长白山苔原带土壤动物群落结构及多样性

长白山苔原生态系统对环境变化非常敏感,一旦破坏很难恢复。土壤动物是陆地生态系统的重要组成部分,联系着地上和地下生态系统。为探讨长白山苔原带土壤动物群落的组成、结构和多样性特征,于2009年5月、7月和9月对上部和下部苔原带土壤动物进行了研究。研究表明:长白山整个苔原带土壤动物优势类群为甲螨亚目、节跳虫科和球角跳虫科。下部苔原亚带土壤动物个体数和类群数多,群落结构较为复杂。土壤动物的个体数随生境和时间变化有很大波动,类群数变化则较小。在7月份个体数最少,而类群数随着时间的变化有减少的趋势。土壤动物的垂直分布随时间和生境的不同而异。上部苔原亚带9月的甲螨亚目(P﹤0.01)、革螨亚目(P﹤0.05)及下部苔原亚带5月的甲螨亚目、革螨亚目、辐螨亚目(P=0.03,P=0.011,P=0.027)0—5 cm土层显著高于凋落物层;下部苔原亚带5月的球角跳虫科(P=0.001)及各月的节跳虫科和山跳虫科在各层之间存在显著差异(P=0.001,P=0.036,P=0.005,P=0.001,P=0.04,P=0.009)。两个亚带土壤动物多样性随时间的变化都有递减的趋势。土壤动物的多样性指数、丰富度指数和均匀度指数均是下部苔原亚带高于上部苔原亚带,而优势度指数则相反。相似性指数表明两个亚带土壤动物群落组成上存在一定的差异,各类群的相对数量差异在9月最大。下部苔原亚带的生境条件较适宜土壤动物生存,生物多样性较高。

Structure and diversity of soil fauna communities in the tundra of the Changbai Mountains, China

The ecosystem of the Changbai Mountains is the sentitive natural succession or to environmental change after volcanic eruption. Once the ecosystem of the Changbai Mountains, which has a thin soil layer, is damaged, it is difficult to restore. Soil fauna, an important component in terrestrial ecosystems, is closely connected with the above and under ground ecosystems and plays an important role in terms of material circulation and energy flow. In addition, soil fauna has a certain response to the changes in environmental factors, such as vegetation and soil. An investigation was carried out in both the upper and lower tundra of the Changbai Mountains, during May, July, September 2009, to study the characteristics of composition, structure and diversity of soil fauna. This can provide a scientific basis for the conservation and sustainable development of the Changbai Mountains ecosystem.On each sampling visit, soil macrofauna and meso-microfauna were collected in both the upper and lower tundra using a sampling quadrat of sizes 25 cm×25 cm and 10 cm×10 cm, respectively. Six repeat sampling quadrats were set up in both the upper and lower tundra and litter layer at depths 0-5 cm, 5-10 cm, 10-15 cm in each quadrat. Soil macrofauna were picked by hand-sorting methods in sample plots, while the soil meso-microfauna were collected by modified Tullgren. The results showed that the dominant groups were Oribatida, Isotomidae and Hypogastruridae. The soil fauna community structure in the lower tundra, which possessed higher individual and group numbers, was more complicated. The individual number was influenced by the habitat characteristics of the research zones and fluctuated with the seasons, while the group number did not change significantly. In both of the subzones, the individual numbers of soil fauna were lower in July, while the group numbers had a tendency to decrease. Both the habitat and season had a significant effect on the vertical distribution of different soil fauna. In the upper tundra, the individual number of Oribatida (P < 0.01) and Gamasida (P < 0.05) in September in the 0-5 cm soil layer were higher than those in the other layers. In May, Oribatida, Gamasida and Actinedida (P=0.03, P=0.011, P=0.027) in the lower tundra had the same distribution pattern. Distinct differences existed in the vertical distribution of Hypogastruridae (P=0.001) in May and Isotomidae and Pseudachorutidae in May, July and September in the lower tundra(P=0.001, P=0.036, P=0.005, P=0.001, P=0.04, P=0.009). The diversities of soil fauna of both subzones had a decreasing tendency with time changes. The diversity index, Margalef index and Pieluo index of soil fauna in the upper tundra were lower than those in the lower tundra, while the Simpson index in the upper tundra was higher. Comparison of the similarity index showed that the soil fauna community composition was different between both subzones. The quantity variance in different soil fauna was greatest in September. All the results detailed above showed that the lower tundra with the better habitat conditions is more suitable for soil fauna survival, so that there is a higher biodiversity than that of the upper tundra.