For centuries European peatlands have been degrading along with drainage, land use and climate changes. Increasing pressure on peatland ecosystems calls for a more cost-efficient method to indicate the current state of peatlands and the success of restoration efforts. Metabolic pathways in peatland soils are imprinted in stable isotope compositions due to differences in microorganism communities and their metabolic pathways. Therefore, we hypothesize that depth profiles of nitrogen stable isotope values provide a promising opportunity to detect peatland decomposition or restoration. We studied five peatlands, namely Degerö Stormyr (northern Sweden), Lakkasuo (central Finland) and three mires in the Black Forest (southern Germany). At all locations, cores were taken from adjacent drained (or rewetted) and natural sites to identify δ¹⁵N trends that could indicate changes due to drainage and restoration. At all drained (and rewetted) sites we found a distinct peak (“turning point”) of the δ¹⁵N values in the center of the drained horizon. We did a fatty acids (FAs) analysis to link our results to microbial community composition. As markers, we distinguished between one fungal-derived FA (C18:2ω9c) and four bacterial-derived FAs. For bacteria, we looked for one general bacterial-derived FA (C14:0), two FAs for gram-positive bacteria (i-C15:0; a-C15:0), and one FA for gram-negative bacteria (C16:1ω9c). In accordance with other studies, our results suggest that fungi dominate the microbial metabolism in the upper aerobic peat horizon. This is reflected by depleted δ¹⁵N values. Moving downwards, the drained horizon conditions slowly switch to oxygen limitation. Consequently, fungal-derived FAs decrease whereas bacterial-derived FAs rise. The highest diversity of microbial-derived FAs is indicated by the δ¹⁵N turning point. Below the δ¹⁵N turning point, oxygen is increasingly limited and concentrations of all microbial-derived FAs are decreasing down to the onset of the permanently waterlogged anaerobic horizon. Peatland cores with restoration successes again show, above the formerly drained horizon, no depth trend of the isotopic values. Hence, we conclude that δ¹⁵N stable isotope values reflect microbial community composition, which differs between drained and natural peatlands.

中文翻译：

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真菌的开关以在自然，排水和再润湿贫营养细菌泥炭地降解反映在I' ¹⁵ N和脂肪酸组成

几个世纪以来，欧洲泥炭地一直在退化，排水，土地利用和气候变化也是如此。对泥炭地生态系统的压力越来越大，需要一种更具成本效益的方法来表明泥炭地的现状和恢复工作的成功。泥炭地土壤中的代谢途径由于微生物群落及其代谢途径的差异而被印记在稳定的同位素组成中。因此，我们假设氮稳定同位素值的深度剖面为检测泥炭地的分解或恢复提供了一个有希望的机会。我们研究了五个泥炭地，分别是DegeréStormyr（瑞典北部），Lakkasuo（芬兰中部）和黑森林（德国南部）中的三个泥潭。在所有位置，取自邻近排水（或重新沉淀）和自然地点的岩心，以识别I' ¹⁵ ñ趋势可能表明，由于排水和恢复的变化。在全部倒掉（和再湿）的网站，我们发现AA不同峰值的（A ????转向点A ????） I' ¹⁵在排水地平线中心的N值。我们进行了脂肪酸（FAs）分析，以将我们的结果与微生物群落组成联系起来。作为标记，我们区分了一种真菌来源的FA（C18：2 → 9c）和四种细菌来源的FA。对于细菌，我们寻找一种通用的细菌衍生FA（C14：0），两种针对革兰氏阳性细菌的FA（i-C15：0; a-C15：0），以及一种针对革兰氏阴性细菌的FA（C16： 1 Ï??9c）。根据其他研究，我们的结果表明，真菌在有氧泥炭地层中占主导地位。这是通过耗尽反射I' ¹⁵的N值。向下移动，排水层条件慢慢切换到氧气限制。因此，源自真菌的FA减少而源自细菌的FA上升。微生物衍生的FA的最高分集是由指示 I' ¹⁵转向点。下面以I' ¹⁵N转折点，氧气越来越受到限制，所有微生物衍生的FA的浓度一直下降到永久浸水的厌氧层期开始。泥炭地带岩心的恢复成功再次表明，在以前的排水层上方，同位素值没有深度趋势。因此，我们得出结论， I' ¹⁵ Ñ稳定同位素值反映微生物群落的组合物，其排出并自然泥炭地之间不同。