Climate-related changes in peatland carbon accumulation during the last millennium
Climate-related changes in peatland carbon accumulation during the last millennium
复制标题
DOI：
10.5194/bg-10-929-2013
复制
发表时间：
2013-01-01
期刊：
影响因子：
4.9
通讯作者：
Zhao, Y.
中科院分区：
文献类型：
--
作者：
Charman, D. J.;Beilman, D. W.;Zhao, Y.
泥炭地是全新世主要的陆地碳库和天然碳汇，但在气候变化中泥炭地碳的命运存在相当大的不确定性。一般认为，温度升高会加速泥炭腐烂，对气候变暖产生正反馈，促进全球碳循环正反馈。在这里，我们使用一个新的广泛的北部高纬度泥炭分布图数据库来研究过去一千年来碳积累的时空模式。与预期相反，我们的研究结果表明，北方泥炭地长期积累速率的过去变化存在一个小的负碳循环反馈。过去1000年累积的总碳与当代生长季节长度和光合有效辐射呈线性相关，表明在决定长期碳积累方面，净初级生产力的变异比分解更重要。此外，从中世纪气候异常（MCA）到小冰期（LIA）的气候转变过程中，北部泥炭地碳封存率下降，这可能是因为小冰期温度降低加上云量增加抑制了净初级生产力。其他因素包括变化的湿度状况、泥炭地分布、火灾、氮沉降、永久冻土融化和甲烷排放也将影响未来泥炭地的碳循环反馈，但我们的数据表明，在一个更温暖的未来，北部泥炭地许多地区的碳固存率可能会增加。
Peatlands are a major terrestrial carbon store and a persistent natural carbon sink during the Holocene, but there is considerable uncertainty over the fate of peatland carbon in a changing climate. It is generally assumed that higher temperatures will increase peat decay, causing a positive feedback to climate warming and contributing to the global positive carbon cycle feedback. Here we use a new extensive database of peat profiles across northern high latitudes to examine spatial and temporal patterns of carbon accumulation over the past millennium. Opposite to expectations, our results indicate a small negative carbon cycle feedback from past changes in the long-term accumulation rates of northern peatlands. Total carbon accumulated over the last 1000 yr is linearly related to contemporary growing season length and photosynthetically active radiation, suggesting that variability in net primary productivity is more important than decomposition in determining long-term carbon accumulation. Furthermore, northern peatland carbon sequestration rate declined over the climate transition from the Medieval Climate Anomaly (MCA) to the Little Ice Age (LIA), probably because of lower LIA temperatures combined with increased cloudiness suppressing net primary productivity. Other factors including changing moisture status, peatland distribution, fire, nitrogen deposition, permafrost thaw and methane emissions will also influence future peatland carbon cycle feedbacks, but our data suggest that the carbon sequestration rate could increase over many areas of northern peatlands in a warmer future.