Abstract: In order to understand the effects of N and P addition on soil available nitrogen and pH in a subtropical evergreen broadleaved forest dominated by Schima superba, we investigated contents of soil NH₄⁺-N, NO₃^--N and pH. Four N and P addition treatments were included as follows: CK (no addition of N and P), N (50 kg N·hm^-2·a^-1), P (15 kg P·hm^-2·a^-1) and NP (100 kg N·hm^-2·a^-1+15 kg P·hm^-2·a^-1). The results showed that: 1) The soil NH₄⁺-N and NO₃^--N concentrations were significantly increased after N addition, and the range of stimulation increased with prolonged nitrogen fertilization time. The soil NO₃^--N concentration was significantly decreased by P addition, and there was no significant impact on soil NH₄⁺-N concentration under P addition. NP addition significantly increased the soil NO₃^--N concentration, and N addition alone had more obvious effects on the soil NO₃^--N concentration than NP addition. The response of soil NH₄⁺-N concentration to NP addition turned from insignificant to significant over time. 2) The soil pH decreased obviously with prolonged N addition and NP addition time, while remained stable under P addition. 3) Relative to the increase of nitrate nitrogen concentration, the same increase of soil ammonium nitrogen concentration resulted in a greater decline in pH value.

Key words: bacterial community, Lefse analysis., high-throughput sequencing, nitrogen deposition