Northern Hardwood Forests of the Adirondacks

Adirondack Ecological Communities: Autumn colors from the Old Orchard Loop at Heaven Hill (11 October 2015)

Adirondack Forest Communities: The rich tapestry of hardwoods that characterizes the northern hardwood forest is conveniently seen in the autumn, when the orange and yellows of birch and aspen contrast with the orange-reds of maples. Autumn colors from the Old Orchard Loop at Heaven Hill. (11 October 2015).

The northern hardwood forest is the most extensive woodland in the Adirondacks. It occupies the region's best soils and sites, growing on the more fertile soils that make up glacial till. The northern hardwood forest is generally found on the lower and warmer mountainsides – gentle slopes where soils are neither extremely dry nor extremely wet.

The most dominant life form in the northern hardwood forest are deciduous trees, which lose their leaves each fall and are almost completely dormant in the winter months. One of the most striking characteristics of the northern hardwood forest is the extravagant display of fall colors, which result from the loss of green pigment, chlorophyll, as the trees slow down their photosynthesis in the autumn and prepare to enter dormancy for the winters. With the chlorophyll is gone, pigments which were hidden previously become visible, producing the vibrant reds of the Sugar Maple and the golden yellows of the American Beech.

Northern hardwood forests in the Adirondacks can be recognized from afar by the color and pattern of foliage.

In spring, before leaf-out, the grey-brown pattern of unleafed branches contrasts with the somber dark green expanse of conifers both above and below the hardwoods.
In summer, hardwood forests can be distinguished by areas of bright green foliage.
In fall, the oranges, yellows, and reds of deciduous trees stand out against the dark greens of the conifers.

Trees of the Northern Hardwood Forest

The two dominant tree species are Sugar Maple and American Beech, both of which can tolerate more shade than other hardwoods and thrive on deep, fertile, well-drained till. Also present in some areas is Yellow Birch, which requires somewhat more sun and does well on both till and outwash, and Eastern Hemlock. The mix of trees on any given site varies with the elevation, soil, topography, and water table.

Trees of the Adirondacks: Sugar Maple on the Old Orchard Trail at Heaven Hill (24 September 2015).

Trees of the Adirondacks: Sugar Maple leaves turn red, yellow, or orange in autumn, contributing to the brilliant palette of colors seen in September and early October in the Adirondacks. Sugar Maple on the Old Orchard Loop at Heaven Hill (24 September 2015).

The

Sugar Maple

– growing in abundance with Yellow Birch, Eastern Hemlock, American Beech, and Eastern White Pine – is an indicator species for the northern hardwood forest. On those areas most suited for hardwoods, Sugar Maple is the dominant species. This tree can also be found in mixed hardwood-conifer forests. Although the Sugar Maple grows in a wide variety of soils, it does best on deep, well-drained soils. It is rarely found in swamps, because it does not tolerate wet soils.

Sugar Maple is a food source for several wildlife species. White-tailed Deer, Moose, and Snowshoe Hares commonly browse on Sugar Maple trees. Red Squirrels feed on its seeds, buds, twigs, and leaves. Porcupines eat the bark and can girdle the upper stem. A number of birds build nests in Sugar Maples, including American Redstarts, Evening Grosbeaks, Baltimore Orioles, and Northern Cardinals. For several species – including the Cerulean Warbler, Scarlet Tanager, Hairy Woodpecker, and Summer Tanager – the Sugar Maple is one of the preferred trees for foraging for insects.

Trees of the Adirondacks: American Beech trees throughout the Adirondack Mountains are suffering from Beech Bark Disease, which was introduced from Europe. American Beech at the Paul Smith's College VIC (28 July 2012)

American Beech

is the other dominant species in northern hardwood forests of the Adirondacks. It also occurs in mixed hardwoods with Sugar Maple, birch, and hemlock. American Beech trees do best in well-drained upland sites and are not found in wetlands. American Beech trees contribute to the brilliant fall color of the Adirondacks, turning golden yellow or lustrous brown in late September and October, then pale brown in autumn. The leaves remain on the tree well into winter.

Beech nuts are an important source of food for wildlife, including Raccoons, White-tailed Deer, Porcupines, and Foxes, as well as squirrels and chipmunks. Beechnuts are also consumed by Black Bears, who load up on calories for winter hibernation. The American Beech also provides food and nesting sites for a variety of birds. American Beech are used as a nest site by Cooper's Hawks and American Redstarts. American Beech trees provide nest cavities for cavity nesters, like the Wood Duck. Beechnuts are an important food source for Blue Jays, Red-headed Woodpeckers, White-breasted Nuthatches, and Red-bellied Woodpeckers.

Shrubs of the Northern Hardwood Forest

The understory of the northern hardwood forest includes several species of shrub:

Adirondack Shrubs: Hobblebush at the Paul Smiths VIC (11 September 2013).

Shrubs of the Adirondacks: The Hobblebush, so named for its pendulous branches which form obstacles which easily trip (or hobble) walkers, is commonly found in Adirondack hardwood and mixed wood forests. Hobblebush at the Paul Smith's College VIC (11 September 2013).

Hobblebush, which also occurs commonly in mixed wood forests, is a native deciduous shrub which abounds in rich, moist woods throughout the Adirondack Mountains. It produces flat-topped clusters of fragrant white flowers in the spring. The flowers are followed in September by red berries gradually changing to dark blue, and attractive bronze-red or purple foliage in the fall. The shrub grows to a height of three to six feet. Hobblebush serves a variety of wildlife. Browsers eat its twigs and leaves. Game birds, songbirds, and mammals eat the fruit.

Another common understory plant is

Striped Maple

, an indicator species of the Northern Hardwood forest. It is a deciduous understory tree or large shrub which flourishes in cool, moist woods in the Adirondack Mountains. Striped Maple leaves turn yellow in the fall. These plants can also be found in mixed wood forests. The Striped Maple is an important browse plant for wildlife. Its twigs are browsed by Snowshoe Hare; Red Squirrels and Eastern Chipmunks eat the seeds. Striped Maple is frequently eaten by North American Porcupines. The Striped Maple also provides browse for White-tailed Deer and moose. Striped maple are also very useful to wildlife in that these understory plants help diversify the vertical profile of a forest, creating the dense layers in a woodland that are attractive to many wildlife species for nesting, feeding, and perching.

Wildflowers and Ferns of the Northern Hardwood Forest

The wildflowers and ferns that flourish in the deeply-shaded forest floor of a mature northern hardwood forest are those that are very tolerant of shade. The only sun-loving wildflowers which bloom in a mature hardwood forest are found on the edges of wide trails or in places where a blowdown or other disturbance has created a gap in the tree canopy.

Adirondack Wildflowers: Trout Lily at the Paul Smiths VIC (9 May 2015).

Wildflowers of the Adirondacks: The Trout Lily, like other spring ephemerals, takes advantage of the full sun hitting the forest floor early in the growing season. Trout Lily at the Paul Smith's College VIC (9 May 2015).

Northern hardwood forests are home to a group of spring-blooming wildflowers known as

spring ephemerals

. These are perennial woodland plants that sprout from the ground in deciduous forests in early each spring, then quickly bloom and seed before the canopy trees overhead leaf out. Once the leaves of the deciduous trees above are fully-developed and the forest floor is deep in shade, the foliage of these plants wither away leaving just the roots, rhizomes, and bulbs underground.

Spring ephemerals that bloom in the Adirondack Mountains include Trout Lily, Squirrel Corn, Carolina Spring Beauty, and Dwarf Ginseng. You can also find many of these plants in mixed wood forests, but almost always under deciduous trees. These little plants emerge, bloom, and die back very quickly, sometimes (depending on the weather) in a matter of a few days, so nature lovers seeking to find them need to carefully time their spring wildflower walks.

Adirondack Wildflowers: Purple Trillium at the Paul Smiths VIC (9 May 2015).

Wildflowers of the Adirondacks: Purple Trillium is a shade-tolerant wildflower which blooms in the Northern Hardwood Forest. Purple Trillium at the Paul Smith's College VIC (9 May 2015).

Other

shade-tolerant wildflowers

common in northern hardwood forests in our region include Purple Trillium, Indian Cucumber-root, Jack-in-the-Pulpit, Canada Mayflower, Starflower, and Wild Sarsaparilla. Most bloom in the spring, many in dappled sunlight before the leaves of the maples and beeches above have fully developed. Many of these plants may also be found in mixed wood forests, often in proximity to a group of deciduous trees.

Ferns

– non-flowering, perennial plants that reproduce by spores – are an important component of the forest understory. Together with wildflowers, they form an intermediate layer between the understory and a litter layer of decomposing leaves and wood. Ferns found in the northern hardwood forest include Northern Lady Fern, Interrupted Fern, Hay-scented Fern, Intermediate Woodfern, and New York Fern. Two fern allies – Shining Clubmoss and Tree Clubmoss (or Ground Pine) – are also found in this habitat in abundance.

Wildlife of the Northern Hardwood Forest

Birds of the Adirondacks: Yellow-bellied Sapsuckers favor early-successional deciduous trees for both nesting and feeding. Yellow-bellied Sapsucker. Country Club Lane, Lake Placid (4 May 2015)

Birds

that make their home in the northern hardwood forest of the Adirondack Mountains include both year-round residents (primarily generalists like the Black-capped Chickadees, Common Ravens, and Downy Woodpeckers) and summer residents, such as Ovenbird, Wood Thrush, Red-eyed Vireo, Eastern Wood-Pewee, ,Black-and-white Warbler Black-throated Blue Warbler, Veery, and Scarlet Tanager. Many of these summer migrants rely on the deciduous forest for both feeding and nesting sites. The Scarlet Tanager, for instance, prefers mature deciduous forest during breeding season and often nests in maple or beech. This bird commonly forages on three of the primary deciduous trees of the Northern Hardwood Forest: Sugar Maple, American Beech, and Yellow Birch.

Adirondack Mammals: Gray Fox near Country Club Lane, Lake Placid Gray Fox near Country Club Lane, Lake Placid (5 July 2015).

Mammals of the Adirondacks: Although the Gray Fox can be found in mixed forests and forest-farmland edges, it favors deciduous woodland. Gray Fox near Country Club Lane, Lake Placid (5 July 2015).

Characteristic

mammals

of the Northern Hardwood Forest in the Adirondacks include the Eastern Chipmunk, Eastern Gray Squirrel (along the eastern and southern margins of the mountains), Southern Flying Squirrel, Gray Fox, Porcupine, Black Bear, Eastern Coyote, Striped Skunk, Fisher, Raccoon, Bobcat, and White-tailed Deer. These species rely to varying degrees on deciduous trees as a vital food source. The Yellow Birch, for example, provides browse for White-tailed Deer. Moose, Eastern Cottontail, and Snowshoe Hare also use the plant for food. Red Squirrels cut and store the mature catkins of the birch and eat the seeds. American Beaver and North American Porcupine chew the bark.

Many of the mammal species who live in this habitat, like the Eastern Chipmunk, Gray Fox, and Fisher, can also be found in mixed wood forests. Others, like the White-tailed Deer, can also be found in farmlands and the brushy areas of successional fields.

Adirondack Butterflies: Canadian Tiger Swallowtail at the Paul Smiths VIC (9 June 2012)

Butterflies of the Adirondacks: Caterpillar hosts of the Canadian Tiger Swallowtail include the leaves of birch, aspen and black cherry. Canadian Tiger Swallowtail at the Paul Smith's College VIC (9 June 2012).

Some species of

butterflies and moths

can commonly be found in the northern hardwood forest in the Adirondack Mountains.

Butterflies often seen in this habitat include the Eastern Comma, Spicebush Swallowtail, and Canadian Tiger Swallowtail.
Moth species include the Rosy Maple Moth, Promethea Silkmoth, Polyphemus Moth, and Luna Moth. Deciduous trees provide a host plant for several of these moths, such as the Rosy Maple Moth, preferred host is the maple tree. Caterpillar hosts of the Luna Moth include Paper Birch, while the Polyphemus Moth lays its eggs on a variety of deciduous trees, including birch, maple, and beech.

Amphibians of the Adirondacks: Red Eft at the Paul Smiths VIC (7 June 2012)

Amphibians of the Adirondacks: The Eastern Red-spotted Newt is known as a Red Eft during its terrestrial stage. Red Eft at the Paul Smith's College VIC (7 June 2012)

Amphibians and Reptiles

of the Adirondack hardwood forest include the Eastern Red-spotted Newt, Spotted Salamander, American Toad, and Common Garter Snake. Some are generalists, like the Common Garter Snake, and are found in many terrestrial habitats.

The Eastern Red-spotted Newt only appears in this habitat during its terrestrial stage, when it is known as a Red Eft. These creatures begin life as aquatic larval newts, then transform into brightly-colored Red Efts in their terrestrial stage. Red Efts spend several years on land, then return to water, transforming into aquatic adults. Red Efts are mostly diurnal. Look for them in the leaf litter of the forest floor. The bright orange color warns predators of their toxic skin secretions.

References

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D. Andrew Saunders. Adirondack Mammals (Adirondack Wildlife Program. State University of New York College of Environmental Sciences and Forestry, 1995).

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