Canada’s Ecozones
What are Ecozones?
Ecozones are areas of the earth's surface representing large and very generalized ecological
units characterized by abiotic and biotic factors.
Canadian national parks and reserves represent, to some degree, 14 of 15 Canadian
Ecozones, they are among Canada's most important and valued ecological assets.
Ecological land classification is a process of classifying ecologically distinctive areas of the
earth's surface. Each area can be viewed as a discrete system which has resulted from
interplay of geologic, landform, soil, vegetation, climatic, wildlife, water and human factors
which may be present.
Defining Ecozones and Ecosystems
The Canadian system of ecosystem classification divides the country into twenty major units –
fifteen are Terrestrial Ecozones and five are Marine Ecozones (see map below).
An ecosystem, in its simplest form, can be defined as home. Home, unlike the word house
conveys the idea that the occupants (people in the case of ourselves/ other living creatures in
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the case of the wilderness) are integral parts of the setting. As defined by Stan Rowe (1990) in
his Home Place book, we and all other organisms are part of ecosystems and not apart from
them. The concept of home therefore includes those who dwell there and everything that they
may need or rely on to live.
The State of the Environment Report (CCEA, Ed Wiken 1986) states in more scientific terms,
that an ecosystem is defined as a unit of nature comprised of organisms (including people), the
physical environment (land, water, climate) and the relationships that exist between them.
Large order ecosystems in a landscape sense are called ecozones in the Canadian system of
classification. These units depict areas of the earth’s surface where a fairly definitive and
enduring mix of abiotic and biotic elements exist. They are all distinctive places with distinctive
sets of characteristics. The structure, functions and processes associated with the biological
and physical characteristics in each place is relatively unique and enduring. Each
ecosystem/place is further characterized by relationships (dependencies, interactions,
transactions, intra-actions) which exist between the inherent biological and physical parts or
members --- these relationships are the cement which makes it possible for the system to hold
together on a more or less permanent basis.
The various order of ecosystems are related in a hierarchy in which a lower order ecosystem is
nested within a higher order one. This hierarchy allows us to view Canada’s ecosystems from
a broad perspective – the ecozones – or at a more detailed sub-unit level or at any level in
between. The ecozones are sub-divided into ecoprovinces, which are further divided into
ecoregions. These ecoregions, in turn, are sectioned into ecodistricts which are broken up into
even smaller units of ecosections, ecosites and finally ecoelements.
The fifteen (15) terrestrial ecozones of Canada are subdivided into 53 ecoprovinces, 217
ecoregions and 1021 ecodistricts. The Canadian marine ecosystem has not been completely
defined at the lower order to date. There are 5 marine ecozones, some of which are subdivided
into smaller sections while others are still only considered as a whole ecozone or ecoprovince.
Ecozones
Ecozones are areas of the earth's surface representative of large and very generalized units
characterized by interactive and adjusting abiotic and biotic factors. Canada was first
subdivided into 15 ecozones to meet reporting requirements of the first State of the
Environment Report for Canada published in 1986 (Wiken 1986 ). The ecozone lies at the top
of the ecological hierarchy as defined by the CCELC (Wiken 1979 ). In this context, the
ecozone defines on a subcontinental scale, the broad mosaics formed by the interaction of
macroscale climate, human activity, vegetation, soils, geological, and physiographic features of
the country. The former Terrestrial Ecozones of Canada report is being updated and will also
include descriptions for the recently developed marine ecozones
Ecoregions
Ecoregions are subdivisions of the ecozone characterized by distinctive large order landforms
or assemblages of regional landforms, small order macro- or mesoclimates, vegetation, soils,
water, and regional human activity patterns/uses. In this compilation, ecoregion boundaries
which already existed from previous work were refined to reflect more recent detailed
provincial studies and knowledge. The ecoregions constitute the major bridge between the
subcontinental scale ecozones and the more localized ecodistricts. The revisions to the
ecoregions provided the principal basis for the refinement of the original ecozones delineated
by Wiken (1986 ).
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Ecodistricts
Ecodistricts are subdivisions of ecoregions and are characterized by distinctive assemblages
of landform, relief, surficial geologic material, soil, water bodies, vegetation, and land uses. The
ecodistricts bring together various subregional units which had been defined by Environment
Canada, Agriculture and Agri-Food Canada and provincial agencies. Under the sponsorship of
the Northern Land Use Information Series (NLUIS) much of the Canadian Territories were
mapped and classified according to ecodistricts by Environment Canada. These descriptions
are contained on the individually published 1:250 000 NLUIS maps. These maps contain
information on soils, landforms, vegetation, wildlife, and water resources in the context of
ecodistricts. Another example, is the Centre for Land and Biological Resources Research's
development of a subregional unit termed an "agroecological resource area" for land
evaluation and modelling purposes. The agroecological resource areas were completed for the
agricultural portions of the Prairie Provinces (Dumanski et al. 1993 ; Pettapiece 1989 ; Eilers
and Mills 1990 ) and in Nova Scotia (Patterson and Langman 1992 ). The method of identifying
significant separations at this level was, in large part, based on differences in parent material,
topography, landform and soil development derived from the Soil Landscapes of Canada. The
Soil Landscapes maps represented the most detailed level (1:1 000 000 scale) of national
biophysical landscape information available for all of Canada during the compilation of the
ecodistrict boundaries.
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15 Terrestrial Ecozones of Canada
The Arctic Cordillera contains the only major mountainous
environment other than the Rocky Mountain system. It
occupies eastern Baffin and Devon islands and most of
Ellesmere and Bylot islands. The highest parts of these
volcanic rock ranges are strikingly crowned by ice caps and
multiple glaciers. The coast is marked with deep U-shaped
valleys formed by the Pleisocene glaciers and steep-sided
fjords reaching 1000 meters above the sea. Ice barrens and
frost-shattered rock stretch across most of the landscape
which is largely devoid of plants and animals. Most life forms
are found in the sheltered valleys at the lower elevations. The climate is extremely dry and cold.
The Northern Arctic Ecozone extends over most the nonmountainous areas of the Arctic Island and the portions of
northeastern Keewatin District and northern Quebec. It covers
1.5 million square kilometres or about one seventh of Canada.
Physically, the western portion consists mostly of lowland
plains covered with glacial moraine. East of a longitudinal line
which runs between Prince of Wales and Somerset Islands,
the terrain trends to be uplands consisting of plateaus and
rocky hills. Wide flat plains constitute many of the coastlines
and are often “fenced” by boulders carried ashore by strong tides and storm waves. Permafrost
lies beneath the entire ecozone and can extend down several hundred meters. Plants, other than
moss and lichen which thrive, are usually sparse and stunted due to the extreme forces of dry
climate, poor soil, permafrost and gale-force winds. There are no amphibians or reptiles in this
ecozone and only a few mammals, which can survive these conditions, most of which are
migratory such as muskox and caribou. These are rich grounds for migrant breeding shorebirds
and waterfowl.
The Southern Arctic is split by Hudson Bay into east and
west land portions. The Bay is included within this unit as a
marine environment. The larger land portion covers the
mainland of the Northwest Territories and Nunavut and the
smaller eastern segment bridges northern Quebec and
Labrador. Underlying much of this Southern Arctic ecozone is
the granite rock of the Canadian Shield. Known as the
Barrenlands, its terrain consists largely of strongly rolling
lowland plains, much of it is mantled by glacial moraines. It is
covered with shrublands, wet sedge meadows, rolling hills and plains and cold, clear lakes. Its
landscape is dotted with hummocks, mud boils, eskers and drumlins. It accommodates the
world’s largest concentration of free-roaming large mammals (caribou, muskox and moose). The
tree line extends only to the southern portion of this ecozone.
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The Taiga Plains are mainly located in the southwesterly
corner of the Northwest Territories; however, they also extend
into northeastern British Colombia and the upper margin of
Alberta. Upland and foothills areas and southerly locales tend
to be better drained, warmer and support mixed wood forest
characterized by white and black spruce, tamarack, white
birch, trembling aspen, balsam polar and lodgepole pine. It is
bordered by two of Canada’s largest fresh water lakes, Great
Slave Lake and Great Bear Lake. It encompasses the PeaceAthabaska Delta, a wetland habitat of global significance. As well, it is home of the world’s
largest Wood Bison herd and only known nesting site of the Whooping Crane. As the name
depicts, the landform consists of level to gently rolling plains, broad lowlands and plateaus.
There are also large river valleys, oxbow lakes, large wetlands and muskeg. For six to eight
months of the year the ground is mostly frozen and snow and ice covered. Much of the area is
covered with transition forest and wildlife is more abundant (wolf, fox, hare, lynx, porcupine,
beaver, squirrel, etc.) A few year-round bird species are present (raven, grouse, grey jay, redpoll
and ptarmigan) as well as insect-eating forest birds that feed on the high insect population.
The Taiga Shield lies on either side of Hudson Bay. The
eastern segment occupies the central part of Quebec and
Labrador, and a western segment occupies portions of
northern Manitoba, Saskatchewan and the south-central area
of the continental Northwest Territories. Along the northern
edge of this ecozone, the poleward limits of tree growth are
reached. The world’s oldest rocks, almost 4 billion years old,
can be found north of Great Slave Lake. This ecozone
includes bald Precambrian bedrock which is dotted with
millions of lakes and wetlands that were formed by glacial erosion. The Taiga Shield is an
“ecological crossroads” at which the Arctic and Boreal families of characteristics meet and
provides a wide variety of habitats for birds and mammals. The return of water fowl at spring
migration provides a spectacular wildlife display yearly.
The Taiga Cordillera is located along the northern extent of
the Rocky Mountain system. It covers segments of the Yukon
Territory and the southwestern portion of the Northwest
Territories. Steep, mountainous topography, consisting of
repetitive, sharply etched ridges and narrow valleys,
predominates. It contains some of Canada’s largest
waterfalls, deepest canyons and wildest rivers. The original
sedimentary rocks underwent significant folding and uplifting
over 200 million years ago due to tectonic plate drifting. At its
most active period about 100 million years ago, red-hot molten rock was formed as a result of
local stresses and forced to the surface to produce igneous rock. Since that time, extensive
erosion was exerted on the rocks by glacial movement, streams and rivers. The climate is
generally dry and cold. Vegetation growth is dependent on their position on the mountain slope.
Western slopes usually have the most luxuriant growth due to prevailing weather patterns that
deposit more rain on the western side as they progress eastward. As well, southern slopes
experience greater hours of sunshine to encourage growth. High winds and harsh conditions
produce stunted growth on higher slopes while protected soil rich valleys are more productive.
This diverse habitat also encourages a larger number of wildlife species from both arctic and
temperate climates to reside in this ecozone.
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The Hudson Plains is an area centered in northern Ontario
that extends into northeastern Manitoba and western Quebec.
Although wetlands are distributed throughout the nation, the
largest extensive area is associated with this ecozone. Canada
has approximately 25% of the world’s wetlands, almost all of
which are found in the Hudson Plain ecozone, perhaps the
largest coextensive wetland on the planet. The landscape is
marked by a series of arcing and evenly-spaced white lines
that are raised beaches, caused by rebounding from glacial
retreat, interspersed with bogs and swamps. The early immigrants to this region referred to it as
the “insect-infested land of bog and fog” in the warm season. Although adversary to human
habitation, this characteristic has made the Hudson Plains ecozone an ideal breeding ground for
migratory birds. This ecozone is rich in rivers which generally have their headwaters in the
Boreal Shield ecozone (to the south) and flow northward toward Hudson Bay. Spring floods can
push water levels 10 to 15 meters higher than usual. On average, the mean maximum snow
cover is less than 1 meter in depth. Extending south from the Hudson Bay coast (which is
treeless) is a band of tundra approximately 30 kilometres wide. Moving further south, a taiga area
of transition forest extends in a narrow band around the tundra area. It contains similar tree
species to the boreal forests but in a more sparse and stunted form.
The Boreal Plains extend as a wide band from the Peace
River country of British Columbia in the northwest to the
southeastern corner of Manitoba. The physical features of this
unit are similar to those of the Prairie Ecozone to the south,
low-lying valleys and plains. Timber covers 84% of the Boreal
Plain and forestry is the primary industry. Rich vegetation
abounds around sloughs and marshes and poorly-drained
areas have produced extensive bogs. Human activity has
been blamed for the extinction of several species of mammal
and bird in this ecozone as well as the threat to several others.
The Boreal Shield, Canada’s largest ecozone, is a broadly
"U" shaped zone that extends from northern Saskatchewan
east to Newfoundland, passing north of Lake Winnipeg, the
Great Lakes and the St. Lawrence River. It is the overlap of
the Canadian Shield and the boreal forest. The Boreal Shield
includes parts of six provinces and covers almost 20% of
Canada’s land mass and 10% of its fresh water. Metamorphic
gneiss, a highly banded rock formed by intense pressure and
heat provides the foundation of much of this ecozone. The
advance and retreat of glaciers gouged the rocks and deposited gravel, sand and other glacial
debris forming poorly drained depressions that have become the lakes, ponds and wetlands of
the Boreal Shield. Nearly 20% of the ecozone is covered with wetlands. Many of those to the
south have been harnessed as commercial berry farms for cranberries and blueberries. Wildlife
is abundant. Climatic conditions vary slightly over the area. This ecozone is largely influenced by
cold Hudson Bay air masses, which are also responsible for relatively high levels of
precipitation.
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The Boreal Cordillera is located in the mid section of
Canadian Rocky Mountain system. It covers sections of
northern British Columbia and the southern Yukon Territory.
The area is generally characterized by the mountain ranges
which contain numerous high peaks and extensive plateaus,
and the intermontane plains. Ice age glaciers covered virtually
all plateau areas and left widespread deposits of glacial debris.
These mountain systems are lower and more subdued than
the coastal ranges and southeastern ranges. Moist Pacific air
frequently causes sudden, violent storms during the summer
and warm chinook winds in winter. The St.Elias Mountains which have perpetual ice and snow
cover are found in this ecozone. The vegetation for this section is typical of the Boreal Forest.
Although many species inhabit this ecozone, most leave by mid-winter to avoid the deep snow.
There are no reptiles in this ecozone and the only amphibians are the Western Toad, Wood Frog
and Spotted Frog.
The Pacific Maritime, as the name implies, includes the
land margin along the entire Pacific Coast, as well as the
marine portion. Mountainous topography dominates, cut
through by numerous fjords and glacial valleys and bordered
by coastal plains along the ocean margin and B.C.’s marine
islands. It contains the tallest trees (Sitka Spruce, 95 meters
high), has the most rainfall (3000mm.) and the longest (up to
190 km.) and highest fjords (sheer sides 2000 meters).
B.C.’s tallest mountain at 4000 meters, Mount Waddington,
is found in the Pacific Maritime ecozone as well as
Findlayson Channel, the deepest fjord in the world at 795 meters. The famous rain forests of
this region are composed of the coastal Western Hemlock. Less than 0.2% of the earth’s land
surface is covered by coastal temperate rainforest. The largest undeveloped tracts of these
forests are found in South America and North America (approximately 106,000 square
kilometers in this ecozone). These forests contain ecosystems with the highest biomass per
hectare on Earth. This ecozone also contains one of B.C.’s rarest forests and one of North
America’s most endangered, the Arbutus and Garry Oak woodland, which grows in the dry rain
shadow climate of the Gulf Islands and Saanich Peninsula. The Pacific Maritime ecozone lies
within the Pacific Ring of Fire, a narrow, semi-circular area known for volcanic eruptions and
earthquakes caused by friction between the earth's crustal plates. Numerous hotsprings
abound. Several species and subspecies are native to only a few islands of the ecozone and
are rare, endangered or extinct.
The Montane Cordillera, contains most of southern British
Colombia and a portion of southwestern Alberta. It is
essentially a rugged mountains unit which surrounds several
major interior plains. The plains are more extensive to the
north and finger out as intermontane valleys towards the
southerly half. This ecozone is the most climatically diverse
containing some of the driest, wettest, coldest and hottest
conditions within Canada. The ecosystems range from
alpine tundra and dense coniferous forests to dry sagebrush
and grasslands. The Montane Cordillera encompasses two
of the four significant agricultural areas of B.C., the Creston Valley and the Okanagan Valley.
This ecozone is also known for forestry and coal mining. The pronounced rainshadow cast by
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the massive Coastal Mountains makes the valley bottoms of the south-central interior the driest
climates of B.C. The air releases moisture again, creating an interior rain belt as it ascends the
mountain ranges defining the eastern extent of this ecozone. Natural grasslands in this
ecozone have been mainly replaced by introduced species as well as destroyed by cattle
grazing, settlement, orchard and crop planting. Wildlife is diverse but is being pressured by
development.
The Prairies, named the "bread basket" of Canada,
occupies a semi-circular area that has its base on the
Canada-U.S. border and arcs from the western edge of
Alberta to the eastern edge of Manitoba. It is the northern
extension of the Great Plains of America. More than 90% of
the ecozone is covered by treeless grassland in the form of
agricultural cropland, rangeland and pasture. Large numbers
of threatened and endangered species are found on the
Prairie ecozone and it has become Canada’s most
endangered natural habitat. Many of the lakes in this ecozone are the remnants of the former
glacial Lake Agassiz. As well, there are rich reservoirs of oil and gas trapped below the
surface. The ecozone is reputed for its severe weather storms and a portion of south-central
Alberta is known for the worst hailstorms in North America. It is also one of the windiest places
in Canada which can cause severe soil erosion. Hydro and thermal power generation has
impacted upon virtually every major natural water system in the ecozone.
The Atlantic Maritime extends from the mouth of the St.
Lawrence River southeasterly across New Brunswick, and
into Nova Scotia and Prince Edward Island. The ecozone is
dominated by the interior Appalachian upland and the
Northumberland coastal plain. Some of the unique natural
ecosystems found in this area are sand dunes along the
seaboard, coastal islands and mixedwood Acadian forests.
The Atlantic Maritime ecozone is located at the northerly end
of the chain of Appalachian mountains that run from
Newfoundland to the southern state of Alabama. Soil cover is shallow over most of the
ecozone and the population tends to gravitate toward the portion of the ecozone with the
deeper, more fertile soil of the coastal lowlands of the Northumberland Plain. This ecozone has
over 11,000 kilometers of coastline that is predominantly a mix of sand dunes and tidal flats.
The Atlantic Maritime ecozone has over 4000 offshore islands and includes the Bay of Fundy
which is known for its spectacular tides. The endangered Blanding’s Turtle is found almost
exclusively in Nova Scotia’s Kejimkujik National Park which is within this ecozone.
The Mixedwood Plains, covering the Lower Great Lakes St.Lawrence Valley areas, is among the smallest. However,
its combination of agricultural soils, gentle topography and a
relatively warm summer climate have caused this ecozone to
be one of the most intensively used and highly populated.
This ecozone is the industrial and commercial heartland of
Canada due mainly to the multiple modes of transportation
available throughout this area. Over 10,000 years ago, the
Mixedwood Plains was covered by the Champlain Sea which
deposited much of the marine clay found in Southeastern Ontario and southwestern Quebec.
One of the most renowned physical features of this ecozone is the Niagara Escarpment which
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includes Niagara Falls, one of the largest tourist attractions in North America. This ecozone
also has several prominent moraines and drumlins as well as a dormant volcano. The
St.Lawrence River with a length of 600 kilometers is dominant in this ecozone. It has the
largest outflow of water of any river in Canada and is thirteenth in the world. It is fed by the
Great Lakes which hold nearly 20% of the world’s fresh water. Human intervention has
destroyed much of this ecozone’s natural vegetation leaving only small pockets of undisturbed
area. Special habitat areas such as the Carolinian Forest, which contain 40% of Ontario’s rare
plants are under considerable pressure from human actions.
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Northern Arctic
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Arctic Archipelago
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Southern Arctic
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Taiga Plains
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Taiga Shield
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Taiga Cordillera
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Hudson Plains
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Boreal Plains
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Boreal Shield
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Boreal Cordillera
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Pacific Maritime
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Montane Cordillera
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Prairies
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Atlantic Maritime
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Mixedwood Plains
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