Land Use/Cover Change In Ecologically Fragile Karst Areas

It is well known that karst areas are typically ecologically fragilie. The Southwestern China is the centre of East Asia Karst Area, which is one of the three biggest karst areas around the world, where soluble rocks (mainly carbonate rocks) cover a area of 540 000km2, and about 0.1 billion people live. Over the past few decades, land use changes there have brought forth a series of severe ecological and environmental problems, which directly threaten the sustainable development of local society and economy and also the ecological security of nearby areas. Although some academic achievements have been made on the issues, it is far from enough. Employing the satellite images of Landsat-MSS and Landsat-TM and the integrated techniques of RS, GIS, and GPS, the authors, with Maotiaohe River Basin as a case, studied the process and driving factors of land use /cover changes since the beginning of 1970s, and modeled the possible land use/cover changes scenarios in the coming 10 years based on CLUE-S model, and then made an ecological evaluation on effect of the changes over the past 30 yeas as well as in the coming 10 years by using theory and method of landscape ecology. In this research, the authors, from the angle of international LUCC studies, threw much light on the land use/cover changes in the basin and also the derived ecological and environmental problems such as karst rocky desertification. The study shows that:⑴Over the past 30 years, land covers in Maotiaohe River Basin have experienced dramatic change. In quantitative terms, from the year of 1973 to 1990, the absolute change extent obey the following sequence: dry field (8.61%) > shrub land (-7.06%) > paddy field (-3.52%) > naked land (2.12%) > tea land (-1.92%) > forest land (1.06%) > grassland (-0.61%) > rural settlement (0.58%) > traffic and industrial land (0.53%) > water (0.1%) > urban land (0.06%); and from 1990 to 2002, dry field (-9.79%) > grassland (3.33%) > forest land (3.18%) > paddy field (1.98%) > naked land (-1.45%) > rural settlement (0.85%) > shrub land (0.73%) > water (0.48%) > traffic and industrial land (0.47%) > urban land (0.27%) > tea land (0)⑵From the year of 1973 through 2002, the cultivated land increased and then decreased. The paddy field decreased in 1970s and 1980s and then increased after 1990, in 1973, 1990, and 2002, the percentage of paddy field in the whole catchment is respectively 18.54%, 15.02%, and 17.00%; meanwhile, dry field experienced opposite change with the percentage respectively 22.41%, 31.02%, 21.23%. The forest land kept on expanding over the past 30 years with the 1990s as a...