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Session Overview

Wednesday, April 06

Session de l'après-midi partie 1 / Afternoon session part 1


Room: Hydro-Québec
13:30 Peatland ecosystems: leaders in terrestrial carbon storage
* Michelle Garneau, Department of geography, Geotop and GRIL Research Centers, Université du Québec à Montréal, Canada
Joannie Beaulne, Département Science et Technologie, Université TÉLUQ, Canada
Gabriel Magnan, Geotop and GRIL Research Centers, Université du Québec à Montréal, Canada

The C sequestration potential of forested peatlands has been quantified and showed that peat horizons store more carbon than tree aboveground and belowground biomass over the same period of time.

14:00 Ecohydrology of natural and constructed ecotones surrounding peatlands in south eastern Manitoba
* Frank Yamoah, Brandon University, Canada
Pete Whittington, Brandon University, Canada

Ecotones are dynamic communities between two ecosystems that ensure the exchange of water, energy and nutrients and are typical between natural bogs and fens. Integrating this concept during the restoration of extracted peatlands and their natural surrounding is not common practice, in part to not being well understood. One recent approach to restore ecotone function is to create slopes on the periphery of the extracted peatland. Water table, surface elevation, peat depth and moisture content (5 m interval) were determined across 8 identified transects on an extracted peatland in South-eastern Manitoba in 2019 (pre-restoration) and re-established in 2020 (post-restoration). Water retention strategies were included within the slopes to improve the hydrological connection (5-Pond, 3-Pond, Berm and Control) at three sections (West, Northwest and South) of the site. Surface elevation across 3 of the 8 transects dropped by ~1 m within 20m of the peripheral ditch. Water tables increased by 31.3 cm after reprofiling across the 3 out of the 8 transects. Average water table across all 8 transects in 2019 (May – August) was -72.3 ± 54.2 cm and in 2020 (May – August) was -36.7 ± 50.0 cm. Ponds and berms were generally effective at improving hydrological condition on the ecotone slopes. Soil moisture content increased immediately following rain events. Combining the water retention technique used in the study with surface reprofiling along artificial ecotone slopes can be effective at improving hydrological conditions, thus increasing the success of restoration.

14:15 The water balance of a previously vacuum extracted bog restored to a fen in South-Eastern Manitoba
* Haley Lobreau, Brandon University, Canada
Pete Whittington, Brandon University, Canada
Scott Ketcheson, Athabasca University, Canada

Prompt and active restoration of extracted peatlands back to a carbon accumulating ecosystem is a key component in the sustainable management of growing media. Water availability is usually the limiting factor of success, thus quantifying the water balance is critical to understanding new restoration methods, especially in regions where water availability is of particular concern, such as Manitoba. Typically, harvested peatlands are restored to bogs, but in Manitoba there has been a recent effort to restore to fens. Three different surface re-contouring techniques were used: finished (flat, two passes with bulldozer), in-progress (bunds created from one pass with the bulldozer) and remnant (no passes, left untouched after extraction), each instrumented with wells, piezometers, lysimeters, and tensiometers. Evaporation is the dominant water loss from the system with an average loss of 4.6 and 3.2 mm/day from May to August 2020 and 2021, respectively, ranging between (min, 1.1 mm/day) and (max, 4.0 mm/day) in 2021. In spite of re-contouring restoration efforts, the water table dropped more than a meter below the surface, resulting in very low soil water pressure (-28.3 mb in May to as low as -334 mb in July, with an average of -124 mb from May to August 2021) and conditions too dry to support fen bryophyte vegetation. By understanding the magnitude and distribution of water fluxes across the different restoration techniques, restoration efforts can be modified to reduce major water losses in future planning.