在杉木幼林的生长过程中,林分内每个立木个体树冠大小和发育状况,反映了立木营养面积的大小。随着林木的生长,胸径愈来愈粗,树冠的冠幅也愈来愈大,因此,林冠大小与立木胸径之间存在着密切的相关关系。利用杉木生长的这种特点,以林分平均直径来确定该林分每亩应保留的立木株数,即最适密度,籍以保证每株立木有适宜的营养空间。 In the growth process of young Chinese fir plantations, the size and development status of individual canopy trees in the stand reflect the size of standing tree nutrition area. With the growth of trees, the diameter at breast height is more and more thick, and the crown of crowns is also getting larger and larger. Therefore, there is a close correlation between the crown size and stand diameter. The use of the characteristics of Chinese fir growth, the average diameter of the forest stand to determine the number of trees per acre should be retained, that is, the most appropriate density, to ensure that each tree stands have appropriate nutrition space.