Abstract:

Taking Calligonum mongolicum, a key natural sand fixing plant in the desert-oasis ecotone of Hexi corridor, as the research object, we investigated the population expansion characteristics of Calligonum mongolicum at different habitants (mobile and stabilized dunes), to understand the population expansion characteristics of Calligonum mongolicum and its adaptive countermeasures to drought and high temperature in a more comprehensive way. The results showed that: (1) there were significant differences of population expansion of Calligonum mongolicum in different habitats; in mobile sand dunes, the lowland and ecotone, the population expansion was mainly dominated by sexual reproduction, and was supplemented by asexual reproduction, but was mainly dominated by asexual reproduction at the windward and the leeward slopes; with the fixation of mobile sand dunes, the population was dominated by sexual reproduction, the number and proportion of asexual reproduction decreased significantly, resulting in population decrease; (2) in different habitats, the population density of Calligonum mongolicum had a significantly negative relationship with its age; the population was dominated by young seedlings, and the oldest age (36-year-old) of the population appeared in the hilly lowlands; (3) the rhizomes in mobile sand dunes in different habitats were mainly 2 years old, and the length of perennial rhizomes was shorter; the age structure of rhizomes in different habitats of stabilized sand dunes was more balanced.

Key words: desert-oasis ecotone, different habitats, Hexi corridor, Calligonum mongolicum, reproductive characteristics