Forest types control the contribution of litter and roots to labile and persistent soil organic carbon

Forest ecosystems contain a substantial terrestrial reservoir of soil organic carbon (SOC). Here, a “Detritus Input and Removal Treatments” experiment was conducted to explore the effects of litter and roots on soil labile, persistent, and total organic C (TOC) pools in the coniferous, broad-leaved, and coniferous-broad-leaved mixed forests (CF, BF, and CBF, respectively) in the subtropical and warm temperate transition zone in Henan province, eastern China. After 2–3 years of detritus manipulations, neither litter addition nor root exclusion affected soil temperature or moisture. In contrast, litter removal increased soil temperature but decreased soil moisture, regardless of forest types. Litter addition marginally decreased labile OC and TOC contents in the BF but not in the CF and CBF. Litter removal reduced labile OC and TOC contents in the CF and BF and persistent OC contents in the CF only. Root exclusion decreased labile OC contents in the CBF only, but reduced persistent OC and TOC contents in the CF and CBF. Structural equation models suggested that litter but not root manipulation altered SOC pools via changing soil temperature and moisture in the BF, whereas the effects of litter and root manipulation on SOC pools were not related to the changes in soil temperature and moisture in the CF and CBF. Our results suggest that the impact of litter and roots on SOC pools depends on forest types, which may indicate differential responses of SOC storage among forests under global change scenarios.