Abstract: Through the synecological investigation in different corranunity successional stages of erergreen broad-leaved forest of Tiantong National Forest Park in Zhejiang, the authors found that Pinas massoniana Lamb. is the dec]ming species iff the successional course of evergreen broad-leaved forest. For revealing the declining causes of P. massoniana, through measuring the habitat, especially the sun-light intensity, the authors have gained the knowledge that the low sun-light intensity in seral often made the seedlings and young trees of P. massoniana live in a condition below the compensation point of light; and the interference of other shade-tolerant evergreen broad-leaved species gradually impeded the growth of the adult trees of P. massoniana by weakening the ability of its material synthesis and intensifying the ability of material decomposition along with the community succession, and withered away gradually.

Key words: Pinus massoniana, Declining species, Succession, Evergreen broad-leaved forest