Woody vegetation provides a number of ecosystem services, including soil protection, carbon sequestration and oxygen production. Despite its important role in maintaining ecological balance, woody vegetation is curren...Woody vegetation provides a number of ecosystem services, including soil protection, carbon sequestration and oxygen production. Despite its important role in maintaining ecological balance, woody vegetation is currently undergoing continuous degradation due to climatic hazards and anthropogenic actions. As a result, it is essential to gather information for the sustainable and rational management of woody formations. It is with this in mind that this study aims to contribute to a better understanding of the state of woody vegetation in the different land-use types in Basse Casamance. To this end, stratified random sampling of woody vegetation was carried out in the different land-use types (fields, fallow land and forests) of the Coubalan commune. The sampling unit for fields and fallows was a 2500 m<sup>2</sup> plot, and for forests was a 900 m<sup>2</sup> plot. A total of 53 species, divided into 48 genera belonging to 22 families, were inventoried in the commune. Structural parameters were higher in the forest, with 1321.3 ± 635.8 individuals/ha, 13.09 ± 0.1 m<sup>2</sup> and 79.25% ± 21.08% respectively for observed density, basal area and cover rate. As for dendrometric parameters, they are higher in the fields, with 20.4 ± 13.6 cm and 7.4 ± 3.8 m respectively for trunk diameter and woody height. Fallow land is characterized by species with low dendrometric parameters. These results provide a useful database for rational management of the various land-use types in the commune of Coubalan.展开更多
Like several Sahelian countries, Senegal is facing a strong degradation of woody and arable resources. This is due to the development of certain inappropriate agricultural practices. To mitigate this situation, the po...Like several Sahelian countries, Senegal is facing a strong degradation of woody and arable resources. This is due to the development of certain inappropriate agricultural practices. To mitigate this situation, the populations tend to preserve and maintain certain woody species of interest in the fields, thus constituting agroforestry parks. Thus, the objective of this study was to contribute to a better understanding of the characteristics of woody vegetation in agroforestry parks in the department of Bignona. To this end, a plot of 2500 m<sup>2</sup> (50 m × 50 m) was installed in the fields of each farmer selected in a sample of 99 farm managers distributed in the three communes (Djinaky, Kataba1 and Kafountine) of the Kataba1 district, for a total of 99 plots installed. A total of seventy-three (73) species divided into fifty-five (55) genera and twenty-eight (27) botanical families were inventoried. In the agroforestry parks of the Kataba 1 district, the density of woody vegetation is 56.12 individuals/ha, the cover rate is 27.9% and the basal area is 5.9 m<sup>2</sup>/ha. The vertical structure of the woody vegetation is characterized by a predominance of individuals between 2 and 4 m in height (48.07%). As for the horizontal structure, it is characterized by a predominance of individuals of diameter between 5 and 20 cm (39.19%). These results obtained will serve as a source of information for better management of these agroforestry parks by the populations.展开更多
In this paper, based on the analysis of satellite measurements, the authors conclude that the continuous seasonal droughts intensify the browning of woody vegetation and that evergreen needleleaf forest(ENF) shows a l...In this paper, based on the analysis of satellite measurements, the authors conclude that the continuous seasonal droughts intensify the browning of woody vegetation and that evergreen needleleaf forest(ENF) shows a larger browning percentage than other woody vegetation types over Yunnan Province. Based on the Tropical Rainfall Measuring Mission(TRMM) precipitation standardized anomaly, in the dry season, which is from October to March, the 2010 drought affected an area of Yunnan Province 1.77 times larger than the 2012 drought, but in the post-drought months(April to June), the browning area of all woody vegetation in 2012 was 1.11 times larger than that in 2010 on the basis of the enhanced vegetation index(EVI) standardized anomaly. The reduction of vegetation greenness over large areas of Yunnan Province represents a photosynthetic capacity loss which will have an impact on carbon fluxes to the atmosphere.展开更多
Forest and non-forest vegetation fulfils many non-productive and productive functions. A good understanding of the trajectories and drivers of the woody vegetation change is necessary for the relevant management. Rece...Forest and non-forest vegetation fulfils many non-productive and productive functions. A good understanding of the trajectories and drivers of the woody vegetation change is necessary for the relevant management. Recently, the number of studies devoted to monitoring forest cover changes has increased. However, these works do not fully distinguish between different categories of forest and non-forest woody vegetation. The main aim of the study was to propose a classification system for monitoring historic changes of woody vegetation in the landscape. The period of the last 150 years was mapped through three time-lines (1842, 1953 and 2011). Data were obtained by interpreting historic maps (Stable Cadastral map of 1842) and historical (1953) and current orthophoto (2011) using ArcGIS tools. The classification was applied on the example of Sokolov region (57 km2) located in western Bohemia. The result of the research is a proposal for classifying woody vegetation stands into four categories based on the structural and localisation criteria: (1) Line adjacent woodlands, (2) Landscape woodlands, (3) Settlement woodlands, and (4) Compact woodlands. Information on the woody vegetation development using the proposed classification system is important for understanding the patterns, pressures, and driving forces that led to the formation of the present-day forest and non-forest woody vegetation in the landscape. The results can also be applied as a basis for future forest management practice as they can be used in other different fields, e.g. history, archaeology etc.展开更多
To reliably estimate water levels and velocities in vegetated rivers and floodplains, flow resistance models based on physical plant properties are advantageous. The purpose of this study is （1） to assess the suitab...To reliably estimate water levels and velocities in vegetated rivers and floodplains, flow resistance models based on physical plant properties are advantageous. The purpose of this study is （1） to assess the suitable parameterization of woody riparian vegetation in estimating the drag forces, （2） to address the effect of plant scale on the drag estimates and reconfiguration, and （3） to evaluate the applicability of three recently developed flow resistance models. Experiments on four tree species in a towing tank together with detailed characterization of tree properties were carried out to establish a novel dataset. Despite the variability in the tree height （0.9 m-3.4 m）, the stem, leaf and total areas proved to be suitable characteristic dimensions for estimating the flow resistance at different scales. Evaluations with independent data revealed that the tested models produced reasonable results. The performance of the models was controlled by the parameter values used rather than the model structure or the plant scale.展开更多
Communal rangelands provide diverse ecosystem services to millions of pastoralists and agro-pastoralists. Resettling destitute communities into hitherto uninhabited communal rangelands and forests, a common practice t...Communal rangelands provide diverse ecosystem services to millions of pastoralists and agro-pastoralists. Resettling destitute communities into hitherto uninhabited communal rangelands and forests, a common practice throughout Sub-Saharan Africa, is a threat to the sustainable use of range and forest land resources. In order to understand the effect of resettlement on a semi-arid woodland in northwestern Ethiopia, satellite imagery of 23 resettlement villages taken over a period of fourteen years, and woody vegetation floristic data for three old resettlements, three new resettlements, two refugee camps and one protected area were analyzed using ANOVA and canonical correspondence analysis（CCA）. The normalized differential vegetation index（NDVI） and canopy cover around all village types decreased with disturbance gradients, while the magnitude of change varied according to the type of settlement. Limited canopy cover was observed in refugee camps and new resettlements, compared to old resettlements and protected areas. Woody vegetation height class showed a J shaped distribution in all sites except refugee camps（RC）, indicating a decline in vegetation. CCA showed that variables like site type, altitude and disturbance gradient significantly affected the diversity of woody species at the different sites. Comparison of individual species responses to disturbances indicated that low fodder value invaders like Dichrostachys cinerea, and many Acacia species were increasing in proportion and coverage at the expense of some multipurpose species including Tamarindus indica, Diospyros mespiliformis, and Pterocarpus lucens. In the absence of regulated vegetation use, resettlements result in a decline in overall vegetation cover and a shift in floristic diversity in favor of invasive species.展开更多
Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies...Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only(Pisang site) while the other pair has clear differences in land use in addition to slope exposure(Braka site). In each site, we sampled 72 plots(36 on each slope) in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis(CA) results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables(e.g., radiation index) affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Braka. We conclude that slope orientation and land use are important factors in structuring the woody species composition and diversity in the arid Trans-Himalayan region. We suggest that both environmental and land use variables should be taken into consideration in future studies on plant community structure along the cultural landscapes.展开更多
The colonization and development of biological soil crusts （BSCs） are rarely discussed when investigating vegetation restoration with difference arrangement and structure of anthropogenically damaged areas in semi-a...The colonization and development of biological soil crusts （BSCs） are rarely discussed when investigating vegetation restoration with difference arrangement and structure of anthropogenically damaged areas in semi-arid regions. The present study analyzes the relationships among coverage, height and density of woody vegetation and coverage and thickness of BSCs on the surface mine dumpsite in Heidaigou, China. Results showed that PR （Prunus sibirica L.）, PT （Pinus tabulaeformis Carr.） and PPr （P. tabulaeformis Carr., P. sibirica L.） types had the highest coverage of total BSCs, which were 76.8%, 75.9% and 78.9%, respectively and PR showed the thickest BSCs of 4.41 mm. There was a significant correlation between coverage and thickness of BSCs and coverage and height of woody vegetation as a unimodal curve. Our findings suggest that a single woody plant species and low level coverage and height （no more than 30% and 300 cm, respectively） of woody plants may be able to create suitable conditions for facilitating BSCs restoration on the surface of mine dumpsites. The effects of vegetation arrangement and structure on BSCs colonization and development should be considered in reconstructing and managing woody vegetation in disturbed environments, such as surface mine dumpsites in semi-arid areas.展开更多
To investigate the woody species composition,diversity and structure of Kuandisha Afromontane forest,vegetation and environmental data were collected from 53 plots of 10 m 9 50 m for trees and shrubs and 265 subplots ...To investigate the woody species composition,diversity and structure of Kuandisha Afromontane forest,vegetation and environmental data were collected from 53 plots of 10 m 9 50 m for trees and shrubs and 265 subplots of 2 m 9 4 m for seedlings were laid along eight transect lines. The local name, scientific name, abundance,DBH, height and percentage foliage cover of species were recorded. Environmental variables, namely altitude, latitude and longitude as well as disturbance levels were also recorded in each plot. Structure, basal area, importance value index（IVI） and species prioritization were analyzed using spreadsheet programs. Correlation coefficients, frequency, relative frequency, Shannon diversity index,Shannon evenness and vegetation classification were analyzed using an R package. Sixty-six species belonging to40 families were recorded. Fabaceae was the most diverse family consisting of seven species, followed by Euphorbiaceae and Asteraceae. In terms of habit, 29 species were trees, 28 were shrubs, and 9 were lianas. The overall Shannon diversity index was 2.5. The frequency and relative frequency of woody species with DBH C2.5 cm ranged from 1.9 to 92.5 and 0.1 to 5, respectively. Seedling density varied among species ranging from five to 9938 individuals ha-1. The total basal area of woody species having DBH C2.5 cm is 15.3 m2ha-1. The IVI of species ranged from 0.13 for Solanum giganteum Jacq. to 28.4 for Croton macrostachyus Del. The woody vegetation was classified into five community types. Species richness,diversity and evenness of communities were strongly positively correlated. On the other hand, the correlation between disturbance and seedling density, and species richness was strongly negative. Thus, among the recorded woody species, a significant portion was either lacking regeneration or selectively removed for various purposes.The lack of seedlings of those species is mainly attributed to anthropogenic disturbances particularly free grazing. As a result, 14 tree, seven shrub and one liana species were prioritized for conservation and management interventions.展开更多
The present study assesses anthropogenic disturbances and their impacts on the vegetation in Western Himalaya,India on the basis of various disturbance parameters such as density,Total Basal Cover(TBC) of cut stumps,l...The present study assesses anthropogenic disturbances and their impacts on the vegetation in Western Himalaya,India on the basis of various disturbance parameters such as density,Total Basal Cover(TBC) of cut stumps,lopping percentage and grazing intensities.On the basis of canopy cover and frequency of disturbances(%),the studied forests were divided into highly disturbed(HD),moderately disturbed(MD) and least disturbed(LD) categories.The HD forests had the lowest canopy cover,lowest density and lowest TBC and the LD had the highest canopy cover,highest density and highest TBC.The MD forests occupied the intermediate position with respect to these parameters.Species richness was least in HD forests,highest in one of the MD forests while LD forest occupied an intermediate position.The percentage of regenerating species was lowest(54%) in HD and highest(72%) in MD.The density of seedlings and saplings was higher in one of the MD forests as compared to HD and LD.We concluded that the moderate disturbances do not affect the vegetation adversely;however the increased degree of disturbance causes loss in plant diversity;affects regeneration and changes community characteristics.Construction of hydroelectric projects at various places in the study area was found to be one of the most important sources of anthropogenic disturbances in addition to the routine anthropogenic disturbances like grazing,fuelwood collection and fodder extraction.If all proposed dams in the Indian Himalaya are constructed combined with weak national environmental impact assessment and implementation,it will result in a significant loss of species.Therefore,various agents of disturbances should be evaluated in cumulative manner and any developmental activities such as hydropower projects,which trigger various natural and anthropogenic disturbances,should be combined with proper cumulative environmental impact assessment and effective implementation to minimise the anticipated loss of vegetation.展开更多
Canopy gaps play a significant role in maintaining structure and composition of tropical forests. This study was carried out in tropical evergreen forests of central Western Ghats in India to understand the influence ...Canopy gaps play a significant role in maintaining structure and composition of tropical forests. This study was carried out in tropical evergreen forests of central Western Ghats in India to understand the influence of canopy gap size and the relationship of gap regime attributes to diversity measures and regeneration. The average gap size in the study area was found to be 396 m2 and around half of gaps were 4–8 years old. Gaps created by natural single tree fall were smaller in size but significantly higher in number. Diversity and regeneration of woody species were compared with canopy gaps and intact vegetation. Species richness and diversity was higher in gaps than in intact vegetation. Macaranga peltata, a shade intolerant species dominated gaps while intact vegetation was dominated by shade tolerant Kingiodendron pinnatum.Gap size significantly influenced species diversity and regeneration. Gap area and age were significantly and negatively correlated with diversity measures but positively correlated with regeneration. Among all the attributes of gaps, regeneration was significantly positively correlated with light intensity. Gaps maintained species diversity and favored regeneration of woody species. In addition to gap size and age, other gap ecological attributes also affected species diversity and regeneration.展开更多
Aims studies of species distribution patterns traditionally have been conducted at a single scale,often overlooking species-environment relationships operating at finer or coarser scales.Testing diversity-related hypo...Aims studies of species distribution patterns traditionally have been conducted at a single scale,often overlooking species-environment relationships operating at finer or coarser scales.Testing diversity-related hypotheses at multiple scales requires a robust sampling design that is nested across scales.our chief motivation in this study was to quantify the contributions of different predictors of herbaceous species richness at a range of local scales.Methods Here,we develop a hierarchically nested sampling design that is balanced across scales,in order to study the role of several envi-ronmental factors in determining herbaceous species distribution at various scales simultaneously.We focus on the impact of woody vegetation,a relatively unexplored factor,as well as that of soil and topography.light detection and ranging(liDAR)imaging enabled precise characterization of the 3D structure of the woody vegetation,while acoustic spectrophotometry allowed a particularly high-resolution mapping of soil CaCo3 and organic matter contents.Important Findings We found that woody vegetation was the dominant explanatory variable at all three scales(10,100 and 1000 m2),accounting for more than 60%of the total explained variance.in addition,we found that the species richness-environment relationship was scale dependent.many studies that explicitly address the issue of scale do so by comparing local and regional scales.our results show that efforts to conserve plant communities should take into account scale dependence when analyzing species richness-environment relationships,even at much finer resolutions than local vs.regional.in addition,conserving heterogeneity in woody vegetation structure at multiple scales is a key to conserving diverse herbaceous communities.展开更多
Introduction:Forests form a major component of the carbon(C)reserves in the world’s ecosystems.However,little is known on how management influences C stocks of woody vegetation,particularly in dry areas.We developed ...Introduction:Forests form a major component of the carbon(C)reserves in the world’s ecosystems.However,little is known on how management influences C stocks of woody vegetation,particularly in dry areas.We developed regression models for two dominant tree species to predict C stocks and quantified the potential of community managed forests as C sinks.Methods:Plots were randomly selected from community-managed natural forest,herbivore exclosures,and from communal grazing land.Tree and shrub biomass were estimated using a regression model on the most dominant woody species while herbaceous biomass was determined using destructive sampling.Results:The simplest model,based on only one single predictor variable,showed a good fit to the data for both species(Juniperus procera and Acacia abyssinica).Diameter at breast height(r2>0.95)was a more reliable predictor than height(r2>0.54),crown diameter(r2>0.68)(p<0.001).The C content of the total biomass for the managed natural forest and the exclosure were estimated as,58.11 and 22.29 Mg ha−1,respectively,while that for the grazing land was 7.76 Mg ha−1,and the mean carbon content between the three land uses were significantly different(p<0.05).Conclusions:We conclude that forests managed by the community have a high potential for C sequestration and storage and their conservation should be promoted.展开更多
文摘Woody vegetation provides a number of ecosystem services, including soil protection, carbon sequestration and oxygen production. Despite its important role in maintaining ecological balance, woody vegetation is currently undergoing continuous degradation due to climatic hazards and anthropogenic actions. As a result, it is essential to gather information for the sustainable and rational management of woody formations. It is with this in mind that this study aims to contribute to a better understanding of the state of woody vegetation in the different land-use types in Basse Casamance. To this end, stratified random sampling of woody vegetation was carried out in the different land-use types (fields, fallow land and forests) of the Coubalan commune. The sampling unit for fields and fallows was a 2500 m<sup>2</sup> plot, and for forests was a 900 m<sup>2</sup> plot. A total of 53 species, divided into 48 genera belonging to 22 families, were inventoried in the commune. Structural parameters were higher in the forest, with 1321.3 ± 635.8 individuals/ha, 13.09 ± 0.1 m<sup>2</sup> and 79.25% ± 21.08% respectively for observed density, basal area and cover rate. As for dendrometric parameters, they are higher in the fields, with 20.4 ± 13.6 cm and 7.4 ± 3.8 m respectively for trunk diameter and woody height. Fallow land is characterized by species with low dendrometric parameters. These results provide a useful database for rational management of the various land-use types in the commune of Coubalan.
文摘Like several Sahelian countries, Senegal is facing a strong degradation of woody and arable resources. This is due to the development of certain inappropriate agricultural practices. To mitigate this situation, the populations tend to preserve and maintain certain woody species of interest in the fields, thus constituting agroforestry parks. Thus, the objective of this study was to contribute to a better understanding of the characteristics of woody vegetation in agroforestry parks in the department of Bignona. To this end, a plot of 2500 m<sup>2</sup> (50 m × 50 m) was installed in the fields of each farmer selected in a sample of 99 farm managers distributed in the three communes (Djinaky, Kataba1 and Kafountine) of the Kataba1 district, for a total of 99 plots installed. A total of seventy-three (73) species divided into fifty-five (55) genera and twenty-eight (27) botanical families were inventoried. In the agroforestry parks of the Kataba 1 district, the density of woody vegetation is 56.12 individuals/ha, the cover rate is 27.9% and the basal area is 5.9 m<sup>2</sup>/ha. The vertical structure of the woody vegetation is characterized by a predominance of individuals between 2 and 4 m in height (48.07%). As for the horizontal structure, it is characterized by a predominance of individuals of diameter between 5 and 20 cm (39.19%). These results obtained will serve as a source of information for better management of these agroforestry parks by the populations.
基金funded by the National Basic Research Program of China (Grant No. 2012CB956202)the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA05090200)
文摘In this paper, based on the analysis of satellite measurements, the authors conclude that the continuous seasonal droughts intensify the browning of woody vegetation and that evergreen needleleaf forest(ENF) shows a larger browning percentage than other woody vegetation types over Yunnan Province. Based on the Tropical Rainfall Measuring Mission(TRMM) precipitation standardized anomaly, in the dry season, which is from October to March, the 2010 drought affected an area of Yunnan Province 1.77 times larger than the 2012 drought, but in the post-drought months(April to June), the browning area of all woody vegetation in 2012 was 1.11 times larger than that in 2010 on the basis of the enhanced vegetation index(EVI) standardized anomaly. The reduction of vegetation greenness over large areas of Yunnan Province represents a photosynthetic capacity loss which will have an impact on carbon fluxes to the atmosphere.
基金supported by Ministry of Agriculture of the Czech Republic,project No.CR QH 82106 Re-cultivation as a tool for landscape functionality regeneration after opencast brown coal mining.
文摘Forest and non-forest vegetation fulfils many non-productive and productive functions. A good understanding of the trajectories and drivers of the woody vegetation change is necessary for the relevant management. Recently, the number of studies devoted to monitoring forest cover changes has increased. However, these works do not fully distinguish between different categories of forest and non-forest woody vegetation. The main aim of the study was to propose a classification system for monitoring historic changes of woody vegetation in the landscape. The period of the last 150 years was mapped through three time-lines (1842, 1953 and 2011). Data were obtained by interpreting historic maps (Stable Cadastral map of 1842) and historical (1953) and current orthophoto (2011) using ArcGIS tools. The classification was applied on the example of Sokolov region (57 km2) located in western Bohemia. The result of the research is a proposal for classifying woody vegetation stands into four categories based on the structural and localisation criteria: (1) Line adjacent woodlands, (2) Landscape woodlands, (3) Settlement woodlands, and (4) Compact woodlands. Information on the woody vegetation development using the proposed classification system is important for understanding the patterns, pressures, and driving forces that led to the formation of the present-day forest and non-forest woody vegetation in the landscape. The results can also be applied as a basis for future forest management practice as they can be used in other different fields, e.g. history, archaeology etc.
文摘To reliably estimate water levels and velocities in vegetated rivers and floodplains, flow resistance models based on physical plant properties are advantageous. The purpose of this study is （1） to assess the suitable parameterization of woody riparian vegetation in estimating the drag forces, （2） to address the effect of plant scale on the drag estimates and reconfiguration, and （3） to evaluate the applicability of three recently developed flow resistance models. Experiments on four tree species in a towing tank together with detailed characterization of tree properties were carried out to establish a novel dataset. Despite the variability in the tree height （0.9 m-3.4 m）, the stem, leaf and total areas proved to be suitable characteristic dimensions for estimating the flow resistance at different scales. Evaluations with independent data revealed that the tested models produced reasonable results. The performance of the models was controlled by the parameter values used rather than the model structure or the plant scale.
基金International Foundation for Science,Stockholm,Sweden,through a grant to Mulubrhan Balehegn(D5056-1)Norwegian Research Council(Project 236373)National Natural Science Foundation of China(31361140360)
文摘Communal rangelands provide diverse ecosystem services to millions of pastoralists and agro-pastoralists. Resettling destitute communities into hitherto uninhabited communal rangelands and forests, a common practice throughout Sub-Saharan Africa, is a threat to the sustainable use of range and forest land resources. In order to understand the effect of resettlement on a semi-arid woodland in northwestern Ethiopia, satellite imagery of 23 resettlement villages taken over a period of fourteen years, and woody vegetation floristic data for three old resettlements, three new resettlements, two refugee camps and one protected area were analyzed using ANOVA and canonical correspondence analysis（CCA）. The normalized differential vegetation index（NDVI） and canopy cover around all village types decreased with disturbance gradients, while the magnitude of change varied according to the type of settlement. Limited canopy cover was observed in refugee camps and new resettlements, compared to old resettlements and protected areas. Woody vegetation height class showed a J shaped distribution in all sites except refugee camps（RC）, indicating a decline in vegetation. CCA showed that variables like site type, altitude and disturbance gradient significantly affected the diversity of woody species at the different sites. Comparison of individual species responses to disturbances indicated that low fodder value invaders like Dichrostachys cinerea, and many Acacia species were increasing in proportion and coverage at the expense of some multipurpose species including Tamarindus indica, Diospyros mespiliformis, and Pterocarpus lucens. In the absence of regulated vegetation use, resettlements result in a decline in overall vegetation cover and a shift in floristic diversity in favor of invasive species.
基金Annapurna Conservation Area Project (ACAP)Norwegian State Educational Loan Fund (Lnekassen)+2 种基金Faculty of Mathematics and Natural Sciences,University of Bergen for financingfunded by Norwegian Research Council(project no.148910/730)supported by The Norwegian Council for Higher Education Programme for Development Research and Education(NUFU Project ID:PRO 04/2002)
文摘Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only(Pisang site) while the other pair has clear differences in land use in addition to slope exposure(Braka site). In each site, we sampled 72 plots(36 on each slope) in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis(CA) results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site,mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables(e.g., radiation index) affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Braka. We conclude that slope orientation and land use are important factors in structuring the woody species composition and diversity in the arid Trans-Himalayan region. We suggest that both environmental and land use variables should be taken into consideration in future studies on plant community structure along the cultural landscapes.
基金sponsored by the National Natural Scientific Foundation of China (41501270 and 41530746)Foundation for Excellent Youth Scholars of Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences
文摘The colonization and development of biological soil crusts （BSCs） are rarely discussed when investigating vegetation restoration with difference arrangement and structure of anthropogenically damaged areas in semi-arid regions. The present study analyzes the relationships among coverage, height and density of woody vegetation and coverage and thickness of BSCs on the surface mine dumpsite in Heidaigou, China. Results showed that PR （Prunus sibirica L.）, PT （Pinus tabulaeformis Carr.） and PPr （P. tabulaeformis Carr., P. sibirica L.） types had the highest coverage of total BSCs, which were 76.8%, 75.9% and 78.9%, respectively and PR showed the thickest BSCs of 4.41 mm. There was a significant correlation between coverage and thickness of BSCs and coverage and height of woody vegetation as a unimodal curve. Our findings suggest that a single woody plant species and low level coverage and height （no more than 30% and 300 cm, respectively） of woody plants may be able to create suitable conditions for facilitating BSCs restoration on the surface of mine dumpsites. The effects of vegetation arrangement and structure on BSCs colonization and development should be considered in reconstructing and managing woody vegetation in disturbed environments, such as surface mine dumpsites in semi-arid areas.
基金funded by the Ethiopian Biodiversity Institute,Community Based Integrated Natural Resources Management(CBINRM)project grant
文摘To investigate the woody species composition,diversity and structure of Kuandisha Afromontane forest,vegetation and environmental data were collected from 53 plots of 10 m 9 50 m for trees and shrubs and 265 subplots of 2 m 9 4 m for seedlings were laid along eight transect lines. The local name, scientific name, abundance,DBH, height and percentage foliage cover of species were recorded. Environmental variables, namely altitude, latitude and longitude as well as disturbance levels were also recorded in each plot. Structure, basal area, importance value index（IVI） and species prioritization were analyzed using spreadsheet programs. Correlation coefficients, frequency, relative frequency, Shannon diversity index,Shannon evenness and vegetation classification were analyzed using an R package. Sixty-six species belonging to40 families were recorded. Fabaceae was the most diverse family consisting of seven species, followed by Euphorbiaceae and Asteraceae. In terms of habit, 29 species were trees, 28 were shrubs, and 9 were lianas. The overall Shannon diversity index was 2.5. The frequency and relative frequency of woody species with DBH C2.5 cm ranged from 1.9 to 92.5 and 0.1 to 5, respectively. Seedling density varied among species ranging from five to 9938 individuals ha-1. The total basal area of woody species having DBH C2.5 cm is 15.3 m2ha-1. The IVI of species ranged from 0.13 for Solanum giganteum Jacq. to 28.4 for Croton macrostachyus Del. The woody vegetation was classified into five community types. Species richness,diversity and evenness of communities were strongly positively correlated. On the other hand, the correlation between disturbance and seedling density, and species richness was strongly negative. Thus, among the recorded woody species, a significant portion was either lacking regeneration or selectively removed for various purposes.The lack of seedlings of those species is mainly attributed to anthropogenic disturbances particularly free grazing. As a result, 14 tree, seven shrub and one liana species were prioritized for conservation and management interventions.
文摘The present study assesses anthropogenic disturbances and their impacts on the vegetation in Western Himalaya,India on the basis of various disturbance parameters such as density,Total Basal Cover(TBC) of cut stumps,lopping percentage and grazing intensities.On the basis of canopy cover and frequency of disturbances(%),the studied forests were divided into highly disturbed(HD),moderately disturbed(MD) and least disturbed(LD) categories.The HD forests had the lowest canopy cover,lowest density and lowest TBC and the LD had the highest canopy cover,highest density and highest TBC.The MD forests occupied the intermediate position with respect to these parameters.Species richness was least in HD forests,highest in one of the MD forests while LD forest occupied an intermediate position.The percentage of regenerating species was lowest(54%) in HD and highest(72%) in MD.The density of seedlings and saplings was higher in one of the MD forests as compared to HD and LD.We concluded that the moderate disturbances do not affect the vegetation adversely;however the increased degree of disturbance causes loss in plant diversity;affects regeneration and changes community characteristics.Construction of hydroelectric projects at various places in the study area was found to be one of the most important sources of anthropogenic disturbances in addition to the routine anthropogenic disturbances like grazing,fuelwood collection and fodder extraction.If all proposed dams in the Indian Himalaya are constructed combined with weak national environmental impact assessment and implementation,it will result in a significant loss of species.Therefore,various agents of disturbances should be evaluated in cumulative manner and any developmental activities such as hydropower projects,which trigger various natural and anthropogenic disturbances,should be combined with proper cumulative environmental impact assessment and effective implementation to minimise the anticipated loss of vegetation.
基金funded by the National Remote Sensing Centre,Hyderabad,India under NRSC-DOS-DBTGovt.of India project entitled‘‘Biodiversity Characterization in Southern parts of Karnataka’’(Project Number:UAS(B)/DR/GOI/245/2011-12)
文摘Canopy gaps play a significant role in maintaining structure and composition of tropical forests. This study was carried out in tropical evergreen forests of central Western Ghats in India to understand the influence of canopy gap size and the relationship of gap regime attributes to diversity measures and regeneration. The average gap size in the study area was found to be 396 m2 and around half of gaps were 4–8 years old. Gaps created by natural single tree fall were smaller in size but significantly higher in number. Diversity and regeneration of woody species were compared with canopy gaps and intact vegetation. Species richness and diversity was higher in gaps than in intact vegetation. Macaranga peltata, a shade intolerant species dominated gaps while intact vegetation was dominated by shade tolerant Kingiodendron pinnatum.Gap size significantly influenced species diversity and regeneration. Gap area and age were significantly and negatively correlated with diversity measures but positively correlated with regeneration. Among all the attributes of gaps, regeneration was significantly positively correlated with light intensity. Gaps maintained species diversity and favored regeneration of woody species. In addition to gap size and age, other gap ecological attributes also affected species diversity and regeneration.
文摘Aims studies of species distribution patterns traditionally have been conducted at a single scale,often overlooking species-environment relationships operating at finer or coarser scales.Testing diversity-related hypotheses at multiple scales requires a robust sampling design that is nested across scales.our chief motivation in this study was to quantify the contributions of different predictors of herbaceous species richness at a range of local scales.Methods Here,we develop a hierarchically nested sampling design that is balanced across scales,in order to study the role of several envi-ronmental factors in determining herbaceous species distribution at various scales simultaneously.We focus on the impact of woody vegetation,a relatively unexplored factor,as well as that of soil and topography.light detection and ranging(liDAR)imaging enabled precise characterization of the 3D structure of the woody vegetation,while acoustic spectrophotometry allowed a particularly high-resolution mapping of soil CaCo3 and organic matter contents.Important Findings We found that woody vegetation was the dominant explanatory variable at all three scales(10,100 and 1000 m2),accounting for more than 60%of the total explained variance.in addition,we found that the species richness-environment relationship was scale dependent.many studies that explicitly address the issue of scale do so by comparing local and regional scales.our results show that efforts to conserve plant communities should take into account scale dependence when analyzing species richness-environment relationships,even at much finer resolutions than local vs.regional.in addition,conserving heterogeneity in woody vegetation structure at multiple scales is a key to conserving diverse herbaceous communities.
文摘Introduction:Forests form a major component of the carbon(C)reserves in the world’s ecosystems.However,little is known on how management influences C stocks of woody vegetation,particularly in dry areas.We developed regression models for two dominant tree species to predict C stocks and quantified the potential of community managed forests as C sinks.Methods:Plots were randomly selected from community-managed natural forest,herbivore exclosures,and from communal grazing land.Tree and shrub biomass were estimated using a regression model on the most dominant woody species while herbaceous biomass was determined using destructive sampling.Results:The simplest model,based on only one single predictor variable,showed a good fit to the data for both species(Juniperus procera and Acacia abyssinica).Diameter at breast height(r2>0.95)was a more reliable predictor than height(r2>0.54),crown diameter(r2>0.68)(p<0.001).The C content of the total biomass for the managed natural forest and the exclosure were estimated as,58.11 and 22.29 Mg ha−1,respectively,while that for the grazing land was 7.76 Mg ha−1,and the mean carbon content between the three land uses were significantly different(p<0.05).Conclusions:We conclude that forests managed by the community have a high potential for C sequestration and storage and their conservation should be promoted.
