长期氮沉降对亚热带天然林土壤微生物呼吸及代谢熵的影响

doi:10.13287/j.1001-9332.202608.006

摘要/Abstract

摘要： 本研究依托福建三明森林生态系统国家野外科学观测研究站连续施氮9年的亚热带常绿阔叶林模拟氮沉降实验平台,设置对照(0 kg N·hm^-2·a^-1)、低氮(40 kg N·hm^-2·a^-1)和高氮(80 kg N·hm^-2·a^-1)3个处理,分析表层(0~10 cm)土壤的理化性质、微生物生物量及土壤胞外酶碳(C)、氮(N)、磷(P)化学计量特征,并通过室内培养试验测定了土壤微生物呼吸,以探究长期氮沉降对亚热带森林土壤微生物呼吸及代谢熵(qCO₂)的影响。结果表明:与对照相比,高氮处理使土壤C/N显著降低18.8%,土壤N/P显著提高52.9%,低氮和高氮处理分别使可溶性有机C/N显著降低31.8%和34.6%,使微生物N/P失衡提高了72.8%和29.8%。低氮处理的微生物呼吸显著高于高氮处理,二者均与对照无显著差异;低氮和高氮处理的qCO₂分别较对照显著提高36.8%和21.1%,且低氮处理显著高于高氮处理。逐步回归分析表明,土壤C/N和微生物N/P失衡分别是微生物呼吸和qCO₂变异的主要影响因子,解释度分别为56.2%和58.4%。综上,长期氮沉降对亚热带森林土壤微生物呼吸及代谢熵的影响呈剂量依赖性,即高氮沉降通过降低土壤C/N抑制微生物呼吸,而低氮沉降通过加剧微生物N/P失衡提高微生物代谢熵。

关键词: 代谢熵, 氮沉降, 化学计量特征, 酶活性, 微生物群落结构, 异养呼吸

Abstract: Based on a 9-year nitrogen (N) addition experiment in a subtropical evergreen broad-leaved forest at the Fujian Sanming Forest Ecosystem National Field Observation and Research Station, we examined the effects of long-term N addition on soil microbial respiration and metabolic quotient (qCO₂). We collected surface soils (0-10 cm) from control (CK, 0 kg N·hm^-2·a^-1), low nitrogen (LN, 40 kg N·hm^-2·a^-1), and high nitrogen (HN, 80 kg N·hm^-2·a^-1) treatments, analyzed soil physicochemical properties, microbial biomass, and the stoichiometric characteristics of extracellular enzymes related to carbon (C), N, and phosphorus (P), and measured the soil microbial respiration through laboratory incubation experiments. The results showed that the HN treatment significantly decreased the soil C/N by 18.8% and increased the soil N/P by 52.9%. The LN and HN treatments significantly decreased the dissolved organic C/N by 31.8% and 34.6%, and increased the microbial N/P by 72.8% and 29.8%, respectively. Microbial respiration in the LN treatment was significantly higher than that in the HN treatment, with no differences observed between either treatment and CK. The qCO₂ in the LN and HN treatments was significantly increased by 36.8% and 21.1%, respectively, and the qCO₂ in the LN treatment was significantly higher than that in the HN treatment. Stepwise regression analysis indicated that soil C/N and microbial N/P were the primary factors influencing the microbial respiration and qCO₂, accounting for 56.2% and 58.4% of the variance, respectively. In conclusion, the effects of long-term N deposition on soil microbial respiration and metabolic quotient in subtropical forests were dose-dependent. High N deposition suppressed microbial respiration by reducing soil C/N, whereas low N deposition increased microbial metabolic quotient by exacerbating microbial N/P imbalance.

Key words: metabolic quotient, nitrogen deposition, stoichiometric characteristics, enzyme activity, microbial community structure, heterotrophic respiration

胡晓蝶, 王小红, 高红, 张伟, 黄冰彬, 姚晓东, 陈光水. 长期氮沉降对亚热带天然林土壤微生物呼吸及代谢熵的影响[J]. 应用生态学报, 2026, 37(8): 2537-2546.

HU Xiaodie, WANG Xiaohong, GAO Hong, ZHANG Wei, HUANG Bingbin, YAO Xiaodong, CHEN Guangshui. Effects of long-term nitrogen deposition on soil microbial respiration and metabolic quotient in subtropical natural forests[J]. Chinese Journal of Applied Ecology, 2026, 37(8): 2537-2546.

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