Asymmetric soil respiration responses to pulse rainfall in thinned subtropical Cunninghamia lanceolata plantations
Description
We investigated the impact of rainfall events during the inactive growing season (winter) on soil respiration pulse in a subtropical Chinese fir ecosystem. Single rainfall events of varying intensities induced significant pulse effects on soil respiration. Although thinning reduced root biomass by 63.5%, it increased soil temperature by 0.4°C (17.4%) and microbial carbon content by 48.49 mg kg⁻¹ (37.9%). The reduction in root respiration balanced by increased microbial respiration resulted in non-significant changes in soil respiration pulse effects post-thinning. Soil respiration pulse effects were amplified under reduced and mildly increased rainfall compared to control conditions. However, under high-intensity rainfall, the pulse effect diminished, indicating an asymmetric response. Structural equation modeling revealed that sustained changes in rainfall altered soil aeration, influencing root and microbial growth and metabolism, leading to asymmetric soil respiration pulse effects.