Response of cbbL Carbon-Sequestering Microorganisms to Simulated Warming in the River Source Wetland of the Wayan Mountains

As a globally critical carbon reservoir, the response mechanism of wetland ecosystems to climate change on the Qinghai-Tibet Plateau (QTP) has attracted significant scientific scrutiny. This study investigated the temperature sensitivity of cbbL-harboring carbon-sequestering microbial communities and their coupling with carbon-nitrogen cycle dynamics through a simulated field warming experiment conducted in the Wayan Mountains' river source wetland in the northeastern QTP. Key findings revealed that warming markedly elevated Alpha diversity (ACE and Chao1 indices), whereas Shannon and Simpson indices remained stable, indicating that temperature increases primarily altered community composition by enhancing species richness rather than evenness. Taxonomic analysis demonstrated significant increases in the relative abundances of Cyanobacteria and Actinobacteria, while Proteobacteria retained dominance but exhibited reduced relative abundance. At the genus level, <i>Thioflexothrix</i>, <i>Ferrithrix</i>, and <i>Rhodospirillum</i> dominated the community, with <i>Thioflexothrix</i> and <i>Ferrithrix</i> showing warming-induced abundance increments. Functional predictions indicated that warming preferentially stimulated heterotrophic and photoheterotrophic functional guilds. Soil physicochemical analyses further revealed warming-driven increases in nitrate nitrogen (NN), total carbon (TC), and total nitrogen (TN), concurrent with decreased soil moisture. Redundancy analysis identified TC as the predominant determinant of microbial community structure (followed by TN > NN), while pH and ammonium nitrogen (AN) exerted comparatively limited influence. Strong positive correlations between microbial communities and carbon/nitrogen indicators suggested that enhanced carbon-nitrogen resource availability served as the central driver of community succession. These findings elucidate the temperature-responsive mechanisms of cbbL-type carbon-sequestering microorganisms in alpine wetlands, offering critical insights for the adaptive management of carbon cycling in high-altitude ecosystems and advancing strategies toward achieving carbon neutrality goals.