中国粮食主产区参考作物蒸散量演变特征与成因分析

在全球变暖的背景下，参考作物蒸散量（reference crop evapotranspiration，ET0）的改变及其空间分布势必对中国粮食主产区农业水资源规划、农业用水管理等产生重要影响。本文将中国粮食主产区划分为温带湿润半湿润地区（I区）、温带干旱半干旱地区（II区）、暖温带半湿润地区（III区）和亚热带湿润地区（IV区）4个子区域，基于粮食主产区265个站点1961-2013年53a气象数据，采用FAO-56 Penman-Monteith公式计算各站点逐日ET0，利用ArcGIS空间插值、Mann-Kendall趋势检验、敏感性分析和贡献率分析等方法，对该区域ET0的时空分布规律及其成因进行分析。结果表明：（1）近53a来，中国粮食主产区年均ET0为878.9mm，整体呈显著下降趋势，速率为0.47mm·a^-1（P＜0.05），I、II区和IV区年均ET0分别为741.8、1079.8和924.2mm且均有所减小，但变化趋势并不明显，III区年均ET0为940.2mm，呈极显著下降趋势，速率为1.21mm·a^-1（P＜0.01）。（2）全区及I-IV区ET0最敏感气象因子均为相对湿度，其敏感系数分别为-1.060、-1.232、-0.784、-1.114和-1.009。（3）全区及I-III区对ET0变化贡献最大的气象因子为风速，IV区为相对湿度。（4）风速的减小是造成粮食主产区全区及I-III区ET0减小的首要原因，风速减小和日照时数缩短是造成IV区ET0减小的主要原因。

Spatio-Temporal Variability and Cause Analysis of Reference Crop Evapotranspiration in the Main Grain Producing Areas of China

Under the background of global warming, the change and spatial distribution of reference crop evapotranspiration are bound to have an important impact on agricultural water resources planning and agricultural water management in the main grain producing areas of China. The main grain producing areas of China was divided into temperate humid and semi-humid area (I area), temperate arid and semi-arid area (II area), warm temperate semi-humid area (III area) and subtropical humid area (IV area) according to the difference of heat and humidity. Based on daily meteorological data of the 265 stations in the main grain producing areas of China during 1961 to 2013, the daily ET0 was calculated by Penman-Monteith equation recommended by Food and Agriculture Organization in 1998. The temporal and spatial variation of ET0 and its influencing factors were analyzed by using Arcgis spatial interpolation, Mann-Kendall trend test, sensitivity analysis and contribution rate analysis. The results showed that the annual ET0 in major grain producing areas of China was 878.9mm and had a significant downward trend as a whole at the rate of 0.47mm·y-1(P＜0.05) in the past 53 years. The annual ET0 of I, II and IV area decreased with the value of 741.8mm, 1079.8mm and 924.2mm respectively, but the trends of changes were not obvious. The annual ET0 of III area was 940.2mm, which had an extremely significant downward trend with a rate of 1.21mm·y-1(P＜0.01). Sensitivity analysis indicated that relative humidity was the most sensitive meteorological factor to annual ET0 change in the whole and I-IV area, with the sensitivity coefficient of -1.060, -1.232, -0.784, -1.114 and-1.009，respectively. Contribution analysis showed that wind speed made the greatest contribution to ET0 changed in I-III and whole area, while relative humidity was the meteorological factor that contributed most to the change of ET0 in IV area. The decrease of wind speed was the dominant cause of ET0 decrease in I-III and whole area, and the main reason for the decrease of ET0 in IV area were the decrease of wind speed and the shortening of sunshine hours.