Population Dynamics Of Endangered Species, Tetraena Mongolica In Fragmentation Habitats

Endangered species Tetraena mongolica is endemic to west Ordos. We firstly delimited the distribution area of the species by the techniques of RS, GIS and GPS, furthermore we studied the variation of the habitat and the population dynamics in the process of habitat fragmentation. The main results are as follows:1)Tetraena mongolica is endemic to west Ordos, and the distribution area is 2700km2. The area is an island in the deserts and other geographical obstruction, such as river and cites.2)7] mongolica experiences a complex change in the geological vicissitude. At the present, climates of the area are one of the much drier periods in the history, and the area is frangibility to human activity.3) In recent 30 years, the area of T. mongolica is decreasing and the rates of decreasing accelerate in these periods. As heterogenicity of the environment, the change of T. mongolica is varied in the distribution area, for example, the rate of decreasing is the largest in the slant industry plain area and slowest in the grazing hill area.4) The landscape diversity of T. mongolica is the largest as the intensity of disturbance is medium, and the structure of the habitats is the most complex.5) The density of T. mongolica populations is varied not significant but the coverage of population is changed significant in the distribution area, the coverage of Hainan population is largest than any others in recent years.6) The age structures of the populations are fluctuated significantly, there are no recruitment in most years. The age structure is varied in different populations, and it is difficult to recruit in many populations of Tetraena mongolica most years.7) There are significant relationship between size of individuals and quantity of fruits and seeds. The numbers of seeds are changed significant in different populations, the ones is the most in the Qianlishan population and the lowest in Dishan population, the number of seeds in Dishan population nearly is zero in 1998.8) The recruitment of populations varied in different regions, the recruitment is the highest in population of Qianlishan 1 in 1998 and 1999, but it is the highest in population of Wuda in 1993; and the recruitment is not varied significant between different times in whole distribution area.9) The germination of seeds is not varied in different times and different populations. The seeds are not limiting factor to surviving of Tetraena mongolica.