Evaluating long‐term regional climate variability in the maritime region of the St. Lawrence North Shore (eastern Canada) using a multi‐site comparison of peat‐based paleohydrological records

Abstract

ABSTRACTThis study presents paleohydrological reconstructions from ombrotrophic peatlands (bogs) along the north shore of the Estuary and the Gulf of St. Lawrence in eastern Canada. Past water table depths were reconstructed based on testate amoebae analyses within four peatlands from two maritime ecoclimatic regions (boreal and subarctic) using a new transfer function. The comparison of multiple peat‐based paleohydrological records was used to distinguish climate‐driven changes from variations related to site‐specific factors. Coherence between the water table reconstructions at the regional scale suggests a common climatic influence on bog paleohydrology but there are inconsistencies which also suggest an influence of non‐climatic factors (e.g. internal peatland processes and feedbacks). The surface drying and increased hydrological variability after 3000 cal a BP in the studied bogs coincide with the transition from the Holocene Climatic Optimum to the Neoglacial cooling documented by proxy climate records in eastern Canada. The bogs of Havre St‐Pierre have experienced major drying during the late Holocene, indicating important annual‐to‐centennial water deficits at the peatland surface. Regional differences in the magnitude of the hydrological fluctuations may result from distinctive climatic conditions or could indicate that bog surface wetness in the Gulf of St. Lawrence was more sensitive to past climate changes.