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基于保水剂应用的高寒沙地土壤种子库激活效应

Activation effect of soil seed bank in alpine sandy land based on the application of water-retaining agent

  • 摘要: 为探究保水剂对黄河上游高寒沙地土壤种子库的激活效应,以若尔盖天然草地、轻度沙地、中度沙地、重度沙地、极重度沙地为研究对象,分析其物种组成、生活型,通过围封(中度沙地、重度沙地、极重度沙地)样地,在样地上施加不同量保水剂,研究不同保水剂用量下萌发物种数、植株数量、植物生物量、群落盖度的变化。结果表明:(1)四川黄河上游高寒沙地共统计到植物种子 26种,均为草本植物,表现出该区域种子的科、属、种较为集中、物种组成类型单一。(2)随着保水剂施用量的增加,中度沙化地生长的草本植物物种数、植株数量显著高于对照,施用0.25 kg·m−2保水剂时达到最大萌发数量和最大萌发物种数;重度沙化地、极重度沙化地保水剂处理组植株数量显著高于对照,随着保水剂施用量增加植株数量总体呈先增加后降低的趋势,施用量为0.25 kg·m−2时幼苗数量达到峰值。(3)就样地草本植物群落生物量和盖度而言,施用保水剂样地植物生物量、群落盖度总体上高于对照,除极重度沙化地外,中度沙地、重度沙地生物量和盖度在施用量0.25 kg·m−2时达到最大,之后生物量、盖度逐渐降低。在高寒沙地土壤种子库激活实验中,保水剂用量为 0.25 kg·m−2时能满足植物种子的萌发与生长,进一步提高保水剂的施用量对植物生物量的增加无显著影响,反而有降低的可能。根据保水剂处理条件下土壤种子库物种萌发的情况,结合研究区原生植被情况,四川嵩草、赖草、羊茅、草地早熟禾、线叶嵩草可作为研究区生态恢复的参考物种。

     

    Abstract: To investigate the activation effect of water-retaining agent on soil seed bank in alpine sandy land in the upper reaches of the Yellow River, natural grassland, mild sandy land, moderate sandy land, severe sandy land, and extremely severe sandy land in Zoige were taken as the research objects, and the species composition and life form were analyzed. By enclousing the sample plots (moderate sandy land, severe sandy land and extremely severe sandy land), and applying different amounts of water retaining agent on the enclosed plots, the changes in the number of sprout species, plant number, plant biomass and community coverage under different water-retaining agent dosages were studied. The results showed that: (1) A total of 26 plant seeds were counted in the alpine sandy land in the upper reaches of the Yellow River in Sichuan, all of which were herbaceous plants, indicating that the families, genera, and species of seeds in this region were relatively concentrated, and the species composition type was single. (2) With the increase of the application amount of water-retaining agent, the number of herbaceous plant species and plants growing in moderate sandy areas was significantly higher than that of the control. The maximum number of germination species and the maximum germination species were reached when 0.25 kg·m−2 water-retaining agent was applied. The number of plants in the treatment group with water-retaining agent in severe and extremely severe sandy land was significantly higher than that in the control group. With the increase of water-retaining agent applicaiton, the number of plants first increased and then decreased, and the number of seedlings reached the peak when the application amount was 0.25kg·m−2. (3) In terms of the biomass and coverage of herbaceous plant communities in the sample plot, the biomass and coverage of plants in the application of water retaining agents were generally higher than those in the control plot. Except for the extremely severe sandy land, the biomass and coverage of moderate and severe sandy land reached the maximum when the application rate of 0.25 kg·m−2, and then gradually decreased. In the activation experiment of soil seed bank in alpine sandy land, the amount of water-retaining agent was 0.25 kg·m−2, which could meet the germination and growth of plant seeds. Further increasing the application amount of water-retaining agent had no significant effect on the increase of plant biomass, but may actually decreased it. According to the germination of soil seed bank species under the condition of water-retaining agent treatment, combined with the original vegetation in the study area, Carex setschwanensis, Leymus secalinus, Festuca ovina, Kengyilia rigidula, Poa pratensis, C. capillifolia, and C. sinosupina could be used as reference species for ecological restoration in the study area.

     

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