The consequences of the Little Ice Age period over peat sequestration in northern peatlands

这项为期5年的研究计划延续了我之前在整个全新世期间进行的研究活动，提供了来自加拿大东北部北方生物群系不同生态区域的泥炭起始、泥炭地发展和相关碳积累的原始数据。我们的研究结果揭示了全新世碳在不同季节的区域时空累积，并证实了长期气候变化在泥炭地动态和相关碳封存中的重要驱动作用。近年来，国际上已开始加强对新冰川期（3000 BP）、中世纪气候异常期（350-1200 BP）和小冰期（1350-1850 AD）等影响泥炭积累的关键气候期的认识。在北方国家，小冰期代表了一个关键时期，因为它在过去几个世纪里影响了永久冻土的恶化。如今，在开放的北方森林的最北部地区和针叶林中，一些残余的永久冻土仍然存在，而在其他一些地区的地貌指数表明，它最近正在融化。最近的寒冷异常期开始的详细重建，其对泥炭堆积的影响以及最近受最近变暖影响的消失将被用作类似物，以记录加拿大东北部今天北极变暖的后果。我们打算记录外部强迫的影响，如北大西洋涛动（NAO）的变化、太阳辐射和/或火山活动，这些已被确定为这种冷却的主要原因。大型化石、晚期变形虫、腐殖质化和同位素分析等方法，加上精确的年代学（14C和210Pb）和年龄模型，将支持这一以寒冷气候扰动和随后变暖为特征的时期的详细重建。改进方法的结果也将纳入国际努力（欧洲、美国、加拿大其他地区），以合并各种泥炭数据库和开发产出，这些产出将对响应国际植物保护公约报告的PMIP（古气候模拟比对项目）和PCMIP（古碳模拟比对项目）建模者社区有用。

The research program presented in this 5-years proposal follows my precedent research activities conducted over the entire Holocene period providing original data on peat initiation, peatland development and related C accumulation from different ecoregions of the northeastern canadian boreal biome. Our results present regional spatial and temporal Holocene C accumulation along with distinct seasonal patterns and confirm the role of long-term climate variations as an important driver in peatland dynamics and related C sequestration. In the international community, recent initiatives have been taken up to enhance the understanding of critical climate periods on peat accumulation such as the Neoglacial period (3000 BP), the Medieval Climate Anomaly (350-1200 BP) and the Little Ice Age (LIA) (1350-1850 AD). In northern countries, the LIA represents a critical period as it has influenced permafrost aggradation over the past centuries. Nowadays, some relict permafrost remains in the most northern regions of the open boreal forest and in the taiga while geomorphic indices in some other part of the landscape suggests its recent melting. The detailed reconstruction of the onset of this recent cold anomaly period, its impact over peat accumulation and its recent disappearance influenced by the recent warming will be used as analogs to document the consequences of the present-day arctic warming in northeastern Canada. We intend to document the impacts of external forcings such as the variations in the North Atlantic Oscillation (NAO), solar radiation and/or volcanic activities that have been identified as principal causes of this cooling. Methods such as macrofossils, testate amoebae, humification and isotopic analyses coupled with precise dating chronologies (14C and 210Pb) and age models will support the detailed reconstructions of this period characterized by cold climate disturbance and subsequent warming. Results of improved methods will also be integrated into international efforts (Europe, United, other parts of Canada) for amalgamation of various peat databases and development of outputs that will be useful for the PMIP (Paleoclimate Modelling Intercomparison Project) and PCMIP (Paleocarbon Modelling Intercomparison Project) modellers community that respond to the IPPC reports.