Pattern Of Phylogenetic Diversity Of Karst Forest In Maolan And Its Influencing Factors

Karst forests are rich in biodversities,but the assembly mechanisms of these forests are still poorly konwn.Maolan National Nature Reserve,which locates in south Guizhou,preserves a large piece of karst forests.The complex terrain within the reserve creates various habitats that harbor large number of plants.Here,in the Maolan Reserve,through the establishment of forest plots at the hilltop and slope in six peak-clusters widely distributed in the reserve,I investigated the taxonomic and phylogeneticαandβdiversities patterns of the karst forests,as well as their driving factors,to infer the community assmbly mechanisms of the karst forests.I conducted statistical analyses,such as linear mixed-effects models and the multiple regression method of Mantel test,The results are as follows:1.The studied karst forests are rich in biodiversity.In the 12 forest plots with total area fo 5400 m~2,there were 2395 woody plant individuals with diameter at breast height≥1cm that belongs to 200 species,129genera and 64 families.2.Taxonomicαdiversities,e.g.species richness and Shannon-Wiener index,were not different between hilltop and slope habitat,but within habitatβdiversity differed between hilltop and slope habitats.Taxonomicαdiversities were affected by elevation,habitat type,soil P and soil p H;taxonomicβdiversity was affected by habitat type and rock coverage.Spatial factor,i.e.geographical distance,showed no influence on taxonomicβdiversity.3.Phylogeneicαdiversities differed between hilltop and slope habitat.Hilltops were with more clustered dispersions of NRI and NTI than the slopes,indicating stronger environmental filtering.The slopes were with NRI and NTI that centered around 0,indicating a weak filtering influence.The phylogeneticβdiversities,i.e.,βNRI andβNTI,also differed between hilltop and slope.Hilltops were more similar in phylogenetic composition compared with slopes,also indicating a larger role of environmental filtering on hilltops.On th other hand,no significant driving factors,includiing environmental and spatial factors,were detected for phylogeneticβdiversities.The findings suggest a significant role of environmental filtering in shaping the assembly of the Maolan karst forests,and a lack of evidence of the influence of neutral mechanisms such as dispersal limitation.This study helps to further our understandings of the karst forest assembly mechanisms.