水分利用效率(WUE)是衡量植被耗水能力的重要指标。利用MODIS产品并结合土地利用类型和气象数据,对2001—2014年不同土地利用类型下的植被水分利用效率的时空变化特征及其对气候因子的响应进行了研究。结果 表明:(1)从空间上看,相较于其他土地利用类型,耕地年均WUE绝大部分区域在1.2 gC/(m2·mm)以上,而未利用地年均WUE基本处于0.6～1.2 gC/(m2·mm),集中分布在准噶尔盆地。(2)2001—2014年新疆地区各土地利用类型WUE整体上呈增加趋势,其中沼泽WUE增加比较显著。(3)新疆地区草地和未利用地月均WUE呈现出先增高后降低的“单峰型”分布格局,而沼泽和耕地年内WUE都呈现出“双峰型”分布格局。林地年内WUE在5—9月份变化较小。(4)从整体上看,各土地利用类型WUE与降水、平均风速和平均湿度呈显著负相关的区域要明显大于显著正相关的区域,而日照时数则相反。除未利用地之外,其他土地利用类型WUE与气温呈显著正相关性的区域要明显大于显著负相关性的区域。
Water use efficiency(WUE)is an important index to measure the water consumption capacity of vegetation. In this paper, the spatial-temporal change characteristics of vegetation WUE and its response to climate factors under different land use types in the period 2001—2014 were studied by using MODIS products and combining with land use types and meteorological data. The results show that:(1)in terms of space, compared with other land use types, the annual WUE of cultivated land was more than 1.2 gC/(m2·mm), while the annual WUE of unused land was basically between 0.6～1.2 gC/(m2·mm), which concentrated in Jungar Basin;(2)from 2001 to 2014, WUE of various land use types in Xinjiang showed an overall increasing trend, among which WUE of swamp increased significantly;(3)WUE of grassland and unused land in Xinjiang showed a ‘single peak' distribution pattern with increasing first and then decreasing, while WUE of swamp and cultivated land showed a ‘double peak' distribution pattern in the year, WUE of woodland changed little from May to September;(4)as a whole, the area with significant negative correlation between WUE and precipitation, average wind speed and average humidity was significantly larger than the area with significant positive correlation, while the sunshine hours are opposite to these relations; except the unused land, the area with significant positive correlation between WUE and air temperature was significantly larger than the area with significant negative correlation.
