The effects of grassland degradation and temperature changes on soil organic phosphorus mineralization characteristics and temperature sensitivity in alpine regions

Grassland degradation is one of the major environmental issues threatening alpine ecosystems globally, profoundly affecting soil nutrient cycling and ecological functions. This study investigated the impacts of grassland degradation and temperature gradients (5°C, 10°C, 15°C) on soil organic phosphorus (P) mineralization characteristics and temperature sensitivity through an isothermal and moisture-controlled incubation experiment. The study was conducted in the Zoige Plateau, focusing on non-degraded meadows (ND), lightly degraded meadows (LD), moderately degraded meadows (MD), and heavily degraded meadows (HD). The results showed that the soil organic P mineralization rate and potential varied significantly over incubation time across different degradation levels, with interactive effects of degradation and temperature playing a critical role in the mineralization process. At high temperatures (≥15°C), grassland degradation significantly reduced net mineralization rates and mineralization potential, with MD and HD soils exhibiting a 55.8% and 57.2% reduction in net mineralization rates and a 29.5% and 40.4% decrease in mineralization potential (B₀ values) compared to ND soils, respectively. Additionally, the temperature sensitivity coefficient (Q₁₀) of soil organic P mineralization decreased with increasing degradation levels, with ND soils showing significantly higher Q₁₀ values than degraded soils, indicating that grassland degradation weakened the soil’s response to temperature changes. This study highlights the negative effects of grassland degradation on soil organic P mineralization and its temperature sensitivity, emphasizing that temperature is a crucial driver regulating soil organic P mineralization. Furthermore, it discusses the potential risks of exacerbated phosphorus cycle imbalances under global warming scenarios due to grassland degradation. The findings provide a scientific basis for ecological restoration and soil phosphorus management in alpine grasslands, contributing to the sustainable development of grassland ecosystems under climate change.