研究了南亚热带主要森林类型 (马尾松林、混交林和季风常绿阔叶林 )土壤有效氮含量对模拟氮沉降的初期响应。结果显示 :(1)马尾松林、混交林和阔叶林 0～ 10 cm和 10～ 2 0 cm两个土层有效氮 (铵态氮 +硝态氮 )含量总平均分别为 6 .2 4、6 .2 2和14 .77m g/kg,其中铵态氮占 4 5 .3%、4 8.7%和 14 .5 %。 (2 )外加氮处理使 3个森林两个土层的有效氮含量都在增加 ,但其影响程度取决于土层、氮处理水平、氮处理时间和森林类型。总体而言 ,0～ 10 cm土层略比 10～ 2 0 cm土层敏感 ;氮处理水平越高土壤有效氮增加越多 ;外加氮处理时间越长 ,处理样方与对照样方的差距越大 ;阔叶林的响应稍落后于马尾松林和混交林 The initial responses of soil available nitrogen to simulated nitrogen deposition in the major subtropical forest types (Pinus massoniana forest, mixed forest and monsoon evergreen broad-leaved forest) were studied. The results showed that: (1) The average contents of available nitrogen (ammonium nitrogen + nitrate nitrogen) in 0-10 cm and 10-20 cm soil mass of Pinus massoniana forest, mixed forest and broadleaved forest were respectively 6.24, 6 .2 2 and 14 .77 m g / kg, with ammonium nitrogen accounting for 45.3%, 48.7% and 14.5%. (2) The content of available nitrogen in the two soil layers increased with the addition of nitrogen, but the degree of influence depends on the soil layer, the level of nitrogen treatment, the time of nitrogen treatment and the type of forest. In general, the 0-10 cm soil layer is slightly more sensitive than the 10-20 cm soil layer. The higher the N treatment level is, the more soil available N increases. The longer the N treatment time is, the greater the difference is Large; broadleaf forest response slightly behind the Pinus massoniana forest and mixed forest