Ecological Study On Animals In Dayan Cave And No.2. Yantou Cave Of Guangxi Province

A relatively systematical study has been done on cave animals in Yangshuo area, Guangxi Province. Animals in Dayan Cave and No.2.Yantou Cave were chosen to be the objects of the study in which their community structure and their spatial distribution were investigated and analyzed. Through systematical investigation in July of year 2007, 5048 specimens were collected in Dayan Cave and No.2.Yantou Cave of Yangshuo area, subordinating to 35 families, 42 genera, 69species or groups, among which 3324 specimens of cave animals collected in Dayan Cave belong to 26 families, 30 genera, 50 species or groups and 1724 specimens collected subordinate to 29 families, 36 genera, 45 species or groups. According to the animal species and their numbers in different light areas of the two caves, Dayan Cave and No.2.Yantou Cave, six communities were classified as community A, B, C, D, E and F.Community diversity index(H'), evenness index(J'), richness index(D)and similarity index were studied, and so was the correlation between each diversity index and environmental factors. The results of the analysis showed the evenness index gradation of each community from the highest to the lowest was as the following: F(0.9790) > C(0.8392) > B(0.7553) > E(0.7355) > A(0.6970) > D(0.6487). The highest index of richness was community E(6.3717) and D(5.6321). The highest index of diversity was community F(3.0261) and C(2.7694). The similarity index between neighbouring communities in the same cave was higher, especially communities in weak light area and no light area. For example, the higher similarity index was between A-B(0.5437) and between B-C(0.5368). On the contrary, the similarity index was lower between communities in different light areas of different caves or between communities with a longer distance in the same cave. For example, the lower similarity index was between B-E(0.1034) and between A-F(0.0702).The correlation analysis between the environmental factors listed and species with their community diversity showed the following results: S had the significantly positive correlation with AT(温度) and had the most significantly negative correlation with ACO(CO2含量); D had the significant correlation with ACO; H'had the significant correlation with AN(N2含量) and negative correlation with ACO; J'had the significant correlation with AN and negative correlation with ACO; H'max had the significant correlation with AT; H(湿度) had the negative correlation with AO(O2含量); Correlation between other parameters was not significant. The Euclidean Distance between the environmental factors listed and species with their community diversity was calculated and the results of analysis showed that the Euclidean Distance was the smallest between S-D (66.753), S-AO (28.736), D-SOM(the content of organic matter) (8.035), H'-SOM (2.132), J'-AN(1.790).On several animal species in the two caves mentioned above, the remained content of heavy metal, the enrichment index of heavy metal, the correlation between parameters, the Euclidean Distance between parameters and the content of heavy metal in environmental factors were analyzed, the results of which showed that the enrichment index of different heavy metals, the correlation and the Euclidean Distance were different on the same animal species and that the enrichment index of a certain heavy metal, the correlation, the Euclidean Distance were also dissimilar on different animal species.The analysis made towards parameters and factors mentioned above showed: in cavern ecosystem, there existed significant relevance-effect between the structural features of animal community and ecological characteristics of animal community. The remainder and the enrichment of heavy metal in cave animals closely had something to do with the environment and the inter-relevance between or among elements in heavy metal. As for environmental factors, pH had the bigger influence on the accumulation of heavy metal and had different influence on different animals. With the change of seasons and air temperature, the solubility of oxygen and other substances varied. Thus the enrichment of heavy metal inside animals was also affected greatly by temperature and salinity. The content of heavy metal accumulated inside animals had the significant positive correlation with the density of heavy metal in the environment and had something to do with the time-length of the animals'living in such environment. In addition, the accumulation of heavy metal was greatly influenced by the functions of inter-unity and inter-repellency between or among the heavy metal.