The Shrub Diversity And Leaf Functional Traits Of Rhododendron Latoucheae Communities To Altitude In Mt.Jinggangshan,Jiangxi,China

Researching on the spatial variation of community diversity and leaf functional traits along altitudinal gradients can enhance our understanding of the maintenance mechanisms on diversity and ecosystem function.In this study,shrubs in Rhododendron latoucheae communities distributed along an altitudinal gradient in Jinggang Mountain,Jiangxi were choosed as the research objects.The plant diversity and species composition in shrub layer of the R.latoucheae communities were classified and identified by means of field investigation.Based on the survey data,we calculated the Speciese richness,Shannon index,Pielou index and Simpson index,functional volume(FRic),functional evenness(FEve),quadratic entropy(Rao),functional evenness(FEve)and functional dispersion(FDis).Leaf functional traits including the dry matter content(LDMC),specific leaf area(SLA),thickness(LT),leaf size(LS),nitrogen(LNC),phosphorus concentration(LPC)and N/P reduced were measured in different altitude gradient communities.The relationship between species diversity,functional diversity,leaf functional traits and environmental factors were analyzed.Meanwhile,we explored the relationship between species diversity and functional diversity,and the internal relationship between leaf functional traits.Results revealed the responsetendency of the community diversity and leaf functional traits in shrub layer to environmental changes,which could provided scientific basis for the conservation and management of the community resources and biodiversity of R.latoucheae communities in Jinggang Mountains.The results showed that:(1)A total of 68 species of plants were recorded in studied area,belonging to 30 families and 47 genera.,including 3 family,4 genera and 5 species of gymnosperms plants,1 family of monotyledonous(Dioscoreaceae)and 26 families of dicotyledonous.(2)Species diversity index showed a consistent trend along the altitudinal gradient.The Speciese richness,Shannon index,Pielou index and Simpson index decreased with increasing altitude.And they are mainly affected by elevation.The Speciese richness,Shannon index could also be influenced by soil N content,while Simpson index was affected by soil P concentration.(3)Functional diversity index presented a complex variation trend with the elevation gradient.Altitude was significant negatively related to FRic,FEve and FDis,but positively correlated with FDiv and Rao.FRic,FEve,Rao,FDis and FDiv were strongly associated with elevation,and FEve also affected by slope position.In addition,soil P content was significantly correlated to FRic,Rao and FDiv.Soil N concentration had influenced on FDis.(4)There was a complicated correlation between species diversity and functional diversity of communities.FRic was positively correlated with the Speciese richness and Simpson index,and has the best fitting logarithmic equation with the Speciese richness;FEve had a strong logarithmic function relationship with the Speciese richness;Rao had a linear negative correlation with Pielou index and Simpson index;FDis was positively correlated with the Shannon index and Simpson index,and had the strongest logarithmic function relationship with the Speciese richness.FDiv was negatively correlated with Shannon index,Pielou index and Simpson index.The relationships between species diversity and functional diversity of shrubs in R.latoucheae communities and their response to environmental changes determined the community ecosystem function collectively.(5)The dry matter content(LDMC),thickness(LT),nitrogen(LNC)and phosphorus concentration(LPC)of leaves increased with altitude rising,whereas the specific leaf area(SLA)and N/P reduced.With the increasing elevation,the leaf size(LS)increased at first and then decreased.Besides,slope also affected SLA,LPC and N/P.Furthermore,LS and LNC were influenced by slope aspect and gradient.(6)In general,inherent correlations were observed among leaf functional traits of shrub.LDMC was negative related to SLA and LS,but positive correlated with LT,LNC and LPC.whereas the relationship between SLA and LT,SLA and LNC,LS and LT,N/P and LPC was negative,respectively.Therefore,plants in shrub layer of the R.latoucheae communities adapted to changes in altitude and environmental factors by altering the Leaf functional traits.