Abstract:We studied the contents of inorganic nitrogen in surface and subsurface soil within six different vegetation types at Fushi Reservoir watershed in Anji County of northern Zhejiang Province, and the influence of different vegetation types on soil inorganic nitrogen distribution. There is significant difference(P＜0.05) between the contents of soil NO-3-N and NH+4-N at Tianjia mountain and Rihui mountain watershed, and the maximum differences of soil NO-3-N and NH+4-N are 10.09 and 11.45 mg·kg-1 in plant non-growing season with more drastic fluctuations when compared to the plant growing season(9.6 and 2.72 mg·kg-1). Soil organic nitrogen accounts for more than 97.0% of the total nitrogen at six vegetation types in two seasons. By the correlation analysis, there is a close relationship between NO-3-N and NH+4-N of 0-20 cm soil with the physical and chemical properties of soil itself for six vegetation types. The total nitrogen input to reservoir in the plant nongrowing season is higher than that in the growing season, and that of Rihui mountain watershed is significantly greater than that of Tianjia mountain watershed, 1.49 times and 1.55 times more than that of Tianjia mountain watershed in two plant seasons, respectively. The plant non-growing season shows a greater risk of nitrogen loss in this region, and it is also the key stage for the nitrogen pollution control, Metasequoia glyptostroboides forest and Echinochloa crusgalli(L.) Beauv show a larger capacity for storing and retaining nitrogen, which are suitable for large-scale construction to protect the water quality of Fushi Reservoir watershed.