Studies On Community Structure And Succession In Montane Mixed Evergreen And Deciduous Broadleaved Forests Of Xingdoushan Nature Reserve.Hubei Province

Mixed evergreen-deciduous broad-leaved forest is main body of subtropicalmountain which plays an important role in ecological functions. Mixed Evergreenand Deciduous Broadleaved Forests in XingdouShan Nature Reserve is the type offorest vegetation typical. This paper discusses the community type,speciescomposition, community structure, biodiversity, niche and community succession onMixed Evergreen and Deciduous Broadleaved Forests in XingdouShan NatureReserve, The results are as follows:1Through Hierarchical Clustering analysis and Non-Metric MultidimensionalScaling （NMS）ordination., mixed evergreen and deciduous broadleaved forest inXingdoushan can be divided into three different community types:①Comm. Sorbusalnifolia+Cornus controversa+Betula luminifera which located in the lower part ofthe mountain;②Comm. Sorbus alnifolia+Lithocarpus cleistocarpus which locatedin the middle of mountain;③Comm. Fagus lucida+Cyclobalanopsis multinerviswhich located in the upper part of the mountain.2The species composition of vegetation are complexed for Xingdoushanevergreen-deciduous broad-leaved mixed forest, and there are53families,105genera and225species which including101kinds of deciduous trees,79kinds ofevergreen trees,25kinds of deciduous shrubs and20kinds of evergreen shrubs.where: there are42families,76genera and141species woody plants in Comm.Sorbus alnifolia+Cornus controversa+Betula luminifera;52families,89genera and142species woody plants in Comm. Sorbus alnifolia+Lithocarpus cleistocarpus and43families,80genera and122species woody plants in Comm. Fagus lucida+Cyclobalanopsis multinervis. Billing division, single genus and single speciesplants belongs to the most in the species composition of different community types.3Through the analysis of Stand density(stemden.), Basal area(ba.), number ofspecies (spnum.), Margalef richness index(rarefy100. R), Shannon—wiener index(shannon. H), Simpson index (Simpson. D) and Pielou evenness index（evenness. JH）, it shows that:①The communities located in the middle of mountain havehighest stand density, which is453strains/400m2, and the stand densities ofcommunities located in the lower and upper parts of mountain are309strains/400m2and304strains/400m2respectively;②The basal area of community presentsincreasing trend with the increase of mountain altitude, and this trend may be relatedto anthropogenic interference;③Margalef richness index is the largest forpolydominant Comm. Sorbus alnifolia+Cornus controversa+Betula luminifera, whichis26.66, while the Margalef richness indexes of polydominant Comm. Sorbusalnifolia+Lithocarpus cleistocarpus.and Comm. Fagus lucida+Cyclobalanopsismultinervis are fair, which are23.01and23.05respectively;④The three differenttypes of communities features reflected by Shannon-wiener index, Simpsion indexand Pielou evenness have preferable consistency, which present decreasing trendwith the increase of altitude;⑤The biodiversity indicator (except evenness) ofarborous layer of Xingdoushan evergreen and deciduous broad-leaved mixed forestis much higher than that of the shrub layer.4The community structures of different types of communities for Xingdoushanevergreen-deciduous broad-leaved mixed forest exist difference:①Through theanalysis of community age structure (diameter class structure), it shows that thepolydominant communities located in the middle and lower parts of the mountain arein development stage, while the communities located in the upper part of themountain are in stable mature stage;②Through the analysis of vertical structure ofcommunity, it shows that upward along the mountain, the individuals continue togrow and mature within a community will be more rational use of resources on theground;③Through the analysis of dominance and functional groups for majorspecies of different types of communities, it shows that the composition ofpolydominant species for various communities is complex; the number of dominantspecies for the arborous layer presents decreasing trend with the increase of themountain altitude, among which the proportion of deciduous component decreases,while the proportion of evergreen component gradually increases.5The dominant populations of different communities for Xingdoushan evergreen-deciduous broad-leaved mixed forest occupy their own unique spacialecological niche in the communities. Through the analysis of ecological niche breadth,find that different types of communities dominant species will constitute differentguilds on the resources axis of vertical and horizontal spaces, which presentspolynomial nonlinear distribution in the vertical and horizontal two-dimensionalspatial ecological niche distribution pattern; through the analysis of ecological nicheoverlap, find that different types of communities dominant species have higherresources pressure in the competition vertical and horizontal spaces; the ecologicalniche overlap (Np) is high, and the average ecological niche overlap Np of variouscommunities dominant species presents increasing trend with the increase ofaltitude.6Through the analysis and deduction of contribution rate to various stand classesof different types of communities dominant species, it shows that the overallsuccession trend of developing polydominant Comm. Sorbus alnifolia+Cornuscontroversa+Betula luminifera will evolve in the direction Comm. Daphniphyllummacropodum+Cornus alnifolia+Carpinus turczaninowii; the overall succession trend ofpolydominant Comm. Sorbus alnifolia+Lithocarpus cleistocarpus will evolve in thedirection polydominant Comm. Sorbus alnifolia+Sorbus folgneri+Daphniphyllummacropodum, while the more mature Comm. Fagus lucida+Cyclobalanopsis multinervishas basically completed the community succession process.