Spatial Characteristics of Precipitation Use Efficiency on the Qinghai-Tibet Plateau From 1982 to 2007

Precipitation use efficiency(PUE),a ratio between the net primary productivity(NPP) and the annual precipitation,can be regarded as a key index to reflect the ecosystem water-carbon coupling.The data of PUE on Qinghai-Tibet Plateau during 1982—2007 were simulating by fully applying meteorological data,remote sensing data(NOAA AVHRR and SPOT VEGETAION) and vegetation information using the advanced CASA model.Then based on the 26-year data,the spatial distribution of vegetation's PUE,the distribution and variability of main vegetation types' PUE were calculated at full length.The results show that,the PUE on Qinghai-Tibet Plateau decreased from East to Midwest;the mean PUE of vegetation during the 26 years was 0.751 gC · m~(-2) ·mm~(-1).Furthermore,the PUE values of various vegetation types in Qinghai-Tibet Plateau ranked from large to small as follows:broad-leaved forest,cultivated plants,mixed broadleaf-conifer forest,swamp,meadow,coniferous forest,shrub,tussock,grasslands,desert,and mountain vegetation.PUE on Qinghai-Tibet Plateau is affected by both altitude and vegetation type.When the altitude is the same,PUE is were influenced by type of vegetation,and when the vegetation type is the same,PUE would decrease while altitude increases.