Study on Seedling Regenera tion of Arbor and Shrub in Logg ing Gaps inPopu lus davidiana-B e tu la pla typhylla Secondary Forests in Changba iMounta in Study on Logg ing Gaps Regenera tion in SecondaryBroad-leaved Forest in Changba iMounta in A preliminary study on N2O and CH4 emissions from differentsoils on northern slope of Changbai Mountain CO2 concentration character in broad-leaved Korean pine forest of Changbai Mountains Effect of elevated CO2 concentration on growth of dominant tree species in pine broadleaf forest of Changbai mountain