Gene-informed decomposition model predicts lower soil carbon loss due to persistent microbial adaptation to warming

Abstract

Soil microbial respiration is an important source of uncertainty in projecting future climate and carbon (C) cycle feedbacks. However, its feedbacks to climate warming and underlying microbial mechanisms are still poorly understood. Here we show that the temperature sensitivity of soil microbial respiration (Q10) in a temperate grassland ecosystem persistently decreases by 12.0 ± 3.7% across 7 years of warming. Also, the shifts of microbial communities play critical roles in regulating thermal adaptation of soil respiration. Incorporating microbial functional gene abundance data into a microbially-enabled ecosystem model significantly improves the modeling performance of soil microbial respiration by 5–19%, and reduces model parametric uncertainty by 55–71%. In addition, modeling analyses show that the microbial thermal adaptation can lead to considerably less heterotrophic respiration (11.6 ± 7.5%), and hence less soil C loss. If such microbially mediated dampening effects occur generally across different spatial and temporal scales, the potential positive feedback of soil microbial respiration in response to climate warming may be less than previously predicted.

No evidence for increased loss of old carbon in a temperate organic soil after 13 years of simulated climatic warming despite increased CO2 emissions

“…Although the rainfall inputs at the two sites differ by 20%, previous rainfall manipulation experiments across this climatic transect have shown that water is not a limiting factor, and that differences in thermal regimes dominate soil responses to transplantation (Ineson et al, 1998). Importantly, we did not find any evidence for microbial thermal acclimation (Crowther & Bradford, 2013;Guo et al, 2020;Ye et al, 2019) nor labile substrate depletion (Chen et al, 2020;Hartley et al, 2008Hartley et al, , 2012, which are the main explanations for previously reported progressive declines in CO 2 emissions with time after temperature increases. Unlike these previous experiments, we subjected, under natural conditions, plantsoil intact systems to simulated climatic warming over a long time period and thus allowed for the natural variations in the amount and composition of C forms that the plants return to soil (De Deyn et al, 2008).…”

High microbial diversity stabilizes the responses of soil organic carbon decomposition to warming in the subsoil on the Tibetan Plateau

“…Recent studies have attempted to uncover possible mechanisms by which changes in microbial traits (biomass, physiology, community composition, etc.) or key processes such as enzyme production regulate the response of SOC to warming (e.g., Alvarez et al, 2018; Ding et al, 2016; Guo et al, 2020; Karhu et al, 2014; Li et al, 2019; Nottingham et al, 2019; Walker et al, 2018). However, the results are context dependent and vary among different ecosystems.…”

Large‐scale evidence for microbial response and associated carbon release after permafrost thaw

“…Compared with the taxonomic diversity, functional genes could mediate biogeochemical cycles by exercising the corresponding ecological functional potentials through the enzymes encoded by genes. It has been reported that gene abundance could reflect the level of enzyme activity (Trivedi et al, 2016), and regulate the subsequent soil C mineralization (Burns et al, 2013; Feng et al, 2017; Guo et al, 2020; Manoharan et al, 2017; Taş et al, 2014; Wang et al, 2019; Xue, Yuan, et al, 2016). Exploring the responses of functional gene abundance and diversity to permafrost thaw is thus conducive to fully understand the regulatory role of microbes in permafrost biogeochemical cycles.…”