Abstract The long-term carbon (C) and vegetation dynamics of tropical, high-Andean cushion peatlands are poorly understood. Here, we present radiocarbon-dated paleoecological records and modern microclimate data from high-elevation peatlands currently dominated by the cushion plant Distichia muscoides in the paramo (alpine tundra) of the eastern Colombian Andes. Focusing on a well-dated 4300-year-old peat core collected at 4194 m elevation from the Sierra Nevada del Cocuy, we investigated the response of peatland vegetation to hydroclimate changes and environmental controls on C accumulation. In addition, we carried out a regional synthesis of existing C accumulation data from northern Andean peatlands to place our new results in broad geographic and temporal context over the last 17,000 years. Our results show that the current Distichia-dominated peatlands are a recent landscape feature on El Cocuy occurring only during the last ∼250 years. The Distichia peatlands have extremely high sediment accumulation rates of up to 1 cm yr−1 and C accumulation rates between 183.7 and 849.5 g C m−2 yr−1, decreasing with the elevation of a site. These rates far exceed an expected modern C accumulation rate of 110 g C m−2 yr−1, calculated by extrapolating an exponential function from a late Holocene average C accumulation rate of 48.6 g C m−2 yr−1 for the northern Andes. This suggests that recent Distichia establishment represents an acceleration of C accumulation at a rate higher than expected from decomposition-related autogenic effects. Before the modern climate warming period, our record indicates that Distichia cushions have only grown intermittently, often after the peatland was flooded with mineral sediments. Mineral sediment deposits at 3290, 2590, 1620, 930, and 860 cal. yr BP correspond with wet intervals from lake-derived records of hydroclimate change in the northern Andes and indicate increases in precipitation and subsequent in-wash of mineral sediments. However, within the last 150 years, mineral sediment deposition has increased in frequency, likely due to warming-induced melting of permanent snow and ice mobilizing exposed fluvio-glacial sediments. Increased mineral nutrients, rising temperatures, and strong diurnal temperature contrast in the tropical mountains may explain the rapid C accumulation rates. Taken together, we show that Andean peatlands have experienced the largest shift in vegetation and C accumulation rates in the last 250 years than at any other time during the last 4000 years.

中文翻译：

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哥伦比亚东部安第斯山脉以泥炭藓为主的泥炭地全新世碳积累的环境控制

摘要 热带、高安第斯垫层泥炭地的长期碳 (C) 和植被动态知之甚少。在这里，我们展示了来自高海拔泥炭地的放射性碳测年古生态记录和现代小气候数据，这些泥炭地目前由哥伦比亚安第斯东部帕拉莫（高山苔原）的垫层植物 Distichia muscoides 主导。我们以从内华达山德尔科库伊海拔 4194 m 处收集的具有 4300 年历史的泥炭核心为重点，研究了泥炭地植被对水文气候变化的响应以及对 C 积累的环境控制。此外，我们对来自安第斯北部泥炭地的现有 C 积累数据进行了区域综合，以将我们的新结果置于过去 17,000 年的广泛地理和时间背景中。我们的结果表明，目前以 Ditichia 为主的泥炭地是 El Cocuy 上最近出现的景观特征，仅发生在过去 250 年左右。Distichia 泥炭地具有极高的沉积物积累率，高达 1 cm yr-1，C 积累率在 183.7 和 849.5 g C·m-2 yr-1 之间，随着场地的海拔升高而降低。这些速率远远超过预期的现代 C 积累速率 110 g C m-2 yr-1，这是通过从安第斯山脉北部 48.6 g C m-2 yr-1 的晚全新世平均 C 积累速率外推指数函数计算得出的。这表明最近的 Ditichia 建立代表了 C 积累的加速，其速度高于分解相关自生效应的预期。在现代气候变暖期之前，我们的记录表明，Distichia 垫层只是间歇性地生长，通常是在泥炭地被矿物沉积物淹没之后。矿物沉积物沉积在 3290、2590、1620、930 和 860 cal。yr BP 对应于来自安第斯山脉北部水文气候变化的湖泊衍生记录的湿间隔，并表明降水增加和随后的矿物沉积物冲刷。然而，在过去的 150 年中，矿物沉积物沉积的频率有所增加，这可能是由于变暖引起的永久冰雪融化，使暴露的河流冰川沉积物流动起来。热带山区矿质养分增加、温度升高和昼夜温差强烈，可以解释快速的 C 积累速率。综合起来，