DRIVING MECHANISM OF ENVIRONMENTAL VARIABLES FOR BIOMASS ACCUMULATION IN TIBETAN LARGE-SCALE GRASSLANDHong Sheng Liu, Chad Larson and Zewei Miao
As fragile high-altitude ecosystems, grasslands in the Tibetan Plateau are more vulnerable and sensitive to climate change than those in low-altitude areas. This study investigated the driving mechanism of environmental variables for above-ground and below-ground biomass stocks in large-scale Tibetan Plateau grasslands. We analyzed the influences of mean annual temperature, mean annual precipitation, soil bulk density and soil water content on biomass storage at 96 plots across the permafrost region of the Tibetan plateau. Results indicated that Below-ground biomass occupied about 84% of total biomass in Tibetan plateau grasslands. There were significant unimodal relationships between temperature and below-ground biomass and between temperature and total biomass, respectively. Both annual precipitation and soil moisture in the Tibetan Plateau played positively driving roles in biomass stocks in grassland ecosystems at both local and regional scales. The negative correlations between soil moisture and temperature and the unimodal relationships between annual precipitation and mean annual temperature implied that belowground and total biomass may be decreased in the Tibetan Plateau grasslands as global temperature increased in the future. The decrease of biomass stocks with an increase of global temperature may attribute to a decrease of soil moisture and precipitation rather than an increase of temperature caused by global warming.
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