Ecohydrology and Biogeochemistry Research Group, Institute of Landscape Ecology, University of Muenster, Heisenbergstr. 2, 48149 Muenster, Germany; Biodiversity and Ecosystem Research Group, Institute of Landscape Ecology, University of Muenster, Heisenbergstr. 2, 48149 Muenster, Germany.
Ecohydrology and Biogeochemistry Research Group, Institute of Landscape Ecology, University of Muenster, Heisenbergstr. 2, 48149 Muenster, Germany.
Sci Total Environ. 2022 Mar 1;810:151293. doi: 10.1016/j.scitotenv.2021.151293. Epub 2021 Oct 28.
Peatlands are long-term sinks of carbon (C) and nitrogen (N) that are exposed to anthropogenic pressure. This has often induced a vegetation shift from peat mosses towards increasing presence of vascular plants. However, the impact of this vegetation shift on the sink function of peatlands remains unclear. To address this research gap, we studied C and N accumulation in a Patagonian cushion bog where a shift to the predominance of vascular cushion plants is a natural phenomenon since millennia. For comparison, long-term accumulation and decomposition patterns in a pristine Patagonian Sphagnum bog were studied. Thereto, we determined recent and long-term rates of C and N accumulation, their within-site variability, and studied plant-macrofossils. These results were related to decomposition indicators (C/N ratio, humification index, stable isotopes) of the bog types. Despite differences in decomposition indicators, long-term rates of C accumulation were of similar magnitude in the Sphagnum (21.9 g C m yr) and in the cushion bog (22.2 g C m yr). N accumulation was significantly lower in the Sphagnum bog (0.35 g N m yr) compared to the surprisingly high accumulation in the cushion bog (0.55 g N m yr). Tephra depositions in the cushion bog about 1600 cal. Years ago presumably triggered the vegetation shift towards dominance of cushion plants by a fertilization effect. C accumulation rates during past decades in the upper decimeters of peat were four times higher in the cushion bog (245 g C m yr) compared to the Sphagnum bog (64 g C m yr), but substantially decreased since the appearance of cushion plants. High decomposition rates as indicated by decomposition indicators thus apparently offset the higher productivity of cushion plants in the long term. While cushion bogs appear to be effective N sinks, their C sink function may therefore be equal to Sphagnum bogs.
泥炭地是碳 (C) 和氮 (N) 的长期汇，易受到人为压力的影响。这通常会导致植被从泥炭藓向维管植物的比例增加。然而，这种植被转变对泥炭地汇功能的影响尚不清楚。为了解决这一研究空白，我们研究了巴塔哥尼亚苔藓沼泽中的碳和氮积累，那里的植被从泥炭藓向维管束垫状植物的优势转变是几千年来的自然现象。为了比较，我们还研究了一个原始的巴塔哥尼亚水藓沼泽的长期积累和分解模式。为此，我们确定了最近和长期的碳和氮积累速率、它们在场地内的可变性，并研究了植物宏观化石。这些结果与沼泽类型的分解指标（C/N 比、腐殖化指数、稳定同位素）有关。尽管分解指标存在差异，但水藓沼泽（21.9 g C m yr）和垫状沼泽（22.2 g C m yr）的长期碳积累速率相似。与垫状沼泽惊人的高积累相比，水藓沼泽的氮积累量（0.35 g N m yr）明显较低。大约 1600 年前在垫状沼泽中沉积的火山灰可能通过施肥效应引发了植被向垫状植物优势的转变。在过去几十年中，在泥炭的上数十厘米处，垫状沼泽的碳积累速率（245 g C m yr）是水藓沼泽的四倍（64 g C m yr），但自从垫状植物出现以来，碳积累速率大幅下降。因此，高分解率（如分解指标所表明的）在长期内显然抵消了垫状植物的更高生产力。虽然垫状沼泽似乎是有效的氮汇，但它们的碳汇功能可能与水藓沼泽相当。
