Northern peatlands sequester carbon (C) and nitrogen (N) over millennia, at variable rates that depend on climate, environmental variables and anthropogenic activity. The ombrotrophic peatlands of central and northern Alberta (Canada) have developed under variable climate conditions during the last hundreds to thousands of years, while in the course of the twentieth century, some regions were also likely subjected to anthropogenic disturbance. We aimed to quantify peat C and N accumulation rates for the last millennium from seven peatlands to estimate the relative influence of climate and anthropogenic disturbance on C accumulation dynamics. Peatlands have accumulated C at an average rate of 25.3 g C m−2 year−1 over the last millennium. Overall, climate was likely a major factor as, on average, highest apparent rates of C accumulation were found around 1100 CE, during the warmer Medieval Climate Anomaly, with lowest rates during the Little Ice Age, around 1750 CE. Local factors, such as disturbance, played a role in C sequestration at the site scale. The average N accumulation rate was 0.55 g N m−2 year−1, with high inter- and intra-site variability. In general, N accumulation mirrored patterns in C sequestration for peat deposited pre-1850 CE. However, higher N accumulation rates observed after 1850 CE, averaging 0.94 g N m−2 year−1, were not correlated with C accumulation. Moreover, some of the historically strongly accumulating sites may have become less efficient in sequestering C, and vice versa. All seven sites showed a marked decrease in δ15N when comparing pre- and post-1850 timeframes, consistent with increasing post-1850 N additions from an atmospheric source, likely biological N fixation. Overall, N was not a driving factor for C accumulation.

中文翻译：

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过去千年加拿大艾伯塔省中部和北部的同质营养泥炭地的碳和氮积累率

数千年来，北部泥炭地以不同的速率固存碳 (C) 和氮 (N)，这取决于气候、环境变量和人为活动。阿尔伯塔省中部和北部（加拿大）的同营养泥炭地在过去数百至数千年的气候条件下发展起来，而在二十世纪的过程中，一些地区也可能受到人为干扰。我们旨在量化过去一千年七个泥炭地的泥炭 C 和 N 积累率，以估计气候和人为干扰对 C 积累动态的相对影响。在过去的千年里，泥炭地以平均 25.3 g C m−2 year−1 的速度积累了 C。总体而言，气候可能是一个主要因素，因为平均而言，在温暖的中世纪气候异常期间，在公元 1100 年左右发现了 C 积累的最高表观速率，在小冰河时代，即公元 1750 年左右，速率最低。局部因素，如干扰，在现场规模的 C 封存中发挥了作用。平均 N 积累率为 0.55 g N m-2 year-1，具有较高的站点间和站点内变异性。一般而言，N 积累反映了公元 1850 年之前沉积的泥炭的 C 封存模式。然而，在 1850 CE 之后观察到的更高的 N 积累率，平均 0.94 g N m-2 year-1，与 C 积累无关。此外，一些历史上强烈积累的站点可能在隔离 C 方面效率较低，反之亦然。当比较 1850 年前和 1850 年后的时间范围时，所有七个站点都显示 δ15N 显着下降，与 1850 年后大气源中不断增加的 N 相一致，可能是生物固氮。总体而言，N 不是 C 积累的驱动因素。