Responses of the mosses Sphagnum capillifolium and Polytrichum strictum to nitrogen deposition in a bog: growth, ground cover, and CO2 exchange
Responses of the mosses Sphagnum capillifolium and Polytrichum strictum to nitrogen deposition in a bog: growth, ground cover, and CO2 exchange
复制标题
DOI：
10.1139/cjb-2015-0183
复制
发表时间：
2016-02-01
期刊：
影响因子：
1.1
通讯作者：
Chong, Mandy
中科院分区：
文献类型：
--
作者：
Juutinen, Sari;Moore, Tim R.;Chong, Mandy
先前的研究表明，大气氮（N）沉降对泥炭藓是有害的，泥炭藓是一组苔藓，对北方泥炭地的碳循环很重要。人们对物种相互作用知之甚少，例如高苔多毛菌（Polytrichum strictum Menzies ex Brid）的相对反应。和泥炭藓。研究了氮沉降对藓类植物泥炭藓（Sphagnumcapillifolium）生长、丰度和CO2交换的影响。Hedw.和多毛菌在一个温和的沼泽实验。高氮处理（6.4gN·m（-2）·年（-1））在处理的第4年和第5年显著降低了泥炭藓的生长和覆盖，而与对照相比，金发藓的生长和覆盖显著增加。净CO2交换，总光合作用（P-g），和暗呼吸（R）在完整的苔藓核心，这是在第5年的治疗，被升高的核心，已与高剂量的N处理，与对照相比，这是与增加的丰富的多毛类。然而，去除了多毛菌的苔藓核心在高剂量N处理下增加了基于质量的R。结果表明，S.在Mer Bleue的Capillifolium可能接近N饱和，因为5年的高剂量N负荷（6.4 g N.m（-2）.year（-1）+背景）对该物种有害，可能是由于呼吸代价增加。多毛菌通过分配多余的氮用于生长，至少在短期内具有竞争优势。苔藓层组成的这种变化值得进一步关注，因为转向更容易分解的垃圾，而不相应增加植物产量，可能会减少沼泽的碳固存。
Previous studies have shown that atmospheric nitrogen (N) deposition is detrimental to sphagna, which are a group of mosses that are important for carbon cycling in northern peatlands. Little is known about species interactions, such as relative responses of tall moss Polytrichum strictum Menzies ex Brid. and sphagna. We studied the effects of N deposition on growth, abundance, and CO2 exchange of the moss species Sphagnum capillifolium (Ehrh.) Hedw. and Polytrichum strictum in an experiment at a temperate bog. Sphagnum growth and cover decreased significantly with high-dose N treatment (6.4 g N.m(-2).year(-1)) in years 4 and 5 of treatment, whereas the same parameters increased for Polytrichum compared with the control. Net CO2 exchange, gross photosynthesis (P-g), and dark respiration (R) in the intact moss cores, which were measured in year 5 of treatment, were elevated in the cores that had been treated with the high-dose of N, compared with the control, and this was associated with increased abundance of Polytrichum. The moss cores where Polytrichum was removed, however, had increased mass-based R with the high-dose N treatment. Our results showed that S. capillifolium at Mer Bleue may be close to N saturation, as 5 years of high-dose N loading (6.4 g N.m(-2).year(-1) + background) was harmful to this species, possibly as a result of increased respiratory cost. Polytrichum strictum had a competitive advantage, at least in the short-term, through allocating excess N to growth. This change in moss layer composition deserves further attention, as a shift to more easily decomposable litter, without corresponding increases in plant production, could reduce the carbon sequestration of the bog.