东北林草交错区土壤侵蚀敏感性评价及关键因子识别

土壤侵蚀是造成东北林草交错区生态脆弱的重要原因。论文应用GIS技术,综合降水、地形、土壤可蚀性、植被覆盖等因子,分析和评价了1990—2005年研究区土壤侵蚀敏感性时空变化过程,并通过叠加排序方法定量识别关键因子。结果表明:研究区以中度敏感为主,其次是轻度和高度敏感;中度敏感地区以大兴安岭山地为主,轻度敏感地区分布在东、西部平原地区,高度敏感地区主要分布在燕山山地和大兴安岭南部山地的林草交错区;从时间变化过程看,轻度、中度敏感地区面积增加,高度敏感地区面积减少,生态环境状况总体好转;地形起伏度和植被覆盖作为研究区土壤侵蚀关键因子,起主导作用。

Assessment of Soil Erosion Sensitivity and Key Factors Identification in the Wood-Grass Ecotone of Northeast China

Soil erosion is one of the important reasons causing ecological fragility in the wood-grass ecotone of Northeast China.Using GIS technology,and integrating influence of rainfall,terrain,soil erodibility,and vegetation cover,the paper analyzes sensitivity of spatial-temporal variation of soil erosion in the wood-grass ecotone of the study area during the period of 1990-2005.The results show that the soil erosion sensitivity in the wood-grass ecotone is dominated by medium-sensitivity and then light and high sensitivity.In 2005,the area of medium-sensitivity was 370021.36 km2,the areas of light-sensitivity and high-sensitivity were respectively 115544.38 km2 and 38934.25 km2,or being respectively 69.98%,21.83%,and 7.36%.The medium-sensitivity regions are mainly distributed in the Great Hing’an Mountains,light-sensitivity regions mainly occur in the eastern and western plains,meanwhile the highly-sensitivity regions are mainly distributed in the wood-grass ecotone between Yanshan Mountain and the southern part of the Great Hing’an Mountains.In terms of time sequence,the area of light-sensitivity regions and medium-sensitivity regions increased but that of highly-sensitivity regions had a drop of 54.10%,indicating this eco-environmental situation is getting improvement.By overlapping and ordering method,the paper identifies the key factors and their spatial distribution.The area of land fluctuating degree is the most significant factor in light-sensitivity region accounting for 78.32%,and the vegetation cover is the most significant factor in medium-sensitivity region being 81.17%.It’s worthy noting that the area of rain erosivity is the most significant factor in highly-sensitivity region being 81.07%.So the former two are the key factors affecting soil erosion sensitivity,while the latter,as a trigger affecting soil erosion sensitivity.