Studies On Plant Diversity And Conservation In Tianjin Baxianshan Nature Reserve

Seed plant diversity and conservation were studied in Tianjin Baxianshan Nature Reserve. The object of this paper was to provide scientific methods and theories for plant diversity conservation of Banxianshan Nature Reserve. The following results have been obtained in this research:(1) The features and characteristics of the flora in Baxianshan Nature Reserve were analyzed. The results showed that there are 413 kinds of vascular plants (incl. 16 varieties) that belonged to 92 families and 270 genera in this area. The statistics of families showed that the family in which more species are included in the area is Compositae and Gramineae. And there are many few species family .The 82 families of seed plants can be grouped into 7 distributional types. The family belong to Pantropic type is on the top position, account for52. 46% of families. The 259 genera can be grouped into 15 distributional types as proposed by Wu Zhengyi. In the 15 types. North Temperate type, account for 37. 33% of genera, is on the top position, which showed the flora of the area have a strong North Temperate distribution feature.(2) The vegetation in Baxianshan Nature Reserve can be divided into 3 vegetation type groups, such as coniferous forest, broadleaf forest, thickets and herbaceous, 4 vegetation types, such as evergreen coniferous, deciduous broad-leaved, thickets, herbaceous; 27 formations, such as , Pinus tabulaeformis forest, Quercus variabilis forest, .Spiraea trilobata thickets, Vitex negundo var. heterophylla- Bidens pilosa herbaceous, Evodia rutaecarpa herbaceous, etc, and 58 association, such as Association Pinus tabulaeformis-Deutzia parviflora- Oplismenus undulatifolius, Association Quercus variabilis- Spiraea trilobata , Fraxinus chinensis Var. Rhynchophylla- Carex lancifolia, Association Fraxinus chinensis Var. Rhynchophylla, Deutzia parviflora.(3) The Diversity of pinus tabulaeformis community was studied in Tianjin Baxianshan Nature Reserve. A change of pinus tabulaeformis community richness was relevant to altitudinal. And the trend after increases reduces. The tree layers diversity was consistent with brushwood layers diversity change trend community diversity. The brushwood layers diversity and herbaceous layers diversity were richer than tree layers diversity. In different forest community, the tree layers, brushwood layers and herbaceous layers had obvious difference in species richness. Research show that order of richness in different communities from high to low was that herbaceous layers > brushwood layers > tree layers.(4) The quantitative assessment indices for endangerment categories and conservation priority grading of plant species of baxianshan Nature Reserve were established. The quantitative assessment indices included endangerment system, genetic loss system and useful value system. Endangerment coefficient described the endangerment category and conservation priorities coeficient described the preferential conservation of plant species. The results of assessment showed that the number of critically endangered species was 6, the number of endangered species 15, vulnerable species 39, near threatened species 43, Safe species 143. The number of the first concern species was 9, the second concern species 17, the third concern species 82, and the least concern species 138.