【目的】探究氮沉降下滇中高原地带性森林土壤特性的改变对土壤呼吸的影响,阐明滇中高原地带性森林土壤呼吸对氮沉降的响应机制,为准确评估亚热带森林生态系统碳含量收支及物质循环提供理论依据。【方法】以滇中高原常绿阔叶林和高山栎林两种地带性森林土壤为研究对象,设置4个氮处理梯度:对照[施氮量0 g/(m²·a),CK]、低氮[施氮量10 g/(m²·a),LN]、中氮[施氮量20 g/(m²·a),MN]和高氮[施氮量25 g/(m²·a),HN],研究施氮后土壤呼吸(RS)、温度(T)、湿度(W)和有机碳(TOC)、全氮(TN)、全磷(TP)、硝态氮($\mathrm{NO}_{3}^{-}-\mathrm{N}$)、铵态氮($\mathrm{NH}_{4}^{+}-\mathrm{N}$)含量及微生物生物量碳、氮(MBC、MBN)的动态变化特征,分析氮沉降对土壤呼吸的影响。【结果】①与CK处理相比,常绿阔叶林土壤呼吸在LN处理下增加,在MN、HN处理下降低;高山栎林土壤呼吸随施氮量增加而增大。②旱季时两种林分土壤呼吸低于雨季,雨季较旱季分别增长了155.15%(高山栎林)和181.78%(常绿阔叶林)。③不同季节两种林分土壤TOC、TN、$\mathrm{NO}_{3}^{-}-\mathrm{N}$、$\mathrm{NH}_{4}^{+}-\mathrm{N}$含量均随施氮量增加而增加,雨季时两种林分土壤MBC在各施氮处理下均低于CK。④旱季和雨季常绿阔叶林土壤呼吸与pH、TP含量、MBN存在一定的正相关(P>0.05不显著,下同);高山栎林土壤呼吸与TOC、TN、$\mathrm{NO}_{3}^{-}-\mathrm{N}$ 和$\mathrm{NH}_{4}^{+}-\mathrm{N}$含量存在一定正相关关系(P>0.05),与TP含量、MBC和MBN呈现一定的负相关关系(P>0.05),并与pH显著负相关(P<0.05)。【结论】氮沉降可通过影响土壤TOC、TN、TP、$\mathrm{NO}_{3}^{-}-\mathrm{N}$、$\mathrm{NH}_{4}^{+}-\mathrm{N}$含量及MBC和MBN使土壤呼吸发生改变,适量的氮沉降对土壤呼吸具有促进作用,过量的氮添加会抑制土壤呼吸。

【Objective】The study explored effects of changes in soil characteristics in zonal forests on soil respiration under nitrogen deposition in the central Yunnan Plateau. The study aimed to elucidate the mechanism underlying the response of soil respiration to nitrogen deposition in zonal forests, and provide a theoretical basis for the accurate assessment of the carbon budget and material cycle of subtropical forest ecosystems. 【Method】This study focused on two types of zonal forest soils, namely, evergreen broad-leaved forests and Quercus aquifolioides forests, in the central Yunnan Plateau. The soils were treated with different gradients of nitrogen, control [0 g/(m²·a) nitrogen, CK], low nitrogen [10 g/(m²·a) nitrogen, LN], medium nitrogen [20 g/(m²·a) nitrogen, MN], and high nitrogen [25 g/(m²·a) nitrogen, HN]. The variations in the characteristics of soil respiration (RS), temperature (T), humidity (W), organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), nitrate nitrogen ($\mathrm{NO}_{3}^{-}-\mathrm{N}$), ammonium nitrogen ($\mathrm{NH}_{4}^{+}-\mathrm{N}$) content, microbial biomass carbon (MBC), and microbial biomass nitrogen (MBN) were determined under nitrogen deposition. Additionally, the correlation between soil respiration and soil characteristics were determined to elucidate the mechanism underlying the effect of nitrogen deposition on soil respiration. 【Result】Compared to the CK group, soil respiration increased in the LN treatment group and decreased in the MN and HN treatment groups in the evergreen broad-leaf forests. Compared with the CK group, soil respiration increased with an increase in nitrogen application for all the treatment groups in the Q. aquifolioides forests. Soil respiration was lower in the dry season than that in the rainy season in both stands, and increased by 155.15% and 181.78% in the Q. aquifolioides and evergreen broad-leaf forests, respectively, in the rainy season compared to those in the dry season. The TOC, TN, $\mathrm{NO}_{3}^{-}-\mathrm{N}$, and $\mathrm{NH}_{4}^{+}-\mathrm{N}$ contents in the soil increased with the gradient of applied nitrogen in different seasons in both stands. Additionally, the contents of soil MBC in both stands were lower than that of the CK group in the rainy season at the different concentrations of nitrogen. The soil respiration of the evergreen broad-leaved forests exhibited a non-significant positive correlation with the pH, TP content and MBN (P > 0.05) in the dry and rainy seasons. Soil respiration in the Q. aquifolioides forests exhibited a non-significant positive correlation with the TOC, TN, $\mathrm{NO}_{3}^{-}-\mathrm{N}$, and $\mathrm{NH}_{4}^{+}-\mathrm{N}$ content, non-significant negative correlation with the TP content, MBC and MBN, and a significant negative correlation with the pH (P < 0.05) during the dry and rainy seasons. 【Conclusion】Nitrogen deposition can alter soil respiration by affecting the soil chemical indicators, including the TOC, TN, TP, $\mathrm{NO}_{3}^{-}-\mathrm{N}$, $\mathrm{NH}_{4}^{+}-\mathrm{N}$ content, MBC, and MBN. The findings revealed that moderate nitrogen deposition can promote soil respiration, while excessive nitrogen addition can inhibit soil respiration.