The aims of this study were to assess how functional diversity (FD) and functional redundancy respond to subalpine meadow ecosystem degradation under anthropogenic disturbance and how species contribute to functional redundancy along the disturbance gradient. The study was carried out in the subalpine meadow in Mount Jade Dragon, which is located at the southeastern edge of the Tibetan Plateau. Four disturbance intensities [no disturbance (ND), weak disturbance (WD), moderate disturbance (MD) and severe disturbance (SD)] were identified. Species richness, soil properties and five key plant functional traits were assessed along the disturbance gradient. Simpson’s diversity index, FD based on the Rao algorithm, functional redundancy, community-weighted mean of each functional trait and species-level functional redundancy were determined. Unimodal change pattern of FD and functional redundancy along the disturbance gradient were found in the present study, with their maximum in MD and WD, respectively. Species diversity showed a decreasing trend with increasing disturbance intensity. As disturbance intensified, species with traits related to conservative growth strategies, such as low specific leaf area (SLA) and high leaf dry matter content (LDMC), decreased, whereas species with resource acquisitive strategies, such as small plant, high SLA and low LDMC, increased in the community. At the species level, species showed species-specific roles in functional redundancy. Notably, some species were important in the community in terms of their unique function. For instance, Ligularia dictyoneura in ND and Potentilla delavayi in MD and SD.
Transitional climate zones (TCZ) are characterized by instability due to rapid changes in climate and biological variables, and trees growing there are particularly sensitive to climate change. Therefore, knowledge about the shifted relationships of tree growth in response to climate warming will shape regional forest conservation and management strategies. China has experienced rapid warming in recent decades. However, how tree growth in semihumid to semiarid regions, such as the Guandi Mountains, responds to more sophisticated changes in the hydrothermal combination is not yet clear. In this study, we used tree-ring width data from three sites along an elevational gradient in the Guandi Mountains to present the response of Picea wilsonii Mast. radial growth to increasing temperature and elevational differences in the relationship between tree growth and climate. The results indicated that the Guandi Mountains have experienced rapid warming with a clear trend toward aridity. From 1959 to 1995, the radial growth of P. wilsonii was mainly influenced by temperature, while it was controlled by both temperature and precipitation after rapid warming in 1996. From 1959 to 2017, this species showed a generally consistent growth–climate relationship at different elevations in the Guandi Mountains. However, the radial growth of trees at higher elevations had a higher climatic correlation than at lower elevations, and it was more conditioned by higher summer temperatures and precipitation in December of the previous year. These results suggested that P. wilsonii was more susceptible to drought and high temperatures due to a warming climate and that more attention should be devoted to forest management, especially the adverse consequences of summer drought on P. wilsonii.
Freshwater fishes are threatened by increasing environmental changes and human disturbances. The Min River, the largest river in Southeastern China, contains unique fish fauna for the Oriental realm. Due to environmental changes brought by forty years of economic growth, fish numbers have dramatically declined. The average taxonomic distinctness in the 1970s was significantly higher than that in 2015, while no significant differences were found in the variation in taxonomic distinctness between the two periods. Due to the river network and habitat diversity, fish fauna composition showed significant spatial differences but lower variation than the decadal variation. Precipitation was determined to be the most influential factor in determining the spatial pattern of fish fauna, followed by temperature. Species introduced for aquaculture have invaded the endemic fish community after escape and should be reconsidered in the trade-offs between economic development and ecological protection.
This paper presented the fish species richness at geographical unit of the Yangtze River. According to the fish taxonomic catalogs and biological traits, R language method was used to determine taxonomic diversity and functional diversity and the components of each unit. Regression analysis was used to test the varying tendency of taxonomic and functional diversity corresponding to the change of species richness. •Functional diversity is compared against taxonomic diversity in capturing the structure of dynamic ecosystem.•The β-diversity indices of taxonomy and function were calculated and decomposed to evaluate the role of species turnover and nestedness in the formation process of fish spatial pattern.•An integrated diversity index, balancing α and β diversity of species richness, taxonomic and functional diversity, is used to screen the prior conservation zone.