烏心石為極具經濟價值的闊葉樹種，惟過往研究多偏重於生理、木材特性等方面，對於 烏心石之族群結構及天然更新等方面的研究缺如。本研究藉由一塊設置於本處溪頭營林區3林班 57-1 號造林地之烏心石覆層林長期試驗地之樣區，進行每木調查，其中以柳杉為主的針葉樹造林 木之徑級結構多呈鐘型曲線分布，而烏心石之徑級結構呈L型，顯示小苗數量雖多，但能夠長成小 樹的個體十分有限。

Michelia compressa is a broad-leaved species with high economic values. Past studies on M. compressa emphasized physiology, timber characteristics, and so on. Studies on population structure and natural regeneration of the tree species are rare. In this study, a plot was laid out in stand No. 57-1, 3rd forest compartment, Xitou area in the Experimental Forest, National Taiwan University. Distribution of DBH classes for Cryptomeria japonica, which is the main tree species, was bell-shape, but it was L-shape for M. compressa. This suggests that number of M. compressa seedlings are numerous, but only few individuals grow into small trees.