Study On Altitude Gradient Of The Plant Community Characteristics On The North Slope Of Highest Peak Of Daiyun Mountain

Using research means of community ecology and research methods of quantitative ecology,taking the plant communities on northern slope of Daiyun Mountain as research object,this paper studied on the characteristics of plant community and species diversity on northern slope of Daiyun Mountain. It studied species composition,community structure,quantitative characteristics,floristic characteristics,niche characteristics of main population,and species diversity of plant community on northern slope of Daiyun Mountain,so that can provide theoretical basis of comprehensive management of plant on Daiyun Mountain national nature reserve,the biodiversity protection,and forest management on subtropical area, and provide scientific basis of vertical pattern research of biodiversity on mid-subtropical mountain. The results were:(1)On northern slope of Daiyun Mountain national nature reserve,there are 60 families 118 genera 220 species of vascular plants,including 9 families 11 genera 13 species of pteridophyte,4 families 6 genera 7 species of gymnosperm,and 47 families 11 genera 13 species of angiosperm. And about the angiosperm,there are 43 families 90 genera 187 species of dicotyledon, 4 families 11 genera 13 species of monocotyledon.The floristic families are mostly Fagaceae、Lauraceae、Theaceae、Ericaceae、Aquifoliaceae、Rosaceae、Rubiaceae、Symplocaceae,etc.,and the plants of these families are main composing of vascular plants on northern slope.(2)In the types of distribution region on families of species on northern slope, the primary type is pantropic distribution(T2), the secondary type is worldwide distribution(T1). And the composition of temperate zone fauna(TW)is mainly with type of north temperate zone. In the types of distribution with genera about the species on the north slope,there are 11 genera 14 species of world wide distributed genera,and there are no significant regularity as the altitude increased,but the proportion of world wide distributed genera is rapidly increase when the altitude is up 1600 m. There are 58 families 126 species of the composition of tropical and subtropical fauna,and the proportion of it is reduced as the altitude increased. There are 44 families 75 species of the composition of temperate zone fauna,and the proportion of it is reduced integrally as the altitude increased.(3)As the result which is base on cluster analysis of the composition of flora shows:The plant communities on northern slope are classified into four types:Evergreen broad-leaved fores(taltitude is from 600 m to 1200 m),mixed wood(altitude is from 1300 m to 1400 m),temperate coniferous forest (altitude is 1500 m),mountain bush(altitude is from 1600 m to 1800 m).(4)The change of diameter structure of tree on northern slope was regular on all altitude gradient, the trends of diameter distribution were basically identical. The diameter distribution of tree on community type on all altitude gradient presented“L”shape basically.(5)The distribution trend of the individual number about tree height class in different altitude on northern slope is as follow:the individual number is reduced as the height class increased. Height class instability rate of dominant population in tree layer of community reflect the vegetation characteristics: the dominant population which have growth structure is changing into current pattern of community composition, the community is in the immature developing stage. The sharing of height class about tree in different altitude is reduced as the increasing of the height class.(6)The number of phaenerophyte in the community on northern slope of Daiyun Mountain is first, there are 182 specie(s82.73%),and the numbers of mesophanerophyte and microphanerophytes are mainly. The secondary is geophyte,there are 18 species (8.18%). The third is chamaephytes, there are 14 species (6.36%). The hemicryptophyte and annual plant is least, there are 3 species (1.36%) each. The species numbers of tree,shrub,evergreen plant,phaenerophyte are all reduced as the increasing of the altitude (P<0.05). The species numbers of chamaephytes and hemicryptophyte are positively correlated with altitude. The changing of species numbers of herb, deciduous plant and geophyte are not significant as the change of altitude.(7)The niche of Schima superba is largest in the tree layer,and the secondary are Itea oblonga、Cunninghamia lanceolata、Rhododendron latoucheae, the least are Pinus taiwanensis and Castanopsis carlesii. The niche of Adinandra millettii is largest in the main species of shrub layer,and the secondary are Eurya rubiginosa var. attenuata、Vaccinium carlesii、Vaccinium carlesii、Eurya loquaiana、Bredia sinensis、Itea oblonga,etc. The least are Castanopsis eyrei、Rhododendron rivulare、Maesa japonica、Sinobambusa tootsik. There are 54 pairs niche overlapping species in tree layer,which are 81.81% of all species pairs. The niche overlap is general in main species of tree layer,it reflect that the space resource of tree layer is finite,there are lots of species of tree,and the modes of using resource are uniform. The niche overlap is less in main species of shrub layer, it shows that they can make full use the understory space and resource,and grow in the relatively independent niche.(8)The change trend of the species richness index, Shannon-Wiener index, and Simpson index of vascular species on the northern slope of Daiyun Mountain are basically identical,which all are increased at first and then decrease,and increase then decrease again,as the altitude increase. The regularity of Pielou index is not significant as the altitude increase. The change trend of Sorensen index,Jaccard index and community dissimilarity index are basically identical,which all are wavy fluctuation in the research region as the altitude increase. The Cody index is decreased as the altitude increase,it reflect that the difference of community is smaller as the altitude increase,and the community species richness is decrease, the less species leading to lower rates of species changing.(9)The change of the species diversity of plant community as the altitude gradient changing on southern and northern slope of Daiyun Mountain were researched by comparing both slopes,the results showed that:the species richness present different distribution patterns between southern and northern slope along the altitude gradient; the species richness on southern slope present single peak distribution pattern as the altitude increased; the species richness on northern slope present double peak distribution pattern as the altitude increased; theαdiversity index andβdiversity index both present different distribution pattern on southern and northern slope.