Soil carbon loss with warming: New evidence from carbon‐degrading enzymes

Abstract

Climate warming affects soil carbon (C) dynamics, with possible serious consequences for soil C stocks and atmospheric CO2 concentrations. However, the mechanisms underlying changes in soil C storage are not well understood, hampering long‐term predictions of climate C‐feedbacks. The activity of the extracellular enzymes ligninase and cellulase can be used to track changes in the predominant C sources of soil microbes and can thus provide mechanistic insights into soil C loss pathways. Here we show, using meta‐analysis, that reductions in soil C stocks with warming are associated with increased ratios of ligninase to cellulase activity. Furthermore, whereas long‐term (≥5 years) warming reduced the soil recalcitrant C pool by 14%, short‐term warming had no significant effect. Together, these results suggest that warming stimulates microbial utilization of recalcitrant C pools, possibly exacerbating long‐term climate‐C feedbacks.

Controls on Soil Organic Matter Degradation and Subsequent Greenhouse Gas Emissions Across a Permafrost Thaw Gradient in Northern Sweden

“…Uncovering mechanisms to maintain microbial diversity in these environments is important in understanding belowground metabolic transformations and subsequent GHG emissions (Muscarella et al, 2019). Substrate generalists vs. specialists can interact with different available substrates and depending upon the substrates that are used, we can partly understand microbial preferences and predict gas flux changes (Chen et al, 2020;Zhou et al, 2020). Based on our data, bog SOM exhibited higher DOC porewater concentrations, lower microbial diversity (inferred from Shannon diversity; Singleton et al, 2018;Woodcroft et al, 2018), and activity (inferred from the high average number of neighbors and lower clustering coefficient in the bog metabolic transformations analysis- Supplementary Table 3), suggesting that bog microbial communities are comprised of substrate specialists that are only capable of performing a limited set of specific functions (Monard et al, 2016;Muscarella et al, 2019) under anoxic and acidic conditions mainly created by Sphagnum spp.…”

Long‐term nitrogen loading alleviates phosphorus limitation in terrestrial ecosystems

“…For example, N loading rate was grouped by <5, 5–15 and >15 g N m −2 year −1 and N loading frequency by <4, 4–12 and >12 times per year. To assess temporal variation in treatment effects, we made a distinction between short‐term (<5 years) and long‐term (≥5 years) studies (Chen et al., 2020; Kuebbing et al., 2018). The cutoff of 5 years aligned with the large survey of long‐term research in ecology and evolution by Kuebbing et al.…”

Linking microbial functional gene abundance and soil extracellular enzyme activity: Implications for soil carbon dynamics

“…In Moore et al (2020), they show the divergent responses of the abundance of genes encoding hydrolytic and oxidative enzymes to N loading, which are in line with the contrasting responses of hydrolytic and oxidative carbondegrading enzyme activity . In , Chen, Luo, García-Palacios, et al (2018) and Chen et al (2020), we demonstrate that shifts in soil hydrolytic and oxidative C-degrading enzyme activities are closely associated with soil C stock under N loading and experimental warming. Therefore, there can be direct and indirect relationships between shifts in microbial function gene abundance and changes in soil C stock, constituting one future research priority (highlighted by the dashed red arrows).…”