Thermal sensitivity of soil organic carbon decomposition in riparian ecosystems

The soils of riparian ecosystems harbor a significant amount of organic carbon (C) and are susceptible to anthropogenic disturbances. However, the warming response of soil organic carbon (SOC) decomposition in riparian ecosystems has received limited attention.

In this study, we quantified the thermal sensitivity (Q₁₀) of SOC decomposition across a mean annual precipitation (MAP) gradient ranging from 1270 to 1416 mm in the riparian zones of the Three Gorges Reservoir.

Our findings indicate that the Q₁₀ ranged from 1.1 to 2.1. Notably, MAP exerts a negative effect on Q₁₀ by positively affecting the decomposability of SOC (D_SOC) and soil pH, collectively explaining 52.5% of the variation in Q₁₀. Among the factors studied, D_SOC emerged as the most critical determinant of Q₁₀ variation. The observed negative correlation between D_SOC and Q₁₀ suggests that stable SOC is more susceptible to loss under warming compared to active SOC.

Consequently, MAP-driven changes in D_SOC significantly influence the soil C cycle feedback to climate warming in riparian zone ecosystems. Specifically, locations with greater MAP are likely to experience stronger positive feedback from SOC loss in response to warming.