Altitudinal Patterns Of Plant Diversity On Niubeiliang Nature Reserve, Qinling Mountains

Mountain areas tend to concentrate natural geographical features and bio-geographical characteristics thus being an ideal place for develop and validate biological diversity, because of the high heterogeneity of habitats and relatively low human disturbance, more to become a haven for a large number of species and cradle of new flora's differentiation in geological history, is the world's key regions of biological diversity.As geography and climate of the dividing line for China south and north, also the watershed of two major river systems: Yangtze River and Yellow River, Qinling Mountain has large height difference in terrain and complicated topography; there is survival environment for many kinds of species. Niu Beiliang Nature Reserve located in east of Qinling Mountain, crossed south to north, long-narrow distribution along east to west. Under the influence of warm and semi-humid climate, formed a complete vertical belt of vegetation, the vertical differentiation of the flora, species diversity of community composition and the type of community structure in the Qinling region has some of the typical and representative.This research investigate plant resources and typical communities from June 2008 to September 2009, on this basis, quantitative analysis composition of floristic, altitudinal gradient pattern, variation of species diversity along altitude gradient in different community layer and numerical classification of community. Results show that:(1) There are 1011 seed plants in Niubeiliang Nature Reserve, belonging to 106 families and 449 genus, it is the important component of seed plant flora in Qinling Mountain(2) Seed plant flora of Niubeiliang Nature Reserve is obviously of temperate nature, there is no floristic equilibrium point. But reflected historical connection with tropical flora, 1500m above sea level is the limit distribution of most tropical elements. In all flora components, proportions of components connected with arid surroundings are low; indicating that geographical environment of Reserve is humid in history. Sino-Himalaya genera of East Asia raised obviously along elevation, because of Himalayan movement occurred at the end of Tertiary create conditions for Sino-Himalaya genera towards southeast spread along medium high mountain.(3) Results of clustering analysis shows that, vegetation along an altitudinal gradient of protected areas can be divided into five bands: deciduous broad-leaved forest belts in middle-low mountain, elevation from 1000 to 2000m; deciduous broad-leaved forest belts in middle mountain, elevation from 2000 to 2500m; subalpine cold-temperate coniferous forest belts, elevation from 2500 to 2600m; subalpine shrub belts, elevation from 2600 to 2800m; subalpine meadow vegetation belts, elevation from 2800 to 2900m. There is accordance between clustering analysis and traditional division method of traditional method.(4) Communities species diversity index along altitudinal gradient showed the same trend, that is, with the elevation gradient were first increased and then decreased, indicating the total species of this region obtained maximum in moderate-altitude, so it is the typical"mid-altitude bulge".(5) Numerical classification of community was performed by using TWINSPAN, plant communities were divided into 8 vegetation types and 20 associations, 8 vegetation types including Deciduous broadleaved forest, Deciduous-evergreen broadleaved mixed forest, Temperate coniferous broadleaved mixed forest, Temperate coniferous forest, Cool-temperate coniferous forest, Deciduous broadleaved shrubs, Evergreen leather-leaf shrubs and Subalpine meadow.