【作者】 郑星星；

【导师】 卜兆君；

【作者基本信息】 东北师范大学 ， 湿地科学， 2011， 硕士

【摘要】 泥炭藓(Sphagnum)是特殊的苔藓植物,常为泥炭地的优势植物和主要造炭物种,在全球碳循环中发挥重要作用。全球气候变化可创造高温、干旱、水淹等诸多胁迫,对泥炭藓的生长和相互作用产生重要影响。在高山,干旱区,盐沼,温带草原等环境严酷地区的研究发现,许多目标植物的生长受益于邻体植物,然而迄今,该方面鲜有苔藓植物特别是泥炭地苔藓植物的研究报道。本研究以长白山哈泥泥炭地的丘上种大泥炭藓(Sphagnum palustre)和尖叶泥炭藓(Sphagnum capillifolium)以及丘间种喙叶泥炭藓(Sphagnum fallax)为材料,按照自然密度构建单种群与两两组合混合群落,在干旱,淹水和两种遮阴胁迫条件下进行培养,尝试研究泥炭藓生长和相互作用对胁迫的响应,在泥炭地苔藓植物中验证胁迫梯度假说。研究得出主要结果和结论如下:(1)水分是影响泥炭藓生长最为重要的因子之一。干旱对3种泥炭藓生长的抑制作用远大于邻体对泥炭藓生长的影响,使高度,生物量,分枝数降低。丘间种喙叶泥炭藓受到邻体影响均为抑制作用。丘上种尖叶泥炭藓在干旱胁迫时未受邻体影响。(2)淹水处理时,种间相互作用对泥炭藓生长影响更为强烈。研究表明喙叶泥炭藓可适应于多水环境,同时邻体促进或对其无影响。丘上种尖叶泥炭藓也受到水淹的抑制作用。丘间种喙叶泥炭藓对两种丘上种的高度,生物量,分枝数都有显著的抑制作用。甚至尖叶泥炭藓也抑制大泥炭藓的生长。(3)泥炭藓高度生长对遮阴响应最为显著,遮阴对生物量影响较小。开阔地生境的丘上种大泥炭藓对光的敏感性要高于丘间种和林缘生境的丘上种。遮阴条件下两种邻体对大泥炭藓均为竞争作用。喙叶泥炭藓在遮阴条件下具有最强的竞争能力,使邻体的生物量和分枝数下降。物种间的光竞争使丘上种尖叶泥炭藓在混合群中容重下降。(4)不同的非生物胁迫对泥炭藓水平扩展的影响存在显著的差异。水平扩展与分枝生长之间具有一定的联系。在大泥炭藓和尖叶泥炭藓的混合群落中,在遮阴条件下,主要受遮阴的影响,大泥炭藓减少尖叶泥炭藓的盖度。在干旱条件下,却主要受邻体影响,尖叶泥炭藓减少大泥炭藓盖度。遮阴导致泥炭藓的疏松生长。(5)本研究中,水分和遮阴胁迫仅降低单种群尖叶泥炭藓的C含量。在混合群中,邻体在所有胁迫条件下使尖叶泥炭藓的C含量升高。在对照条件下,邻体抑制泥炭藓C积累。在所有胁迫下,邻体与处理交互作用显著,说明在胁迫条件下邻体可促进3种泥炭藓对泥炭地的碳输入。(6)随水分和遮阴增加,泥炭藓头状枝N含量表现出增加趋势。群落中的泥炭藓N含量主要受胁迫影响,邻体对其影响不大。(7)与N含量变化相反,随水分增加C/N呈下降趋势。淹水和深遮阴使群落中的泥炭藓C/N下降。浅遮阴影响下的C/N要显著高于深遮阴下的C/N,说明少量维管植物可造成泥炭藓C/N增加,有利于泥炭藓碳积累。淹水、遮阴与干旱发生时,与尖叶泥炭藓为邻的喙叶泥炭藓C/N分别增大和减少,使泥炭地碳积累向着两个相反的方向进行。(8)本研究中,仅喙叶泥炭藓受到邻体的正相互作用,为(+,-)的种间关系,无互利共生与偏利共生关系,更多为单方向的竞争(-,0)关系。由此可见,本研究不支持胁迫梯度假说,即植物相互作用未沿着胁迫梯度由竞争转向正相互作用。泥炭藓表现出的相互作用的净结果与泥炭藓物种的竞争响应能力和胁迫忍耐能力有重要关系。更多还原

【Abstract】 Being one group of special bryophytes, Sphagnum usually is the dominant plant and major carbon manufacturer in peatlands. It plays an important role in global carbon cycle. Global change made an important impact on Sphagnum growth and plant-plant interaction. There are many studies on alpine areas, arid environment, salt marshes mires, temperate grassland and other environment stress areas, finding that the target with neighbor is better than targets without neighboring plants. There were few studies with bryophytes, especially the report with peatland bryophytes so far.In this study, I chose three Sphagnum species including one hollow specie S. fallax and two hummock species S. capillifolium and S. palustre as materials. Mono-culture and mix-culture communities were built in natural density to study the effects of drought, flooding and shading stresses on growth and plant-plant interaction between Sphagnum species. The main results and conclusions are as follows:(1) Water is one of the most important factors to impact the growth of Sphagnum. Drought stress depressed the growth of three species more than effects of neighbors, resulting in a decline of height, biomass and branch shoots. The hollow specie S. fallax was depressed by neighbors under drought. hummock specie S. capillifolium was seldom affected by neighbors.(2) Interspecies interaction were more significant under flooding stress. S. fallax was able to adept to flooding stress, and benefited from neighbors or no effects. The growth of S. palustre was depressed not only by flooding stress but also by neighbors. S. capillifolium was depressed by flooding stress. S. fallax depressed the height, biomass and branch shoots of the two hummock species significantly. Even S. capillifolium depressed the growth of S. palustre.(3) The height of the three sphagna had most significant response on shade, having feeble effect on biomass. Open-mire hummock was more sensitive than the other two species from hollow and forest edge. And the two species competed with S. palustre. S. fallax was the strongest competitor under shade, depressing the biomass and branch shoots of its neighbors. Competing for light between species made the capacity of S. capillifolium declined.(4) The coverage horizontal expansion were significantly different in different mixture conmunities and treatments. S. palustre mix-cultured with S. capillifolium, under shade, were mainly affected by shade, S. palustre coverage increased at the expense of the coverage expansion of S. capillifolium. under shade stress, Sphagna were mainly affected by neighbors, the coverage S. capillifolium expanded at the expense of the coverage of S. palustre. The shade resulted in a loose growth of Sphagnum. (5) In this study, water and shading stress only significantly reduced C concentration of mono-cultural S. capillifolium. In mix-cultured, the neighborhood increased C concentration of S. capillifolium under all stress. Under the control treatment, the C concentration was depressed by neighbors. There were significant interaction between neighborhood and all the stress treatments, indicating that the neighbors promote C input under stress in peatlands.(6) N concentration increased along water and shade level. N concentration of Sphagnum capitulum in mix-cultured were mainly affected by stress, not by neighbors.(7) The C/N is decreasing along the water increasing which is opposite to the N concentration. Flooding and deep shade depressed the C/N. The C/N under shallow shade is higher than deep shade, indicating that shading by modest vascular plant was benefit to carbon accumulation. When flooding, shade and drought stress occurs, the C/N of S. fallax mix-cultured with S. capillifolium changed along two opposite directions.(8) In this study, positive interaction was showed when other Sphagnum species as neighbor of S. fallax, with a interspecific interaction (+,-) and no mutulism and commensalism was found. Most plant-plant interactions are competition (-,0) . Hence, this study did not support Stress Gradient Hypothesis (SGH), namely plant-plant interaction did not change from competition to positive interaction along stress gradients. Sphagnum-Sphagnum interaction is related to ability of competition response and tolerant ability of stress in Sphagnum.更多还原