Local temperature increases reduce soil microbial residues and carbon stocks

Abstract

Warming is known to reduce soil carbon (C) stocks by promoting microbial respiration, which is associated with the decomposition of microbial residue carbon (MRC).However, the relative contribution of MRC to soil organic carbon (SOC) across temperature gradients is poorly understood. Here, we investigated the contribution of MRC to SOC along two independent elevation gradients of our model system (i.e., the Tibetan Plateau and Shennongjia Mountain in China). Our results showed that local temperature increases were negatively correlated with MRC and SOC. Further analyses revealed that rising temperature reduced SOC via decreasing MRC, which helps to explain future reductions in SOC under climate warming. Our findings demonstrate that climate warming has the potential to reduce C sequestration by increasing the decomposition of MRC, exacerbating the positive feedback between rising temperature and CO 2 efflux. Our study also considered the influence of multiple environmental factors such as soil pH and moisture, which were more important in controlling SOC than microbial traits such as microbial life-style strategies and metabolic efficiency.Together, our work suggests an important mechanism underlying long-term soil C sequestration, which has important implications for the microbial-mediated C process in the face of global climate change.

Climate warming alters the relative importance of plant root and microbial community in regulating the accumulation of soil microbial necromass carbon in a Tibetan alpine meadow

“…We found a positive effect of climate warming on MNC formation and stabilization, but long‐term, high‐magnitude warming may decrease the accumulation and contribution of soil MNC to SOC (Figure 6). This is consistent with previous findings that high temperatures impact MNC negatively (Zeng et al, 2022), which may be resulted from restricted accumulation of soil MNC via a reduction in plant biomass production and microbial activity (Beidler et al, 2020). Moreover, the inhibiting effects of lower moisture conditions on C‐ and N‐ acquiring enzyme activity in high‐level warming may also constrain the accumulation and contribution of MNC to SOC.…”

“…The microbial community features play a vital role in mediating MNC accumulation under different warming scenarios (Figures 6, Yang et al, 2020; Zeng et al, 2022). The formation of MNC is mediated by the iterative process of cell biosynthesis, growth, and death.…”

“…Then, adjusted cell maintenance and growth caused by varied microbial community characteristics can further result in different patterns of MNC accumulation. Previous studies have documented faster turnover and growth rates of copiotrophs (r‐strategists) than those of oligotrophs (K‐strategists), which may increase microbe residue productions (Shao et al, 2021; Zeng et al, 2022). Thus, the changes in microbial taxa associated with climate warming can also affect the efficiency of MNC formation and accumulation due to their different life‐history strategies, which is supported by the significant relationship between BNC and the ratio of bacterial oligotrophs/copiotrophs taxa in our study area (Figure S8).…”

“…Normally, soil saprobes can promote the decomposition of plant litter, provide a sustainable nutrient source for microbial biomass synthesis and increase microbial residue yields (Gessner et al, 2010;Liu et al, 2023). The high dependence of FNC on soil saprobes were further corroborated by the recent findings that the variations of MNC may change with unique fungal functional groups (Zeng et al, 2022). However, though sequencing data can identify the taxonomic identity of the microbes present in a sample, we lack a comprehensive understanding of the functional characteristics associated with unculturable taxa.…”

Earthworm-invaded boreal forest soils harbour distinct microbial communities

“…Additionally, the lower relative abundance of the oligotrophic Acidobacteriota and Chloroflexi and the higher relative abundance of the copiotrophic Bacteroidota further illustrate that the microbial community is more adapted to higher C availability in earthworm-invaded mineral soils (Fierer et al, 2007;Zeng et al, 2022). Bacteroidota, as well as Chitinophagaceae, are also often positively correlated with high N additions in boreal forests (Högberg et al, 2014), which aligns with the numerically higher TN content of invaded mineral soils (Table S1).…”