| Biodiversity conservation is an inter-subject, with bases of profound theories and extensive applicated fields, which not only concerns about the theory and methods of ecology, genetics and evolution, but also discusses the evolutionary mechanism, principles and methods of biodiversity conservation. Facing the fast biodiversity decrease and the environmental degradation, conservation biology has become a discipline arose the great public attention. The objectives of conservation biology is to understand the effect of human activities on biodiversity and to develop practical methods to keep species from extinction as well as the theory, measures and technology of biodiversity conservation. Magnolia amoena belongs to Magnoliaceae and Magnolia, and an endemic species of East China, being an ornamental or used as fragrance and pharmacy plant. Because of a rapid decrease in quantity and distribution area, Magnolia amoena was listed in the third class of the national protection plant species in 1984.In present, Magnolia amoena is only found in Anhui, zhejiang, Jiangsu, Jiangxi etc provinces and the natural distribution area of M. amoena is very narrow, fragmentary .This dissertation is mainly dealing with its morphological characters, population biology, pollination biology and molecular biology. According to the results from this study, the factors that caused the present dangerous situation of M. amoena have been analyzed and several measures for effective protecting have also been proposed. The conclusions are as follows:1. The anatomical character of M.amoena is primitive, bisexual flower, lots of pistil and stamina,filament is much shorter than anther, M.amoena has no hair III or cuticle;Compared with its kindred cosmopolite species M.denudata,they have much common in anatomical characters. From this, it is possible to ascertain that morphological characters are not a threatening factor.2. The population of M.amoena exhibits clumped distribution, most of them are rather small. Field investigation showed that the young trees of M.amoena are too few to provide enough recruitment and ageing phenomena is severely. The population size is tending to decline which signified M.amoena species is in danger.3. M.amoena is suitable to cool, moist, misty, fertile and humus-riched acidic soil with well-drained and loose structure. As an accompany species in its communities, M.amoena does not have a strong competition predominance against other species.4. The flower of M.amoena is beginning in early March. Every year many people often pick up its buds used as medicine, so its seed-set is not high. In addition, the seed quality of M.amoena was very poor, long dormancy and percentage of seeds with vitality was low. What's more, in nature, seeds often were rotted or eaten by insects. All of them restrict seeds from germinating into seedlings in field and spreading of populations, so the renewal of the populations is very poor. Seed germination tests in lab showed that the germination rate of freshly harvested seeds was zero, while dealing with low temperature of the seeds coated with sand in advance could enhance seed germination rate. 5. The genetic diversity of individuals from 12 natural populations of M.amoena from different distribution regions was analyzed by using random amplified polymorphic DNA(RAPD). 14 primers were screened from 40 ten-bp arbitrary primers, and a total of 94 DNA fragments were amplified, among which 23 were polymorphic. DNA molecular dendrograms were established for the 12 natural populations based on UPGMA and Neighbor-Joining. The result showed: (1) M.amoena has a low genetic diversity, and its adaptability to environmental change is weak; (2) The genetic diversity of M.amoena among populations is higher than within a population. In addition, the genetic diversity of M.amoena natural populations are primarily related to their geographic distribution; More distance between them, more difference; The low level of genetic variation of I...
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