Forest Community Structure And Species Diversity In Qingyunshan Natural Reserve,Guangdong

Guangdong Qingyunshan Nature Reserve locates at the subtropical monsoon climate zone and has typical and complete evergreen broad-leaved forest ecosystem.It is a typical site for the research in the subtropical forest ecosystems and has important protection values.A series of forest dynamic plots with a total area of 2.24 hm~2 were set up in Qingyunshan Nature Reserve.Based on the survey data,the species composition,floristic components,community structure,species distribution,relationship between species distribution and environmental factors were analyzed.The main results are listed as follows:(1)There were a total of 13630 stems with diameter at the breast height(DBH)?1cm,belonging to 52 families,110 genera and 216 species in plot.The proportionsof rare and occasionalspecies of all species were 20.7%and 37.6%,respectively.The dominant species were Cunninghamia lanceolata,Schima superba,Diospyros morrisiana,Rhododendron moulmainense,Castanopsis fissa,Castanopsis fargesii,Castanopsis faberi,Castanopsis carlesii,Machilus chinensis,Itea chinensis,Phyllostachys edulis and Castanopsis eyrei.Fagaceae,Lauraceae,Theaceae,Gramineae,Taxodiaceae,Ericaceae,Ebenaceae,Aquifoliaceae,Elaeocarpaceae and Euphorbiaceae were dominant families.(2)These 52 families of 216 woody plants can be classified into nine flora distribution types.Tropical flora type accounts for 80.95%,while temperate type accounts for 19.05%of all flora types in the family.The 110 genera can be classified into 12 flora distribution types.Tropical flora type accounts for 70.64%,while temperate flora type accounts for26.61%of all flora types in the genera.The flora was characterized by the transition from subtropical to tropical.(3)Diameter distribution of all individual plants in plot showed inverted J-shaped structure,with plant species rich in small diameter.The number of recorded species gradually decreased with the increase of diameter at breast height.The regeneration of community shows a stable pattern.Among the dominant species,Cunninghamia lanceolata,Schima superba,Diospyros morrisiana,Castanopsis faberi,Castanopsis fargesii,Rhododendron moulmainense and Machilus chinensis populations show increase pattern,while Castanopsis fissa,Phyllostachys edulis and Castanopsis eyrei populations show decrease pattern.Castanopsis carlesii population suffered some damage,while Itea chinensis population lacks medium and large diameter individuals.All dominant species showed aggregated distribution pattern.(4)The ecological niche width of the dominant species is aligned from large to small:Diospyros morrisiana,Castanopsis fargesii,Schima superba,Itea chinensis,Castanopsis faberi,Rhododendron moulmainense,Castanopsis carlesii,Castanopsis eyrei,Machilus chinensis,Castanopsis fissa,Cunninghamia lanceolata and Phyllostachys edulis.There was a low degree of niche overlap and niche similarity among species within the community,and their interspecific competition was not intense.Among the dominant species,Schima superba,Diospyros morrisiana,Rhododendron moulmainense,Castanopsis fargesii,Castanopsis faberi and Itea chinensis were at increasing stage while Cunninghamia lanceolata,Castanopsis fissa,Castanopsis carlesii,Machilus chinensis,Phyllostachys edulis and Castanopsis eyrei were at decreasing stage.Linear regression analysis showed that there was no obvious correlation between niche width and importance values,while the niche breadth was negatively correlated with the variance of importance values.(5)The 14 plots of the Qingyunshan nature reserve can be classified into five community types,including Castanopsis fissa+Castanopsis carlesii community(?),Pleioblastus amarus+Cryptocarya chingii community(?),Rhododendron kwangtungense+Lithocarpus naiadarum community(?),Schima superba+Rhododendron moulmainense community(?),and Cunninghamia lanceolata+Phyllostachys edulis community(?).The species diversity of the community was relatively high with the Margalef index of23.36,Shannon-Wiener index of 4.10,the Simpson index of 0.97 and the evenness index of0.76.In total,species diversity was high but species distribution was uneven.The result ofspecies diversity in different forest communities showed that the species richness index decreasedin the following sequence:community?,community?,community?,community?,community?,but the species diversityindices and evenness indices varied as follows:community?,community?,community?,community?,community?.(6)Environmental factors had a significant effect on the species distributionin Qingyunshan Nature Reserve.The elevation,pH,total calcium,cation exchange capacity and mass water content are the most important environmental factors affecting the species distribution.