Peatland depths and radiocarbon dates, recent decades, North America

Peatland ecosystems store about 500-600 Pg of organic carbon, largely accumulated since the last glaciation. Whether they continue to sequester carbon or release it as greenhouse gases, perhaps in large amounts, is important in Earth's temperature dynamics. Given both ages and depths of numerous dated sample peatlands, their rate of carbon sequestration can be estimated throughout the Holocene. Here we use average values for carbon content per unit volume, the geographical extent of peatlands, and ecological models of peatland establishment and growth, to reconstruct the time-trajectory of peatland carbon sequestration in North America and project it into the future. Peatlands there contain ~163 Pg of carbon. Ignoring effects of climate change and other major anthropogenic disturbances, the rate of carbon accumulation is projected to decline slowly over millennia as reduced net carbon accumulation in existing peatlands is largely balanced by new peatland establishment. Peatlands are one of few long-term terrestrial carbon sinks, probably important for global carbon regulation in future generations. This study contributes to a better understanding of these ecosystems that will assist their inclusion in earth-system models, and therefore their management to maintain carbon storage during climate change.

泥炭地生态系统储存约500~600拍克（Pg）的有机碳，其中大部分自末次冰期（Last Glaciation）以来逐步积累形成。其未来是持续固碳还是以温室气体形式大量释放碳，均对地球温度动态变化具有关键影响。依托大量经定年泥炭地样本的年代与深度数据，可估算全新世（Holocene）时期泥炭地的固碳速率。本研究借助单位体积碳含量平均值、泥炭地地理分布范围，以及泥炭地形成与生长的生态模型，重建北美地区泥炭地固碳的时间轨迹，并对其未来趋势进行预测。该区域泥炭地的碳储量约为163拍克。若忽略气候变化与其他主要人为干扰（anthropogenic disturbances）的影响，预计碳积累速率将在数千年间缓慢下降——现有泥炭地的净碳积累量减少，可通过新增泥炭地的形成在很大程度上得到抵消。泥炭地是少数长期陆地碳汇（carbon sink）之一，对后世全球碳调控或具有重要意义。本研究有助于深化对这类生态系统的认知，从而助力其被纳入地球系统模型（earth-system models），并为气候变化背景下维持碳储量的管理工作提供参考。