My hemlock



Every culture has a myth about the “tree of life” except the western one unless we include the Christmas tree which today is often made of plastic. As we approach the holiday season I am sickened by the thought of more live trees being cut down, only to be thrown out the door as soon as the presents are opened. I see the tree as a kind of backdrop for the human drama. The Christmas tree seems to be a symbol for excessive consumption for most.

Nature no longer structures our collective reality in any meaningful way, and trees, if they are noticed at all, are viewed as a kind of indoor or outdoor wallpaper.

It is my intent in this article to bring one tree to life…

Eastern Hemlocks are one of my favorite woodland trees and have been since I was a child. During the years my brother was at Harvard I spent a lot of time at that institution because my brother raced and trained in the Harvard Forest. Davey was an internationally known runner who held the steeplechase record until about 20 years ago. Not surprisingly, we always ended our time in Petersham relaxing and talking under the hemlocks.


Every year in the late fall after all the leaves of deciduous trees have fallen, the deep green needles and elegant curved shapes of hemlocks stand out like sentries bowing over my brook. Graceful evergreen boughs cascade over the water, creating a canopy that stabilizes temperatures all year long. The first snows bow the young ones low, but they never break. In my small hemlock forest that borders both sides of the stream, it is always cool and dark. Plant growth is sparse in the places where hemlocks overlap one another. In places where hemlock forests have been left to re-wild themselves, many ground covers and other interesting plants can be found growing near hemlocks and their companions, oak and beech, including some rare species.

Animals thrive in hemlock territory; the red eft is one that appears regularly after a rain. Deer browse and seek cover under hemlock boughs. Red squirrels and mice feast on hemlock seeds. Hares like the foliage. Bears once took cover under their boughs. Many insects inhabit the rich humus under hemlocks, and in the branches of these trees, songbirds flourish. Blue-throated green warblers, Blackburnian warblers, Acadian flycatchers, hermit thrushes, winter wrens, nuthatches are just a few examples. The Blackburnian warbler nests nowhere else. Most of the warblers that I heard this summer were hiding in hemlocks! Ruffed grouse, barred owls, and Saw-whet owls like to roost in hemlocks branches. Hawks like them too. Brook trout need hemlocks to keep the water pure and cool.

Hemlocks are also one of the trees that have been spared by logging up until recently (now we take them to be ground up for pulp and garden mulch – spreading the wooly adelgid in the process of mulching gardens). This means that in most forests, hemlocks may be older than other trees because their wood was not deemed valuable. All forests have been cut at least two or three times, usually sustainably until about 40 years ago when what I call ‘the industrial logging machine’ took over stripping forests, uprooting tree trunks, and ruining the soil.

Hemlocks have both male and female reproductive structures on each tree and in the fall, small cones adorn the tips of flat – needled branches. The tree’s ability to seed itself so close to a parent – within a hundred feet – allows the seedlings to be nourished through roots from the mother tree. Hemlock roots are attached to a complex underground mycelial network that stretches across the forest floor. Wherever hemlocks survive, each is a living museum of the ecology of the woods in that particular region. Because these trees thrive in the lowlands, hemlock pollen can also be studied because it has been preserved for millennia in the sediments of lakes, bogs, swamps and wetlands where these trees have grown.

Eastern Hemlocks returned after the last glacial period, arriving in New England about 10,000 years ago from the south. They ‘migrated’ north about 900 miles in 5000 years, keeping up with changing climate conditions. Their range extends from Nova Scotia to Michigan. Today, of course with climatic change upon us, these trees are under stresses they haven’t been before.

Curiously, hemlocks and the chestnut tree had a reciprocal relationship. There is no evidence of hemlock disturbance by Native peoples prior to the European invasion. For the last 5000 years hemlocks have been interspersed with white pine, beech, oak, maple and birch, cedar and spruce. Beech and oak are also very shade tolerant trees.

In addition to being shade tolerant, hemlocks are also the most patient of trees. When a space in the canopy opens, even a tree that is already 75 – 100 years old will shoot up to the sky, branching its ladders to reach the sun. A pencil thin hemlock can be 100 years old! Tiny flat forest green needles create and layer their own canopy in a patterned way that allows every stream of light to be maximized by the tree – an incredible strategy to make the most of low light.

Hemlocks can also photosynthesize at very low temperatures – just above freezing. In the spring before leaf out the hemlocks absorb high light, creating optimal conditions for growth. Besides pine, beech and oak, in untrammeled forested areas, hemlocks are also peppered with mountain laurel, hobblebush, and witch hazel, understory plants that can also tolerate lower light. A small plant called twisted stalk can also be found here. Indian pipes are a common sight in summer. Partridgeberry and wintergreen too.

When adult trees die, their nutrients slowly seep into the ground because this tree decays very slowly, nourishing the rest of the trees and plants of the forest. Mushrooms, fruiting bodies of fungi that belong the complex underground highway of the mycelial network, appear at their feet. There are 20,000 fruiting fungi in all. Hemlock varnished shelf mushrooms are my favorites. Morels and Chanterelles are editable mushrooms that I have found growing under hemlocks. Amanitas, giant Lactarius (some reach the size of dinner plates) and blushing Russulas are also common around here, as are Boletes – Coral mushrooms and Indian pipes (the latter is not a mushroom) are also familiar sights. Various Cortinaruis species abound…. Hemlocks seem to be a hotbed for so many species of fruiting fungi.
Many have a mycorrhizal relationship with hemlocks. Recall that mycorrhizal mushrooms are mutualistic fungi that form a symbiotic relationship with plants and trees. In the west a list of over 100 mycorrhizal fungi were associated with hemlocks. Mycorrhizal mushrooms can extend a plant’s root system up to 1000 times, playing a critical role in forest ecosystems. The presence of so many plants and mushrooms under or around forests free of recent logging was what drew me to these magnificent trees in the first place aside from their size and beauty. Hemlocks obviously impact the ecosystem around them in profound ways.

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