Gap Dynamics In The Korean Pine Broad-leaved Forests

This thesis deals with gap dynamics in Korean pine broad—leaved forests in the Changbai Mountain and in Jiaohe, northeastern China. Natural disturbance regimes of gaps,tree species regeneration responses to gaps, and some structural characteristics of stands in the Korean pine broad —leaved forests were studied.The patterns of gap disturbances were investigated. Some parameters related to gap disturbance such as size and age structure of gaps,distribution patterns of gaps,diameter,height and decay class structure of gap makers, the numbers of gap makers forming a gap,turnover rate of gap disturbance, manners of gap formation as well as percentage of gap area in the Korean pine broad — forest landscapes were described and discussed in detail. Compared with those in the Korean pine broad — leaved forest in Jiaohe,the percentage of gap area in the Korean pine broad —leaved forest in the Changbai Mountain is greater, the average size of gaps is larger, the turnover rate of gap disturbance is faster. Most of the gaps in the Korean pine broad—leaved forest in the Changbai Mountain were formed by 1 — 4 gap makers; but in Jiaohe, they were mainly formed by one gap maker. In the Korean pine broad —leaved forest in the Changbai Mountain,gaps mostly resulted from uprooting treefall and then from stem breakage,while in Jiaohe,compared with uprooting treefall,stem breakage contributed more in the formation of gaps. The spatial distribution patterns of gaps in the Korean pine broad — leaved forests belong to the uniform or random types, which, to some extent, were caused by the distribution patterns of main big trees in the canopy layer. Major gap makers in the Korean pine broad — leaved forest in the Changbai Mountain were Pinus koraiensis, Fraxinus mandshurica, Quercus mongolica, and Tilia amurense,but those in Jiaohe were Pinus koraiensis, Abies holophylla,Betula costata,and Picea jezoensis. The probabity of making gaps was greatest when the trees in the Korean pine broad— leaved forests got D. B. H. 40 —80cm and height 25 —30m. Decay conditions of gap makers differed with species types.The quantitative characteristics of tree species in gaps differed from those in non—gap stand. The total density of all tree species in gaps is greater than that in non—gap stand .but, the total dominance of all tree species in gaps is smaller than that in non —gap stand. The densities of most tree species in gaps are greater than their correspondent densities in non — gap stand, but the degree of density increase in gaps for different species is different. Generally , the dominances of most of the big statured tree species in gaps are smaller than those in non —gap stand,while the dominances of middle or small statured tree species in gaps are greater than those in non —gap stand. The importance values of the same species in gaps and in non—gap stand are different. Based on the differences of orders of importance values of tree species in gaps and in non—gap stand,the tree species in the Korean pine broad — leaved forests in the Changbai Mountain and in Jiaohe were classified into three ecological groups respectively,i. e. the severe responsive(to gap disturbance)group,the moderate responsive(to gap disturbance) group, and the no significant responsive (to gap disturbance) group. Gaps enhanced the species richness, increased the species diversity, and made the coexistence of different species possible. With the alternation of gaps and non —gaps in the Korean pine broad —leaved forests.the relative dominance...