Study On Population Dynamics And Spatial Pattern Of Poplar-Birch Forests In Taiyue Mountain Of Shanxi Province

The purpose of this thesis is to better understand the plantcommunity dynamics, the maintenance of species biodiversity, andthe species spatial distribution in Taiyue Mountain Nature Reserve ofShanxi province. Choosed through the density of polar-birch forestwas established for3community in2013, with the target species ofpolar-birch forest. Based on the field investigation, polar-birch forestand community characteristics for Taiyue Mountain were studiedsystematically and comprehensively by using quantitative ecologymethods. The community structure characteristics, distributionalpattern and interspecific segregation were studied, which are thesientific basis for the efficient conservation of polar-birch forest. Theecological parameters used in the study included the age structure,the spatial distribution seedlings, and the relevant correlations, toanalyze the succession, stability and development trend atcommunity level. The preliminary results were got as following:（1）The static life table of polar-birch forest was worked outthrough“space instead of “time” method, showed that Populusdavidiana and Betula platyphylla population survival curves have thesame change trend in3communities of Mountain Taiyue, the survivalcurve of the population tended to the DeeveyⅠ-Ⅱ, reflected thepopulation dynamic changes, meanwhile Introducted survival analysis of the survival function, cumulative mortality rate function,mortality density function and hazard rate function, to study thepopulation of structure and dynamics. The results showed Populusdavidiana population most individuals concentrated in the ageⅡ andⅢclass(70.91%), indicating that the population was in the decline stage.The peak of mortality was fromⅡ t o Ⅲdiameter class, and the deathrate of the population was higher in the later stage than in the formerstage. Betula platyphylla population most individuals concentrated inthe age Ⅱa nd Ⅲclass(60.39%), indicating that the population was inthe decline stage. The peak of mortality was fromⅡ to Ⅲd iameter class,and the death rate of the population was higher in the later stage thanin the former stage. The population was stable in the wholecommunity at the present stage. The functions used in the static lifetable could well explain the structure and dynamics of polar-birchforest. The regeneration of the population was of decline stage andunstable at old stage.（2） The survivorship curve of Populus davidiana populationgenerally matches a Deevey Type Ⅰ, although seedlings are rare andhave a low survival rate due to high crown density. The spatialdistribution patterns of the population differ among plots and growthperiods. The distribution pattern tends to be clumped on the easternslope of Taiyue Mountain peak where interspecific competition is notintense. The spatial distribution in different growth periods isclumped or random. Clustering is more pronounced for adult treesthan old trees as a result of biological and environmental factors.Populations tend to clump when interspecific competition is notsevere in a wet, cold, sunny habitat in Taiyue Mountain. In traspecific competition also affects the clustering intensity of different growthperiods.The results showed that: Betula platyphylla populations wereall aggregated distributions in the three habitats, Different types ofBetula platyphylla populations on the three slopes showedsignificantly aggregated distributions at relatively smaller scales andthe degree of aggregation decreased with increasing spatial scales，and it tended to uniform distributions at larger scales in the gentleslope; Seedlings had more obviously aggregated distribution andstronger aggregated intensity than the larger individuals; At relativelysmaller scales，there was a significantly positive association amongdifferent developmental stages in the three slopes．However，at largerscales either negative or uncorrelated association was foundbetween seedling and the other two stages, whereas positive oruncorrelated association was found between juvenile and matureplant. Among them pattern association among differentdevelopmental stages tended to negative association in the gentleslope．（3）In terms of the interspecific competition between the two(speciesPopulus davidiana and Butula platyphylla), no obviousrelationship was found when Butula platyphylla acted as themonodominant community, significant negative relationship wasidentified at the co-dominant stage, and no obvious relationship whenPopulus davidiana became the dominant species. The change ofrelationship between the two species was mainly driven by theintraspecific and interspecific competition for residual resources.This study indicates that the presently existing the form ofpolar-birch forest, being in the intermediate stage in the succession from the mixed forest of broad and needle-leaf trees to broad-leavedforest.