Study On The Community Diversity And Population Pattern Of Reaumuria Songarica In Alashan Plateau

Land desertification is one of the global environmental disasters.It directly affects the living space of human beings and the sustainable development of the economy.It poses a serious threat to biodiversity.Desertification prevention has become a major strategic task that global human need overcome.Inner Mongolia is a large agro-pastoral province in the north.The Alashan Plateau is an important ecological protection zone in the arid regions of the northwest.The special ecological environment of desertification,sandification and salinization is deep inland,and the harsh natural environment determines that the ecological environment is very fragile.Reaumuria songarica is an important community type distributed in the area.It is also a very important pasture field.It has super-resistance and ecological plasticity.It play a immeasurable role in maintaining water and soil and improving saline-alkali land.This paper analyzes the community diversity of and spatial distribution pattern of Reaumuria songarica in Alashan Plateau.It discusses the adaptation strategies to arid environment.It provides scientific basis for the protection and rational utilization of Reaumuria songarica resources.Research shows:1)It is simple of the species composition of the Reaumuria songarica community in the Alashan Plateau.There are 31 species of angiosperms belonging to 9 families and 20 genera.The layer structure of the Reaumuria songarica community consists of shrub layer and herb layer.There are 11 species of shrubs,accounting for 34.38% of the total species.The herb layer is divided into perennial herb and annual herb,of which 14 species are perennial herbs and 6 species are annual herb,accounting for 45.26% and 19.36% of the total.Decrease in climate humidity from southeast to northwest in the Alashan,the density,biomass and coverage of shrubs and herbs in the Reaumuria songarica community decreased and the height change hasn't significant law.According to the size of the important values,it can be found that the species often composed of Reaumuria songarica has Salsola passerina,Nitraria sphaerocarpa,Kalidium cuspidatum,Stipa breviflora and so on.2)It is low of the community diversity of Reaumuria songarica in Alashan Plateau.The variation of the diversity index in 10 plots was Margarlef index(Ma)>Shannon-Wienner index(H')>Simpon index(C)>Plelou index(JSW).With the decrease of the wetness,Ma and H' decrease.The change trend of C is opposite.The uniformity level has no obvious regularity.The more drought the climate,the higher the community similarity.Correlation analysis between the quantitative characteristics and diversity index of Reaumuria songarica community showed that there was a significant positive correlation between density and coverage and biomass(P<0.01).There was a significant positive correlation between Ma and H'.(P<0.01).C had a significantly negative correlation with the both(P<0.01).3)The soil moisture content in the study area is relatively low.It is less than 0.1% of each layer.The pH values are all greater than 7 and less than 10,which is alkaline.With the decrease of climate humidity,the contents of soil organic matter,total nitrogen and available phosphorus decreased.The available nitrogen content did not change significantly.The soil nutrient content is concentrated in the 0~10cm soil layer.Meteorological factors and soil factors have significant effects on the quantitative characteristics and diversity indices of Reaumuria songarica communities.4)The Reaumuria songarica population in the Alashan Plateau are mainly mature stable and declining population.According to the type of vegetation,the Reaumuria songarica population showed a spatial distribution pattern of diversity in the grassland desertification area.The type of population pattern changed with the increase of sampling scale.The distribution of aggregation to random or uniformity.In the grassland desert to typical desert overgrowth,typical desert area and extreme desert area,the Reaumuria songarica population as a whole shows a random distribution.When the environmental conditions are good,the spatial pattern of each age class is diversified.The spatial correlation shows the characteristics of diversity.With the aggravation of drought degree,the pattern of each age class is single,mainly distributed randomly.There is no correlation between grades.In the arid environment,the characteristics of Reaumuria songarica community and population distribution reflect strong adaptability and significant ecological functions.Although the Reaumuria songarica community is more stabe.In view of the serious land degradation and the limited population renewal,it should follow the laws of natural growth and distribution.We should make rational use of it in summer and fall and strengthen protection in spring and winter.The artificial tending should focus on the survival of seedlings.Artificial cultivation should preferably optimize the area with superior soil texture and plant medium-sized plants with appropriate scale to gather life.It improves the survival rate and reproduction rate of cultivation.