Abstract: The formation of self-sustaining mechanism is one of the major objectives for the sustainable management of plantations.In this study,the incorporation of different proportions of native Michelia macclurei into Cunninghamia lanceolata plantation was practiced to restore the degraded C.lanceolata plantation,and the comparison of nutrient cycling characteristics and soil nutrient concentrations was made among four types of plantation stand with different mixed rate of native M.macclurei representing four different restoration stages of degraded C.lanceolata plantations.With the increase of the proportion of M.macclurei in the plantation,the litterfall and returned nutrients N,P,K,Ca and Mg increased.The nutrient cycling efficiency increased significantly, e.g.,that of N and Mg increased from about 0.1 for the degraded pure C.lanceolata plantation to above 0.5 for the pure M.macclurei plantation.Soil organic matter and nutrients also elevated.It is suggested that the self-sustaining mechanism of the C.lanceolata plantation forest gradually reformed as the proportion of native M.macclurei mixed in the plantation increased. The criteria to determine the proportion of native broad-leaved tree species mixed in C.lanceolata plantations for the purpose of sustainable management should be based on whether the self-sustaining mechanism was reformed and whether the soil nutrient status was improved.

Key words: Mixing of Cunninghamia lanceolata with Michelia macclurei, Nutrient-sustaining mechanism, Nutrient cycling efficiency, forest, composition, tree species, association between families., distribution