Abstract: From December 2007 to November 2008, an in situ experiment was conducted to study the effects of simulated nitrogen deposition on the soil respiration in a Neosinocalamus affinis plantation in Rainy Area of West China. Four treatments were installed, i.e., 0 (CK), 50, 150, and 300 kg N·hm^-2·a^-1, and soil respiration rate was measured by infrared gas analyzer. In the test plantation, soil respiration rate had a distinct seasonal fluctuation, with the highest (3.36±0.20 μmol·m^-2·s^-1) by the end of July and the lowest by the end of February (0.33±0.07 μmol·m^-2·s^-1). There was a significant exponential relationship (P<0.001) between soil respiration rate and soil temperature, and the temperature at 10 cm soil depth explained 91.6% of the seasonal change of soil respiration. However, less relationship was observed between soil respiration rate and soil moisture content (R²=0.0758). From June to November 2008, the contribution of root respiration to total soil respiration ranged from 46% to 59%. The annual release amount of CO₂ in treatments 50, 150, and 300 kg·hm^-2·a^-1 was 23.6%, 46.7%, and 50.5% lower than that in CK (2.17×10⁴ kg ·hm^-2), and the Q₁₀ value of soil respiration rate in treatments 0, 50, 150, and 300 kg·hm^-2·a^-1 was 3.72, 3.51, 2.95, and 2.71, respectively.

Key words: nitrogen deposition, soil respiration, Neosinocalamus affinis, Rainy Area of West China, plant , heat stress, molecular mechanism, proteomics.