科尔沁沙地近水区域土地利用及沙漠化时空过程研究——以奈曼旗为例

Land Use and Sandy Desertification around Surface Water in Horqin Sandy Land:A case study in Naiman Banner

以奈曼旗的西湖和舍力虎水库周边10km范围区域为研究地,以1987年至2007年期间5个年份的Land-satTM影像为基本数据源,按与水体的空间距离,对近水区域各类土地利用面积百分比进行分地带统计。该过程通过ArcGIS平台下的缓冲区分析完成。结果表明,近水区域的土地利用活动和沙地分布的空间差异性十分显著。结果显示:①近水区域土地利用空间分布受地表水资源分布影响显著,在1～6km范围以内,耕地面积百分比与到水体的距离呈正相关,草地、沙地面积百分比与到水体的距离呈负相关;②各类土地利用类型面积年际变化明显,草地面积百分比呈波动性降低,耕地面积百分比逐年上升,林地面积百分比在1999年后明显比1999年以前有所增加,沙地面积百分比在1999年以前呈现逐年升高的趋势,在1999年以后迅速降低;③土地利用活动的变异程度对近水区域沙地空间分布具有重要影响,二者具有明显的线性相关性。越靠近水体,土地利用活动的年际变化越频繁,导致过垦、过牧的可能性越高,沙地面积百分比越高。

The boundaries of Xihu Lake and Shelihu Reservoir in Naiman Banner were extracted with Landsat TM images derived in 1987. 1-km buffer-zones surrounding of the water area were constructed and the area percentage of each type of land use in each buffer zone was computed with the ArcGIS software. Land use data were extracted from Landsat TM images derived in 1987, 1992, 1999, 2002 and 2007. The results showed that： （1） The percentage of rangeland area was negatively related to the distance from the water area, especially within the distance of 6 km; The percentage of cultivated land area was positively related to the distance from the water area; The percentage of sandy land area was negatively related to the distance from the water area. （2） The percentage of rangeland area descended from 1987 to 2007, while the percentages of cultivated land area ascended. The percentages of forestry area increased slowly from 1987 to 1999 and increased rapidly after 1999. The sandy land decreased rapidly after 1999. （3） The variation coefficient of land use was positively related to the percentage of sandy land area. The significant change of land use near water area caused the high percentage of sandy land area.