“关中—天水经济区”粮食作物水分生产力时空演变及其驱动力分析

Temporal and Spatial Evolution of Crop Water Productivity and Its Driving Forces in Guanzhong-Tianshui Economic Zone

基于2001~2020年粮食产量数据和土地覆盖、植被指数、地表温度、蒸散量等多种MODIS产品,通过对粮食产量空间化与MODIS数据重构,从而估算得到作物水分生产力,辅以趋势分析、Hurst指数分析、地理探测等方法,探讨了关—天经济区作物水分生产力时空变化特征、未来变化趋势以及其驱动力。结果如下:(1)2001~2020年关—天经济区粮食作物水分生产力呈现出明显的降低趋势,降低趋势为-0.59×10^(-2)kg/m^(3)/a,作物生长水分利用效率不断降低。(2)从粮食作物水分生产力未来变化特征可知,粮食作物水分生产力持续减小区面积比例达49.07%,主要分布于咸阳南部以东的中东部地区,集中于渭南大部分耕作区。关—天经济区中东部的粮食作物水分生产力将面临严峻考验,而经济区中西部区域粮食作物水分生产力将表现出较大的提升空间。(3)地表参数类因子对于粮食作物水分生产力分布的影响程度最高,其次为气象因子和地形因子,三类因子对粮食作物水分生产力分布的影响程度随时间变化均呈增加趋势,且地表参数影响程度增加趋势最为显著。因此,有效减少粮食作物蒸散量和地表温度,从而增加土壤贮水量是提高粮食作物水分生产力的直接途径,如施行秸秆还田、有机培肥、合理灌溉等措施。(4)从灌溉时间来看,第33~81天、第113~161天以及第193~209天q统计值均大于q均值,三个时段适当进行灌溉对提高粮食产量具有重要作用,其中在第65天(3月上旬)和第193天(7月中旬)土壤水分的变化对作物水分生产力的影响尤为显著。

Based on 2001~2020 grain yield data and land cover,vegetation index,surface temperature,evapotranspiration,and other MODIS products,crop water productivity is estimated through spatialization of grain yield and MODIS data reconstruction,supplemented by trend analysis.Hurst index,Geodetector,and other methods explore temporal and spatial variation characteristics,future trends,and driving forces of crop water productivity in the Guanzhong-Tianshui Economic Zone.The results are as follows:(1)The water productivity of grain crops in the Guanzhong-Tianshui Economic Zone show a significant downward trend from 2001 to 2020,with a decrease of-0.59×10^(-2)kg/m^(3)/a,and crop water use efficiency continuously decrease.(2)Regarding future changes in water productivity of food crops,the proportion continues to decrease by 49.07%,mainly in the central and eastern parts of South Xianyang and most farming areas in southern Anhui.The water productivity of grain crops in the central and eastern parts of the Guanzhong-Tianshui Economic Zone will face severe challenges,while that of food crops in the central and western regions shows significant potential for improvement.(3)Surface parameter factors have the highest impact on the distribution of food crop water productivity,followed by meteorological and topographic factors.The influence of these factors on food crop water productivity distribution increases over time,with surface parameters showing the most significant increasing trend.Therefore,effective reduction of food crop evapotranspiration and surface temperature,and increased soil water storage,such as through straw returning,organic fertilization,and reasonable irrigation,directly improves food crop water productivity.(4)From an irrigation timing perspective,statistical values for days 81,113~161,and 193~209 exceed the mean.Appropriate irrigation during these periods significantly enhances grain yield.Changes in soil moisture particularly affect crop water productivity on days 65(early March)and 193(mid-July).