Study on the Natural Thinning of Even-aged Pure Masson Pine Plantation Construction and Application of Stand Growth Model for Natural Broad-leaved Forests in North Fujian The Natural Thinning and Structural Pattern of the Intermediate Cutting Intensity in the Cunninghamia lanceolata Stand AN EMPIRICAL MODEL DESCRIBING NATURAL THINNING PROCESS OF PLANT POPULATION Density and Biomass Dynamics of Pinus taiwanensis at Songyang County, Zhejiang Province