Effects Of Community Succession On Population Of Sinomanglietia Glauca,an Endangered Plant Endemic To China

Sinomanglietia glauca,a rare deciduous plant in Magnoliaceae,is a uniquely rare and endangered species in China.Combined with previous field investigations and research,we found that the communities of S.glauca are undergoing positive succession combined with bamboo expansion in Yi Chun city.However,The prosperity of evergreen trees and bamboos may threat the growth and survival of S.glauca through changing community environment,and eventually even accelerate its endangered pace.Therefore,it is necessary to study the influence of evergreen tree species on wild S.glauca.We selected habitats of different dominance level of trees species and performed an experiment on comparing S.glauca population structure and dynamic structure in the habitats in Mingyueshan Mountain,Yichun province.And we studied the intraspecific and interspecific competition and discussed the growth and morphological characteristics of S.glauca in the habitats from the perspective of individualism and component.By comparing the growth of S.glauca in different habitats and analyzing the influences of evergreen tree species.We hope our research would provide a theoretical reference for S.glauca conversation..The results were as follows:(1)Under different backgrounds,the population of S.glauca has some differences.After experiencing the age class of the next 2,4 and 6,the populations of evergreen-deciduous mixed forests and evergreen broad-leaved forests decreased by 7.6%,42.0%,63.7% and 12.4%,51.8% and 68.3%,respectively.(2)In terms of the overall two habitats,the pressure on S.glauca mainly is the interspecific competition.The intraspecific competition intensity of S.glauca was 900.73,which was 40.5% of the total competition intensity,and the interspecific competition intensity was 1321.96,accountinged for 59.5% of the total competition intensity.(3)There is a big difference in the competition situation of S.glauca population in different succession stages.The intraspecific and interspecific competition pressures of the mixed forest are nearly equal,while the majority of the competitive pressure in the evergreen broad-leaved forest comes from its accompanying tree species,and the interspecific competition index accounts for 74% of the total competition of the community.The mean and interspecific competition pressure of S.glauca in evergreen broad-leaved forest is greater than that of evergreen broad-leaved forest,and most of the interspecific competition pressure in both communities comes from evergreen tree species.(4)There were significant differences in S.glauca DBH growth between the two communities.The growth increment of DBH of is 6.63mm-7.64mm/a in habtat1 and that in evergreen broad-leaved forest is 3.62mm-4.03mm/a.(5)There was a significant negative correlation between the intensity of competition between neighboring trees and the growth of DBH in S.glauca.(6)In different succession stages,the DBH growth increment of S.glauca in different age groups during the first three years of is quite different.During the first three years of growth in evergreen-deciduous mixed forests,there was almost no difference in the growth of DBH between different age groups.However,in evergreen broad-leaved forests,there is a certain difference in the DBH growth between different age groups of S.glauca during the same growth period.The DBH growth of S.glauca,more than 30 years in the first three years was significantly higher than that in the other two age groups,and it was close to the average growth of evergreen-deciduous mixed forests.(7)There was significant differences in the growth of saplings in the different succession stages.The average stem high growth,average branch growth,and the number of new leaves of shoots were significantly higher in mixed forest than that in evergreen broad-leaved forests.All in all,changes of forest stand caused by community succession has a negative influence on S.glauca.on the levels of community,population,and individualism If we continue to maintain the current protection strategies and blindly endeavor to forestry protection,then rare and endangered population of Yi chun S.glauca,they may be submerged in the wave of history in the near future.Therefore,it is necessary to adopt artificial community adjustments to purposely improve the environment of endangered species,thereby increasing the suitable habitat in order to better protect them.At the same time,this also provides a basis and reference for the protection and research of other endangered plants.