Peatland In Ontario Research Articles

The impact of severe pollution from smelter emissions on carbon and metal accumulation in peatlands in Ontario, Canada

Peatlands are unique habitats that function as a carbon (C) sink and an archive of atmospheric metal deposition. Sphagnum mosses are key components of peatlands but can be adversely impacted by air pollution potentially affecting rates of C and metal accumulation in peat. In this study we evaluate how the loss of Sphagnum in peatlands close to a copper (Cu) and nickel (Ni) smelter in Sudbury, Ontario affected C accumulation and metal profiles. The depth of accumulated peat formed during the 100+ year period of smelter activities also increased with distance from the smelter. Concurrently, peat bulk density decreased with distance from the smelter, which resulted in relatively similar average rates of apparent C accumulation (32–46 g/m2/yr). These rates are within the range of published values despite the historically high pollution loadings. Surface peat close to the smelters was greatly enriched in Cu and Ni, and Cu profiles in dated peat cores generally coincide with known pollution histories much better than Ni that increased well before the beginning of smelter activities likely a result of post-deposition mobility in peat cores.

Drivers of decomposition and the detrital invertebrate community differ across a hummock-hollow microtopology in Boreal peatlands

ABSTRACTIn boreal peatlands, low decomposition rate is the underlying cause of carbon sequestration. Decomposition of litter can be affected by factors relating to soil moisture and temperature, the quality of the litter, and by the biotic decomposer community, among others. Exploring how these drivers interact will provide better understanding of carbon dynamics in boreal peatlands. We measured the decomposition of three common peatland plant functional types (moss, sedge, shrub), and associated microarthropod communities using litterbags placed in hollows (wet depressions) and hummocks (dry, raised areas) of a boreal peatland in Ontario, Canada. Decomposition was significantly different between all plant litter types, and greatest in sedge, but was not significantly different between hummock and hollow microhabitats. The decomposer community displayed an opposite pattern, significantly affected by microhabitat where richness and abundance of microarthropods was greater in hollows than hummocks. Oribatid mites were the dominant microarthropod with respect to both richness and abundance. Plant litter type did not affect community structure in hollows, but was a determinant of oribatid dominance in hummocks. These results suggest that abiotic environmental conditions are the main drivers of community structure for decomposers, while plant litter quality is a more important determinant of decomposition dynamics in boreal peatlands.

Distribution of lead and mercury in Ontario peatlands

While considerable attention has been given to the measurement of mercury (Hg) and lead (Pb) concentrations and accumulation in detailed peat cores in central Canada, the geographic distribution and density of sampling are generally limited. Here, we use the Ontario Peatland Inventory to examine broad patterns of Hg and Pb concentration with depth, based on 338 peat cores (containing >1500 analyzed samples) from 127 bogs, fens and swamps located in southeastern, northeastern and northwestern sections of Ontario. Overall, Hg concentrations averaged 0.05 μg g−1 and that of Pb averaged 10.8 μg g−1. Maximum values in the top 50 cm of the profiles are 0.08 μg g−1 and 26.2 μg g−1 for Hg and Pb, respectively. The ratio between these values (surface) and the values from below 100 cm (background), where peat likely accumulated before 1850 and industrial activities were limited, are 2.3 and 6.6 for Hg and Pb, respectively. The highest surface:background concentration ratios are generally found in the westernmost part of the province and in the southeast for Hg and around areas that are more heavily populated for Pb. Our results show that a vast amount of Hg and Pb are stored in Ontarian peatlands, although the spatial distribution of these stores varies. The rapid decomposition of peat in a changing climate could release these pollutants to the atmosphere.

Predicting peatland carbon fluxes from non‐destructive plant traits

Summary Determining the plant traits that best predict carbon (C) storage is increasingly important as global change drivers will affect plant species composition and ecosystem C cycling. Despite the critical role of peatlands in the global C cycle, trait–flux relationships in peatlands are relatively unknown. We assessed the ability of four non‐destructive plant traits to predict carbon dioxide (CO2) and methane (CH4) fluxes over two growing seasons in a temperate peatland in Ontario, Canada. We examined relationships between C‐fluxes and leaf area, leaf persistence (deciduous, evergreen), growth form (woody, herbaceous) and aerenchyma tissue. To explore potential inconsistencies between different scales of data aggregation, traits were analysed at the level of plots, species and microsites. CO2 fluxes showed a positive relationship with leaf area and leaf persistence, and a negative relationship with proportion of woody species. CH4 fluxes showed a positive relationship with aerenchyma and leaf area. The significance of trait–flux relationships differed based on whether data were averaged at the level of plot, species or microsite. We recommend applying leaf area as a non‐destructive trait to other systems where it is not ideal to measure traits destructively. A better understanding of the relationships between above and below‐ground traits is likely needed to further explain variation in ecosystem respiration and CH4 fluxes from plant traits. A lay summary is available for this article.

Re-assessing the vertical distribution of testate amoeba communities in surface peats: Implications for palaeohydrological studies

Testate amoeba-derived transfer functions are frequently used in peatland palaeohydrological studies and involve the development of training sets from surficial peats. However, within acrotelmic peats, considerable vertical variation in assemblage composition can occur, particularly along Sphagnum stems, which may limit the representation of the associated ‘contemporary’ testate amoeba samples as analogues for the peatland surface. This paper presents contiguous testate amoeba assemblage data from nine monoliths collected from different peatland microforms (hummock, hollow, lawn) in three Sphagnum dominated ombrotrophic peatlands in Ontario and Quebec, eastern Canada. The aim is to: (i) gain a greater understanding of the vertical distribution of xerophilous/hygrophilous taxa along Sphagnum stems; (ii) determine the vertical extent of live/encysted taxa along this gradient; and (iii) assess the significance of this distribution on surface sampling protocols. The results show that testate amoeba communities in the uppermost acrotelmic peat layers display considerable variability. This may reflect a complex interplay of abiotic and biotic controls, including moisture, temperature, light and other characteristics, food availability, and mineral particle availability for test construction. These findings underline the complexity of testate amoeba community structure and highlight the importance of analysing both living and dead Sphagnum stem sections when developing calibration sets.

An individual-tree basal area growth model for black spruce in second-growth peatland stands

A basal area growth model was developed to predict the growth of individual trees in second-growth black spruce (Picea mariana (Mill.) BSP) stands on northeastern Ontario peatlands. The data were derived from stem analysis trees collected in 1985 and 1986 from stands harvested 47-68 years earlier. For a period starting from the date of data collection and going back to 10 years from the harvesting, tree basal area growth, diameters, and stand characteristics were retrospectively calculated at 5-year intervals. To estimate previous mortality, self-thinning relationships for black spruce were applied. In the model, 5-year basal area growth of a tree was expressed as a function of tree diameter, stand-level competition, tree-level competition, and peat thickness. There was considerable change in the growth-size relationship over time. A random parameter approach was applied in model construction to account for the spatial and temporal correlations of the observations. The proposed model explicitly incorporates factors normally included in a "random error" term and, therefore, should provide more sensitive tests of the contributions of the various factors to growth prediction. The estimated model showed only slight bias against the modeling data and the predicted stand basal area development was comparable with that given in other studies.

The accumulation of cadmium by the yellow pond lily, Nuphar variegatum, in Ontario peatlands.

Cadmium concentrations of a common macrophyte, the yellowpond lily (Nuphar variegatum) were investigated from peatlands with arange in pH (4.4-6.3), alkalinity (0-181 microeq/L Ca), DOC (5.1-16.8 mg/L), and sediment organic content (20-88%). Cd concentrations inNuphar ranged from 0.3 to 1.51 microg/g in the leaves and from 0.46 to1.51 microg/g in the petioles, and was significantly higher in the petiolesthan in the leaves (p = 0.014; t-Test). Significant and negativecorrelations between Nuphar leaf Cd and pH (r2 =0.76; p < 0. 001), alkalinity (r2 = 0.41; p =0.034), and DOC (r2 = 0.46; p = 0. 022) wereobtained. In addition, a significant and negative correlation was foundbetween Nuphar petiole Cd and pH (r2 = 0.46; p= 0.023). These results indicate that the leaves of Nupharfound in peatlands of low pH, low alkalinity, and low DOC, and the petiolesof Nuphar found in peatlands of low pH are more susceptible toaccumulating potentially toxic levels of Cd. The organic content of thepeatland sediments was not significantly correlated with either the leaf orpetiole Cd concentration. Nuphar is an important food source for manywetland animals; any Cd that is present in these plants may be passed ontoother trophic levels because diet is considered to be the major source of Cdto animals.

Base cation composition of pore water, peat and pool water of fifteen Ontario peatlands: Implications for peatland acidification

Base cation (Ca, Mg, Na, K) concentrations in surface waters, pore waters and surface peats were determined along a mineral-poor to mineral-rich fen gradient for 15 south-central Ontario peatlands. Surface waters of the peatlands ranged in pH and alkalinity from 4.5 to 6.3 and 0 to 181μeqL−1, respectively. Both surface water and pore water Ca and Mg concentrations followed the expected decrease along the mineral-rich to poor-fen gradient. Surface water concentrations of Ca and Mg were significantly lower in the mineral-poor versus the moderately-poor and mineral-rich fens (P<0.05, ANOVA). Pore water concentrations of base cations were 3–5 fold less in mineral-poor vs. mineral-rich fens. In contrast to surface and pore waters, peat base cation concentrations did not decrease along the mineral-rich to mineral-poor fen gradient. Surface peat base cation concentrations were also independent of pore water cation concentrations, and local bedrock geology. Relative concentrations of base cations in surface peats of all peatlands were best described by the exchangeable cation capacity of the surrounding soils.

FLOW REVERSALS IN PEATLANDS INFLUENCED BY LOCAL GROUNDWATER SYSTEMS

Piezometric head data from various depths were examined at two peatlands in Ontario, Canada and one peatland in Sweden influenced by small-scale, shallow groundwater systems. Data from different hydrogeological settings show reversals in groundwater flow leading to discharge in topographically high regions of peatlands in isolation from large-scale groundwater flow. It is suggested that subsurface flow within peat can reverse in direction in response to water deficit and water-table drawdown. The data presented here refute the assumption that local groundwater flow in peatlands is unidirectional and further illustrate the fact that measurable subsurface water flow can occur at depth in peat isolated from large-scale groundwater flow systems. In the light of implicit assumptions made by many workers on water movement in peatlands, especially when connected to small-scale groundwater systems, the consequences of such reversals are paramount in understanding the hydrology and biogeochemistry of peatlands. © 1997 by John Wiley & Sons, Ltd.

A study of the geoelectrical properties of peatlands and their influence on ground‐penetrating radar surveying1

AbstractGeophysical surveys and chemical analyses on cores were carried out in three Ontario peatlands, from which we have gained a better understanding of the peat properties that control the geophysical responses. The electrical conductivity depends linearly on the concentration of total dissolved solids in the peat pore waters and the pore waters in turn bear the ionic signatures of the underlying mineral sediments. The ionic concentration, and thus the electrical conductivity, increase linearly from the surface to basement. The average bulk electrical conductivity of peatlands at Ellice Marsh, near Stratford, and at Wally Creek Area Forest Drainage Project, near Cochrane, are of the order of 25 mS/m. The Mer Bleue peatland, near Ottawa, has extremely high electrical conductivity, reaching levels of up to 380 mS/m near the base of the peat. The Mer Bleue peatland water has correspondingly high values of total dissolved solids, which originate from the underlying Champlain Sea glaciomarine clays. The dielectric permittivity in peats is largely controlled by the bulk water content. Ground penetrating radar can detect changes in water content greater than 3%, occurring within a depth interval less than 15 cm. The principal peatland interfaces detected are the near‐surface aerobic to anaerobic transition and the peat to mineral basement contact. The potential for the successful detection of the basement contact using the radar can be predicted using the radar instrument specifications, estimates of the peatland depth, and either the bulk peat or the peat pore water electrical conductivities. Predicted depths of penetration of up to 10 m for Ellice Marsh and Wally Creek exceed the observed depths of 1 to 2 m. At Mer Bleue, on the other hand, we observe that, as predicted, a 100 MHz signal will penetrate to the base of a 2 m thick peat but a 200 MHz signal will not.

Methane flux from drained northern peatlands: Effect of a persistent water table lowering on flux

Measurements of CH4 flux from drained and undrained sites in three northern Ontario peatlands (a treed fen, a forested bog, and a treed bog) were made from the beginning of May to the end of October 1991. In the drained portions, the water table had been lowered between 0.1 and 0.5 m, compared to the water table of the undrained portion of the peatlands. The mean seasonal CH4 flux from the undrained portions of three peatlands was small, ranging from 0 to 8 mg m−2d−1, but similar to the CH4 flux from other treed and forested northern peatlands. The mean seasonal CH4 flux from the drained portion of the peatlands was either near zero or slightly negative (i.e.,uptake): fluxes ranged from 0.1 to −0.4 mg m−2 d−1. Profiles of CH4 in the air‐filled pores in the unsaturated zone, and the water‐filled pores of the saturated zone of the peat at the undrained sites, showed that all the CH4 produced at depth was consumed within 0.2 m of the water table and that atmospheric CH4 was consumed in the upper 0.15 m of the peatland. On the basis of laboratory incubations of peat slurries to determine CH4 production and consumption potentials, the lowering of the water table eliminated the near‐surface zone of CH4 production that existed in the undrained peatland. However, drainage did not alter significantly the potential for CH4 oxidation between the water table and peatland surface but increased the thickness of the layer over which CH4 oxidation could take place. These changes occurred with a drop in the mean summer water table of only 0.1 m (from −0.2 to −0.3 m) suggesting that only a small negative change in soil moisture would be required to significantly reduce CH4 flux from northern peatlands.

Oxygen-18 Composition of Sphagnum, and Microenvironmental Water Relations

The 180 isotope content of Jive species of Sphagnum from three peatlands in Ontario was analyzed. Sphagnum fuscum and S. capillifolium had significantly more enriched 6'80 values than S. fallax, S. magellanicum, and S. papillosum. The enriched values in the former species indicate that water involved in photosynthesis in hummock species is much more affected by evapotranspiration than in adjacent species situated in depressions. These data suggest that microenvironmental water relations regulate evapotranspiration in Sphagnum species. Environmental isotope analysis (180, 2H) is another technique that may shed light on understanding Sphagnum ecophysiology and water relations along microenvironmental gradients in northern peatlands. The vertical distribution of Sphagnum species along microtopographic gradients has long been noted, indeed, ever since the earliest ecological studies of northern bogs and poor fens (Andrus et al. 1983; Clymo & Hayward 1982; Sj6rs 1948; Vitt et al. 1975). The genus Sphagnum represents a unique group of hydrophytes especially adapted to periodic drought conditions because of large seasonal changes in water supplies reaching peatland surfaces. Ecological factors such as cation exchange capacity, desiccation resistance, water holding capacity, degree of drying, and photosynthetic ability have been found to be important for Sphagnum microenvironmental distribution patterns (Andrus 1986; Clymo & Hayward 1982; Lindholm 1990). Environmental isotopes--oxygen18 (180) and deuterium (2H)-that form part of the water molecules and organic compounds in plant organic matter, have been widely used in ecology and geochemistry (Fritz & Fontes 1980; Rundel et al. 1989). One specific application is in the reconstruction of paleoclimate based on the isotopic composition of fossil wood and peat cellulose (Dupont & Brenninkmeijer 1984; Edwards et al. 1985; Yapp & Epstein 1982). Paleoclimatic inferences are based on the relationship between the 180 and 2H composition of plant cellulose and the isotopic composition of the plant water source and relative humidity (Burk & Stuiver 1981; DeNiro & Epstein 1979; Epstein et al. 1977). We report some results of a project aimed at assessing the relationship between the isotopic composition of bog plant species and environmental factors. The understanding of this relationship is essential if stable isotopes in fossil peat plant cellulose are to be used in paleoclimate studies. This paper proposes that isotopic analysis of Sphagnum mosses may be an important aid in understanding the ecophysiological requirements and microenvironmental distribution of sphagna. MATERIAL AND METHODS Field methods.--Mosses for this study were collected from three peatlands in Ontario. Oliver's Bog is a floating bog and fen complex (sensu Tarnocai et al. 1988) developed in a closed kettle basin 4 km southeast of Cambridge in southwestern Ontario (43019'45N; 80017'15W). An open bog and poor fen mat has a soft bottom closest to the open water area in the centre and is firmly anchored in the treed bog area around the edge of the basin. The mat portion, where mosses were collected for this study, is characterized by oligotrophic lawn and carpet vegetation with some areas periodically in contact with waters of the underlying lake system, and having small ombrotrophic hummocks. Emo Bog is a large ombrotrophic raised bog complex, about 680 ha in size, situated 8 km northeast of Emo in northwestern Ontario, near the Minnesota-Ontario border (48042'N; 93047'W). It is a forested-low shrub bog with Picea mariana, numerous ericaceous shrubs, and welldeveloped hummock microtopography. Rainy River Bog is 40 km west of Emo Bog and 6 km north of the Town of Rainy River (48047'30N; 94034'W). This ombrotrophic bog is developed in a small basin about 10 ha in size with a vegetation cover and microtopography similar to that at Emo Bog. Laboratory procedures. -Representative Sphagnum mosses were collected at each study site for isotope analyses in June or July 1987. Samples that included several moss stems were selected from adjacent paired microsites-hummock top and a position near the bottom of the side of the hummock. Sphagnum nomenclature follows Anderson (1990). Voucher specimens are deposited in the Wetlands Ecology Laboratory at the University of Waterloo. Cellulose was extracted from the living plants 0007-2745/92/445-448$0.55/0 This content downloaded from 157.55.39.54 on Fri, 01 Jul 2016 05:38:50 UTC All use subject to http://about.jstor.org/terms 446 THE BRYOLOGIST [VOL. 95 TABLE 1. Isotopic composition of Sphagnum from three peatlands in Ontario. The sample of S. magellanicum from Emo bog may contain some Polytrichum strictum. Collection sites: OB = Oliver's Bog, a quaking bog, southwestern Ontario; RRB = Rainy River Bog, a raised basin bog, northwestern Ontario; EB = Emo Bog, a raised basin bog, northwestern Ontario; SMOW = standard mean ocean water.

Economic evaluation of forest drainage and fertilization in northern Ontario peatlands with an investment decision model

Drainage and fertilization of an existing peatland black spruce (Picea mariana (Mill.) B.S.P.) stand and 24 possible methods of planting a clear-cut area near Cochrane, Ontario were evaluated by means of a recently developed forestry investment decision model, “FIDME”.

COMPARISONS OF METHODS OF pH DETERMINATION FOR ORGANIC TERRAIN SURVEYS

pH values were measured on peat samples taken from a water-logged peatland in Ontario, from April 1970 to April 1971, by 14 procedures: on fresh peat and groundwater, in their natural state; and on combinations of hand-squeezed, air-dried, and oven-dried peat, each rewetted to liquid limit with either distilled H2O, N/100 CaCl2∙2H2O, N/10 KCl, or N/10 CaCl2∙2H2O. Groundwater showed the highest mean pH (4.0), followed by hand-squeezed peat rewetted with distilled H2O (3.8), then fresh peat (3.6). In comparison with fresh peat, air and oven drying lowered the mean pH value by 0.1 and 0.2 units, rewetting with N/100 CaCl2∙2H2O, by 0.4; N/10 KCl, by 0.5; and N/10 CaCl2∙2H2O, by 0.6 units approximately. The coefficients of variation and the confidence limits showed, for practical application, that all methods were equally reliable and that pH determined at any time of the year validly characterized a site.