Comparison Of The Species Diversity And Phylogenetic Structure Of Tree Communities In Karst And Non-karst Mountains In Guangxi

We compiled data of 365 tree community plots from the literature,which are sampled across Guangxi and varied in plot area from 400 to 1000 m~2(with 50%in 400 m~2),and characterised species diversity and community phylogenetic diversity(PD)and structure,and their relationship with mean annual temperature(MAT)of the sampling location in three types of habitats such as non-karst with an elevations of≤1000 m,non-karst with an elevations of>1000m and karst with an elevations of<1000 m.We found that there are large differences in the composition of the three habitats between families,genera and species.Each habitat has its own special composition species.Among them,the non-karst forests with an elevation of≤1000 m contained more than 24 families and 18 families with 4 species than non-karst forests with an elevation of>1000 m and karst forests,respectively.Lauraceae,Fagaceae,Theaceae,Ericaceae are important and common families of non-karst forests at both low and high elevations.Euphorbiaceae has the largest species number in the karst habitat;and Theaceae and Ericaceae that appeared in the non-karst forests were absent in the karst forests.The species diversity and phylogenetic structure index(net relatedness index,NRI and nearest taxon index,NTI)of the tree communities in the three habitats were not significantly associated with the MAT.The phylogenetic diversity index of the non-karst forests with an elevation of<1000m was higher than that of non-karst forests with of either>1000m,indicating the former is favourable for hosting the more distant-related species.The Gleason’s diversity indices of karst and non-karst forests with an elevation of<1000 m were not significantly different,but significantly lower that of non-karst forests with an elevation of>1000 m.The phylogenetic net relatedness index(NRI)and the nearest taxon index(NTI)revealed that most of the forest communities in the three habitats showed phylogenetic clustering;and a small proportion of plots displayed phylogenetic overdispersion or random.It is speculated that habitat filtration plays a major role in the community assembly of karst and non-karst forests in Guangxi.The proportions of plots with phylogenetic overdispersion in the karst forests and non-karst forests with an elevation>1000m were lower than the non-karst forests with an elevation of≤1000 m,revealing that environmental filtration were stronger in the these two habitats.