Nonnegligible role of warming-induced soil drying in regulating warming effect on soil respiration

Based on results of a 26-year soil warming experiment (soil temperature being elevated by 5 {degrees}C) in a Harvard hardwood forest, Melillo et al. demonstrated a four-phase pattern of long-term warming effect on soil respiration, while the mechanisms were not fully elucidated because they neglected the indirect effect due to warming-induced soil drying. By showing a significant correlation between precipitation anomaly and inter-annual variation of warming effect on soil respiration, we suggest a nonnegligible role of warming-induced soil drying in regulating the long-term warming effect on soil respiration. Our analysis recommends further efforts to consider both the direct and indirect (i.e., warming-induced soil drying) warming effects to gain more in-depth understanding of the long-term soil C dynamics.