In this study

we selected leaf litters of four planted forests including Cercidiphyllum japonicum

Betula utilis

Pinus yunnansinsis

and Picea asperata as test objects.Their residual rate

total C and Ncontents

and the release dynamics of C and N at decomposing stage were determined in order to provide theoretical guidance for selecting the best tree species in the experimental area.The results indicated that thedecomposition rates of different withered leaves varied significantly.Mixture leaf litters of Picea asperatawith Betula utilis

Pinus yunnanensis and Betula utilis

Cercidiphyllum japonicum with Pinus yunnanensshowed obvious positive interaction in decomposition.No interaction was observed in those of P .asperataand C.japonicum.Furthermore

the decomposition rate of the mixed leaf litters from broad-leaved forestswas larger than that from needle-leaved forests.It is proved that broad-leaved forest stand was propitious tothe decomposition of leaf litter.The C contents of littered leaves showed decreasing trends while their C releasing rates increased during the decomposition process.Both the contents and releasing rates of C werehigher in needle-leaved forests.In contrast

the N content of leaf litter of the Cercidiphyllum japonicum

the Picea asperata and the Pinus yunnansinsis increased at the beginning then decreased

while that of theB.utilis showed a complex decreasing-increasing-decreasing trend.The mixture of the needle-leaved forestsand the broad-leaved forests promoted the releases of C and N from the needle leaf litters.