Combating the fragile Karst environment in Guizhou, China.

Karst landscapes—regions characterized by sinkholes, caves, springs, underground rivers, and slowly dissolving bedrock— constitute about 25% of the world’s land surface (1). Although some karst landscapes are attractive and of aesthetic value, most of them are recognized as fragile zones unsuitable as human habitats— mainly due to extremely poor soil cover, or a complete lack of soil, and rapid water loss. China is one of the countries featuring extensive karst areas, with about 23% of its land area, nearly 2 000 000 km, covered by open and covered karst rocks (2). These areas of China are mainly concentrated in the southwest, in the provinces of Guizhou, Yunnan, and Guangxi (Fig.1). About 73.6% of the total area of the province of Guizhou is made up of karst landscapes. For this reason, Guizhou has been named the ‘‘Karst province’’ of China (3). Due to the extremely fragile environment and the existence of a large number of underground caves, it is much more difficult and expensive to build roads and highways in karst areas than in other areas. This has confined Guizhou province in an almost closed state for a long time in history. Development of the province has therefore been seriously limited. On the other hand, there is a large human population in the karst areas of the province, with a population density as high as 185 persons per km . In contrast, karst areas in other regions of the world are seldom populated (4). There is thus great population pressure on the karst environment in Guizhou. As a result, Guizhou province has long been one of the poorest provinces in China. In many counties of the province, the per capita income has been below 1000 Chinese yuan (8 Chinese yuan ’ USD 1.00) (5). As a result, the Chinese have a saying about Guizhou; ‘‘There is no one piece of flat land that is wider than 3 inches, and there is no one people whose money is more than 3 fen (1 Chinese yuan 1⁄4 100 fen).’’ In addition there has been an occurrence of detrimental human activities, e.g. over-logging and steep-slope farming, in the province. This is mainly due to overpopulation and extreme poverty. As a consequence there has been a decrease in vegetation cover, forest and shrub in the karst areas; surface soil has deteriorated due to intensified soil erosion; and larger and larger surface areas have become nearly naked. The stones seem to ‘‘have grown,’’ as the local people say. This process of degradation of karst ecosystems is called ‘‘rock-desertification’’ (Shi Mo Hua) in Southwest China (3). Owing to the enormous difficulty in managing and controlling this phenomenon, rock desertification in karst areas is also called the ‘‘cancer of the earth’’(3). In recent years, ecologists and geographers, together with the local people, supported mainly by various levels of government, have undertaken work to combat further degradation of the fragile karst environment; e.g. selecting adequate tree species, forest plantations, and developing models in order to control rock desertification as well as promoting development of the local economy. Some progress has been made and is described in what follows.