Environmental heterogeneity significantly affects the structure of ecological communities.Exploring vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mec...Environmental heterogeneity significantly affects the structure of ecological communities.Exploring vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mechanism(s)driving vegetation succession,especially in the ecologically fragile areas.In this study,based on the quantitative analysis of plant community and environmental factors in 68 plots at 10 different transects in the Minqin oasis-desert ecotone(ODE)of northwestern China,we investigated desert vegetation distribution and species-environment relationships using multivariate analysis.Two-way indicator species analysis(TWINSPAN),detrended correspondence analysis(DCA),and canonical correspondence analysis(CCA)methods were used.A total of 28 species,belonging to 27 genera in 8 families,were identified.Chenopodiaceae,Zygophyllaceae,Gramineae,and Leguminosae were the largest families.Annual and perennial herbs accounted for 28.60%of the total number of plants,while shrubs(42.90%)were the most dominant.Nitraria tangutorum was the constructive species of the desert plant community.We divided the 68 plots surveyed in this study into 7 community types,according to the results of TWINSPAN.The distribution of these 7 communities in the DCA ordination graph showed that species with a similar ecotype were clustered together.Results of CCA indicated that groundwater was the dominant factor influencing vegetation distribution,while distance between plot and oasis(Dis)and soil electrical conductivity(EC)were the local second-order factors.Our study suggests that optimizing the utilization of groundwater in oases is key to controlling the degradation of desert vegetation.The favorable topographic conditions of sand dunes should be fully utilized for vegetal dune stabilization,and the influence of soil salinity on the selection of afforestation tree species should be considered.展开更多
The relationship between spatial patterns of macrobenthos community characteristics and environmental conditions(salinity, temperature, dissolved oxygen, organic matter content, sand, silt and clay) was investigated...The relationship between spatial patterns of macrobenthos community characteristics and environmental conditions(salinity, temperature, dissolved oxygen, organic matter content, sand, silt and clay) was investigated throughout the Gorgan Bay in June 2010. Principal components analysis(PCA) based on environmental data separated eastern and western stations. The maximum(4 500 ind./m2) and minimum(411 ind./m2) densities were observed at Stas 1 and 6, respectively. Polychaeta was the major group and Streblospio gynobranchiata was dominant species in the bay. According to Distance Based Linear Models results, macrofaunal total density was correlated with silt percentage and salinity and these two factors explaining 64% of the variability while macrofaunal community structure just correlated with salinity(22% total variation). In general, western part of the bay showed the highest number of species and biodiversity while, the highest density was found at Sta. 1 and in the middle part of the bay. Furthermore, relationship between diversity indices and macrobenthic species with measured factors is also discussed. Our results confirm the effect of salinity as an important factor on distribution of macrobenthic fauna in south Caspian brackish waters.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
基金supported by the National Key Research and Development Program of China(SQ2016YFHZ20617-03,2018YFC0507102-05)the National Natural Science Foundation of China(41661008,41761051,41761006,41661064,31560128,41801102)
文摘Environmental heterogeneity significantly affects the structure of ecological communities.Exploring vegetation distribution and its relationship with environmental factors is essential to understanding the abiotic mechanism(s)driving vegetation succession,especially in the ecologically fragile areas.In this study,based on the quantitative analysis of plant community and environmental factors in 68 plots at 10 different transects in the Minqin oasis-desert ecotone(ODE)of northwestern China,we investigated desert vegetation distribution and species-environment relationships using multivariate analysis.Two-way indicator species analysis(TWINSPAN),detrended correspondence analysis(DCA),and canonical correspondence analysis(CCA)methods were used.A total of 28 species,belonging to 27 genera in 8 families,were identified.Chenopodiaceae,Zygophyllaceae,Gramineae,and Leguminosae were the largest families.Annual and perennial herbs accounted for 28.60%of the total number of plants,while shrubs(42.90%)were the most dominant.Nitraria tangutorum was the constructive species of the desert plant community.We divided the 68 plots surveyed in this study into 7 community types,according to the results of TWINSPAN.The distribution of these 7 communities in the DCA ordination graph showed that species with a similar ecotype were clustered together.Results of CCA indicated that groundwater was the dominant factor influencing vegetation distribution,while distance between plot and oasis(Dis)and soil electrical conductivity(EC)were the local second-order factors.Our study suggests that optimizing the utilization of groundwater in oases is key to controlling the degradation of desert vegetation.The favorable topographic conditions of sand dunes should be fully utilized for vegetal dune stabilization,and the influence of soil salinity on the selection of afforestation tree species should be considered.
基金financially supported by the Iranian National Institute for Oceanography(INIO)
文摘The relationship between spatial patterns of macrobenthos community characteristics and environmental conditions(salinity, temperature, dissolved oxygen, organic matter content, sand, silt and clay) was investigated throughout the Gorgan Bay in June 2010. Principal components analysis(PCA) based on environmental data separated eastern and western stations. The maximum(4 500 ind./m2) and minimum(411 ind./m2) densities were observed at Stas 1 and 6, respectively. Polychaeta was the major group and Streblospio gynobranchiata was dominant species in the bay. According to Distance Based Linear Models results, macrofaunal total density was correlated with silt percentage and salinity and these two factors explaining 64% of the variability while macrofaunal community structure just correlated with salinity(22% total variation). In general, western part of the bay showed the highest number of species and biodiversity while, the highest density was found at Sta. 1 and in the middle part of the bay. Furthermore, relationship between diversity indices and macrobenthic species with measured factors is also discussed. Our results confirm the effect of salinity as an important factor on distribution of macrobenthic fauna in south Caspian brackish waters.
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.