气候和土地利用变化影响下生态屏障带水土流失趋势研究

Abstract

受气候和地形等诸多因素影响，我国"两屏三带"国家生态屏障带中的川滇-黄土高原区域和南方丘陵带水土流失十分严重，自然灾害频发。但是，针对川滇-黄土高原区域和南方丘陵带水土流失时空格局变化，特别是未来气候变化和土地利用变化影响下水土流失变化趋势的研究很少。因此，本研究以川滇-黄土高原区域和南方丘陵带为研究对象，利用修正土壤流失方程（RUSLE）定量分析了该区在2000-2015年水土流失的时空变化规律及其影响因素，并预测了在RCP2.6和RCP4.5的未来气候情景下及土地利用变化条件下水土流失的变化趋势。研究结果表明：（1）黄土高原地区在植被恢复的积极作用下，水土流失显著缓解；（2）川滇地区的西南部因植被盖度的增长和降雨的减少水土流失显著缓解，但四川省境内人口密集区农田面积增加以及降水增加造成水土流失大幅度加剧；（3）南方丘陵带受降水增加影响导致了部分区域的水土流失恶化；（4）在未来气候变化情景下，由于大部分地区降雨将减少使土壤侵蚀趋于缓解，但四川、黄土高原和南方丘陵带大部分地区仍然面临未来农田面积增加带来的水土侵蚀压力。考虑到未来气候变化情景下降雨减少的趋势，建议在黄土高原地区提高草地在土地利用类型中的占比，在减少耗水量的同时维持地表盖度，缓解水土侵蚀；此外，各区域仍需控制农田面积，而且需通过加强坡耕地上保水保土耕作措施降低农田区域的土壤侵蚀压力。;Under the influence of climate, tectonics, and topography, soil erosion is most severe in the Loess Plateau and the Southern Hilly Mountain of China, which causes ecological degradation, frequent natural disasters, and other potential dangers. At present, there are few research on the spatio-temporal changes of soil erosion on the Loess Plateau and the Southern Hilly Mountain of China and its underlying mechanism, in particular, tendency projections on soil erosion under climate change and land use scenarios. Therefore, in this study, the Sichuan-Yunnan-Loess Plateau region and the Southern Hilly Mountain belt were selected as the target area to explore the soil erosion change in 2000-2015 using Revised Universal Soil Loss Equation (RUSLE). At the same time, we also predicted the future trend of soil erosion under the combined impacts of climate change (scenarios RCP2.6 and RCP4.5) and land use change. The results show that:(1) soil erosion has been significantly alleviated under the positive effects of vegetation restoration in the Loess Plateau. (2) Soil erosion in the southwestern Sichuan-Yunnan-Loess Plateau region has been significantly alleviated due to the increase in vegetation coverage accompanied by the decrease in rainfall. However, in Sichuan Province, the increased soil erosion occurred due to the increasing farmland in the densely populated areas along with the greatly increased precipitation. (3) The deterioration of soil erosion in some areas took place due to the increasing precipitation in the Southern Hilly Zone. (4) Under future climate change scenarios, rainfall in most parts of the study area will be likely to decrease, which will help alleviate soil erosion. However, most areas of Sichuan, the Loess Plateau and the Southern Hilly Mountain of China will face the pressure of soil erosion due to an increasing farmland. Considering the reduced rainfall under future climate change, it is recommended to increase the proportion of grassland on the Loess Plateau in order to reduce water consumption, while to maintain surface cover to alleviate water and soil erosion at the same time; in addition, each region still needs to control farmland expansion and takes appropriate measures to manage slope farmland and to reduce soil and water erosion in farmland areas.