Photosynthetic and environmental regulations of the dynamics of soil respiration in a forest ecosystem revealed by analyses of decadal time series

Although photosynthetic and environmental regulations of the dynamics of soil respiration have been frequently reported, few studies have so far tested their generality and interactive effects. Using decade-long continuous measurements of soil respiration and eddy covariance records of net ecosystem exchange of CO₂ at a forest site in the central USA, we examined the linkage of photosynthesis and environmental factors with soil respiration. Results showed that gross primary production (GPP) regulated soil respiration with monthly mean time lags that varied between four to twelve hours. The variations in this time lag were affected by past trajectories of moisture and temperature. GPP played a more important role in regulating soil respiration during dry than wet seasons, probably due to stronger water limitation on soil respiration under dry conditions. Finally, we found that models incorporating GPP as an input explained more variation in soil respiration than using soil temperature and moisture alone. Our findings suggest that photosynthesis and environmental conditions interactively drive the dynamics of soil respiration.