多尺度土地利用与土壤侵蚀

土地利用能够通过改变一系列的自然现象和生态过程影响土壤侵蚀，尺度不同，土地利用与土壤侵蚀的作用机制也会发生变化。本文针对坡面尺度、小流域／流域尺度和区域尺度，综述了不同尺度上土地利用对土壤侵蚀的影响研究。其中，在坡面尺度上，土地利用与土壤侵蚀的研究主要包括土地利用方式和土地管理措施对土壤侵蚀的影响，相应尺度上的模型有USLE／RUSLE、WEPP等；在小流域／流域尺度上，土地利用与土壤侵蚀的研究主要涉及土地利用结构和土地利用格局对土壤侵蚀的影响，相关的模型有LISEM、AGNPS、EUROSEM和SEDEM等；在区域尺度上土壤侵蚀评价研究主要是通过尺度上推和宏观因子评价的方法进行。多尺度土地利用与土壤侵蚀研究作为自然地理学研究中的热点问题，在进一步的研究中需要关注多尺度综合与尺度转换、土地利用政策效应、土地利用格局与土壤流失过程等方面的研究内容。

Land Use and Soil Erosion at Multiscale

Improper land use by mankind is one of the main causes of soil erosion. Through changing vegetation cover, soil property and runoff velocity, land use affects the occurrence and development of soil erosion. As scale changes, notable changes will occur in the interactive mechanisms between land use and soil erosion. Currently, research on land use and soil erosion is changing from slope scale to small watershed, watershed, and regional scales. Examining the influence of land use on soil erosion at different scales has become a frontier field in contemporary research in physical geography. At slope scale, vegetation offers protection against soil erosion by reducing runoff and increasing soil resistance to sediment entrainment. Research has verified that the effects of different land use types on soil erosion vary obviously, and farmland may be the most susceptible land use to runoff and soil erosion for different areas. Land management practices, such as changing micro-terrain, exert important influence on soil erosion, and the common soil erosion models used at slope scale are USEL/RUSLE and WEPP. At small watershed scale(or watershed), more attentions are paid to the impacts of land use structure and land use pattern on soil erosion. There is correlation between some land use types and sediment yields, and changes in land use structure have a significant impact on soil erosion. The spatial variability of land use pattern may change the interception ability of land parcel, the hydrological structure and soil erosion systems, which impact the final sediment load at watershed scale. In order to identify the relationship between land use pattern and soil erosion, some distributed soil erosion models are often applied to simulate soil erosion rate under different land use patterns, such as LISEM, AGNPS, EUROSEM and SEDEM. At regional scale, there are some methods to carry out soil erosion evaluation. One way is by means of up-scaling methods to study soil erosion of large area. The up-scaling methods include: combining the monitoring data at related gauges in the region, and using soil erosion model at slope, small watershed scale or watershed scales for regional scale. The other way is to select some macro-factors for soil erosion evaluation. Land use has an important impact on soil erosion, and impacts of land use on soil erosion have been regarded as a hotspot and leading issue in scientific research of physical geography. There is a long run to go for land use and soil erosion, though great progress has been achieved so far. More attentions may be paid to scaling, effects of land use policy, land use pattern, soil loss process, and etc.