酸雨对土壤呼吸的影响机制研究进展与展望

土壤呼吸是陆地生态系统与大气之间进行碳交换的主要途径,其动态变化直接影响着全球碳平衡。由于人类活动的影响,酸雨成为人类当前面临的最严重的生态环境问题之一,但其对土壤呼吸的影响及其机理尚无定论。本文综述了不同生态系统土壤呼吸对酸雨的响应特征,多数文献表明,高强度的酸雨抑制土壤呼吸,而在低强度的酸雨作用下土壤呼吸的响应存在差异。从影响土壤呼吸的4个关键生物因子,即光合作用、微生物、凋落物和根系生物量,重点讨论了酸雨对土壤呼吸的影响机制。在此基础上,提出了以下研究展望:①开展土壤呼吸对不同组成类型酸雨的响应研究;②开展与土壤碳排放相关的功能微生物对酸雨的响应研究;③开展不同物候期土壤呼吸对酸雨的响应研究;④开展土壤呼吸各过程对酸雨的响应研究;⑤建立全球酸雨地区土壤碳排放监测研究网络。

Effects of Acid Rain on Soil Respiration and Underlying Mechanisms: A Review

Soil respiration is the greatest carbon fluxes from terrestrial ecosystem to the atmosphere, and therefore any tiny changes in soil respiration could result in great impact on the global carbon balance. Due to anthropogenic activities, acid rain has been one of the most serious environmental problems, but its impacts on soil respiration and the underlying mechanisms remain inconclusive. This paper reviewed the responses of soil respiration to acid rain in different ecosystems, summarized and discussed the underlying mechanisms by which acid rain changes soil respiration. Results showed that strong acid rain suppressed soil respiration, while medium and low acids did not alter soil respiration consistently across studies. Four important biological factors including photosynthesis process, microbial communities, litter decomposition and root-productivity were discussed in details. Moreover, further studies in regard to acid rain effects on soil respiration could highlight in these aspects as listed below: 1) how different types of acid rain would affect soil respiration; 2) how acid rain would affect functional microbes and related genes involving the terrestrial C cycling; 3) whether soil respiration at different plant phonological stages would respond similarly to acid rain; 4) how different soil respiration components and related processes (e.g., autotrophic and heterotrophic soil respiration) would respond differently to acid rain; and 5) a global monitoring network should be established to further understand effects of acid rain on soil respiration across climatic zones and ecosystems in the acid rain affected areas.