Sustainable development of agriculture in karst areas, South China

The exposed carbonate rocks aged from Sinian to Mid-Triassic Periods cover an area of 500,000 km2 in south-west China. In karst areas with spectacular landscapes characterized by magnificent tower karst and conical karst, rare surface drainage systems and prevalent subsurface drainage systems, the environment is ecologically very fragile. The rapid increase of population, over deforested and cultivated lands, worsted the ecological system, causing a higher frequency of draught, flood and various disasters, backward economic development, low living standard of the people. In order to improve the sustainability of the agriculture the experience shows that the following operations should be adopted: (1) serious control of the population increase, emigration, extra labours and improvement of the environmental education of the local inhabitants; (2) terracing of the slopes (shi jala di) as to improve the cultivated land quality, to preserve the water, soil and fertiliser and ameliorate the effective utilisation of the land; (3) development of new rural energies such as the solar energy and gas energy, and expansion of the saving-fuel stoves to reduce the load of bio-energy; (4) reforestation and bounding the hills and mountains; the ecological, economic and fuel forests model has been developed in fengcong-depression areas: the tree species with high ecological, economical and energetic characteristics, should be chosen, such as the bamboo, wild grapes, Sapium rotundifolium etc.; (5) better utilisation of the ram water and karst water resource to solve the water supply problems. The karst landscape is well developed in the 500,000 km2 carbonate terrain in Yunnan, Guizhou, Guangxi, west Hunan and south Sichuan provinces in south-west China, where 100 million habitants live (Song, 1997). The large population and its high density, serious deforestation, over-cultivation and fragile ecological system make the environmental problems very serious and about 30,000,000 people are now very poor. This paper describes the measures to improve the ecological and sustainable development of the agriculture in the karst areas