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Ecozone+ Basics

The Mixedwood Plains Ecozone+, shown in Figure 1 and summarized in Table 1, is the most southerly Canadian ecozone+encompassing the provinces of Ontario and Quebec south of the Precambrian Shield.5 It contains only 1.2% of Canada’s land mass (one of the smallest ecozones+) but has 53% of the country’s population making it the most human-dominated ecozone+ in the country. The deep soils and moderate climate of the ecozone+ (by Canadian standards) have made it an attractive place for settlement. The population density, 140 people/km2, is an order magnitude higher than that found in the next most populated ecozone+ (Pacific Maritime at 16 people/km2).10 The rapid population growth is projected to increase by 30% between 2006 and 2031.7 The Mixedwood Plains is the second most fragmented ecozone+ in Canada.8 The main stresses are habitat loss and fragmentation, the spread of invasive species, pollution, and climate change.

Table 1 Mixedwood Plains Ecozone+overview.+.
Area / TypeDetails
Size of area118,870 km2
Topographyand Geology

Extremely flat to gently rolling plains dominate most of the ecozone+. Broken up by several striking physical features, most notably the rugged terrain of the Niagara Escarpment which runs from Niagara Falls to the northern tip of the Bruce Peninsula and Manitoulin Island. Contains an extensive system of waterways draining into the St. Lawrence River and the Great Lakes.Formed by mix of Precambian mountain building episodes and more recent glacial advances and retreats. Includes five distinct geologic units:

  • Frontenac Arch – ridge of Precambrian bedrock with shallow soils in the Kingston Area; southerly extension of the Canadian Shield. 
  • Niagara Escarpment – long, linear feature composed of Silurian bedrock; includes bare bedrock uplands and steep bedrock cliffs. 
  • East of Frontenac Arch and extending east to Québec City – deep soiled, flat marine clay plains deposited by the Champlain Sea.
  • Between the Escarpment and the Frontenac Arch – series of large ridges formed by the growth and melting of glaciers (Oak Ridges Moraine is the best-known of these features).

West of the Niagara Escarpment – deep soiled, broad, flat clay plains deposited by freshwater glacial lakes.

ClimateWarm summers (average temperature 17°C) and cool winters (average temperature –5°C) moderated by surrounding water bodies. Annual precipitation ranges from 720 mm to 1,000 mm. Prone to highly changeable weather due to location in one of the major storm tracks of North America.
River basins

Thames River into Lake St. Clair
Grand River into Lake Erie
Trent River into Lake Ontario
St. Lawrence River and its tributaries flowing into the Atlantic Ocean:

  • Ottawa River;
  • Chateauguay River;
  • Richelieu River;
  • Sainte Francois River;
  • Saint-Maurice River;
  • Yamaska River;
  • Becancour River; and
  • Chaudière River.
SettlementMost heavily populated ecozone+ in Canada. Includes the major metropolitan areas of Toronto, Montréal, and Ottawa. Other major cities include Quebec City, Hamilton, and London.
EconomyDiverse economy of manufacturing, services, and agriculture.
DevelopmentExtensive urban development in both the Golden Horseshoe of Ontario and around Montréal, Quebec. Extensive road networks. Agricultural intensification is occurring throughout the ecozone+ particularly in the marine clay plains of St. Lawrence Lowlands of Quebec and the lacustrine clay plains of southern Ontario.
National/global significanceThree national parks: Point Pelee; Bruce Peninsula; and Thousand Islands.
Thirteen National Wildlife Areas: St. Clair; Big Creek; Long Point; Mohawk Island; Wye Marsh; Wellers Bay; Scotch Bonnet Island; Prince Edward Point; Mississippi Lake; Lac Saint-François; Îles de la Paix; Îles de Contrecoeur; and Cap Tourmente.
Eight Ramsar sites: Point Pelee; St. Clair; Long Point; Minesing Swamp; Matchedash Bay; Mer Bleue Conservation Area; Lac Saint-François; and Lac Saint Pierre.
Seventy-two Important Bird Areas.
Five UNESCO biosphere reserves: Niagara Escarpment; Frontenac Arch; Long Point National Wildlife Area; Lac St. Pierre; and Mont Saint Hilaire.
The Great Lakes and St. Lawrence River are a major entry point for invasive non-native species to both Canada and the United States.

Jurisdictions: The Mixedwood Plains Ecozone+ in Canada includes the southernmost parts of the provinces of Ontario and Quebec. Approximately 73.2% of the ecozone+ is located in Ontario and 26.8% in Quebec. Major Aboriginal cultural groups represented in this ecozone+ include the Ojibway (Chippewa), Haudenosaunee (Iroquois), Deleware, and Potawatomi.

Population: Between 1971 and 2006, the human population of the Mixedwood Plains Ecozone+ increased from approximately 11 million people to over 16 million people (Figure 2).

Figure 2. Human population of the Mixedwood Plains Ecozone+, 1971–2006.
Long description for Figure 2
This bar graph shows the following information:
YearNumber of people

Source: adapted from Statistics Canada, 20099

Land cover: Based on 2005 remote sensing data, cultivated land was the predominant land cover type representing 68% of the total area, followed by forest at 25%. Urban lands comprised 4% of the ecozone+ (Figure 3).

Figure 3. Distribution of major land cover types in the Mixedwood Plains Ecozone+ as delineated by remote sensing, 2005.
Long description for Figure 3

Cette carte et ce graphique à bandes empilées indiquent la répartition de quatretypes de couvertures du sol en importance. L’écozone+ est recouverte par 25 % de forêt, 3 % d’arbustaies, 68 % sont cultivés et 4 % sont urbains. Les eaux intérieures sont également indiquées sur la carte, mais le pourcentage de couverture n’est pas donné. Les zones forestières sont prédominantes le long de l’extrémité nord-ouest de l’écozone+, de l’île Manitoulin à la rivière des Outaouais, et à l’est de la rivière Richelieu. La plupart des arbustaies se retrouvent dans le centre de l’écozone+, longeant la zone forestière, et la majorité de la zone urbaine se trouve aux alentours de Toronto et de Montréal. Les terres cultivées s’étendent à l’ensemble de l’écozone+, prédominantes dans le sud-ouest et le long du fleuve Saint-Laurent.

Source: Ahern et al., 2011 8 using data from Latifovic and Pouliot, 200510

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Landscape vignettes

Downtown Toronto skyline

Downtown Toronto skyline
Photo Credit: Barry Roden, Cabinet Office, Government of Ontario. Photo may not be reproduced without the permission of the rights holder.

Marsh, Lake St. Clair

Marsh, Lake St. Clair
Photo Credit: Allen Woodliffe, OMNR. Photo may not be reproduced without the permission of the rights holder.

Black oak savannah in Rondeau Provincial Park

Black oak savannah in Rondeau Provincial Park
Photo Credit: Allan Woodliffe, OMNR. Photo may not be reproduced without the permission of the rights holder.

Maple-oak forest, Skunk’s Misery

Maple-oak forest, Skunk’s Misery
Photo Credit: Allen Woodliffe, OMNR. Photo may not be reproduced without the permission of the rights holder.

Uxbridge, Ontario area

Uxbridge, Ontario area
Photo Credit: Doris Krahn, OMNR, 2008. Photo may not be reproduced without the permission of the rights holder.

Carden Alvar

Carden Alvar
Photo Credit: Wasyl Bakowsky, OMNR. Photo may not be reproduced without the permission of the rights holder.

Newly ploughed agricultural field on Îles d’Orleans, Quebec

Newly ploughed agricultural field on Îles d’Orleans, Quebec
Photo Credit: © / A. Salsera (AnikaSalsera)

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