黔东南地区土地利用格局的空间梯度变化特征

Spatial gradient change of land use patterns in Qiandongnan Prefecture

以1993、1999和2009年黔东南苗族侗族自治州的遥感影像为数据源,分析了黔东南州土地利用的空间结构在不同海拔梯度带以及不同时段的变化,研究了不同海拔梯度的景观空间格局变化以及土地利用的综合程度。结果表明:研究区低海拔区域的主要土地利用类型是耕地,高海拔区域的主要土地利用类型是林地;随着海拔的升高,土地利用的综合程度不断下降,1993—2009年,0～2 000 m范围内的土地利用综合程度不断提高。1993—2009年,0～1 200 m区域内斑块密度急剧减少,土地利用程度趋于单一化,团聚程度变弱,空间上更分散;1 200～2 000 m区域土地利用程度呈现多样化,破碎化程度增加,团聚程度增强,空间上更为集中。0～800m和1 600～2 000 m区域斑块形状总体上表现出规则—不规则—相对不规则的变化趋势,而800～1 600m和>2000m区域斑块的形状总体上趋于规则。

The paper is inclined to present our study of the spatial gradient change of land use patterns in Qiandongnan（Southeast of Guizhou） Prefecture based on DEM data and remote sensing maps of the place in 1993, 1999 and 2009. In this paper, we have analyzed the land use structure and the changing trend at the diverse elevation gradients during the study periods. First of all, we have classified the whole land use data into five types, that is, the forest, the farmland, the grassland, the water and the building sites. Then, we have defined the elevation gradients into six grades. And, next, we have extracted each gradient from the whole land use pattern. And, finally, we have worked out different indices for analyzing the land use features in proportion, area ratio matrixes, spatial variables of land use degree and their changes with the landscape pattern indexes. The results of our study indicate that all the land patterns exist at every gradient, while water resource only exists at the range of 0-1 600 m. While farmland remains the main land use type at the lower elevations, forest and grassland with some water areas and building areas are taking the place of the farmlands for the need of other uses. However, at higher elevations, forest remains the chief type of land use, with some amount of grassland, farmland, building areas turning into forests. And, furthermore, with the rising of sea-level, the spatial variation of land use degree declined, with more variations of land use augmented from 1993 to 2009 except for the areas of above 2 000 m for the natural forest protection program. From the standpoint of landscape, from 1993 to 2009, in the area of 0-1 200 m, the patch density has been declining drastically with spatial distributions more scattered. As to the elevation range of 1 200-2 000 m, the land use types have turned to be more complicated with more and more fragmentized and spatial distribution more aggregated. And, finally, in the range of 0-800 m and 1 600-2 000 m, a fluctuant change can be seen of the local landscape, though the range of 800-1 600 m and 〉2 000 m, looks more regular.