Abstract:

vegetation precipitation-use efficiency is an important index to evaluate the response of vegetation to precipitation in arid and semi-arid areas. In this paper， we will use GIMMS ndvi3g NDVI data and meteorological data from 1982 to 2015 to retrieve PUE of desert steppe in Inner Mongolia， to study the temporal and spatial changes of PUE in different vegetation types and different regions， and to analyze the correlation between PUE and climate factors. The results showed that： （1） the average annual PUE of desert steppe was 0.51 gC·m^-2·mm^-1 from 1982 to 2015， and the distribution of PUE showed certain spatial heterogeneity. The area of desert steppe PUE increased significantly （P<0.01） and increased significantly （P<0.05） accounted for 35.88% and 55.41% of the total grassland area， and the area of desert steppe PUE decreased significantly （P<0.01） accounted for 8.70% of the total grassland area， and the PUE of desert steppe showed an increasing trend. （2） The average PUE of different vegetation types in desert steppe ranged from 0.34 to 0.56 gC·m^-2·mm^-1. Among all vegetation types， the PUE of Gramineae grassland was the largest， and that of Stipa caucasica was the smallest. In terms of significance， except for S. caucasica， the difference between vegetation types is not very significant. From the change of PUE， except for Gramineae grassland， PUE of other vegetation types showed an increasing trend. （3） There is a strong negative correlation between PUE and precipitation in desert steppe； the correlation between annual PUE and annual average temperature is not obvious； PUE is positively correlated with annual average solar radiation. The purpose of this study is to provide a theoretical basis for the sustainable utilization of vegetation water resources in arid desert steppe.

Key words: desert steppe, PUE, CASA model, correlation