PEATLANDS OF CANADA DATABASE

1. INTRODUCTION

Canada has the largest area of peatlands in the world, encompassing 12% of the land area or 1.1x10 km². These peatlands are essential to the global environment because they retain, purify and deliver fresh water, store carbon, absorb pollutants and support numerous species of plants and wildlife, many of them identified as endangered.

Open File 4002 consists of 3 elements:

i) a digital peatland database, distributed in ARC/EXPORT format (e00) and ESRI Shape format (shp), found under the directory/folder "data".

-base data (hydro) also included

ii) an ESRI plot file (gra) and a Postscript plot file (ps) of the Peatlands of Canada Map, called, found under the directory/folder "printfiles"

iii) a readme file in HTML and ASCII formats at the root directory/folder level

2. DEFINITIONS

Peat is material consisting largely of organic residues originating under more or less water‑saturated conditions through the incomplete decomposition of plant and animal constituents. It forms as a result of anaerobic conditions, low temperatures, and other complex causes.

Peatlands (formerly referred to as organic terrain or muskeg) are wetlands with massive deposits of peat that are at least 40 cm thick (National Wetlands Working Group, 1988). Each of the four classes of peatland ‑ bog, fen, swamp or marsh ‑ may take several to numerous

forms depending on the climate, hydrology, presence or absence of permafrost, form and composition of underlying surficial materials.

Bogs are peatlands having the water table at or near the surface (National Wetlands Working Group, 1988). Since the bog surface, which may be either raised or level with the surrounding terrain, is virtually unaffected by nutrient rich groundwater from the surrounding mineral

soils, it is generally acid and low in nutrients. The dominant materials are weakly to moderately decomposed sphagnum and woody peat, underlain at times by sedge peat. Bogs, which may be treed or treeless, are usually covered with Sphagnum spp. and ericaceous shrubs.

Fens are peatlands usually having the water table at or just above the surface (National Wet‑

lands Working Group, 1988). The waters are nutrient‑rich and originate from mineral soils.

The dominant materials are moderately to well‑decomposed sedge and/or brown moss peat of

variable thickness. The vegetation consists predominately of sedges, grasses, reeds, brown mosses, with some shrubs, and, at times, a sparse tree layer.

Marshs are mineral lands or peatlands periodically inundated by standing or slowly moving water (National Wetlands Working Group, 1988). Surface water levels may fluctuate

seasonally, with declining levels exposing drawdown zones of matted vegetation or mudflats. The nutrient‑rich waters vary from fresh to highly saline. The substratum usually consists of

mineral material, although occasionally it consists of well‑decomposed peat. Marshes characterisically show zonal or mosaic surface patterns composed of pools or channels interspersed with clumps of emergent sedges, grasses, rushes and reeds that border grassy meadows and peripheral bands of shrubs or trees. Submerged and floating aquatics flourish in areas of open water.

Swamps are mineral wetlands or peatlands with standing water or water gently flowing through pools or channels (National Wetlands Working Group, 1988). The water table is usually at or near the surface. Pronounced internal water movement from the margin or other

mineral sources results in nutrient rich waters. Peat, when present, is primarily well decomposed wood underlain, at times, by sedge peat. Vegetation is characterized by a

dense cover of deciduous or coniferous trees or shrubs, herbs and mosses.

3. PEATLAND DEVELOPMENT

The distribution of peatlands is determined by the climate and by the morphology of the land surface (National Wetlands Working Group, 1988). Climate determines the amount of water received and retained while the morphology of the land influences the distribution of the

water and, thus, the location of peatlands. Peatlands develop initially when areas of high water table are infilled with peat‑forming vegetation such as that found in fens and bogs. Bogs are dependant upon rainfall for water (ombrotrophic), while fens can also obtain water that originates from the surrounding (adjacent) mineral terrain (minerotrophic).

4. METHODOLOGY

The Peatlands of Canada, Open File 4002 is the database associated with an updated version of the Peatlands of Canada map, released as Geological Survey of Canada, Open File 3834 (Tarnocai et al., 2000). The first version of the Peatland of Canada map was released as Geological Survey of Canada, Open File 3152 (Tarnocai et al., 1995). The databases associated with both of these maps were derived primarily from the Soil Landscapes of Canada (SLC) database (Centre for Land and Biological Research, 1996), which contains information about the percentage of land area covered by the four peatland classes. The current peatland distribution map was generated using an updated peatland database that has a similar structure to the original database. The SLC database was the primary source of information for the Atlantic Provinces, Quebec, Ontario, British Columbia, the Yukon and parts of the Northwest Territories and Nunavut. Information for the Prairie Provinces was obtained primarily from Vitt et al. (1995), Halsey and Vitt (1997), Halsey et al. (1997) and Vitt et al. (in press). It should be noted that, for purposes of consistency with other sources of data, some units categorized in the Prairie Provinces as non‑patterned wooded fen have been designated bogs in this compilation. The Mackenzie River valley area in the western Northwest Territories was mapped on the basis of peatland information obtained from Geological Survey of Canada surficial geology maps (Geological Survey of Canada, B‑series and Open File Maps. 1973‑ 1980). Because peatland data for the Prairie Provinces and Mackenzie River valley were generated at a larger scale than that of the SLC landscape polygons, these data sets were resampled to a comparable scale using the SLC polygon structure. Peatland areas in the southern Arctic islands, Great Slave Lake area and eastern Nunavut were delineated on the basis of new air photo interpretations and archived field data.

5. DIGITAL DATABASE FORMAT

Projection:

Lambert Conic Conformal

Units metres

Datum NAD27

Standard parallels: 49 0 0 degrees N

77 0 0 degrees N

Central meridian: 95 0 0 degrees W

Latititude of origin: 49 0 0 degrees N

No x or y shift

The Peatland spatial cover is a simple cover of peatland types and their distribution related to each polygon. Associated with each polygon are the following items.

ITEM NAME

DESCRIPTION

TYPE

WIDTH (Dec)

PEAT-ID

Polygon ID

Binary

5 (0)

BOG_PCT

Percentage of Bog in Polygon

Integer

FEN_PCT

Percentage of Fen in Polygon

Integer

SWAMP_PCT

Percentage of Swamp in Polygon

Integer

MARSH_PCT

Percentage of Marsh in Polygon

Integer

TYPE

Dominant Peatland Type

Values: B = Bog

F = Fen

M = Marsh

S = Swamp

X = Bog and Fen

W = Water body

Q = no value (used for editing)

Integer

TOTAL

Percentage of Peatland in Polygon

Integer

6. CREDITS AND CITATIONS

RECOMMENDED CITATION:

For map:

Tarnocai, C., I.M. Kettles and B. Lacelle. 2000. Peatlands of Canada. Geological Survey of Canada, Open File 3834 (1:6 500 000 map).

For digital data:

Tarnocai, C., I.M. Kettles and B. Lacelle. 2002. Peatlands of Canada Database. Geological Survey of Canada, Open File 4002 .

ACKNOWLEDGEMENTS:

The authors acknowledge Mike Ballard, Polestar Geomatics, for cartographic and GIS work on the first Peatlands of Canada map and Linda Halsey, University of Alberta, for providing digital data files for the Prairie provinces. We would like to thank Hugo Velduis and S.D. Robinson for their constructive comments.

REFERENCES:

Ecoregions Working Group. 1989. Ecoclimatic Regions of Canada, First Approximation. Canada Committee on Ecological Land Classification, Environment Canada, Ecological Land Classification Series, No. 23, 119 p.

Fulton, R.J (Comp.). 1995. Surficial Materials of Canada. Geological Survey of Canada. Map 1880A.

Geological Survey of Canada, B‑series and Open File Maps. 1973‑1980. NTS numbers 85D,E; 95A,B,G,I,J,K,N,O; 96C,D,E; 106E,F,G,H,I,J,K,L,M,N,O; 107B; 116H,I,O,P; 117A,B,C,D. Geological Survey of Canada, Ottawa. 1:125 000 scale maps.

Halsey, L.A. and D.H. Vitt. 1997. Peatland inventory data for Saskatchewan (unpublished data).

Halsey, L.A., D.H. Vitt, H. Stephens and S. Zoltai. 1997. Wetlands of Manitoba. 1:1,000,000 scale map.

Kettles, I.M. and C. Tarnocai. In press. Development of a model for estimating the sensitivity of Canadian peatlands to climate warming. Geographie Physique and Quaternaire.

Centre for Land and Biological Research. 1996. Soil Landscapes of Canada, v.2.2. Agriculture and Agri-Food Canada, Ottawa.

National Wetlands Working Group. 1988. Wetlands of Canada. Canada Committee on Ecological Land Classification, Environment Canada, Ecological Land Classification Series, No. 24, 454 p.

Soil Carbon Data Base Working Group. 1993. Soil Carbon Data for Canadian Soils. Centre for Land and Biological Resources Research, Research Branch, Agriculture Canada, Ottawa, 137 p.

Tarnocai, C. 1989. Peat resources in Canada. in: R.J. Fulton (ed.), Quaternary Geology of Canada and Greenland, Geological Survey of Canada, Geology of Canada, No. 1 Chapter 11, p.676‑684.

Tarnocai, C., I.M. Kettles and M. Ballard. 1995. Peatlands of Canada. Geological Survey of Canada, Open File 3152. (map)

Tarnocai, C. 1998. The amount of organic carbon in various soil orders and ecological provinces in Canada in R. Lal, J.M. Kimble, R.F. Follett and B.A. Stewart (eds.), Soil processes and the Carbon Cycle. CRC Press, Boca Raton. p.81‑92

Vitt, D.H., L.A. Halsey, M.N. Thormann and T. Martin. 1995. Peatland inventory of Alberta. Prepared for the Alberta Task Force and Alberta Environmental Protection Agency.

Vitt, D.H., L.A. Halsey, I.E. Bauer, and C. Campbell. In press. Spatial and temporal

trends in carbon storage of peatlands of continental western Canada through the Holocene.

Canadian Journal of Earth Sciences.