Effects of Snow Thickness on Several Cultivable Bacterial Physiological Groups in the Soil Organic Layer under an Alpine Forest at Later Freezing-thawing Season

Global climate change is affecting the alpine snow cover pattern. In this context, different snow depths of natural snow patches surely will affect soil temperature and humidity strongly, which retained strong effects on the soil microbial community structure and microbial activity. However limited information is available on soil ecological process driven by microorganisms and what will come of this process under the effects of these complex factors have not demonstrated. The effects of snow thickness on the characteristics of cultivable bacteria and bacterial physiological groups in the soil organic layer of Abies faxoniana forest were studied by using the plate culture method and the most probable number method, which have been used widely in measuring numbers of specific microbial physiological groups. Snow thickness significantly influenced the numbers of bacteria and its physiological groups in the organic layer, while in the every soil layer, there is obvious difference respond between the snow cover and the bacteria and its physiological groups. In general, the numbers of ammonifying bacteria, nitrifying bacteria and anaerobic cellulose decomposing bacteria are relatively more under the thickest snow patch than under the other patches. With the deepening of snow thickness, the number of denitrifying bacteria reduced. Meanwhile, aerobic cellulose decomposing bacteria number showed no significantly changes. The overall trend for the numbers of bacterial physiological groups was: ammonifying bacteria > denitrifying bacteria > nitrifying bacteria > aerobic cellulose decomposing bacteria > anaerobic cellulose decomposing bacteria. The results provides important theoretical and scientific basis for understanding the seasonal transition of soil ecological process in the alpine forests under climatic backgrounds.