内蒙古荒漠草原植被降水利用效率的时空特征

植被降水利用效率（PUE）是评价干旱、半干旱地区植被对降水响应的重要指标。利用1982—2015年GIMMS NDVI3g NDVI数据及同期气象数据反演内蒙古荒漠草原的PUE，研究荒漠草原不同植被类型、不同地区PUE时空变化，并分析了PUE 与气候因子的相关关系。结果表明：（1）1982—2015年间荒漠草原年均PUE为0.51 gC·m^-2·mm^-1，PUE的分布呈现出一定的空间异质性。荒漠草原PUE极显著增大和显著增大的面积分别占草原总面积的35.88%、55.41%，荒漠草原PUE极显著减小的面积占草原总面积的8.70%，荒漠草原PUE整体呈现增大趋势。（2）荒漠草原不同植被类型PUE均值范围0.34—0.56 gC·m^-2·mm^-1。各种植被类型中，东方针茅草原PUE最大，镰芒针茅草原PUE最小。除了镰芒针茅草原与其他植被类型差异显著以外，其他植被类型间差异不太显著。从PUE变化看，除了东方针茅草原PUE呈现下降趋势，其他植被类型PUE都呈现增大的趋势。（3）荒漠草原PUE与降水有很强的负相关性；草地年PUE与年均气温相关性不太明显；草地年PUE与年均太阳辐射呈正相关关系。

Spatial and temporal characteristics of precipitation utilization efficiency of desert steppe vegetation in Inner Mongolia

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.