土壤保持功能对土地利用变化的敏感性研究

土地利用/覆被变化作为人类活动的直观反映，深刻改变着地表植被覆盖和地表径流，进而导致土壤保持功能的变化。采用趋势分析法对重庆市2000—2015年土壤保持功能的变化趋势进行研究，采用交叉敏感系数法研究各地类转换对土壤保持功能的敏感性。结果表明：（1）研究区地类以林地和旱地为主，2000—2015年间林地、裸地、水体和建设用地的面积有所增加，旱地、草地和水田的面积有所减少。其中，建设用地增幅最大，达0.93%，主要来源于旱地和水田的转换；旱地降幅最大，达0.85%，主要流向建设用地和林地。（2）研究区2000—2015年间土壤保持量总体呈波动上升趋势。其中，基本不变的区域占比77.22%，增加和显著增加区域占比21.85%，减少和显著减少的区域占比0.10%。增加和显著增加的区域主要集中在500~1 000 m的旱地和林地，减少和显著减少的区域主要为海拔500 m以下的旱地。（3）旱地与草地、水田与林地之间的转换对土壤保持功能的变化敏感性最高（敏感性系数分别为11.01和6.73），其次是旱地与裸地、水田、水体之间，草地与水体、裸地、林地之间以及林地与水体、裸地之间的转换，其敏感性系数均大于1。

Sensitivity of Soil Conservation Function to Land Use Change

As a direct reflection of human activities, land use cover deeply influences the surface vegetation and surface runoff, which leads to the change of soil conservation. Taking Chongqing as a case study, the soil conservation change trend was studied by the trend analysis method and the sensitivity of soil conservation to land use transition was analyzed by the cross-sensitivity coefficient method. The results showed that: (1) The land types in Chongqing were mainly forest land and dry land. From 2000 to 2015, the area of forest land, bare land, construction land, and water increased, while the area of dry land, grassland, and paddy field decreased. The construction land had the largest increase, mainly from dry land and paddy fields. The dry land had the largest decline, mainly converted into construction land and forest land. (2) From 2000 to 2015, the amount of soil conservation in Chongqing increased, but the growth trend was not linear. The soil conservation with extremely significant and significant increase accounted for 21.85% of the total increase area, respectively, while those with extremely significant and significant decrease were 0.10%, and the rest was not changed basically. The increased and significantly increased areas were mainly concentrated in the dry land and forest land with an altitude of 500~1 000 m, while the decrease and significant decrease areas were mainly in the dry land below 500 m above sea level. (3) The transitions of dry land to grassland and paddy fields to forest land were the most sensitive land conversion types with sensitivity coefficients of 11.01 and 6.73. The transitions of dry land to bare land, paddy fields, and water, forest land to water and bare land, and grassland to water, bare land, and forest land was sensitive, and their sensitivity coefficients were higher than 1.