基于空间平滑法的旱作区粮食产量时空变化与影响因素研究

在中国北方水资源约束愈发严峻的情境下,旱作区粮食产量格局及其驱动因素研究具有重要的现实意义。以1995—2015年县域粮食统计数据为基础,结合土地利用栅格数据等资料,应用空间平滑法,对东北及华北平原旱作区粮食产量的空间格局与演化过程进行了研究。在此基础上,分析了不同农业区影响粮食产量的自然及社会经济驱动因素。结果发现:1)近20a东北-华北平原旱作区粮食产量整体稳步提高,高产区范围逐渐扩大,具有明显的空间集聚特征,且华北平原旱作区粮食总产高于东北平原旱作区;2)粮食产量增速以中速增产为主,其次依次为慢速增产、高速增产、绝对减产,且东北平原旱作区粮食增产速率高于华北平原旱作区;3)东北平原旱作区粮食单产整体高于华北平原旱作区,且经过空间平滑处理后粮食单产栅格像元频率分布基本呈高斯分布,与客观规律相契合;而随着时间演替,直方图像元的峰值逐渐右移,且单产栅格呈逐渐分散的趋势,表明耕地生产力水平整体提升的同时差距也随之扩大;4)自然因素中的年均气温与燕山-太行山山麓平原农业区的粮食单产的相关性最高,年降水量及汇流能力与冀鲁豫低洼平原农业区的粮食单产的相关性最高,土壤类型与松嫩-三江平原农业区的粮食单产的相关性最高;5)粮食单产与社会经济因素的分析结果表明,粮食生产由劳动密集型逐渐向技术密集型方向转变,农业机械化的投入对研究区特别是东北平原旱作区的贡献尤为明显,化肥投入对研究区粮食增产始终发挥着巨大作用,而灌溉条件对于华北平原旱作区粮食生产的保障起到重要作用。研究结果可为粮食产量时空格局研究的方法创新方面有所裨益,并对不同农业区保持高产、稳产及耕地保育等方面提供参考。

Spatio-temporal changes and influencing factors of grain yield based on spatial smoothing method in dryland farming regions

As water constraints become increasingly severe in Northern China, it is of great significance to study the grain yield pattern and its driving factors in dryland farming regions. Based on the county-level grain statistics from 1995 to 2015, combined with land use raster data and other materials, we studied the spatial pattern and process of grain yield in dryland farming regions of the Northeast and North China Plain using spatial smoothing methods. In addition, the natural and socio-economic driving factors of grain yield in different agricultural regions were investigated. Our results showed that: (1) In the past 20 years, the grain yield increased steadily and high production area expanded gradually in the dryland farming regions of Northeast and North China Plain, with obvious spatial agglomeration characteristics. And the total grain yield in the plain of North China dryland farming regions was higher than that in dryland farming regions of the Northeast China Plain. (2) The main increase rate of grain yield exhibited a medium speed, followed by slow speed, high speed increase, and absolute reduction in production. And increase rate of the grain yield in the dryland farming regions of the Northeast China Plain was higher than that in the North China Plain. (3) The per unit area yield of grain in the dryland farming regions of Northeast China Plain was higher than that of the North China Plain. And after the spatial smoothing processing, the pixel frequency of per unit area yield of grain generally exhibited a Gaussian distribution, which is consistent with the objective laws. The peak value of histogram pixel gradually moved to the right, and the per unit yield grid showed a gradual decentralization trend over time, indicating that the regional yield gap increases with the overall improvement of cultivated land productivity. (4) The mean annual temperature among the natural factors had the highest correlation with the per unit area yield of grain of the agricultural regions in Yan-Taihang mountain foothill plain. The annual precipitation and confluence capacity exhibited the highest correlation with the per unit area yield of grain of the agricultural regions in Ji-Lu-Yu low-lying plain. The soil type showed the highest correlation with the per unit area yield of grain of the agricultural regions in Songnen-Sanjiang plain. (5) The correlation analysis of per unit area yield of grain with socio-economic factors showed that grain production was gradually shifting from labor-intensive to technology-intensive. And the application of agricultural machinery obviously contributed to the study area, especially to the Northeast dryland farming regions of China. The application of chemical fertilizers had always played a significant role in improving grain production in the study region. And irrigation conditions played a critical role in ensuring grain production in the dryland farming regions of North China Plain. In summary, the results of our study are helpful for the research of spatial-temporal pattern of grain yield, and can provide references for the maintenance of high yield, stable yield and cultivated land conservation in different agricultural areas.