关键词: 麻栎天然林, 土壤呼吸, 土壤温度, 土壤含水率, Q_10, 氮沉降

Abstract: In recent years, emissions of nitrogenous compounds have increased rapidly, which would continue with population growth and urbanization. Such nitrogen falls into forest ecosystems in the form of deposition, with profound impacts on forest soil carbon fluxes. Nitrogen deposition becomes an important factor affecting forest soil respiration. In this study, a nitrogen deposition simulation experiment was carried out in a Quercus acutissima natural forest in Wanfo Mountain, Anhui Province to explore the shortterm impacts of nitrogen addition on soil respiration and components and their sensitivity to temperature and humidity. The soil respiration rate, soil temperature and moisture were measured by LI-8100. Soil respiration and its components had obvious seasonal variations under all the treatments of N0 (control), N1 (low N) and N2 (high N). Both N1 and N2 treatments slightly increased total soil respiration and its components, but without statistical significance (P<0.05). The average annual total soil respiration rates of N0, N1, and N2 treatments were 2.03, 2.17 and 2.13 μmol·m^-2·s^-1, with 6.90% and 4.93% higher in N1 and N2 treatments than in N0 treatment, respectively. There was a significant exponential relationship between soil respiration and soil temperature (P<0.001). The Q₁₀ values of the total soil respiration under N0, N1 and N2 treatments were 2.04, 1.99 and 2.10, respectively. N1 treatment increased the Q₁₀ of the autotrophic respiration but decreased the Q₁₀ of the heterotrophic respiration. N2 treatment increased the Q_10 of each component of soil respiration. There was a significant correlation between soil moisture and soil respiration (P<0.05), with the R² value of its correlation being smaller than that between soil temperature and soil respiration. The composite model of soil respiration with soil temperature and soil moisture performed better than the singlefactor models. Our findings provide a new way to predict the changes of soil respiration and its components under the increasing nitrogen deposition scenarios.

Key words: Quercus acutissima natural forest, soil respiration, soil temperature, soil moisture content, Q₁₀, N deposition.