基于ESDA-GWR的粮食单产及其驱动因子的空间异质性研究

在耕地面积扩展有限和城市化高速发展的背景下,粮食单产的区域差异对我国粮食安全具有重要意义。以我国31省（市、自治区）为研究单元,借助ESDA和GWR模型,结合我国各地自然条件的差异及其经济发展类型,揭示我国粮食单产的区域差异及其驱动因子的空间异质性。结果表明：1999—2008年,中西部地区粮食单产的增产对全国粮食产量的贡献越来越显著,75%的粮食单产增长潜力较大的区域集中在中西部;粮食单产存在着显著的空间相关性,各省域粮食生产重心发生移动,由传统的＂东部为主＂逐渐＂北上西进＂,向中西部地区欠发达省份集中;不同区域粮食单产的驱动因素呈现为一种非均衡联动的局域性特征,化肥施用量对粮食单产的影响在两个时间断面中差异最大,1999年回归系数全为正值,而在2006—2008年出现负值,这表明部分地区化肥对粮食单产的边际效应已经达到递减阶段。因此,应结合我国不同区域当前粮食单产的现状和驱动因子的效应机理,积极采取相应的有效措施以保障我国的粮食安全。

A Study on the Spatial Heterogeneity of Grain Yield Per Hectare and Driving Factors Based on ESDA-GWR

The regional difference of grain yield per hectare is very important for national food security in China,especially in the situation of limited arable land and rapid urbanization.Taking 31 provincical regiones as sampling unit in China,using the methods of ESDA and spatial analysis of GIS,and applying a spatially varying-coefficient based geographically weighted regression(GWR) model,the paper presents spatial heterogeneity of grain yield per hectare and driving factors according to difference in natural conditions and economic development types.The results showed that increase of grain yield per hectare in mid-west regions has a significant impact on grain productivity in China,because 75% of higher potential regions for yield increase are located in mid-west during 1999 to 2008.And there is a significant spatial correlation for grain yield per hectare in different regions,and there is a shift for the gravity center of grain yield per hectare from eastern to northern and western regions.Thd driving factors of different regions show a localization characteristic of no-stationary intercourse.The effect of additional application of fertilizer to grain per hectare exists larger difference because the coefficient estimations are all positive in 1999 and partially negative in 2006～2008,which indicated that some regions are in the phase of diminishing marginal returns for fertilizer.Therefore,effective measures should be adopted to ensure China’s grain security according to present situation of grain yield per hectare and effect mechanism of driving factors.