Wei Hui, Liu Wen, Zhang Jiaen, Qin Zhong
Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China; Key Laboratory of Tropical Agro-Environment, Ministry of Agriculture, South China Agricultural University, Guangzhou 510642, China; Guangdong Engineering Research Center for Modern Eco-agriculture and Circular Agriculture, Guangzhou 510642, China.
Department of Ecology, College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
Environ Pollut. 2017 Jan;220(Pt A):460-468. doi: 10.1016/j.envpol.2016.09.088. Epub 2016 Sep 30.
Acid rain is one of the severest environmental issues globally. Relative to other global changes (e.g., warming, elevated atmospheric [CO], and nitrogen deposition), however, acid rain has received less attention than its due. Soil fauna play important roles in multiple ecological processes, but how soil fauna community responds to acid rain remains less studied. This microcosm experiment was conducted using latosol with simulated acid rain (SAR) manipulations to observe potential changes in soil fauna community under acid rain stress. Four pH levels, i.e., pH 2.5, 3.5, 4.5, and 5.5, and a neutral control of pH 7.0 were set according to the current pH condition and acidification trend of precipitation in southern China. As expected, we observed that the SAR treatments induced changes in soil fauna community composition and their ecological niches in the tested soil; the treatment effects tended to increase as acidity increased. This could be attributable to the environmental stresses (such as acidity, porosity and oxygen supply) induced by the SAR treatments. In addition to direct acidity effect, we propose that potential changes in permeability and movability of water and oxygen in soils induced by acid rain could also give rise to the observed shifts in soil fauna community composition. These are most likely indirect pathways of acid rain to affect belowground community. Moreover, we found that nematodes, the dominating soil fauna group in this study, moved downwards to mitigate the stress of acid rain. This is probably detrimental to soil fauna in the long term, due to the relatively severer soil conditions in the deep than surface soil layer. Our results suggest that acid rain could change soil fauna community and the vertical distribution of soil fauna groups, consequently changing the underground ecosystem functions such as organic matter decomposition and greenhouse gas emissions.
酸雨是全球最严重的环境问题之一。然而，相对于其他全球变化（如气候变暖、大气中二氧化碳浓度升高和氮沉降），酸雨受到的关注与其应得的关注程度相比要少。土壤动物在多个生态过程中发挥着重要作用，但土壤动物群落如何响应酸雨的研究仍较少。本微观实验使用红壤并进行模拟酸雨（SAR）处理，以观察酸雨胁迫下土壤动物群落的潜在变化。根据中国南方当前的降水pH条件和酸化趋势，设置了四个pH水平，即pH 2.5、3.5、4.5和5.5，以及一个pH 7.0的中性对照。正如预期的那样，我们观察到SAR处理导致了受试土壤中土壤动物群落组成及其生态位的变化；随着酸度增加，处理效果趋于增强。这可能归因于SAR处理引起的环境胁迫（如酸度、孔隙度和氧气供应）。除了直接的酸度效应外，我们认为酸雨引起的土壤中水分和氧气渗透性及流动性的潜在变化也可能导致观察到的土壤动物群落组成的变化。这些很可能是酸雨影响地下群落的间接途径。此外，我们发现线虫是本研究中占主导地位的土壤动物类群，它们向下移动以减轻酸雨的压力。从长期来看，这可能对土壤动物不利，因为深层土壤条件比表层土壤相对更恶劣。我们的结果表明，酸雨可能会改变土壤动物群落以及土壤动物类群的垂直分布，从而改变地下生态系统功能，如有机质分解和温室气体排放。
