Biotic and abiotic factors jointly drive the temperature sensitivity of soil respiration in forests worldwide

Abstract

The sensitivity of soil respiration (R_s) to temperature (Q₁₀) is a key parameter for benchmarking the carbon (C) cycle and climate feedbacks in the context of global warming. However, previous studies on the factors that drive forest soil Q₁₀ have focused mostly on abiotic factors, such as climate and soil, while the role of biotic factors has been less examined. Here, we compiled a global dataset of 766 soil Q₁₀ values and 17 matched biotic and abiotic factors to explore the factors that drive the variability of global forest soil Q₁₀ using a random forest (RF) model. Our findings showed that soil Q₁₀ increased with microbial biomass carbon (MBC), which was the most important predictor. Additionally, soil Q₁₀ was positively correlated with leaf phosphorus content (LPC) but was negatively correlated with leaf N:P, indicating that plant ecological stoichiometry might be a factor that explained soil Q₁₀ variability. All abiotic factors, including climate, soil properties, and elevation, had great predictive power and were significantly related to soil Q₁₀. By comparing the soil Q₁₀ in multispecies forests and monocultures, we found that Q₁₀ in the mixed needle-leaved and broad-leaved forests (NF & BF) was lower than in monocultures. Our study revealed that, in addition to abiotic factors, biotic factors were also strong predictors of forest soil Q₁₀, which can deepen our understanding of soil respiration in response to global warming and provide insights for improving carbon cycle models.