气候变化对甘肃省雨养农业区玉米种植区划的影响

Impact of climate change on maize-planting zoning in rainfed agricultural area of Gansu Province

以甘肃省雨养农业区55个气象站1971—2015年气温和降水实测资料为基础,根据玉米生长发育对气象条件的需求,运用综合评判法筛选出7月平均气温、≥10℃积温和年降水量作为玉米种植适宜性气候区划指标。采用线性倾向率法、累积距平、ArcGIS空间分析技术及Mann-Kendall法对研究区气候指标的时空变化特征及其突变进行了分析,结合玉米种植地理分布信息,建立适宜度评价模型,对气候变化背景下玉米种植适宜区的空间分布变化进行分析。结果表明:(1)近45 a来,甘肃省雨养农业区7月平均气温和≥10℃积温均呈明显的上升趋势,以0.29、98.13℃·10 a^(-1)的速率显著增暖,并分别于1994年、2000年发生突变;年降水量总体呈减少趋势,存在强烈波动变化,以-2.57 mm·10 a^(-1)的速率缓慢下降,1988年发生突变。(2)从空间分布来看,7月平均气温和≥10℃积温总体呈现出由北向南、由西向东递增的格局;降水量空间变化不规律,研究区中部降水少,四周降水较多。(3)气候变化导致研究区玉米可种植区域向高海拔地区移动,海拔上移了500 m,玉米种植的界限发生了较明显的空间位移,北移、西扩显著,从陇中、陇东、陇南地区扩展至甘南地区,适宜于种植的耕地总面积达2.27×10^(6) hm^(2),比2000年前增加了5.85×10^(4) hm^(2),在总耕地面积的基础上增加了2.4%,其中最适宜区增加最为显著,达15.9%。玉米种植适宜程度区划的区域分配有差异,2000年后甘肃省雨养农业区玉米种植最适宜区耕地面积较之前增加3.84×10^(5) hm^(2),次适宜区、适宜区和不适宜区耕地面积分别缩小2.54×10^(5) hm^(2)、7.1×10^(4) hm^(2)和5.9×10^(4) hm^(2)。

This paper used the measured data of temperature and precipitation from 55 meteorological stations in rainfed agricultural areas in Gansu province from 1971 to 2015,according to the requirements of the growth and development of maize crops on meteorological conditions,the average temperature in July,accumulated temperature of≥10℃,and annual precipitation were selected as indicators for the climatic zoning of maize planting suitability by using the comprehensive evaluation method.Linear tendency rate method,cumulative anomaly,Arc GIS spatial analysis technology,and Mann-Kendall method were used to analyze the temporal and spatial change characteristics and mutations of climate indicators in the study area,combined with the geographical distribution information of maize planting,we established a suitability evaluation model and analyzed the difference the spatial distribution of suitable areas for maize planting under the background of climate change.The results showed:(1)In recent 45 years,the average temperature in July and accumulated temperature≥10℃of the rainfed agricultural area in Gansu province had shown a significant upward trend,with the rate of 0.29℃·10 a^(-1)and 98.13℃·10 a^(-1),respectively,with abrupt changes in 1994 and 2000.The annual precipitation generally showed a decreasing trend,with strong fluctuations,and declined slowly at a rate of-2.57 mm·10 a^(-1)and changed abruptly in 1988.(2)From the perspective of spatial distribution,the average temperature in July and accumulated temperature of≥10℃generally showed a increasing pattern from the north to the south and the west to the east.The spatial trend of the precipitation varied irregularly and spatial pattern showed less precipitation in the central region of the study area and more precipitation in the surrounding areas.(3)Climate change had caused the maize plantable area in the study region to move to the high-altitude areas,the altitude had moved up by 500 m,the boundary of maize planting had shifted significantly in space,the northward and westward expansion were significant,from Longzhong,Longdong,and Longnan regions to Gannan region.The suitable total area of arable land for planting reached to 2.27×10^(6) hm^(2),an increase of 58500 hm^(2)over 2000,increased by 2.4%based on the total arable land area,the most suitable area increased significantly up to 15.9%.There were differences in the regional distribution of the suitable degree of maize planting.After 2000,the cultivated land area of the most suitable area for maize planting in the rainfed agricultural area of Gansu Province increased by 3.84×10^(5) hm^(2),and the cultivated land area of the sub-suitable area,suitable area,and unsuitable area decreased by 2.54×10^(5),7.1×104,and 5.9×10^(4) hm^(2),respectively.