The Da Hinggan Mountains are located in the cold-temperate zone, low in temperature and the soil is of the faint acid soil type. This kind of environment limited the development of soil fauna and microorganism. Spraying of effective microorganisms (EM) and lime can increase the activities of microorganisms and lower the acidity of soil, respectively. In this paper, canonical correspondence analysis (CCA) is used to analyze the relationship between soil fauna dynamics and the pH and organic matter dynamics. Distinct difference exists in soil pH value under treatment of lime 1 and lime 2 (P=0.001, F=19.94, df=15; P=0.043, F=4.94, df=15) and great difference appeared in soil organic matter under treatment of EM 1 and EM 2 (P=0.001, F=19.56, df=15; P=0.048, F=4.71, df=15). It shows that the experiment meets the original research aim.
From June 2003 to Oct. 2005, lime and EM treatment were used to change the faint acid soil and microorganism activities. Fluctuation of soil fauna community was studied during the defoliation decomposition process in Da Hinggan Mountains by litterbags. It shows that: (1) In total, there are 73038 soil animals, belonging to 3 phyla, 6 classes and 20 orders. Among them, Mesostigmata, Prostigmata, Isotomidae and Oribatida are dominant groups. Entomobryidae, Pseudachorutidae, Onychiuridae and Sminthuridae are common groups, while the others are rare groups. The group number and DG biodiversity index reduced, but in individual number increased under lime and EM treatment. The individual number is influenced by the climatic character of the research zone and fluctuated with seasons. The group number and DG index fluctuated with seasons, lower in June, but higher in August and October. The discipline was not changed under lime and EM treatment. (2) Soil fauna had staged feature during defoliation decomposition in treated plots. And the succession index of each group was different in each plot. The succession indices of dominant and common groups were longer than others. There are 4 colonization types of soil fauna. Type Ⅰ is made up of Mesostigmata, Onychiuridae, Tomoceridae, Entomobryidae, Lithobiomorpha and Hypogastruridae, and most of them are dominant and common groups. In different stages, most of them had distinct advantages. Type Ⅱ is made up of Prostigmata, Sminthuridae, Staphylinidae, Chironomidae and Oncopoduridae, colonizing in the early stage of defoliation decomposition. Type Ⅲ included Isotomidae, Oribatida, Pseudachorutidae, Carabidae, Staphylinidae larva and Corrodentia, appearing at the last stage of defoliation decomposition. Type Ⅳ is made up of those appearing only at middle stage of defoliation decomposition. They are low in number and basically rare groups. (3) Canonical correspondence analysis showed that soil pH and organic matter were important factors to affect fluctuation of soil fauna community. Mesostigmata, Prostigmata, Isotomidae, Oribatida, Entomobryidae, Pseudachorutidae, Onychiuridae, Tomoceridae and Lithobiomorpha had better adaptation ability to soil pH and organic matter changes. As the decomposer, soil fauna maybe have influence on defoliation decomposition process and further influence the cycling of nutrition and materials under lime and EM treatment.