Study on Logg ing Gaps Regenera tion in SecondaryBroad-leaved Forest in Changba iMounta in

The regeneration trait of logging gap s in relation to sizes and ages in secondary broad2leaved forest whichwas p redominated by Tilia am urensis, Acerm ono and Quercus m ongolica in ChangbaiMountain was studied. The research result showed that there were 42. 8% ( canopy gap s area 2) , 23. 8% (20～40 m2 ) , 33. 4% (40～60 m2 )in the p roportion of gap size. 38. 1% of gap s shape were rotundity and 61. 9% were oval. 38. 5% of the oval gap s layin N2S direction, 46. 2% inW-E direction and 15. 3% in N2E to S-W direction. These gap swere usually formed after3～4 trees logged which weremainly composed of Tilia am urensis, Quercusm ongolica andM aackia am urensis. The regeneration layerwas dominated by the shrub in non-gap stands but arbor in the gap s. Moreover, the dominance wouldrise with increasing sizes and ages of gap s. The species diversity and densitywere obviouslymore in gap s than in non-gap stands. The synthesis diversity had a tendency to decline with increasing sizes and ages of gap s. The dominancespecieswere different in gap s of different sizes, but were mainly composed of intolerant species.