小五台山森林落叶层对天然青杨种群更新方式的影响  

Effects of forest litter layer on regeneration of Populus cathayana natural population in Xiaowutai Mountains in China

作　　者：李霄峰[1,2,3] 胥晓[2,4] 王碧霞[1,2] 黄尤优[1,2] 王志峰[1,2] 李俊钰[1,2] 

机构地区：[1]西华师范大学生命科学学院,四川南充637009 [2]西南野生动植物资源保护教育部重点实验室,四川南充637009 [3]张家口市农业环境与农产品质量管理站,河北张家口075000 [4]西华师范大学珍稀动植物研究所,四川南充637009

出　　处：《植物生态学报》2012年第2期109-116,共8页Chinese Journal of Plant Ecology

基　　金：国家自然科学基金(31170389和30771721)资助

摘　　要：通过野外样方调查和室内种子萌发实验两种方法,对河北小五台山天然青杨(Populus cathayana)种群的更新方式进行了研究,以揭示落叶层的化感作用和机械阻挡作用对青杨种子萌发的干扰机理。结果显示:1)种群样方中的幼苗都为无性繁殖的克隆分株,种子繁殖的幼苗年自然存活率为0%;2)落叶层对种子幼苗的存活率有显著影响。50mg·mL-1浓度的落叶水浸液可使青杨种子发芽率降低41%,使主根长度减少95%,100mg·mL-1浓度的落叶水浸液则完全抑制种子萌发;单层和多层落叶对种子萌发产生的影响差异不显著,都能完全阻碍种子的根系正常生长,导致幼苗脱水干枯死亡。结果表明,在高海拔山区的青杨天然林中,由于不断积累的落叶层通过化感作用和机械阻挡作用严重影响种子的萌发、定根以及正常生长,从而导致种子更新的途径受阻,而只能通过无性繁殖来完成正常的种群更新。Aims Populus cathayana, a typical riparian tree in northern China, can produce substantial seeds and numerous clones. Several studies in the last few years indicated that the proportion of seedlings and clones in the population was correlated with factors such as river flooding, soil substrates and slope gradient. Our objective was to investi- gate the regeneration mode of Populus cathayana located in high-elevation woodland of Xiaowutai Mountains, revealing why there was such a phenomenon. Methods From 2010 to 2011, we excavated 1 284 small P. cathayana saplings along an elevational gradient in high-elevation woodland of Xiaowutai Mountains to determine their method of origin. The influence of allelopathy and mechanical effects of litter layer on seedling regeneration was investigated by a series of controlled experiments. Important findings Regeneration was overwhelmingly from clonal propagation. Litter layer had a negative effect on recruitment from seed. Under treatment of different concentrations of litter layer aqueous extracts, seed germination exhibited significant differences. Compared with the control treatment, 50 mg.mL^（-1） solution decreased seed germination by 41% and root length by 95%, and 100 mg.mL^（-1） solution completely inhibited germination. Furthermore, litter layer inhibited roots of seedlings from absorbing water and rapidly caused seedling death. Therefore, litter layer prevents seedling recruitment, and clonal propagation was the only effective regeneration mode ofP cathayana in the population.

关 键 词：化感作用 落叶层 机械阻挡 青杨种群 更新方式 

分 类 号：S754.1[农业科学—森林经理学]