模拟酸雨对土壤呼吸影响的研究进展

土壤呼吸是陆地生态系统与大气环境之间进行碳交换的主要途径,在全球碳循环和碳平衡中占有极其重要的地位。全球变化背景下,由于人类活动而导致日益严重的酸雨问题,其对土壤呼吸的影响越来越受到国内外学者的广泛关注。酸雨导致土壤酸化,对土壤微生物代谢活动、植物地上地下生长以及凋落物分解等产生影响,进而影响土壤呼吸。该文综述了模拟酸雨对森林生态系统和农田生态系统土壤呼吸影响的三种结果,即抑制、促进和无影响;酸雨影响土壤呼吸的差异受到酸雨酸性、酸雨处理持续时间以及植被类型、植物生长季节、植被演替阶段以及土壤理化性质等生物和非生物因素的综合影响。低强度和高强度酸雨都倾向于降低土壤呼吸的温度敏感性(Q_(10))。从影响土壤呼吸的四个关键的生物因子,即光合作用、凋落物、微生物、根系生物量,分析了模拟酸雨影响土壤呼吸的潜在机制;但是酸雨影响土壤呼吸的过程复杂,使得土壤呼吸对酸雨的部分响应机理仍存在不确定性。在此基础上总结了现有研究存在的不足,提出了今后需要给予重点关注的四个方面的研究:(1)不同类型生态系统对酸雨响应的研究;(2)土壤各组分呼吸对酸雨响应的研究;(3)模拟酸雨与其他外界因素的共同作用研究;(4)与土壤呼吸相关的生物因子对酸雨响应的研究。

A review of the effects of simulated acid rain on soil respiration

Soil respiration is a major exchange channel of carbon between terrestrial ecosystem and atmospheric environment; it plays a vitally important role in global carbon cycle and carbon balance. Under the background of global change, the issue of acid rain caused by anthropogenic activities has been serious increasingly; and the effects of increased acid rain on soil respiration have attracted increasing attention all over the world in recent years. Acid rain leads to soil acidification, and it then affects the metabolic activity of soil microbes, root growth, and litter decomposition, etc.; which finally affects soil respiration. This paper reviews the progresses of studies on the effects of simulated acid rain on soil respiration in forest and cropland ecosystem,and there are three kinds of results for the effects: depression, promotion, and no effect. The different results are affected by experimental, biological and non-biological factors, including the experimental acidity and duration of simulated acid rain, vegetation type, plant growth season, vegetation succession phases, and physical and chemical properties of soil, etc. Both the low and high intensity of acid rain tends to reduce the temperature sensitivity(Q₁₀)of soil respiration. This paper also analyzes the potential mechanisms of how acid rain affects the soil respiration in ecosystem from four key biological factors affecting soil respiration, including photosynthesis, litter, microbes and root biomass. However, the process of the effects of acid rain on soil respiration is complex, leading to some uncertainties of the response mechanism of soil respiration to acid rain. Accordingly, some deficiencies for the current studies are summarized, and then four directions are proposed to be considered in the future study:(1)The studies on the responses of soil respiration to acid rain in different ecosystems;(2)The studies on the responses of different components of soil respiration to acid rain;(3)The studies on the combined effects of acid rain and other external factors;(4)The studies on the responses of biological factors that are relevant to soil respiration to acid rain.