Abstract:

In order to study the effects of root exclusion on soil nitrogen mineralization in the forest communities, seasonal variation of the soil NH4+-N, NO3--N and N mineralization were analyzed in Liquidam barformosana and Pinus massoniana communities by using with a PVC tube sequential coring and in-situ incubation method after trenching soils. The results showed NH4+-N, NO3--N and N mineralization in root exclusion treatment was higher than those of the control in two forest communities. The highest net N mineralization rate occurred in summer, the lowest occurred in winter. Contrasted to two forest communities, the net N mineralization rates in Liquidam barformosana was higher than those of Pinus massoniana. NH4+-N, NO3--N and N mineralization were not significantly influenced by root exclusion. However, the N mineralization rate was significantly positively correlated to the soil temperature at 5 cm depth, and was negatively correlated to the soil moisture at 5 cm depth. The results suggested heat and relatively dry were beneficial to the N mineralization.