Reproductive Characteristics Of Calligonum Mongolicum In Different Habitats In The Desert-oasis Ecotone Of Hexi Corridor

Calligonum mongolicum,which has the characteristics of fast growth,wind erosion resistance,sand resistance,drought tolerance and easy reproduction,it is an important pioneer and dominant species of windbreak and sand-fixation in arid and semi-arid desert areas.The reproductive characteristics of Calligonum mongolicum population plays an important role in the natural regeneration,ecological restorations and treatment techniques of the desert-oasis ecotone.How to use natural resources to stabilize and expand populations with limited resources has become a scientific problem in the construction of arid regions.This paper uses the desert-oasis ecotone of Hexi Corridor(Linze Inland River basin comprehensive research Station).The key natural sand-fixing vegetation,Calligonum mongolicum,is the research object,and the reproductive characteristics of Calligonum mongolicum in different habitats of mobile sand dunes and fixed sand dunes(the leeward,the lowland,the ecotone,the windward)are carried out.Aiming at a more comprehensive understanding of the characteristics of population expansion and the adaptation countermeasures to arid and high temperature environment.The results show that:(1)There were significant differences in the reproductive patterns of Calligonum mongolicum in different habitats.In mobile sand dunes,the lowland and ecotone,the dominant pattern is sexual reproduction,and supplemented by the asexual reproduction;the windward and the leeward were mainly asexual reproduction.With the mobile sand dunes fixed,the population was mainly sexual reproduction,the number and proportion of asexual reproduction were significantly reduced,resulting in a decline in population.(2)In different habitats,soil seed banks were significantly different.The size of soil seed bank was as follows: the leeward > the lowland > the ecotone > the windward,andthe total number of soil seed banks in fixed dunes was greater than that of the mobile sand dunes.It was indicated that the leeward and the lowland were important seed reserves of the population of Calligonum mongolicum.(3)In different habitats,the age structure of the population of Calligonum mongolicum was an pyramid,all of which were growth-type populations and transformed into a stable trend.It was indicated that the Calligonum mongolicum had enhanced its adaptability through reproductive strategies,thus realizing its population expansion.(4)In different habitats,there was a significant negative correlation between population density and age.The population was dominated by young seedlings,and the largest age of the population was 36 years old in the lowland.With the increase of age,the total length of rhizomes decreased with different habitats.The rhizomes in the mobile dunes were mainly 2-year old,and the length of perennial rhizomes was short;while the age structure of rhizomes in different habitats of fixed dunes was relatively balanced.It indicates that the rhizome near the mother plant was older in the moving sand dunes,while the rhizome away from the mother plant was younger but longer.(5)There were significant differences in rhizomes and aboveground biomass in different habitats of mobile dunes.The total length of rhizomes was the longest on the windward,but the aboveground biomass was the lowest.With the fixation of mobile sand dunes,both the length of rhizomes and above-ground biomass showed a tendency to decrease in heterogeneity.In conclusion,in order to adapt to the harsh and changeable external environment of the desert-oasis ecotone desert,the population of Calligonum mongolicum were benefited from multiple reproductive strategies,including two reproductive pattern of sexual reproduction and clonal propagation,and expanded living space by using rhizomes,the formation of soil seed bank and the influence of different habitats on the natural propagation process of sandy dates.This study not only reveals the reproductive characteristics of the key natural sand-fixing plants,but also plays an important role in the natural regeneration of the population,vegetation restoration and treatment techniques inthe the desert-oasis ecotone desert.