基于遥感的吉林省中西部耕地数量和质量空间格局变化分析

耕地数量和质量变化直接关系到国家粮食安全和社会稳定,研究粮食主产区耕地数量和质量变化具有重要的现实意义。该研究利用2000年、2013年Landsat TM/ETM+/OLI遥感数据和2351个样点土壤实测数据,对吉林省中西部耕地分布的空间变化和由此引起的不同质量等级耕地的时空特征进行分析。结果表明:2000—2013年期间,吉林省中西部耕地总量稍有增加,面积由5.61×104 km2增加到5.64×104 km~2,其中旱田面积增加645 km2,水田面积减少350 km~2。研究区耕地分布表现出明显的西部增加、东部减少的趋势;新增耕地最主要来源于湿地(66.04%)和草地(21.12%),传统耕作区(主要为城市周边)耕地大面积减少,其中45.08%转化为人工表面,28.85%和22.61%转化为林地和湿地;水田与旱田之间的相互转化比较剧烈。2000—2013年期间,研究区耕地质量总体呈下降趋势,净减少的耕地为一、二等地,其中一等地净减少305 km~2,长春市占96%,净增加的耕地是三、四和五等地,分别为235、148和218 km~2,主要分布在白城市和松原市。城市化占用和耕地保护政策的实施是该区域耕地数量和质量变化的主要驱动因素,研究时段内吉林省中西部优质耕地流失严重,存在突出的占优补劣问题。

Spatial pattern analysis on quantity and quality of cultivated land in mid-west Jilin province based on remote sensing

Cultivated land resource is the material base that mankind depend on for existence.Understanding how the cultivated land changes in quantity and quality has an important significance for country''s food security and social stability.Based on the satellite images from Landsat TM/ETM in 2000 and OLI in 2013, this paper mapped the spatial distribution of cultivated land in the midwest Jilin province both in 2000 and 2013 and analyzed its temporal and spatial changes.Furthermore, soil data from 2351 field sampling points in study area were used to evaluate the quality of cultivated land and a comprehensive evaluation was made.Results revealed that cultivated land area in the midwest Jilin province increased from 5.61×104 km2 in 2000 to 5.64×104 km2 in 2013, among which dry farmland increased by 645 km2 and paddy field decreased by 350 km2.The transformation between dry land and paddy land was evident.Distribution of cultivated land changed differently from the east to the west:increasing in west part of study area and decreasing in east part, which resulted in the gravity center of cultivated land moved toward the west obviously.The increased cultivated lands were mainly converted from wetland and grassland, accounting for 66.04% and 21.12% of the total change area, respectively.The lost cultivated lands were mainly turned to artificial area, woodland and wetland with an area percent of 45.08%, 28.85% and 22.61%, respectively (mainly distributed around Changchun city).In terms of cultivated land quality, most cultivated lands were in uppermiddle grade in the midwest Jilin province in 2013, and the quality in the east part was better than that of the west.Although the total area of cultivated land increased, the quality of increased cultivated land mainly distributing in Baicheng and Songyuan city corresponded to lower grades including the third, fourth and fifth class with an area of 235,8 and 218 km2 respectively.Besides, the area of cultivated land in first class decreased by 305 km2, which mostly happened in the surrounding regions of Changchun city.The factors influencing the change of cultivated land were analyzed and we found that urbanization and policy were the most important driving forces to affect cultivated land quality and quantity.Accompanied by the rapid urbanization process, more and more highquality cultivated lands were occupied.Newly increased cultivated lands were mostly reclaimed from salinized land, alkalized land and wasteland, which led to an increase of cultivated land area and a decrease in quality.Overall, the cultivated land in the midwest Jilin province degraded severely during the past 15 years.This paper can provide an important reference for regional sustainable development of cultivated land resource.