Comparative Analysis of Soil Respiration Dynamics and Heterotrophic Respiration Sensitivity to Warming in a Subalpine Coniferous Forest and a Subtropical Evergreen Broadleaf Forest in Southwest China

To quantify variations in the components of soil respiration (Rs), elucidate the impact of warming on heterotrophic respiration (Rh) in subalpine coniferous forest (LJ) and in subtropical evergreen broadleaf forest (ALS), and discern differences in the dominant regulating factors of soil respiration components between the two forest ecosystems. This study used multichannel automated soil efflux chambers with three treatments: control (CK), trenching (NR), and trenching with warming (NRW) in LJ and ALS in Southwest China. The results reveal that Rs was higher in ALS than in LJ, and the ratio of Rh to Rs was significantly higher in LJ than in ALS. Although soil temperature (ST) and soil moisture (SM) also identified the main controlling factors of Rs, Rh, Ra, and the warming effect of Rh when considering carbon cycle modeling, the sensitivity of Rs to temperature (Q₁₀) was not significantly different between Rs, Rh, and Ra for both forests. The greater warming effect on Rh in LJ than in ALS is due to the combination of lower temperatures, recalcitrant organic matter, and slower litter decomposition in subalpine coniferous forests. This study confirmed that Rs, Rh and Ra had positive correlation with ST and SM for two ecosystems. This study has proven that the greater the warming effect of Rh is, the greater the contribution of Rh to Rs becomes, and the lesser the contribution of Ra to Rs in LJ becomes compared to that of ALS.