中文关键词模拟酸雨土壤呼吸异养呼吸Q₁₀(温度敏感性)碳氮比pH 英文关键词simulated acid rainsoil respirationheterotrophic respirationQ₁₀(temperature sensitivity)soil carbon-nitrogen ratiopH

作者	单位	E-mail
李一凡	北京林业大学水土保持学院, 重庆缙云山三峡库区森林生态系统国家定位观测研究站, 北京 100083 北京市水土保持工程技术研究中心, 北京 100083	yfan20151003@163.com
王玉杰	北京林业大学水土保持学院, 重庆缙云山三峡库区森林生态系统国家定位观测研究站, 北京 100083 北京市水土保持工程技术研究中心, 北京 100083	wyujie@bjfu.edu.cn
王彬	北京林业大学水土保持学院, 重庆缙云山三峡库区森林生态系统国家定位观测研究站, 北京 100083 北京市水土保持工程技术研究中心, 北京 100083
王云琦	北京林业大学水土保持学院, 重庆缙云山三峡库区森林生态系统国家定位观测研究站, 北京 100083 北京市水土保持工程技术研究中心, 北京 100083

中文摘要 为研究酸雨对森林土壤呼吸的影响，于2016年1月~2017年4月在重庆缙云山三峡库区针阔混交林内选取3块样地，设置了断根与不断根两组处理，每组处理设置pH为4.5（对照）、4.0、3.25和2.5共4个梯度的模拟酸雨处理.试验观测模拟酸雨下土壤总呼吸与异养呼吸变化特征及土壤温度、土壤湿度，同时采集土样，研究土壤pH、碳氮比及细根生物量对土壤呼吸的影响.结果表明，土壤总呼吸与异养呼吸均表现出了季节变异趋势.不断根样方的CK、T4.0、T3.25和T2.5处理的年均土壤呼吸速率分别为1.89、1.88、1.75和1.74μmol·（m²·s）^-1，断根样方的RCCK、RCT4.0、RCT3.25和RCT2.5处理的年均土壤呼吸速率分别为1.37、1.32、1.19和1.08μmol·（m²·s）^-1.季度平均土壤总呼吸与异养呼吸在2016年7月前差异不显著（P>0.05），2016年10月后差异均显著（P<0.01）并呈现对照 > pH4.0 > pH3.25 > pH2.5.2016年的累积土壤呼吸量T4.0、T3.25和T2.5处理相比对照分别降低3.89%、9.64%和11.24%，RCT4.0、RCT3.25和RCT2.5处理相比对照分别降低6.79%、13.23%和25.56%.与对照相比，模拟酸雨处理降低了异养呼吸占比，降低程度随着酸雨pH增加而加强，说明了酸雨对于异养呼吸的抑制超过了自养呼吸.模拟酸雨处理虽然增加了土壤呼吸的温度敏感性，但是对土壤温度与湿度无显著影响（P>0.05）；2016年10月之后相比对照模拟酸雨处理显著增加了土壤碳氮比、降低了细根生物量.土壤呼吸与细根生物量有显著正相关关系，与土壤碳氮比有显著的负相关关系.土壤温度与水分对模拟酸雨下土壤呼吸的差异贡献不大，细根生物量与碳氮比是酸雨处理下呼吸差异的主要影响因素. 英文摘要 In order to study the effects of acid rain on forest soil respiration, three plots were selected in the conifer/broad-leaved mixed forests in the Three Gorges Reservoir area of the Jinyun Mountain (Chongqing) from January 2016 to April 2017. Two groups of treatments were set up:a trenched treatment and an untrenched treatment. Each group was treated with four simulated acid rain gradients of pH 4.5 (control), 4.0, 3.25 and 2.5. The characteristics of total soil respiration and heterotrophic respiration under the four simulated acid rain treatments were measured. Soil temperature and moisture were measured during the respiration measurements, and soil samples were collected to study the effects of soil pH, the carbon-nitrogen ratio, and fine root biomass on soil respiration. The results indicated that the total soil respiration and heterotrophic respiration of trenched and untrenched plots showed a similar seasonal variation trend. The annual mean soil respiration rates of the CK, T4.0, T3.25, and T2.5 treatments were 1.89, 1.88, 1.75, and 1.74 μmol·(m²·s¹)^-1, respectively, and the annual mean soil respiration rates of the RCCK, RCT4.0, RCT3.25 and RCT2.5 treatments were 1.37, 1.32, 1.19, 1.08 μmol·(m²·s¹)^-1, respectively. There was no significant differences between the quarterly average of the total soil respiration and heterotrophic respiration before June 2016 (P>0.05). However, after October 2016, the difference was significant (P<0.01) with CK > pH 4.0 > pH 3.25 > pH 2.5. The cumulative soil CO₂ emissions of the T4.0, T3.25, and T2.5 treatments in 2016 decreased by 3.89%, 9.64%, and 11.24% respectively, compared with the control, and the RCT4.0, RCT3.25, and RCT2.5 treatments decreased by 6.79%, 13.23%, and 25.56%, respectively. The simulated acid rain treatments reduced the ratio of heterotrophic respiration in the total soil respiration, and the degree of reduction increased with the pH of the simulated acid rain, indicating that the effect of acid rain on the inhibition of heterotrophic respiration exceeded that of autotrophic respiration. Although the simulated acid rain treatments increased the temperature sensitivity of soil respiration (Q₁₀), it had no significant effect on soil temperature and humidity (P>0.05). The soil carbon-nitrogen ratio and fine root biomass were significantly greater in comparison to the control after October 2016. Soil respiration was significantly positively correlated with fine root biomass and significantly negatively correlated with the soil carbon-nitrogen ratio. Soil temperature and water contributed only slightly to soil respiration under the four simulated acid rain treatments. Fine root biomass and the soil carbon-nitrogen ratio were critical factors for variation of soil respiration under acid rain.

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