Corser Bog Pollen and Macrofossils

Pollen, spore, macrofossil and carbon data from a peatland near Cordova, Alaska, reveal insights into the climate–vegetation–carbon interactions from the initiation of the Holocene, c. the last 11.5 ka, to the present (1 ka = 1000 calibrated years before present where 0 = 1950 CE). The Holocene period is characterized by early deposition of gyttja in a pond environment with aquatics such as Nuphar polysepalum and Potamogeton, and a significant regional presence of Alnus crispa subsp. sinuata. Carbon accumulation (50 g/m2/a) was high for a short interval in the early Holocene when Sphagnum peat accumulated, but was followed by a major decline to 13 g/m2/a from 7 to 3.7 ka when Cyperaceae and ericads such as Rhododendron (formerly Ledum) groenlandicum expanded. This shift to sedge growth is representative of many peatlands throughout the south-central region of Alaska, and indicates a drier, more evaporative environment with a large decline in carbon storage. The subsequent return to Sphagnum peat after 4 ka in the Neoglacial represents a widespread shift to moister, cooler conditions, which favored a resurgence of ericads, such as Andromeda polifolia, and increased carbon accumulation rate. The sustained Alnus expansion visible in the top 10 cm of the peat profile is correlative with glacial retreat and warming of the region in the last century, and suggests this colonization will continue as temperature increases and ice melts.

来自阿拉斯加科尔多瓦附近泥炭地（peatland）的花粉、孢子、大化石与碳数据，揭示了全新世（Holocene，即距今约11.5千年至今，其中1 ka = 1000个校准年前，以公元1950年为基准年，即0代表公元1950年）以来气候-植被-碳之间的相互作用机制。全新世早期，该区域池塘环境中沉积了以萍蓬草（Nuphar polysepalum）、眼子菜（Potamogeton）等水生植物为主的腐泥（gyttja），且绿桤木皱叶亚种（Alnus crispa subsp. sinuata）在区域内分布广泛；早全新世阶段，当泥炭藓（Sphagnum）泥炭开始堆积时，曾出现一段短期的高碳积累速率（carbon accumulation）达50 g/m²/a，但在7 ka至3.7 ka期间，碳积累速率大幅下降至13 g/m²/a，此阶段莎草科（Cyperaceae）与欧石楠类植物（ericads，如原归类为Ledum的格陵兰杜鹃（Rhododendron groenlandicum））大幅扩张。这一向莎草属植物生长的转变，是阿拉斯加中南部诸多泥炭地的典型特征，反映出区域环境愈发干旱、蒸发作用增强，且碳存储量大幅降低；4 ka之后的新冰期（Neoglacial）阶段，泥炭藓泥炭重新发育，代表区域环境普遍转向更为湿润凉爽的状态，这利于欧石楠类植物（如仙女越橘（Andromeda polifolia））再度繁盛，同时碳积累速率也随之提升；泥炭剖面（peat profile）顶部10 cm处可见绿桤木持续扩张，这与近百年间该区域冰川退缩（glacial retreat）、气候变暖的现象相关，表明随着气温升高与冰川消融，这类植被定植过程仍将持续。