Community Structure, Population Structure And Dynamics Of Chinese Pine (Pinus Tabuliformis) Distributed On Ridge In The Middle Of Qinling Mountains

Chinese Pine(Pinus tabuliformis) is an endemic species in China. It is one of the main tree species in Qinling Mountains. To investigate the population of Chinese pine, 16 sample plots were selected and established in the middle of Qinling Mountains. And then we studied Chinese pine forests distributed on ridge in terms of four aspects: the structure and natural regeneration of community, the spatial distribution and structure of population and interspecies and intraspecies competition.The main research conclusions are as follewed:(1) There are 70 species in Chinese pine forests and they belong to 35 families and 54 genus. Most of them are belong to Rosaceae, Compositae, Poaceae, Liliaceae, Pinaceae and Caprifoliaceae. There are 22 species in tree layer. Pinus tabuliformis is dominant tree species and Pinus armandii, Quercus aliena var.accuteserrata, Quercus spinosa and Tsuga chinensis are subdominant tree species. There are 25 species in shrub layer and Smilax chinal, Rhododendron micranthum, Rhododendron lapponicum, Fargesia spathacea, Rosa tsinglingensis, Abelia dielsii, Euonymu salatus, Cotoneaster multiflorus and Deutzia scabra are main species. There are 23 species in herbaceous layer and Carex rigescens, Carex Siderosticta, Primula cinerascens, Carex lanceolata, Phlomis umbrosa and Saussurea dutaillyana are main species. The coverage of different layers was tree layer=shrub layer> herbaceous layer.(2) The study of natural regeneration of Chinese pine forest showed that species composition of seedling and sapling are relatively simple and the importance value of different species changed intensively from seedling stage to sapling stage. Because of the environmental condition of ridge, the sapling of Chinese pine is dominated which is quite different to the sapling of oak species.(3) The study of the relationship between seedling and sapling composition and environmental factors showed that the CCA ordination analysis of 14 explanatory variables explained 94.32% of the variation of seedling species data and 92.48% of the variation of sapling species data, respectively. Available N, available K, elevation and soil water conent are main factors that influence the distribution of seedling, while elevation and stone coverage are main factors that influence the distribution of sapling.(4) The study of age structure and dynamic of Chinese pine population distributed on ridge showed that the young and middle-aged individuals were abundant in the population, while the number of old individuals were relatively low. The age structure of Chinese pine showed a reversed-J-shaped distribution which means the population was in growth state. However, the quantitive analyse of population structure showed that the increase of population was not evident which keeps the polulation in a stable stage.(5) The study of spatial distribuion pattern of Chinese pine distributed on ridge showed that the distribution of population is clumped pattern in different block size as well as different age groups. The biological characteristics of Chinese pine, canopy density and environmental heterogeneity might be contribute to this result.(6) The study of interspecies and intraspecies competition of Chinese pine population distributed on ridge showed that the intraspecies competition is far more intensive than interspecies competition and Pinus armandii, Quercus spinosa and Quercus aliena var.accuteserrata are main tree species that contribute to the interspecies competition. In addition, the competition intensity are decreased as the increasing of diameter of target trees.In general, the species composition of Chinese pine forest distributed on ridge is relatively simple and the community naturally regenerated itself. The population was in growth state, however, the increase of population was not evident which keeps the polulation in a relatively stable stage. The distribution of population is clumped pattern. The intraspecies competition is far more intensive than interspecies competition and Pinus armandii, Quercus spinosa and Quercus aliena var.accuteserrata are main tree species that contribute to the interspecies competition.