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

在这个为期5年的提案中提出的研究计划遵循了我在整个全新世期间进行的先例研究活动，提供了关于泥炭起始、泥炭地发育和加拿大东北部北部生物群不同生态区的相关碳积累的原始数据。我们的结果显示了区域全新世碳的时空积累以及不同的季节模式，并证实了长期气候变化作为泥炭地动态和相关碳固定的重要驱动因素所起的作用。在国际社会，最近采取了一些举措，以加强对泥炭堆积的关键气候时期的了解，如新冰期(3000 BP)、中世纪气候异常(350-1200BP)和小冰期(1350-1850 AD)。在北方国家，LIA代表着一个关键时期，因为它在过去几个世纪里影响了永久冻土的堆积。如今，一些残存的永久冻土残留在开阔的北方森林的最北部地区和泰加地区，而景观其他部分的地貌指数表明，它最近正在融化。对近期寒冷异常期的开始、其对泥炭堆积的影响以及受最近变暖影响的最近消失的详细重建，将被用作记录今天加拿大东北部北极变暖的后果的类比。我们打算记录外力的影响，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。宏观化石、遗迹变形虫、腐殖化和同位素分析等方法，加上精确的年代测定(14C和210Pb)和年龄模型，将支持这一时期的详细重建，其特征是气候寒冷扰动和随后的变暖。改进方法的结果也将被纳入国际努力(欧洲、美国、加拿大其他地区)，以合并各种泥炭数据库，并开发将对响应国际气候政策委员会报告的PMIP(古气候模拟对比项目)和PCMIP(古碳模拟对比项目)模型师社区有用的成果。

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.