Abstract for CM744

Acadian Temperate Forest
Forêts acadiennes de la zone tempérée

CM744 describes the upland temperate forests of New Brunswick, Nova Scotia, Prince Edward Island and a small part of the Gaspé peninsula in Quebec. Forest canopies can be evergreen coniferous, cold-deciduous broad-leaved, or a conifer–broad-leaved mixture. Anthropogenic disturbance is the dominant factor determining contemporary forest composition and dynamics. Windthrow, ice loading and insect infestations are the most widespread forms of natural disturbance; overall, fire is not a significant disturbance factor. Dominant tree species include balsam fir (Abies balsamea), red maple (Acer rubrum), paper birch (Betula papyrifera), yellow birch (B. alleghaniensis), red spruce (Picea rubens), sugar maple (Acer saccharum) and white spruce (Picea glauca). Black spruce (P. mariana) often dominates stands on nutrient-limited sites. Eastern white pine (Pinus strobus), eastern hemlock (Tsuga canadensis) and American beech (Fagus grandifolia) are common canopy associates or dominants in the southern part of the range and at low elevations in the north. Depending on overstory and site conditions, understory shrub and herb layers vary from dense to sparse. In addition to regenerating tree species, understories are generally rich in cold-deciduous broad-leaved shrubs, perennial forbs and ferns. Striped maple (Acer pensylvanicum), velvet-leaved blueberry (Vaccinium myrtilloides) and Canada fly-honeysuckle (Lonicera canadensis) are common shrubs throughout the range. Typical herb/dwarf shrub species include wild lily-of-the-valley (Maianthemum canadense), northern starflower (Lysimachia borealis), yellow clintonia (Clintonia borealis), bunchberry (Cornus canadensis), wild sarsaparilla (Aralia nudicaulis) and common wood-sorrel (Oxalis montana). Wood ferns (Dryopteris intermedia, D. carthusiana, D. campyloptera) are also frequent. The bryophyte layer can be particularly abundant, especially under mature conifer canopies and/or in areas with a very humid climate. The most common bryophyte species include red-stemmed feathermoss (Pleurozium schreberi), stairstep moss (Hylocomium splendens) and three-lobed whipwort (Bazzania trilobata).

CM744 occurs at the eastern extent of humid, cool temperate climatic conditions in Canada. Although the macroclimate is broadly considered continental, the Atlantic Ocean surrounds the CM744 range on three sides generating a pronounced maritime influence. Generally, winters are relatively mild and summers are cool and humid. Mean annual temperatures vary from approximately 3.5°C to 7°C. Mean annual precipitation increases from approximately 1000 mm in central New Brunswick to >1675 mm along the outer Atlantic coast of Nova Scotia. Rainfall significantly exceeds snowfall. Elevation grades from >800 mASL in northern New Brunswick to sea level; much of the range is <200 mASL. Regional geologic and topographic features of the Appalachian physiographic region produce an array of local site conditions. All parts of the range experienced late Pleistocene glaciation; soils are mostly Podzols and Luvisols developed in glacial surficial materials.

Two subtypes characterize regional floristic and ecological variation. Subtype CM744a [Typic Acadian Temperate Forest] describes the typical condition, often including sugar maple, American beech, white pine and eastern hemlock. Subtype CM744b [Cool Acadian Temperate Forest] describes forests of colder climatic conditions that occur at higher elevations and in coastal areas, including greater representation of white spruce, balsam fir, mountain ash and mountain maple.