Abstract:Karstic cave is a special closed ecosystem, with environmental condition significantly distinct from common ecosystem types, and it is considered an ideal place to study karst ecological processes. Soil arthropod is a critical component of terrestrial ecosystem, and highly sensitive to environmental changes and even small variation in ambient environmental condition has severe consequence on their community composition and diversity, so exploring the cave soil arthropod is helpful to understand the response of soil arthropod to special environment, and is of great significance for better understanding of ecological processes in karst areas. In this study, two habitats types (cave and natural forest) were selected in south Guizhou and soil microarthropod were investigated using Tullgren methods in May, July, October 2018 and January 2019, and principal component analysis(PCA), Repeated measures ANOVA, Pearson's correlation test and redundancy analysis (RDA) were used to examine the interaction between soil microarthropod and environmental factors. A total of 2399 soil microarthropod specimens were captured and classified into 7 classes, 15 orders, and 121 families. Among them, the dominant group was Isotomidae in natural forest, Oppiidae in cave, accounting for 12.09% and 20.79% of the total density, respectively. PCA demonstrated that the structural composition of soil microarthropod communities differed markedly between the cave and natural forest. The group number, density and Shannon-Wiener index(H') in the different habitats showed that these indicators were significantly lower in the cave than those in the natural forests (P<0.05). The group number, density and Shannon-Wiener index(H') of the soil microarthropod had an obvious seasonal variation in natural forests (P<0.05), while these indicators in the cave showed no significant seasonal fluctuation. Pearson correlation analysis indicated that group number and Shannon-Wiener index(H') of the soil microarthropod were significantly correlated with pH, TP and light intensity, and density was correlated significantly with pH, TP, SOM and light intensity (P<0.05). RDA revealed that pH value was the main environmental factor affecting the diversity of the soil microarthropod community. All results showed that diversity of soil microarthropod is significantly influenced by habitat types. Cave ecosystem is extremely fragile, unstable and unfavorable for soil microarthropod survival. Therefore, we should strengthen protection of cave biodiversity, and avoid unreasonable development and utilization of cave.