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Alpine meadow degradation decreases soil P availability by altering phoD-harboring bacterial diversity

yanuo zou, Xiangtao Wang, Jie Wang, Lu Zhang, Lirong Liao, Guobin Liu, Zilin Song, Chao Zhang

Abstract

Context: Soil degradation is usually accompanied by significant changes in phosphorus (P) availability, which complicates soil management. However, the effect of ecosystem degradation on soil P availability remains poorly understood, especially in alpine ecosystem, which is one of the most understudied and vulnerable terrestrial habitats of the planet. Aims: Assess the effect of meadow degradation on soil P availability in alpine ecosystem. Methods: Changes in soil P-related properties, phoD-harboring bacterial communities, and alkaline phosphatase levels were investigated in four alpine meadows along a degradation gradient (non-degraded, lightly degraded, moderately degraded, and severely degraded) on the Tibetan Plateau. Key results: We found meadow degradation reduced alkaline phosphatase activity by 6.3–11.22% and soil P availability by 27.1–42.4% compared to the respective values in the non-degraded meadows, but this negative impact was only observed in moderately and severely degraded meadows. Meadow degradation caused a P limitation on the phoD-harboring community and a decline in the abundance of phoD genes and diversity of phoD-harboring bacterial communities, with an increase in oligotrophic groups (e.g., Actinobacteria) and a reduction in copiotrophic groups (e.g., Proteobacteria). The degradation-induced reduction in soil C supply and plant biomass decreased soil P availability by lowering the activity of alkaline phosphatases, which are closely associated with phoD-harboring bacterial structure and diversity. Alloactinosynnema and Actinomadura were identified as the key taxa contributing to alkaline phosphatases activity. Conclusions: Alpine meadow degradation decreases soil P availability by altering phoD-harboring bacterial diversity. Implications: Our results revealed the mechanisms of decreased P availability during alpine meadow degradation, which can guide the restoration of degraded meadow ecosystems.

SR23133  Accepted 18 April 2024

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