三北工程区植被恢复对土壤风蚀的影响及植被恢复潜力研究

三北地区是我国重要的生态屏障，分析2000—2019年三北防护林体系建设工程（简称：三北工程）区植被恢复时空变化状况，厘定人类活动与气候要素对植被恢复的贡献，探究植被恢复对土壤风蚀影响，评估植被恢复潜力空间，可为三北防护林体系建设工程未来规划管理和科学施策提供参考。本文在选取植被覆盖度和植被净初级生产力表征植被恢复状况基础上，利用地面数据，结合模型模拟，定量评估了2000—2019年三北防护林体系建设工程区植被恢复程度及其对土壤风蚀的影响，并对植被恢复潜力进行探究。研究结果表明：① 2000—2019年植被恢复程度高、较高的面积，占总面积的35.29%和13.16%，主要分布在黄土高原区及北部区域和风沙区与东北华北平原农区的部分地区。人类活动与气候因素对植被恢复贡献率为10.45%和89.55%；② 土壤风蚀以轻度侵蚀和微度侵蚀为主，呈逐年下降趋势，剧烈侵蚀面积减少了66.45%，防风固沙服务得到进一步提升。植被恢复程度与土壤风蚀模数呈负相关关系，植被恢复程度较好有助于降低土壤风蚀模数；③ 三北工程区森林、草地和荒漠生态系统仍有8.16%的恢复潜力，内蒙古高原北部部分地区、哈顺戈壁北部和准噶尔盆地西北部及周边区域、黄土高原南部部分区域存在较大恢复潜力。

Effect of Vegetation Restoration on Soil Wind Erosion and Vegetation Restoration Potential in The Three-North Afforestation Program

The Three-North Afforestation Program (TNAP) is an important ecological barrier in China, a great green wall has been built to resist sandstorms, conserve water and soil, protect agriculture, and promote animal husbandry in the north of China. In 1978, China began to build the Three-North Afforestation Program. After nearly 40 years of construction, the ecological environment has been greatly improved. However, most areas of the TNAP have sparse vegetation, insufficient annual precipitation, large evaporation, strong wind, serious desertification, and an extremely fragile ecological environment. Therefore, the ecological problems are still very prominent in some areas, and the task of ecological construction still has a long way to go. Analyzing the temporal and spatial changes of vegetation restoration in the TNAP from 2000—2019, determining the contribution of human activities and climate factors to vegetation restoration, exploring the impact of vegetation restoration on soil wind erosion, and evaluating the potential space of vegetation restoration can provide a significant reference for the future planning, management, and scientific implementation of the TNAP. In this paper, we chose the vegetation coverage and vegetation net primary productivity as the index to indicate the vegetation restoration status. Using ground data and model simulation to evaluate the degree of vegetation restoration and its impact on soil wind erosion from 2000—2019. This paper also explored the vegetation restoration potential based on the zonal climax background in the TNAP. The results showed that during 2000-2019: (1) The areas with high and higher degree of vegetation restoration accounted for 35.29% and 13.16% of the TNAP, respectively, which were mainly distributed in the Loess Plateau area, and on the north area of Loess Plateau area, and some areas of the sandstorm area and agricultural area of the Northeast-North China Plain. The vegetation restoration was mainly affected by climate factors in TNAP. The contribution rates of human activities and climate factors to vegetation restoration were 10.45% and 89.55%, respectively; (2) The main soil wind erosion degrees were mild erosion degree and micro erosion degree in the TNAP. The soil wind erosion modulus showed a downward trend year by year. The area of severe erosion has decreased by 66.45%, and the service of wind prevention and sand fixation has been further improved. The degree of vegetation restoration had a negative correlation with soil wind erosion modulus. A better degree of vegetation restoration would be helpful to reduce soil wind erosion modulus and reduce the harm of wind erosion; (3) The forest ecosystem, grassland ecosystem, desert ecosystem still had a restoration potential of 8.16% in the TNAP. Some areas in the north of Inner Mongolia Plateau, the north of Hashun Gobi, the northwest and surrounding areas of Junggar Basin, and the south of Loess Plateau had great restoration potential.