Increased litter input increases litter decomposition and soil respiration but has minor effects on soil organic carbon in subtropical forests

This study investigated the effects of changes in litter quantity and quality on litter decomposition, soil respiration, and soil organic carbon (SOC) in subtropical forests. The experiment had a nested factorial design with three factors: (1) successional stage with three levels (early, mid and mature), (2) litter type with two levels (Schima superba Gardn. et Champ. and Ormosia pinnata (Lour.) Merr.), and (3) litter addition with five levels (0, 218, 436, 654 and 873 g·m−2·yr−1, respectively). In all forests, an increase in litter input increased litter decomposition, litter carbon (C) loss and soil respiration but did not alter SOC content after 2.5 years. The increases in litter decomposition, litter C loss, and soil respiration in response to increased litter input were greater with the lower quality Schima superba litter than with the higher quality Ormosia pinnata litter. Litter quality did not affect SOC content at any of the three forest sites. The responses of litter decomposition and soil respiration to increasing litter input differed depending on forest successional stage. In subtropical forests, increases in litter production under climate change may accelerate C cycling. Net soil C storage in subtropical forests, however, may not change over short time scales in response to increased litter input.