Seasonal dynamics of soil microbial biomass C shows close correlation with environmental factors in natural Fagus crenata forests

摘要

Soil microbial biomass (C-mic) is an important factor regulating a number of ecosystem processes. In this study, we investigated seasonal variations in soil microbial biomass in natural climax beech (Fagus crenata) forests in a typical cold-temperate mountain region of Japan. Four permanent tower sites along an altitudinal gradient were selected and soil samples were collected once every month during the growing season of 2007. Soil microbial biomass (by fumigation-extraction method) and soil properties were later measured in the laboratory, while environmental factors (soil temperature, soil moisture) were continuously recorded in the field. Our results indicated large seasonal variations (130.4 similar to 5558.0 mu g g(-1)) in soil microbial biomass in beech forests - a range that is much larger than previously reported. Statistically significant correlations are noted between soil properties with C-mic, but largely due to spatial linkages. On the other hand, the environmental factors of soil temperature and especially soil moisture largely control seasonal variations in C-mic. Furthermore, pH could be an important factor influencing seasonal change in C-mic at the 20-30 cm deep soil layer. The study suggests no direct correlation between plant eco-physiology and soil microbial biomass in seasonal courses of the forests.