伊犁绢蒿荒漠不同退化阶段草地土壤种子库分析

采用萌发试验研究了伊犁绢蒿(Seriphidium transillense)荒漠不同退化阶段草地土壤种子库的变化特征,以期为干旱、半干旱地区退化草地生态系统恢复提供参考依据。结果表明:伊犁绢蒿荒漠土壤种子库共有14个物种,分属8个科;从未退化阶段到重度退化阶段种子库密度由684粒·m^-2下降到443粒·m^-2,而在极度退化阶段种子库密度却升高至758粒·m^-2;种子库在空间垂直分布上表现为随土壤深度的增加而减少,有67%的种子集中在土壤表层。种子库物种丰富度和多样性指数在不同退化阶段之间变化不大,但均匀度指数呈现先上升后下降的趋势;不同退化阶段种子库间的相似性表现为随退化程度相差距离越远其土壤种子库相似性越低,土壤种子库与地上植被的Jaccard相似性指数介于0.11~0.21之间,处于极不相似水平。

Analysis of Soil Seed Banks for Different Degraded Stages of Seriphidium transillense Desert Grassland

Different degraded Seriphidium transillense desert grasslands were selected to study their soil seed bank characteristics using the seed-emergence method to guide ecological restoration of degraded ecosystems in arid and semi-arid regions.Results showed that there are 14 species belonging to eight families in soil seed banks of Seriphidium transillense desert grassland.The densities of soil seed banks decreased from 684 seeds·m-2 to 443 seeds·m-2 from non-degraded stage to heavy-degraded stage.However,the density of soil seed banks reached 758 seeds·m-2 in over-degraded stage.Soil seed bank density decreased with increased soil depth,with about 67% of total seeds gathered at the surface layer of soil.The species richness and diversity indices of soil seed banks varied little between different degraded stages.However,the evenness index showed a downward trend after rising at first.The similarities among soil seed banks of different degraded stages became lower with farther distance between degradation degrees.Jaccard similarity index between soil seed bank and above-ground vegetation varied from 0.11 to 0.21.