Gap Features And Regeneration In The Broadleaved-Korean Pine Mixed Forest Of Xiaoxing'an Mountains

Gaps is one of the most important disturbance factors during the long-term change in theforest ecosystem, formation and change of gaps make up of the running setting structure of theforest landscape. The study of gaps disturbance is the basis of recognizing the dynamic changein the forest, simultaneity, understanding the recruitment dynamic of gaps can also provide thenecessary science bases for the continuable management and the keeping of the speciesdiversity.The basis characters of gaps were studied on the Broad leaved-Korean pine forest ofXiaoXingan Mountains. According to field survey data, the density of gaps was 22.33/hm~2,the total area of gaps was 27.69% of total survey area (9 hm~2), among which gaps with canopygap area of 25～1,025m~2, most of the gaps area were below 200m~2 and with the median of124.01m~2. There were 578 gap makers in the study, the mean was 2.88 in each gap; The maingap makers were breakage at rootstock and breakage at trunk, they made up of 45.54% and26.12% of the total gap makers. The species of gap makers were Pinus koraiensis, Abiesnephrolepis, Betula costata, Acer tegmentosum, Acer ukurunduense, Tilia amurense, Piceakoraiensis; When the diameter of canopy trees reach 20～40cm, these trees were likely to formthe gap by wind. Use point pattern to study the spatial distribution of gaps, the gaps showsuniformity when the scale under 25m, and other scales show randomly distributed, and therandom was stronger with the increasing of the gaps size.The quantitative characters and the responds were also investigated for the gap area ofseedlings (H＜1m), saplingⅠ(H≥1m, DBH＜2cm)and saplingⅡ(2cm≤DBH＜5cm)betweengaps and non-gaps in the Broad leaved-Korean pine forest of XiaoXingan Mountains. Theformation of gaps increased density of saplingⅠand saplingⅡin the arbor layer, but notsignificant (P＜0.05); The total density of seedlings and saplingⅠwhich grown in the shrublayer in gaps were lower than non-gaps, but the saplingⅡshowed the opposite result,significant differences(P＜0.05) in seedlings and saplingⅠbetween gaps and non-gaps, but notsignificant (P＜0.05) in saplingⅡ; Most of the densities of seedlings, saplingⅠand saplingⅡbetween species were not significant(P＜0.05). The total densities of seedlings and young treesin the arbor layer were highest between gaps whose size ranged from 401-600m~2; The totaldensities of seedlings and saplingⅠin the arbor layer were highest between gaps whose sizeranged from 201-400m~2 and 601-800m~2, but the trend of saplingⅡwas not significant.Different species had different regeneration responses in different development phases, most ofthe seedlings and young trees species in the arbor layer appears the single-apices distribution,the regeneration of seedling and saplingⅠwas better in the gaps whose size ranged from 201- 400m~2 and 601-800m~2, however the regeneration of saplingⅡwas better in the gaps whosesize ranged from 401-600m~2, in contrast, fir seedling was better in the gaps whose size≤200m~2;Most of the seedlings and young trees in the shrub layer grown better in the gaps whose sizeranged from 201-400m~2 and 601-800m~2.Species richness and Shannon-Wienner index were used to analyse the species diversitybetween gaps and non-gaps on the Broad leaved Korean pine forest of XiaoXingan Mountains.The results were listed following: tree species diversity index of seedlings and young trees inthe gaps was higher than non-gaps, not significant (P＜0.05); The shrub species diversity indexof seedlings in the gaps was a little higher than non-gaps, but the sapling was object, thediscern of species diversity of seedling and saplingⅠbetween gaps and non-gaps wassignificant (P＜0.05); but saplingⅡwas not significant. Species richness of seedlings andsapling showed the trend of single-apices with the increased of gaps area, but the biggest valueappeared in different areas; The Shannon-Wienner index of seedlings showed the trend ofdouble-apices with the increased of gaps area, and the biggest value appeared in the gapswhose size ranged from 201-400m~2; The Shannon-Wienner indexes of saplingⅠand saplingⅡwere both showed the trend of single-apices with the increased of gaps area, and the biggestvalue were appeared in the gaps whose size ranged from 401-600m~2 and 601-800m~2. Thenumber of shrub species of seedlings and sapling was not increased with the increasing of thegaps area, the biggest Shannon-Wienner indexes of seedlings and saplingⅠwere bothappeared in the gaps whose size＞800m~2, but the biggest Shannon-Wienner index saplingⅡwas appeared in the gaps whose size≤200m~2.