Reveals divergent phosphorus adaptation strategies of tropical tree-mycorrhizal types after 12 years of simulated acid rain

Acid rain is one of the most serious global environmental problems. Especially in southern China, persistent acid rain has led to severe soil acidification and the depletion of nutrients and base cations, thereby threatening ecosystem structure and function. Previous studies of Qi Deng's lab have shown that soil acidification after decades acid rain accelerated the activation of Fe and Al oxides and their adsorption of phosphorus (P), thereby reducing soil P availability (Hu et al., 2023, Science of the Total Environment). Although plants may alleviate acidification-induced P limitation by stimulating mycorrhizal-mediated organic P mineralization (Hu et al., 2022, Global Change Biology), the responses and underlying mechanisms of these tropical trees under intensified acid rain remain unclear.

Based on a 12-year simulated acid rain experiment in a monsoon evergreen broad-leaved forest at the Dinghushan National Nature Reserve, This examined how tropical trees associated with ectomycorrhizal (ECM) or arbuscular mycorrhizal fungi (AMF) respond to acid rain-induced soil P deficiency, from the perspectives of both soil P acquisition and foliar P utilization. This found that ECM and AMF trees may cope with acid-induced P deficiency by divergent P strategies. Specifically, (1) This did not find significant changes of rhizosphere soil P availability and foliar P content in ECM trees, which were primarily associated with increased soil phosphatase activity and relative abundance of its related genes. (2) Although acid rain significantly reduced rhizosphere soil P availability and foliar P content in AMF trees, This found a stronger reallocation in foliar P fractions than ECM trees, with decreased proportion of structural P but increased metabolic P. These findings suggest that, to cope with acid-induced P limitation, ECM trees tend to adopt an acquisitive nutrient-use strategy for greater P mobilization, while AMF trees favor a conservative strategy with more efficient foliar P utilization.

This study titled 'Tropical tree-mycorrhizal types show divergent phosphorus adaptive strategies after 12-year simulated acid rain' was published online in Soil Biology and Biochemistry. HU Yuanliu, a postdoctoral fellow at South China Botanical Garden, Chinese Academy of Sciences, is the first author of this paper. The corresponding authors is DENGQi, a professor at South China Botanical Garden, Chinese Academy of Sciences. Paper link: https://doi.org/10.1016/j.soilbio.2025.109968

Figure. Differential responses of ectomycorrhizal fungi trees (a) and arbuscular mycorrhizal fungi trees (b) to simulated acid rain treatments. (image by HU et al)