Microbial nitrogen and phosphorus co‐limitation across permafrost region

Abstract

The status of plant and microbial nutrient limitation have profound impacts on ecosystem carbon cycle in permafrost areas, which store large amounts of carbon and experience pronounced climatic warming. Despite the long‐term standing paradigm assumes that cold ecosystems primarily have nitrogen deficiency, large‐scale empirical tests of microbial nutrient limitation are lacking. Here we assessed the potential microbial nutrient limitation across the Tibetan alpine permafrost region, using the combination of enzymatic and elemental stoichiometry, genes abundance and fertilization method. In contrast with the traditional view, the four independent approaches congruently detected widespread microbial nitrogen and phosphorus co‐limitation in both the surface soil and deep permafrost deposits, with stronger limitation in the topsoil. Further analysis revealed that soil resources stoichiometry and microbial community composition were the two best predictors of the magnitude of microbial nutrient limitation. High ratio of available soil carbon to nutrient and low fungal/bacterial ratio corresponded to strong microbial nutrient limitation. These findings suggest that warming‐induced enhancement in soil nutrient availability could stimulate microbial activity, and probably amplify soil carbon losses from permafrost areas.

Potential nitrogen mobilisation from the Yedoma permafrost domain

“…For example, Mack et al (2004) showed that aboveground OC storage increased following N-addition, but was offset by increased OC decomposition-and thus soil OC losses-belowground. Similarly, Zhang et al (2023) found that a warming-induced, enhanced soil N supply stimulated soil microbial activity and amplified soil OC losses from permafrost soils in the Tibetan Plateau. These findings support the 'stoichiometric decomposition theory' , which suggests that N addition is beneficial for OM decomposition.…”

SWAMP: A new experiment for simulating permafrost warming and active layer deepening on the Tibetan Plateau

“…Meanwhile, thawing permafrost would release trapped nutrients (e.g. nitrogen), which would mitigate the nutrient limitation of plants and deep soil microbes, thus regulating the ecosystem carbon balance (Salmon et al, 2018; Zhang et al, 2023). These processes have not yet been fully quantified, which greatly constrains the ability of land surface models to accurately predict the potential permafrost C‐climate feedback (Miner et al, 2022; Schuur et al, 2015).…”

Microbial life‐history strategies mediate microbial carbon pump efficacy in response to N management depending on stoichiometry of microbial demand

“…Spearman's correlation analysis was conducted to analyze the relationship between soil environmental variables (pH, SOC, TN, NO 3 − , and NH 4 + ), stoichiometric imbalance (C/N, C/N imbalance, vector length and angle), microbial abundance, community composition, and life‐strategy, and MNC, NAC, MCP efficacy and carbon stability (hydrophobicity and MAOC), using the “corr.test” function in the psych package. A correlation modelling for critical factors was then established to determine the links among factors for MCP efficacy and MAOC (Zhang et al., 2023). Considering the strong correlation among the factors, the partial correlation was used to assess the relationship between MCP efficacy, MAOC and the various factors (Chen et al., 2019).…”