Studies On Structure And Interspecific Correlation Of Dominant Species Of Abies Fargesii Population In Shengnongjia Nature Reserve

Abies fargesii is endemic to China and its distribution center is located in Qinling-Bashan Mountains.Abies fargesii is distributed mainly on certain attitude that ranges from 2000m to 3104.5m in shennongjia nature reserve.We sampled trees in 30 plots(20m×20m),and,in each plot, we chose 5 grids(5m×5m) for shrubs,10 grids(1m×1m) for grasses,and 10 grids(1m×1m) for regeneration layer.The diameter at breast height(DBH) of each tree was recorded.Life history characteristics and spatial distribution of Abies fargesii population in Shennongjia National Nature Reserve was studied using the life table,age structure and survivorship curve of the Abies fargesii population in Shennongjia nature reserve to explain:1) population growth characteristics,and 2) how can biological and environmental factors affect population distribution and dynamics? In addition,The interspeefic correlation of dominant species of Abies fargesii population in Shennongjia Nature Reserve were analyzed by usingχ~2-test,Variance ratio(VR)test,Pearson's correlation coefficient and Spearman's rank correlation coefficient.The main results are as follows:1,Abies fargesii was the outstanding dominant species in the community,especially in the tree layer;its importance value reached 30.8%.Abies fargesii had significant influence on its structure,competition between all different kinds of plant,and regeneration.It suggested that Abies fargesii population was a developing population,as there were more seedlings and young trees than old trees.It was found that saplings were established more frequently in gaps than under the close canopy,which indicated a pattern of gap regeneration.2,The survivorship curve of Abies fargesii population generally matched a Deevey TypeⅠ, although seedlings were rare and have low survival rate due to high crown density.3,The spatial distribution in different growth periods is clumped or random.Populations tend to clump when interspecific competition is not severe in a wet and cold habitat in shennongjia nature reserve.Intraspecific competition also affects the clustering intensity of different growth periods.4,There were 49 dominant species such as Betula utilis,S orbus koehneana,Ribes longiracemosa by eliminating those plants that its frequency was less than 5%.The overall correlation of all species was positive and significant.In the other words,the results said that the dominant species have positive correlation and the Abies fargesii's community is stable.5,Compared with theχ~2-test,Pearson's correlation coefficient and Spearman's rank correlation coefficient,we can arrive at a conclusion that Spearman's rank correlation coefficient test is more sensitive.Whether plants did show significant association or not,Plant ecological characteristics is one of decisive factors.49 dominant species in the community of A bies fargesii led the population of Abies fargesii stable by using resources at best.