Responses of aboveground biomass of alpine grasslands to climate changes on the Qinghai-Tibet Plateau

摘要

Aboveground biomass in grasslands of the Qinghai-Tibet Plateau has displayed an overall increasing trend during 2003-2016,which is profoundly influenced by climate change.However,the responses of different biomes show large discrepancies,in both size and magnitude.By applying partial least squares regression,we calculated the correlation between peak aboveground biomass and mean monthly temperature and monthly total precipitation in the preceding 12 months for three different grassland types (alpine steppe,alpine meadow,and temperate steppe) on the central and eastern Qinghai-Tibet Plateau.The results showed that mean temperature in most preceding months was positively correlated with peak aboveground biomass of alpine meadow and alpine steppe,while mean temperature in the preceding October and February to June was significantly negatively correlated with peak aboveground biomass of temperate steppe.Precipitation in all months had a promoting effect on biomass of alpine meadow,but its correlations with biomass of alpine steppe and temperate steppe were inconsistent.It is worth noting that,in a warmer,wetter climate,peak aboveground biomass of alpine meadow would increase more than that of alpine steppe,while that of temperate steppe would decrease significantly,providing support for the hypothesis of conservative growth strategies by vegetation in stressed ecosystems.