Patterns Of Plant Community And Biodiversity On South Slope In The Middle Of Qinling Mountains

Plant community and species diversity on south slope in the middle of QinlingMountains were studied comprehensively. Qinling Huoditang, Niubeiliang Nature Reserveand Tianhuashan Nature Reserve were selected as research region. Based on the line transectmethod,108standard plots were investigated in the field. Flora characteristics, quantitativeclassification and ordination of plant communities, plant species diversity, the elevationalpatterns of plant species diversity, and the relationship between plant species diversity andsoil enviroment were examined using statistics, quantitative ecology and analysised. Theresults are as follows:There are1238species belonging to136families and547genera in Huoditang. In thosespecies, the biger families and biger genera plays important roles; the geographical elementsof the flora are comparatively complex, and the genera of temperate are the dominant arealtypes (335genera, account for61.2%); the genera of tropics and subtropics, world distributionand speciality distribution in China account for24.7%,10.42%and3.66%respectively.Through clustering analysis and PCA ordination,8regions were divided into4groups.The first group includes Huoditang, Tianhuanshan, and Qingmuchuan. The second groupincludes Niubeiliang and Laoxiancheng. The third group includes Funiushan. The fourthgroup includes Xiaolongshan and Ziwuliang. It is obvious difference in different regions. Thefloristic variation with longitude in Qinling Mountains are that: the compositions of northtemperate and temperate zone distribution increase with dropping of longitude, thecompositions of tropics and subtropics zone distribution increase with rising of longitude. Thetransitionality in Funiushan is stronger than the other regions.The field approach underlying a vegetation study influences the results of biodiversityassessments. we compared two main field survey approaches for forest vegetation recording,the Chinese and the European ("phytosociological") one, for their differences andefficiency when applied to plant communities of temperate forests. The Chinese approachuses a design with different plot sizes for recording the tree, shrub and herb layer species,respectively, while the European one uses the same plot size for recording all layers andspecies. The two approaches result in significant differences on species richness, Simpson'sdiversity index, and Shannon-Wiener index, while evenness index is not different. The European approach has the ability to survey the number of different species more preciselythan the Chinese one. For detecting the general patterns of diversity, however, the twoapproaches have the same ability, demonstrated here for the altitudinal gradient.Plant communities were classified into33formations by Two-way Indicators SpeciesAnalysis (TWINSPAN) combined the book "Chinese vegetation". They are Form. Larixchinensis, Form. Larix principis-rupprechtii (cultural forest), Form. Abies fargesii, Form. A.chensiensis, Form. Picea. wilsonii, Form. Pinus armandii, Form. Pinus tabulaeformis, Form.Pinus tabulaeformis+Pinus armandii, Form. Pinus armandii+Quercus, Form. Pinusarmandii+Tilia, Form. Pinus armandii+Betula albo-sinensis, Form. Pinus armandii+Toxicodendron vernicifluum, Form. Pinus tabulaeformis+Quercus aliena var., Form.Quercus variabilis, Form. Quercus aliena var., Form. Castanea mollissima, Form. Ulmuspumila, Form. Betula platyphylla, Form. Betula albo-sinensis, Form. Betula albo-sinensis var.septentrionalis, Form. Quercus aliena var.+Carpinus turczaninowii, Form. Quercus variabilis+Carya cathayensis, Form. Sinarundina nitida, Form. Bashania fargesii, Form.Rhododendron capitatum, Form. Dasifora glabra-Carex+Spiraea alpina, Form. Salix, Form.Berberis, Form. schisandra sphenanthera, Form. Carex schneideri, Form. Deyeuxia sylvatica,Form. Clinelymus nutans, and Form. Carex luctuosa. These communities belong to4Vegetation Type Group,7Vegetation Types,14Vegetation Sub-Types. Results of ordinationby Detrended Correspondence Analysis (DCA) shows that the change of elevation and waterinfluence the distribution of plant communities.The diversity index on South Slope in the middle of Qinling Mountains minished inorder: temperate coniferous forest, cool-temperate coniferous forest, deciduous broad-leavedforest, deciduous broad-leaved shrubs, meadow, temperate bamboo forest and leatherleaf; inthe different layers, the diversity index in herb layer is higher than that in shrub layer and treelayer. In herb layer, the highest diversity is in deciduous broad-leaved shrubs, the lowest is intemperate bamboo forest. In shrub layer, the highest diversity is in temperate coniferous forest,the lowest is in leatherleaf. The most abundant of tree specise is temperate coniferous forest.Among the12forest community types, plant diversity in the herb layer is the highest,followed by that in the shrub layer and in the tree layer. Form. Picea wilsonii has a meannumber of plant species about40, followed by Form. Pinus armandii and Form. Abies fargesii,Form. Quercus variabilis only has21. Plant diversity of tree layer is the highest in the Form.Betula platyphylla, followed by Form. Pinus armandii, Form. Quercus aliena var.acuteserrata. Plant diversity of shrub layer is higher in Form. Picea wilsonii, Form. Pinusarmandii, Form. Quercus aliena var. acuteserrata, Form. Abies fargesii, and Form. Pinustabulaeformis than in other forms. Plant diversity of herb layer is the highest in Form. Betula albo-sinensis var. septentrionalis, followed by Form. Picea wilsonii and Form. Pinusarmandii. The Simpson's diversity index and Shannon-Wiener index of herb layer issignificant positive correlation with that of tree layer, but no related with shrub layer. Amongshrub communities, plant diversity in herb layer is obvious higher than that in shrub layer. Thespecise richness is highest in Form. Dasifora glabra-Carex+Spiraea alpina, followed byForm. Salix, Form. Rhododendron capitatum and Form. Berberis.The α diversity (species richness, Simpson index, Shannon-Wiener index and evenness)showed single peak curve with the elevation gradient between1000m~2868m. The speciesrichness, Simpson index and Shannon-Wiener index of herb layer increased with theincreased altitude, stabilized at altitude of1500m, then increased from altitude of2300m;the species richness, Simpson index and Shannon-Wiener index of shrub layer and tree layerincreased with the increased altitude, then diclined from the altitude of1700m; the evennessof shrub layer and tree layer has no change with the change of elevation. Whittaker index wasfluctuate at the atitude from1000m to1500m and from2500m to2800m, and decreasedwith increased altitude, then increased. Wilson index showed single peak curve with increasedaltitude. With increased altitude gap, Jaccard similarity index became smaller. Bray-Curtisindex showed the similar trend with Jaccard similarity index.There were close correlations between elevation and pH value, soil organic matter, totalnitrogen, available phosphoru. And there was no correlation between elevation and availablenitrogen, total phosphoru, available potassium. With the increase of elevation, pH valueincreased, the highest value was at the altitude of1800m~2000m, then decreased. The soilorganic matter and tatal nitrogen incresed with the increase of elevation, but soil availablephosphorus decreased. Based on principle components analysis, the value of soil nutrient inorder were: Betula albo-sinensis forest, Quercus aliena var.acuteserrata forest, pine-oakforest, Pinus armandii forest, Picea wilsonii forest, Quercus variabilis forest, Abies fargesiiforest, and Pinus tabulaeformis forest. There has a correlationship between species diversityand pH value,soil organic matter. The DCCA showed that species diversity was positivecorrelative to available potassium, and negative correlation with available nitrogen.