Purpose

Grasslands are the most extensive vegetation type in the terrestrial ecosystem and have an important role in the soil phosphorus (P) cycle. Many nutrient addition and warming experiments have been conducted in grasslands; however, the global pattern of nutrient addition and experimental warming impacts on soil P cycle is unclear.

Methods

We conducted a meta-analysis of 68 publications to synthesize the mechanisms underlying global grassland ecosystem responses to nutrient addition and experimental warming.

Results

Our analysis indicated that nitrogen (N) addition reduced microbial biomass P (− 11.2%) but increased litter P concentration (+ 15.5%) and available P (+ 14.2%). Experimental warming reduced microbial biomass P (− 10.5%) and available P (− 6.7%) but increased litter P concentration (+ 46.2%). P addition increased available P (+ 222.3%) and microbial biomass P (+ 98.1%). The available P response to nutrient addition and experimental warming was more sensitive in temperate grasslands than in alpine grasslands. The responses of soil total and available P to nutrient addition depended on environmental conditions such as air temperature and soil pH.

Conclusion

Our results suggest that N addition may promote P mineralization and possibly stimulate the transformation of refractory or resistant forms of soil inorganic P, whereas experimental warming accelerates the P cycle by regulating plant acquisition and enzyme activity. Environmental factors (e.g., temperature, precipitation, pH) affect the soil P response to nutrient addition by altering microbial and enzymatic activities. It is crucial to understand the dynamic changes in soil microbial and enzyme activities to predict the P cycle in grassland soils in the future.

中文翻译：

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养分添加和变暖改变草原土壤磷循环：一项全球荟萃分析

目的

草原是陆地生态系统中最广泛的植被类型，在土壤磷（P）循环中具有重要作用。在草原上进行了许多养分添加和变暖实验；然而，全球养分添加模式和实验变暖对土壤磷循环的影响尚不清楚。

方法

我们对 68 篇出版物进行了荟萃分析，以综合全球草原生态系统对营养添加和实验性变暖的反应机制。

结果

我们的分析表明，氮 (N) 添加减少了微生物生物量 P (- 11.2%)，但增加了凋落物 P 浓度 (+ 15.5%) 和有效 P (+ 14.2%)。实验性变暖降低了微生物生物量 P (- 10.5%) 和有效 P (- 6.7%)，但增加了凋落物 P 浓度 (+ 46.2%)。P 添加增加了有效 P (+ 222.3%) 和微生物生物量 P (+ 98.1%)。温带草原对养分添加和实验性变暖的有效磷响应比高寒草原更敏感。土壤总磷和速效磷对养分添加的响应取决于气温和土壤 pH 值等环境条件。

结论

我们的研究结果表明，N 添加可能促进 P 矿化并可能刺激土壤无机 P 的难降解或抗性形式的转化，而实验性变暖通过调节植物获取和酶活性来加速 P 循环。环境因素（例如，温度、降水、pH）通过改变微生物和酶活性来影响土壤磷对养分添加的反应。了解土壤微生物和酶活性的动态变化对于预测未来草地土壤中的磷循环至关重要。