安徽省农田水分利用效率时空特征及其与气候因子的关系

生态系统水分利用效率(Water Use Efficiency,WUE)是衡量碳水循环耦合程度的重要指标,估算安徽省农田生态系统的WUE并分析其时空变异规律,探究其影响因素,对该区域农田水资源的科学配置和合理利用有着重要的意义。基于MODIS遥感数据和气象数据,分析安徽省近15年农田WUE的年际、年内时空变化特征以及与气候因子的关系,研究表明:(1) 2000—2014年间安徽省农田WUE的变化范围为1.38—1.66 g C mm~(-1)m~(-2),多年均值为1.54 g C mm~(-1)m~(-2),整体上农田WUE年际呈现增长变化趋势,变化率为0.011 g C mm~(-1)m~(-2);具有较强的空间分异性规律,整体上呈现北高南低趋势,淮河以北各市的农田WUE较高,高于全省多年均值,淮河以南地区的农田WUE则低于全省水平。(2)安徽省农田WUE的年内变化呈现双峰型变化格局,具有明显的季节性差异,表现为春季秋季夏季冬季;以淮河为界,南北各市变化趋势略有不同,淮河以南地区的最大值在4月份,淮河以北则以3月份为最高。(3)安徽省农田WUE动态变化受到气候因子降雨影响的区域占比17.14%;气温影响的区域占比0.73%;降雨和气温综合影响所占0.71%,而农田WUE与气温和降雨影响均不显著的区域占比为81.42%;因此,气候因素中降雨在安徽省农田WUE的变化中起主导作用,由于人为因素的干预,非气候因素对农田WUE变化的影响更大。

Spatio-temporal distribution characteristics of cropland water use efficiency and its relationship with climate in Anhui Province

Water use efficiency (WUE) of an ecosystem is an important index to measure the degree of coupling of the carbon and water cycles. The WUE of a cropland ecosystem in Anhui Province was estimated and the spatio-temporal distribution of cropland WUE was analyzed to explore its influencing factors, which will be of great significance for scientific allocation and rational utilization of water resources in the cropland region. This study focused on the application of data from moderate-resolution imaging spectroradiometer (MODIS) and meteorological data, estimated the cropland WUE, analyzed the spatio-temporal characteristics of cropland WUE in Anhui Province over the last 15 years, and evaluated the relationship of WUE with climatic factors. The results showed that 1) Between 2000 and 2014, the average annual cropland WUE for Anhui Province was 1.54 gC mm^-1 m^-2, ranging from 1.38 to 1.66 gC mm^-1 m^-2. As a whole, the annual growth trend of cropland WUE was 0.011 gC mm^-1 m^-2, and cropland WUE had a strong spatial variability in Anhui Province, where it was higher in the north and lower in the southern part of the province. The cropland WUE north of the Huaihe River was higher than that of the province as a whole, while that of the Huaihe River was lower than the province average. 2) The variation of cropland WUE in Anhui Province showed a bimodal change pattern with obvious seasonal variation, in the order of spring > autumn > summer > winter. Taking Huaihe as the boundary, the changing trends of the cities in the north and the south were slightly different. The maximum value south of Huaihe was in April, while that north of Huaihe was the highest in March. 3) The dynamic change of cropland WUE in Anhui Province was closely related to temperature and rainfall. The regions with cropland WUE changes resulting from non-climate factors made up 81.42% of the total area of cropland in the province, followed by that mainly affected by precipitation (17.14%) and temperature (0.73%), while the combination of precipitation and temperature had the smallest impact on water use efficiency (0.71%). Overall, rainfall played the most important role of all climatic factors in the changes in cropland WUE, but due to the influence of human factors, non-climate factors had a greater impact on cropland WUE changes.