Peatland Types Research Articles

Metal concentrations in chrionomids in relation to peatland geochemistry

Concentrations of Zn, Cu, Al, Fe, and Mn were determined in Chironomidae (Diptera) larvae sampled from three sites within eight peatlands, located in south-central Ontario, Canada. The eight peatlands displayed a range in pH and alkalinity and were classified abiotically (i.e., chemically, hydrologically) and biotically (i.e., dominant vegetation present) as mineral-poor, moderately poor, or as mineral-rich fen. Surface peats of mineral-poor fens were distinct from those of moderately poor and mineral-rich fens; mineral-poor fens contained higher concentrations of organic matter with low concentrations of easily reducible Mn vs. the moderately poor and mineral rich fens. A one-way nested ANOVA indicated that chironomid metal concentrations were peatland dependent (P<0.05). To determine if differences in chironomid metal concentrations among the peatlands could be related to peat geochemistry, an R2 MAX procedure using peat geochemistry as the independent variable and chironomid metal concentrations as the dependent variable was applied. Peat geochemistry was defined as concentrations of peat organic matter, reducible Fe (Fe oxides), reducible Mn (Mn oxides) and easily reducible metal (where metal = Zn, Cu, Al, Mn and Fe), and reducible metal and organically bound metal. Chironomids from mineralrich peatlands, i.e., peatlands low in organic matter with high concentrations of reducible Mn and Fe or easily extractable metal contained greater concentrations of Zn, Mn, and Fe vs. chironomids sampled from mineral poor peatlands, i.e., peatlands with high concentrations of peat organic matter and low concentrations of reducible Mn or easily extractable metal. In contrast, Cu concentrations were greatest in larvae sampled from mineral-poor vs. mineral-rich peatlands. Aluminum larvae concentrations were independent of peat geochemistry. We suggest that bioavailability of metals such as Zn, Fe, and Mn will be greater to invertebrates inhabiting mineral rich vs. mineral poor fens, whereas greater chironomid Cu concentrations will be found in chironomids sampled from mineral poor fens. Differences in metal availability to invertebrates among peatland types has important implications when comparing the impact of contaminant transfer to higher trophic levels among different types of peatlands.

Regional variation of dissolved organic matter in running waters in central northern Sweden

Regional variations in the concentrations of DOM were studied in running waters in central-northern Sweden. The highest concentrations occurred in the coastal areas, and there was a marked trend with decreasing concentrations towards the inland and the mountain range further west. Explanation of these differences are regional differences in forestland productivity, the occurrence and type of peatlands, annual runoff patterns and soil drainage conditions. Anthropogenic factors, such as atmospheric deposition of acids and forestry, have probably not contributed to the regional differences.

AN OVERVIEW OF FACTORS THAT INFLUENCE THE DEVELOPMENT OF CANADIAN PEATLANDS

AbstractCanadian peatlands can be classified into ombrotrophic bogs and minerotrophic fens, the latter subdivided into poor, moderate-rich, and extreme-rich fens, each with distinctive indicator species, acidity, alkalinity, and base cation content. If hydrology is considered the most important factor in peatland classification then the primary division must be between ombrotrophic bogs and minerotrophic fens; however both chemical and vegetational differences strongly indicate that the primary division of peatlands should be between acidic, Sphagnum-dominated bogs and poor fens on the one hand, and alkaline, brown-moss-dominated rich fens on the other. Although some metals such as sulphur and aluminum also vary along this gradient, nutrient contents of the surface waters do not. Bogs and fens are oligotrophic to mesotrophic wetlands that should be distinguished from eutrophic, non-peat-forming wetlands such as marshes and swamps by the presence in the former of a well-developed ground layer of bryophytes associated with relatively little seasonal water level fluctuation. Oligotrophy is probably maintained in bogs and poor fens by reduced water flow, whereas rich fens maintain mesotrophy by having larger water through-puts; however this is not well documented. Sphagnum appears to have real ecological significance, both in the initial stages of acidification and in controlling surface water temperature. Seasonal variation in surface water chemistry in all peatland types is relatively small, however precipitation events leading to changes in water levels do affect some chemical components. Although both autogenic and allogenic factors affect peatland development, initiation of peat formation and early development of peatlands during the Early and Mid Holocene were considerably influenced by regional climatic change. Later developmental patterns during the late Holocene and those seen at the present time appear to be more influenced by autogenic factors.

Hydrogeologic controls on peatland development in the Malloryville Wetland, New York (USA)

The Malloryville Wetland Complex, a small kettle-hole peatland, contains a diversity of peatland types. The wetland has a ‘rich’ side that contains wetland vegetation associated with solute-rich, near-neutral pH (minerotrophic) water, and a ‘poor’ side containing vegetation that grows in solute-poor and acidic (ombrotrophic) water. Vertical head gradients at piezometer clusters located in the rich side clearly show that groundwater is moving upwards towards the land surface, consistent with the vegetation types and surface water quality. In contrast, vertical head gradients also show that groundwater is moving upward in the poor side even though the vegetation and surface water chemistry are not minerotrophic. An incipient raised bog in the center of the poor side is the only site where groundwater moves consistently downward. A peat core collected at the bog center shows that the bog site was initially covered by minerotrophic vegetation, typically found in groundwater discharge zones, which was later replaced by ombrotrophic bog vegetation. Theoretical computer simulation experiments of the bog hydrogeologic setting through time suggest that the direction of vertical groundwater flow at the bog site permanently changed from up to down when a water table mound developed under a convex-shaped fen peat mound that probably formed because of differential peat accumulation. Ombrotrophic conditions and bog vegetation probably began when the fen water table mound grew sufficiently large enough to divert the upward movement of regional groundwater. The transition from rich to poor environments probably occurred when the wetland water table was substantially below the elevation of the surrounding regional water table.

Potential Carbon Losses From Peat Profiles: Effects of Temperature, Drought Cycles, and Fire.

Global warming and the resultant increase in evapotranspiration might lead to lowered water tables in peatlands and an increase in fire frequency. The objective of this study was to investigate some of the potential effects of these changes on peat decomposition. Dry mass losses and emissions of CO2 and CH4 from peat samples taken from three depth layers (0-10, 10-20, and 30-40 cm) of a black spruce peatland were measured in the laboratory at 8°, 16°, and 24°C under two moisture treatments. Effects of deep peat fire on decomposition were also simulated by burning the upper layer (0-10 cm) of peat and adding the ash to peat samples from the 10-20 cm layer. CH4 release averaged <1% of total carbon loss in flooded samples. Release of CO2 was 4-9 times greater from the 0-10 cm layer than from the 30-40 cm layer. After 120 d, the 30-40 cm layer had lost <1% of its original dry mass in all treatments. Higher temperatures strongly promoted decomposition of samples exposed to drying cycles but had little effect on decomposition of continuously flooded samples. Ash addition had variable effects on CO2 emissions but may have promoted CH4 production. It is suggested that in certain situations, global warming may not cause appreciable increases in carbon loss from peat deposits. The results indicate that some deeper peats are resistant to decay even when exposed to warm, aerobic conditions. However, further experimental work is needed to predict the long-term response of peat deposits to changes in water levels in different peatland types.

Growth, Production, and Decomposition Dynamics of Sphagnum under Natural and Experimentally Acidified Conditions

Annual linear growth, net primary production, and decomposition of Sphagnum fuscum, Sphagnum magellanicum, and Sphagnum angustifolium were measured under experimental acidification and natural conditions in a poor fen at the Experimental Lakes Area (ELA), Ontario, Canada. Acidification increased growth and production of most species (2 out of 3 in the oligotrophic zone, and 2 out of 3 in the minerotrophic zone) in the first 2 yr. After 2—3 yr of artificial acidification, growth and production were not stimulated to the same extent in experimental areas as in earlier years. After 4 yr, growth and production in the experimental area declined so that they were the same as controls for 4 of the 6 treatments. Therefore, the effect of the acid treatment changed over the years. With 4 yr of simulated “acid rain,” decomposition was unaffected. Our results suggest that the fertilizing effect of SO42— and NO3— in North American acid precipitation as suggested previously in the literature is a very short—term one, at least for this type of peatland. Under natural conditions, in the oligotrophic central zone of mire 239, production for hollow species was somewhat greater than for hummock species for the 4 yr studied. Since the decomposition rate ratio between hummock—top, mid—hummock, and hollow species is roughly in the ratio 7:9:13, the rate of peat accumulation should be higher in hummocks. Hence hummocks appear to be maintained in this poor fen due to low decomposition rates rather than relatively high production. For 3 of the 4 yr studied (1985—1987) in the minerotrophic edge zone, hummock production (303, 175, and 156 g°m—2°yr—1, respectively) was greater than hollow (198, 100, and 97 g°M—2°yr—1) and mid—hummock production (103, 59, and 52 g°m—2°yr—1). The relative decomposition rates of the species had the same ratio as in the oligotrophic zone. Thus hummocks appear to be expanding in this minerotrophic edge zone at a faster rate than in the oligotrophic zone.

Sphagnum-dominated peatlands of the hyperoceanic British Columbia coast: patterns in surface water chemistry and vegetation

Vegetation from 133 relevés representing a broad spectrum of peatland types from the Prince Rupert area, British Columbia was divided into six relevé groups. The 210 taxa found in these relevés were classified into six species groups. In general, the species groups are related to one another along shade and height (above water level) gradients. Chemical and physiographic gradients that correlate with the relevé distribution pattern on a detrended correspondence analysis ordination are surface water chemistry, shade, and height. In particular, the major gradient influencing the first axis of the ordination is shade. The second axis of the ordination is related to a complex chemical gradient in which hydrogen ion, calcium, and sulphate are the most important components. These chemical changes are influenced by ombrotrophy. Surface water chemistry patterns show enriched ionic conditions on Graham Island (Queen Charlotte Islands), with a decrease inland. Especially important is the decrease of sodium and chloride ion. The peatlands studied include ombrotrophic bogs and soligenous fens. Raised bogs were found in basins, whereas blanket bogs occurred on gentle slopes at the most oceanic site. Pinuscontorta Loud. var. contorta is most abundant on ombrotrophic sites, whereas Chamaecyparisnootkatensis (Lamb.) Spach is dominant in soligenous fens. Soligenous poor fen, characterized by high Sphagnum abundance in lawns and forest islands and pH of 4.4–6.6, is the peatland type most frequently encountered in the study area.

Scotlands threatened mires and mosses: Policies to protect the peatlands of caithness and sutherland

Summary Scottish peatlands have suffered loss and damage for centuries through cutting for fuel and agricultural and forestry practices. The ombrogenous blanket mires of Caithness and Sutherland (the ‘Flow Country’) are of international importance for the range and quality of their peatland types and vegetation, and their breeding bird populations. Loss of this habitat in the last decade, due to rapid expansion of forestry, caused great concern which was expressed by voluntary and statutory nature conservation organizations and the national media. Government at both national and local levels responded with changes in forestry policies, protection of large areas of peatland and by a land-use strategy which divides the area into four forestry policy zones.

Peatland in Northern Ireland: inventory and prospect

Peatland has been classified and mapped at 1: 20.000 throughout Northern Ireland using air photographs. The distribution is tabulated for six survey blocks and presented in maps showing percent cover of total and intact peatland; only 12% of both major types of peatland has survived intact. In addition, samples from the original survey maps show different peatland landscapes. Lowland peatland. only 15% of the total, is equally spread between east and west: the largest bogs are small on an all Ireland basis. The much more extensive blanket peat is concentrated in the west: it is all hill peat, except for a small area in west Fermanagh. The survey is a framework for conservation: a benchmark to monitor future losses, notably by machine cutting in the 1980s, and could be further developed using Geographical Information Systems (GIS).

Relative Abundance of Herpetofauna among Eight Types of Maine Peatland Vegetation

Relative Abundance of Herpetofauna among Eight Types of Maine Peatland Vegetation

Review of the inorganic geochemistry of peats and peatland waters

The major floristic and geochemical differences between bogs, fens, and swamps are summarized, and the most common peat types described. This is followed by a critical, historical review of the literature. The methods used to measure the pH of peatland (mire) waters are examined, and the pH range of various peatland types is reported. In addition, horizontal and vertical pH variations are illustrated, and factors affecting the pH of these waters reviewed. The cause of the low pH of surface waters of Sphagnum bogs (approximately pH 4) is critically investigated, and the relative importance of dissolved CO 2 and other inorganic acids, and organic acids to the low pH is assessed. Cation exchange on the surfaces of Sphagnum mosses is found to be a relatively unimportant acidification mechanism, but important to the chemical ecology of the plants. The redox chemistry of mire waters is described in terms of the geochemistry of such redox indicators as O 2, CO 2, CH 4, CO, H 2, H 2S, SO 4 2−, native Cu, and siderite (FeCO 3). Published studies of Eh in peatlands are cited, and the problems of Eh measurement and interpretation are explored. The chemical composition of mire waters (major and trace metals, and nonmetallic species) is examined, and factors affecting their composition reported. The abundance and distribution of mineral matter in peats is described, and the occurrence and formation of minerals of Fe (pyrite and other sulphides, siderite, vivianite), Cu (chalcopyrite, native Cu, covellite) and Zn (smithsonite and wurtzite) investigated. The abundance and distribution of major elements (Si, Al, Na, K, Mg, Ca) and trace metals (Ni, V, Cr, Fe, Mn, Cu, U, Zn, Pb) is described, and factors affecting their solubility examined.

DISSOLVED IRON AND ORGANIC MATTER IN NORTHERN PEATLANDS

Concentrations of dissolved (passing through aerobic filtration) iron and organic carbon (DOC) were determined in water samples collected from subarctic fens near Schefferville and boreal bogs near Sept-Iles, northern Quebec. Total iron and DOC concentrations averaged 19.3 and 1.2 mg/L, respectively, for all the samples analyzed and were weakly negatively correlated. The bog waters were higher in DOC and lower in total iron than the fen waters. Subsurface samples from the fens, underlain by iron-rich materials, showed increased iron concentrations, whereas the bogs, underlain by iron-poor materials, did not. Differences in the DOC: iron ratios can be explained by the different pathways of water and sources of DOC and iron in the two types of peatland. Reaction of the peat water samples with o-phenanthroline suggests both organically complexed and fine colloidal and dissolved forms of iron. The continuous variation method showed that peak absorbance occurs at DOC: iron ratios of 6:1 to 8:1, suggesting that all but the subsurface fen samples contained organic matter complexes that were undersaturated with respect to iron.

La répartition et l'habitat du Tomenthypnum falcifolium au Québec–Labrador

The discovery of Tomenthypnum falcifolium (Ren. ex Nich.) Tuom. in Canada is rather recent. For a long time, it was considered as a variety of Tomenthypnum nitens. Some characters allowing the distinction of the two species are discussed and illustrated. Distribution maps of both species in the Québec–Labrador Peninsula are presented. Habitat conditions of Tomenthypnum falcifolium in the Laurentides Park are derived from a study of peatland vegetation. It grows mainly in extremely poor fens, the dominant peatland type of this region. It is a hummock-preferring species and never forms extensive colonies. Its ecological amplitude is then rather different from that of Tomenthypnum nitens which is more commonly found in rich fens.

Ecological and hydrological aspects of peat formation

Abstract Peat formation is dependent upon an imbalance in the energetic relations of an ecosystem such that the total energy fixation by photosynthesis exceeds the total respiration on the part of the plants, animal consumers, detritivores and microbial components of the ecosystem. The imbalance comes about through the impedence of some detritivore and microbial activity as a result of the waterlogging of the environment. A knowledge of hydrological relationships in different types of mire (any freshwater wetland ecosystem in which soil organic matter accumulates) is necessary for the understanding of the rate of formation and the nature of the peat formed. A hydrological scheme for mire classification is discussed in relation to the type of peat developed from the mire types described, particularly the proportion of inorganic material incorporated into various peatland types. Two major hydrological divisions can be distinguished—those depending entirely upon rainfall for their water intake and those receiving water both by rainfall and overland drainage. The differentiation is of profound importance in terms of the inorganic (loss on ignition; ash) content of the peat, since the rain-based (ombrotrophic) system generally has a far more limited supply of inorganic material than the flow-fed (rheotrophic) one. One must seek models for coal-forming systems among ombrogenous tropical mires. Elevated peat-forming surfaces equivalent to the temperate raised mires are recorded from tropical areas and some of these bear vegetation whose physiognomy (general form and structure) resembles that of reconstructed coal forests. In these bog forests, peats of low ash content accumulate and such mires may prove to be the closest modern analogy to coalforming systems.

Ecological Effects of Acid Deposition Upon Peatlands: A Neglected Field in "Acid-Rain" Research

Certain types of peatlands are probably highly susceptible to anthropogenic acidification, yet very little research is being done on the vulnerability of bogs and fens to acid deposition. We have documented the need for such research and for studies of the role of acidification — natural and anthropogenic — in determining nutrient availability, metal mobilization, and biogeochemical cycling by fauna and microflora. Possible effects of hydrological changes, and of drainage from acid peatlands to lakes and streams, are noted. We provide an outline of possible responses of plants and animals to acidification; these should be investigated at species, community, and ecosystem levels. Studies of peatlands as possible sources of the gaseous precursors of acid deposition are needed. Different approaches to examining the responses of peatlands to acid deposition include geographical surveys, experimental studies, short-term, long-term, and paleoecological investigations, and analysis of biogeochemical mass-balances. Finally, we emphasize the need for inclusive studies of peatlands in relation to surrounding uplands and to the streams and lakes that receive their drainage.

Notes. Trace element content of northern Ontario peat

Peat samples were collected at 0-20- and 20-40-cm depths from several peatland ecosystems located in northern Ontario, Canada. Analysis was made for the trace metals Zn, Pb, Cu, Cr, Cd, and Hg. Concentration values in general were in the low ppm range and did not significantly differ in terms of peatland type or depth except for Pb. This element was signficantly higher in surface peats in bogs and fens. Concentration of metals in peats found in the study were equivalent to those in US coals, suggesting caution during combustion in terms of potential atmospheric input of metals.

Peatlands of eastern Newfoundland: distribution, morphology, vegetation, and nutrient status

The peatlands of eastern Newfoundland are classified into six morphological types: domed bog, blanket bog, slope bog, basins bog, ribbed fen, and slope fen. The separation of types is based on peat depth, surface physiognomy and slope, underlying basin or slope morphology, botanical constituents, and degree of humification of the peat strata. Low elevation aerial oblique photographs and stratigraphical profiles of the six representative morphological peatland types are presented.The peatland vegetation is classified into eight associations and four pool communities; three alliances are also proposed and comparisons with syntaxonomical classifications of European peatlands are discussed. Phytosociological tables are presented for the dry bog vegetation, wet bog vegetation, and fen vegetation; a summary table showing differential species groups of each syntaxon is also presented. pH and total contents of nitrogen, calcium, and iron are determined for the major vegetation types.

Thawing of seasonally frozen ground in organic terrain in central Saskatchewan

Surveys of ground frost in three peatland types, sedge fen, transitional (tamarack) fen, and black spruce – Sphagnum bog, in central Saskatchewan showed differences in depth of freezing and rates of thawing. The maximum depth of freezing and most rapid removal of ground frost occurred in the fen and transitional fen. Seasonal frost was found in the bog until late August. Thawing occurs primarily from the surface downward. However, some thawing from below may occur in the fen. Thawing from the surface is strongly related to the number of thawing degree–days.

Ontario clay belt peatlands—are they suitable for forest drainage?

Peatland types were compared to reveal differences in growth of dominant and codominant trees from undrained and artificially drained sites. The comparisons, based on tree height attained at the age of 100 years, indicate that growth improves by about 6 m in bog types and by about 4 m in fen–marsh types. To allow identification of similar sites in different localities and prediction of growth potential of sites not directly under study, 15 peatland types were assigned to five trophic groups on the basis of macronutrient content of the peat, using an automatic clustering method. The nutrient elements considered are known to influence growth on peatlands. The paper gives an account of site conditions. sampling technique, methods of comparison, and clustering. Detailed results are presented and explained.

The Relationship Between Net Primary Production and Accumulation for a Peatland in Southeastern Manitoba

Two functional attributes of an ecosystem, net primary production and subsequent dry matter accumulation, were examined in four peatland types (lagg, bog, muskeg and bog forest) located in southeastern Manitoba. A preliminary peat accumulation budget was constructed by relating the amount of litter present after a single year of decomposition to the initial litter income and annual net primary production. Annual litter “income” in the four vegetation zones ranged from 489 gm/m2, which represented 69% to 90% of the calculated net primary production. Decomposition losses in the following year amounted to approximately one quarter of the original income. An average annual accumulation rate of 26 gm/m2/yr to 51 gm/m2/yr was calculated from radiocarbon—dated peat cores, thus suggesting that less than 10% of the annual net primary production will remain as peat.