Mer Bleue (Fig. 1) was the eastern peatland within the Canadian Carbon Program (http://www.fluxnet-canada.ca ) and an eddy covariance tower operated by Elyn Humphreys (Carleton University) and Peter Lafleur (Trent University) has measured CO2 exchange since 1998 providing an assessment of the seasonal and interannual variability and the influence of changes in climate and water table. Combination of CO2 exchange, CH4 flux and DOC export over 6 years provides an estimate of the interannual variability of the overall C flux in this system (Roulet et al. 2007). The publications and theses of our Mer Bleue are listed below (Mer Bleue Publications and theses:).
Fig. 1. The Mer Bleue peatland in fall and the eddy covariance tower.
My work at MerBleue has involved studies of rates of decomposition of litter and peat (e.g. Scanlon and Moore 2000; Moore et al. 2007), of biomass and plant production and distribution (e.g. Moore et al. 2002; Bubier et al. 2006), of CO2 exchange from chambers covering the range of vegetation types from bog to beaver pond (e.g. Bubier et al. 2003), controls on ecosystem respiration (Lafleur et al. 2006) and the onset of spring photosynthesis in this system (Moore et al. 2006). We have measured CH4 flux at 12 sites over 5 years to define the environmental controls (Moore et al. 2011) and Kerry Dinsmore and Mike Billett (Centre for Ecology and Hydrology, Penicuik, Scotland) have examined fluxes from the beaver ponds (Dinsmore et al. 2009; Billett and Moore 2008). Recent work involves the effect of beaver pond drainage at Mer Bleue on vegetation and CO2 and CH4 fluxes (Ellie Goud, M.Sc. student).
To evaluate the effect of nutrients on the bog, we are conducting a long-term (15-year +) fertilization with N, P and K, and determining plant and CO2 flux response (Fig. 2). Added nutrients enhance shrub growth and shade out mosses, changing the ecosystem structure and CO2 exchange. The ecosystem converts from a sink to a source of CO2 (e.g. Bubier et al. 2007; Juutinen et al. 2010; Larmola et al. 2013). Although there is increased N concentration in shrub leaves and Sphagnum mosses in the fertilized plots, there is a weak response in leaf photosynthesis suggesting that N uptake is stored rather than being in a form enhancing photosynthesis. Nutrient content in foliar tissues varies by species and treatment, with evidence of differential homeostasis between shrubs and mosses (Wang et al. submitted). Nutrient resorption during senescence of shrub leaves is affected by the fertilization and varies among elements (Wang et al. 2014). Ecological stoichiometry determined by PhD student Meng Wang suggests that the vegetation at Mer Bleue is mainly co-limited by N and P. Analysis of peat cores suggests that N is buried along with C but there are mechanisms which keep the P recycling close to the surface (Wang and Moore 2014). PhD student Tanja Zivkovic is establishing rates on N2 fixation at Mer Bleue and examining the possibility of subsurface N2 fixation associated with methanotrophy. MSc student Amanda Alfonso identified the ability of the Mer Bleue vegetation to take up organic N, using dual-labelled glycine and the technique has been applied to species in the restiad bogs of New Zealand.
Fig. 2 The experimental fertilization plots at Mer Bleue.
As part of a broad study of the C dynamics of peatlands in the James Bay region, in collaboration with Nigel Roulet, JukkaTurunen (Geologic Survey of Finland, Kuopio), Michelle Garneau (UQAM) and Pierre Richard (Université de Montréal), M.Sc. student Luc Pelletier measured CO2 and CH4 fluxes from peatlands and small pools (Pelletier et al. 2007, 2011) and Ph.D. student Nicola McEnroe (McEnroe et al. 2009) examined the biogeochemistry of pools in these northern peatlands.
Sampling of ombrotrophic bogs from northwestern Ontario to the Maritimes and their dating with 210Pb has provided an assessment of recent rates of accumulation of C, N and S in peat and the influence of climate and atmospheric N and S deposition (Turunen et al. 2004; Moore et al. 2005). To estimate industrial contaminant deposition, the cores have been analyzed for poly-aromatic hydrocarbons (Christian Blodau and Anna Dryer, University of Bayreuth). The cores have been analyzed for Hg by Brian Branfireun (Western University) to provide a record of the spatial and temporal variation in atmospheric Hg deposition in eastern Canada.In collaboration with John Riley, we have exhumed data contained in a 1980's Inventory of peatlands in Ontario, which involved 400 cores and the collection and analysis of over 1500 individual peat samples. This has provided evidence of stoichiometric patterns of C:N:P:K:Ca:Mg as plant tissues decompose and peat forms in the profile (Wang et al. in press). As with Mer Bleue, large amounts of N are buried, whereas P is recycled, with differences among bogs, fens and swamps. We have also examined patterns of Hg and Pb concentration, which show variations in surface concentration from northwest to southeast Ontario, within which are embedded 'hotpots' associated with population centres and industrial activities.
Litter decomposition and ecological stoichiometry
Rates of litter decomposition in litter-bags over 5 to 6 years have been determined at several peatland sites across eastern Canada (e.g. Schefferville QC, Sept-Iles QC, Mont St Hilaire QC, Mer Bleue ON and Experimental Lakes Area, ON). Controls of litter chemistry and site have been established (Moore et al. 2007) and a synthesis from all sites is being prepared.
Fig. 3. Peatlands for litter decomposition studies, North Island, New Zealand.
Fig. 4. The pocosin peatlands, coastal North Carolina, used for litter decomposition studies.
Near Rivière du Loup (QC) and Shippagan (NB), we have examined the effect of drainage and harvesting of peat moss on the C cycle and whether vegetation restoration practices can bring back the peat to C cycling function similar to that before the peat was disturbed. Post-doctoral Fellow Stephan Glatzel (now University of Rostock, Germany) showed the variation in CO2 and CH4 production potentials of peats at these sites (Glatzel et al. 2004), and the patterns of porewater DOC and influence on CO2 emission rates (Glatzel et al. 2003). M.Sc. student Michele Marinier determined the influence of cotton-grass on CO2 and CH4 fluxes (Marinier et al. 2004). We are currently preparing a manuscript examining changes in gas fluxes from natural peatlands through drainage and harvesting to restoration. Ph.D. student Nate Basiliko (now University of Toronto) determined the potential of peat natural, harvested and restored to exchange CH4 and CO2 and the controls on these potentials (Basiliko et al. 2007). M.Sc. student Julian Cleary performed a C life-cycle analysis of the Sphagnum-peat industry in Canada (Cleary et al. 2005).
Fig. 5. Peatland restoration in eastern Quebec and New Brunswick.
Detection of graves
As part of a SSHRC-sponsored project on the detection of clandestine graves led by Margaret Kalacska, Mike Dalva and examined patterns of CH4 emission from soils in an animal graveyard of Parc Safari Africain, near Hemmingford, QC. Graves emit large amounts of CH4 to the atmosphere, sampling of the [CH4] in the atmosphere just above the soil surface at dawn after a still night reveals the patterns of graves and the soils around graces show high rates of both CH4 production and consumption (Dalva et al. 2012). Follow-up work has involved cows buried in Costa Rica and pigs buried near Ottawa. In both cases, CH4 patterns were not related to graves, but N2O concentrations and fluxes were higher around buried carcasses (Dalva et al. 2015).
Methane and nitrous oxide fluxes from Canadian forests
A three-year CFCAS and BIOCAP grant allowed the determination of CH4 and N2O exchange between forest soils and the atmosphere. Sites included the Turkey Point ON (AltafArain, McMaster University), Chibougamau QC (Hank Margolis, Univesité Laval) Canadian Carbon Program sites, plus sites in northern Quebec and Mont St. Hilaire and Morgan Arboretum, near Montreal, directed by Research Associate Sami Ullah (now Universities of Lancaster and Keele, UK). The magnitude and controls on the fluxes of these two greenhouse gases has been established (Peichel et al. 2010; Ullah et al. 2009; Ullah and Moore 2009, 2011). In addition, laboratory studies have identified microbial and biogeochemical controls on fluxes (Ullah et al. 2008; Frasier et al. 2010). A synthesis of greenhouse gas fluxes in Canadian forest soils is being prepared.
Dissolved organic carbon (DOC) in forests
We examined the role of DOC in C cycling within upland forests, supported by BIOCAP and NSERC. Measurements were made of field DOC fluxes, and laboratory experiments performed on DOC production, biodegradability, sorption and chemistry and modelling (Ph.D. students Julie Turgeon and Dolly Kothawala). Sources, sinks and fluxes of DOC were made at the Turkey Point ON (Peichl et al. 2007) and Campbell River BC Fluxnet sites. Sorption studies revealed the importance of mineral soil chemistry on DOC and N sorption (Kothawala et al. 2008, 2009) and DOC production studies revealed the importance of DOM chemistry and temperature (Moore et al. 2008).
Soil carbon and land-use change
I have become involved in broader issues of carbon sequestration in soils, particularly in response to land-use change. In 2001 in Sardinilla, Panama, a large old pasture was converted to a native tree plantation by Catherine Potvin (Biology, McGill) in collaboration with the Smithsonian Tropical Research Institute. M.Sc. student Muriel Abraham determined the pattern of soil characteristics using geo-statistical techniques for the surface layers (0-10 cm) as well as the soil profile. Changes in C cycling and the role of biodiversity have been noted (e.g. Potvin et al. 2004, 2011). The site soils were resampled in June 2011 to provide a well-controlled study of the changes in soil C and N and the origin of organic matter (through changes in δ13C) brought about by the land-use change. The change from forest pasture decreased soil organic C and N content and mass, and the conversion to native tree plantation has reversed this trend, with concomitant changes in the proportion of C3 and C4 plants contributing to the soil organic matter.
Fig. 6. The old pasture at Sardinilla, Panama, in 2001 and part of the native tree plantation, 2011.
Member of Global Environmental and Climate Change Centre
Department of Geography
Last updated 21/11/2011