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

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.

Holocene carbon storage and testate amoeba community structure in treed peatlands of the western Hudson Bay Lowlands margin, Canada

“…Pyxidicula sp. A is also found in abundance in this zone and is associated with Sphagnum moss like other localities in the HBL (Davies et al ., 2021) and adjacent regions (Zhang et al ., 2020a). WTD remains similar to the previous zone (Fig.…”

“…2 and 3), we demonstrate that the main factor causing the differences between the two sites is the presence of Sphagnum moss at the bog site, which generally has lower BD and carbon content than other vegetation types (Loisel et al ., 2014; Packalen et al ., 2016). We also demonstrate that although Sphagnum can promote higher aCARs (Loisel and Bunsen, 2020; Davies et al ., 2021), how the vegetation is preserved is key in determining whether it will lead to increased carbon storage at a given site. At the bog site in this study, the Sphagnum ‐dominated peat between 272 and 188 cm (7430–5860 cal a bp ) had a low BD and was relatively undecomposed compared to the peat intervals above and below.…”

Metabolic and ecological controls on the stable carbon isotopic composition of archaeal (isoGDGT and BDGT) and bacterial (brGDGT) lipids in wetlands and lignites

“…CBTpeat derived pH (Table 2) was stable downcore in all sites, as underlined by their low reconstructed pH standard deviation (Table 2). The exception is James Bay which displayed a significant downcore increase in reconstructed pH (~ 3.8 to 7.8 downcore) (Davies et al, 2021).…”

“…A one to two metre core was collected with a Russian corer from each of these sites: (a) the Everglades site, USA, from Water Conservation Area One (WCA-1) within the Loxahatchee National Wildlife Refuge, with pore water at time of sampling at a near-neutral pH of 6. (Davies et al, 2021). For further details on Sebangau, Tor Royal and the Everglades, see Blewett et al (2020), whilst further details on the James Bay site can be found in Davies et al, (2021).…”

“…(Davies et al, 2021). For further details on Sebangau, Tor Royal and the Everglades, see Blewett et al (2020), whilst further details on the James Bay site can be found in Davies et al, (2021).…”