Abstract for CM742

Eastern Canadian Temperate Deciduous Forest
Forêts décidues de la zone tempérée de l’Est du Canada

CM742 describes the upland temperate forests of southern Ontario as well as the southwestern portion of Quebec. Forest canopies are primarily composed of cold-deciduous broad-leaved species. Anthropogenic disturbance is the dominant factor in determining forest composition, dynamics and distribution. Windthrow, ice loading and insect infestations are the most widespread forms of natural disturbance; fire is generally not a natural disturbance factor. Dominant tree species include sugar maple (Acer saccharum), red maple (A. rubrum), white ash (Fraxinus americana), American basswood (Tilia americana) and American beech (Fagus grandifolia). Eastern hop-hornbeam (Ostrya virginiana), black cherry (Prunus serotina) and northern red oak (Quercus rubra) are common canopy associates throughout the range; eastern white pine (Pinus strobus) is occasional. Balsam fir (Abies balsamifera), yellow birch (Betula alleghanensis), eastern hemlock (Tsuga canadensis), eastern white cedar (Thuja occidentalis) and white spruce (Picea glauca) are companion species on cooler sites, especially in the northern portion of the range. Hickories (Carya spp.), white oak (Quercus alba) and blue-beech (Carpinus caroliniana) are more common on warmer sites and in southern parts of the range. Depending on overstory and site conditions, understory shrub and herb layers vary from dense to sparse. Shrub layers are typically rich in regenerating maples and/or other broad-leaved tree species, together with cold-deciduous broad-leaved shrubs and vines such as alternate-leaved dogwood (Cornus alternifolia), eastern prickly gooseberry (Ribes cynosbati), Canada fly-honeysuckle (Lonicera canadensis) and poison ivy (Toxicodendron radicans). Typical herb/dwarf shrub species include trilliums (Trillium spp.), hairy Solomon’s seal (Polygonatum pubescens), large false Solomon’s seal (Maianthemum racemosum), wild lily-of-the-valley (M. canadense), Jack-in-the-pulpit (Arisaema triphyllum) and partridgeberry (Mitchella repens). Vernal ephemeral forbs like Carolina spring beauty (Claytonia caroliniana), yellow trout lily (Erythronium americanum) and wild leek (Allium tricoccum) are characteristic of these forests. Numerous native plant species, such as eastern flowering dogwood (Cornus florida), black oak (Quercus velutina), tulip tree (Liriodendron tulipifera) and American ginseng (Panax quinquefolius) reach their northern range limits in the southern portion of the CM742 range.

CM742 occurs in the humid, continental cool temperate climate of eastern Canada, generally characterized by cool winters and moist, warm to hot summers. Mean annual temperatures vary from 5°C to >9°C. Mean annual precipitation is >900 mm throughout the range; rainfall significantly exceeds snowfall. Regional geologic and topographic features of the St. Lawrence Lowlands physiographic region produce a mostly subdued topography with low relief, except in the west-central part of the range where the cliffs of the Niagara Escarpment overlook the plains. All parts of the region experienced late Pleistocene glaciation; soils are mostly calcareous Luvisols and Brunisols developed in glacial surficial materials. Two subtypes distinguish regional variation within this Macrogroup. Subtype CM742a [Warm Eastern Canadian Temperate Deciduous Forest] describes forests of warmer sites, mostly near Lake Erie, that are dominated by sugar maple with a floristic assemblage that reflects deciduous forests south of the Great Lakes. CM742b [Cool Eastern Canadian Temperate Deciduous Forest] describes maple-beech-basswood dominated forests that have greater conifer content and occur from Lake Huron eastward into the St. Lawrence valley of southwestern Quebec.