模拟酸沉降对南亚热带季风常绿阔叶林土壤微生物群落结构的长期影响

土壤微生物是生态系统重要的组成成分, 尤其是在土壤风化严重, 养分贫瘠的热带和南亚热带森林生态系统中, 微生物在植物养分的获取、碳循环以及土壤的形成等生态过程中的作用尤为重要。该研究基于鼎湖山南亚热带季风常绿阔叶林长期(10年)的野外模拟酸沉降实验平台, 探究了土壤微生物群落结构对土壤酸化的响应。结果表明, 酸沉降处理显著降低土壤pH (即加剧酸化)。土壤酸化对微生物生物量碳(C)含量的影响不大, 但改变了土壤微生物生物量氮(N)和磷(P)的含量, 导致表层土壤(0-10 cm)微生物生物量C:P和N:P显著提高, 表明土壤酸化可能加剧了微生物P限制。土壤酸化还显著改变了土壤微生物群落结构, 导致次表层土壤(10-20 cm)真菌:细菌显著增加。进一步分析表明, 土壤pH和土壤有效P含量是影响土壤微生物群落最为主要的两个因素。

Effects of long-term simulated acid rain on soil microbial community structure in a monsoon evergreen broad-leaved forest in southern China

Aims Soil microorganisms are an important component of terrestrial ecosystems and play a critical role in regulating multiple ecological processes such as nutrient acquisition, carbon cycle, and soil formation, especially in the tropical forests where soils are highly weathered with poor nutrients. The objective of this study was to examine the response of soil microbial community under long-term simulated acid rain (SAR) and investigate the most important factors influencing microbial community structure.Methods Based on a long-term (10-year) field SAR experiment, we investigate the response of soil microbial community structure to soil acidification in the south subtropical monsoon evergreen broad-leaved forest of Dinghushan National Nature Reserve. Four levels of SAR treatments were set by adding the following amount of H⁺: 0 (CK), 9.6, 32 and 96 mol·hm^-2·a^-1.Important findings 1) The SAR treatment significantly reduced the pH value of soil (i.e., increased soil acidification). 2) Soil acidification did not significantly influence microbial carbon (C) content, but changed microbial nitrogen (N) and phosphorus (P) contents, leading to significant increases in microbial C:P and N:P in topsoil (0-10 cm). This result indicated that soil acidification might aggravate microbial P limitation. 3) Soil acidification also altered the microbial community structure and significantly increased the fungal/bacterial ratio in the subsoil (10-20 cm). Further analysis showed that soil pH and available P content were the most important factors affecting the soil microbial communities under the SAR treatment.