Human activity and urbanization result in urban-rural environmental gradients. Understanding effect of the gradients on soil properties is necessary for management of the soils around urban areas. In this study, soil ...Human activity and urbanization result in urban-rural environmental gradients. Understanding effect of the gradients on soil properties is necessary for management of the soils around urban areas. In this study, soil quality of some vegetable fields was characterized along an urban-rural gradient in Shaoxing County, Zhejiang Province. Fifteen soil physical and chemical properties were evaluated by using principal component analysis.Results showed that there was a great variation in the soil quality along the gradient. From rural to urban zones, soil organic matter, water-stable aggregates, cation exchangeable capacity (CEC), total N and P, and available K increased, whereas soil pH value decreased. In addition, Pb, Cu, Ni, Co, Zn and Cr in the soils tended to be accumulated toward the urban zone. Sequential chemical extraction showed that mobility of all the heavy metals in the soils tended to increase from the rural to the urban zones. The variation of soil properties accounted for by the first principal component was significantly explained by the difference in application rates of municipal wastes.展开更多
Aims Environmental gradients are drivers of species diversity;however,we know relatively little about the evolutionary processes underlying these relationships.A potentially powerful approach to studying diversity gra...Aims Environmental gradients are drivers of species diversity;however,we know relatively little about the evolutionary processes underlying these relationships.A potentially powerful approach to studying diversity gradients is to quantify the phylogenetic structure within and between assemblages arrayed along broad spatial and environmental gradients.Here,we evaluate the phylogenetic structure of plant assemblages along an environmental gradient with the expectation that the habitat specialization of entire lineages is an important evolutionary pattern influencing the structure of tree communities along environmental gradients.Methods We evaluated the effect of several environmental variables on the phylogenetic structure of plant assemblages in 145 plots distributed in northwestern South America that cover a broad environmental gradient.The phylogenetic alpha diversity was quantified for each plot and the phylogenetic beta diversity between each pair of plots was also quantified.Both the alpha and beta diversity measures were then related to spatial and environmental gradients in the study system.Important Findings We found that gradients in temperature and potential evapotranspiration have a strong relationship with the phylogenetic alpha diversity in our study system,with phylogenetic overdispersion in low temperatures and phylogenetic clustering at higher temperatures.Further,the phylogenetic beta diversity between two plots increases with an increasing difference in temperature,whereas annual precipitation was not a significant predictor of community phylogenetic turnover.We also found that the phylogenetic structure of the plots in our study system was related to the degree of seasonal flooding and seasonality in precipitation.In particular,more stressful environments such as dry forests and flooded forests showed phylogenetic clustering.Finally,in contrast with previous studies,we find that phylogenetic beta diversity was not strongly related to the spatial distance separating two forest plots,which may be展开更多
基金Project supported by the National Key Basic Research Support Foundation (NKBRSF) of China (No. 1999011809).
文摘Human activity and urbanization result in urban-rural environmental gradients. Understanding effect of the gradients on soil properties is necessary for management of the soils around urban areas. In this study, soil quality of some vegetable fields was characterized along an urban-rural gradient in Shaoxing County, Zhejiang Province. Fifteen soil physical and chemical properties were evaluated by using principal component analysis.Results showed that there was a great variation in the soil quality along the gradient. From rural to urban zones, soil organic matter, water-stable aggregates, cation exchangeable capacity (CEC), total N and P, and available K increased, whereas soil pH value decreased. In addition, Pb, Cu, Ni, Co, Zn and Cr in the soils tended to be accumulated toward the urban zone. Sequential chemical extraction showed that mobility of all the heavy metals in the soils tended to increase from the rural to the urban zones. The variation of soil properties accounted for by the first principal component was significantly explained by the difference in application rates of municipal wastes.
文摘Aims Environmental gradients are drivers of species diversity;however,we know relatively little about the evolutionary processes underlying these relationships.A potentially powerful approach to studying diversity gradients is to quantify the phylogenetic structure within and between assemblages arrayed along broad spatial and environmental gradients.Here,we evaluate the phylogenetic structure of plant assemblages along an environmental gradient with the expectation that the habitat specialization of entire lineages is an important evolutionary pattern influencing the structure of tree communities along environmental gradients.Methods We evaluated the effect of several environmental variables on the phylogenetic structure of plant assemblages in 145 plots distributed in northwestern South America that cover a broad environmental gradient.The phylogenetic alpha diversity was quantified for each plot and the phylogenetic beta diversity between each pair of plots was also quantified.Both the alpha and beta diversity measures were then related to spatial and environmental gradients in the study system.Important Findings We found that gradients in temperature and potential evapotranspiration have a strong relationship with the phylogenetic alpha diversity in our study system,with phylogenetic overdispersion in low temperatures and phylogenetic clustering at higher temperatures.Further,the phylogenetic beta diversity between two plots increases with an increasing difference in temperature,whereas annual precipitation was not a significant predictor of community phylogenetic turnover.We also found that the phylogenetic structure of the plots in our study system was related to the degree of seasonal flooding and seasonality in precipitation.In particular,more stressful environments such as dry forests and flooded forests showed phylogenetic clustering.Finally,in contrast with previous studies,we find that phylogenetic beta diversity was not strongly related to the spatial distance separating two forest plots,which may be
