We determined the in situ decomposition of leaf litter and fine roots of Erythrophleum fordii and Castanopsis hystrix in subtropical China using the nylon mesh-bag method. The results indicated that the decomposition coefficients for leaf litter and fine roots of E. fordii and C. hystrix were 0.98 a^-1 and 0.88 a^-1 and 0.65 a^-1 and 0.59 a^-1, respectively. Decomposition rates for leaf litter and fine roots were primarily influenced by the chemical properties of the litter, rather than by the environmental factors in the plantations. During the initial phase, the percentage of dry mass loss was positively correlated with N content (R²=0.525 and 0.549, respectively) and negatively correlated with the C/N ratio (R²=0.764 and 0.361, respectively) for leaf litter and fine roots. During the late phase of decomposition, decomposition rates were positively correlated with N content (R²=0.565 and 0.511, respectively) and negatively correlated with lignin content (R²=0.525 and 0.519, respectively), C/N (R²=0.482 and 0.574, respectively), and lignin/N ratios (R²=0.523 and 0.486, respectively) for leaf litter and fine roots. The significant correlation between leaf litter and fine root decomposition rates could be attributed to the similar effects of chemical properties on decomposition rates.