Date of Award
Master of Science (MS)
J. Michael Waddington
Peatlands are an important component of the global carbon cycle, acting as a significant global net sink of carbon dioxide (C02) and are the largest natural source of atmospheric methane (CH4). Peat is also an important resource and has been used as a fuel grade source of energy and for horticultural purposes in various countries for hundreds of years. The Ontario Government recently developed a target to eliminate coal-fired electricity generation by 2014 which has spurred discussions of replacing coal with alternative biomass fuel sources such as peat in northern Ontario power plants such as the Atikokan Generating Station. The aim of this thesis is to determine the impact of extracting peat from a northern Ontario peatland, in order to assess and quantify any potential ecological impacts in relation to (i) vegetation characteristics and functioning and (ii) greenhouse gas (GHG) emissions.
In April, 2008, a paired-catchment experiment was initiated at a northwestern Ontario peatland near Thunder Bay. Peat was extracted from a 12 m by 12 m segment of the experimental site and subsequently reclaimed using the peat block / acrotelm transplant method. The upper 30 cm thick section of the surface vegetation within the experimental plot was removed and set aside briefly prior to peat fuel extraction. Following the removal of approximately 1.5 m in depth of peat, the surface vegetation peat blocks were transplanted back onto the surface of the remaining catotelm in the plot.
Vegetation and greenhouse gas exchange (GHG) measurements were conducted at a nearby control site, the experimental site and a ditch site located alongside the experimental site outflow extraction ditch during the growing seasons of 2008 and 2009 to assess the impacts of extraction on GHG dynamics.
Biodiversity between the control and experimental site did not differ largely in the sampling years, with the ditch hollows displaying the lowest overall levels of plant biodiversity (0.72 Shannon-Weiner Biodiversity Index) in 2009. Despite bare peat being the greatest proportion of late growing season ground cover at the experimental site in both 2008 and 2009, and despite the lack of trees, keystone Sphagnum mosses made up the largest category of living vegetation (30 - 50 %), and had the overall greatest rate of seasonal moss production of all sites. The ditch site had the largest proportion of dead vegetation (77 %), with significantly lower (p < 0.05) production rates of both S. fuscum and S. magellanicum than S. fuscum production rates at the experimental site.
In the first year following extraction GHG fluxes of C02 and CH4 were significantly higher (p < 0.05) at the experimental site than at the control site. By the following year, although Ch4 fluxes increased significantly, fluxes of C02 decreased nearly four times from 7.5 to 1.9 g C02 m-2 d-1, and were no longer significantly different from control site hollows.
Overall the peat block / acrotelm transplant method of peat extraction for the use of peat as a biomass fuel allowed for the rehabilitation of mosses at the experimental site, and prevented any significant overall changes to species cover and biodiversity. As a result of the successful re-establishment of vegetation at the experimental site, overall efflux of C02 was significantly reduced only one year after extraction. Despite increased overall fluxes of CH4 between sampling years it is predicted that GHG fluxes will continue to decrease with time since extraction and rehabilitation.
Wilhelm, Lana P., "Effect of Peat Fuel Extraction and Peatland Reclamation on Vegetation and Greenhouse Gas Exchange" (2010). Open Access Dissertations and Theses. Paper 4167.
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