Holocene hydro-climatic change and effects on carbon accumulation inferred from a peat bog in the Attawapiskat River watershed, Hudson Bay Lowlands, Canada

2012 ◽  
Vol 78 (2) ◽  
pp. 275-284 ◽  
Author(s):  
Joan Bunbury ◽  
Sarah A. Finkelstein ◽  
Jörg Bollmann
Keyword(s):  
Carbon Accumulation ◽  
Testate Amoeba ◽  
Hudson Bay ◽  
Pollen Record ◽  
Medieval Climate Anomaly ◽  
Northern Ontario ◽  
Peat Core ◽  
Hudson Bay Lowlands ◽  
Isostatic Rebound

AbstractMultiple proxies from a 319-cm peat core collected from the Hudson Bay Lowlands, northern Ontario, Canada were analyzed to determine how carbon accumulation has varied as a function of paleohydrology and paleoclimate. Testate amoeba assemblages, analysis of peat composition and humification, and a pollen record from a nearby lake suggest that isostatic rebound and climate may have influenced peatland growth and carbon dynamics over the past 6700 cal yr BP. Long-term apparent rates of carbon accumulation ranged between 8.1 and 36.7 g C m− 2 yr− 1 (average = 18.9 g C m− 2 yr− 1). The highest carbon accumulation estimates were recorded prior to 5400 cal yr BP when a fen existed at this site, however following the fen-to-bog transition carbon accumulation stabilized. Carbon accumulation remained relatively constant through the Neoglacial period after 2400 cal yr BP when pollen-based paleoclimate reconstructions from a nearby lake (McAndrews et al., 1982) and reconstructions of the depth to the water table derived from testate amoeba data suggest a wetter climate. More carbon accumulated per unit time between 1000 and 600 cal yr BP, coinciding in part with the Medieval Climate Anomaly.

scholarly journals Ecohydrological controls on apparent rates of peat carbon accumulation in a boreal bog record from the Hudson Bay Lowlands, northern Ontario, Canada

2021 ◽  
pp. 1-14
Author(s):  
Marissa A. Davies ◽  
Jerome Blewett ◽  
B. David A. Naafs ◽  
Sarah A. Finkelstein
Keyword(s):  
Accumulation Rate ◽  
Membrane Lipid ◽  
Carbon Accumulation ◽  
Testate Amoeba ◽  
Hudson Bay ◽  
Bacterial Membrane ◽  
Northern Ontario ◽  
Hudson Bay Lowlands ◽  
Poor Fen ◽  
Lipid Biomarker

Abstract A multiproxy Holocene record from a bog in the Hudson Bay Lowlands, northern Ontario, Canada, was used to evaluate how ecohydrology relates to carbon accumulation. The study site is located at a somewhat higher elevation and on coarser grained deposits than the surrounding peatlands. This promotes better drainage and thus a slower rate of carbon accumulation relative to sites with similar initiation age. The rate of peat vertical accretion was initially low as the site transitioned from a marsh to a rich fen. These lower rates took place during the warmer temperatures of the Holocene thermal maximum, confirming the importance of hydrological controls limiting peat accretion at the local scale. Testate amoebae, pollen, and plant macrofossils indicate a transition to a poor fen and then a bog during the late Holocene, as the carbon accumulation rate and reconstructed water table depth increased. The bacterial membrane lipid biomarker indices used to infer paleotemperature show a summer temperature bias and appear sensitive to changes in peat type. The bacterial membrane lipid biomarker pH proxy indicates a rich to a poor fen and a subsequent fen to bog transition, which are supported by pollen, macrofossil, and testate amoeba records.

Linking testate amoeba assemblages to paleohydrology and ecosystem function in Holocene peat records from the Hudson Bay Lowlands, Ontario, Canada

The Holocene ◽  
2020 ◽  
pp. 095968362097279
Author(s):  
David Bysouth ◽  
Sarah A Finkelstein
Keyword(s):  
Water Table ◽  
Trophic Position ◽  
Carbon Accumulation ◽  
Ecosystem Functions ◽  
Testate Amoeba ◽  
Hudson Bay ◽  
Accumulation Rates ◽  
Hudson Bay Lowlands ◽  
Water Tables ◽  
Carbon Accumulation Rates

Peat cores from boreal bog and fen sites in the Hudson Bay Lowlands of Northern Ontario, Canada, were analysed to calculate Holocene carbon accumulation rates, and to show how testate amoeba taxonomic assemblages, inferred depths to water table, and four morpho-traits that may be linked to function (mixotrophy, aperture size, aperture position, and biovolume) changed since peatland initiation. Carbon accumulation rates were on average higher for the Holocene in the fen record (19.4 g C m−2 yr−1) in comparison with the bog record (15.7 g C m−2 yr−1), which underwent a fen-to-bog transition around 6900 cal yr BP. Changes in rates of carbon accumulation were most strongly driven by changes in rates of peat vertical accretion, with more rapid rates in the fen record. Carbon accumulation rates were highest following peatland initiation when reconstructed water tables were highest, and in the late Holocene, when water table positions were variable. Taxa with larger biovolumes and apertures were generally more abundant when reconstructed water tables were higher, most notably following peatland initiation. Mixotrophic taxa were more prevalent in drier conditions and in the bog record. Changing frequencies of morpho-traits suggest that testate amoebae may occupy a higher trophic position in the microbial food web during wetter periods, signaling the possibility of internal feedbacks between peatland ecohydrology and critical ecosystem functions including long-term carbon accumulation.

scholarly journals Bird trends from long-term observation data at sites in the Hudson Bay Lowlands

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Rodney W. Brook ◽  
Lisa A. Pollock ◽  
Kenneth F. Abraham ◽  
Glen S. Brown
Keyword(s):  
Hudson Bay ◽  
Observation Data ◽  
Hudson Bay Lowlands ◽  
Long Term Observation

Lichens on the Hudson Bay Lowlands: a long-term survey in Wapusk National Park, Manitoba

2016 ◽  
Vol 48 (5) ◽  
pp. 581-592 ◽  
Author(s):  
Michele D. PIERCEY-NORMORE ◽  
Irwin M. BRODO ◽  
Chris DEDUKE
Keyword(s):  
Species Diversity ◽  
National Park ◽  
Hudson Bay ◽  
Beach Ridge ◽  
Habitat Types ◽  
Hudson Bay Lowlands ◽  
Coastal Beach ◽  
Physiographic Regions ◽  
Unique Species

AbstractWapusk National Park is part of the Hudson Bay Lowlands in Manitoba and covers 11 475 km2. Lichen surveys were initiated in 2002 but none have reported all species incorporating broad habitat types or a baseline on which to make management decisions. The objectives of this study were: 1) to determine species diversity, including species richness and evenness of the lichens present; 2) to explore species distributions; and 3) to compare lichen growth form and substratum relationships among physiographic regions. Fifty-six locations in four habitat types (physiographic regions: open coastal beach ridge, forested coastal beach ridge, boreal transition forest, and peat plateau bog) and three burned locations were visited over nine years and specimens were collected at each location. A total of 276 species and subspecies were collected. One species is new to Canada (Buellia uberior Anzi) and ten species are new to Manitoba. Species diversity, evenness, and richness were highest in the coastal beach ridge. The open coastal beach ridge, boreal transition forest, and peat plateau bogs formed separate clusters in the non-metric multidimensional scaling (NMS) but the forested coastal beach ridge overlapped with the open coastal beach ridge. Unique species in each region may serve as indicators to monitor long-term changes. While the coastal beach ridge facilitates travel along the coast, it also represents the region with the highest need for intervention to conserve species diversity.

AN AUTOMATIC LEAST‐SQUARES MULTIMODEL METHOD FOR MAGNETIC INTERPRETATION

Geophysics ◽  
1973 ◽  
Vol 38 (2) ◽  
pp. 349-358 ◽  
Author(s):  
Peter H. McGrath ◽  
Peter J. Hood
Keyword(s):  
Least Squares ◽  
Magnetic Anomalies ◽  
Magnetic Data ◽  
Model Parameters ◽  
Hudson Bay ◽  
Northern Ontario ◽  
Magnetic Interpretation ◽  
Hudson Bay Lowlands ◽  
Sverdrup Basin ◽  
Best Fit

The magnetic anomalies caused by such diverse model shapes as the finite strike length thick dike, the vertical prism, thes loping step, the parallelepiped body, etc., may be obtained through an appropriate numerical integration of the expression for the magnetic effect produced by a finite thin plate. Using models generated in this manner, an automatic computer method has been developed at the Geological Survey of Canada for the interpretation of magnetic data. Because the magnetic anomalies produced by the various model shapes are nonlinear in parameters of shape and position, it is necessary to use an iterative procedure to obtain the values for the various model parameters which yield a least‐squares best‐fit anomaly curve to a set of discrete observed data. The interpretation method described in this paper uses the Powell algorithm for this purpose. The procedure can sometimes be made more efficient using a Marquardt modification to the Powell algorithm. Examples of the use of the method are presented for an elongated anomaly in the Moose River basin of the Hudson Bay lowlands in northern Ontario, and for an areally large elliptical anomaly in the Sverdrup basin of the Canadian Arctic Islands.

Holocene carbon accumulation rates from three ombrotrophic peatlands in boreal Quebec, Canada: Impact of climate-driven ecohydrological change

The Holocene ◽  
2011 ◽  
Vol 21 (8) ◽  
pp. 1217-1231 ◽  
Author(s):  
Simon van Bellen ◽  
Michelle Garneau ◽  
Robert K. Booth
Keyword(s):  
Water Table ◽  
Late Holocene ◽  
C Sequestration ◽  
Carbon Accumulation ◽  
Testate Amoeba ◽  
Ecological Processes ◽  
C Cycle ◽  
Sequestration Potential ◽  
Dry Conditions

Understanding the processes controlling peatland carbon (C) sequestration is critical to anticipate potential changes in the global C cycle in response to climate change. Although identification of these factors may be relatively straightforward on seasonal timescales, at centennial to millennial timescales complexities arise because of interactions between climate, vegetation, hydrology and long-term ecological processes. To better understand the factors controlling long-term C accumulation, Holocene rates of C sequestration were quantified from three pristine ombrotrophic peatlands in boreal Quebec, northeastern Canada (52°N, 75–76°W). Bulk density and loss-on-ignition analyses, combined with radiocarbon dating and age–depth modelling, were used to estimate long-term apparent rates of carbon accumulation. Past changes in vegetation and water-table depth were obtained from plant macrofossil and testate amoeba analysis. Earliest regional peat accumulation started ~7520 cal. BP, with long-term rates of C sequestration varying between 14.9 and 22.6 g/m2 per yr. High C sequestration rates occurred during the mid Holocene when relatively stable Sphagnum section Acutifolia communities were present, while low rates were found during the cooler late Holocene when Cyperaceae and ligneous vegetation were more dominant. However, C sequestration was highly variable among cores, implying that local topography, geomorphology and hydrology, or disturbance factors such as fire, mediate the influence of climate on C accumulation. Reconstructed water-table depths reveal several dry shifts since 3000 cal. BP, suggesting that episodic cold and dry conditions during the late Holocene may have contributed to lower C sequestration rates. Given the intensity of the water-table shifts at these times, we hypothesize that recurrent episodes of frozen subsurface peat might have intensified surface drying. As projected by climate scenarios, anticipated warmer and wetter conditions may lead to greater stability of hummock Sphagna cover and increased C sequestration potential in boreal peatlands.

Influence of Holocene permafrost aggradation and thaw on the paleoecology and carbon storage of a peatland complex in northwestern Canada

The Holocene ◽  
2017 ◽  
Vol 27 (9) ◽  
pp. 1391-1405 ◽  
Author(s):  
Nicolas Pelletier ◽  
Julie Talbot ◽  
David Olefeldt ◽  
Merritt Turetsky ◽  
Christian Blodau ◽  
...  
Keyword(s):  
Testate Amoebae ◽  
Carbon Accumulation ◽  
Peat Core ◽  
Creek Watershed ◽  
Temporal And Spatial Variability ◽  
C Stocks ◽  
Temporal And Spatial ◽  
Thawing Permafrost ◽  
Carbon Accumulation Rates

Permafrost in peatlands strongly influences ecosystem characteristics, including vegetation composition, hydrological functions, and carbon cycling. Large amounts of organic carbon are stored in permafrost peatlands in northwestern Canada. Their possible degradation into permafrost-free wetlands including thermokarst bogs may affect carbon (C) stocks, but the direction and magnitude of change are uncertain. Using peat core reconstructions, we characterized the temporal and spatial variability in vegetation macrofossil, testate amoebae, C content, and peat decomposition along a permafrost thaw chronosequence in the southern portion of the Scotty Creek watershed near Fort Simpson, Northwest Territories. The accumulation of limnic and minerotrophic peat prevailed at the site until permafrost formed around 5000 cal. yr BP. Three distinct permafrost periods were identified in the permafrost peat plateau profile, while permafrost only aggraded once in the thermokarst bog profile. Permafrost thawed at ~550 and ~90 cal. yr BP in the thermokarst bog center and edge, respectively. Both allogenic (climatic shifts and wildfire) and autogenic (peat accumulation, Sphagnum growth) processes likely exerted control on permafrost aggradation and thaw. While apparent carbon accumulation rates (ACARs) were lower during present and past permafrost periods than during non-permafrost periods, long-term C accumulation remained similar between cores with different permafrost period lengths. Deep peat was less decomposed in the permafrost plateau compared with the thermokarst bog, which we speculate is due more to differences in peat type rather than differences in decomposition environment between these two ecosystem states. Our study highlights the importance of considering potential deep peat C losses to project the fate of thawing permafrost peat C stores.

scholarly journals Global warming triggers the loss of a key Arctic refugium

2013 ◽  
Vol 280 (1772) ◽  
pp. 20131887 ◽  
Author(s):  
K. M. Rühland ◽  
A. M. Paterson ◽  
W. Keller ◽  
N. Michelutti ◽  
J. P. Smol
Keyword(s):  
Global Warming ◽  
Sea Ice ◽  
Sediment Cores ◽  
Freshwater Ecosystems ◽  
The Arctic ◽  
Hudson Bay ◽  
Native Communities ◽  
Hudson Bay Lowlands ◽  
Short Period

We document the rapid transformation of one of the Earth's last remaining Arctic refugia, a change that is being driven by global warming. In stark contrast to the amplified warming observed throughout much of the Arctic, the Hudson Bay Lowlands (HBL) of subarctic Canada has maintained cool temperatures, largely due to the counteracting effects of persistent sea ice. However, since the mid-1990s, climate of the HBL has passed a tipping point, the pace and magnitude of which is exceptional even by Arctic standards, exceeding the range of regional long-term variability. Using high-resolution, palaeolimnological records of algal remains in dated lake sediment cores, we report that, within this short period of intense warming, striking biological changes have occurred in the region's freshwater ecosystems. The delayed and intense warming in this remote region provides a natural observatory for testing ecosystem resilience under a rapidly changing climate, in the absence of direct anthropogenic influences. The environmental repercussions of this climate change are of global significance, influencing the huge store of carbon in the region's extensive peatlands, the world's southern-most polar bear population that depends upon Hudson Bay sea ice and permafrost for survival, and native communities who rely on this landscape for sustenance.

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