New England-Acadian forests

• Category: Forest Biomes.
• Geographic Location: North America.
• Summary: The New England-Acadian Forests ecoregion is noted for encompassing a transition zone between two distinct vegetation types across a geologically complex area. It also is home to diverse, unique ecosystems, including cranberry bogs and glacial-remnant lakes.

The New England-Acadian forests are coastal forest communities along the North Atlantic Ocean that are best characterized as the transition zone between boreal forests to the north and temperate deciduous forests to the south. The biome consists of temperate broadleaf and mixed forests with an array of habitats on the hills, mountains, and plateaus of New England in the northeastern United States, along with the Maritime Provinces of eastern Canada.

Encompassing most of Maine down to northwestern Massachusetts, through Vermont and New Hampshire, as well as most of Nova Scotia, and parts of Quebec and New Brunswick in Canada, the region was once covered by glaciers 9,843 feet (3,000 meters) thick. The landscape was left with a visually striking variety of topographic features. Among these are broad sweeping valleys, glacial erratics, striations, glacial potholes and kettle ponds, cobblestone beaches, and marine-deposited clay soils.

The climate of this region consists of humid summers and cool winters, and is characterized as a cool humid continental-marine climate.

Natural Features

The New England-Acadian Forests biome contains a vast array of habitats and natural features, including beaches and shorelines, intertidal and subtidal zones along the Atlantic, mountains, marshes, and swamps. Each of these has associated animals and plants, which sometimes also give structure to the ecosystems they inhabit. The Acadian forest system also is known for its distinct assortment of unique ecological features, including serpentine rocks, raised peat bogs, ribbed fens, and raised coastal peatlands. The forest is home to Acadia National Park, a region noted for rugged, breathtaking landscapes.

The Atlantic Ocean can be a powerful driver of forest ecosystems, especially in New England, where the maritime currents provide a significantly moist and humid environment. Trees along the coast are subjected to higher concentrations of salts, which can lead to interesting physical changes on plant communities. Beaches and shorelines provide a transition from marine to terrestrial ecosystems, fundamentally bridging two major ecotypes.

Intertidal and subtidal zones are defining ecosystems within the New England-Acadian forests because they support numerous marine, estuarine, and freshwater organisms. The interactions between these organisms and their environments are important to understand, especially as their diversity is at risk as ocean levels rise and coastal habitats are exploited. These zones are interesting biologically, as estuarine environments (where salty and freshwater mix) can be crucial habitats for commercially important fish and other aquatic species. Estuaries serve as buffers for the transition from aquatic and marine to terrestrial environments.

Acadian forests are found in the White Mountains of New Hampshire, the Green Mountains of Vermont, and north of Mount Katahdin in Maine. Mountains provide topographic relief, and with this variation, the transitions among different forest community types become more apparent. At increased elevations, more boreal forest species appear, while deciduous species dominate the lower elevations.

Wetland communities feature soil that is inundated with water, including such wetland types here as ribbed fens and peat bogs. Marshes have areas of low-lying land that are flooded in wet seasons or at high tide, and typically remain waterlogged. The dominant vegetation in these habitats consists of nonwoody plants and grasses.

Swamps are flooded low-lying areas usually containing woody plants and trees such as tamarack and black spruce. Bogs have wet, spongy ground, usually comprising various sphagnum moss species, that is highly acidic and contains dead plant material that is decaying slowly. This soil is compressed over time into peat. Bogs can support a variety of plant species, including cranberries (Vaccinum macrocarpon), bog laurel (Kalmia polifolia), Labrador tea (Ledum groenlandicum), and sweet gale (Myrica gale).

Vegetation

The New England-Acadian Forests biome is home to more than 30 tree species distributed across this varied topographic backdrop. It will be an important migration zone as climate changes and tree populations effectively migrate poleward in an effort to track their ideal climates as global warming accelerates. Many species are currently at their northern range limit in the Acadian forests, including sugar maple (Acer saccharum) and American beech (Fagus grandifolia).

The forests are composed of several main forest cover types: northern hardwoods, spruce-fir, boreal, and old-growth forests. Each of these supports a different community of plants and animals.

Northern hardwoods trees of the Acadian forest include sugar maple, yellow birch (Betula allegheniensis), American beech, balsam fir (Abies balsamea), and eastern hemlock (Tsuga canadensis). Associated and less common species include red spruce (Picea rubens), red oak (Quercus rubra), white ash (Fraxinus americana), white pine (Pinus strobus), ironwood (Ostrya virginiana), and striped maple (Acer pensylvanicum).

The understory is largely comprised of spring ephemerals, yellow trout lily (Erythronium americanum), and Carolina spring beauty (Claytonia caroliniana), as well as club mosses (Lycopodium spp.), Bush honeysuckle (Diervilla lonicera), and blueberry species (Vaccinium spp.). Soils within northern hardwoods forests are generally nutrient-rich loams that promote diverse understory species, especially the spring ephemeral flowers, which disappear as soil quality declines.

The spruce-fir forests are the most abundant forest cover type throughout the biome. The overstory of spruce-fir forests is dominated by red spruce, white spruce (Picea glauca), and balsam fir. Common associated tree species include black spruce (Picea mariana), eastern hemlock (Tsuga canadensis), American larch (Larix laricina), and birch species (Betula spp.). The understory in spruce-fir forests can be fairly sparse, but includes herbaceous vegetation and shrubs such as trillium (Trillium spp.), blue-bead lily (Clintonia borealis), hobblebush (Viburnum latanoides), trailing arbutus (Epigaea repens), and Canada mayflower (Maianthemum canadense). Soils within spruce-fir forests tend to decompose more slowly, and are more acidic and nutrient-poor than the soils of northern hardwoods communities. Spruce-fir also is commonly associated with bog communities, which are based on sphagnum moss as the dominant ground cover.

While boreal forests generally are not common in this biome, they are the forest type at one edge of the greater transition zones. Known as the taiga biome, the boreal forests extend throughout the northern reaches of North America and similar latitudes in Eurasia. The overstory is largely low-diversity and centers on black spruce, white spruce, and American larch. Common associated species include pines (Pinus spp.), balsam fir, aspens (Populus spp.), and eastern hemlock (Tsuga canadensis). The understory community depends largely on the nutrient-poor soils of the boreal region, but generally consists of hardy evergreens, especially mosses and bryophytes, although some ferns are also found there. The boreal forest overstory is common in bog settings, similar to the spruce-fir forest type.

The New England-Acadian forests also contain old-growth forest communities. These can vary greatly in composition and structure, but generally present complex structural features indicative of old age. New England old-growth forests generally have large standing dead trees called snags and great biological diversity. The Acadian forests ecoregion contains old-growth eastern hemlock, red spruce, and Atlantic white cedar forests, among other species. These habitats are largely recognized for their importance in preserving biological diversity and their unique structural features; they recently gained attention for their potential to sequester more carbon than second-growth forests, which has important implications in combatting global climate change. Some scientists consider the lack of human-based disturbances critical for old-growth forests, but with global climate change, most ecosystems will be indirectly affected by human actions, even if not through the use of a chainsaw.

Biodiversity

The biome supports diverse animals, from well-known megafauna to rare butterfly populations. Common mammal species include the white-tailed deer (Ocodoileus virginianus), American black bear (Ursus americana), moose (Alces alces), fisher (Martes americana), and muskrat (Ondatra zibethica).

Two wide-ranging species that inhabit the biome and are of concern to scientists as changes from climate change occur are the American marten (Martes americana) and the Canada lynx (Lynx canadensis). The lynx was listed as threatened under the Endangered Species Act in 2000. The cat's fate is closely tied to that of the snowshoe hare (Lepus americanus), which makes up 75 percent of its winter diet.

Common bird species include the red-breasted nuthatch (Sitta canadensis), golden-crowned kinglet (Regulus satrapa), and several warbler species. Two species of interest here include bog turtles and bald eagles (Haliaeetus leucocephalus), which tend to nest in the tall white pines. This forest type supports more than 200 bird species overall, and is considered one of the 20 most diverse ecoregions in North America.

Threats and Conservation

One of the greatest threats to the New England-Acadian forests is global warming. Land fragmentation and construction practices also have huge effects on the biome. Compartmentalizing of land parcels breaks up the connectivity and flow within ecosystems, and can lead to species and population decline for many of them by limiting habitat, resources, and gene flow among populations.

Anthropogenic needs for paper and forest products continue to put additional pressures on forest ecosystems around the globe, and the forests in New England are no exception. The biggest threats to this ecosystem are those of human actions. Additionally, nonnative species (such as the invasive purple loosestrife) and pests (such as the hemlock woolly adelgid) threaten native forest communities, and can have long-term effects on structure and community composition within the forests.

Bibliography

“Acadian Forest.” New England Forestry Foundation, newenglandforestry.org/forest-management/exemplary-forestry/acadian-forest/. Accessed 21 Nov. 2024.

Bateson, Emily M. “Two Countries, One Forest—Deux Pays, Une Forêt: Launching a Landscape-Scale Conservation Collaborative in the Northern Appalachian Region of the United States and Canada.” Conservation Practice at the Landscape Scale 22, no. 1, (2005).

Braun, E. Lucy. Deciduous Forests of Eastern North America. Caldwell, NJ: Blackburn Press, 1950.

Eyre, F. H., ed. Forest Cover Types of the United States. Bethesda, MD: Society of American Foresters, 1980.

Noseworthy, Josh, and Thomas M. Beckley. "Borealization of the New England-Acadian Forest: A Review of the Evidence." Environmental Reviews, vol. 28, no. 3, 2020. DOI: 10.1139/er-2019-0068. Accessed 21 Nov. 2024.