Abstract: An in situ field experiment was conducted to study the effects of simulated nitrogen (N) deposition on soil acid phosphomonoesterase activity (APA) an
d soil available phosphorous (AP) content in Pinus massoniana forest (PF), coniferous and broad-leaved mixed forest (MF), and monsoon evergreen broad-leaved forest (MEBF) in Dinghushan Mountain. In PF and MF, three treatments were installed, i.e., CK (0 kg N·hm^-2·a^-1), low N (50 kg N·hm^-2·a^-1), and medium N (100 kg N·hm^-2·a^-1); in MEBF, four treatments were installed, i.e., CK, low N, medium N, and high N (150 kg N·hm^-2·a^-1). The soil APA and soil AP content decreased with soil depth. The soil APA was the highest in MEBF, while the AP content had no significant difference in the three forests. The effects of N addition on soil APA differed with forest types. In MEBF, the APA was the highest (19.52 μmol·g^-1·h^-1) in low N treatment; while in PF and MF, the APA was the highest (12.74 and 11.02 μmol·g^-1·h^-1, respectively) in medium N treatment. In the three forests, soil AP content was the highest in low N treatment, but had no significant differences among the N treatments. There was a significant positive correlation between soil APA and soil AP content.

Key words: acid phosphomonoesterase activity, available phosphorous, nitrogen de position, Dinghushan Mountain