant, evidencing their success in the particular

  13. Papuacalia (Compositae). A new genus for the woody Senecios of New Guinea

    NARCIS (Netherlands)

    Veldkamp, J.F.

    1991-01-01

    The woody Senecio species occurring in New Guinea belong to a distinct genus, Papuacalia. Ten new combinations are made and three new species and one subspecies are described. Brachionostylum Mattf. and Bedfordia DC. are distinct

  14. Invertebrates Associated with Coarse Woody Debris in Streams, Upland Forests, and Wetlands: A Review

    Science.gov (United States)

    A. Braccia; D.P. Batzer

    1999-01-01

    We reviewed literature on the inbvertebrate groups associated with coarse woody debris in forests, streams, and wetlands, and contrasted patterns of invertebrate community development and wood decomposition among ecosystems.

  15. Interplanting woody nurse crops promotes differential growth of black walnut saplings

    Science.gov (United States)

    J. O. Dawson; J. W. Van Sambeek

    1993-01-01

    Interplanting black walnut (Juglans nigra) with four different nitrogen fixing, woody nurse crops (Alnus glutinosa, Elaeagnus umbellata, E. angustifolia or Caragana arborescens) increased annual walnut height and stem diameter (dbh) growth overall by as much as 50% and...

  16. Woody Biomass for Eastern U.S. Forests, 1983-1996

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: Estimates of the woody biomass density and pools were derived at the county scale of resolution of all forests of the eastern United States using new...

  17. Pretreatment of woody biomass for biofuel production: energy efficiency, technologies, and recalcitrance.

    Science.gov (United States)

    Zhu, J Y; Pan, Xuejun; Zalesny, Ronald S

    2010-07-01

    This mini review discusses several key technical issues associated with cellulosic ethanol production from woody biomass: energy consumption for woody biomass pretreatment, pretreatment energy efficiency, woody biomass pretreatment technologies, and quantification of woody biomass recalcitrance. Both total sugar yield and pretreatment energy efficiency, defined as the total sugar recovery divided by total energy consumption for pretreatment, should be used to evaluate the performance of a pretreatment process. A post-chemical pretreatment wood size-reduction approach was proposed to significantly reduce energy consumption. The review also emphasizes using a low liquid-to-wood ratio (L/W) to reduce thermal energy consumption for any thermochemical/physical pretreatment in addition to reducing pretreatment temperature.

  18. Boron deficiency in woody plants: various responses and tolerance mechanisms.

    Science.gov (United States)

    Wang, Nannan; Yang, Chengquan; Pan, Zhiyong; Liu, Yongzhong; Peng, Shu'ang

    2015-01-01

    Boron (B) is an essential microelement for higher plants, and its deficiency is widespread around the world and constrains the productivity of both agriculture and forestry. In the last two decades, numerous studies on model or herbaceous plants have contributed greatly to our understanding of the complex network of B-deficiency responses and mechanisms for tolerance. In woody plants, however, fewer studies have been conducted and they have not well been recently synthesized or related to the findings on model species on B transporters. Trees have a larger body size, longer lifespan and more B reserves than do herbaceous plants, indicating that woody species might undergo long-term or mild B deficiency more commonly and that regulation of B reserves helps trees cope with B deficiency. In addition, the highly heterozygous genetic background of tree species suggests that they may have more complex mechanisms of response and tolerance to B deficiency than do model plants. Boron-deficient trees usually exhibit two key visible symptoms: depression of growing points (root tip, bud, flower, and young leaf) and deformity of organs (root, shoot, leaf, and fruit). These symptoms may be ascribed to B functioning in the cell wall and membrane, and particularly to damage to vascular tissues and the suppression of both B and water transport. Boron deficiency also affects metabolic processes such as decreased leaf photosynthesis, and increased lignin and phenol content in trees. These negative effects will influence the quality and quantity of wood, fruit and other agricultural products. Boron efficiency probably originates from a combined effect of three processes: B uptake, B translocation and retranslocation, and B utilization. Root morphology and mycorrhiza can affect the B uptake efficiency of trees. During B translocation from the root to shoot, differences in B concentration between root cell sap and xylem exudate, as well as water use efficiency, may play key roles in

  19. Climber Diversity across Vegetational Landscape of North-Eastern Uttar Pradesh, India

    Directory of Open Access Journals (Sweden)

    Ashish DVIVEDI

    2016-12-01

    Full Text Available The composition and diversity of climbers among grassland, wasteland and forest vegetations was examined with respect to their woodiness, climbing mode and circumnutation pattern across the vegetational landscape of north-eastern Uttar Pradesh during 2011-2015. A total of 111 climbers, constituting 63 lianas and 48 vine species, under 35 families, were recorded. The forest and wasteland vegetation were quite similar in regard with climber diversity. Family Convolvulaceae included a maximum of 19 climbers. Majority of twining climbers showed right-handed twining.  The wasteland vegetation was most suitable and quite similar to forest habitat for vines as well as for lianas. The right handed circumnutation was the dominant pattern among the twiners of the region. Local climbing flora provides considerable natural resource to the region. They often create special micro-habitats and increase the complexity of the ecosystem.

  20. Vegetation as a driver of temporal variations in slope stability: The impact of hydrological processes

    Science.gov (United States)

    Kim, John H.; Fourcaud, Thierry; Jourdan, Christophe; Maeght, Jean-Luc; Mao, Zhun; Metayer, James; Meylan, Louise; Pierret, Alain; Rapidel, Bruno; Roupsard, Olivier; de Rouw, Anneke; Sanchez, Mario Villatoro; Wang, Yan; Stokes, Alexia

    2017-05-01

    Although vegetation is increasingly used to mitigate landslide risks, how vegetation affects the temporal variability of slope stability is poorly understood, especially in earthquake-prone regions. We combined 3-year long soil moisture monitoring, measurements of soil physical properties and plant functional traits, and numerical modeling to compare slope stability under paired land uses with and without trees in tropical, subtropical, and temperate landslide- and earthquake-prone regions. Trees improved stability for 5-12 months per year from drawdown of soil moisture and resulted in less interannual variability in the duration of high-stability periods compared to slopes without trees. Our meta-analysis of published data also showed that slopes with woody vegetation were more stable and less sensitive to climate and soil factors than slopes with herbaceous vegetation. However, estimates of earthquake magnitude necessary to destabilize slopes at our sites suggest that large additional stabilization from trees is necessary for meaningful protection against external triggers.

  1. Vegetation geographical patterns as a key to the past, with emphasis on the dry vegetation types of South Africa

    Directory of Open Access Journals (Sweden)

    M. J. A. Werger

    1983-12-01

    Full Text Available Southern Africa is characterized by a highly diversified vegetational cover with extremes as contrasting as desert, tropical forest, alpine grassland, or mediterranean type scrub, and many other types in between. This vegetational pattern is strongly correlated to the climatological pattern. It is therefore likely that past changes in climate can still be partly traced in the vegetational pattern, particularly in geographical anomalies, and that study of these patterns provides complementary evidence to palynological research. The following anomalies in the vegetational pattern are briefly discussed: 1. island-wise occurrence of Afro-montane vegetation on mesic, sheltered sites in the southern Sudano- Zambezian Region, in particular in the Highveld grassland/False Karoo transition area; 2. similar westward occurrence of Sudano-Zambezian scrub patches in the Karoo-Namib Region near the Orange/Vaal confluence; 3. scattered occurrence of Sudano-Zambezian woody species in a matrix of Karoo-Namib vegetation in the marginal Karoo-Namib Region; 4. island-wise occurrence of frost-tolerant, dry, karroid dwarf shrub vegetation of predominantly C,-plants on isolated peaks in the winter rainfall area of Namaqualand; 5. peculiar patchy distribution of some succulents in wide areas of climatically rather homogeneous, succulent dwarf shrub vegetation of predominantly CAM-plants in the escarpment area of Namaqualand. a pattern reminiscent of that in many Cape fynbos species. Interpretation of these patterns logically leads to the conclusion that these result from a previously wetter, a previously cooler, or a previously wetter and cooler climate, respectively, over the parts of southern Africa under discussion. This conclusion is compared with published palynological views.

  2. Trade-offs between savanna woody plant diversity and carbon storage in the Brazilian Cerrado.

    Science.gov (United States)

    Pellegrini, Adam F A; Socolar, Jacob B; Elsen, Paul R; Giam, Xingli

    2016-10-01

    Incentivizing carbon storage can be a win-win pathway to conserving biodiversity and mitigating climate change. In savannas, however, the situation is more complex. Promoting carbon storage through woody encroachment may reduce plant diversity of savanna endemics, even as the diversity of encroaching forest species increases. This trade-off has important implications for the management of biodiversity and carbon in savanna habitats, but has rarely been evaluated empirically. We quantified the nature of carbon-diversity relationships in the Brazilian Cerrado by analyzing how woody plant species richness changed with carbon storage in 206 sites across the 2.2 million km(2) region at two spatial scales. We show that total woody plant species diversity increases with carbon storage, as expected, but that the richness of endemic savanna woody plant species declines with carbon storage both at the local scale, as woody biomass accumulates within plots, and at the landscape scale, as forest replaces savanna. The sharpest trade-offs between carbon storage and savanna diversity occurred at the early stages of carbon accumulation at the local scale but the final stages of forest encroachment at the landscape scale. Furthermore, the loss of savanna species quickens in the final stages of forest encroachment, and beyond a point, savanna species losses outpace forest species gains with increasing carbon accumulation. Our results suggest that although woody encroachment in savanna ecosystems may provide substantial carbon benefits, it comes at the rapidly accruing cost of woody plant species adapted to the open savanna environment. Moreover, the dependence of carbon-diversity trade-offs on the amount of savanna area remaining requires land managers to carefully consider local conditions. Widespread woody encroachment in both Australian and African savannas and grasslands may present similar threats to biodiversity. © 2016 John Wiley & Sons Ltd.

  3. Grazing limits natural biological controls of woody encroachment in Inner Mongolia Steppe.

    Science.gov (United States)

    Guo, Hongyu; Guan, Linjing; Wang, Yinhua; Xie, Lina; Prather, Chelse M; Liu, Chunguang; Ma, Chengcang

    2017-10-15

    Woody encroachment in grasslands has become increasingly problematic globally. Grazing by domestic animals can facilitate woody encroachment by reducing competition from herbaceous plants and fire frequency. Herbivorous insects and parasitic plants can each exert forces that result in the natural biological control of encroaching woody plants through reducing seeding of their host woody plants. However, the interplay of grazing and dynamics of herbivorous insects or parasitic plants, and its effects on the potential biological control of woody encroachment in grasslands remains unclear. We investigated the flower and pod damage by herbivorous insects, and the infection rates of a parasitic plant on the shrub Caragana microphylla , which is currently encroaching in Inner Mongolia Steppe, under different grazing management treatments (33-year non-grazed, 7-year non-grazed, currently grazed). Our results showed that Caragana biomass was highest at the currently grazed site, and lowest at the 33-year non-grazed site. Herbaceous plant biomass followed the opposite pattern, suggesting that grazing is indeed facilitating the encroachment of Caragana plants in Inner Mongolia Steppe. Grazing also reduced the abundance of herbivorous insects per Caragana flower, numbers of flowers and pods damaged by insect herbivores, and the infection rates of the parasitic plant on Caragana plants. Our results suggest that grazing may facilitate woody encroachment in grasslands not only through canonical mechanisms (e.g. competitive release via feeding on grasses, reductions in fires, etc.), but also by limiting natural biological controls of woody plants (herbivorous insects and parasitic plants). Thus, management efforts must focus on preventing overgrazing to better protect grassland ecosystems from woody encroachment. © 2017. Published by The Company of Biologists Ltd.

  4. Carbon Stocks of Fine Woody Debris in Coppice Oak Forests at Different Development Stages

    Directory of Open Access Journals (Sweden)

    Ender Makineci

    2017-06-01

    Full Text Available Dead woody debris is a significant component of the carbon cycle in forest ecosystems. This study was conducted in coppice-originated oak forests to determine carbon stocks of dead woody debris in addition to carbon stocks of different ecosystem compartments from the same area and forests which were formerly elucidated. Weight and carbon stocks of woody debris were determined with recent samplings and compared among development stages (diameter at breast height (DBH, D1.3m, namely small-diameter forests (SDF = 0–8 cm, medium diameter forests (MDF = 8–20 cm, and large-diameter forests (LDF = 20–36 cm. Total woody debris was collected in samplings; as bilateral diameters of all woody debris parts were less than 10 cm, all woody parts were in the “fine woody debris (FWD” class. The carbon concentrations of FWD were about 48% for all stages. Mass (0.78–4.92 Mg·ha−1 and carbon stocks (0.38–2.39 Mg·ha−1 of FWD were significantly (p > 0.05 different among development stages. FWD carbon stocks were observed to have significant correlation with D1.3m, age, basal area, and carbon stocks of aboveground biomass (Spearman rank correlation coefficients; 0.757, 0.735, 0.709, and 0.694, respectively. The most important effects on carbon budgets of fine woody debris were determined to be coppice management and intensive utilization. Also, national forestry management, treatments of traditional former coppice, and conversion to high forest were emphasized as having substantial effects.

  5. The role of short-rotation woody crops in sustainable development

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, J.P. [National Council of the Paper Industry for Air and Stream Improvement, Medford, MA (United States); Tolbert, V.R. [Oak Ridge National Lab., TN (United States)

    1996-12-31

    One answer to increase wood production is by increasing management intensity on existing timberland, especially in plantation forests. Another is to convert land currently in agriculture to timberland. Short-rotation woody crops can be used in both cases. But, what are the environmental consequences? Short-rotation woody crops can provide a net improvement in environmental quality at both local and global scales. Conversion of agricultural land to short-rotation woody crops can provide the most environmental quality enhancement by reducing erosion, improving soil quality, decreasing runoff, improving groundwater quality, and providing better wildlife habitat. Forest products companies can use increased production from intensively managed short-rotation woody crop systems to offset decreased yield from the portion of their timberland that is managed less intensively, e.g. streamside management zones and other ecologically sensitive or unique areas. At the global scale, use of short-rotation woody crops for bioenergy is part of the solution to reduce greenhouse gases produced by burning fossil fuels. Incorporating short-rotation woody crops into the agricultural landscape also increases storage of carbon in the soil, thus reducing atmospheric concentrations. In addition, use of wood instead of alternatives such as steel, concrete, and plastics generally consumes less energy and produces less greenhouse gases. Cooperative research can be used to achieve energy, fiber, and environmental goals. This paper will highlight several examples of ongoing cooperative research projects that seek to enhance the environmental aspects of short-rotation woody crop systems. Government, industry, and academia are conducting research to study soil quality, use of mill residuals, nutrients in runoff and groundwater, and wildlife use of short-rotation woody crop systems in order to assure the role of short-rotation crops as a sustainable way of meeting society`s needs.

  6. A 6 year longitudinal study of post-fire woody carbon dynamics in California's forests

    Science.gov (United States)

    Bianca N.I. Eskelson; Vicente J. Monleon; Jeremy S. Fried

    2016-01-01

    We examined the dynamics of aboveground forest woody carbon pools — live trees, standing dead trees, and down wood—during the first 6 years following wildfire across a wide range of conditions, which are characteristic of California forest fires. From repeated measurements of the same plots, we estimated change in woody carbon pools as a function of crown fire severity...

  7. Grazing limits natural biological controls of woody encroachment in Inner Mongolia Steppe

    Directory of Open Access Journals (Sweden)

    Hongyu Guo

    2017-10-01

    Full Text Available Woody encroachment in grasslands has become increasingly problematic globally. Grazing by domestic animals can facilitate woody encroachment by reducing competition from herbaceous plants and fire frequency. Herbivorous insects and parasitic plants can each exert forces that result in the natural biological control of encroaching woody plants through reducing seeding of their host woody plants. However, the interplay of grazing and dynamics of herbivorous insects or parasitic plants, and its effects on the potential biological control of woody encroachment in grasslands remains unclear. We investigated the flower and pod damage by herbivorous insects, and the infection rates of a parasitic plant on the shrub Caragana microphylla, which is currently encroaching in Inner Mongolia Steppe, under different grazing management treatments (33-year non-grazed, 7-year non-grazed, currently grazed. Our results showed that Caragana biomass was highest at the currently grazed site, and lowest at the 33-year non-grazed site. Herbaceous plant biomass followed the opposite pattern, suggesting that grazing is indeed facilitating the encroachment of Caragana plants in Inner Mongolia Steppe. Grazing also reduced the abundance of herbivorous insects per Caragana flower, numbers of flowers and pods damaged by insect herbivores, and the infection rates of the parasitic plant on Caragana plants. Our results suggest that grazing may facilitate woody encroachment in grasslands not only through canonical mechanisms (e.g. competitive release via feeding on grasses, reductions in fires, etc., but also by limiting natural biological controls of woody plants (herbivorous insects and parasitic plants. Thus, management efforts must focus on preventing overgrazing to better protect grassland ecosystems from woody encroachment.

  8. Boron deficiency in woody plants: various responses and tolerance mechanisms

    Directory of Open Access Journals (Sweden)

    Nannan eWang

    2015-10-01

    Full Text Available Boron (B is an essential microelement for higher plants, and its deficiency is widespread around the world and constrains the productivity of both agriculture and forestry. In the last decades, accumulating studies on model or herbaceous plants have contributed greatly to our understanding of the complex network of B-deficiency responses and mechanisms for tolerance. In woody plants, however, only a few studies have been conducted and they are not well synthesised. Trees have a larger body size, longer lifespan and more B reserves than do herbaceous plants, indicating that woody species might undergo long-term or mild B deficiency more commonly and that a more complicated B reserves must accordingly be developed to cope with B deficiency. In addition, the highly heterozygous genetic background of tree species suggests that they may have a more complicated mechanism of response and tolerance to B deficiency than do model plants.B-deficient trees usually exhibit two key visible symptoms: depression of growing points (root tip, bud, flower, and young leaf and deformity of organs (root, shoot, leaf, and fruit. These symptoms may be ascribed to B functioning in the cell wall and membrane, and B deficiency results in damage to vascular tissues and the suppression of both B and water transport. B deficiency also affects metabolic processes, such as increased lignin and phenol, and decreased leaf photosynthesis. These negative effects will influence the quality and quantity of wood, fruit and other agricultural products.B efficiency probably originates from a combined effect of three processes: B uptake, B translocation and retranslocation, and B utilization. Root morphology and mycorrhiza can affect the B uptake efficiency of trees. During B translocation from the root to shoot, differences in B concentration between root cell saps and xylem exudates, as well as water use efficiency, may play key roles in tolerance to B deficiency. In addition, B

  9. Influence of aerogenic contamination on phytoncide activity of woody plants

    Directory of Open Access Journals (Sweden)

    S. O. Volodarez

    2015-07-01

    Full Text Available The main objective of this paper is to determine variations of antimicrobial activity of the volatile organic compounds from leaves of woody plants, which are growing on the areas with the different air pollution degree in the south-east of Ukraine. The research objects were Aesculus hippocastanum L., Betula pendula Roth, Salix alba L., Picea pungens Engelm. in Donetsk, Ukraine, and 6 species (Betula pendula Roth, Fraxinus excelsior L., Robinia pseudoacacia L., Populus nigra L., Tilia cordata Mill., Picea pungens Engelm. in Kramatorsk, Ukraine. Samples were collected in Donetsk every month during 2012 and 2013 years on four sample areas. Three research areas border with Donetsk Metallurgical Plant PSC, heavy traffic road and Kalinin coal mine, that feature such pollutants as CO2, SO2, NO2, and marsh gas. The fourth research area is the recreation zone (Donetsk Culture and Leisure Park near Donbass Arena stadium. The control area is located in the Donetsk Botanical Garden. The leaves from trees in Kramatorsk were collected in July and August 2013 on the sample area. The research area borders with Novokramatorsk Machine-building Plant JSC, which also features CO2, SO2, NO2 and other pollutants. The control area is located in the Jubilejnyi park. The research proves that antimicrobial activity of the volatile organic compounds from leaves of species under studyis sensitive to the impact of pollutants. Moreover, the antimicrobial activity of leaves B. pendula, S. alba, F. excelsior, R. pseudoacacia, P. nigra increases under the influence of pollutants from metallurgical plants and traffic exhausts. The antimicrobial ability of A. hippocastanum, T. cordata and P. pungens enhances in the areas with the cleaner air. These species are not gas-resistant species. Consequently, gas-resistant species feature the higher antimicrobial activity in the conditions of contamination. The other benefit of this study consists in monitoring of the seasonal

  10. Variation in woody plant mortality and dieback from severe drought among soils, plant groups, and species within a northern Arizona ecotone.

    Science.gov (United States)

    Koepke, Dan F; Kolb, Thomas E; Adams, Henry D

    2010-08-01

    Vegetation change from drought-induced mortality can alter ecosystem community structure, biodiversity, and services. Although drought-induced mortality of woody plants has increased globally with recent warming, influences of soil type, tree and shrub groups, and species are poorly understood. Following the severe 2002 drought in northern Arizona, we surveyed woody plant mortality and canopy dieback of live trees and shrubs at the forest-woodland ecotone on soils derived from three soil parent materials (cinder, flow basalt, sedimentary) that differed in texture and rockiness. Our first of three major findings was that soil parent material had little effect on mortality of both trees and shrubs, yet canopy dieback of trees was influenced by parent material; dieback was highest on the cinder for pinyon pine (Pinus edulis) and one-seed juniper (Juniperus monosperma). Ponderosa pine (Pinus ponderosa) dieback was not sensitive to parent material. Second, shrubs had similar mortality, but greater canopy dieback, than trees. Third, pinyon and ponderosa pines had greater mortality than juniper, yet juniper had greater dieback, reflecting different hydraulic characteristics among these tree species. Our results show that impacts of severe drought on woody plants differed among tree species and tree and shrub groups, and such impacts were widespread over different soils in the southwestern U.S. Increasing frequency of severe drought with climate warming will likely cause similar mortality to trees and shrubs over major soil types at the forest-woodland ecotone in this region, but due to greater mortality of other tree species, tree cover will shift from a mixture of species to dominance by junipers and shrubs. Surviving junipers and shrubs will also likely have diminished leaf area due to canopy dieback.

  11. Water uptake can occur through woody portions of roots and facilitates localized embolism repair in grapevine.

    Science.gov (United States)

    Cuneo, Italo F; Knipfer, Thorsten; Mandal, Pratiti; Brodersen, Craig R; McElrone, Andrew J

    2018-02-20

    Water acquisition is thought to be limited to the unsuberized surface located close to root tips. However, there are recurring periods when the unsuberized surfaces are limited in woody root systems, and radial water uptake across the bark of woody roots might play an important physiological role in hydraulic functioning. Using X-ray microcomputed tomography (microCT) and hydraulic conductivity measurements (Lp r ), we examined water uptake capacity of suberized woody roots in vivo and in excised samples. Bark hydration in grapevine woody roots occurred quickly upon exposure to water (c. 4 h). Lp r measurements through the bark of woody roots showed that it is permeable to water and becomes more so upon wetting. After bark hydration, microCT analysis showed that absorbed water was utilized to remove embolism locally, where c. 20% of root xylem vessels refilled completely within 15 h. Embolism removal did not occur in control roots without water. Water uptake through the bark of woody roots probably plays an important role when unsuberized tissue is scarce/absent, and would be particularly relevant following large irrigation events or in late winter when soils are saturated, re-establishing hydraulic functionality before bud break. No claim to original US Government works New Phytologist © 2018 New Phytologist Trust.

  12. Responses of Natural Vegetation to Different Stages of Extreme Drought during 2009–2010 in Southwestern China

    Directory of Open Access Journals (Sweden)

    Xiang Zhao

    2015-10-01

    Full Text Available An extreme drought event is usually a long-term process with different stages. Although it is well known that extreme droughts that have occurred frequently in recent years can substantially affect vegetation growth, few studies have revealed the characteristics of vegetation responses for different stages of an extreme drought event. Especially, studies should address when the vegetation growth was disturbed and how it recovered through an extreme drought event. In this study, we used the Normalized Difference Vegetation Index (NDVI and Palmer Drought Severity Index (PDSI to evaluate the response of vegetation to different stages of a severe drought event during 2009–2010 throughout Southwestern China. The PDSI time series indicated that the drought can be divided into three stages, including an initial stage represented by moderate drought (S1, a middle stage represented by continual severe drought (S2, and a final recovery stage (S3. The results revealed that the drought during the initial stage inhibited the growth of grassland and woody savanna, however, forest growth did not decrease during the first stage of droughts, and there was even a trend towards higher NDVI values. The continual severe drought in the middle stage inhibited growth for all vegetation types, and the woody savanna was affected most severely. In the final stage, all vegetation types underwent recovery, including the grassland that had endured the most severe drought. This study provides observational evidence and reveals that the responses of forest to the extreme drought are different from grassland and woody savanna in the different drought stages.

  13. Monitoring vegetation dynamics and carbon stock density in miombo woodlands.

    Science.gov (United States)

    Ribeiro, Natasha S; Matos, Céu N; Moura, Isabel R; Washington-Allen, Robert A; Ribeiro, Ana I

    2013-11-09

    The United Nation's Program for Reducing Emissions from Deforestation and Forest Degradation (REDD+) aims to reduce the 20% contribution to global emissions of greenhouse gases from the forest sector, offering a financial value of the carbon stored in forests as an incentive for local communities. The pre-requisite for the setup of a participatory REDD + Program is the monitoring, reporting and verification (MRV) of baseline carbon stocks and their changes over time. In this study, we investigated miombo woodland's dynamics in terms of composition, structure and biomass over a 4-year period (2005-2009), and the Carbon Stock Density (CSD) for the year 2009. The study was conducted in the Niassa National Reserve (NNR) in northern Mozambique, which is the 14th largest protected area in the world. Mean tree density distributed across 79 species increased slightly between 2005 and 2009, respectively, from 548 to 587 trees ha-1. Julbernardia globiflora (Benth.) was the most important species in this area [importance value index (IVI2005= 61 and IVI2009 = 54)]. The woodlands presented an inverted J-shaped diametric curve, with 69% of the individuals representing the young cohort. Woody biomass had a net increase of 3 Mg ha-1 with the highest growth observed in Dyplorhynchus condilocarpon (Müll.Arg.) Pichon (0.54 Mg ha-1). J. globiflora had a net decrease in biomass of 0.09 Mg ha-1. Total CSD density was estimated at ca. 67 MgC ha-1 ± 24.85 with soils (average 34.72 ± 17.93 MgC ha-1) and woody vegetation (average 29.8 MgC ha-1 ± 13.07) representing the major carbon pools. The results point to a relatively stable ecosystem, but they call for the need to refocus management activities. The miombo woodlands in NNR are representative of the woodlands in the eco-region in terms of vegetation structure and composition. They experienced net increase in woody biomass, a considerable recruitment level and low mortality. According to our results, NNR

  14. Hydrogen-free catalytic fractionation of woody biomass.

    Science.gov (United States)

    Galkin, Maxim V; Smit, Arjan T; Subbotina, Elena; Artemenko, Konstantin A; Bergquist, Jonas; Huijgen, Wouter J J; Samec, Joseph S M

    2016-12-08

    The pulping industry could become a biorefinery if the lignin and hemicellulose components of the lignocellulose are valorized. Conversion of lignin into well-defined aromatic chemicals is still a major challenge. Lignin depolymerization reactions often occur in parallel with irreversible condensation reactions of the formed fragments. Here, we describe a strategy that markedly suppresses the undesired condensation pathways and allows to selectively transform lignin into a few aromatic compounds. Notably, applying this strategy to woody biomass at organosolv pulping conditions, the hemicellulose, cellulose, and lignin were separated and in parallel the lignin was transformed into aromatic monomers. In addition, we were able to utilize a part of the lignocellulose as an internal source of hydrogen for the reductive lignin transformations. We hope that the presented methodology will inspire researchers in the field of lignin valorization as well as pulp producers to develop more efficient biomass fractionation processes in the future. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Using Landsat Vegetation Indices to Estimate Impervious Surface Fractions for European Cities

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    Per Skougaard Kaspersen

    2015-06-01

    Full Text Available Impervious surfaces (IS are a key indicator of environmental quality, and mapping of urban IS is important for a wide range of applications including hydrological modelling, water management, urban and environmental planning and urban climate studies. This paper addresses the accuracy and applicability of vegetation indices (VI, from Landsat imagery, to estimate IS fractions for European cities. The accuracy of three different measures of vegetation cover is examined for eight urban areas at different locations in Europe. The Normalized Difference Vegetation Index (NDVI and Soil Adjusted Vegetation Index (SAVI are converted to IS fractions using a regression modelling approach. Also, NDVI is used to estimate fractional vegetation cover (FR, and consequently IS fractions. All three indices provide fairly accurate estimates (MAEs ≈ 10%, MBE’s < 2% of sub-pixel imperviousness, and are found to be applicable for cities with dissimilar climatic and vegetative conditions. The VI/IS relationship across cities is examined by quantifying the MAEs and MBEs between all combinations of models and urban areas. Also, regional regression models are developed by compiling data from multiple cities to examine the potential for developing and applying a single regression model to estimate IS fractions for numerous urban areas without reducing the accuracy considerably. Our findings indicate that the models can be applied broadly for multiple urban areas, and that the accuracy is reduced only marginally by applying the regional models. SAVI is identified as a superior index for the development of regional quantification models. The findings of this study highlight that IS fractions, and spatiotemporal changes herein, can be mapped by use of simple regression models based on VIs from remote sensors, and that the method presented enables simple, accurate and resource efficient quantification of IS.

  16. Analysis of Vegetation Phytosociological Characteristics and Soil Physico-Chemical Conditions in Harishin Rangelands of Eastern Ethiopia

    OpenAIRE

    Haftay Hailu

    2017-01-01

    The objective of this study is to analyse the phytodiversity, distribution, herb biomass and physico-chemical conditions of the vegetation system in the context of communal continuous open grazing and enclosed grazing management practices in the Harishin rangelands of Eastern Ethiopia. A total of 58 herbaceous species and 11 woody species were recorded in the study area. Analysis of Importance Value Index for two management practices was represented by different combinations of species with v...

  17. Echohydrology of a floodplain forest: relationships between vegetation and groundwater resources at Congaree National Park, South Carolina USA

    Science.gov (United States)

    Timothy Callahan; Lauren Senn

    2016-01-01

    The goal of this project was to investigate the relationship between the shallow, unconfined aquifer and woody vegetation at eight sites of the Congaree Observation Well Network at Congaree National Park near Hopkins, South Carolina. Eight piezometers with screens of 1.5-m length (top-of-screen depths ranging from 3.0 to 5.0 m below ground surface) along a 1.8-km cross...

  18. Hydrological effect of vegetation against rainfall-induced landslides

    Science.gov (United States)

    Gonzalez-Ollauri, Alejandro; Mickovski, Slobodan B.

    2017-06-01

    The hydrological effect of vegetation on rainfall-induced landslides has rarely been quantified and its integration into slope stability analysis methods remains a challenge. Our goal was to establish a reproducible, novel framework to evaluate the hydrological effect of vegetation on shallow landslides. This was achieved by accomplishing three objectives: (i) quantification in situ of the hydrological mechanisms by which woody vegetation (i.e. Salix sp.) might impact slope stability under wetting and drying conditions; (ii) to propose a new approach to predict plant-derived matric suctions under drying conditions; and (iii) to evaluate the suitability of the unified effective stress principle and framework (UES) to quantify the hydrological effect of vegetation against landslides. The results revealed that plant water uptake was the main hydrological mechanism contributing to slope stability, as the vegetated slope was, on average, 12.84% drier and had matric suctions three times higher than the fallow slope. The plant-related mechanisms under wetting conditions had a minimal effect on slope stability. The plant aerial parts intercepted up to 26.73% of the rainfall and concentrated a further 10.78% of it around the stem. Our approach successfully predicted the plant-derived matric suctions and UES proved to be adequate for evaluating the hydrological effect of vegetation on landslides. Although the UES framework presented here sets the basis for effectively evaluating the hydrological effect of vegetation on slope stability, it requires knowledge of the specific hydro-mechanical properties of plant-soil composites and this in itself needs further investigation.

  19. Assessment of Soil Seedbank Composition of Woody Species in ...

    African Journals Online (AJOL)

    There was also significant variation of seed distribution between soil layers of the four selected forest sites (p<0.05). Jaccard's coefficient of similarity between the standing vegetation and soil seedbank showed low value (JCS = 0.21 - 0.43). From the results, appropriate management strategies including preparation of ...

  20. Effect of non-crop vegetation types on conservation biological control of pests in olive groves

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    Daniel Paredes

    2013-07-01

    Full Text Available Conservation biological control (CBC is an environmentally sound potential alternative to the use of chemical insecticides. It involves modifications of the environment to promote natural enemy activity on pests. Despite many CBC studies increasing abundance of natural enemies, there are far fewer demonstrations of reduced pest density and very little work has been conducted in olive crops. In this study we investigated the effects of four forms of non-crop vegetation on the abundance of two important pests: the olive psyllid (Euphyllura olivina and the olive moth (Prays oleae. Areas of herbaceous vegetation and areas of woody vegetation near olive crops, and smaller patches of woody vegetation within olive groves, decreased pest abundance in the crop. Inter-row ground covers that are known to increase the abundance of some predators and parasitoids had no effect on the pests, possibly as a result of lack of synchrony between pests and natural enemies, lack of specificity or intra-guild predation. This study identifies examples of the right types of diversity for use in conservation biological control in olive production systems.

  1. Vegetation structure and small-scale pattern in Miombo Woodland, Marondera, Zimbabwe

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    B. M. Campbell

    1995-10-01

    Full Text Available The aim ol this paper is to describe woodland structure and small-scale patterning of woody plants at a miombo site, and to relate these to past disturbance and soil properties. Brachystegia spiciformis Benth. and Julbemardia globiflora (Benth. Troupin were the most frequent woody plants at the five hectare site, with size-class distributions which were markedly skewed towards the smaller size classes. The vegetation structure at the site and the increase in basal area over the past thirty years point to considerable disturbance prior to the present protected status. Six woodland subtypes were identified, grouped into two structural types: open and closed woodland. The distribution of woodland subtypes related closely to certain soil properties. It was hypothesized that the distribution of open and closed woodland is stable and a positive feedback mechanism by which this occurs is postulated.

  2. Experimental and field investigations on uprooting of riparian vegetation

    Science.gov (United States)

    Calvani, Giulio; Francalanci, Simona; Solari, Luca; Gumiero, Bruna

    2017-04-01

    The morphology of a river reach is the result of many processes involving the motion of sediment (erosion, transport and deposition), the hydrological regime and the development and growth of vegetation. River evolution in the presence of vegetation depends on establishment of pioneer woody riparian seedlings on bars, and consequently on either their survival or death. Flooding events can cause young vegetation mortality by uprooting (Corenblit et al., 2007). These processes, despite their important implications on river morphodynamics, have been poorly investigated in the past. Most of previous research focused on the mechanism of root breakage and on measuring the vegetation resistance to uprooting in the vertical direction, while few works considered the effect of flow direction on the uprooting process (Bywater-Reyes et al., 2015). In this work, we focused on vegetation uprooting due to flow and to bed erosion. We considered two different types of vegetation: Avena Sativa, grown from seeds in external boxes, was used to investigate instantaneous uprooting, and Salix Purpurea, collected in the field, for delayed uprooting (namely type I and type II mechanisms, according to Edmaier et al., 2011). The experiments were carried out in a 5 m long flume in the Hydraulic Laboratory in Florence. A 2 m long mobile bed was build inside the flume, and vegetation was arranged according to several configurations on it. Both types of vegetation were subject to constant discharges to investigate the effects of a general bed degradation in modifying the occurrence of uprooting. We also performed some experiments with Avena Sativa located in a fixed bed and subjected to an increasing flow discharge in order to simulate instantaneous uprooting due to the action of hydrodynamic forces. We measured flow velocity, flow discharge and water depth and characterized vegetation by stem and root diameter, height and root length. The experimental results have been interpreted in terms of a

  3. Mapping alien and indigenous vegetation in the KwaZulu-Natal Sandstone Sourveld using remotely sensed data

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    John Odindi

    2016-11-01

    Full Text Available Background: The indigenous KwaZulu-Natal Sandstone Sourveld (KZN SS grassland is highly endemic and species-rich, yet critically endangered and poorly conserved. Ecological threats to this grassland ecosystem are exacerbated by encroachment of woody plants, with severe negative environmental and economic consequences. Hence, there is an increasing need to reliably determine the extent of encroached or invaded areas to design optimal mitigation measures. Because of inherent limitations that characterise traditional approaches like field surveys and aerial photography, adoption of remotely sensed data offer reliable and timely mapping of landscape processes.Objectives: We sought to map the distribution of woody vegetation within the KZN SS using remote sensing approaches.Method: New generation RapidEye imagery, characterised by strategically positioned bands, and the advanced machine learning algorithm Random Forest (RF were used to determine the distribution and composition of alien and indigenous woody vegetation within the KZN SS.Results: Results show that alien and indigenous encroachment and invasion could be mapped with over 86% accuracy whilst the dominant indigenous and alien tree species could be mapped with over 74% accuracy. These results highlight the potential of new generation RapidEye satellite data in combination with advanced machine learning technique in predicting the distribution of alien and indigenous woody cover within a grassland ecosystem. The successful discrimination of the two classes and the species within the classes can be attributed to the additional strategically positioned bands, particularly the red-edge in the new generation RapidEye image.Conclusion: Results underscore the potential of new generation RapidEye satellite data with strategically positioned bands and an advanced machine learning algorithm in predicting the distribution of woody cover in a grassland ecosystem.

  4. Dynamic aspects of large woody debris in river channels

    Science.gov (United States)

    Vergaro, Alexandra; Caporali, Enrica; Becchi, Ignazio

    2015-04-01

    Large Woody Debris (LWD) are an integral component of the fluvial environment. They represent an environmental resource, but without doubt they represent also a risk factor for the amplification that could give to the destructive power of a flood event. While countless intervention in river channels have reintroduced wood in rivers with restoration and banks protection aims, during several flash flood events LWD have had a great part in catastrophic consequences, pointing out the urgency of an adequate risk assessment procedure. At present wood dynamics in rivers is not systematically considered within the procedures for the elaboration of hazard maps resulting in loss of prediction accuracy and underestimation of hazard impacts. The assessment inconsistency comes from the complexity of the question: several aspects in wood processes are not yet well known and the superposition of different physical phenomena results in great difficulty to predict critical scenarios. The presented research activity has been aimed to improve management skills for the assessment of the hydrologic risk associated to the presence of large woody debris in rivers, improving knowledge about LWD dynamic processes and proposing effective tools for monitoring and mapping river catchments vulnerability. Utilizing critical review of the published works, field surveys and experimental investigations LWD damaging potential has been analysed to support the identification of the exposed sites and the redaction of hazard maps, taking into account that a comprehensive procedure has to involve: a) Identification of the critical cross sections; b) Evaluation of wood availability in the river catchment; c) Prediction of hazard scenarios through the estimation of water discharge, wood recruitment and entrainment, wood transport and destination. Particularly, a survey sheets form for direct measurements has been implemented and tested in field to provide an investigation instruments for wood and river

  5. DETERMINATION OF CRYSTALLINITY INDEX OF CARBOHYDRATE COMPONENTS IN HEMP (CANNABIS SATIVA L. WOODY CORE BY MEANS OF FT-IR SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    Esat Gümüşkaya

    2005-04-01

    Full Text Available In this study; it was investigated chemical compositions of hemp woody core and changes in crystallinity index of its carbohydrate components by using FT-IR spectroscopy was investigated. It was determined that carbohyrate components ratio in hemp woody core were similar to that in hard wood, but lignin content in hemp woody core was higher than in hard wood. Crystallinity index of carbohydrate components in hemp woody core increased by removing amorphous components. It was designated that monoclinic structure in hemp woody core and its carbohydrate components was dominant, but triclinic ratio increased by treated chemical isolation of carbohydrate from hemp woody core.

  6. Coarse Woody Debris Increases Microbial Community Functional Diversity but not Enzyme Activities in Reclaimed Oil Sands Soils.

    Science.gov (United States)

    Kwak, Jin-Hyeob; Chang, Scott X; Naeth, M Anne; Schaaf, Wolfgang

    2015-01-01

    Forest floor mineral soil mix (FMM) and peat mineral soil mix (PMM) are cover soils commonly used for upland reclamation post open-pit oil sands mining in northern Alberta, Canada. Coarse woody debris (CWD) can be used to regulate soil temperature and water content, to increase organic matter content, and to create microsites for the establishment of microorganisms and vegetation in upland reclamation. We studied the effects of CWD on soil microbial community level physiological profile (CLPP) and soil enzyme activities in FMM and PMM in a reclaimed landscape in the oil sands. This experiment was conducted with a 2 (FMM vs PMM) × 2 (near CWD vs away from CWD) factorial design with 6 replications. The study plots were established with Populus tremuloides (trembling aspen) CWD placed on each plot between November 2007 and February 2008. Soil samples were collected within 5 cm from CWD and more than 100 cm away from CWD in July, August and September 2013 and 2014. Microbial biomass was greater (pfunctional diversity (average well color development in Biolog Ecoplates) in both cover soils (pfunctional diversity by CWD application in upland reclamation has implications for accelerating upland reclamation after oil sands mining.

  7. Trace element accumulation in woody plants of the Guadiamar Valley, SW Spain: a large-scale phytomanagement case study.

    Science.gov (United States)

    Domínguez, María T; Marañón, Teodoro; Murillo, José M; Schulin, Rainer; Robinson, Brett H

    2008-03-01

    Phytomanagement employs vegetation and soil amendments to reduce the environmental risk posed by contaminated sites. We investigated the distribution of trace elements in soils and woody plants from a large phytomanaged site, the Guadiamar Valley (SW Spain), 7 years after a mine spill, which contaminated the area in 1998. At spill-affected sites, topsoils (0-25 cm) had elevated concentrations of As (129 mg kg(-1)), Bi (1.64 mg kg(-1)), Cd (1.44 mg kg(-1)), Cu (115 mg kg(-1)), Pb (210 mg kg(-1)), Sb (13.8 mg kg(-1)), Tl (1.17 mg kg(-1)) and Zn (457 mg kg(-1)). Trace element concentrations in the studied species were, on average, within the normal ranges for higher plants. An exception was white poplar (Populus alba), which accumulated Cd and Zn in leaves up to 3 and 410 mg kg(-1) respectively. We discuss the results with regard to the phytomanagement of trace element contaminated sites.

  8. Automated Multi-Peak Tracking Kymography (AMTraK: A Tool to Quantify Sub-Cellular Dynamics with Sub-Pixel Accuracy.

    Directory of Open Access Journals (Sweden)

    Anushree R Chaphalkar

    Full Text Available Kymographs or space-time plots are widely used in cell biology to reduce the dimensions of a time-series in microscopy for both qualitative and quantitative insight into spatio-temporal dynamics. While multiple tools for image kymography have been described before, quantification remains largely manual. Here, we describe a novel software tool for automated multi-peak tracking kymography (AMTraK, which uses peak information and distance minimization to track and automatically quantify kymographs, integrated in a GUI. The program takes fluorescence time-series data as an input and tracks contours in the kymographs based on intensity and gradient peaks. By integrating a branch-point detection method, it can be used to identify merging and splitting events of tracks, important in separation and coalescence events. In tests with synthetic images, we demonstrate sub-pixel positional accuracy of the program. We test the program by quantifying sub-cellular dynamics in rod-shaped bacteria, microtubule (MT transport and vesicle dynamics. A time-series of E. coli cell division with labeled nucleoid DNA is used to identify the time-point and rate at which the nucleoid segregates. The mean velocity of microtubule (MT gliding motility due to a recombinant kinesin motor is estimated as 0.5 μm/s, in agreement with published values, and comparable to estimates using software for nanometer precision filament-tracking. We proceed to employ AMTraK to analyze previously published time-series microscopy data where kymographs had been manually quantified: clathrin polymerization kinetics during vesicle formation and anterograde and retrograde transport in axons. AMTraK analysis not only reproduces the reported parameters, it also provides an objective and automated method for reproducible analysis of kymographs from in vitro and in vivo fluorescence microscopy time-series of sub-cellular dynamics.

  9. Automated Multi-Peak Tracking Kymography (AMTraK): A Tool to Quantify Sub-Cellular Dynamics with Sub-Pixel Accuracy.

    Science.gov (United States)

    Chaphalkar, Anushree R; Jain, Kunalika; Gangan, Manasi S; Athale, Chaitanya A

    2016-01-01

    Kymographs or space-time plots are widely used in cell biology to reduce the dimensions of a time-series in microscopy for both qualitative and quantitative insight into spatio-temporal dynamics. While multiple tools for image kymography have been described before, quantification remains largely manual. Here, we describe a novel software tool for automated multi-peak tracking kymography (AMTraK), which uses peak information and distance minimization to track and automatically quantify kymographs, integrated in a GUI. The program takes fluorescence time-series data as an input and tracks contours in the kymographs based on intensity and gradient peaks. By integrating a branch-point detection method, it can be used to identify merging and splitting events of tracks, important in separation and coalescence events. In tests with synthetic images, we demonstrate sub-pixel positional accuracy of the program. We test the program by quantifying sub-cellular dynamics in rod-shaped bacteria, microtubule (MT) transport and vesicle dynamics. A time-series of E. coli cell division with labeled nucleoid DNA is used to identify the time-point and rate at which the nucleoid segregates. The mean velocity of microtubule (MT) gliding motility due to a recombinant kinesin motor is estimated as 0.5 μm/s, in agreement with published values, and comparable to estimates using software for nanometer precision filament-tracking. We proceed to employ AMTraK to analyze previously published time-series microscopy data where kymographs had been manually quantified: clathrin polymerization kinetics during vesicle formation and anterograde and retrograde transport in axons. AMTraK analysis not only reproduces the reported parameters, it also provides an objective and automated method for reproducible analysis of kymographs from in vitro and in vivo fluorescence microscopy time-series of sub-cellular dynamics.

  10. A possible approach for gel-based proteomic studies in recalcitrant woody plants.

    Science.gov (United States)

    Sebastiana, Mónica; Figueiredo, Andreia; Monteiro, Filipa; Martins, Joana; Franco, Catarina; Coelho, Ana Varela; Vaz, Fátima; Simões, Tânia; Penque, Deborah; Pais, Maria Salomé; Ferreira, Sílvia

    2013-12-01

    Woody plants are particularly difficult to investigate due to high phenolic, resin, and tannin contents and laborious sample preparation. In particular, protein isolation from woody plants for two-dimensional gel electrophoresis (2-DE) is challenging as secondary metabolites negatively interfere with protein extraction and separation. In this study, three protein extraction protocols, using TCA, phenol and ethanol as precipitation or extraction agents, were tested in order to select the more efficient for woody recalcitrant plant gel-based proteomics. Grapevine leaves, pine needles and cork oak ectomycorrhizal roots were used to represent woody plant species and tissues. The phenol protocol produced higher quality 2-DE gels, with increased number of resolved spots, better spot focusing and representation of all molecular mass and isoelectric point ranges tested. In order to test the compatibility of the phenol extracted proteomes with protein identification several spots were excised from the phenol gels and analyzed by mass spectrometry (MALDI-TOF/TOF). Regardless the incomplete genome/protein databases for the plant species under analysis, 49 proteins were identified by Peptide Mass Fingerprint (PMF). Proteomic data have been deposited to the ProteomeXchange with identifier PXD000224. Our results demonstrate the complexity of protein extraction from woody plant tissues and the suitability of the phenol protocol for obtaining high quality protein extracts for efficient 2-DE separation and downstream applications such as protein identification by mass spectrometry.

  11. Comparative genomics reveals genes significantly associated with woody hosts in the plant pathogen Pseudomonas syringae.

    Science.gov (United States)

    Nowell, Reuben W; Laue, Bridget E; Sharp, Paul M; Green, Sarah

    2016-12-01

    The diversification of lineages within Pseudomonas syringae has involved a number of adaptive shifts from herbaceous hosts onto various species of tree, resulting in the emergence of highly destructive diseases such as bacterial canker of kiwi and bleeding canker of horse chestnut. This diversification has involved a high level of gene gain and loss, and these processes are likely to play major roles in the adaptation of individual lineages onto their host plants. In order to better understand the evolution of P. syringae onto woody plants, we have generated de novo genome sequences for 26 strains from the P. syringae species complex that are pathogenic on a range of woody species, and have looked for statistically significant associations between gene presence and host type (i.e. woody or herbaceous) across a phylogeny of 64 strains. We have found evidence for a common set of genes associated with strains that are able to colonize woody plants, suggesting that divergent lineages have acquired similarities in genome composition that may form the genetic basis of their adaptation to woody hosts. We also describe in detail the gain, loss and rearrangement of specific loci that may be functionally important in facilitating this adaptive shift. Overall, our analyses allow for a greater understanding of how gene gain and loss may contribute to adaptation in P. syringae. © 2016 The Authors. Molecular Plant Pathology published by British Society for Plant Pathology and John Wiley & Sons Ltd.

  12. Foliar and woody materials discriminated using terrestrial LiDAR in a mixed natural forest

    Science.gov (United States)

    Zhu, Xi; Skidmore, Andrew K.; Darvishzadeh, Roshanak; Niemann, K. Olaf; Liu, Jing; Shi, Yifang; Wang, Tiejun

    2018-02-01

    Separation of foliar and woody materials using remotely sensed data is crucial for the accurate estimation of leaf area index (LAI) and woody biomass across forest stands. In this paper, we present a new method to accurately separate foliar and woody materials using terrestrial LiDAR point clouds obtained from ten test sites in a mixed forest in Bavarian Forest National Park, Germany. Firstly, we applied and compared an adaptive radius near-neighbor search algorithm with a fixed radius near-neighbor search method in order to obtain both radiometric and geometric features derived from terrestrial LiDAR point clouds. Secondly, we used a random forest machine learning algorithm to classify foliar and woody materials and examined the impact of understory and slope on the classification accuracy. An average overall accuracy of 84.4% (Kappa = 0.75) was achieved across all experimental plots. The adaptive radius near-neighbor search method outperformed the fixed radius near-neighbor search method. The classification accuracy was significantly higher when the combination of both radiometric and geometric features was utilized. The analysis showed that increasing slope and understory coverage had a significant negative effect on the overall classification accuracy. Our results suggest that the utilization of the adaptive radius near-neighbor search method coupling both radiometric and geometric features has the potential to accurately discriminate foliar and woody materials from terrestrial LiDAR data in a mixed natural forest.

  13. The Role of Woodiness Mapping in the System of Adaptive and Landscape Arrangement of Catchments

    Directory of Open Access Journals (Sweden)

    Kosheleva Olga Yuryevna

    2015-04-01

    Full Text Available The article shows the results of agroforestry mapping of a Dobrinka basin catchment, which is located in the Volgograd region. The mapping is made on the basis of a high-resolution space images interpretation. Dobrinka river is the left inflow of the Medveditsa river, it belongs to the basin of Don. The length of the river makes about 36 km, the area of a catchment basin – 455,3 km2. The author applies the method of isoline mapping of woodiness, which allows receiving the average background surface transferring the largest regularities of spatial placement of forest plantings within a catchment. The author evaluates the features of spatial localization of natural and artificial plantings in the borders of Dobrinka catchment according to the isolinear maps of woodiness. The author establishes that there are two areas with the maximum values of natural woodiness within Dobrinka catchment, which are located in the floodplain forest of estuarial part of the basin and in ravine forest of upper part of Dobrinka river. The artificial woodiness within the whole catchment is very low and does not exceed 5 %. The existence in the central part of the catchment of an area with low indicators of natural and artificial woodiness contributes to the necessary development of the agroforestry arrangement project for this part of a basin catchment. The presented technique allows conducting the preliminary estimate of agroforestry arrangement of the catchments territory without financial expenses on reconnaissance.

  14. Disentangling the drivers of coarse woody debris behavior and carbon gas emissions during fire

    Science.gov (United States)

    Zhao, Weiwei; van der Werf, Guido R.; van Logtestijn, Richard S. P.; van Hal, Jurgen R.; Cornelissen, Johannes H. C.

    2016-04-01

    The turnover of coarse woody debris, a key terrestrial carbon pool, plays fundamental roles in global carbon cycling. Biological decomposition and fire are two main fates for dead wood turnover. Compared to slow decomposition, fire rapidly transfers organic carbon from the earth surface to the atmosphere. Both a-biotic environmental factors and biotic wood properties determine coarse wood combustion and thereby its carbon gas emissions during fire. Moisture is a key inhibitory environmental factor for fire. The properties of dead wood strongly affect how it burns either directly or indirectly through interacting with moisture. Coarse wood properties vary between plant species and between various decay stages. Moreover, if we put a piece of dead wood in the context of a forest fuel bed, the soil and wood contact might also greatly affect their fire behavior. Using controlled laboratory burns, we disentangled the effects of all these driving factors: tree species (one gymnosperms needle-leaf species, three angiosperms broad-leaf species), wood decay stages (freshly dead, middle decayed, very strongly decayed), moisture content (air-dried, 30% moisture content in mass), and soil-wood contact (on versus 3cm above the ground surface) on dead wood flammability and carbon gas efflux (CO2 and CO released in grams) during fire. Wood density was measured for all coarse wood samples used in our experiment. We found that compared to other drivers, wood decay stages have predominant positive effects on coarse wood combustion (for wood mass burned, R2=0.72 when air-dried and R2=0.52 at 30% moisture content) and associated carbon gas emissions (for CO2andCO (g) released, R2=0.55 when air-dried and R2=0.42 at 30% moisture content) during fire. Thus, wood decay accelerates wood combustion and its CO2 and CO emissions during fire, which can be mainly attributed to the decreasing wood density (for wood mass burned, R2=0.91 when air-dried and R2=0.63 at 30% moisture content) as wood

  15. Responses of woody species to spatial and temporal ground water changes in coastal sand dune systems

    Directory of Open Access Journals (Sweden)

    C. Máguas

    2011-12-01

    Full Text Available In spite of the relative importance of groundwater in costal dune systems, studies concerning the responses of vegetation to ground water (GW availability variations, particularly in Mediterranean regions, are scarce. Thus, the main purpose of this study is to compare the responses of co-occurring species possessing different functional traits, to changes in GW levels (i.e. the lowering of GW levels in a sand dune ecosystem. For that, five sites were established within a 1 km2 area in a meso-mediterranean sand dune ecosystem dominated by a Pinus pinaster forest. Due to natural topographic variability and anthropogenic GW exploitation, substantial variability in depth to GW between sites was found. Under these conditions it was possible to identify the degree of usage and dependence on GW of different plant species (two deep-rooted trees, a drought adapted shrub, a phreatophyte and a non-native woody invader and how GW dependence varied seasonally and between the heterogeneous sites. Results indicated that the plant species had differential responses to changes in GW depth according to specific functional traits (i.e. rooting depth, leaf morphology, and water use strategy. Species comparison revealed that variability in pre-dawn water potential (Ψpre and bulk leaf δ13C was related to site differences in GW use in the deep-rooted (Pinus pinaster, Myrica faya and phreatophyte (Salix repens species. However, such variation was more evident during spring than during summer drought. The exotic invader, Acacia longifolia, which does not possess a very deep root system, presented the largest seasonal variability in Ψpre and bulk leaf δ13C. In contrast, the response of Corema album, an endemic understory drought-adapted shrub, seemed to be independent of water availability across seasons and sites. Thus, the susceptibility to lowering of GW due to anthropogenic

  16. Responses of woody species to spatial and temporal ground water changes in coastal sand dune systems

    Science.gov (United States)

    Máguas, C.; Rascher, K. G.; Martins-Loução, A.; Carvalho, P.; Pinho, P.; Ramos, M.; Correia, O.; Werner, C.

    2011-12-01

    In spite of the relative importance of groundwater in costal dune systems, studies concerning the responses of vegetation to ground water (GW) availability variations, particularly in Mediterranean regions, are scarce. Thus, the main purpose of this study is to compare the responses of co-occurring species possessing different functional traits, to changes in GW levels (i.e. the lowering of GW levels) in a sand dune ecosystem. For that, five sites were established within a 1 km2 area in a meso-mediterranean sand dune ecosystem dominated by a Pinus pinaster forest. Due to natural topographic variability and anthropogenic GW exploitation, substantial variability in depth to GW between sites was found. Under these conditions it was possible to identify the degree of usage and dependence on GW of different plant species (two deep-rooted trees, a drought adapted shrub, a phreatophyte and a non-native woody invader) and how GW dependence varied seasonally and between the heterogeneous sites. Results indicated that the plant species had differential responses to changes in GW depth according to specific functional traits (i.e. rooting depth, leaf morphology, and water use strategy). Species comparison revealed that variability in pre-dawn water potential (Ψpre) and bulk leaf δ13C was related to site differences in GW use in the deep-rooted (Pinus pinaster, Myrica faya) and phreatophyte (Salix repens) species. However, such variation was more evident during spring than during summer drought. The exotic invader, Acacia longifolia, which does not possess a very deep root system, presented the largest seasonal variability in Ψpre and bulk leaf δ13C. In contrast, the response of Corema album, an endemic understory drought-adapted shrub, seemed to be independent of water availability across seasons and sites. Thus, the susceptibility to lowering of GW due to anthropogenic exploitation, in plant species from sand dunes, is variable, being particularly relevant for deep

  17. Woody plant richness and NDVI response to drought events in Catalonian (northeastern Spain) forests.

    Science.gov (United States)

    Lloret, F; Lobo, A; Estevan, H; Maisongrande, P; Vayreda, J; Terradas, J

    2007-09-01

    The role of species diversity on ecosystem resistance in the face of strong environmental fluctuations has been addressed from both theoretical and experimental viewpoints to reveal a variety of positive and negative relationships. Here we explore empirically the relationship between the richness of forest woody species and canopy resistance to extreme drought episodes. We compare richness data from an extensive forest inventory to a temporal series of satellite imagery that estimated drought impact on forest canopy as NDVI (normalized difference vegetation index) anomalies of the dry summer in 2003 in relation to records of previous years. We considered five different types of forests that are representative of the main climatic and altitudinal gradients of the region, ranging from lowland Mediterranean to mountain boreal-temperate climates. The observed relationship differed among forest types and interacted with the climate, summarised by the Thorntwaite index. In Mediterranean Pinus halepensis forests, NDVI decreased during the drought. This decrease was stronger in forests with lower richness. In Mediterranean evergreen forests of Quercus ilex, drought did not result in an overall NDVI loss, but lower NDVI values were observed in drier localities with lower richness, and in more moist localities with higher number of species. In mountain Pinus sylvestris forests NDVI decreased, mostly due to the drought impact on drier localities, while no relation to species richness was observed. In moist Fagus sylvatica forests, NDVI only decreased in plots with high richness. No effect of drought was observed in the high mountain Pinus uncinata forests. Our results show that a shift on the diversity-stability relationship appears across the regional, climatic gradient. A positive relationship appears in drier localities, supporting a null model where the probability of finding a species able to cope with drier conditions increases with the number of species. However, in

  18. On the measure of large woody debris in an alpine catchment

    Science.gov (United States)

    D'Agostino, V.; Bertoldi, G.; Rigon, E.

    2012-04-01

    The management of large woody debris (LWD) in Alpine torrents is a complex and ambiguous task. On one side the presence of LWD contributes to in-channel and floodplain morphological processes and plays an important role in landscape ecology and biodiversity. On the other side LWD increases considerably flood hazards when some river cross-sections result critical for the human interface (e.g. culverts, bridges, artificial channels). Only few studies provide quantitative data of LWD volumes in Alpine torrents. Research is needed both at basin scale processes (LWD recruiting from hillslopes) and at channel scale processes (feeding from river bank, storage/transport/deposition of LWD along the river bed). Our study proposes an integrate field survey methodology to assess the overall LWD amount which can be entrained by a flood. This knowledge is mandatory for the scientific research, for the implementation of LWD transport models, and for a complete hazard management in mountain basins. The study site is the high-relief basin of the Cordevole torrent (Belluno Province, Central Alps, Italy) whose outlet is located at the Saviner village (basin area of 109 square kilometers). In the November 1966 an extreme flood event occurred and some torrent reaches were heavily congested by LWD enhancing the overall damages due to long-duration overflows. Currently, the LWD recruitment seems to be strictly correlated with bank erosion and hillslope instability and the conditions of forest stand suggest LWD hazard is still high. Previous studies on sub-catchments of the Cordevole torrent have also shown an inverse relation between the drainage area and the LWD storage in the river-bed. Present contribution analyzes and quantifies the presence of LWD in the main valley channel of the Cordevole basin. A new sampling methodology was applied to integrate surveys of riparian vegetation and LWD storage. Data inventory confirms the previous relationship between LWD volumes and drainage area

  19. Regenerating Longleaf Pine on Hydric Soils: Short- and Long-term Effects on Native Ground-Layer Vegetation

    Science.gov (United States)

    2009-06-16

    herb astsp. Carphephorus odoratissimus vanilla leaf forb/herb carodo Carphephorus spp. chaffhead forb/herb carsp. Carphephorus tomentosus...form SYMBOL ANGIOSPERMS ROSACEAE Photinia pyrifolia red chokeberry woody/woody phopyr DICOTS Rubus spp. blackberry woody/woody rubsp

  20. Volatile organic emissions from the distillation and pyrolysis of vegetation

    Directory of Open Access Journals (Sweden)

    J. P. Greenberg

    2006-01-01

    Full Text Available Leaf and woody plant tissue (Pinus ponderosa, Eucalyptus saligna, Quercus gambelli, Saccharum officinarum and Oriza sativa were heated from 30 to 300°C and volatile organic compound (VOC emissions were identified and quantified. Major VOC emissions were mostly oxygenated and included acetic acid, furylaldehyde, acetol, pyrazine, terpenes, 2,3-butadione, phenol and methanol, as well as smaller emissions of furan, acetone, acetaldehyde, acetonitrile and benzaldehyde. Total VOC emissions from distillation and pyrolysis were on the order of 10 gC/kgC dry weight of vegetation, as much as 33% and 44% of CO2 emissions (gC(VOC/gC(CO2 measured during the same experiments, in air and nitrogen atmospheres, respectively. The emissions are similar in identity and quantity to those from smoldering combustion of woody tissue and of different character than those evolved during flaming combustion. VOC emissions from the distillation of pools and endothermic pyrolysis under low turbulence conditions may produce flammable concentrations near leaves and may facilitate the propagation of wildfires. VOC emissions from charcoal production are also related to distillation and pyrolysis; the emissions of the highly reactive VOCs from production are as large as the carbon monoxide emissions.

  1. Effects of vegetation heterogeneity and surface topography on spatial scaling of net primary productivity

    Science.gov (United States)

    Chen, J. M.; Chen, X.; Ju, W.

    2013-07-01

    Due to the heterogeneous nature of the land surface, spatial scaling is an inevitable issue in the development of land models coupled with low-resolution Earth system models (ESMs) for predicting land-atmosphere interactions and carbon-climate feedbacks. In this study, a simple spatial scaling algorithm is developed to correct errors in net primary productivity (NPP) estimates made at a coarse spatial resolution based on sub-pixel information of vegetation heterogeneity and surface topography. An eco-hydrological model BEPS-TerrainLab, which considers both vegetation and topographical effects on the vertical and lateral water flows and the carbon cycle, is used to simulate NPP at 30 m and 1 km resolutions for a 5700 km2 watershed with an elevation range from 518 m to 3767 m in the Qinling Mountain, Shanxi Province, China. Assuming that the NPP simulated at 30 m resolution represents the reality and that at 1 km resolution is subject to errors due to sub-pixel heterogeneity, a spatial scaling index (SSI) is developed to correct the coarse resolution NPP values pixel by pixel. The agreement between the NPP values at these two resolutions is improved considerably from R2 = 0.782 to R2 = 0.884 after the correction. The mean bias error (MBE) in NPP modelled at the 1 km resolution is reduced from 14.8 g C m-2 yr-1 to 4.8 g C m-2 yr-1 in comparison with NPP modelled at 30 m resolution, where the mean NPP is 668 g C m-2 yr-1. The range of spatial variations of NPP at 30 m resolution is larger than that at 1 km resolution. Land cover fraction is the most important vegetation factor to be considered in NPP spatial scaling, and slope is the most important topographical factor for NPP spatial scaling especially in mountainous areas, because of its influence on the lateral water redistribution, affecting water table, soil moisture and plant growth. Other factors including leaf area index (LAI) and elevation have small and additive effects on improving the spatial scaling

  2. Effects of vegetation heterogeneity and surface topography on spatial scaling of net primary productivity

    Directory of Open Access Journals (Sweden)

    J. M. Chen

    2013-07-01

    Full Text Available Due to the heterogeneous nature of the land surface, spatial scaling is an inevitable issue in the development of land models coupled with low-resolution Earth system models (ESMs for predicting land-atmosphere interactions and carbon-climate feedbacks. In this study, a simple spatial scaling algorithm is developed to correct errors in net primary productivity (NPP estimates made at a coarse spatial resolution based on sub-pixel information of vegetation heterogeneity and surface topography. An eco-hydrological model BEPS-TerrainLab, which considers both vegetation and topographical effects on the vertical and lateral water flows and the carbon cycle, is used to simulate NPP at 30 m and 1 km resolutions for a 5700 km2 watershed with an elevation range from 518 m to 3767 m in the Qinling Mountain, Shanxi Province, China. Assuming that the NPP simulated at 30 m resolution represents the reality and that at 1 km resolution is subject to errors due to sub-pixel heterogeneity, a spatial scaling index (SSI is developed to correct the coarse resolution NPP values pixel by pixel. The agreement between the NPP values at these two resolutions is improved considerably from R2 = 0.782 to R2 = 0.884 after the correction. The mean bias error (MBE in NPP modelled at the 1 km resolution is reduced from 14.8 g C m−2 yr−1 to 4.8 g C m−2 yr−1 in comparison with NPP modelled at 30 m resolution, where the mean NPP is 668 g C m−2 yr−1. The range of spatial variations of NPP at 30 m resolution is larger than that at 1 km resolution. Land cover fraction is the most important vegetation factor to be considered in NPP spatial scaling, and slope is the most important topographical factor for NPP spatial scaling especially in mountainous areas, because of its influence on the lateral water redistribution, affecting water table, soil moisture and plant growth. Other factors including leaf area index (LAI and elevation have small and additive effects on improving

  3. Soil and vegetation surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, E.J.

    1995-06-01

    Soil sampling and analysis evaluates long-term contamination trends and monitors environmental radionuclide inventories. This section of the 1994 Hanford Site Environmental Report summarizes the soil and vegetation surveillance programs which were conducted during 1994. Vegetation surveillance is conducted offsite to monitor atmospheric deposition of radioactive materials in areas not under cultivation and onsite at locations adjacent to potential sources of radioactivity.

  4. Woody plant diversity in sacred forests and fallows in Chiang Mai, Thailand

    DEFF Research Database (Denmark)

    Junsongduang, A.; Balslev, Henrik; Jampeetong, Arunothai

    2014-01-01

    All woody plant and seedling diversity was compared in a Karen and a Lawa hill-tribe village in northern Thailand in four different habitats: sacred forests and fallow fields of three ages derived from rotational shifting cultivation (young fallows, 1–2 years old; medium-age fallow, 3-4 years old......; old fallow, 5-6 years old). All woody plant species were identified and counted in three transects (20 x 40 m) . Seedlings were inventoried in 12 circular (5 m diam.) plots. The highest species richness of all woody species and seedlings were found in the sacred forests in both villages. The highest...... values of the Shannon-Wiener index for both trees and seedlings were in the sacred forest of the Karen village. There were significant differences in species richness between the four studied habitats surrounding both villages (pwoody plant and seedlings species compositions in the sacred...

  5. Relative role of contemporary environment versus history in shaping diversity patterns of China's woody plants

    DEFF Research Database (Denmark)

    Wang, Zhiheng; Fang, Jingyun; Tang, Zhiyao

    2012-01-01

    What determines large-scale patterns of species diversity is a central and controversial topic in biogeography and ecology. In this study, we compared the effects of contemporary environment and historical contingencies on species richness patterns of woody plants in China, using fine...... regions combined. This suggests different richness-environment relationships among regions. These results indicate important historical signals in the species richness patterns of woody plants across China. The signals are especially pronounced in the eastern Himalayas, the Mongolian Plateau......, and the Tibetan Plateau, perhaps reflecting their special geological features and history. Nevertheless, partial regression indicated that historical effects were less important relative to contemporary environment. In conclusion, contemporary environment (notably climate) determines the general trend in woody-plant...

  6. Genetic engineering of woody plants: current and future targets in a stressful environment.

    Science.gov (United States)

    Osakabe, Yuriko; Kajita, Shinya; Osakabe, Keishi

    2011-06-01

    Abiotic stress is a major factor in limiting plant growth and productivity. Environmental degradation, such as drought and salinity stresses, will become more severe and widespread in the world. To overcome severe environmental stress, plant biotechnologies, such as genetic engineering in woody plants, need to be implemented. The adaptation of plants to environmental stress is controlled by cascades of molecular networks including cross-talk with other stress signaling mechanisms. The present review focuses on recent studies concerning genetic engineering in woody plants for the improvement of the abiotic stress responses. Furthermore, it highlights the recent advances in the understanding of molecular responses to stress. The review also summarizes the basis of a molecular mechanism for cell wall biosynthesis and the plant hormone responses to regulate tree growth and biomass in woody plants. This would facilitate better understanding of the control programs of biomass production under stressful conditions. Copyright © Physiologia Plantarum 2011.

  7. Effect of removal of hesperis matronalis (Dame's rocket) on species cover of forest understory vegetation in NW indiana

    Science.gov (United States)

    Pavlovic, N.B.; Leicht-Young, S. A.; Frohnapple, K.J.; Grundel, R.

    2009-01-01

    Exotic invasive plant species differ in their effects on indigenous vegetation as evidenced by research evaluating community response to their removal. We used a removal approach to quantify the response of a mesic woodland to the removal versus retention of an invasive plant, Hesperis matronalis (dame's rocket) from paired treatment plots over 3 y. Cover of H. matronalis did not differ between control and treatment plots prior to removal, declined in the removal plots and remained significantly lower in cover compared to the control plots. Removal did not significantly affect species richness and species diversity (evenness, Shannon and Simpson) at the plot scale, but did result in increased species richness overall in the removal plots in the last sampling year when compared to control plots. Non-metric multidimensional scaling ordination analysis indicated a significant compositional change in the spring plant composition of plots over the 3 y, reflecting an increase in exotic woody species. Exotic woody plants, especially Rosa multiflora and Euonymus alatus, increased in cover in response to H. matronalis removal. In the 3 y, neither native nor exotic forbs, nor native woody plants responded to the removal of H. matronalis in a statistically significant manner. The increasing cover of woody invasive plants in response to the removal of H. matronalis has important management implications for restoration of degraded communities.

  8. Woody biomass comminution and sorting - a review of mechanical methods

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Gunnar [Swedish Univ. of Agricultural Sciences, Dept. of Forest Resource Management, Umeaa (Sweden)], e-mail: gunnar.eriksson@slu.se

    2012-11-01

    The increased demand for woody biomass for heat and electricity and biorefineries means that each bio component must be used efficiently. Any increase in raw material supply in the short term is likely to require the use of trees from early thinnings, logging residues and stumps, assortments of low value compared to stemwood. However, sorting of the novel materials into bio components may increase their value considerably. The challenge is to 1) maximise the overall values of the different raw material fractions for different users, 2) minimise costs for raw material extraction, processing, storage and transportation. Comminution of the raw material (e.g. to chips, chunks, flakes and powder) and sorting the bio components (e.g. separating bark from pulp chips and separating alkali-rich needles and shots for combustion and gasification applications) are crucial processes in this optimisation. The purpose of this study has been to make a literature review of principles for comminution and sorting, with an emphasis on mechanical methods suitable outside industries. More efficient comminution methods can be developed when the wood is to a larger extent cut along the fibre direction, and closer to the surface (with less pressure to the sides of the knife). By using coarse comminution (chunking) rather than fine comminution (chipping), productivity at landings can be increased and energy saved, the resulting product will have better storage and drying properties. At terminals, any further comminution (if necessary) could use larger-scale equipment of higher efficiency. Rolls and flails can be used to an increasing extent for removing foliage and twigs, possibly in the terrain (for instance fitted on grapples). Physical parameters used for sorting of the main components of trees include particle size, density and shape (aerodynamic drag and lift), optical and IR properties and X-ray fluorescence. Although methods developed for pulp chip production from whole trees may not

  9. Thermochemical pretreatment of underutilized woody biomass for manufacturing wood composites

    Science.gov (United States)

    Pelaez Samaniego, Manuel Raul

    Prescribed fires, one method for reducing hazardous fuel loads from forest lands in the US, are limited by geographical, environmental, and social impacts. Mechanical operations are an alternative type of fuel treatment but these processes are constrained by the difficulty of economically harvesting and/or using large amounts of low-value woody biomass. Adoption and integration of new technologies into existing wood composite facilities offer better utilization of this material. A pretreatment that enables integration of technologies in a typical composite facility will aid with diversification of product portfolio (e.g. wood composites, fuel pellets, liquid fuels, chemicals). Hot water extraction (HWE) is an option for wood pretreatment. This work provides a fundamental understanding of the physicochemical changes to wood resulting from HWE, and how these changes impact processing and performance of composites. Specific objectives were to: 1) review literature on studies related to the manufacture of composites produced with thermally pretreated wood, 2) manufacture wood plastic composites (WPC) and particleboard using HWE wood and evaluate the impacts of pretreatment on product properties, 3) develop an understanding of the effect of HWE on lignin properties, specifically lignin at the cells surface level after migration from cell walls and middle lamella, 4) discern the influence of lignin on the fiber surface on processing WPCs, and, 5) investigate the effect of changing the pretreatment environment (inert gas instead of water) on lignin behavior. Results show that HWE enhances the resistance of both WPCs and particleboard to water with positive or no effect on mechanical properties. Reduction of hemicelluloses and lignin property changes are suggested as the main reasons for enhancing interaction between wood fiber and resins during composite processing. Lignin on the surface of particles after HWE interacts with thermoplastics during WPCs compounding, thus

  10. Vegetation survey: a new focus for Applied Vegetation Science

    NARCIS (Netherlands)

    Chytry, M.; Schaminee, J.H.J.; Schwabe, A.

    2011-01-01

    Vegetation survey is an important research agenda in vegetation science. It defines vegetation types and helps understand differences among them, which is essential for both basic ecological research and applications in biodiversity conservation and environmental monitoring. In this editorial, we

  11. Woody plant richness does not influence invertebrate community reassembly trajectories in a tree diversity experiment.

    Science.gov (United States)

    Yeeles, Peter; Lach, Lori; Hobbs, Richard J; van Wees, Mary; Didham, Raphael K

    2017-02-01

    Understanding the relationship between plant diversity and diversity at higher trophic levels is important from both conservation and restoration perspectives. Although there is strong evidence for bottom-up maintenance of biodiversity, this is based largely on studies of simplified grassland systems. Recently, studies in the TreeDivNet global network of tree diversity experiments have begun to test whether these findings are generalizable to more complex ecosystems, such as woodlands. We monitored invertebrate community reassembly over 5 yr of experimental woodland restoration at the TreeDivNet Ridgefield site in southwest Australia, testing the effects of woody plant species richness and herb-layer manipulation on invertebrate community structure and ant species composition. From 2010 to 2014, we sampled ground-dwelling invertebrates using pitfall traps in herbicide vs. no-herbicide subplots nested within each of 10 woody plant treatments varying in richness from zero (bare controls) to eight species, which produced a total of 211, 235 invertebrates, including 98, 979 ants belonging to 74 species. In mixed model analyses, the presence of woody plants was an important driver of faunal community reassembly (relative to bare control plots), but faunal responses to woody plant treatment combinations were idiosyncratic and unrelated to woody plant richness across treatments. We also found that a herbicide-induced reduction in herbaceous plant cover and richness had a positive effect on ant richness and caused more rapid convergence of invertebrate community composition toward the composition of a woodland reference site. These findings show that woody plant richness did not have direct positive effects on the diversity and community reassembly trajectories of higher trophic levels in our woodland system. From a management perspective, this suggests that even low-diversity restoration or carbon sequestration plantings can potentially lead to faunal reassembly outcomes

  12. Coarse Woody Debris Increases Microbial Community Functional Diversity but not Enzyme Activities in Reclaimed Oil Sands Soils.

    Directory of Open Access Journals (Sweden)

    Jin-Hyeob Kwak

    Full Text Available Forest floor mineral soil mix (FMM and peat mineral soil mix (PMM are cover soils commonly used for upland reclamation post open-pit oil sands mining in northern Alberta, Canada. Coarse woody debris (CWD can be used to regulate soil temperature and water content, to increase organic matter content, and to create microsites for the establishment of microorganisms and vegetation in upland reclamation. We studied the effects of CWD on soil microbial community level physiological profile (CLPP and soil enzyme activities in FMM and PMM in a reclaimed landscape in the oil sands. This experiment was conducted with a 2 (FMM vs PMM × 2 (near CWD vs away from CWD factorial design with 6 replications. The study plots were established with Populus tremuloides (trembling aspen CWD placed on each plot between November 2007 and February 2008. Soil samples were collected within 5 cm from CWD and more than 100 cm away from CWD in July, August and September 2013 and 2014. Microbial biomass was greater (p<0.05 in FMM than in PMM, in July, and August 2013 and July 2014, and greater (p<0.05 near CWD than away from CWD in FMM in July and August samplings. Soil microbial CLPP differed between FMM and PMM (p<0.01 according to a principal component analysis and CWD changed microbial CLPP in FMM (p<0.05 but not in PMM. Coarse woody debris increased microbial community functional diversity (average well color development in Biolog Ecoplates in both cover soils (p<0.05 in August and September 2014. Carbon degrading soil enzyme activities were greater in FMM than in PMM (p<0.05 regardless of distance from CWD but were not affected by CWD. Greater microbial biomass and enzyme activities in FMM than in PMM will increase organic matter decomposition and nutrient cycling, improving plant growth. Enhanced microbial community functional diversity by CWD application in upland reclamation has implications for accelerating upland reclamation after oil sands mining.

  13. Soil-borne phytophtoras and woody plants in Saint-Petersburg: new threats of the third millennium

    Directory of Open Access Journals (Sweden)

    Firsov Gennadiy

    2014-12-01

    air and soil, the weakeaning of frosts, the prolongation of vegetative season, the rise of summer temperatures and the shortening of winter season with the diminishing of soil freezing have been contributing to distribution of Phytophthora species. In conditions of the climate changes the soil-borne phytophthoras constitute the considerable threat to woody plants of city parks and neigbouring forests around Saint-Petersburg.

  14. Coarse Woody Debris Increases Microbial Community Functional Diversity but not Enzyme Activities in Reclaimed Oil Sands Soils

    Science.gov (United States)

    Kwak, Jin-Hyeob; Chang, Scott X.; Naeth, M. Anne; Schaaf, Wolfgang

    2015-01-01

    Forest floor mineral soil mix (FMM) and peat mineral soil mix (PMM) are cover soils commonly used for upland reclamation post open-pit oil sands mining in northern Alberta, Canada. Coarse woody debris (CWD) can be used to regulate soil temperature and water content, to increase organic matter content, and to create microsites for the establishment of microorganisms and vegetation in upland reclamation. We studied the effects of CWD on soil microbial community level physiological profile (CLPP) and soil enzyme activities in FMM and PMM in a reclaimed landscape in the oil sands. This experiment was conducted with a 2 (FMM vs PMM) × 2 (near CWD vs away from CWD) factorial design with 6 replications. The study plots were established with Populus tremuloides (trembling aspen) CWD placed on each plot between November 2007 and February 2008. Soil samples were collected within 5 cm from CWD and more than 100 cm away from CWD in July, August and September 2013 and 2014. Microbial biomass was greater (p<0.05) in FMM than in PMM, in July, and August 2013 and July 2014, and greater (p<0.05) near CWD than away from CWD in FMM in July and August samplings. Soil microbial CLPP differed between FMM and PMM (p<0.01) according to a principal component analysis and CWD changed microbial CLPP in FMM (p<0.05) but not in PMM. Coarse woody debris increased microbial community functional diversity (average well color development in Biolog Ecoplates) in both cover soils (p<0.05) in August and September 2014. Carbon degrading soil enzyme activities were greater in FMM than in PMM (p<0.05) regardless of distance from CWD but were not affected by CWD. Greater microbial biomass and enzyme activities in FMM than in PMM will increase organic matter decomposition and nutrient cycling, improving plant growth. Enhanced microbial community functional diversity by CWD application in upland reclamation has implications for accelerating upland reclamation after oil sands mining. PMID:26618605

  15. A STELLA model to estimate water and nitrogen dynamics in a short-rotation woody crop plantation

    Science.gov (United States)

    Ying Ouyang; Jiaen Zhang; Theodor D. Leininger; Brent R. Frey

    2015-01-01

    Although short-rotation woody crop biomass production technology has demonstrated a promising potential to supply feedstocks for bioenergy production, the water and nutrient processes in the woody crop planation ecosystem are poorly understood. In this study, a computer model was developed to estimate the dynamics of water and nitrogen (N) species (e.g., NH4...

  16. First steps in studying the origins of secondary woodiness in Begonia (Begoniaceae): combining anatomy, phylogenetics, and stem transcriptomics

    Science.gov (United States)

    Catherine Kidner; Andrew Groover; Daniel C. Thomas; Katie Emelianova; Claudia Soliz-Gamboa; Frederic Lens

    2015-01-01

    Since Darwin's observation that secondary woodiness is common on islands, the evolution of woody plants from herbaceous ancestors has been documented in numerous angiosperm groups. However, the evolutionary processes that give rise to this phenomenon are poorly understood. To begin addressing this we have used a range of approaches to study the anatomical and...

  17. Assessing Extension's Ability to Promote Family Forests as a Woody Biomass Feedstock in the Northeast United States

    Science.gov (United States)

    Germain, Rene' H.; Ghosh, Chandrani

    2013-01-01

    The study reported here surveyed Extension educators' awareness and knowledge of woody biomass energy and assessed their desire and ability to reach out to family forest owners-a critical feedstock source. The results indicate Extension educators are aware of the potential of woody biomass to serve as a renewable source of energy. Respondents…

  18. Wood and coal cofiring in interior Alaska: utilizing woody biomass from wildland defensible-space fire treatments and other sources.

    Science.gov (United States)

    David L. Nicholls; Stephen E. Patterson; Erin. Uloth

    2006-01-01

    Cofiring wood and coal at Fairbanks, Alaska, area electrical generation facilities represents an opportunity to use woody biomass from clearings within the borough's wildland-urban interface and from other sources, such as sawmill residues and woody material intended for landfills. Potential benefits of cofiring include air quality improvements, reduced greenhouse...

  19. Long-term effects of burning on woody plant species sprouting on the False thornveld of Eastern Cape

    CSIR Research Space (South Africa)

    Ratsele, C

    2010-11-01

    Full Text Available Sprouting allows woody plant species to persist in a site after a wide range of disturbances (e.g. prolonged fire), where opportunities for seedling establishment are limited. A study to investigate long-term effects of fire sprouting of woody...

  20. Assessing the Roles of Fire Frequency and Precipitation in Determining Woody Plant Expansion in Central U.S. Grasslands

    Science.gov (United States)

    Brunsell, N. A.; Van Vleck, E. S.; Nosshi, M.; Ratajczak, Z.; Nippert, J. B.

    2017-10-01

    Woody plant expansion into grasslands and savannas is occurring and accelerating worldwide and often impacts ecosystem processes. Understanding and predicting the environmental and ecological impacts of encroachment has led to a variety of methodologies for assessing its onset, transition, and stability, generally relying on dynamical systems approaches. Here we continue this general line of investigation to facilitate the understanding of the roles of precipitation frequency and intensity and fire frequency on the conversion of grasslands to woody-dominated systems focusing on the central United States. A low-dimensional model with stochastic precipitation and fire disturbance is introduced to examine the complex interactions between precipitation and fire as mechanisms that may suppress or facilitate increases in woody cover. By using Lyapunov exponents, we are able to ascertain the relative control exerted on woody encroachment through these mechanisms. Our results indicate that precipitation frequency is a more important control on woody encroachment than the intensity of individual precipitation events. Fire, however, exerts a much more dominant impact on the limitation of encroachment over the range of precipitation variability considered here. These results indicate that fire management may be an effective strategy to slow the onset of woody species into grasslands. While climate change might predict a reduced potential for woody encroachment in the near future, these results indicate a reduction in woody fraction may be unlikely when considering anthropogenic fire suppression.