Effects of Simulated Warming on Soil Respiration Components in a Taxodium hybrid ‘Zhongshanshan’ Plantation

Warming profoundly influences soil respiration in terrestrial ecosystems, thereby altering global carbon cycling. Understanding the trends and drivers of soil respiration changes in forest ecosystems under warming is essential for assessing regional carbon budgets and ecosystem carbon sink/source dynamics. In this study, a one-year warming experiment was conducted using open-top chambers in a Taxodium hybrid (Zhongshanshan) ecosystem in the northern Jiangsu coastal area, China. Treatments included control (CK) and warming (W), focusing on soil respiration components (soil respiration, Rs; heterotrophic respiration, Rh; autotrophic respiration, Ra) and associated soil hydrothermal and nutrient factors. Results showed that both warming and season significantly affected Rs, Rh, and Ra, all exhibiting a unimodal seasonal pattern peaking in summer. Warming increased winter Ra by 117.39% (p < 0.001). Bivariate models (temperature and moisture) explained more variation in respiration (R2 = 0.720–0.893) than univariate models. Correlation analysis indicated that under control conditions, Rs components were significantly positively correlated with microbial biomass carbon (MBC), ammonium nitrogen (NH4+-N), and available phosphorus (AP). After warming, these positive correlations with MBC and AP persisted; however, negative correlations emerged with soil organic carbon (SOC) and its stoichiometric ratios (C:N, C:P). Additionally, Ra showed negative correlations with easily oxidizable carbon (EOC), total nitrogen (TN), and N:P. Overall, these findings suggest that climate warming may enhance soil respiration in the Taxodium hybrid (Zhongshanshan) ecosystem by altering soil thermal-hydrological and nutrient factors, although further validation is needed.