基于坡耕地与聚落空间耦合的三峡库区腹地奉节县人地关系研究

Man-land relationship of Fengjie county in the Three Gorges Reservoir Area based on coupling comparison of sloping cultivated lands and settlements

以三峡库区腹地奉节县的27个乡镇为例,应用网格分析技术,以1 km×1 km网格为单元,揭示了聚落与坡耕地资源之间的配置关系以及不同岩性区聚落—坡耕地耦合模式差异,并对研究区人地关系做了类型划分。结果表明:1奉节县27个乡镇聚落和坡耕地的空间分布表现出较强的空间趋同性,二者用地比、斑块等级大小高值都主要位于北部梅溪河河谷和中部长江河谷地区,低值主要分布于南部石灰岩地区;2坡耕地偏多型主要分布于砂岩区,坡耕地偏少型主要分布于石灰岩区,而坡耕地—聚落均衡型则表现出随机分布格局;3研究区坡耕地大量存在的原因主要归结于坡耕地基数大和坡耕地退耕难度大。受坡耕地分布的影响,坡耕地偏多型的土壤侵蚀较其他耦合类型严重;4 27个乡镇人地关系划分为人地矛盾突出型、人地矛盾较突出型、人地矛盾较缓和型和人地矛盾缓和型四种类型,而人地矛盾较突出类型所占比重最大,面临着退耕压力和耕地压力突出的双重问题。

Because of land bearing capacity difference in different rock- landform character areas in the hinterland of the Three Gorges Reservoir Area, the interactions, the response and feedback between people and environment are different accordingly. Furthermore, these differences are shown by the number and the spatial pattern of settlements, and the different processes and intensity of ecological degradation, such as soil erosion in different rocklandform areas. Therefore, the diversity and different adaptabilities are formed in different rocklandform areas of Three Gorges Reservoir Area from the view of human- environment interaction between sloping cultivated lands and the settlements, which is an important factor influencing the suitability of man-environment relationship. We choose the 27 towns, located in the central part of Fengjie County, as a study case. The study area is divided into 1712 research units（with the size of 1 km × 1 km） by applying grid unit analysis technology. We take the settlements as the ＂people＂, and the sloping cultivated lands and soil erosion as the ＂ground＂（environment）. Our object is to reveal the allocation relationships between settlements and sloping cultivated lands, the difference of coupled mode between settlements and sloping cultivated lands, and the human- environment interaction types of different rock- landforms in the study area. The results show that： a） The spatial distribution of settlements and sloping cultivated lands presents a strong spatial convergence, namely, the high proportion and the higher patch＇s grade of settlements and sloping cultivated lands are mainly distributed in the Meixi river valley in the north and the Yangtze River Valley in the middle, and their low value area is mainly distributed in exposed limestone area of the southern study area. b） Of all the coupling relationship types of sloping cultivated lands and settlements, the type of more sloping cultivated lands is mainly distributed in exposed sandstone region and the type of less sloping cultivated lands is mainly found in exposed limestone region, and the balanced type of settlements and sloping cultivated lands show a random distribution pattern. c） The reasons for the study area rich in the sloping cultivated lands are attributed to the large amount of sloping cultivated lands and the difficulty to convert from agricultural use. The soil erosion of the coupling type with more sloping cultivated lands is more serious compared with other types due to the fact that sloping cultivated lands are prone to soil erosion. d） The man-environment relationship of the 27 towns is identified in four types, i.e., the serious contradiction type, the medium contradiction type, the light contradiction type, and the coordinating type, among which, the area with medium contradiction between human and land accounts for the largest proportion, therefore, the study area is facing the dual problems of the cultivated land from grain to green and cultivated land pressure. The results verify the effectiveness of the theoretical assumptions proposed by this paper, and can provide the theoretical basis for the sloping cultivated lands utilization and the implementation to coordinate human- environment relationship in the hinterland of the Three Gorges Reservoir Area, which is a beneficial attempt and supplement for the study on the regional man-environment relationship.