Zhang Hui, Väliranta Minna, Piilo Sanna, Amesbury Matthew J, Aquino-López Marco A, Roland Thomas P, Salminen-Paatero Susanna, Paatero Jussi, Lohila Annalea, Tuittila Eeva-Stiina
Institute for Atmospheric and Earth System Research (INAR), Department of Physics, University of Helsinki, Helsinki, Finland.
Environmental Change Research Unit (ECRU), Ecosystems and Environment Research Programme, University of Helsinki, Helsinki, Finland.
Glob Chang Biol. 2020 Apr;26(4):2435-2448. doi: 10.1111/gcb.15005. Epub 2020 Feb 20.
Northern boreal peatlands are important ecosystems in modulating global biogeochemical cycles, yet their biological communities and related carbon dynamics are highly sensitive to changes in climate. Despite this, the strength and recent direction of these feedbacks are still unclear. The response of boreal peatlands to climate warming has received relatively little attention compared with other northern peatland types, despite forming a large northern hemisphere-wide ecosystem. Here, we studied the response of two ombrotrophic boreal peatlands to climate variability over the last c. 200 years for which local meteorological data are available. We used remains from plants and testate amoebae to study historical changes in peatland biological communities. These data were supplemented by peat property (bulk density, carbon and nitrogen content), C, Pb and Cs analyses and were used to infer changes in peatland hydrology and carbon dynamics. In total, six peat cores, three per study site, were studied that represent different microhabitats: low hummock (LH), high lawn and low lawn. The data show a consistent drying trend over recent centuries, represented mainly as a change from wet habitat Sphagnum spp. to dry habitat S. fuscum. Summer temperature and precipitation appeared to be important drivers shaping peatland community and surface moisture conditions. Data from the driest microhabitat studied, LH, revealed a clear and strong negative linear correlation (R = .5031; p < .001) between carbon accumulation rate and peat surface moisture conditions: under dry conditions, less carbon was accumulated. This suggests that at the dry end of the moisture gradient, availability of water regulates carbon accumulation. It can be further linked to the decreased abundance of mixotrophic testate amoebae under drier conditions (R = .4207; p < .001). Our study implies that if effective precipitation decreases in the future, the carbon uptake capacity of boreal bogs may be threatened.
北方寒带泥炭地是调节全球生物地球化学循环的重要生态系统，但其生物群落及相关碳动态对气候变化高度敏感。尽管如此，这些反馈的强度和近期趋势仍不明确。与其他北方泥炭地类型相比，寒带泥炭地对气候变暖的响应受到的关注相对较少，尽管它形成了一个横跨北半球的大型生态系统。在此，我们研究了两个雨养寒带泥炭地在过去约200年（有当地气象数据）对气候变化的响应。我们利用植物和有壳变形虫的残骸来研究泥炭地生物群落的历史变化。这些数据通过泥炭特性（ bulk density、碳和氮含量）、碳、铅和铯分析得到补充，并用于推断泥炭地水文和碳动态的变化。总共研究了六个泥炭芯，每个研究地点三个，代表不同的微生境：低丘（LH）、高草甸和低草甸。数据显示近几个世纪以来存在一致的干燥趋势，主要表现为从湿生境泥炭藓属植物向旱生境fuscum泥炭藓的转变。夏季温度和降水似乎是塑造泥炭地群落和地表湿度条件的重要驱动因素。来自研究的最干燥微生境LH的数据显示，碳积累速率与泥炭地表湿度条件之间存在明显且强烈的负线性相关（R = 0.5031；p < 0.001）：在干燥条件下，积累的碳较少。这表明在湿度梯度的干燥端，水分的可利用性调节碳积累。这可以进一步与干燥条件下混合营养型有壳变形虫丰度的降低联系起来（R = 0.4207；p < 0.001）。我们的研究表明，如果未来有效降水量减少，寒带沼泽的碳吸收能力可能会受到威胁。
