Accounting for ecosystem change in Canada
2.0 Ecosystem extent and drivers of change

Canada is a vast country, the second largest in the world. Canada’s terrestrial and freshwater area extends across 9.98 million km² while its jurisdiction over the ocean includes 5.75 million km² within the limit of its exclusive economic zone (EEZ), and a total of 7.1 million km² including jurisdiction over the seabed and subsoil of the extended continental shelf of the Arctic and Atlantic oceans.^Note

Many different ecosystems occupy Canada’s land, freshwater and seascapes. Temperate and boreal forests, peatlands, tundra, alpine meadows, temperate grasslands, coastal wetlands and coral reefs can be delineated based on the interaction of biological communities of organisms and their environment. Characteristics such as climate, topography, soils, vegetation, wildlife and human activity interact and can be used to define the extent of terrestrial ecosystems at different scales. For marine and coastal ecosystems, climate, biota, currents, seafloor substrate, and horizontal and vertical zonation—the distance from the coast and depth in the water column—can be important components that help define ecosystem areas. Some of these characteristics are relatively fixed and change only slowly, but others can change rapidly, reflecting changes in land use and other pressures.

Human activity and land use change have greatly altered many of Canada’s natural ecosystems. Major changes in Canada’s landscapes occurred following European colonization including draining wetlands and clearing woodlands for agriculture and the establishment of settlements along waterways and rail lines, near harbours and on fertile lands. The loss of free-roaming plains bison to hunting and the opening of the Prairies to agriculture in the late 1800s altered the native grasslands and plains.^Note Natural forests have increasingly been converted to managed forests over the past century, with impacts on biodiversity and the loss of many old growth forests.^Note

Land use changes occur as a result of changes in patterns of human activity. Some examples include urban expansion into nearby agricultural, forest or wetland areas at the periphery of cities and the conversion of forests to agricultural land. Industrial activities such as forestry, mining and oil exploration can cause deforestation and ecosystem fragmentation in more remote areas of the country.^Note Human consumption and production activities also drive local and global ecosystem change.^Note For example, emissions released from human activities can affect the quality of air, water and land and influence the global climate system. Climate change is increasingly impacting ecosystem functions and the health and distribution of many plant and animal species across the country.^Note

This report brings together consistent statistics from many sources to map and describe the extent of Canada’s ecosystems and changes in ecosystem condition and services that will affect the health of the economy, society and human well-being.

2.1 Terrestrial and freshwater ecosystems

Canada has some of the largest forest, tundra, prairie, wetland and freshwater ecosystems in the world (Map 2.1). Overall, approximately 36% of the country is covered by forest, 25% by arctic tundra, 4% by grassland including natural pasture or rangeland, 2% by permanent snow and ice cover and 28% by other natural and semi-natural areas such as woodland, shrubland, alpine tundra, barrenland, wetland and water (Table 2.1). In 2016, 4% of the country was used for growing crops and tame or seeded pastures and in 2015, 0.6% was covered by built-up and artificial surfaces used for settlements, transportation and other infrastructure.

Freshwater covers an estimated 1.3 million km²—13% of the country’s landscape including the Great Lakes. The area of these water courses and water bodies fluctuates depending on the season and weather conditions. For example, in summer, snowmelt contributes to the formation of shallow lakes in tundra areas, while in the Prairies, pothole wetlands that fill with water in the spring may disappear later in summer. Seasonal and inter-annual fluctuations can make it difficult to discern shifts in the extent of freshwater areas. The Great Lakes—the largest freshwater lake system in the world—straddle the Canada–United States border and cover an area of approximately 90,000 km² in Canada.^Note

Canada’s boreal zone is a vast expanse of sub-arctic forest, woodland, heathland, grassland, wetland and water stretching across 5.5 million km² from Newfoundland and Labrador to the Yukon. The vegetation is shaped by the cold climate conditions, with winter temperatures that can consistently reach -40°C and below, and fire—the chief natural disturbance.^Note From north to south, boreal forests transition from forest-tundra zones, to open forests, to closed forest and cover close to 2.8 million km². Spruce (picea) are the dominant genus of trees in the boreal zone, with open spruce-lichen forests providing important habitat for caribou.^Note Other trees include cold-hardy varieties of poplar, birch, fir and pine.^Note Extensive organic wetland areas, known as peatlands, with sporadic and patchy permafrost areas,^Note have formed in lowland areas of the boreal zone, particularly surrounding Hudson Bay and Great Slave Lake. These bogs and fens, covered in sphagnum moss, lichens, shrubs and spruce trees, extend across approximately 1.1 million km² or about 11% of the total area of the country.

A greater diversity of vegetation is found in the cool temperate forests south of the boreal zone that collectively cover approximately 8% of the country. These include the largely coniferous rainforest, dry, montane and subboreal forests in coastal British Columbia and cordilleran British Columbia and Alberta; the Eastern mixed Great-–Lakes and St. Lawrence forests and deciduous Carolinian forests of Central Canada and southwestern Ontario; and the mixed Acadian forest in the Maritimes.^Note

Forests are affected by natural disturbances such as insect infestation, disease, fire and windthrow, as well as by timber harvesting, forest management practices and land use decisions. Much of Canada’s temperate forest and the southern parts of the boreal forest are managed for timber production, with harvesting and regeneration timed to produce a sustainable forest yield as forests mature.^Note Overall, Canada’s forest area is relatively stable—from 1990 to 2018, 0.4% of forests were deforested and converted to other uses, including agriculture, roads, hydro-electric reservoirs and urban areas.^Note

Tundra ecosystems are treeless areas of dwarf shrub and other low-lying sedges, mosses and lichen that have developed north of the boreal zone and in alpine regions at higher elevation. Arctic tundra experiences extremely low winter temperatures and low precipitation and has extensive permafrost soils that store vast amounts of organic carbon. In summer, the active or top layer of this soil thaws, developing into lakes and marshy areas and releasing methane and carbon from decomposing plant material. Arctic tundra, including rocky barrenland, covers an estimated 2.5 million km² of Canada’s North and additional areas of alpine tundra occur at elevation in the Rocky and Coast Mountains ranges. Areas of permanent snow and ice also occur in the Arctic Cordillera and at high elevation in Canadian mountain ranges, covering over 200,000 km² or about 2% of Canada’s total area.^Note

Grassland ecosystems developed south of the boreal zone, in the Canadian Prairie provinces, east of the Rockies and in the dry valleys of southern interior British Columbia. The Prairies also include hundreds of thousands of small wetlands known as Prairie potholes that are important for local hydrology and provide habitat for waterfowl,^Note as well as wooded parkland areas that are a transition area between the grasslands and the boreal forest. The dominant grass and forb vegetation of these grasslands developed under cold and dry climate conditions and was maintained by fire and grazing. These ecosystems are among the most altered in North America, with little of the original grassland remaining.^Note Prairie grasslands developed fertile and humus-rich soils from the extensive plant root systems, though a significant proportion of this soil organic matter was lost during the conversion of grassland to agriculture,^Note now the dominant land use. Much of the wetland area has also been drained and converted to agricultural use. In 2016, 65% of the Parkland Prairies ecoprovince was used for arable agriculture,^Note followed by 60% in the Central Grassland and 54% in the Eastern Prairies, though additional grassland areas were used as natural pasture and rangeland.

Agriculture is also a major land use outside the Prairies, particularly in the Huron–Erie plains and Great Lakes–St. Lawrence Lowlands ecoprovinces, where arable land accounted for 58% and 39%, respectively, of the total area in 2016. It also contributed a significant but smaller share of the Central Boreal Plains ecoprovince (15%) and Eastern Boreal Plains (5%), the Northumberland Lowlands (7%) and Appalachian–Acadian Highlands (5%) in the Maritimes and Georgia Depression (5%) in British Columbia.

Humans are a part of Earth’s ecosystems, exerting substantial pressures and influencing ecosystem processes and functions.^Note Urban development and industrial activity can dramatically alter the surrounding landscape. For example, land use change around cities is a direct driver of change causing permanent shifts from forest or agro-ecosystems to urban areas. Most settlement and human infrastructure is located in the south of the country, where the majority of people live (Table 2.2). Only seven ecoprovinces had a population of over one million people in 2016 and much of the country remains sparsely populated. Other built-up area is associated with resource extraction and industry use, including mines and oil and gas infrastructure.

In 2015, 62,600 km² of Canada’s landscape was built-up and artificial surface associated with settlements and infrastructure, up 11% from 56,400 km² in 2000.^Note

Ecoprovinces with the highest percentage of built-up and artificial surfaces are the Huron-Erie Plains at 19%, Georgia Depression at 11% and the Great Lakes–St. Lawrence Lowlands at 10% in 2010. These three ecoprovinces include Montréal, Ottawa, Vancouver, Toronto and other large urban population centres and are home to over 62% of the population of Canada. Populations in urban areas rely heavily on ecosystem services generated elsewhere, as cities themselves occupy relatively little area while housing the majority of the population. In 2016, 81% of the population lived in population centres, the majority in large urban centres with a population greater than 100,000.^Note

The largest increases in built-up and artificial surfaces at the ecoprovince-level from 2000 to 2010 occurred in the Southern Boreal Shield, Central Boreal Plains and Great Lakes–St. Lawrence ecoprovinces. These three ecoprovinces accounted for more than half of the increase in built-up area over this period.

2.2 Marine and coastal ecosystems

Defining the extent of ecosystems in the ocean can be complicated. In all but the shallowest waters, surveying the ocean bottom in detail requires either diving or sending camera probes, though technologies such as sonar are increasingly being explored. Parts of the ocean are less well known than the surface of the moon because of the high pressures and almost freezing temperatures experienced at depth.^Note Canada’s EEZ is approximately 5 km deep at its deepest, presenting a major challenge in mapping our ocean territory. Our knowledge about marine and coastal ecosystems—their locations, size and condition—is incomplete, particularly in arctic regions.

Measuring the depth of water above the seafloor—known as bathymetry—indicates the potential location of different types of ocean ecosystems. Sunlight, which plays a large role in determining where animals, plants and other biota live, will not penetrate much further than 200 m,^Note though small amounts may reach as deep as 1,000 m. Other bottom characteristics such as terrain ruggedness, slope and substrate can indicate favourable locations for different ocean habitats ^Note and vegetation covers, as well as susceptibility to harm from changing ocean conditions, large storm events or human activities and modifications.

Areas with water depths down to 200 m, in particular shallower coastal areas, are the main regions of the ocean capable of supporting photosynthesizing plants. Many important ecosystems, such as saltmarshes, seagrass meadows and kelp forests are mainly found in coastal areas with water depths of 50 m or less (Map 2.2 and Table 2.3). While not all coastal ecosystems are fully mapped, estimates of saltmarsh extent indicate that at least 1,114 km² of these intertidal ecosystems exist, while seagrass meadows and kelp forests respectively cover an estimated 1,429 km² and 634 km² of seabed (Map 2.3 and Table 2.4). These ecosystems are biodiversity hot spots and important carbon sinks.^Note

Most of the world’s major fisheries, such as herring, anchovy, sardine and cod, also occur in waters in the most shallow (epipelagic) depth range of 0 to 200 m. Almost 47% of the extent of Canada’s EEZ has seafloor depths in this range, while another 25% can be classed as mesopelagic, with depths from 200 m to 1000 m. Waters at this depth have diminishing levels of light as depth increases and host a diverse range of species adapted to a low-light environment.

Areas with deeper (bathypelagic) waters have depths between 1 km and 4 km. The seafloor in these areas receives no sunlight and experiences higher pressures and colder temperatures. Some cold-water corals grow at depths up to 2.5 km on the East Coast of Canada and can be hundreds of years old, though they can also be found in shallower waters on both the east and west coasts.^Note Coral reefs are important ecosystems for biodiversity, providing a home for a diverse population of fish and bottom dwellers. These reefs are fragile and susceptible to damage from human activities, such as fishing and oil extraction, as well as climate change due to the temperature requirements of some species.^Note Squid, large whales and octopuses can also be found at these depths. Slightly more than a quarter of Canada’s EEZ has depths in this zone, in particular the Offshore Pacific and Arctic Basin marine ecoregions.

On the East Coast there are small areas of very deep (abyssalpelagic) waters with depths greater than 4 km in the offshore areas of the Scotian Shelf and Newfoundland Shelf marine ecoregions. These regions cover 2% of Canada’s total EEZ. These deeper areas sometimes also have shallower regions known as sea knolls or seamounts that can occur in areas of high ruggedness and slope. Sea knolls and seamounts can be rich in biodiversity since the mixing of water and nutrients that occurs at these locations provides food for many species and are therefore a potential focus for conservation efforts.^Note The Pacific waters in Canada’s EEZ have the highest proportion of rugged territory and thus a higher density of seamounts and sea knolls (Table 2.5).

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