BIOLOGICAL AND ECOLOGICAL CHARACTERISTICS OF THE NATIONAL SECONDARY PROTECTION SPECIES-POTANINIA MONGOLICA MAXIM Physio-ecologicalcharacteristics of photosynthesis ofendangered plant-Potaninia mongolica Eight populations genetic diversity analysis of endangered species Potaninia mongolica Maxim. based on AFLP markers Soil Seed Bank Characteristics and Dynamics of the Rare and Endangered Species Potaninia mongolica Maxim