Karst Ecosystem Health And Assessment Of Southwest Guangxi

Based on the "time-specific" method, the Karst flora of Southwest Guangxi was studied. And succession stage classification was analyzed as well as succession sere and ecosystem health by using the theory and method of Ecology, Mathematics, Statistics, Computer science, and Similarity theory. Results showed that: (1). The forest was characterized with phanerophyte evergreen plants with single-mesophyll-leathery leaves, which reflected the nature of tropical Karst mountainous seasonal rain forest. (2). Community succession was divided into five stages by using Cluster method, PCA method; the succesion stages include herbaceous stage, scrub-shrub stage, small tree stage, arbor stage and climax seasonal rain forest stage. (3). Based on similarity theory, succession sere was constructed with the community similarity equation formed. (4). Ecosystem health assessment indicated that the Karst ecosystem of Southwest Guangxi was under severe stress. As the community energy was concerned, the community biomass was low which was 4.826t/hm2-7.206 t/hm2 at herbaceous stage, 3.2 t/hm2-6.887 t/hm2 at scrub-shrub stage, 40 t/hm2-80 t/hm2 at tree stage, and most ofthem were less than 100 t/hm2. The Karst soil nutrition, containing 5.32%-14.32% organic matter, was higher than other type of soil. However, the humus contained was low (about 1.32%-3.39%). This suggested that the decomposition speed of organic matter was slow. Community biodiversity was high at every stage of the sere, which indicated constant disturbance according to the intermediate disturbance theory. The research also revealed that the restoration of community biomass, community height, community in general needed 35.3a-39.995a, 34.46a-40.64a and 34.01a-39.3a respectively when the restoration degree (RD) reached 0.8-0.9. If the RD got to 0.999, it would take 80.63a, 94.07a, 84.98a.