Abstract: In January 2008, an extraordinarily serious snow storm and freezing disaster occurred in southern China, giving obvious impacts on the ecosystem proce
sses via altering the resources availability and heterogeneity. Taking the Moso bamboo forests with different damaged levels (light, moderate, and heavy) in Wuyi Mountains as test sites, this paper studied the effects of this snow storm on the microbial biomass nitrogen and total dissolved nitrogen in 0-10, 10-25, and
25-40 cm soil layers. Except the microbial biomass nitrogen content in 25-40 cm soil layer, the contents of microbial biomass nitrogen and nitrate in the three
soil layers increased with increasing damaged level, and decreased with soil depth. The dissolved organic nitrogen content in 0-10 cm soillayer was significantly higher in heavily damaged bamboo forest than in lightly and moderately damaged bamboo forests. The contents of soil microbial biomass nitrogen, dissolved organic nitrogen, and nitrate in the forests were significantly positively correlated with soil temperature and the ground biomass input caused by the snow storm but negatively correlated with canopy closure, and had no relationship with soil moisture. It was suggested that owing to the changes of biotic and abiotic conditions caused by the snow storm, the soil nitrogen in the forests could be lost from the ecosystem in the forms of nitrate and dissolved organic nitrogen.

Key words: North Hebei plateau, Land-use change, Habitat effect, Land quality, Agriculture-pasture ecotone in north Hebei