长白山苔原带土壤动物群落结构及多样性研究

Abstract

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.