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This ecoregion includes lowland areas of New York and Vermont surrounding the Adirondacks, portions of Quebec along the St. Lawrence River, and much of southern Ontario between Lake Ontario and Lake Huron/Georgian Bay. Suburban development and pollution of the St. Lawrence have severely harmed natural areas here, and less than 5 percent of the ecoregion remains as intact habitat. This ecoregion is characterized by warm summers and cold, snowy winters that are milder to the south. In the Canadian portion of the ecoregion, the climate ranges from humid mid cool temperate in the south to humid high cool temperate in the northeast. The mean annual temperature ranges from 4.5°C to 6°C, mean summer temperature is approximately 16°C, and the mean winter temperature ranges from -4.5°C to -7°C. Mean annual precipitation ranges from 700-1000 mm. Areas to the lee of the Great Lakes, both in the United States and Canada, lie in major snowbelt areas (ESWG 1995). The Eastern Great Lakes forests lie between the boreal forests and the broadleaf deciduous zones and are therefore transitional. Part of these forests consist of a few coniferous species (mainly eastern hemlock (Tsuga canadensis) and pine (Pinus spp.) and a few deciduous species, mainly yellow birch (Betula alleghaniensis), sugar maple (Acer saccharum), red maple (Acer rubrum), red oak (Quercus rubra), eastern hemlock, and American beech (Fagus grandifolia); the rest is a mosaic of pure deciduous stands in favorable habitats with good soils, and pure coniferous forests in less favorable habitats with poorer soils. In the northeast, beech is restricted to warmer sites. Drier sites contain red oak and red (Pinus resinosa) and white pine (P. strobus), as well as eastern white cedar (Thuja occidentalis). Moist sites are dominated by red maple, elms (Ulmus spp.) eastern cottonwood (Populus deltoides), and ashes (Fraxinus spp.). Eastern white cedar occurs in wet depressions and near streams. Early successional species include white pine, quaking aspen (Populus tremuloides) and paper birch (B. papyrifera). Pine trees are often the pioneer woody species that flourish in burned-over areas or on abandoned arable land. Fires started by lightning are common in this ecoregion, particularly where soils are sandy and there is a layer of dry litter in summer (Flader 1983). The St. Lawrence Lowlands are underlain by carbonate-rich Palaeozoic bedrock. The landscape is a mix of bedrock outcrops and deeper marine and lacustrine clay deposits. The southern region is divided by the Niagara Escarpment, which extends northeast to Manitoulin Island. The area to the west of the escarpment slopes to the southwest in rolling topography, and the area to the east of the escarpment rises from Lake Ontario north to Georgian Bay. Consequently, most of this ecoregion has low relief. Lakes, poorly drained depressions, morainic hills, drumlins, eskers, outwash plains, and other glacial features are typical of the area, which was entirely covered by glaciers during parts of the Pleistocene. The greatly varying soils include peat, muck, marl, clay, silt, sand, and gravel (ESWG 1995).
This ecoregion contains numerous rare ecological or evolutionary phenomena. Pronounced is the mosaic of freshwater marshes and dunes, bogs and fens, hardwood and conifer swamps as well as the rare and unique alvar communities (also called pavement barrens) restricted primarily to this ecoregion in North America. These alvar communities support a suite of prairie species that reach the eastern edge of their range here. These alvar communities are the most extensive in the world, and represent a habitat type that is globally endangered. Elsewhere in the world, such communities are known to occur only on islands in the Baltic Sea of Sweden and in Estonia (Couchiching Conservancy 1996). Other rare phenomena include ancient eastern white cedar trees growing on the exposed limestone cliffs of the Niagara escarpment. Some trees have been aged at 700 to 800 years, making them among some of the oldest in eastern North America. The St. Lawrence lowlands of Quebec are the most northeastern distribution of many plant species, and the fresh tidal wetlands along the St. Lawrence are high in species endemism. The Eastern Great Lakes Lowland forests are a moderately rich example of temperate broadleaf and mixed forests. The mosaic of forest types and habitats supports 225 bird species, making these forests the second-richest ecoregion within this major habitat type, and among the 20 richest ecoregions in the continental United States and Canada. Many large mammals, such as black bear (Ursus americanus), moose (Alces alces), and wolf (Canis lupus) have been extirpated from much of this region. White-tailed deer (Odocoileus virginianus), coyote (Canis latrans), snowshoe hare (Lepus americanus), chipmunk (Tamias striatus), red (Tamiasciurus hudsonicus) and eastern gray squirrel (Sciurus carolinensis) represent a few of the more common species. Some characteristic breeding birds include northern cardinal (Cardinalis cardinalis), green-backed heron (Butorides virescens), mourning dove (Zenaida macroura), eastern screech owl (Otus asio), wood thrush (Hylocichla mustelina), pileated woodpecker (Dryocopus pileatus), wood (Aix sponsa) and American black duck (Anas rubripes) (ESWG 1995). Habitat loss Over 95 percent of the habitat in this ecoregion has been lost to suburban development and pollution of the St. Lawrence. Much of the remaining habitat consists of wetlands or abandoned farmlands undergoing reforestation. In some locations, recovery of abandoned agricultural land is beginning to occur, but these lands remain unprotected. Other areas continue to be converted to agriculture or are succumbing to widespread urban sprawl throughout this ecoregion. Remaining Blocks of Intact Habitat This ecoregion contains no blocks of intact habitat more than 250 km2 in area. Important blocks include:
Degree of Fragmentation The Eastern Great Lakes Lowland Forests are highly fragmented, with effectively no connectivity in most areas and little core habitat due to edge effects. The individual fragments and clusters that remain are highly isolated, and the intervening urban and suburban landscape precludes dispersal for most taxa. Degree of Protection None of the protected areas in this ecoregion exceed 250 km2. Important areas include:
Types and Severity of Threats Development, particularly construction of summer homes and suburbanization, pose the greatest conversion threat to the Eastern Great Lakes Lowland forests. Montreal (population greater than 2 million), Ottawa (population greater than 700,000) and Quebec City (population greater than 700,000) are some of the larger urban centres. Suburbs of other urban centres such as Toronto, Ontario, Syracuse, and Albany, N.Y. spill out into this region as well, despite their city centres being in adjacent ecoregions. Widespread farming occurs on much of the rest of the landscape (along with smaller manufacturing centres). Principal crops are corn, grains, soybeans and apple orchards. Degradation due to pollution, however, is a more serious concern. The St. Lawrence is one of the most polluted waterways in North America, with high levels of mirex, PCBs, DDT and its derivatives (Colborn et al. 1990). In spite of this, the area still supports a diversity of faunal populations including breeding populations of common and black terns, caspian terns, and least and American bittern. The shoreline of Lake Ontario and the St Lawrence is important migratory bird habitat including land birds, shore birds and waterfowl.
 Relationship to other classification schemes The Eastern Great Lakes Forests ecoregion represents a subdivision of Bailey’s Laurentian Mixed Forest Province. This ecoregion extends Omernik’s Erie/Ontario Lake Plain to the north and west of Lake Ontario. The forests north of the lake are distinct from those along the lake’s southern edge so we chose to classify all forests south of Lake Ontario as part of a single ecoregion, the Southern Great Lakes Forests [NA0414]. In Canada, the Eastern Great Lakes Lowland Forests are distributed through east-central Ontario and southern Quebec. This region encompasses the St. Lawrence Lowlands, the Frontenac Axis, and the Manitoulin-Lake Simcoe area (TEC 132, 133, and 134) (ESWG 1995). This ecoregion includes a part of the Niagara section of the Deciduous forest region 1, and Great Lakes-St. Lawrence regions 1-3 and 4c: Huron-Ontario, Upper St. Lawrence, Middle St. Lawrence, and Middle Ottawa (Rowe 1972). Prepared by: Kevin Kavanagh, Marni Sims, Tim Gray, Nathalie Zinger, Louise Gratton.This text was originally published in the book Terrestrial ecoregions of North America: a conservation assessment from Island Press. This assessment offers an in-depth analysis of the biodiversity and conservation status of North America's ecoregions. All text by World Wildlife Fund © 2001 For more general information on this ecoregion, go to the WildWorld version of this description.
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