Abstract: The population structure and distribution pattern of Heptacodium miconioides, a rare plant in the Tiantai Mountain of Zhejiang province were studied in the paper. The size classes of the population structure can be divided as follows according to their proportion: class Ⅳ, medium_size trees and class Ⅲ, small trees. But there was no class Ⅰ, seedling. The population age structure belong to mid senescent type. As for the height class structure, the trees of 6-8 metres height were the most numerous, up 28.45% of the total; the trees of 8-10 metres height were 21.97%; the tallest trees were less than 14 metres. The whole population was characterized with the clump, including both the class Ⅲ small trees and the class Ⅳ medium size ones. However, the class Ⅴ, big trees was featuring the uniform distribution. The clump intensity was gradually reduced from the small trees to the big ones.

Key words: arbuscular mycorrhizal fungi (AMF), nitrogen, metabolism pathway, ecosystem.