Biodiversity Of Karst Tiankeng In South China

As a rare negative terrain in the surface,karst tiankeng's unique traps habitat and biodiversity has not got the systematic research and aroused the attention.This paper takes the plant species diversity investigation which is more operational than animal or microorganism diversity investigation as the entry point,choosing the Zhanyi karst tainkengs in Yunnan which own both the primordial and degenerate tiankengs as the study area.A total of 10 tiankengs and dolines were investigated,and 1 primordial tiankeng,1 degenerate tiankeng,1 degenerate doline among them was selected for the study.With the application of the R language software,SPSS statistical software,ADE4 point pattern analysis software,Winkelmass spatial structure analysis software,the alpha,beta diversity index,species forest spatial structure parameters,species indicating value,the edge effect value index and the edge effect intensity were calculated to do the study on the species diversity and spatial distribution characteristics of the plant communities in karst tiankeng.The research purpose was to reveal the unique biodiversity conservation base value,species refuge value and the value of biodiversity of world natural heritage of karst tiankeng,and provide some benefit references on the ecological habitat restoration work,vegetation succession and biodiversity protection work for the region of Yunnan plateau karst ecological fragile region,nature reserves and other areas in China that has the similar habitat.The results showed that:(1)there is big difference on the species composition of arborous layer and shrub layer plant between the inside and outside of primordial tiankeng,the vegetation type of inside area is subtropical humid evergreen broad-leaved forest,and of outside area is the subtropical semi humid mixed coniferous and broad-leaved forest,so the special ecological environment of tiankeng has the important value of species protection;(2)the spatial distribution of the plant community in the bottom of primordial tiankeng presented the random distribution characteristics,but the populations were showed the aggregated distribution,the minling intensity of species showed the medium mixed,and although the vertical stratification was relatively simple,the structure was stable,which possessed the trait of a mature climax forest community;(3)the cliff was a special ecotone of the inside and outside ecosystem of tiankeng,and the species richness presented a negative edge effect on the tiankeng cliff,although the ecotone appeared on the middle position of tiankeng cliff,there was not showed the"mid-domain effect" between the plant species diversity and the vertical gradient variation,and without any special rules;(4)the herb species diversity in the bottom of degenerate tiankeng showed a "negative depression effect" from the center to the edge which is the same as the distribution of arbor in the primordial tiankeng,but the shrub in the primordial tiankeng showed a contrary law that presented a"depression effect";(5)the plant distribution showed a "circle effect" in the bottom of the degenerate tiankeng,the herb close to the center circle is the thermophyte,and with the higher species richness and diversity in side with higher cliff wall,the species close to the edge circle is ombrophyte,and with the higher value in the side that with the lower cliff wall.