【摘要】 根据景观生态学的观点 ,对流域的产沙特征及其与林草植被的关系进行了探讨 ,表明流域土壤侵蚀状况是由其农、林、草地等生态系统之间产流与拦蓄两种作用相互影响的结果 ,其中作为地表径流滞纳区的林草植被斑块起重要作用。林草覆盖率越高 ,植被对侵蚀的绝对控制能力越强 ,否则流域地形因素的影响亦不可忽视。还分析了流域临界林草覆盖率的定义 ,表明临界林草覆盖率随其平均坡度的增大而增大。当流域林草植被整体覆盖率达 50 %以上时 ,植被可稳定高效地抑制水土流失。进一步分析认为 ,利用计算机技术并借助有关图件深入研究植被的空间格局才能完整阐明植被的整体防蚀作用 ,同时探讨植被斑块对富集叠加径流的滞纳作用也是必要的。更多还原

【Abstract】 According to landscape ecology,this paper discusses the characteristics causing silt in a watershed and relations between them and forest/grass vegetation.It is shown that soil erosion situation in a watershed depends on interaction of producing and retaining surface runoff among constituent ecosystems such as farmland,forest,grassland,etc.,of which grass or forest patches as parts taking surface runoff play an important role in soil and water conservation.The larger grass and forest coverage,the stronger the absolute control capacity of vegetation on soil erosion,or influencing factors about topography may not be ignored.This paper also analyses the definition of critical grass and forest coverage.It is indicated that critical grass and forest coverage have high values with large average slopes.If grass and forest coverage in a watershed gets above 50%,generally speaking,vegetation in it may check soil and water loss steadily and efficiently.Based on further analysis,it is considered that by using computer techniques and related maps,intensively researching into spatial pattern of vegetation can integratedly clarify the effect of vegetation as a whole on protecting soil from erosion, and meanwhile it is necessary to make an approach to retaining effect of vegetation patches on concentrated surface runoff which includes the runoff coming from other patches.更多还原