基于土地利用与植被恢复情景的土壤侵蚀演变特征

基于土地利用与植被恢复情景,使用USLE和土壤风蚀方程对坝上地区水蚀和风蚀强度进行估算。结果表明:(1)2015年坝上地区风蚀、水蚀和总侵蚀强度均值分别为8.83±5.15 t·ha^-1·a^-1、4.37±6.62 t·ha^-1·a^-1和13.22±8.18 t·ha^-1·a^-1;风蚀占总侵蚀67%,水蚀占33%。(2)土地利用调整情景下,风蚀、水蚀和总侵蚀强度分别减少4.9%～9.9%、2.9%～8.3%和4.3%～9.3%;土地利用+植被恢复情景下,风蚀、水蚀和总侵蚀强度则分别减少6.3%～13.8%、5.2%～16.2%和5.9%～14.3%。(3)土地调整面积与风蚀强度减少率呈对数关系,与水蚀强度减少率呈指数关系,与总侵蚀强度减少率呈线性关系(P<0.01)。本文结果可以为土壤侵蚀方程计算及区域土壤侵蚀防治提供数据参考。

Assessment of soil erosion change under land use and reforestation scenarios

Soil erosion can lead to deterioration of soil health because it degrades soil quality and disrupts both mechanical and chemical processes in the soil. In semiarid regions of northern China, soil erosion is dominated by water and wind erosion, and these two erosion types could occur contemporaneously. To understand appropriate mitigation strategies for soil erosion, we must determine the magnitude and relative influence of water and wind erosion, which varies greatly between regions. Both land use adjustment and reforestation are efficient measures to control soil loss. Many studies have explored the soil erosion reduction based on land use adjustment and reforestation. Bashang region, located in the typical semiarid, agropastoral ecotone of North China, was generally considered a region with severe wind and water erosion. In this study, under five scenarios of land use adjustment, assessment of water erosion and wind erosion in Bashang was conducted using USLE and wind erosion model. Our results show that, (1) regional wind erosion rates, water erosion rates and total erosion rates in Bashang are 8.83±5.15 t·ha^-1·a^-1, 4.37±6.62 t·ha^-1·a^-1 and 13.22±8.18 t·ha^-1·a^-1, respectively. Under five scenarios of land use adjustment, if reforestation practices are not included, (2) the reduction rates of wind erosion, water erosion and total erosion are 4.9%-9.9%, 2.9%-8.3% and 4.3%-9.3%, respectively. However, under the five scenarios, if reforestation practices are included, the reduction rates of wind erosion, water erosion and total erosion are 6.3%-13.8%, 5.2%-16.2% and 5.9%-14.3%, respectively. Thus, the soil erosion reduction rates just due to reforestation were 1.35%-3.93%, 2.27%-7.83% and 1.65%-5.00%, respectively for wind erosion, water erosion and total erosion. (3) We also found that, the reductions of wind erosion have logarithmic relation with the increase of forest land area, the reductions of water erosion have exponential relation with the increase of forest land area, correspondingly, and the reduction of total erosion have linear relation with the increase of forest land area (P<0.01). Our results indicate that, land use adjustment is an efficient measure for mitigating soil erosion, however, the reforestation practices after land use adjustment are important for reduction of soil loss, especially for reduction of water erosion in the study region.