黄土高原生态工程的生态成效

黄土高原是世界上水土流失最严重的地区,也是我国水土保持和生态建设的重点地区。20世纪80年代以后,国家在该地区先后开展了小流域治理工程、水土保持重点工程、退耕还林(草)工程、淤地坝建设和坡耕地整治等一系列生态工程,对土壤侵蚀控制、生态建设等均起到了良好作用。为全面评价该地区生态工程的生态成效,以野外站不同尺度监测及生态系统关键过程长期研究为基础,利用多种模型和统计分析方法,在地块—小流域—行政区和典型生态工程—典型样区—侵蚀和地貌区等不同尺度上,对土地利用和植被覆盖变化、土壤侵蚀动态变化、河流径流和输沙量动态变化以及社会经济结构动态变化进行了综合分析与评估。结果表明,黄土高原地区水土流失范围明显缩小、水土流失程度显著减轻,区域生态状况向良性发展、社会经济发展迅速。但局部地段(如陡坡耕地)水土流失仍然严重、生态环境仍然比较脆弱,治理形势依然严峻。据此,从该地区生态建设的内容、学科建设重点、监督和政策机制、产业结构调整等方面提出了该地区生态工程后期建设的方向和对策。

Ecological Effects of Soil Conservation in Loess Plateau

The Loess Plateau is the most serious area for soil and water loss (SWL) in the world, and is the key area for soil and water conservation and ecological construction in China. A series of projects, including the Small Watershed Management Project, Soil and Water Conservation Key Project, Grain for Green Project, Check Dam Construction Project, and the Slope Farmland Regulation Project, have been carried out in this area since 1980s. Soil and water erosion was controlled and the ecosystem was restored gradually due to those projects. In order to evaluate the ecological effect for those projects, the dynamics changes of land use and vegetation cover, soil erosion, runoff, sediment transport amounts, and social economic structure were analyzed in different scales from plots-small watershed-region based on model building and long-term position monitoring for ecological processes of field stations. The results showed the ecological environment improved significantly, the area and intensity of SWL veduced greatly, and while the social and economic developed rapidly. while serious loss of soil and water still occurred at some plots or areas, and thus ecological restoration and management are needed urgently. The direction and strategy were suggested including ecological building, discipline construction, policy management, and industrial structure adjustment for the incoming ecological projects.