退耕还林和地理特征对土壤侵蚀的关联影响——以陕西省107个县区为例

Abstract

在自然要素和社会经济要素交互作用下，科学评估退耕还林工程对土壤侵蚀的影响，对生态修复政策的可持续性具有重要意义。在利用RUSLE模型评估陕西省土壤侵蚀强度时空演变特征的基础上，构建纳入社会经济因素的退耕还林防治土壤侵蚀效应研究框架，基于面板数据固定效应模型，探究地理特征对退耕还林工程防治土壤侵蚀的影响。结果表明：①2000-2015年陕西省土壤侵蚀强度显著降低，全省土壤侵蚀总量由2000年34166.42万t，下降至2015年28260.69万t，区域土壤侵蚀强度及其时空变化特征存在显著异质性，陕北地区土壤侵蚀水平最高，同时下降也最为显著。②退耕还林工程对防治土壤侵蚀有显著的正向影响，表现为投资金额每增加1万元，土壤侵蚀总量下降26.30t，且资金投入的生态效益存在显著滞后效应。③地理特征在退耕还林工程防治土壤侵蚀效应中存在显著调节作用，相较关中和陕南地区，陕北地区退耕还林工程防治土壤侵蚀效应更为显著。坡度和降雨对工程的防治土壤侵蚀效应存在显著负向调节作用，而日照时间则表现出正向调节作用。决策者应充分考虑自然地理因素和社会经济因素对生态系统服务的复合作用机理以实现生态修复政策的可持续性。;In order to respond to the seriously ecological problems caused by soil erosion since the last century, Shaanxi Province has been implementing the Grain for Green project since 1999 as a pilot province. The project has achieved remarkablely ecological benefits in the past 20 years, and the regional soil erosion has also been under effective control. While soil erosion, as one of the important indicators of ecosystem services, is the result of the interaction between natural factors and human factors, so it's significant to assess the impact of the Grain for Green project on soil erosion under the interaction of natural factors and socio-economic factors for the sustainability of ecological restoration policies. Based on the analysis of the spatial and temporal evolution of soil erosion levels in 107 counties of Shaanxi Province using the RUSLE model, this study explored the impacts of geographic characteristics on the prevention and control of soil erosion by the Grain for Green project using the fixed-effect model of panel data. The results showed that:(1) from 2000 to 2015, the level of soil erosion in Shaanxi Province decreased significantly and the total amount of soil erosion decreased from 341.66×10⁶ t in 2000 to 282.61×10⁶ t in 2015. Besides, there was obvious heterogeneity in regional soil erosion intensity and its spatio-temporal variation characteristics. For example, the soil erosion intensity in Northern Shaanxi region was the highest meanwhile the decline was also the most precipitous, while Guanzhong region and Southern Shaanxi region were not. (2) The Grain for Green project had a significantly positive impact on the prevention and control of soil erosion. It showed that for every 10,000 yuan increased in investment, the amount of soil erosion decreased by 26.30 t. At the same time, compared with Guanzhong region and Southern Shaanxi region, the effect of soil erosion control in Northern Shaanxi was more significant. (3) The geographical characteristics had a significant moderating effect on the effect of the Grain for Green project on soil erosion control. Slope and rainfall had a significant regulating effect on the soil erosion control effect of the project, while the sunshine duration showed a positive regulating effect. Policy makers should fully consider the combined mechanism of natural geographic factors and socio-economic factors on ecosystem services to achieve the sustainability of ecological restoration policies.