Subtropical plantations have been undergoing understory removal and increased plant litter inputs due to global change and anthropogenic activities. However, how understory removal and increased litter inputs affect litter decomposition is still unclear in these plantations. Using a field manipulation experiment, we assessed the effects of understory removal and litter addition on decomposition rates of leaf litter, twig litter, and mixed leaf and twig litter over 16 months of incubation in a subtropi cal Chinese fir (Cunninghamia lanceolata) plantation in southern China. We also exam ined the changes in soil chemical properties and fungal and bacterial phospholipidfatty acids (PLFAs) after understory removal and litter addition. Litter decomposition rates were inhibited by understory removal due to the decreased fungal PLFAs and the associated declines in the ratio of fungal to bacterial biomass. Litter addition also re-tarded litter decomposition rates, despite the increases in soil NH4+-N concentra tion and fungal PLFAs. However, both litter decomposition rates and soil microbialPLFAs remained unchanged in the presence of both understory removal and litter addition. In all treatments, mixed leaf and twig litter produced additive effects on lit ter decomposition rates. These results suggest that understory removal and litter addition interact to affect litter decomposition dynamics and highlight that litter mix ture decomposition rates could be easily predicted from component litter in subtropi cal Chinese fir plantations of southern China.