黔西北喀斯特区域土地利用/覆盖变化对土壤侵蚀的影响

利用黔西北地区1974,1992和2008年共3期遥感影像解译的土地利用图,结合修正的通用土壤流失方程,分析和模拟了该区土地利用/覆盖变化前后的土壤侵蚀状况,以及主要地类转化类型的土壤侵蚀效应。结果表明,黔西北地区土地利用结构变化显著,1974—2008年灌木林和旱地面积变化剧烈,且呈现相反的变化趋势。1974—1992年,随旱地面积的显著增加,灌木林的显著减少,黔西北土壤侵蚀模数由29.55t/(hm2.a)上升到37.76t/(hm2.a),随旱地面积的显著减少,灌木林、有林地的显著增多,2008年下降到30.39t/(hm2.a);旱地和其他地类发生土壤侵蚀最为剧烈,大面积的灌木林转为旱地是1992年土壤侵蚀加剧的主要原因,而大面积的旱地转为灌木林和有林地使2008年土壤侵蚀状况显著改善,灌木林转为旱地仍是近期土壤侵蚀加剧的主要原因,应加强对灌木林的使用管理。

Effects of Land Use/Cover Change on Soil Erosion in Karst Area of Northwest Guizhou Province

Based on the land use maps of Northwest Guizhou Province,which were interpreted from Landsat images of 1974,1992and 2008,we analyzed and simulated the status of soil erosion before and after the land use/cover change(LUCC)and the soil erosion effect of main types of LUCC with incorporation of the revised universal soil loss equation(RUSLE).The results show that the structure of LUCC had changed significantly in Northwest Guizhou Province.The areas of shrub and cultivated land varied dramatically,showing opposite change trends from 1974to 2008.With great increment of cultivated land and decrement of shrub,the soil erosion modulus increased from 29.55t/(hm2.a)to 37.76t/(hm2.a)in the area from 1974to 1992.The area of cultivated land decreased and the area of shrub and forest increased from 1992to 2008,resulting a significant reduction in soil erosion〔30.39t/(hm2.a)in 2008〕.As cultivated land contributes most to soil erosion,the massive conversion from shrub to cultivated land was the main cause of severe soil erosion in 1992,while the extensive conversion from cultivated land to shrub and forest reduced soil erosion greatly in 2008.Even recently,the conversion from shrub to cultivated land caused a substantial amount of soil erosion.The related agencies should strengthen the management of shrub land.