Microclimate effects of different land use types in demonstration areas for combating karst rocky desertification

Different land use types on two typical geomorphological units of karst,plateau mountain and plateau valley,were studied,which can help to reveal the relationship between vegetation restoration and microclimate change by different land use types,and to provide the theoretical basis for in tegrated control of rocky desertification in karst region.Data were collected by regular microclimate monitoring.Daily variation of atmospheric temperature,light intensity,relative humidity and soil temperature on four land use types were analyzed before the rainy season (April),during the rainy season (August) and after the rainy season (December) in the two study areas.The results showed that,(1) Among the four land use types,atmospheric temperature,light intensity and soil temperature were in the order of rocky desertification bare land > farmland > shrubbery > forest land,while the relative humidity was on the contrary,i.e.forest land > shrubbery > farmland > rocky desertification bare land.This indicated that the forest land performs the best in microclimate regulation,and the rocky desertification bare land performs the worst,which corresponds to the rocky desertification control and vegetation restoration.(2)In the plateau mountain,atmospheric temperature,light intensity and relative humidity were significantly higher than the plateau valley in all seasons and land use types,while soil temperature of different soil layers in the plateau mountain was significantly lower than the plateau valley.(3)Seasonal differences on microclimate of different land use types was clear.Atmospheric temperature and soil temperature were in the order of rainy season (August) > before the rainy season (April) > after the rainy season (December),while the light intensity and relative humidity were in the order of the rainy season (August) > after the rainy season (December) > before the rainy season (April).Each index of microclimate reached to the highest value in August.The discrepancy of these values among the different land use types and different control areas was also the most significant in August.Therefore,microclimate monitoring in August to compare the difference among the different land use tvpes and different control areas is more effective than the other two months,i.e.April and December.