Thresholds of Soil Moisture on the Temperature Response of Soil Respiration in Semiarid High-Altitude Grassland in Northwestern China

Abstract

Although soil temperature (T_s) is generally considered as the primarily factor influencing soil respiration (R_s), the correlation between soil respiration and soil temperature is often affected by soil moisture (M_s). In this study, we analyzed the correlation between R_s and T_s under different soil moisture condition in semiarid high-altitude grassland in northwestern China. The results showed that (1) when the values of M_s were higher than the field capacity (FC), R_s were mainly controlled by M_s. (2) FC was also an important threshold to affect the selection of R_s–T_s model and the determination of temperature sensitivity (Q₁₀). Our findings highlight that R_s is significantly influenced by M_s in a threshold manner, and FC is an important moisture threshold for R_s and its temperature response in high altitude semiarid ecosystems.We suggested that the effect of M_s on R_s cannot be neglected in high altitude semiarid ecosystems.