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St. Lawrence Lowlands

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About the St. Lawrence Lowlands

The St. Lawrence Lowlands are a region extending from the northern part of upstate New York, into Ontario ond Quebec, and located along the St. Lawrence River. More of the region is located within Canada.

Much of this region used to be a glacial lake; the terrain includes a broad, level valley and plains, with scattered low ridges. Elevations range from 177-600ft, with limited local relief from 40-100 ft. The area is underlain by glacial lake deposits of sand, silt, and clay, with some glacial till. The original rock that these deposits were made from was sandstone in some areas, and limestone in others.

This region has a humid continental climate. The river, which is quite wide and goes through a series of lakes of varying sizes, slightly moderates the climate, but much less so than Lake Ontario moderates the regions to the southwest. Precipitation is markedly lower here than regions south and west, ranging from 30-42 inches, owing both to lower elevation and the absence of lake-effect precipitation. The growing season ranges from 120-140 days.

This region was originally almost entirely forested, except on open wetlands, but most of the forest has been cleared for agriculture. Remaining forest types vary considerably on different sites. Clay soils are dominated by sugar maple, American beech, and eastern hemlock. Sandy soils support black oak, northern red oak, eastern white pine, pitch pine, and red maple. Wetland forests consist of red maple, swamp white oak, white ash, and American elm. In most of the region, forests are small and highly fragmented, but there are some larger tracts of forest on the U.S. side of the region, as well as southwest of Quebec. Brasher Falls State Forest (New York) is one of the largest tracts of public forest land here.

Agriculture here dates to the late 18th century. More recently, the area has experienced significant urbanization as well. Agriculture is still the dominant land use here. There is dairy farming and production of livestock, hay and other forage crops, grain, and potatoes. The Canadian side of this region is quite populous. Major cities here include Montreal and Quebec; the U.S. side of the region is sparsely-populated; even the smaller city of Cornwall is located entirely on the Canadian side of the border.

This region is bordered to the southeast by the more upland Upper St. Lawrence Valley and to the southwest by the Ontario Lowlands.

Plant Lists & In-Region Search

We do not yet have data to generate plant lists for a region as fine-tuned as this one. However you can move up to the broader Eastern Great Lakes Lowlands and generate lists for that region: native plants or all plants. Or search that region's plants here:


1. Bryce, S.A., Griffith, G.E., Omernik, J.M., Edinger, G., Indrick, S., Vargas, O., and Carlson, D. "Ecoregions of New York (Poster)", U.S. Geological Survey (2010) Web.