The Accumulation Characteristics And Control Elements Of Carbon,Nitrogen And Phosphorus In Alpine Grassland On The Tibetan Plateau

The accumulate rate of element?EAR?is an essential process in natural terrestrial ecosystems.Accumulate process,are controlled by the external environment of vegetation,including the factors of climate,soil and the plant self.Thus,investigating the pattern,influence,and relationship of EAR and environment factors could improve our understanding of ecological process.Temporal variation in EAR not only reflects how communities respond to environment fluctuation,but also has important implications for predicting regional patterns in the future.Unfortunately,studies based on field measurement in the extreme environment of alpine grasslands to directly address this issue are rare.Here,we used data of EAR at community level of 115 sites across the Tibetan alpine grasslands in 2015 to investigate the spatial patterns and temporal variations of CAR?the accumulate rate of carbon?,NAR?the accumulate rate of nitrogen?and PAR?the accumulate rate of phosphorus?,the influence factors,and their relationships.Considering the interaction and coupling between the accumulate rate of elements,we also analysed the ratio characteristics of CAR/NAR,CAR/PAR and NAR/PAR.The main results and conclusions are as follows:1)The average of CAR,NAR and PAR are 0.50 g/day/m²?0.02 g/day/m² and0.20×10^-2 g/day/m² across the 115 sites,respectively.Through the changepoint ananlyse of EAR,we found that there are three patterns in CAR and two patterns in NAR and PAR on the Tibetan Plateau.Additionally,we also found that the accumulate rate of CAR,NAR and PAR are control by the variation of temperature and precipitation from the correlation and control analysis.The water and nutrient content in soil are significant increased by the accordant variation of temperature and precipitation,simultaneous,increased the availability of nutrient for plant.Therefore,the spatial patterns of EAR was consistent with the spatial patterns and comparable trends in the climate over the plateau.2)The CAR:NAR:PAR=250:10:1,and the average of CAR/NAR,CAR/PAR and NAR/PAR are 22.72,281.44 and 12.39,respectively.And the CAR and NAR was significantly increased by the PAR.This indicated that the PAR was the key factor that affects the CAR and NAR.The EAR in leaves mainly reflects the adaptation of plants to soil conditions for the EAR is closely associated with the element content in soil.Hence,the EAR in grassland ecosystem on the Tibetan Plateau may be limited by the conent of phosphorus in soil.