Plant community structure responds strongly to anthropogenic disturbances, which greatly influence community stability. The changes in community structure, aboveground biomass（AGB）, biodiversity and community stabil...Plant community structure responds strongly to anthropogenic disturbances, which greatly influence community stability. The changes in community structure, aboveground biomass（AGB）, biodiversity and community stability associated with different management practices were studied with a three-year field investigation in a temperate steppe of Inner Mongolia, China. The species richness, Shannon-Wiener index, evenness, plant functional type abundance, AGB, temporal community stability, summed covariance, scaling coefficient and dominant species stability were compared among areas subjected to long-term reservation（R）, long-term grazing（G）, mowing since enclosure in 2008（M） and grazing enclosure since 2008（E）. Site R had higher perennial grass abundance and lower species richness than sites G, M and E, although the AGB was not significantly different among the four sites. The species structure varied from a single dominant species at site R to multiple dominant species at sites G, M and E. The long-term reservation grassland had lower biodiversity but higher stability, whereas the enclosed grassland with/without mowing had higher biodiversity but lower stability. Different stability mechanisms, such as the compensatory dynamics, mean-variance scaling and dominant species stability were examined. Results showed that community stability was most closely related to the relative stability of the dominant species, which supports the biomass ratio hypothesis proposed by Grime.展开更多
Individual phenological life-history variations in the context of seasonal conditions are well documented in fshes and birds.However,amphibians,a group heavily affected by habitat loss and fragmentation,have received ...Individual phenological life-history variations in the context of seasonal conditions are well documented in fshes and birds.However,amphibians,a group heavily affected by habitat loss and fragmentation,have received relatively little attention regarding research on life-history adaptations.Here we present 3 years of data on the timing of reproductive activity in a suburban European green toad(Bufotes viridis)population.We found annually consistent patterns of reproductive activity and investigated whether these were caused by allochrony or individual attributes.Body size(a proxy for age),body condition,and sex signifcantly affected the timing of reproductive activity.However,most individuals showed considerable overlap in their reproductive timeframe,refuting the existence of allochronic subpopulations.Our fndings may indicate life-history adaptations in the direction of a faster lifestyle in response to hazardous environments.We propose to focus further research efforts on phenological variations in the context of environmental conditions,and that phenological variations should be considered more strongly in amphibian conservation efforts.展开更多
基金funded by the National Natural Science Foundation of China (41030535, 41371069)the Fundamental Research Funds for the Central Universitiesthe Program for Changjiang Scholars and Innovative Research Team in University (IRT1108)
文摘Plant community structure responds strongly to anthropogenic disturbances, which greatly influence community stability. The changes in community structure, aboveground biomass（AGB）, biodiversity and community stability associated with different management practices were studied with a three-year field investigation in a temperate steppe of Inner Mongolia, China. The species richness, Shannon-Wiener index, evenness, plant functional type abundance, AGB, temporal community stability, summed covariance, scaling coefficient and dominant species stability were compared among areas subjected to long-term reservation（R）, long-term grazing（G）, mowing since enclosure in 2008（M） and grazing enclosure since 2008（E）. Site R had higher perennial grass abundance and lower species richness than sites G, M and E, although the AGB was not significantly different among the four sites. The species structure varied from a single dominant species at site R to multiple dominant species at sites G, M and E. The long-term reservation grassland had lower biodiversity but higher stability, whereas the enclosed grassland with/without mowing had higher biodiversity but lower stability. Different stability mechanisms, such as the compensatory dynamics, mean-variance scaling and dominant species stability were examined. Results showed that community stability was most closely related to the relative stability of the dominant species, which supports the biomass ratio hypothesis proposed by Grime.
文摘Individual phenological life-history variations in the context of seasonal conditions are well documented in fshes and birds.However,amphibians,a group heavily affected by habitat loss and fragmentation,have received relatively little attention regarding research on life-history adaptations.Here we present 3 years of data on the timing of reproductive activity in a suburban European green toad(Bufotes viridis)population.We found annually consistent patterns of reproductive activity and investigated whether these were caused by allochrony or individual attributes.Body size(a proxy for age),body condition,and sex signifcantly affected the timing of reproductive activity.However,most individuals showed considerable overlap in their reproductive timeframe,refuting the existence of allochronic subpopulations.Our fndings may indicate life-history adaptations in the direction of a faster lifestyle in response to hazardous environments.We propose to focus further research efforts on phenological variations in the context of environmental conditions,and that phenological variations should be considered more strongly in amphibian conservation efforts.
