Vegetation cover pattern is one of the factors controlling hydrological processes. Spatially distributed models are the primary tools previously applied to document the effect of vegetation cover patterns on runoff an...Vegetation cover pattern is one of the factors controlling hydrological processes. Spatially distributed models are the primary tools previously applied to document the effect of vegetation cover patterns on runoff and soil erosion. Models provide precise estimations of runoff and sediment yields for a given vegetation cover pattern. However, difficulties in parameterization and the problematic explanation of the causes of runoff and sedimentation rates variation weaken prediction capability of these models. Landscape pattern analysis employing pattern indices based on runoff and soil erosion mechanism provides new tools for finding a solution. In this study, the vegetation cover pattern was linked with runoff and soil erosion by two previously de- veloped pattern indices, which were modified in this study, the Directional Leakiness Index （DL[） and Flowlength. Although they use different formats, both indices involve connectivity of sources ,areas （interpatch bare areas）. The indices were revised by bringing in the functional heterogeneity of the plant cover types and the landscape position. Using both artificial and field verified vegetation cover maps, observed runoff and sediment production on experiment plots, we tested the indices＇ efficiency and compared the indices with their antecedents. The results illustrate that the modified indices are more effective in indicating runoff at the plot/hillslope scale than their antecedents. However, sediment export levels are not provided by the modified indices. This can be attributed to multi-factor interaction on the hydrological process, the feedback mechanism between the hydrological function of cover patterns and threshold phenomena in hydrological processes.展开更多
On the basis of the data of zooplankton biomass and three major taxa—— Copepoda, Chaetognatha andSiphonophora of May-June 1986, July-August and December 1987, the distributional patterns and the indicator species of...On the basis of the data of zooplankton biomass and three major taxa—— Copepoda, Chaetognatha andSiphonophora of May-June 1986, July-August and December 1987, the distributional patterns and the indicator species of zooplankton in the Kuroshio and adjacent waters of the East China Sea are preliminarily studied. The results are as follows:The horizontal distribution of zooplankton biomass and the abundance of copepods, chaetognaths and siphonophores arecurred in the continent area northwest of Taiwan and the south-centre section of the East China Sea continent, which are the mix front of different waters. Zooplankton in the water area inside of Ryukyu Islands presented low abundance and high diversity. There are clear seasonal variations in zooplankton biomass and abundance in the study area. The strength or weakness of different water masses and fronts is the basic reason for the variations of zooplankton biomass and abundance.The species composition of zooplankton in the study area is complex and varies, however, the tropic oceanic species predominates overwhelmingly. The distribution of different ecotype species evidences the distribution of different water masses and the state of mixture. The indicator species of each water mass are listed in the paper so as to provide grounds for the variation of currents in the Kuroshio area.The temperature and salinity of sea water are important factors affecting zooplankton distribution, composition and diversity , however the role of salinity is major. With the replacement of one season by another, the correlative levels of temperature and salinity to various zooplankton taxa are more or less significant.展开更多
Rapid urbanization has markedly affected urban ecosystem health(EH),making it imperative to explore the relationships between EH and urbanization,as well as to identify the key factors influencing EH.This study addres...Rapid urbanization has markedly affected urban ecosystem health(EH),making it imperative to explore the relationships between EH and urbanization,as well as to identify the key factors influencing EH.This study addresses 2 key research gaps:(a)The traditional pressure–state–response evaluation framework fails to integrate ecosystem service demands and landscape pattern indices and has not formed a comprehensive EH evaluation system.(b)There is a lack of research on investigating the drivers and thresholds of EH across the areas in different spatial relationship between urbanization and EH at the urban scale.Here,taking Wuhan,China,as an example,this study assesses EH utilizing an optimized pressure–state–response evaluation framework.Additionally,bivariate Moran’s I is used to analyze the spatial relationship between EH and urbanization.We use gradient boosting decision trees to flexibly model the nonlinear relationships between influencing factors and EH,while Shapley additive explanations quantify each factor’s contribution,enhancing model interpretability and clarifying their effects on EH.The findings reveal a spatial distribution pattern characterized by lower EH levels in central areas and higher EH levels in periphery areas,with a notable negative spatial correlation between EH and urbanization.The spatial heterogeneity and clustering of EH and urbanization across Wuhan exhibit a ringlike pattern radiating from the center to the periphery.Landscape pattern index and land use are identified as key influencing factors of EH in Wuhan,with substantial regional variation,necessitating targeted environmental protection strategies.This study offers insights into urban planning and policymaking,promoting sustainable urban development.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.40930528&41101096)the Chinese Academy of Sciences/State Administration for Foreign Experts Affairs International Partnership Program for Creative Research Teams of"Ecosystem Processes and Services"
文摘Vegetation cover pattern is one of the factors controlling hydrological processes. Spatially distributed models are the primary tools previously applied to document the effect of vegetation cover patterns on runoff and soil erosion. Models provide precise estimations of runoff and sediment yields for a given vegetation cover pattern. However, difficulties in parameterization and the problematic explanation of the causes of runoff and sedimentation rates variation weaken prediction capability of these models. Landscape pattern analysis employing pattern indices based on runoff and soil erosion mechanism provides new tools for finding a solution. In this study, the vegetation cover pattern was linked with runoff and soil erosion by two previously de- veloped pattern indices, which were modified in this study, the Directional Leakiness Index （DL[） and Flowlength. Although they use different formats, both indices involve connectivity of sources ,areas （interpatch bare areas）. The indices were revised by bringing in the functional heterogeneity of the plant cover types and the landscape position. Using both artificial and field verified vegetation cover maps, observed runoff and sediment production on experiment plots, we tested the indices＇ efficiency and compared the indices with their antecedents. The results illustrate that the modified indices are more effective in indicating runoff at the plot/hillslope scale than their antecedents. However, sediment export levels are not provided by the modified indices. This can be attributed to multi-factor interaction on the hydrological process, the feedback mechanism between the hydrological function of cover patterns and threshold phenomena in hydrological processes.
文摘On the basis of the data of zooplankton biomass and three major taxa—— Copepoda, Chaetognatha andSiphonophora of May-June 1986, July-August and December 1987, the distributional patterns and the indicator species of zooplankton in the Kuroshio and adjacent waters of the East China Sea are preliminarily studied. The results are as follows:The horizontal distribution of zooplankton biomass and the abundance of copepods, chaetognaths and siphonophores arecurred in the continent area northwest of Taiwan and the south-centre section of the East China Sea continent, which are the mix front of different waters. Zooplankton in the water area inside of Ryukyu Islands presented low abundance and high diversity. There are clear seasonal variations in zooplankton biomass and abundance in the study area. The strength or weakness of different water masses and fronts is the basic reason for the variations of zooplankton biomass and abundance.The species composition of zooplankton in the study area is complex and varies, however, the tropic oceanic species predominates overwhelmingly. The distribution of different ecotype species evidences the distribution of different water masses and the state of mixture. The indicator species of each water mass are listed in the paper so as to provide grounds for the variation of currents in the Kuroshio area.The temperature and salinity of sea water are important factors affecting zooplankton distribution, composition and diversity , however the role of salinity is major. With the replacement of one season by another, the correlative levels of temperature and salinity to various zooplankton taxa are more or less significant.
基金financially supported by the National Natural Science Foundation of China(Nos.72174158 and 72474164)the Fundamental Research Funds for the Central Universities of China(No.2042023kf0222)
文摘Rapid urbanization has markedly affected urban ecosystem health(EH),making it imperative to explore the relationships between EH and urbanization,as well as to identify the key factors influencing EH.This study addresses 2 key research gaps:(a)The traditional pressure–state–response evaluation framework fails to integrate ecosystem service demands and landscape pattern indices and has not formed a comprehensive EH evaluation system.(b)There is a lack of research on investigating the drivers and thresholds of EH across the areas in different spatial relationship between urbanization and EH at the urban scale.Here,taking Wuhan,China,as an example,this study assesses EH utilizing an optimized pressure–state–response evaluation framework.Additionally,bivariate Moran’s I is used to analyze the spatial relationship between EH and urbanization.We use gradient boosting decision trees to flexibly model the nonlinear relationships between influencing factors and EH,while Shapley additive explanations quantify each factor’s contribution,enhancing model interpretability and clarifying their effects on EH.The findings reveal a spatial distribution pattern characterized by lower EH levels in central areas and higher EH levels in periphery areas,with a notable negative spatial correlation between EH and urbanization.The spatial heterogeneity and clustering of EH and urbanization across Wuhan exhibit a ringlike pattern radiating from the center to the periphery.Landscape pattern index and land use are identified as key influencing factors of EH in Wuhan,with substantial regional variation,necessitating targeted environmental protection strategies.This study offers insights into urban planning and policymaking,promoting sustainable urban development.
