基于遥感和GIS的平原和山区贫困县农村耕地利用演变对比

厘清耕地在不同地形环境下的利用情况与变化规律是实现农业现代化管理与脱贫攻坚的前提。结合遥感和GIS技术,该文对比了平原区贫困县(科尔沁左翼后旗)和山区贫困县(酉阳县)农村耕地数量、质量、分布与种植结构的演变差异。结果表明:1)平原县人均耕地数量远高于山区县,山区县耕地减少,但平原县耕地不降反增。2)平原县耕地质量较低,劣质耕地数量变化剧烈,山区县耕地质量略高,减少的耕地以中低质量为主。3)空间分布上耕地均呈集聚式发展,平原县耕作半径大于山区县,且向外扩张,山区县则向内收缩;平原县耕地斑块数和最大斑块指数持续增大,而山区县斑块数骤减且最大斑块略有增加;平原县平均斑块面积远大于山区县,研究期内均有不同程度地提高;平原县耕地面积加权平均斑块分维数提高,山区县则降低;平原县耕地优势分布在低地形位区,且变化不显著,山区县则优势分布在中低梯度区,且优势度增加。4)平原县普遍种植粮食作物,山区县以粮食作物为主,但经济作物占比较大且逐年增加。研究认为,地形与耕地资源禀赋的差异造成生产要素比较优势不同,进而耕地利用与农业生产模式不同,在社会经济和政策制度的驱使下,两县耕地利用朝着不同方向发展。

Comparison on evolution of rural farmland use in poverty-stricken counties between flat and mountainous areas based on remote sensing and GIS

Abstract: Recognizing the evolution and transformation progress of rural farmland under different terrain conditions is the basis of modernization management of agriculture, which will also help the targeted poverty alleviation in rural areas. Remote sensing and GIS (geographic information system) technology were used to analyze the farmland use in national-level poverty-stricken county of Horqin Left Wing Rear Banner in the flat area and Youyang County in the mountainous area. The analysis mainly focused on the variation of the quantity, quality, spatial distribution, configuration characteristic, distribution of topographic region and planting structure of farmland land from 2001 to 2015 when there is an enormous amount of migration from rural to urban areas. The results are as follows: 1) Compared with the mountainous county, the farmland per capita labor is more abundant in the plain county, but continuous expansion of farmland still occurs in the flat county while the shrink exists in the mountainous county. 2) The farmland quality of poverty-stricken county in the flat area is generally low and the inferior farmland changes obviously, by contrast, in the mountainous county, it is higher and the farmland of low and middle quality increases obviously. 3) The distribution of farmland in these 2 counties tended to cluster together; the farming radius in the flat county was expanding but it shrank in the mountainous county. The number of farmland patches and largest patch index increased in the flat county, while the number of farmland patches declined sharply and the largest patch index increased a little in the mountainous one. The mean patch size of farmland in the flat county was much larger than that in the mountainous county, but varying degrees were both increased. There was a raise of area-weighted patch fractal dimension of farmland in the flat county but a reduction in mountainous county. In the flat county, the low terrain niche range was the priority areas for development of farmland and there existed no significant change, while the middle-low terrain niche range was not the priority areas for development of farmland in the mountainous county. Meanwhile the advantage degree of farmland increased in the middle-low terrain niche range. 4) Generally, farmers in the flat counties prefer to plant food crops which are land-intensive agricultural products because of the man-earth relationship of wide land and few people, while commercial crops with greater weight are planted in mountainous county by contrast because of big population holding little tillable land. The results show that terrain and farmland resource are the critical factors influencing the difference of comparative advantage of regional production, which, to some extent, makes the pattern of farmland use and agricultural production various. Therefore, the investment and policy-making for agricultural modernization and targeted poverty alleviation must make the best use of the circumstances. The agricultural development mode in flat areas should change from extensive use of resources to protective utilization, so as to avoid the phenomenon of "land reclamation along with land desertification", which causes the soil desertification and the farmland quality decline. The development of agriculture in mountainous areas must change the traditional agricultural production mode to improve agriculture multifunction for the more value of "land economic output per unit area" through technological reformation and marketization.