It was originally dominated by temperate deciduous forest growing mostly on limestone covered by glacial till.

To deal with the differences in names between Canada and the United States, the Commission for Environmental Cooperation has produced a continental atlas.

In this atlas, the Mixed Wood Plains is a Level II Ecoregion 8.1, which includes the above areas within Canada, as well as adjoining parts of the United States.

At its western end, it encompasses all of Southwestern Ontario, and is bounded by three Great Lakes and their connecting waterways.

Another is the Frontenac Axis, an exposure of Canadian shield rocks that extends south to the St. Lawrence River near Kingston, creating the Thousand Islands.

In south-central Ontario, the ecologically important and politically sensitive Oak Ridges Moraine is a major feature.

[10] Some of the most fertile soil in Canada is located in this ecozone, in which the Holland Marsh has come to be known as "Ontario's vegetable basket", and the Niagara Peninsula is the most productive wine region in the country.

[1] The Lake Erie Lowland corresponds roughly to Site Region 7E,[5] and to the more general term "Carolinian Forest.

"[10] This ecozone can be further subdivided into two ecoprovinces:[11] The climate of the Mixedwood Plains is characterized by warm to hot summers and cool winters.

The Great Lakes and Saint Lawrence River have a significant moderating effect in this ecozone, which is in a major North American storm belt.

Within Canada, these forest types are often referred to as the 'Carolinian zone' owing to the many southern plants and animals that reach their northern limits here.

The wetlands of the St. Lawrence and Ottawa River have a diverse array of vegetation types as well, although these have been damaged by the construction of power dams and locks for shipping.