KARST ECOSYSTEM CONSTRAINED BY GEOLOGICAL CONDITIONS IN SOUTHWEST CHINA

Abstract

Karst ecosystem is an ecosystem controlled by karst environment. In Southwest China, carbonate rocks are mainly distributed along the NE-extending tectonically upheavedzone, deeply impacted by geological background. Based on the statistics data, 292 karst counties whose carbonate rocks are 30% higher than the lands, with respect to their distribution area. And particularity and fragibility of the karst ecosystem can be summed up as follows: (1) Soil and water resources are of shortage and out of coordination. In other words, underground water is an essential water resource, accounting for 41%-83% of the total. Meanwhile, the formation of limestone soil is slower. (2) Guangxi is a typical karst region. A large difference is noticed in vegetation coverage between karst regions and non-karst regions. The average coverage of bush and forest communities is 14.81% and 12.13% in the karst regions, 1.92% and 31.3% in the non-karst regions. (3) The wide distribution of rocky desertification in Guizhou Province indicates the karst environment is strongly affected by carbonate rocks' properties. (4) The fragibility of the karst ecosystem results in its lower population-carrying capacity. We can find the population density of karst counties in Guangxi, Hunan, Hubei and Chongqing is only 85.05%, 83.03%, 46.78%, and 54.43% in non-karst counties and average GDP per person and average income per peasant are also low in these karst counties. On the other hand, Guizhou Province is a center where carbonate rocks are most distributed in Southwest China, and its average gross domestic product (GDP) is obviously lower than that of the surrounding provinces. Great attention should be paid to the relationship between vegetation coverage and water cycle in epikarst zones, the relationship between land-use and underground water protection and the relationship between karst geochemistry and sustainable development in Southwest China.