Michelle Garneau results 17
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Peat profile database from peatlands in CanadaNARA Subscribed
Peatlands cover approximately 12% of the Canadian landscape and play an important role in the carbon cycle through their centennial‐ to millennial‐scale storage of carbon under waterlogged and anoxic conditions. In recognizing the potential of these ecosystems as natural climate solutions and therefore the need to include them in national greenhouse gas inventories, the Canadian Model for Peatlands module (CaMP v. 2.0) was dev...
Climate warming is leading to permafrost thaw in northern peatlands, and current predictions suggest that thawing will drive greater surface wetness and an increase in methane emissions. Hydrology largely drives peatland vegetation composition, which is a key element in peatland functioning and thus in carbon dynamics. These processes are expected to change. Peatland carbon accumulation is determined by the balance between pla...
Widespread recent ecosystem state shifts in high‐latitude peatlands of northeastern Canada and implications for carbon sequestrationNARA Subscribed
Northern peatlands are a major component of the global carbon (C) cycle. Widespread climate‐driven ecohydrological changes in these ecosystems can have major consequences on their C sequestration function. Here, we synthesize plant macrofossil data from 33 surficial peat cores from different ecoclimatic regions, with high‐resolution chronologies. The main objectives were to document recent ecosystem state shifts and explore th...
Testate amoebae are abundant in the surface layers of northern peatlands. Analysis of their fossilized shell (test) assemblages allows for reconstructions of local water‐table depths (WTD). We have reconstructed WTD dynamics for five peat cores from peatlands ranging in distance from the Athabasca bituminous sands (ABS) region in western Canada. Amoeba assemblages were combined with plant macrofossil records, acid‐insoluble as...
Dust deposited on two ombrotrophic peat bogs (Baie and IDH bogs) of the St. Lawrence Gulf and Estuary north shore (Quebec) was geochemically characterized using rare earth element (REE) concentrations, Nd and Pb isotopes along with particle grain size. Both cores display similar ɛNd values, which suggests either a common source or sources with similar signatures in both regions. Combining Nd isotope data with REE patterns and...
Proxy records of late Holocene relative sea‐level changes are important for our understanding of mechanisms that drive contemporary sea‐level trends. In the Gulf of Saint Lawrence (eastern Canada), the Magdalen Islands currently experience higher than global average rates of relative sea‐level rise. This article presents original reconstruction data of sea‐level changes from the Magdalen Islands over the past few millennia col...
This 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 w...
Poor fen succession over ombrotrophic peat related to late Holocene increased surface wetness in subarctic Quebec, CanadaNARA Subscribed
Northern peatlands act as archives of environmental change through their sensitivity to water balance fluctuations, while being significant contributors to global greenhouse gas dynamics. Subarctic fens in north‐eastern Canada are characterized by a dominance of pools and flarks. We aimed to reconstruct the late Holocene hydrological conditions of these fens to establish the timing of the initiation of pool and flark formation...
Proxy reconstructions of climatic parameters developed using transfer functions are central to the testing of many palaeoclimatic hypotheses on Holocene timescales. However, recent work shows that the mathematical models underpinning many existing transfer functions are susceptible to spatial autocorrelation, clustered training set design and the uneven sampling of environmental gradients. This may result in over‐optimistic pe...
Local versus regional processes: can soil characteristics overcome climate and fire regimes by modifying vegetation trajectories?NARA Subscribed
We analysed charcoal and pollen from sediments obtained from two lakes in the northwestern mixed‐wood Canadian boreal forest in order to reconstruct fire‐return intervals and vegetation dynamics over the last 8000 years. Sites were selected with contrasting soil properties (mesic versus dry‐sandy soils), allowing an estimation of the potential influence of soils on long‐term vegetation and fire dynamics. The sites likely exper...
Modern Sphagnum δ 13 C signatures follow a surface moisture gradient in two boreal peat bogs, James Bay lowlands, QuébecNARA Subscribed
Carbon isotopic composition of Sphagnum macrofossils can potentially be used as a palaeohydrological tool for peat‐based climatic studies since a relationship between Sphagnum δ 13 C values and peatland surface moisture has been presented in previous studies. In order to verify this hypothesis, modern Sphagnum δ 13 C values were measured along a moisture (microtopographic) gradient in two boreal peat bogs. Isotopic measurement...
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