Abstract: Heptacodium miconioides is a Chinese special monospermous plant under state Grade-Ⅱ protection and now the wild resource was few.Using Hegyi individual tree competition index model, the relation of intraspecific and interspecific competition in Heptacodium miconioides distributed at Tiantai mountain of Zhejiang Province was quantitatively analyzed.The results showed that the intraspecific competition intensity in Heptacodium miconioides decreased gradually with the increasing of forest tree diameter class and the interspecific competition in Heptacodium miconioides was stronger than those in associated tree species.The degressive order of the intraspecific and interspecific competition intensity in Heptacodium miconioides was interspecific competition, Fraximus insulsris, Lindera rubronewia, Cyclocarya paliurus, Acer davidii, Meliosma veitchiorum, Prumus vaniotii, Crytomeria fortunei and Alniphylium fortunei.The relationship between the competition intensity and the diameter at breast height of objective tree obeyed power function.The intraspecific and interspecific competition intensity in Heptacodium miconioides could be prognosticated using the model. The predicated results showed that the competition intensity became small and the range was not too large when the diameter at breast height of Heptacodium miconioides reached 20 cm.

Key words: Heptacodium miconioides, intraspecific, interspecific, competition index