Trees of the Adirondack Park: Eastern Hemlock at the Paul Smiths VIC (13 October 2013)

Trees of the Adirondacks:
Eastern Hemlock (Tsuga canadensis)

Trees of the Adirondacks: Eastern Hemlock needles are 1/2 inch in length and flattened. Eastern Hemlock on the Barnum Brook Trail (28 July 2012) Trees of the Adirondacks: Eastern Hemlock needles are 1/2 inch in length and flat. Eastern Hemlock on the Barnum Brook Trail (28 July 2012)

The Eastern Hemlock (Tsuga canadensis) is a medium-sized evergreen tree that flourishes in moist soil in the Adirondacks. This tree is also known as the Canada Hemlock or Hemlock Spruce. It is a member of the pine family. It is the only hemlock native to the Adirondack Mountains. The common name "hemlock" was given because the crushed foliage smells a little like that of the poisonous herb hemlock, which is native to Europe. The Eastern Hemlock is a slow-growing, long-lived tree which may take 250 to 300 years to reach maturity.

The Eastern Hemlock is under severe pressure from the Hemlock Woolly Adelgid, an insect pest native to Asia and accidentally introduced to the US. This pest, which leads to decline and mortality within four to ten years, has thrived along the East coast, damaging hemlock forests from Maine to Georgia. Infestations of this pest have been found in 25 counties of New York State, especially in the Hudson Valley and the Finger Lakes. The insect has not yet spread to the Adirondacks, in part because the main barrier to spread is cold temperatures. There is concern that climate change may help accelerate the spread of the insect, leading to extensive loss of hemlock forests, which would in turn have far-reaching effects on the wildlife species that thrive in the microclimates created by this tree.

Trees of the Adirondacks: Eastern Hemlock cones are small and hang down from the end of the twig.  Eastern Hemlock on the Barnum Brook Trail (21 July 2012)
Eastern Hemlock trees have cones that are much shorter than other conifers growing in the Adirondacks. Eastern Hemlock on the Barnum Brook Trail (21 July 2012)

Identification of the Eastern Hemlock: The Eastern Hemlock has a loose, irregular, feathery silhouette, with fine, lacy twigs whose tips tend to droop gracefully. This tree has short, flat, blunt, flexible needles, about 1/2 inch long. The needles are rounded at the tip, dark green above and pale silvery below. The needles have rows of tiny teeth on the margins and appear to grow in flat sprays on the lower limbs of trees. The cones of the Eastern Hemlock are very small (about 3/4 inch long) and hang down from the end of the twig. They persist after shedding their seeds in the fall.

Eastern Hemlock bark is thick and rigid. The root system of this species is shallow, making the tree vulnerable to ground fires, drought, and wind. The tree begins to flower at about age fifteen. Male flowers, which appear from April to early June, depending on the locality, are yellow.

Keys to identifying the Eastern Hemlock and differentiating it from other coniferous trees include its needles, bark, and habitat.

Differentiating Eastern Hemlock from Balsam Fir is somewhat trickier.

Trees of the Adirondacks: The bark of the Eastern Hemlock is brown, thick, and deeply furrowed. Eastern Hemlock on the Barnum Brook Trail (21 July 2012). 
The bark of the Eastern Hemlock is brown, thick, and deeply furrowed. Eastern Hemlock on the Barnum Brook Trail (21 July 2012).

Uses of the Eastern Hemlock: The Eastern Hemlock was used by many native American tribes to treat a variety of ailments, including rheumatism, arthritis, colds, coughs, fever, skin conditions, stiff joints, soreness, and scurvy. Native Americans also used the bark to make dyes and the cambium as the base for breads and soups or mixed it with dried fruit and animal fat for pemmican. Natives and white settlers also made tea from hemlock leaves, which have a high vitamin C content. The plant is still sometimes used in modern herbalism, where it is valued for its astringent and antiseptic properties.

At present, the Eastern Hemlock has more limited commercial uses than some other conifers in the region. The characteristics of hemlock wood limit its use to relatively low-grade products, such as structural lumber, pulpwood, and pallets. Although the bark was once a commercial source of tannin, used in the production of leather, synthetic products are now used in leather production. Hemlock bark is still in demand today, but for landscaping mulch. The Eastern Hemlock makes a poor Christmas tree, since its needles fall upon drying. Its value as firewood is limited by the fact that the wood throws sparks. One use that the Eastern hemlock has retained is as an ornamental. The tree can be used as a specimen, screen, or group planting, and can be sheared over time into a formal evergreen hedge,

Birds of the Adirondacks: Male Blackburnian Warbler near the VIC parking lot (20 May 2014)
Blackburnian Warblers are frequently seen foraging on deciduous trees, but prefer to nest in hemlocks. Blackburnian Warbler near the VIC Parking lot (20 May 2014)

Wildlife Value of the Eastern Hemlock: Eastern Hemlock provides valuable wildlife food and winter shelter. Many species of wildlife benefit from the excellent habitat that a dense stand of hemlock provides. The dense, low branches of young trees provide winter cover for Ruffed Grouse, Wild Turkey, and other wildlife. For example, White-tailed Deer, which have trouble navigating in snow above twenty inches in depth, may yard up in hemlock groves during periods of heavy snow cover. They may also consume the foliage and twigs of hemlock as high as they can reach. 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 species is sometimes chosen as a nest site by Yellow-rumped Warblers. White-winged Crossbills feed on the small, winged seeds from the cones, as do Black-capped Chickadees, Dark-eyed Juncos, Red Crossbills, American Goldfinch, Evening Grosbeaks, and Pine Siskins. The Eastern Hemlock is a common tree species in the breeding habitat of a variety of birds, including:

Blackburnian Warbler Wood Thrush
Northern Parula Black-throated Green Warbler
White-throated Sparrow Golden-crowned Kinglet
Red Crossbill Red-breasted Nuthatch

Distribution of the Eastern Hemlock: This species  is found in the northeastern part of the US, commonly associated with eastern hardwoods. In Canada, it grows in south-central Ontario, extreme southern Quebec, through New Brunswick, and all of Nova Scotia. Within the United States, Eastern Hemlock occurs throughout New England, the mid-Atlantic states (including most counties in New York State), and the Lake States. The Eastern Hemlock's range extends south in the Appalachian Mountains to northern Georgia and Alabama and west from the mountains into Indiana, western Ohio, and western Kentucky. 

Eastern Hemlock trees are found in boreal forests, mixed conifer/hardwood forests, and northern swamp forests. In the northern hardwood forest, Eastern Hemlock is found on a wide variety of sites, including low rolling hills and glacial ridges.

The water of Barnum Brook is a brown tea color, reflecting tannins from nearby hemlocks. Barnum Brook from the bridge on the Barnum Brook Trail (27 September 2011). 
The water of Barnum Brook is a brown tea color, reflecting tannins from nearby hemlocks. Barnum Brook from the bridge on the Barnum Brook Trail (27 September 2011).

Eastern Hemlock at the Paul Smiths VIC: Eastern Hemlocks, in contrast to Black Spruce and Tamaracks, do not grow in the middle of bogs or marshes. However, they do like moist areas, so look for them in somewhat swampy areas or near the banks of brooks. They can usually be found in mixed stands, with other conifers and hardwoods that are tolerant of moist soils.

The most convenient place to observe the Eastern Hemlock at the VIC is on the Barnum Brook Trail. This species is one of the eleven tree species marked with signage along this trail. If you take the left hand fork after passing through the gazebo and walk in a clockwise direction, you will find the Eastern Hemlock just before you cross the bridge over Barnum Brook, about half a mile from the gazebo. The tree is located on the left-hand side of the trail, across from the Paper Birch, providing a convenient way of identifying the preferred habitat of these trees. The water of Barnum Brook is a characteristic brown tea color – the result of tannins leaching out of decomposing conifer needles.



References

Trees of the Adirondack Mountains



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