The interpretation of patterns of biodiversity requires the disentanglement of geographical and environmental variables.Disjunct alpine communities are geographically isolated from one another but experience similar e...The interpretation of patterns of biodiversity requires the disentanglement of geographical and environmental variables.Disjunct alpine communities are geographically isolated from one another but experience similar environmental impacts.Isolated homogenous habitats may promote speciation but constrain functional trait variation.In this study,we examined the hypothesis that dispersal limitation promotes taxonomic divergence,whereas habitat similarity in alpine mountains leads to functional convergence.We performed standardized field investigation to sample non-volant small mammals from 18 prominent alpine sites in the Three Parallel Rivers area.We estimated indices quantifying taxonomic and functional alpha-and beta-diversity,as well as beta-diversity components.We then assessed the respective importance of geographical and environmental predictors in explaining taxonomic and functional compositions.No evidence was found to show that species were more functionally similar than expected in local assemblages.However,the taxonomic turnover components were higher than functional ones(0.471±0.230 vs.0.243±0.215),with nestedness components showing the opposite pattern(0.063±0.054 vs.0.269±0.225).This indicated that differences in taxonomic compositions between sites occurred from replacement of functionally similar species.Geographical barriers were the key factor influencing both taxonomic total dissimilarity and turnover components,whereas functional betadiversity was primarily explained by climatic factors such as minimum temperature of the coldest month.Our findings provide empirical evidence that taxonomic and functional diversity patterns can be independently driven by different ecological processes.Our results point to the importance of clarifying different components of beta-diversity to understand the underlying mechanisms of community assembly.These results also shed light on the assembly rules and ecological processes of terrestrial mammal communities in extreme environments.展开更多
Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch(Larix) forests, which are coniferou...Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch(Larix) forests, which are coniferous forests widely distributed in the mountainous and plateau areas in North and Southwest China, are critical for maintaining the environmental conditions and species diversity. Few studies of larch forests have examined the beta-diversity and its constituent components(species turnover and nestedness-resultant components). Here, we used 483 larch forest plots to determine the total betadiversity and its components in different life forms(i.e., tree, shrub, and herb) of larch forests in China and to evaluate the main drivers that underlie this beta-diversity. We found that total betadiversity of larch forests was mainly dependent on the species turnover component. In all life forms,total beta-diversity and the species turnover component increased with increasing geographic, elevational, current climatic, and paleoclimatic distances. In contrast, the nestedness-resultant component decreased across these same distances. Geographic and environmental factors explained 20%-25% of total beta-diversity, 18%-27% of species turnover component, and 4%-16% of nestedness-resultant component. Larch forest types significantly affected total beta-diversity and species turnover component. Taken together, our results indicate that life forms affect beta-diversity patterns of larch forests in China, and that beta-diversity is driven by both niche differentiation and dispersal limitation. Our findings help to greatly understand the mechanisms of community assemblies of larch forests in China.展开更多
To further study the fungal community in heavy metal contaminated ecosystems,soil samples were collected from an abandoned chromium(Cr)factory,and fungal community was analyzed by Illumina sequencing of Internal Trans...To further study the fungal community in heavy metal contaminated ecosystems,soil samples were collected from an abandoned chromium(Cr)factory,and fungal community was analyzed by Illumina sequencing of Internal Transcribed Spacer(ITS)amplicons.The results showed that Cr contamination changed the composition and structure of soil fungal community,but didn’t change the diversity.Fungus showed various responses to Cr contamination.LEfSe analysis revealed that the biomarker changed a lot in the Cr-contaminated samples in comparison with that in the control samples.The changes in fungal community may be caused by the direct toxic effects on fungi by high concentration of Cr and the significant change in soil properties resulting from Cr contamination.Among all the Cr fractions,organic matter-bound Cr and exchangeable Cr showed significant effects on the fungal community and organic matter also showed a significant effect on soil fungal community.展开更多
The spatial distribution pattern of organisms is a basic issue in understanding the mechanisms of community assembly. Although the spatial distributions of animals and plants have been well studied,those of microorgan...The spatial distribution pattern of organisms is a basic issue in understanding the mechanisms of community assembly. Although the spatial distributions of animals and plants have been well studied,those of microorganisms are still being debated. In this study, we used a fi sh gut microecosystem to detect the spatial pattern of microbes, because it can provide a relatively unifi ed and stable environment. Results suggest that the turnover of intestinal bacterial assemblages showed a weak but highly signifi cant negative correlation between similarity and distances in the microbial community, in respect of both grass carp intestinal loci distances and the geographical distance between fi sh sampling sites. Our results also suggest that intestinal bacterial assemblages responded to differences within the external environment and within different parts of the fi sh themselves. These results show that some, or possibly all, microbes are restricted in their distribution and that environmental factors are also important infl uences on the structure of intestinal bacterial assemblages. The fi sh gut microecosystem is useful in promoting study of the spatial distribution patterns of microorganisms.展开更多
Background： Ecosystem representation is one key component in assessing the biodiversity impacts of land-use changes that will irrevocably alter natural ecosystems. We show how detailed vegetation plot data can be use...Background： Ecosystem representation is one key component in assessing the biodiversity impacts of land-use changes that will irrevocably alter natural ecosystems. We show how detailed vegetation plot data can be used to assess the potential impact of inundation by a proposed hydroelectricity dam in the Mokihinui gorge, New Zealand, on representation of natural forests. Specifically we ask： 1） How well are the types of forest represented Locally, regionally, and nationally; and 2） How does the number of distinct communities （i.e. beta diversity） in the target catchment compare with other catchments nationally？ Methods： For local and regional comparisons plant species composition was recorded on 45 objectively located 400 m2 vegetation plots established in each of three gorges, with one being the proposed inundation area of the Mokihinui lower gorge. The fuzzy classification framework of noise clustering was used to assign these plots to a specific alliance and association of a pre-existing national-scale classification. NationaLly, we examined the relationship between the number of alliances and associations in a catchment and either catchment size or the number of plots per catchment by fitting Generalised Additive Models. Results： The four alliances and five associations that were observed in the Mokihinui lower gorge arepresent in the region but limited locally. One association was narrowly distributed nationally, but is the mostfrequent association in the Mokihinui lower gorge; inundation may have consequences of national importance to its long-term persistence. That the Mokihinui lower gorge area had nearly twice as many plots that could not be assigned to pre- existing alliances and associations than either the Mokihinui upper or the Karamea lower gorges and proportionally more than the national dataset emphasises the compositional distinctiveness of this gorge. These outlier plots in the Mokihinui lower gorge may be unsorted assemblages of species or reflect sampling bias or that native- dominated woody riparian vegetation is rare on the landscape. At a national scale, the Mokihinui catchment has a higher diversity of forest alliances and associations （i.e. beta-diversity） than predicted based on catchment size and sampling intensity. Conclusions： Our analytical approach demonstrates one transparent solution to a common conservation planning problem： assessing how well ecosystems that will be destroyed by a proposed land-use change are represented using a multi-scale spatial and compositional framework. We provide a useful tool for assessing potential consequences of land-use change that can help guide decision making.展开更多
Despite the exceptional species richness and endemism,the environmental drivers of plant diversity along old tropical mountains remain underexplored.The respective importance of vegetation types,elevation,slope,and so...Despite the exceptional species richness and endemism,the environmental drivers of plant diversity along old tropical mountains remain underexplored.The respective importance of vegetation types,elevation,slope,and soil to drive diversity across life-forms is poorly addressed.Here,we tested whether environmental variables drove local and regional plant diversity along an old tropical mountain according to the three main life-forms:graminoids,herbaceous and woody species.We sampled all Angiosperm species on 180 plots across five elevations,at the tropical old-mountain region of Serra do Cipó,South-eastern Brazil.We assessed soil,slope,and vegetation types,and calculated richness and beta-diversity,applying generalized least square models,linear mixed-models and partial Mantel tests to test for relationships.Richness of graminoids and herbaceous species increased with greater elevation and more nutrient-impoverished soils,while woody richness showed the inverse pattern.Beta-diversity was primarily driven by species turnover,correlated with elevation and soil and higher in less dominant vegetation types,with unique species.Despite the limited elevational range in these old mountains,it still played an important role in filtering woody species,while fostering graminoid and herbaceous species.Conservation and restoration actions need to foster the high regional diversity supported by the old mountain heterogeneous landscape and the diversity of life-forms,especially the dominant and highly diverse grassy component.展开更多
Background: Harvesting of forest products is a widespread driver of disturbance in developing nations, where policies are increasingly aimed at managing natural forests for sustainable use. There is thus need for rese...Background: Harvesting of forest products is a widespread driver of disturbance in developing nations, where policies are increasingly aimed at managing natural forests for sustainable use. There is thus need for research aimed at understanding the impact of resource use on forest habitats and concomitant effects on biodiversity.Afromontane forests in the Eastern Cape, South Africa are harvested informally for poles and medicinal bark and occur along elevational gradients of 800–1600 m above sea level. Patterns of spatial diversity and human disturbance are expected to be affected by elevation. Furthermore, species’ responses to disturbance are expected to vary depending on their level of habitat specialisation. Understanding harvest impacts on forest biodiversity thus requires disentangling the separate effects of elevation and disturbance, and considering forest-specialist and forest-generalist species separately. This study comprises two components. First, harvest activities, resultant harvestmediated habitat heterogeneity, and avifaunal species richness, composition and beta-diversity were compared across two elevational zones in a harvested forest. Second, the role of harvest-mediated habitat heterogeneity in driving patterns of avifaunal diversity were assessed, while controlling for elevation, and considering forest-specialist and forest-generalist species separately.Results: Harvest rates were higher, and activities more varied in the lower elevation zone, with significant impacts of harvesting on habitat features resulting in higher harvest-mediated habitat heterogeneity at lower elevations.Harvest-mediated increases in habitat heterogeneity positively affected forest-generalist species richness, while forest-specialist richness was negatively affected. While species composition of both groups differed across elevational zones, variation in harvest-mediated habitat heterogeneity did not fully account for this, suggesting that factors other than disturbance shape avifaunal communities along the elevation gradient. However, variation in harvest-mediated habitat heterogeneity accounted for the amount of beta-diversity attributed to species turnover in the forest-specialist assemblage, indicating that harvest disturbances affect the mechanisms driving beta-diversity of this group.Conclusion: Spatial patterns of avifaunal diversity are affected by elevation over a 300-m gradient. Harvesting results in increased habitat heterogeneity, which variably affects avifaunal communities at the forest-scale, with positive effects for forest generalists and negative effects for forest-specialists.展开更多
Biodiversity conservation has long been a subject of extreme interest to community ecologists,with a particular focus on exploring the underlying causes of species diversity based on niche and neutral theories.This st...Biodiversity conservation has long been a subject of extreme interest to community ecologists,with a particular focus on exploring the underlying causes of species diversity based on niche and neutral theories.This study aims to identify the potential determinants of species diversity in a deciduous broad-leaved forest in the transitional region from subtropical to temperate climate in China.We collected woody plant data and environmental variables in a fully mapped 25-ha permanent forest plot,partitioned the beta-diversity into local contributions(LCBD)and species contributions(SCBD),and then applied multivariate linear regression analysis to test the effects of biotic and abiotic factors on alpha-diversity,LCBD,and SCBD.We used variation partitioning in combination with environmental variables and spatial distance to determine the contribution of environment-related variations versus spatial variations.Our results showed that the indices of alpha-diversity(i.e.,species abundance and richness)were positively correlated with soil available phosphorus(P)and negatively with slope.For the betadiversity,environment and space together explained nearly half of the variations in community composition.Approximately 60%of the variation of LCBD in the understory layer,40%in the substory layer,and 29%in the canopy layer were jointly explained by topographic,soil and biological variables,with biotic factors playing a dominant role in determining the beta-diversity.Species abundance accounted for a large proportion of the variations in SCBD in each vertical stratum,and niche position(NP)was the ecological trait that significantly affected the variations in SCBD in the substory and canopy layers.Our findings help to gain better understanding on how species diversity in forest ecosystem responds to environmental conditions and how it is influenced by biotic factors and ecological traits of species.展开更多
Alpine wetlands are hotspots of carbon(C)storage and methane emission,and they could be key contributors to global warming.In recent years,rapid warming has lowered the water table in alpine wetlands on the Tibetan Pl...Alpine wetlands are hotspots of carbon(C)storage and methane emission,and they could be key contributors to global warming.In recent years,rapid warming has lowered the water table in alpine wetlands on the Tibetan Plateau,concurrent with intensified nitrogen(N)deposition via anthropogenic activities.We carried out a field experiment to investigate the ecological impacts of these two factors on soil bacterial and functional communities,which are essential drivers of greenhouse gas emissions.Nitrogen amendment alone decreased the phylogenetic alpha-diversity of bacterial communities which could be offset by lowered water table.In contrast,microbial functional alpha-diversity,revealed by a high-throughput microarray,remained unchanged.Both bacterial and functional beta-diversity responded to lowered water table,but only bacterial community responded to N amendment.The alpha-Proteobacteria,beta-Proteobacteria,and Bacteroidetes were the major responsive bacterial lineages,and C degradation,methanogenesis,alkaline shock,and phosphorus oxidation were the major responsive functional processes.Partitioning analysis revealed that N amendment changed bacterial community structure mainly via species loss processes but did not affect bacterial functional communities,with soil pH and ammonium as the key factors influencing changes in bacterial community structure.Conversely,lowered water table altered bacterial and functional communities through species substitution processes linked to soil pH and soil moisture.According to our results,the response mechanisms of microbial communities to lowered water table and N amendment are fundamentally different in alpine wetlands.展开更多
Aims The effects of traditional land use by mobile livestock keepers on biodiversity in forest steppe ecotones are insufficiently studied.Epiphytes are an important part of forest plant diversity.Here we analyze diffe...Aims The effects of traditional land use by mobile livestock keepers on biodiversity in forest steppe ecotones are insufficiently studied.Epiphytes are an important part of forest plant diversity.Here we analyze differences in the diversity and composition of the epiphytic lichen vegetation between the edge and the interior of Siberian larch forests in the Khangai Mountains,western Mongolia,which are highly subdivided into patches.We asked whether the epiphytic lichen vegetation at the forest edge differs significantly from that in the interior,whether the edge is inhabited by more nitrophilous species than the interior and whether the density of nomad camps around the forest affects epiphytic lichen diversity.Methods Cover percentages of epiphytic lichen species were recorded from 20 trees per plot on 6 plots in the interior and 6 plots at the edge of Larix sibirica forests.The position of nomad summer camps was surveyed using Global Positioning System.Data were analyzed with pairwise significance tests,analysis of similarities,nonmetric multidimensional scaling and canonical correspondence analysis.Important Findings The composition of the epiphytic lichen vegetation clearly differed between the two habitats,with more species being more frequent at the edge than in the interior.However,there was no difference in species richness(α-diversity).The epiphyte vegetation at the edge was more uniform and characterized by lower variation of tree-levelα-diversity and lowerβ-diversity than in the interior.At the edge,only nitrophytic lichens were dominant,whereas in the interior,nitrophytes and acidophytes were among the dominant species.This pattern is probably attributable to the spatial heterogeneity of the intensity of forest grazing and was shown to be influenced by the density of nomad summer camps in the vicinity of the forests.Tree-levelα-diversity increased with stem diameter,but high-diameter trees were rare.The results suggest that the present level of forest patchiness and the effect of forest grazing increases the diversity of epiphytic lichens on the landscape level,while logging of highdiameter trees reduces lichen diversity.展开更多
基金supported by the Second Tibetan Plateau Scientific Expedition and Research Program(STEP,2019QZKK0501)National Key Research and Development Program of China(2017YFC0505202)+2 种基金National Natural Science Foundation of China(31601874)National Natural Science Foundation of China(31702007)Biodiversity Survey,Monitoring,andAssessment Program(2019HB2096001006)。
文摘The interpretation of patterns of biodiversity requires the disentanglement of geographical and environmental variables.Disjunct alpine communities are geographically isolated from one another but experience similar environmental impacts.Isolated homogenous habitats may promote speciation but constrain functional trait variation.In this study,we examined the hypothesis that dispersal limitation promotes taxonomic divergence,whereas habitat similarity in alpine mountains leads to functional convergence.We performed standardized field investigation to sample non-volant small mammals from 18 prominent alpine sites in the Three Parallel Rivers area.We estimated indices quantifying taxonomic and functional alpha-and beta-diversity,as well as beta-diversity components.We then assessed the respective importance of geographical and environmental predictors in explaining taxonomic and functional compositions.No evidence was found to show that species were more functionally similar than expected in local assemblages.However,the taxonomic turnover components were higher than functional ones(0.471±0.230 vs.0.243±0.215),with nestedness components showing the opposite pattern(0.063±0.054 vs.0.269±0.225).This indicated that differences in taxonomic compositions between sites occurred from replacement of functionally similar species.Geographical barriers were the key factor influencing both taxonomic total dissimilarity and turnover components,whereas functional betadiversity was primarily explained by climatic factors such as minimum temperature of the coldest month.Our findings provide empirical evidence that taxonomic and functional diversity patterns can be independently driven by different ecological processes.Our results point to the importance of clarifying different components of beta-diversity to understand the underlying mechanisms of community assembly.These results also shed light on the assembly rules and ecological processes of terrestrial mammal communities in extreme environments.
基金supported by the Major Program for Basic Research Project of Yunnan Province (No. 202101BC070002)the National Natural Science Foundation of China (No. 32201426, No. 31988102)the National Science and Technology Basic Project of China (No. 2015FY210200)
文摘Beta-diversity reflects the spatial changes in community species composition which helps to understand how communities are assembled and biodiversity is formed and maintained. Larch(Larix) forests, which are coniferous forests widely distributed in the mountainous and plateau areas in North and Southwest China, are critical for maintaining the environmental conditions and species diversity. Few studies of larch forests have examined the beta-diversity and its constituent components(species turnover and nestedness-resultant components). Here, we used 483 larch forest plots to determine the total betadiversity and its components in different life forms(i.e., tree, shrub, and herb) of larch forests in China and to evaluate the main drivers that underlie this beta-diversity. We found that total betadiversity of larch forests was mainly dependent on the species turnover component. In all life forms,total beta-diversity and the species turnover component increased with increasing geographic, elevational, current climatic, and paleoclimatic distances. In contrast, the nestedness-resultant component decreased across these same distances. Geographic and environmental factors explained 20%-25% of total beta-diversity, 18%-27% of species turnover component, and 4%-16% of nestedness-resultant component. Larch forest types significantly affected total beta-diversity and species turnover component. Taken together, our results indicate that life forms affect beta-diversity patterns of larch forests in China, and that beta-diversity is driven by both niche differentiation and dispersal limitation. Our findings help to greatly understand the mechanisms of community assemblies of larch forests in China.
基金Project(51504298)supported by the National Natural Science Foundation of ChinaProject(2016JJ3146)supported by the Natural Science Foundation of Hunan Province,China+1 种基金Project(1053320171098)supported by the Fundamental Research Funds for the Central Universities of ChinaProject supported by the Postdoctoral Research Funding Plan in Central South University,China
文摘To further study the fungal community in heavy metal contaminated ecosystems,soil samples were collected from an abandoned chromium(Cr)factory,and fungal community was analyzed by Illumina sequencing of Internal Transcribed Spacer(ITS)amplicons.The results showed that Cr contamination changed the composition and structure of soil fungal community,but didn’t change the diversity.Fungus showed various responses to Cr contamination.LEfSe analysis revealed that the biomarker changed a lot in the Cr-contaminated samples in comparison with that in the control samples.The changes in fungal community may be caused by the direct toxic effects on fungi by high concentration of Cr and the significant change in soil properties resulting from Cr contamination.Among all the Cr fractions,organic matter-bound Cr and exchangeable Cr showed significant effects on the fungal community and organic matter also showed a significant effect on soil fungal community.
基金Supported by the National Basic Research Program of China(973 Program)(No.2009CB118705)the National Natural Science Foundation of China(Nos.30970358,31071896)the Youth Innovation Promotion Association,CAS
文摘The spatial distribution pattern of organisms is a basic issue in understanding the mechanisms of community assembly. Although the spatial distributions of animals and plants have been well studied,those of microorganisms are still being debated. In this study, we used a fi sh gut microecosystem to detect the spatial pattern of microbes, because it can provide a relatively unifi ed and stable environment. Results suggest that the turnover of intestinal bacterial assemblages showed a weak but highly signifi cant negative correlation between similarity and distances in the microbial community, in respect of both grass carp intestinal loci distances and the geographical distance between fi sh sampling sites. Our results also suggest that intestinal bacterial assemblages responded to differences within the external environment and within different parts of the fi sh themselves. These results show that some, or possibly all, microbes are restricted in their distribution and that environmental factors are also important infl uences on the structure of intestinal bacterial assemblages. The fi sh gut microecosystem is useful in promoting study of the spatial distribution patterns of microorganisms.
基金funded by Meridian Energy Limited,New Zealandby Core funding for Crown Research Institutes from the New Zealand Ministry of Business,Innovation and Employment’s Science and Innovation Group
文摘Background： Ecosystem representation is one key component in assessing the biodiversity impacts of land-use changes that will irrevocably alter natural ecosystems. We show how detailed vegetation plot data can be used to assess the potential impact of inundation by a proposed hydroelectricity dam in the Mokihinui gorge, New Zealand, on representation of natural forests. Specifically we ask： 1） How well are the types of forest represented Locally, regionally, and nationally; and 2） How does the number of distinct communities （i.e. beta diversity） in the target catchment compare with other catchments nationally？ Methods： For local and regional comparisons plant species composition was recorded on 45 objectively located 400 m2 vegetation plots established in each of three gorges, with one being the proposed inundation area of the Mokihinui lower gorge. The fuzzy classification framework of noise clustering was used to assign these plots to a specific alliance and association of a pre-existing national-scale classification. NationaLly, we examined the relationship between the number of alliances and associations in a catchment and either catchment size or the number of plots per catchment by fitting Generalised Additive Models. Results： The four alliances and five associations that were observed in the Mokihinui lower gorge arepresent in the region but limited locally. One association was narrowly distributed nationally, but is the mostfrequent association in the Mokihinui lower gorge; inundation may have consequences of national importance to its long-term persistence. That the Mokihinui lower gorge area had nearly twice as many plots that could not be assigned to pre- existing alliances and associations than either the Mokihinui upper or the Karamea lower gorges and proportionally more than the national dataset emphasises the compositional distinctiveness of this gorge. These outlier plots in the Mokihinui lower gorge may be unsorted assemblages of species or reflect sampling bias or that native- dominated woody riparian vegetation is rare on the landscape. At a national scale, the Mokihinui catchment has a higher diversity of forest alliances and associations （i.e. beta-diversity） than predicted based on catchment size and sampling intensity. Conclusions： Our analytical approach demonstrates one transparent solution to a common conservation planning problem： assessing how well ecosystems that will be destroyed by a proposed land-use change are represented using a multi-scale spatial and compositional framework. We provide a useful tool for assessing potential consequences of land-use change that can help guide decision making.
基金Sao Paulo Research Foundation(FAPESP)for financial support through the grants:#2009/54208-6Fapesp-Microsoft Research Institute#2013/50155-0+6 种基金Fapesp-Vale#2010/51307-0,#2021/10639-5 to LPCMthrough fellowships FAPESP#2015/10754-8 to MGGC and#2019/09248-1 to ASSCoordena??o de Aperfei?oamento de Pessoal de Nível Superior–(CAPES)for scholarships granted to MGGC(Process#88887.583309/2020-00)PPL(#88887.583146/2020-00)JSS(CAPES Finance Code 001)National Council for Scientific and Technological Development(CNPq)for the grants:CNPq-PVE#400717/2013-1 and PDJ#150404/2016-6 to SLSfor the productivity fellowship and grant#311820/2018-2,#306563/2022-3 to LPCM。
文摘Despite the exceptional species richness and endemism,the environmental drivers of plant diversity along old tropical mountains remain underexplored.The respective importance of vegetation types,elevation,slope,and soil to drive diversity across life-forms is poorly addressed.Here,we tested whether environmental variables drove local and regional plant diversity along an old tropical mountain according to the three main life-forms:graminoids,herbaceous and woody species.We sampled all Angiosperm species on 180 plots across five elevations,at the tropical old-mountain region of Serra do Cipó,South-eastern Brazil.We assessed soil,slope,and vegetation types,and calculated richness and beta-diversity,applying generalized least square models,linear mixed-models and partial Mantel tests to test for relationships.Richness of graminoids and herbaceous species increased with greater elevation and more nutrient-impoverished soils,while woody richness showed the inverse pattern.Beta-diversity was primarily driven by species turnover,correlated with elevation and soil and higher in less dominant vegetation types,with unique species.Despite the limited elevational range in these old mountains,it still played an important role in filtering woody species,while fostering graminoid and herbaceous species.Conservation and restoration actions need to foster the high regional diversity supported by the old mountain heterogeneous landscape and the diversity of life-forms,especially the dominant and highly diverse grassy component.
基金supported by the National Research Foundation(NRF)South Africa(FBIP 98871)
文摘Background: Harvesting of forest products is a widespread driver of disturbance in developing nations, where policies are increasingly aimed at managing natural forests for sustainable use. There is thus need for research aimed at understanding the impact of resource use on forest habitats and concomitant effects on biodiversity.Afromontane forests in the Eastern Cape, South Africa are harvested informally for poles and medicinal bark and occur along elevational gradients of 800–1600 m above sea level. Patterns of spatial diversity and human disturbance are expected to be affected by elevation. Furthermore, species’ responses to disturbance are expected to vary depending on their level of habitat specialisation. Understanding harvest impacts on forest biodiversity thus requires disentangling the separate effects of elevation and disturbance, and considering forest-specialist and forest-generalist species separately. This study comprises two components. First, harvest activities, resultant harvestmediated habitat heterogeneity, and avifaunal species richness, composition and beta-diversity were compared across two elevational zones in a harvested forest. Second, the role of harvest-mediated habitat heterogeneity in driving patterns of avifaunal diversity were assessed, while controlling for elevation, and considering forest-specialist and forest-generalist species separately.Results: Harvest rates were higher, and activities more varied in the lower elevation zone, with significant impacts of harvesting on habitat features resulting in higher harvest-mediated habitat heterogeneity at lower elevations.Harvest-mediated increases in habitat heterogeneity positively affected forest-generalist species richness, while forest-specialist richness was negatively affected. While species composition of both groups differed across elevational zones, variation in harvest-mediated habitat heterogeneity did not fully account for this, suggesting that factors other than disturbance shape avifaunal communities along the elevation gradient. However, variation in harvest-mediated habitat heterogeneity accounted for the amount of beta-diversity attributed to species turnover in the forest-specialist assemblage, indicating that harvest disturbances affect the mechanisms driving beta-diversity of this group.Conclusion: Spatial patterns of avifaunal diversity are affected by elevation over a 300-m gradient. Harvesting results in increased habitat heterogeneity, which variably affects avifaunal communities at the forest-scale, with positive effects for forest generalists and negative effects for forest-specialists.
基金supported by the National Natural Science Foundation of China(Nos.31971491,31770517)the Meituan Qingshan Special Commonweal Fund of China Environmental Protection Foundation(CEPFQS202169-20)。
文摘Biodiversity conservation has long been a subject of extreme interest to community ecologists,with a particular focus on exploring the underlying causes of species diversity based on niche and neutral theories.This study aims to identify the potential determinants of species diversity in a deciduous broad-leaved forest in the transitional region from subtropical to temperate climate in China.We collected woody plant data and environmental variables in a fully mapped 25-ha permanent forest plot,partitioned the beta-diversity into local contributions(LCBD)and species contributions(SCBD),and then applied multivariate linear regression analysis to test the effects of biotic and abiotic factors on alpha-diversity,LCBD,and SCBD.We used variation partitioning in combination with environmental variables and spatial distance to determine the contribution of environment-related variations versus spatial variations.Our results showed that the indices of alpha-diversity(i.e.,species abundance and richness)were positively correlated with soil available phosphorus(P)and negatively with slope.For the betadiversity,environment and space together explained nearly half of the variations in community composition.Approximately 60%of the variation of LCBD in the understory layer,40%in the substory layer,and 29%in the canopy layer were jointly explained by topographic,soil and biological variables,with biotic factors playing a dominant role in determining the beta-diversity.Species abundance accounted for a large proportion of the variations in SCBD in each vertical stratum,and niche position(NP)was the ecological trait that significantly affected the variations in SCBD in the substory and canopy layers.Our findings help to gain better understanding on how species diversity in forest ecosystem responds to environmental conditions and how it is influenced by biotic factors and ecological traits of species.
文摘Alpine wetlands are hotspots of carbon(C)storage and methane emission,and they could be key contributors to global warming.In recent years,rapid warming has lowered the water table in alpine wetlands on the Tibetan Plateau,concurrent with intensified nitrogen(N)deposition via anthropogenic activities.We carried out a field experiment to investigate the ecological impacts of these two factors on soil bacterial and functional communities,which are essential drivers of greenhouse gas emissions.Nitrogen amendment alone decreased the phylogenetic alpha-diversity of bacterial communities which could be offset by lowered water table.In contrast,microbial functional alpha-diversity,revealed by a high-throughput microarray,remained unchanged.Both bacterial and functional beta-diversity responded to lowered water table,but only bacterial community responded to N amendment.The alpha-Proteobacteria,beta-Proteobacteria,and Bacteroidetes were the major responsive bacterial lineages,and C degradation,methanogenesis,alkaline shock,and phosphorus oxidation were the major responsive functional processes.Partitioning analysis revealed that N amendment changed bacterial community structure mainly via species loss processes but did not affect bacterial functional communities,with soil pH and ammonium as the key factors influencing changes in bacterial community structure.Conversely,lowered water table altered bacterial and functional communities through species substitution processes linked to soil pH and soil moisture.According to our results,the response mechanisms of microbial communities to lowered water table and N amendment are fundamentally different in alpine wetlands.
基金Volkswagen Foundation to M.H,Ch.Dulamsuren and Ch.Leuschner for the project‘Forest regeneration and biodiversity at the forest steppe border of the Altai and Khangai Mountains under contrasting developments of livestock numbers in Kazakhstan and Mongolia’.
文摘Aims The effects of traditional land use by mobile livestock keepers on biodiversity in forest steppe ecotones are insufficiently studied.Epiphytes are an important part of forest plant diversity.Here we analyze differences in the diversity and composition of the epiphytic lichen vegetation between the edge and the interior of Siberian larch forests in the Khangai Mountains,western Mongolia,which are highly subdivided into patches.We asked whether the epiphytic lichen vegetation at the forest edge differs significantly from that in the interior,whether the edge is inhabited by more nitrophilous species than the interior and whether the density of nomad camps around the forest affects epiphytic lichen diversity.Methods Cover percentages of epiphytic lichen species were recorded from 20 trees per plot on 6 plots in the interior and 6 plots at the edge of Larix sibirica forests.The position of nomad summer camps was surveyed using Global Positioning System.Data were analyzed with pairwise significance tests,analysis of similarities,nonmetric multidimensional scaling and canonical correspondence analysis.Important Findings The composition of the epiphytic lichen vegetation clearly differed between the two habitats,with more species being more frequent at the edge than in the interior.However,there was no difference in species richness(α-diversity).The epiphyte vegetation at the edge was more uniform and characterized by lower variation of tree-levelα-diversity and lowerβ-diversity than in the interior.At the edge,only nitrophytic lichens were dominant,whereas in the interior,nitrophytes and acidophytes were among the dominant species.This pattern is probably attributable to the spatial heterogeneity of the intensity of forest grazing and was shown to be influenced by the density of nomad summer camps in the vicinity of the forests.Tree-levelα-diversity increased with stem diameter,but high-diameter trees were rare.The results suggest that the present level of forest patchiness and the effect of forest grazing increases the diversity of epiphytic lichens on the landscape level,while logging of highdiameter trees reduces lichen diversity.
