The endangered characteristics and mechanism of the endemic relict shrub Tetraena mongolica Maxim
孑遗植物四合木(Tetraena mongolica)的濒危肇因与机制

The conservation biological study on the typical endangered plant species of Tetraena mongolica Maxim was carried out to examine endangered ecological process and characteristics in China from 1995 through 2006. The paper reviewed thoroughly the biological characteristics of tendency to endangered status, the geographic distribution, the habitat condition, the population dynamics, and the features of sexual reproduction and asexual propagation of T. mongolica. The authors also explained the modeling of the Leslie matrix, time series analysis for predicting population dynamics, fractal theory for describing population distribution pattern, and patterns of endangered population growth. Based on the comprehensive analysis, underlying endangered mechanisms and characteristics of T. mongolica were projected. T. mongolica distributes in confined west Erdos and the area is shrinking. Age structure indicates a population decline and spatial distribution follows a conglomeration pattern. The adaptation and living abilities demonstrate more weakness than the widespread species such as poorer species competition. The seed yields less and shows impotent. The percentage germination is lower and mortality of seedling higher. On the other hand, asexual propagation only functions limitedly as a kind of compensation after failure of sexual reproduction. In the community context, the favorable influence from other living organisms becomes weaker, whereas, the unfavorable influence stronger in natural situations as the result of disturbed ecological balance and reduced biodiversity. The endangered population of T. mongolica revealed a declining status with predicting model analysis. That eventually dues to both the internal factors, such as embryogenesis abortion, and feeble abilities of living, external factors such as and disturbances as well. Moreover, tougher disturbances would turn to the vital reason for T. mongolica to go extinct. In summary, the above endangered characteristics have accorded with the approved standards of ex situ conservation of relict plants. Therefore, T. mongolica should be protected with sufficient support of research.