Mechanism Discussions Of Geographical Distribution Boundary Formation Of Four Endemic Species Of Narrow Area In Western Erdos

Potaninia mongolica Maxim., Tetraena mongolica Maxim., Helianthemumsoongoricum Schrenk and Tugarinovia mongolica Iljin is endemic plant species ofnarrow area distribute in Western Erdos.The study combined field survey and laboratory experiments, follow the soilphysical and chemical properties, spatial pattern of plant and physiological adaptiveunder drought stress to discuss the cause of geographical distribution boundaryformation. Get the following cognition about the formation of the distributionboundary:1. The natural habitats of the plants are extreme habitat that they could survive.2. The way of adapting the natural environment is always the support ofacquiring advantageous status in competition. Each plant has its own manner andpolicy to adapt to the bad habitat. They can grow in the soil of high PH value andhigh Sulfate content soil which is of great significance to hold out their status in community. Their ability to compete will weaken which will make against theirgrowth if they don't use specific environment.3. The results of the spatial pattern analysis show that there are significantlycompetitions between these plants and other shrubs or grasses of wide ecologicalamplitude. These four plants can adapt surrounding environment commendably thatmaintain the border on the orientation of grassland and desert.4. After research, we found that the bivariate function g can aquire very goodeffect when we analyze the spatial pattern of objects of finite size and shape.5. Under drought-stress, variation of the leaf water potential, free proline content,protective enzymes activity and endogenous indicate that all of these plants havegreat drought adaptability.