Soil respiration of four forests along elevation gradient in northern subtropical China

Soil respiration is the second-largest terrestrial carbon (C) flux, and soil temperature and soil moisture are the main drivers of temporal variation in soil respiration and its components. Here, we quantified the contribution of soil temperature, soil moisture, and their intersection on the variation in soil respiration and its components of the evergreen broad-leaved forests (EBF), mixed evergreen and deciduous broad-leaved forests (MF), deciduous broad-leaved forests (DBF), and subalpine coniferous forests (CF) along an elevation gradient.

We measured soil respiration of four types of forests along the elevation gradient in Shennongjia, Hubei China based on the trenching experiments. We parameterized the relationships between soil respiration and soil temperature, soil moisture, and quantified the intersection of temperature and moisture on soil respiration and its components.

Total soil respiration (R _S), heterotrophic respiration (R _H), and autotrophic respiration (R _A) were significantly correlated with soil temperature in all four forests. The Q ₁₀ value of soil respiration significantly differed among the four types of forest, and the Q ₁₀ was 3.06 for EBF, 3.75 for MF, 4.05 for DBF, and 4.49 for CF, respectively. The soil temperature explained 62%-81% of the variation in respiration, while soil temperature and soil moisture together explained 91%-97% of soil respiration variation for the four types of forests. The variation from the intersection of soil temperature and moisture were 12.1%-25.0% in R_S, 1.0%-7.0% in R _H, and 17.1%-19.6% in R _A, respectively.

Our results show that the temperature sensitivity (Q ₁₀) of soil respiration increased with elevation. The intersection between soil temperature and soil moisture had strong effects on soil respiration, especially in R _H. We demonstrated that the intersection effects between soil temperature and soil moisture on soil respiration were essential to understand the response of soil respiration and its components to climate change.