陕西省植被水分利用效率及与气候因素的关系

水分利用效率是反映生态系统碳水循环的重要变量。利用MODIS的总初级生产力以及蒸散发数据产品，结合气象数据，对2002—2012年陕西省水分利用效率进行研究。结果发现，陕西省中部平原区年均WUE较高，北部年均WUE较低；在各植被类型中，耕地的年均WUE最高，达1.59 g/（m²·mm），而灌草地年均WUE则较低。在不同年降水量及年均温区域，WUE与气候因子的关系有所差别:在年降水量低于627 mm的地区，WUE随着降水量增加而增加；在年均温低于11℃的地区，WUE随着年均温的增加而增加。2002—2012年陕西省各植被类型WUE呈增加趋势，其中林地WUE增加趋势不显著。不同的植被类型，其WUE与气候因子关系也不同，其中降水量对WUE产生显著影响的地区主要集中在耕地和草地，而温度对WUE产生显著影响的地区主要集中在林地。

Vegetation Water Use Efficiency and Its Relationship with Climate in Shaanxi Province

Water use efficiency (WUE) is one of the most important variables linking the carbon with hydrological cycle. In this paper we used the MODIS data products including the MODIS-GPP (MOD17A3), MODIS-ET (MOD16A3) and the land cover (MOD12) to analyze the tempo-spatial characteristics of WUE in Shaanxi Province. Results showed that the annual average WUE was the highest in the middle plain, while the lowest in the northern plateau. WUE in crop land was the highest among various vegetation types (1.59 g/(m²·mm), while WUE in shrub and grassland was the lowest. The relationship between WUE and climate depended on the regions. The positive relationship between WUE and precipitation was found in the regions with precipitation less than 627 mm, the similar relationship of WUE with temperature was found in the regions with annual average temperature less than 11℃. During the period from 2002 to 2012, WUE showed an increasing trend, regardless of insignificant increasing for forest (p > 0.05). The regions with significant relationship between WUE and precipitation were mainly dominated by cropland and grassland, while the areas with insignificant relationship between WUE and temperature were dominated by forest.