Microbial genes for degrading plant-derived carbon are a key factor affecting soil respiration and temperature sensitivity in plateau peatlands

Abstract

Peatlands on the southwestern plateau of China are important carbon sinks for high-altitude terrestrial ecosystems in Asia. However, the specific microecological mechanism responsible for alterations in carbon processes in this region due to the simultaneous impacts of global warming and drought has not been fully elucidated. Investigating this mechanism will improve our understanding of carbon cycle feedback in peatland ecosystems, as it is affected by changes in hydrology and temperature, especially in vulnerable habitats. This study examined the influence of soil carbon decomposition functional microorganisms on soil respiration and temperature sensitivity (expressed as Q₁₀) in high-elevation peatlands using field investigations, simulated warming experiments, and metagenomic sequencing. We found that hydrothermal conditions had a significant effect on soil respiration, leading to an increase in cumulative soil respiration as soil moisture and temperature increased. Soil moisture affected soil respiration and soil organic carbon mainly through soil microorganisms, with a predominance of carbon-decomposing genes. We found that genes regulating the decomposition of plant-derived carbon such as cellulose and lignin were the critical factor influencing Q₁₀ in peatlands. Genes involved in cellulose and lignin decomposition showed a significant positive correlation with Q₁₀ (P < 0.05), while genes involved in hemicellulose decomposition showed a significant negative correlation with Q₁₀ (P < 0.05). Specifically, genes such as ACO, xylF, and hpaE, which are involved in lignin decomposition, and glgB, which is responsible for cellulose decomposition, showed significant positive correlations (P < 0.05) with Q₁₀. Conversely, the gene uxaC, involved in the decomposition of hemicellulose, showed a significant negative correlation (P < 0.05) with Q₁₀. Finally, we analyzed the relevant carbon metabolic pathways and found that although they were affected by water, they were not significantly related to Q₁₀. In short, this research highlights the importance of microorganisms with genes for decomposing plant-derived carbon in influencing carbon emissions in plateau peatlands during periods of warming.