Nordbakken J F, Ohlson M, Högberg P
University of Oslo, Botanical Museum, POB 1172 Blindern, N-0318 Oslo, Norway.
Environ Pollut. 2003;126(2):191-200. doi: 10.1016/s0269-7491(03)00194-5.
The main goals of this study were to determine the delta15N signature of quantitatively important boreal bog plants as basis for discussing their N sources, and to assess the effects of five different 3 year N treatments (i.e. 0, 5, 10, 20 and 40 kg N ha(-1) year(-1)) on the bog plants and surface peat at different depths (i.e. 0, 5, 10, 20 and 40 cm) by using 15N as tracer. Plants and peat were analyzed for N concentration, 15N natural abundance and 15N at.%. From the results we draw three main conclusions: First, the relative importance of different N sources is species-specific among bog plants. Second, an annual addition of 5 kg N ha(-1) year(-1) was sufficient to significantly increase the N concentration in Sphagnum mosses, liverworts and shallow rooted vascular plants, and an annual addition of 40 kg N ha(-1) year(-1) during 3 years was not sufficient to increase the N concentration in deep rooted plants, although the 15N content increased continuously, indicating a possible longer term effect. Third, an annual addition of 40 kg N ha(-1) year(-1) during 3 years increased the N content in surface peat at depths of 5 and 10 cm, but not at depths of 20 and 40 cm, indicating the capacity of the living Sphagnum mosses and the surface peat to take up deposited N, and thereby function as a filter.
本研究的主要目标是确定北方泥炭沼泽中具有重要定量意义的植物的δ15N特征，以此作为讨论其氮源的基础，并通过使用15N作为示踪剂，评估5种不同的3年氮处理（即0、5、10、20和40 kg N ha(-1) 年(-1)）对不同深度（即0、5、10、20和40 cm）的泥炭沼泽植物和表层泥炭的影响。对植物和泥炭进行了氮浓度、15N自然丰度和15N原子百分比的分析。从结果中我们得出三个主要结论：第一，不同氮源的相对重要性在泥炭沼泽植物中因物种而异。第二，每年添加5 kg N ha(-1) 年(-1)足以显著提高泥炭藓、地钱和浅根维管植物中的氮浓度，而在3年期间每年添加40 kg N ha(-1) 年(-1)不足以提高深根植物中的氮浓度，尽管15N含量持续增加，这表明可能存在长期影响。第三，在3年期间每年添加40 kg N ha(-1) 年(-1)会增加5和10 cm深度的表层泥炭中的氮含量，但不会增加20和40 cm深度的氮含量，这表明活的泥炭藓和表层泥炭吸收沉积氮的能力，从而起到过滤器的作用。
