Mixed Wood Forests in the Adirondacks

Adirondack Habitats: Mixed forest on the Jenkins Mountain Trail at the Paul Smiths VIC (12 August 2013)
Adirondack Habitats: Mixed wood forest at the Paul Smith's College VIC (12 August 2013).

Mixed Wood Forest represents a transition zone between the forested wetlands on lower elevations and the Northern Hardwood Forest, which occupies the better drained, gentle slopes at a slightly higher elevation. In these in-between environments, conifers such as Red Spruce and Balsam Fir mix with Eastern Hemlock, as well as deciduous trees, including Red Maple, Yellow Birch, and other hardwoods.  

Mixed Wood Forests grow on soil derived from outwash – the sand and gravel deposited by glacial rivers. This soil is rarely fertile enough to support the more demanding northern hardwoods.  The mix of conifers and hardwoods varies with soil fertility and the height of the water table. 

Trees of the Mixed Wood Forest

The dominant species in the Adirondack Mixed Wood Forest include include Red Spruce, Balsam Fir, Eastern Hemlock, Red Maple, and Yellow Birch. The percentage of Red Spruce and Balsam Fir is greatest at lower elevations, where a high water table keeps moisture near the surface. Here Red Spruce grows alongside Eastern Hemlock, Red Maple, Black Cherry, and Yellow Birch. The proportion of Red Maple and Yellow Birch increases on better drained areas. On drier outwash sites, Eastern White Pine and Red Pine, species that tolerate droughty conditions, may appear on drier outwash sites like eskers. 

Trees of the Adirondacks: Red Spruce Red Spruce on the Barnum Brook Trail (28 July 2012)
Trees of the Adirondacks: Red Spruce's four-sided needles are sharp-pointed and prickly, growing all around the twig. The needles exude a fruity scent similar to that of orange rind when crushed.  Red Spruce Red Spruce on the Barnum Brook Trail (28 July 2012).

Red Spruce (Picea rubens) is a key component of the Mixed Wood Forest. It is a medium-sized evergreen conifer that grows on glacial deposits. Red Spruce trees can usually be found with Eastern Hemlock and Balsam Fir. Red Spruce trees also grow with deciduous species, including aspens, birches, maples, and beech species.  Red Spruce does not grow in bogs, which is fortunate because this provides a convenient way to distinguish it from Black Spruce.

Red Spruce is quite vulnerable to damage from acid rain, which leaches calcium out of the needles. This reduces the needles' ability to tolerate freezing temperatures and interferes with the tree's ability to acquire nutrients from the thin Adirondack soils.

Red Spruce plays an important role in the Mixed Wood Forest, providing food and cover for various mammals and birds. Habitats which include Red Spruce are particularly important as winter cover for White-tailed Deer and, to a certain extent, MooseRed Squirrels, mice,and voles eat buds and seeds. Porcupines feed on the bark in winter. Red Spruce is a common tree species in the breeding habitat of a wide variety of birds, including White-throated Sparrows and Red-breasted Nuthatches.

Adirondack Birds: Yellow-rumped Warbler near the first overlook on the Barnum Brook Trail. (17 September 2014)
Birds of the Adirondacks: Yellow-rumped Warblers frequently nest in Balsam Firs or other conifers in Mixed Woods Forests. Yellow-rumped Warbler near the first overlook on the Barnum Brook Trail. (17 September 2014).

Balsam Fir (Abies balsamea), another conifer, is a common understory tree associated with Red Spruce. Balsam Fir is more aggressive in getting established in the wake of a forest disturbance. However, because it is a short-lived species, it eventually loses out to the more longer-lived Red Spruce. The Balsam Fir features dark green aromatic foliage (tipped by attractive lighter green new growth) and a narrow, pointed, spire-like crown. 

The Balsam Fir is moderately important to wildlife. The evergreen foliage of young trees is useful to mammals and game birds for cover, especially in winter. Browsers, particularly White-tailed Deer and Moose, may resort to fir foliage as a large part of their winter menu. The seeds are sought by Red Squirrels, chipmunks, and other rodents. Porcupines feed on the bark. Balsam Fir also provides food and breeding habitat for a number of birds. The winged seeds are eaten from the cones by at least eight species of songbirds (such as crossbills). Yellow-rumped Warblers, Magnolia Warblers, Veery, and Rose-breasted Grosbeaks often choose this species as a nest site.

Trees of the Adirondacks: Eastern Hemlock on the Barnum Brook Trail (21 July 2012)
Trees of the Adirondacks: The Eastern Hemlock has attractive blue-green needles and a loose, irregular, feathery silhouette. Eastern Hemlock on the Barnum Brook Trail (21 July 2012).

Eastern Hemlock (Tsuga canadensis) – is the most shade-tolerant conifer in the East. It can grow in well-drained to poorly-drained till or outwash. It is seen in both the Northern Hardwood Forest and the Mixed Wood Forest, often accompanied by Yellow Birch, Red Spruce, and Balsam Fir.

Eastern Hemlock provides valuable food and winter shelter for wildlife. Many species of wildlife benefit from the excellent habitat that a dense stand of hemlock provides. Hemlock bark and twigs also provide winter nutrition for porcupines, and the seeds provide food for Red Squirrels, mice, voles, and other rodents. Eastern Hemlocks are also important in creating a habitat for birds. This tree is sometimes chosen as a nest site by Yellow-rumped Warblers and Blackburnian Warblers. Other birds rely on the small, winged seeds from the cones for food.

Adirondack Trees: Red Maple flowers from the Jenkins Mountain Trail overlook (5 May 2015).
Trees of the Adirondacks: The small pinkish to red flowers of the Red Maple add a rosy glow to mountain landscapes. Red Maple flowers from the Jenkins Mountain Trail overlook (5 May 2015).

Red Maple (Acer rubrum) is a key deciduous species in the Mixed Wood Forest, thriving wherever Sugar Maple cannot dominate. It is not terribly fussy about soil and drainage and does well even in poorly-drained, shallow, or very sandy soils. Moderately shade-tolerant, it will grow almost anywhere except under dense shade. It commonly associates with, and competes with, the Yellow Birch.

The Red Maple is one of the first trees to flower in the spring, generally several weeks before the leaves appear. The flowers are small, with slender stalks, pink to red. This species is one of the early harbingers of autumn, as it turns color well in advance of other eastern deciduous trees, especially when it is located in wet sites. The fiery colors of fall are typically a brilliant red.

Red Maple leaves, twig, bark, and fruits provide a food source for numerous mammals, birds, and insects. However, Red Maple leaves are extremely toxic to horses and cattle. The species is not preferred by deer as a browse source, so in areas with heavy deer pressure, this species is over-abundant in forest regeneration. The Red Maple is a larval host for the Rosy Maple Moth. Red Squirrels use the cavities of older trees as nesting habitat. A number of birds build nests in Red Maples, including American RedstartsBlack-backed Woodpeckers, and Downy Woodpeckers

Trees of the Adirondacks: Yellow Birch on the Barnum Brook Trail (10 May 2014).
Trees of the Adirondacks: The distinctive, golden bark of Yellow Birch peels horizontally into thin,filmy strips. Yellow Birch on the Barnum Brook Trail (10 May 2014).

The Yellow Birch is the third dominant of the northern hardwoods. It is somewhat less shade-tolerant than Sugar Maple and American Beech, but is able to thrive on more diverse sites, even on hummocks around swamps and other poorly-drained sites where Sugar Maple and American Beech do not occur. The Yellow Birch is common in both Mixed Wood Forests and Northern Hardwood Forests.

Yellow Birch trees are an important plant for wildlife, providing a favorite 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 and eat the seeds. American Beaver and North American Porcupine chew the bark. Yellow Birch trees are also an important food source for many birds, including  Pileated WoodpeckersFox SparrowsBlack-capped ChickadeesPine SiskinCommon Redpoll, and Ruffed Grouse.  This tree also provides a nesting site for Ruby-throated Hummingbirds, Broad-winged Hawks, Red-shouldered Hawks, and Boreal Chickadees.

Shrubs of the Mixed Wood Forest

The understory of the Mixed Wood Forests consists of shade-tolerant shrubs, smaller tree species, and the saplings of canopy plants. Shrubs associated with the Mixed Wood Forest include Hobblebush, Red Elderberry, Mapleleaf Viburnum, Alternate-leaf Dogwood, American Fly-honeysuckle, and Low Bush Blueberry.

Adirondack Shrubs: Hobblebush at the Paul Smiths VIC (8 May 2013).
Shrubs of the Adirondacks: The large showy flowers along the edge of the Hobblebush cluster are sterile, while the small inner flowers have both male and female parts. Hobblebush at the Paul Smith's College VIC (8 May 2013). 

Probably the most abundant understory element seen in the shade of a mature Mixed Wood Forest is the ubiquitous Hobblebush, which also occurs commonly in Northern Hardwood Forests. The Hobblebush (Viburnum lantanoides) is a native deciduous shrub which can flourish in a variety of habitats, including rich, moist woods, by stream banks, and in swamps. Its abundance in Adirondack forests is because it it so shade and acid tolerant.

Hobblebush serves a variety of wildlife. The berries are a food source for both game birds and songbirds, such as the Cedar Waxwing, Pine Grossbeak, Brown Thrasher, and Ruffed Grouse. White-tailed Deer and Moose feed on its buds and branches. Hobblebush flowers provide nectar for the Spring Azure butterfly. The shrub's rooting habit improves soil stability on steep terrain and provides cover for many small animals and ground birds.

Adirondack Wildflowers: Canada Mayflower at the Paul Smiths VIC (30 May 2015).
Wildflowers of the Adirondacks: Canada Mayflower is abundant in all types of dry to wet woods, even in dense shade. Canada Mayflower at the Paul Smith's College VIC (30 May 2015).

Wildflowers and Ferns of the Mixed Wood Forest

A wide variety of shade-loving wildflowers abounds on the forest floor of a mature Mixed Wood Forest.

Adirondack Wildflowers: Indian Cucumber-root at the Paul Smiths VIC (14 September 2013).
Wildflowers of the Adirondacks: Indian Cucumber-root blooms in late May and assumes its vivid fall colors in September. Indian Cucumber-root at the Paul Smith's College VIC (14 September 2013).

As fall and cooler temperatures arrive, most of the shade-loving wildflowers that grow in the Mixed Wood Forest have stopped blooming. To compensate, a number of them add to the fall palette with brilliant foliage or colorful berries.

  • Bunchberry foliage turns an eye-catching wine red, with splashes of dark purple.
  • The foliage of the two-tiered Indian Cucumber-root turns yellow, with the smaller whorl of three leaves near the top splotched with a bright red center.
  • Wild Sarsaparilla foliage turns orange, yellow, or deep red, with accented veins and margins.
  • The foliage of White Baneberry turns an attractive yellowish green, with the veins and margins outlined in darker green.

Many of the Ferns and Fern Allies found in the Northern Hardwood Forest in the Adirondacks also grow in abundance in the Mixed Wood Forest.

  • The list includes evergreen ferns such as Spinulose Woodfern (abundant in hardwoods and mixed forest), Christmas Fern (which almost always grows under Sugar Maple), and Intermediate Woodfern (which flourishes in hemlock-hardwood forests).
  • Deciduous ferns found in the Mixed Wood Forest include Hay-scented Fern (usually growing in large groves in sunny forest openings), Lady Fern (which grows in both northern hardwood and mixed wood forest), Maidenhair Fern (usually occurring under Sugar Maple), and New York Fern (which usually occurs under northern hardwoods).
  • Three fern allies – Shining Clubmoss, Bristly Clubmoss, and Tree Clubmoss (also called Princess Pine or Ground Pine) – are also found in this habitat in abundance. Ground Cedar, although less common, can also be found here.

Wildlife of the Mixed Wood Forest

Adirondack Birds: Pine Siskin near Country Club Lane, Lake Placid (26 April 2016).
Birds of the Adirondacks: A year-round resident of the Adirondack Park, the Pine Siskin nests primarily in loose colonies in relatively open conifer or coniferous-deciduous forests. Pine Siskin near Country Club Lane, Lake Placid (26 April 2016).

A wide variety of birds are seen and heard in this habitat, including both permanent residents and summer migrants. Many birds which are commonly associated with either hardwood or coniferous forests are equally at home in a mixed wood habitat.

Most of the year-round resident birds that can be found in mixed woodland are species which can flourish in other habitats as well. The list includes the Black-capped Chickadee, Brown Creeper, Common Raven, Golden-crowned Kinglet, Hairy Woodpecker, Pileated Woodpecker, Northern Saw-whet Owl, Purple Finch, Pine Siskin, Red-breasted Nuthatch, Ruffed Grouse, and Blue Jay. For several other birds, like the Barred Owl, the mixed wood habitat is their preferred breeding habitat.

Adirondack Birds: Hermit Thrush at the Paul Smiths VIC (27 July 2015).
Birds of the Adirondacks: The lovely, melancholy song of the Hermit Thrush can be heard in both Northern Hardwood Forest and Mixed Wood Forests in the Adirondacks. Hermit Thrush at the Paul Smith's College VIC (27 July 2015).

Many of the Adirondack Park's summer birds make their homes in mixed woodlands, wintering further south and returning to the Adirondacks in the spring. Summer resident birds commonly seen in this habitat include Cedar Waxwings, Chipping Sparrows, Hermit Thrush, Northern Flickers, Red-eyed Vireos, Ruby-crowned Kinglets, Ruby-throated Hummingbirds, Song Sparrows, White-breasted Nuthatches, White-throated Sparrows, and Winter Wrens.

Mixed woodlands also provide a major breeding habitat for a wide variety of warblers, like the Black-throated Blue Warbler, Black-throated Green Warbler, Blackburnian Warbler, Canada Warbler, Nashville Warbler, Northern Parula, Ovenbird, Pine Warbler, and Yellow-rumped Warbler.

Adirondack Mammals: Red Squirrel on the Logger's Loop Trail at the Paul Smiths VIC (29 May 2014).
Mammals of the Adirondacks: Although Red Squirrels may reside in deciduous forests, they are most at home in mixed and coniferous forests. Red Squirrel on the Logger's Loop Trail at the Paul Smith's College VIC (29 May 2014).

Mammals of the Mixed Wood Forest in the Adirondacks include the Eastern Coyote, Red Fox, Bobcat, Fisher, Short-tailed Weasel, Long-tailed Weasel, American Marten, Ermine, Raccoon, Black Bear, Eastern Chipmunk, Gray Squirrel, Northern Flying Squirrel, Southern Flying Squirrel, and White-tailed Deer. Many can also be found on other habitats. These species rely to varying degrees for food and shelter on both deciduous and coniferous trees, or the wildlife that dwells near them. Many of these mammals (such as the Black Beer, Red Fox, and Raccoon) are omnivores, consuming a wide variety of food items. Others, like the Bobcat, Long-tailed Weasel, and Ermine, are carnivores. Beavers and Porcupines are herbivores.

The distribution of each species is linked in part to the availability of its major food source. The Eastern Coyote, for instance, occupies virtually any habitat, but seems to prefer areas with a combination of brushy areas, woodlots, and open country. Although coyotes are opportunistic carnivores, consuming many species of small mammals, White-tailed Deer make up an important winter food source for coyotes living in the Adirondacks. For that reason, coyotes (which reportedly hunt deer in small packs, like wolves) appear to be more abundant in places where deer are common, such as the lower elevation areas of the Adirondack Park.

Adirondack Butterflies:  White Admiral near the Heron Marsh Trail at the Paul Smiths VIC (25 June 2016).
Butterflies of the Adirondacks: The White Admiral is common in mixed and deciduous forests, forest edges, and near streams. White Admiral near the Heron Marsh Trail at the Paul Smith's College VIC (25 June 2016).

Some species of butterflies and moths can be found in the Mixed Wood Forest in the Adirondack Mountains.

Look for these insects along the edges or trails or in forest clearings, since many of them use the sun-loving wildflowers that grow in these spaces as host plants or as sources of nectar as adults.

Frogs of the Adirondacks: Spring Peeper near the Heron Marsh Trail at the Paul Smiths VIC (1 August 2015)
Adirondack Frogs: The tiny Spring Peeper, well-known for the shrill peeping sounds which herald spring, prefers wooded areas near permanent or temporary ponds or marshes. Spring Peeper near the Heron Marsh Trail at the Paul Smith's College VIC (1 August 2015)

Amphibians and Reptiles that dwell in mixed woodlands include the Four-toed Salamander, Two-lined Salamander, Eastern Red-spotted Newt, American Toad, Spring Peeper, Gray Tree Frog, Ringneck Snake, Red-bellied Snake, and Common Garter Snake. Some are generalists, like the Common Garter Snake and Gray Tree Frog, and are found in many terrestrial habitats.

One of the most interesting of the 19 amphibians found in the Adirondack Park is the Gray Tree Frog (Hyla versicolor), a small arboreal frog native to much of the eastern United States and southeastern Canada. The Gray Tree Frog is not often seen, because it spends much of its time residing on branches and twigs above eye level, rather than on the forest floor. Moreover, this creature is equipped with a very effective protective camouflage. Normally gray or grayish green, the Gray Tree Frog can vary its color, depending on its background – a strategy that makes it so inconspicuous that it is likely to be overlooked by passing trail walkers. The Gray Tree Frog navigates through the branches using toes equipped with special suction-cup ends that allow it to attach itself to tree surfaces. 


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