泥炭地特征性环境因子促进泥炭藓持久孢子库的形成

研究泥炭地特征性环境因子——淹水、少氧和化感物质对泥炭藓孢子持久性的影响, 可深入理解泥炭地泥炭藓持久孢子库的形成机制, 为退化泥炭地泥炭藓地被恢复研究提供参考。该研究以藓丘种和丘间种两种泥炭藓的孢子为试验材料, 通过室内模拟控制实验的方法, 研究泥炭藓孢子在空气、超纯水、泥炭地地表水和泥炭藓沥出液中, 及3种速率充气下, 孢子萌发力持久性的变化。经充气处理后, 泥炭藓孢子持久性显著低于不充气处理。不充气时, 泥炭藓孢子在含有化感物质的泥炭地地表水和泥炭藓沥出液中保存, 持久性显著高于在超纯水中保存。通径分析结果显示, 溶解氧是影响泥炭地泥炭藓孢子持久性的主要因子和限制因子, 养分元素氮(TN)和磷(TP)的浓度为孢子持久性的负作用因子。研究结果表明, 泥炭藓孢子散布于苔藓地被基质或淹水的丘间生境中, 比暴露于空气或在无化感物质的水中, 能更好地维持萌发力。泥炭地中, 泥炭藓孢子和其他植物的繁殖体的超长寿命可能归因于少氧、养分贫乏和丰富的化感物质等泥炭地特征性环境因子。

Characteristic environmental factors in peatlands facilitate the formation of persistent Sphagnum spore banks

Aims To test the effects of environmental factors in peatlands on the persistence of Sphagnum spore germinability. The results may help to understand the mechanisms behind the formation of Sphagnum spore banks in peatlands. They can also provide valuable insights for restoration of degraded peatlands. Methods We determined the initial germination percentage in spores of two Sphagnum species (hummock- forming Sphagnum capillifolium and hollow-forming S. flexuosum) and then stored them for 60 days, either dry, in ultrapure water, peatland surface water or Sphagnum water leachate. We varied oxygen concentration by injecting air at three concentrations during the storage experiment. After retrieval from experimental storage, spore germinability was assessed. Important findings Spore germinability was lower after air-injection than under oxygen-deficiency. Spore germinability was higher after storage in the peatland surface and Sphagnum leachate water, having high concentrations of allelochemicals, than in ultrapure water, under oxygen-deficiency. Path analysis showed that dissolved oxygen is the main factor negatively affecting Sphagnum spore persistence in peatlands. Nitrogen (TN) and phosphorus (TP) also affect spore persistence negatively. These results indicate that once dispersed onto Sphagnum substrates or waterlogged hollows, Sphagnum spores can remain viable longer than when exposed to dry conditions or in water without allelochemicals. Extreme longevity of Sphagnum spores and other plant propagules may be attributed to the oxygen-deficient, nutrient-poor and allelopathic substrates in peatlands.