Pilot Study On Ecology Of Endangered Plant Sinojackia Rehderiana

Sinojackia rehderiana,also called Jiangxi counterpoise tree in taxonomy of Chinese trees,is a member of Sinojackia of Styracaceae.Its type specimen was collected in Wangcheng county of Nanchang in Jiangxi and it is listed as an endemic and endangered species distributed in subtropical regions of China.Currently the trees are distributed only in Yongxiu of Jiangxi,Huangmei of Hubei,Pengze of Jiangxi and Jingxian of Anhui.The characteristics of population age structure,spatial distribution pattern,species diversity of community,areal types of communities and interspecific association were studied in above 4 distributing area using the method of quadrat sampling.The purpose of the study is to find the mechanism causing S.rehderiana endangered and put forward corresponding conservation strategy.The result showed that:1.The existence of the populations of S.rehderiana in Yongxiu and Huangmei are in a good condition now,with 337 individuals for Yongxiu and 158 for Huangmei.The 2 populations are appearing a growth trend in the mass.However,the existence of the populations of S.rehderiana in Pengze is not optimistic.The number of individuals is rare(just 14 invisible)and the population showed no growth trend.For the population density and population viability,the above 3 populations showed that: Yongxiu>Huangmei>Pengze.2.There are 64,140,103 and 30 individuals for each sample in Yongxiu and 50,108 for each in Huangmei.The spatial distributions patterns of S.rehderiana population in Yongxiu and Huangmei showed the same pattern for different age stages.For populations with large number of individuals and good growth conditions,it showed random distribution pattern.For populations with a few individuals and bad growth conditions,it showed an aggregated pattern.3.In Yongxiu,the dominant species in the arbor layer,shrub layer and herb layer are Cinnamomum camphora,S.rehderiana and Ardisia japonica respectively in the community with S.rehderiana.In Huangmei,the dominant species in the arbor layer,shrub layer and herb layer are Quercus chenii,S.rehderiana and Ophiopogon japonicus respectively in the community with S.rehderiana.The species richness and species diversity are both high in the two communities.For the species richness,Yongxiu community > Huangmei community.There is no obvious correlation between species diversity and growth condition of S.rehderiana.4.There are 67,62,75 and 75 species for communities with S.rehderiana in Yongxiu,Huangmei,Pengze and Jingxian.The areal types of families and genera of communities with S.rehderiana in above 4 distributing areas are mainly tropic elements(with over 70% and 50% tropic elements for families and genera in all distributing areas),also with a certain proportion of temperate and Chinese endemic elements.The above 4 distributing areas are located in the area between the tropical zone and temperate zone.The similarity clustering analysis based on the discrepancy of species composition showed that the communities with S.rehderiana in Yongxiu,Huangmei and Pengze are clustered in one clade,while the community with S.rehderiana in Jingxian is clustered in another clade.5.In Yongxiu,the interspecific association between S.rehderiana and A.japonica is unknown.The interspecific associations between S.rehderiana and Alangium chinense,Diospyros oleifera,Smilax china is negative.The interspecific associations between S.rehderiana and A.crenata,C.bodinieri,Symplocos sumuntia,Gardenia jasminoides,Phyllanthus glaucus is positive.In Huangmei,the interspecific association between S.rehderiana and Mallotus japonicus,Q.chenii,Trachelospermum jasminoides,O.japonicus is mutual independence.The interspecific associations between S.rehderiana and Clerodendrum cyrtophyllum,Ilex cornuta,Q.serrata,Wisteria sinensis is negative.The interspecific association between S.rehderiana and Celtis sinensis is positive.From the interspecific association,the population viability in Yongxiu is stronger than that in Huangmei,which also can be shown in the amounts of individuals of each distributing area.