Gap Phase Regeneration in Mid-Subtropical Evergreen Broad-Leaved Forest in Wanmulin, Fujian Dynamics of Species Composition and Regeneration Rules in the Gaps of Pinus bungeana forest Gaps in Huanglong Mountain,Shaanxi Province REGENERATION RESPONSE OF MAIN TREE SPECIES TO GAP SIZE AND GAP DEVELOPMENT PHASE IN THE KOREAN PINE-BROADLEAVED FOREST IN JIAOHE,NORTHEAST CHINA