Abstract: Based on investigation data from a permanent secondary forest plot of 1ha in Mopan Mountains,Jilin city,the structure of Tilia mandshurica population was analyzed.Ripley's K function was used to analyze spatial patterns of T.mandshurica population at different growth stages (saplings,small trees and big trees).The results showed that DBH structure of T.mandshurica presented a reverse “J” distribution and small age individuals accounted more.The spatial pattern of T.mandshurica population was clump for all stems,saplings and small trees,but random for big trees; spatial associations between different stages were repulsed .It indicates that seed dispersal and regeneration mechanism was a key factor to spatial pattern.

Key words: Mopan Mountains, Tilia mandshurica, Ripley's K, spatial pattern, spatial association