The Nitrogen Mineralization of Five Forest Types Soil in Eastern Slope of Gaoligongshan Mountains

Sequential soil coring and in situ exposure of largely undisturbed soil columns technique was used to study the nitrogen mineralization of five forest types soils in the east side of Gaoligongshan mountains, which were Dry-Hot Vally (D), Montane Rain Forest (MR), Monsoon Evergreen Broad-leaved Forest (M), the Mid-Montane Humid Evergreen Broad-leaved Forest (H), Tsuga Forest (Ts). The results indicated that NH4+-N content decreased for all the forest types soil after four months training, the order of decrease proportion is monsoon evergreen broad-leaved forest (84.1%)> montane rain forest (69.3%)> the mid-montane humid evergreen broad-leaved forest (34.7%)> dry-hot vally (8.7%)> tsuga forest (7.3%). And NO3--N content increased for the soils, the increasing multiples is tsuga forest (39.0 times)> dry-hot vally (18.8 times)> the mid-montane humid evergreen broad-leaved forest (4.7 times)> monsoon evergreen broadleaf forest (4.0 times) > montane rainforest (2.8 times). We conclude that NH4+-N is the main form of inorganic nitrogen in forest soil, which is the main reason of changing the soil nitrogen mineralization and mineralization rate.