Effects of Warming on the Stoichiometry of Soil Microbial Biomass and Extracellular Enzymes in an Alpine Shrubland
The alpine shrub ecosystems on the Qinghai-Tibetan Plateau are experiencing significant warming. Revealing the effects of warming on the soil microbial metabolic activity will provide insights into soil carbon (C) and nutrient cycling under climate change. A five-year warming experiment was conducted in a Sibiraea angustata -dominated alpine shrub ecosystem on the eastern Qinghai-Tibetan Plateau to test the effects of warming on the soil microbial biomass, extracellular enzyme activities and their stoichiometry and soil physicochemical properties. The results showed that the effects of warming on the soil microbial biomass C, nitrogen (N) and phosphorus (P) varied with the growing season. Warming significantly increased the activities of C-acquiring enzymes (β-glucosidase, BG) by 7.5%-15.1% throughout the growing season and the activity of polyphenol oxidase (PPO) by 6.5% during the early growing season, indicating that warming would strengthen microbial C limitation and increase degradation of soil labile and recalcitrant C components. Warming significantly increased the activity of P-acquiring enzyme (acid phosphatase, AP) by 14.6% and trigger microbial P limitation during the late growing season, which might be a result of an increasing alpine shrub P uptake. Warming did not significantly affect the total activity of N-acquiring enzymes throughout the growing season mainly due to higher soil N availability. However, warming did not significantly affected the stoichiometry of soil extracellular enzymes throughout the growing season, except for an decreasing in enzyme N:P ratio during the early growing season. Moreover, the microclimate (air and soil temperature) and soil available nutrients (soil dissolved organic C, NH 4 + -N, available P and C:P), in addition to soil pH accounted for most variations in soil microbial biomass, extracellular enzyme activities and their stoichiometry in response to warming. Our results suggest that warming may trigger and strengthen soil microbial C and P limitation druing the growing season, and thus accelerate soil C loss and nutrient cycling in these alpine shrub ecosystems on the Qinghai-Tibetan Plateau
Year of publication: |
[2022]
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Authors: | Ma, Zhiliang ; Chen, Yamei ; Xu, Wenjuan ; Liu, Mei |
Publisher: |
[S.l.] : SSRN |
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