[Quantitative estimation of vegetation cover and management factor in USLE and RUSLE models by using remote sensing data: a review].

Soil loss prediction models such as universal soil loss equation (USLE) and its revised universal soil loss equation (RUSLE) are the useful tools for risk assessment of soil erosion and planning of soil conservation at regional scale. To make a rational estimation of vegetation cover and management factor, the most important parameters in USLE or RUSLE, is particularly important for the accurate prediction of soil erosion. The traditional estimation based on field survey and measurement is time-consuming, laborious, and costly, and cannot rapidly extract the vegetation cover and management factor at macro-scale. In recent years, the development of remote sensing technology has provided both data and methods for the estimation of vegetation cover and management factor over broad geographic areas. This paper summarized the research findings on the quantitative estimation of vegetation cover and management factor by using remote sensing data, and analyzed the advantages and the disadvantages of various methods, aimed to provide reference for the further research and quantitative estimation of vegetation cover and management factor at large scale.

[Effects of land use type on diurnal dynamics of environment microclimate in Karst zone].

In June 2007, the diurnal dynamics of light intensity, air temperature, air relative humidity, soil temperature, and surface soil (0-5 cm) water content of five land use types in the typical Karst zone of Lingyun City in Guangxi Zhuang Autonomous Region were observed. The results showed that different land use types altered the composition, coverage, and height of aboveground vegetation, which in turn changed the environment microclimate to different degree. The microclimate quality was in the order of forestland > shrub land > grassland > farmland > rock land. On rock land, the light intensity, air temperature, air relative humidity, soil temperature, and soil water content were higher, and the diurnal variation of the five climatic factors was notable, with the microclimatic conditions changed towards drier and hotter. Compared with those on rock land, the light intensity on forestland, shrub land, grassland, and farmland decreased by 96.4%, 52.0%, 17.0% and 44.2%, air temperature decreased by 30.1%, 20.2%, 12.7% and 17.8%, air relative humidity increased by 129.2%, 57.2%, 18.0% and 41.2%, soil temperature decreased by 11.5%, 8%, 2.5% and 5.5%, and soil water content increased by 42.6%, 33.2%, 15.7% and 14.0%, respectively. The five climatic factors on forestland and shrub land had lesser fluctuation, with the microclimate tended to cool and wet. Light intensity, air temperature, and soil temperature correlated positively with each other, and had negative correlations with air relative humidity and soil water content. A positive correlation was observed between air temperature and soil water content.