This study uses life cycle analysis to examine the net greenhouse gas (GHG) emissions from the activities of the peat industry in Canada for the period 1990 to 2000. GHG accounting is undertaken for (1) land use change, (2) peat extraction and processing, (3) the transport of peat to market by truck, train and ship, and (4) the in situ decomposition of extracted peat. The emission estimates were based on results from GHG accounting models using data derived from scientific literature, government and industry statistics, and the responses to a questionnaire sent to Canada's peat establishments. The questionnaire, designed to obtain information on peat extraction methods, land and fuel use, as well as the transportation of peat, had a response rate representing 69% of Canada's total peat production in the year 2000. Results indicate that 540 600 tonnes of greenhouse gases were emitted in 1990 and 893 300 tonnes were emitted in the year 2000 (emission figures are measured in CO2 equivalents using a 100-year time horizon). Peat decomposition was by far the largest source of GHG emissions, averaging 70.6% of total emissions during the eleven-year period from 1990 to 2000. Greenhouse gases from land use change averaged 14.7%. An average of 10.4% of total emissions resulted from the transport of peat to market, while GHGs from extraction and processing averaged 4.3%. Predictions of the annual GHG emissions from the peat industry, assuming a "business as usual" context, were produced for the years 2001 to 2012. These figures were compared with those resulting from various greenhouse gas reduction scenarios.

Global warming, associated with elevated levels of greenhouse gases is expected to alter hydrologic regimes, permafrost extent and vegetation composition in the Hudson Bay Lowlands (HBL). Greenhouse gas (respiration, CH4 and N2O; GHG) emissions and soil gas concentrations were determined over the growing seasons of 2005 and 2006 from numerous habitats within three dominate ecosystems within the HBL, a polygonized-peat plateau, northern fringe boreal forest and palsa fen, near Churchill, Manitoba. Nitrous oxide emissions and soil concentrations were near zero however, a trend for very slight production of N2O was observed at dry aerobic sample positions while very slight consumption occurred at very wet sample locations. “Hot-spots” of intense CH4 emissions and soil concentrations occurred in the sedge-dominated areas of high moisture and plant productivity, whereas areas of low moisture and plant productivity resulted in slight CH4 consumption. Of all the ecosystems studied, the palsa fen had the greatest CH4 production, with carbon losses from CH4 occurring at rates of approximately 50 g C m-2 during the growing season. A peat plateau ecosystem site was also used to compare GHG emissions using a similar vegetation type (Cladina stellaris) and under differing soil conditions. Based on the results, slight gradients in soil conditions such as moisture content, peat accumulation and active layer depths altered respiration emissions but did not significantly affect CH4 and N2O fluxes. The differences in GHG emissions were not as great as those between different plant community types, which suggest plant community types could be used to predict GHG emissions in similar environments.

Daily net ecosystem CO$ sb2$ exchange (NEE) was monitored at several peatland communities in a mid-boreal headwater bog at the Experimental Lakes Area (Kenora, ON., Canada) throughout the 1995-96 growing seasons. Transparent and opaque chamber systems were used to measure NEE and dark respiration at replicate plots in which the vascular vegetation was either clipped or unclipped. CO$ sb2$ fixation and emission fluxes were estimated from NEE measurements and were compared within and among the peatland communities. Communities that supported shrubby, xerophytic vegetation fixed CO$ sb2$ at rates that ranged from, on average, 0.194 to 0.365 mg CO$ sb2$ m$ sp{-2}$ s$ sp{-1}$. These rates did not vary significantly on a daily to weekly timescale, and were comparable in magnitude to the wetter, sedge-dominated communities. CO$ sb2$ emissions varied within and among communities across the sampling season. Rates were, on average, from 0.0568 to 0.109 mg CO$ sb2$ m$ sp{-2}$ s$ sp{-1}$, and the variation was associated with differences in ground temperature and water table. Comparisons of CO$ sb2$ emissions from clipped and unclipped plots allowed an estimation of the contribution of vascular respiration to total CO$ sb2$ emissions. Contributions ranged from 25 to over 80%, depending on the community and season that the measurements were taken. Strong associations between vascular respiration and ground temperature were observed. Daily NEE had little variability between communities and throughout the sampling season. This was attributed to parallel variations for the CO$ sb2$ fixation and emission fluxes. Researchers should quantify the actual fluxes for vascular root respiration, as it possibly controlled a large part of the NEE variability within and between sites.

No description available.

Western boreal peatlands have diverse ground covers of Sphagnum and brown mosses that have important hydrological controls on peatland-atmosphere interactions. Since peatland mosses are non-vascular, their shoot structural morphologies and community growth forms affect the storage and fluxes of water that are critical for maintaining productivity and evaporative functions. While many of the mechanisms of capillary rise are fairly well understood for Sphagnum mosses, there is less information on the water dynamics in communities of Tomenthypnum nitens, a dominant brown moss species in northern rich fens. This study investigated how the different hydrophysical characteristics of moss and peat profiles of T. nitens from a rich fen and intermixed Sphagnum angustifolium and Sphagnum magellanicum, from a poor fen affect capillary flow and water retention to support evaporation and productivity; and how different groundwater and atmospheric sources of water affected these processes. Laboratory investigations indicated volumetric water content and gross ecosystem productivity decrease with water table depth for both mosses without the advent of precipitation, with Sphagnum capitula retaining 10-20% more water than T. nitens due to its moss structure and pore connectivity with the water table. Consequently, Sphagnum capillary rise was sufficient to sustain both high pore-water pressures for evaporation and high water content for productivity at all water table depths due to a gradual shift in average water-retaining pore sizes with depth. The structure of T. nitens moss turfs, consisting of live shoots and a basal layer of old, partially decomposed shoots sometimes overlying well-decomposed peat makes capillary rise more difficult, requiring extremely low matric pressures at the surface, sometimes causing desiccation of the uppermost portions of moss shoots, and hence reduced productivity. Additional nocturnal sources of atmospheric water from dew, distillation, and vapour fluxes provide small, but potentially critical sources of water to rewet desiccated moss shoots for early morning productivity for both T. nitens and Sphagnum mosses. Investigations in the field, however, indicated that with frequent precipitation to rewet the moss and the turf base to refill large pores, evaporative demands at the T. nitens moss canopy could drive capillary flow from the water table to maintain adequate θ for productivity. T. nitens mosses also can grow in turfs disconnected from the underlying iii peat, so that the basal layer temporarily retains water from precipitation for capillary rise. Thus, while capillary connection of the T. nitens moss turf with the underlying peat and water table is not critical to maintain productivity, it grows in a relatively large range of elevations from the water table, compared to Sphagnum and feather mosses. Rewetting of the capitula and the raising of the water table by precipitation provided higher water matric pressures within the moss matrix, and along with high evaporative demands, provided the mechanisms for sufficient capillary flow for productivity. Thus, Sphagnum could grow in habitats far from the water table like feather mosses, although the latter did not require capillary rise for productivity. Furthermore, disequilibrium between water vapour and liquid in the pores of T. nitens in the near-surface suggested pressures calculated with the Kelvin equation may not provide an accurate characterization of actual matric pressures in the moss. However, as the disequilibrium is caused by vapour pressure gradients between the moss and the atmosphere, it is likely a driving factor that helps maintain vapour and capillary water fluxes to provide moisture for T. nitens and other mosses. These results illustrate hydrological mechanisms that explain how moss growth form and habitat are linked. As such, the Sphagnum and T. nitens mosses are well adapted to maintain capillary in their poorly drained habitats in western boreal peatlands.

Global warming, associated with elevated levels of greenhouse gases is expected to alter hydrologic regimes, permafrost extent and vegetation composition in the Hudson Bay Lowlands (HBL). Greenhouse gas (respiration, CH4 and N2O; GHG) emissions and soil gas concentrations were determined over the growing seasons of 2005 and 2006 from numerous habitats within three dominate ecosystems within the HBL, a polygonized-peat plateau, northern fringe boreal forest and palsa fen, near Churchill, Manitoba. Nitrous oxide emissions and soil concentrations were near zero however, a trend for very slight production of N2O was observed at dry aerobic sample positions while very slight consumption occurred at very wet sample locations. “Hot-spots” of intense CH4 emissions and soil concentrations occurred in the sedge-dominated areas of high moisture and plant productivity, whereas areas of low moisture and plant productivity resulted in slight CH4 consumption. Of all the ecosystems studied, the palsa fen had the greatest CH4 production, with carbon losses from CH4 occurring at rates of approximately 50 g C m-2 during the growing season. A peat plateau ecosystem site was also used to compare GHG emissions using a similar vegetation type (Cladina stellaris) and under differing soil conditions. Based on the results, slight gradients in soil conditions such as moisture content, peat accumulation and active layer depths altered respiration emissions but did not significantly affect CH4 and N2O fluxes. The differences in GHG emissions were not as great as those between different plant community types, which suggest plant community types could be used to predict GHG emissions in similar environments.

Approximately 7000 to 8000 years ago when Hudson Bay became ice-free the Tyrrell Sea flooded the Hudson basin and deposited fine grained marine sediments overlaying the previous glacial tills. Coincident with the ablation of the ice sheet isostatic rebound occurred causing regression of the Tyrell Sea and the emergence of a flat, relatively impermeable surface that would eventually host one of the world’s largest wetlands: the Hudson Bay Lowlands. The low permeability marine sediments and low regional slope reduced recharge and runoff, respectively, so that basal tidal marshes were established, and with isostatic up lift were eventually replaced by swamp forests and then forested and non-forested bogs. Recent discovery of kimberlite (diamondiferous) pipes in an area of the lowlands has led the development of an open-pit diamond mine which requires dewatering of the regional aquifer. Dewatering is depressurizing the surrounding Silurian bedrock that underlies the marine sediments. It was hypothesized that these marine sediments would act as a confining layer, isolating the overlying peatlands from the regional bedrock aquifer. We tested this hypothesis by instrumenting a 1.5 km long transect located within the zone of the mine’s influence that crossed various bogs and fens overlying these marine sediments, and was anchored at both ends by bedrock outcrops (bioherms), which represented areas of no marine sediment. Along this transect wells and piezometers were installed within the peat profile and upper marine sediments and bedrock to determine changes in water table and hydraulic head. The exposed bedrock outcrops (bioherms) did act as local drainage nodes, however, this effect was limited to ~30 m, beyond which water tables and hydraulic heads were similar to a control site located 25 km away. However, within this 30 m zone daily losses of water by the enhanced recharge often exceeded those of evapotranspiration (~3mm/day) representing a major local loss of water to the system. It is the distance to bedrock, rather than distance to bioherm, that determines strength of recharge. In areas of thinner marine sediments the daily fluxes were similar (but less) than those in the areas directly surrounding the bioherms, despite being 100s of meters away from the bioherms. The stratigraphy surrounding the bioherms lead to complicated flow regimes with higher conductivity layers (e.g., sands) circumventing the lower permeability marine sediments which may help extend the effect of the bioherms beyond the 30 m distance. The drying peat around the bioherms, and the elevated nature of the bioherms in a flat landscape, put them at increased risk for lighting strikes and thus fires; however, very little viable fuel exists in the peatlands around the bioherms and any fires that might occur would be confined to the bioherm and not spread into the surrounding peatland. Overall, at least within the first 5 years of aquifer dewatering, seasonal weather played the dominant role in affecting the hydrology of the peatlands; a heavy snow pack and cool, wet summer can mask, or at least minimize the effects of aquifer dewatering.

Approximately 7000 to 8000 years ago when Hudson Bay became ice-free the Tyrrell Sea flooded the Hudson basin and deposited fine grained marine sediments overlaying the previous glacial tills. Coincident with the ablation of the ice sheet isostatic rebound occurred causing regression of the Tyrell Sea and the emergence of a flat, relatively impermeable surface that would eventually host one of the world’s largest wetlands: the Hudson Bay Lowlands. The low permeability marine sediments and low regional slope reduced recharge and runoff, respectively, so that basal tidal marshes were established, and with isostatic up lift were eventually replaced by swamp forests and then forested and non-forested bogs. Recent discovery of kimberlite (diamondiferous) pipes in an area of the lowlands has led the development of an open-pit diamond mine which requires dewatering of the regional aquifer. Dewatering is depressurizing the surrounding Silurian bedrock that underlies the marine sediments. It was hypothesized that these marine sediments would act as a confining layer, isolating the overlying peatlands from the regional bedrock aquifer. We tested this hypothesis by instrumenting a 1.5 km long transect located within the zone of the mine’s influence that crossed various bogs and fens overlying these marine sediments, and was anchored at both ends by bedrock outcrops (bioherms), which represented areas of no marine sediment. Along this transect wells and piezometers were installed within the peat profile and upper marine sediments and bedrock to determine changes in water table and hydraulic head. The exposed bedrock outcrops (bioherms) did act as local drainage nodes, however, this effect was limited to ~30 m, beyond which water tables and hydraulic heads were similar to a control site located 25 km away. However, within this 30 m zone daily losses of water by the enhanced recharge often exceeded those of evapotranspiration (~3mm/day) representing a major local loss of water to the system. It is the distance to bedrock, rather than distance to bioherm, that determines strength of recharge. In areas of thinner marine sediments the daily fluxes were similar (but less) than those in the areas directly surrounding the bioherms, despite being 100s of meters away from the bioherms. The stratigraphy surrounding the bioherms lead to complicated flow regimes with higher conductivity layers (e.g., sands) circumventing the lower permeability marine sediments which may help extend the effect of the bioherms beyond the 30 m distance. The drying peat around the bioherms, and the elevated nature of the bioherms in a flat landscape, put them at increased risk for lighting strikes and thus fires; however, very little viable fuel exists in the peatlands around the bioherms and any fires that might occur would be confined to the bioherm and not spread into the surrounding peatland. Overall, at least within the first 5 years of aquifer dewatering, seasonal weather played the dominant role in affecting the hydrology of the peatlands; a heavy snow pack and cool, wet summer can mask, or at least minimize the effects of aquifer dewatering.

Diss. (sammanfattning) Univ. : Linköping, 2001. / Härtill 5 uppsatser.

Thesis (M.S.)--Florida State University, 2004. / Advisor: Dr. Jeffrey P. Chanton, Florida State University, College of Arts and Sciences, Dept. of Oceanography. Title and description from dissertation home page (viewed Sept. 24, 2004). Includes bibliographical references.