Substrate availability and not thermal acclimation controls microbial temperature sensitivity response to long‐term warming

Abstract

Microbes are responsible for cycling carbon (C) through soils, and predicted changes in soil C stocks under climate change are highly sensitive to shifts in the mechanisms assumed to control the microbial physiological response to warming. Two mechanisms have been suggested to explain the long-term warming impact on microbial physiology: microbial thermal acclimation and changes in the quantity and quality of substrates available for microbial metabolism. Yet studies disentangling these two mechanisms are lacking. To resolve the drivers of changes in microbial physiology in response to long-term warming, we sampled soils from 13-and 28-year-old soil warming experiments in different seasons. We performed short-term laboratory incubations across a range of temperatures to measure the relationships between temperature sensitivity of physiology (growth, respiration, carbon use efficiency, and extracellular enzyme activity) and the chemical composition of soil organic matter.We observed apparent thermal acclimation of microbial respiration, but only in summer, when warming had exacerbated the seasonally-induced, already small dissolved organic matter pools. Irrespective of warming, greater quantity and quality of soil

Pangenomes reveal genomic signatures of microbial adaptation to experimental soil warming

“…We examined genomic signatures of bacteria exposed to three decades of climate warming to understand whether warmer soils select for certain taxa, or if evolution also leads to local adaptation. Based on an average generation time of two weeks for soil microbial communities estimated using 18O-labeled water, 30 years corresponds to about 500 generations in this system [32]. In a reciprocal transplant study across a natural temperature gradient, ecological and evolutionary feedbacks were detected on a timescale of 1.5 years [38].…”

“…Our previous works indicate ecological filtering in heated plots in response to decreases in carbon quality and quantity [18] that likely selects for microbes able to degrade more recalcitrant carbon substrates [24]. Long-term warming causes thermal acclimation of soil respiration [30, 31], and though this effect may be seasonal [32], adaptive processes may also be important. Microbial thermal adaption likely involves physiological trade-offs altering growth rate and efficiency [33].…”

Back to the ‘roots’ of research: a hypothesis‐driven approach provides predictive understanding of plant–herbivore–microbe interactions

“…A recent study showed how the exclusion of microbial species allowed other microorganisms to occupy the niches of those recently excluded species with resulting shifts in nitrogen and carbon cycling (Romdhane et al ., 2022). Future studies should help elucidate how changes in plant inputs into soil are related to shifts in soil functioning (Domeignoz‐Horta et al ., 2023).…”

Effects of whole‐soil warming on CH4 and N2O fluxes in an alpine grassland

“…As elevated temperature could directly alter microbial metabolism or indirectly change soil microclimate, substrate quantity and quality, gas diffusion, the input of plant litter, and nutrient availability, thus affecting the microbial activity and associated GHGs fluxes (Domeignoz-Horta et al, 2022;Martins et al, 2017;Xu et al, 2013;Yu et al, 2022). CH 4 is taken up by methanotrophic microbes under aerobic conditions and released by methanogens under anaerobic conditions (Dunfield et al, 1993;Lai, 2009), and CH 4 is generally absorbed by soil as a potential carbon sink (Heinzle et al, 2023;Wang et al, 2021).…”