State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Institute for Peat and Mire Research, Northeast Normal University, Renmin, Changchun, China.
Oecologia. 2011 Jun;166(2):555-63. doi: 10.1007/s00442-010-1880-1. Epub 2010 Dec 19.
Ecosystem processes of northern peatlands are largely governed by the vitality and species composition in the bryophyte layer, and may be affected by global warming and eutrophication. In a factorial experiment in northeast China, we tested the effects of raised levels of nitrogen (0, 1 and 2 g m(-2) year(-1)), phosphorus (0, 0.1 and 0.2 g m(-2) year(-1)) and temperature (ambient and +3°C) on Polytrichum strictum, Sphagnum magellanicum and S. palustre, to see if the effects could be altered by inter-specific interactions. In all species, growth declined with nitrogen addition and increased with phosphorus addition, but only P. strictum responded to raised temperature with increased production of side-shoots (branching). In Sphagnum, growth and branching changed in the same direction, but in Polytrichum, the two responses were uncoupled: with nitrogen addition there was a decrease in growth (smaller than in Sphagnum) but an increase in branching; with phosphorus addition growth increased but branching was unaffected. There were no two-way interactions among the P, N and T treatments. With increasing temperature, our results indicate that S. palustre should decrease relative to P. strictum (Polytrichum increased its branching and had a negative neighbor effect on S. palustre). With a slight increase in phosphorus availability, the increase in length growth and production of side-shoots in P. strictum and S. magellanicum may give them a competitive superiority over S. palustre. The negative response in Sphagnum to nitrogen could favor the expansion of vascular plants, but P. strictum may endure thanks to its increased branching.
北方泥炭地的生态系统过程在很大程度上受苔藓层的活力和物种组成控制，可能受到全球变暖与富营养化的影响。在中国东北的一个析因实验中，我们检验了氮（0、1 和 2 g m(-2) year(-1)）、磷（0、0.1 和 0.2 g m(-2) year(-1)）和温度（对照和+3°C）水平升高对密叶曲尾藓、大金发藓和泥炭藓的影响，以观察种间相互作用是否会改变这些影响。在所有物种中，生长随氮添加而下降，随磷添加而增加，但只有密叶曲尾藓对升温做出反应，产生更多的侧枝（分枝）。在大金发藓中，生长和分枝朝着相同的方向变化，但在密叶曲尾藓中，这两个反应是解偶联的：氮添加时生长下降（小于大金发藓）但分枝增加；磷添加时生长增加而分枝不受影响。磷、氮和温度处理之间没有双向相互作用。随着温度升高，我们的结果表明，相对于密叶曲尾藓，泥炭藓的比例应该减少（密叶曲尾藓分枝增加，对泥炭藓有负邻居效应）。磷供应略有增加时，密叶曲尾藓和大金发藓的长度生长和侧枝产生增加，可能使它们比泥炭藓具有竞争优势。氮对大金发藓的负响应可能有利于维管束植物的扩张，但密叶曲尾藓可能因其分枝增加而得以忍受。
