| Larix Chinensis Beissn, which is endemice species, only distributes the zone from 2600 to 3500m altitude in Mt. Qinling, Shaanxi Province of China. This thesis mainly deals with Larix Chinensis in two aspects. One is macrocosmic ecology about the diversity of the population, the community and the landscape, and the other is the molecular ecology about the genetic diversity analysis of intrapopulations and interpopulations, with special emphasis on the cause of endangered state and conservation strategy of the species.1 The diversity of the population In Mt. Qinling 4 sampling stands were set up at Mts. Taibai, Guangtou, Yuhuangshan and bingjingding respectively. 280 plots in Larix chinensis population were investigated by the sampling method. The community feature, size-class structure, the regulation of changing density were analyzed, as well as worked out the survivorship curve, the death curve and the life table. The results indicated the populations had one peak of mortality between 25-30cm, and the survivorship curve trended to be the type between DeeveyII and III. The large size-class populations were stability and variable in small size-class population. The restricting factor for the survival and development of the population was a short seedling.2 The community diversity Based on the above plot data, Larix chinensis community characteristics were analyzed about the specific composition; the flora feature; the community physiognomy; the vertical and level structure; and the regulation of environment. The indexes of the frequency and the coverage and the species diversity (Shannon-Wiener index; Simpson index; Pielou index and Probility of Interspecies Encounter index) were measured in L. chinensis community in the sampling stands. The results were followed: (1) the community of L. chinensis apparently distributed to high-altitude montane at 2800-3500M in Qinling ranges; (2) the specific composition of the community is about 84 species, which the genus of the boreal temperate zone is absolute dominance. The species and quantity of hemicryptophyte were both more and larger. There was a striking dominant synusia of L. Chinensis in the L. chinensis community, which was a monodominant community. The H index of tree layer was 0.207-0.420, brush layer and herb layer1.779, 2.122-3.025 respectively. This study aims at scientific sustainable development and conservation of this rare phytobiocenose.3 the molecular ecological analysis An extraction medium with the combination of antioxidants and chelants was successfully used to obtain total DNA from the leaf tissues of L. chinensis, which can remove phenolic compound, polysaccharide and terpenoid. An economic and effective RAPD reaction system was obtained for adapting to L. chinensis RAPD markers. The optimized system include 10ng temlpate DNA, 300μM dNTPs, 2.5 mM Mg2-, 0.1U Taq DNA polymerase, 8μl Operon random primer(4pM) with 20μl of the total volume. This was the basis of large-scale reseach of many L. chinensis materials' RAPD analysis.The genetic diversity of L. chinensis, represented by 122 individuals collected from all 6 populations (niubeiliang , guangtoushan , bingjingding , fuping , taibaishan and yuhuangshan populations), was investigated with random ampified polymorphic DNA (RAPD) markers. Twenty-nine 10-mer primers primed 128 sites, of which 120(0.93) were polymorphic. The percentage of polymorphic sites (PPS) was higher (0.90) in t-pop and lower (0.75) in n-pop. In proper order, the PPS were t->b->y->c->f->n-pop (0.90> 0.87> 0.84> 0.80> 0.77> 0.75). The result reveals higher genetic diversity level of L. Chinensis than most other conifers.To reveal the relationship to molecular variation and gene flow and the habitats, it was found that 69.49% of molecular variation existed within the populations while 30.35% of which among populations estimated by Shannon phenotypic diversity index from RAPD data. The genetic different coefficient and genetic distance between populations...
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