Study On The Dominant Population Structure And Dynamics Rules Of Nature Shrub Community In The Eastern Margin Of Badain Jaran Desert

With the deepening of human activities to the desert,the natural shrub has been greatly reduced,and the ecological environment of the community has been destroyed unprecedented.Therefore,it is an inevitable trend for the protection and sustainable development of natural shrub community to carry out the research on natural shrub community.This study combined some theoretical methods such as population structure characteristics,life table compilation,survival analysis,population dynamic change,time series prediction,and niche characteristics,to study the dominant population structure and dynamics rules of nature shrub community in the eastern margin of Badain Jaran Desert,and reveal the law of succession and development.The main findings are as follows:（1）The natural shrub community has 14 species and 21247 individuals in Badain Jaran Desert.According to the important values results,the dominant populations of this community are Haloxylon ammodendron,Reaumuria songarica and Nitraria tangutorum.（2）The age class structure of Haloxylon ammodendron population shows a“J”type,with significant differences in individual abundance.And the number of individuals increased first and then decreased with the increase height,which belonged to the growth population and the natural regeneration state was good.The development trend of diameter class structure of Reaumuria songarica population is roughly the same as that of Haloxylon ammodendron,and there are plenty of young individuals but few surviving individuals.The number of individuals of Nitraria tangutorum population reached the highest peak in theⅡage class and the height class reached the peak in₂ age class.It can be seen that the community is in the process of succession.（3）The overall development of Haloxylon ammodendron population in young age was good,and physiological aging began in theⅣage class.The population survival curve belongs to the Deevey-II type.The population survival curve of Nitraria tangutorum is close to the the Deevey-I type.Most of the plants can live to their physiological age,the early mortality is low,and when they reach their physiological age,almost all of them die in a short time.The population of Reaumuria songarica showed the same trend as that of Nitraria tangutorum.And the population survival curve belonged to Deevey-I type.（4）The population dynamic index of Haloxylon ammodendron,Reaumuria songarica and Nitraria tangutorum was greater than 0,and the(1₍1>(1(1^′>0,all of them were growth populations.When the external interference is considered,Haloxylon ammodendron and Nitraria tangutorum are less sensitive to external interference and they are stable growth types.The population growth potential of Reaumuria songarica is the largest,and it is sensitive to external disturbance.（5）The number of Haloxylon ammodendron population individuals showed an increasing trend with age class.The number of Nitraria tangutorum population individuals decreased in the second age class after the next two age classes,and the number of individuals in the other age classes showed an increasing trend as time went on.The individual numbers of Reaumuria songarica decreased in the 6th and 7th,9th and 10th age classes after the next 2 age classes,but began to increase after the next 3 age classes.（6）The niche breadth of Reaumuria songarica population was the largest,the niche breadth of Haloxylon ammodendron population was the smallest,the niche similarity ratio and niche overlap between Reaumuria songarica species and Nitraria tangutorum species was the largest,and the niche similarity ratio and niche overlap between Nitraria tangutorum species and Haloxylon ammodendron species team was the smallest,resulting in a strong competition between Nitraria tangutorum and Reaumuria songarica,Haloxylon ammodendron and Nitraria tangutorum have not formed a strong competition,which may be related to their life types,and the species-to-niche similarity ratio of the plant population composition of the same life type is larger.