喀斯特洞穴小型土壤节肢动物多样性

Diversity of cave soil microarthropod in karst region

研究洞穴土壤节肢动物,有助于了解土壤节肢动物对特殊环境的响应,对于深入认识喀斯特生态过程具有重要意义。以喀斯特洞穴生态系统小型土壤节肢动物为研究对象,采用主成分分析、重复测量方差分析、相关性分析和冗余分析等方法探讨了小型土壤节肢动物与环境因子的相互作用关系。调查共获得小型土壤节肢动物2399个,隶属7纲15目121科。其中,自然林优势类群为等节跳科(Isotomidae),洞穴优势类群为奥甲螨科(Oppiidae)。PCA分析显示,洞穴与自然林小型土壤节肢动物群落组成差异明显。洞穴小型土壤节肢动物类群数、密度和Shannon-Wiener指数(H′)显著低于自然林(P<0.05),自然林小型土壤节肢动物类群数、密度和Shannon-Wiener指数(H′)季节差异显著(P<0.05),洞穴类群数、密度和Shannon-Wiener指数(H′)季节差异不明显。相关性分析结果表明,小型土壤节肢动物类群数和Shannon-Wiener指数(H′)与pH值、全磷和光照强度显著相关(P<0.05),密度与pH值、全磷、有机质和光照强度显著相关(P<0.05)。RDA分析表明,土壤pH值是影响小型土壤节肢动物多样性的最主要因子。研究结果表明,小型土壤节肢动物多样性受生境类型的影响,洞穴生态系统生境脆弱,稳定性差,不利于小型土壤节肢动物的生存。因此,应该加强洞穴生物多样性保护,避免不合理的开发利用。

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.