黄河中游的侵蚀环境与植被恢复前景

黄土高原的土壤侵蚀和生态环境问题世界瞩目。在保证蓄水拦沙效益基础上,提高林、草保存率,使植被恢复得到最佳的生态效益,是黄土高原环境整治中亟待解决的关键问题。本文根据黄土高原不同空间地理位置的流域、重点县水文监测资料,研究了气候、地表覆被、土地利用方式的变化对流域侵蚀产沙的影响以及流域产沙与地理环境要素间的耦合关系,定量分析了黄土高原,特别是多沙粗沙区自然与人文要素对流域侵蚀产沙的综合影响和因子的权重分析,并利用天然降雨植被生态需水适宜性系数和林、草恢复度的概念,重点探讨了黄河中游主要产沙区、尤其是多沙粗沙区退耕还林等土地利用方式宏观格局变化与植被恢复前景。研究表明,在植被生长主要依赖天然降雨的黄土高原,生物措施(植被类型)要与自然带相适应,应根据植被恢复度和植被生态需水适应性系数来进行宏观植被的恢复与实施。这是目前在不断增长的人口压力下,进行水土保持,解决好经济发展与环境保护、减少垦殖率与保证老百姓的基本农田、造林种草与植被类型的自然适应性、以及控制泥沙作用中生物措施与工程措施合理布局等诸多矛盾的关键所在。

The impact of environmental variables on sediment yield and vegetation recovering prospect in the middle Yellow River

Soil erosion and eco-environment on the Loess Plateau are among the most serious problems in the world.To improvements of the vegetation coverage and ecological efficiency are the key issues to be settled urgently in future in the context of erosion control and food security.According to the data from the key counties with different spatial locations on the Loess Plateau,the effects of climate,land cover and land use pattern on sediment yield as well as the relationship between sediment yield and environmental variables are studied in this paper.The integrated impact by natural variables and human activities and their weights in influencing sediment yield are also quantitatively analyzed on the Loess Plateau,particularly in the sandy and coarse sandy areas.Furthermore,the adaptive coefficient of eco-water requirement of natural vegetation and the concepts of restoration degree of forest and grass are used to systematically discuss the macro-configuration changes of land use pattern and vegetation restoration prospect in the middle Yellow River,particularly in sandy and coarse sandy areas.Studies indicate that on the Loess Plateau,where the growth of vegetation mainly depends on natural precipitation, biological measure(mainly vegetation type) is required to be in accordance with natural zone,and the restoration and construction of macro-vegetation should adhere to the vegetation restoration degree and its adaptive coefficient of eco-water requirement.With the pressure of growing population,it is a key problem to reconstruct vegetation and crop planting to settle out the contradictions, such as properly dealing with the relationship of economic development and environmental protection,reducing reclamation rate and protecting farmland,planting forest and making grass and their adaptative to precipitation as well the reasonable configuration of biological and engineering measures on the Loess Plateau.