河西走廊荒漠绿洲过渡带沙丘不同生境沙拐枣种群扩张特征研究

Calligonum mongolicum in Different Habitats of Sand Dunes in the Desert-oasis Ecotone of Hexi Corridor: Population Expansion Characteristics

本研究以河西走廊荒漠绿洲边缘关键天然固沙植物沙拐枣为研究对象,对流动沙丘、固定沙丘不同生境的沙拐枣种群扩张特征进行调查,旨在更全面地认识其种群扩张特征和对干旱高温环境的适应对策。结果表明:(1)沙丘不同生境,沙拐枣种群扩张方式存在显著差异:在流动沙丘,丘间低地和过渡带以有性繁殖为主,无性繁殖为辅;迎风坡和背风坡以无性繁殖为主;而随着流动沙丘固定,种群以有性繁殖为主,无性繁殖数量和所占比重显著下降,并导致种群数量下降。(2)不同生境中沙拐枣种群密度与年龄均呈显著负相关,种群以幼龄苗为主,种群最大年龄出现在丘间低地,为36龄。(3)流动沙丘不同生境根状茎主要为2年生,多年生根状茎长度较短;而固定沙丘不同生境根状茎年龄结构较为均衡。

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.