Mycorrhizal fungi alleviate acidification‐induced phosphorus limitation: Evidence from a decade‐long field experiment of simulated acid deposition in a tropical forest in south China

• Published in: Global change biology 2022-06, Vol.28 (11), p.3605-3619
• Main Authors: Hu, Yuanliu, Chen, Ji, Hui, Dafeng, Wang, Ying‐Ping, Li, Jianling, Chen, Jingwen, Chen, Guoyin, Zhu, Yiren, Zhang, Leiyi, Zhang, Deqiang, Deng, Qi
• Format: Article
• Language: English
• Subjects: Acid deposition; Acidic soils; Acidification; Acids; Aluminum; Arbuscular mycorrhizas; China; Deposition; Dry season; Ecosystem; Ectomycorrhizas; Forests; Fractions; Fungi; geochemical processes; Hydrogen-Ion Concentration; Iron; Microorganisms; Mycorrhizae - physiology; mycorrhizal fungi; Nitrogen - pharmacology; Oxides; Oxisol; phosphatase; Phosphoric Monoester Hydrolases; Phosphorus; Phosphorus - analysis; phosphorus fractions; Pollutant deposition; Pools; Rainy season; Seasonal variation; Seasonal variations; Seasons; Soil; Soil acidification; Soil Microbiology; Soils; Tropical climate; tropical forest; Tropical forests; Wet season
• ISSN: 1354-1013; 1365-2486
• DOI: 10.1111/gcb.16135

South China has been experiencing very high rate of acid deposition and severe soil acidification in recent decades, which has been proposed to exacerbate the regional ecosystem phosphorus (P) limitation. We conducted a 10‐year field experiment of simulated acid deposition to examine how acidification impacts seasonal changes of different soil P fractions in a tropical forest with highly acidic soils in south China. As expected, acid addition significantly increased occluded P pool but reduced the other more labile P pools in the dry season. In the wet season, however, acid addition did not change microbial P, soluble P and labile organic P pools. Acid addition significantly increased exchangeable Al3+ and Fe3+ and the activation of Fe oxides in both seasons. Different from the decline of microbial abundance in the dry season, acid addition increased ectomycorrhizal fungi and its ratio to arbuscular mycorrhiza fungi in the wet season, which significantly stimulated phosphomonoesterase activities and likely promoted the dissolution of occluded P. Our results suggest that, even in already highly acidic soils, the acidification‐induced P limitation could be alleviated by stimulating ectomycorrhizal fungi and phosphomonoesterase activities. The differential responses and microbial controls of seasonal soil P transformation revealed here should be implemented into ecosystem biogeochemical model for predicting plant productivity under future acid deposition scenarios. A conceptual framework of acidification impacts on soil phosphorus (P) transformation. Soil acidification enhanced exchangeable Al3+ and Fe3+ and the activation of Fe oxides in both season, which significantly elevated occluded P pool but lowered the other P fraction pools in the dry season. However, soil P availability in the wet season remained constant likely due to the increased ECM that promoted the dissolution of occluded P into the labile Po, followed by the stimulated phosphomonoesterase activities that convert the hydrolysable Po forms into soluble P. Notes: The black solid line shows the conversion between P factions. The dashed arrows with red or blue indicate how geochemical and microbial processes positively or negatively regulate soil P transformation, respectively. The upward red arrow indicates an increasing trend. The blue down arrow indicates a downswing trend. MBP: soil microbial biomass phosphorus; Pi: inorganic P; Po: organic P; F/B: the ratio of fungi to bacteria; ECM: ectomyc