Northern Hardwood Forest

The Mountain of Oaks, Mt. Wachusett

A common stereotype that surrounds the concept of a “mountain” involves either a summit populated with coniferous (evergreen) trees, or a treeless summit surrounded by coniferous forests below the treeline. Indeed this assumption holds mostly true for many mountains in New England, including the famous Mt. Washington, Mt. Cardigan, Mt. Monadnock, and Pack Monadnock. A strange phenomenon exists on the nearby Mt. Wachusett, however. Instead of a summit of conifers, Red Oak dominates the available soil.

Scrubby oaks, limited in growth by thin mountaintop soils and rocky terrain, dominate on the summit of Mt. Wachusett

Why might this be the case? Despite being only about 30 miles south of Pack Monadnock, and only 200 feet lower in elevation, the ecological communities of Mt. Wachusett’s summit differ drastically in character. Pack Monadnock showcases a beautiful array of spruce mixed with northern hardwood species mosaics (beeches, birches, and maples) on and around its summit. The very top of Mt. Wachusett, on the other hand, is a scrubby patch of red oaks surrounding the bare summit. It’s beautiful and fascinating in its own way, but a bit confusing.

That’s not to say Mt. Wachusett is completely devoid of northern hardwoods or spruce. In the ideal growing conditions on the northern slopes, many of these species tend to dominate, particularly the yellow birch. However, old growth oak is still a mainstay throughout these forests. Red spruce is limited to a narrow band on the northern slope just below the summit, but does not breech the ring of scrub oaks at the top.

Old growth yellow spruce, showing the cracks of aging, grows along the Old Indian Trail on Mt. Wachusett

There could be a few reasons for this interesting phenomenon. While much of the research on Mt. Wachusett’s ecology has involved documenting its old growth forest below the summit, there are a few historical and environmental clues that we can use to try and explain the oaks without doing scientific research ourselves! The further south we go in New England, generally the more frequent fire regimes become. While cold ravines and slopes are protected from fires for long periods of time due to their moisture retention, the exposed summit of Wachusett may not retain as much water, allowing fire regimes to historically reign more frequently in this area. Oaks are a species that tend to thrive in areas that are a little drier, and see a little bit more fire, than red spruce and northern hardwoods. In fact, red spruce is particularly susceptible to fire damage.

Another possible explanation is the more recent active disturbances on the summit, which included various recreational structures over the last century. Trees were at different points cleared out to make way for roads and buildings, but the areas of disturbance have evolved over time, potentially allowing some forest to grow back. Red oak is considered to be an early to mid successional species, while red spruce is a late successional species. While climate change may drive the spruce out of this area entirely at some point, without that factor we could have seen more spruce begin to grow in the shadow of these oaks over time, perhaps replacing some of them in the canopy eventually. These are just theories of my own imagination, though, so perhaps scientists will seek to definitively explore this question at some point.

Mt. Wachusett poses this question to us laymen, but it has been studied for almost two decades now thanks to the discovery of four distinct areas of old growth on different slopes of the mountain. This was a particularly incredible find for the area because there were virtually no known old growth areas east of the Connecticut Valley in Massachusetts of this forest type. Many of the other known old growth areas lie in swampy or sandy unfarmable land down towards Cape Cod and Plymouth, and these forests have a much different ecological composition than areas further from the shore.

Wachusett’s old growth areas showcase distinct characteristics depending on their location on the mountain. On the Old Indian Trail, which lies on a north facing slope, we tend to see a transitional hardwood forest, consisting of the aforementioned yellow birches of varying size and age, as well as extremely mature red oak trees, some of which have exceeded their expected lifespan. The harshness of the terrain and frequency of wind events have actually protected these strong old trees that have stood the test of time, knocking out weaker competitors and leaving an open canopy for them to flourish.

Old growth red oak shows crown damage and diversion over time due to the harsh conditions on the mountain. This tree was strong enough to survive generations of storms and wind events

There are four total distinctly studied old growth areas of the mountain. I have not yet visited all of them in person, but in three we can find similar mixed stands of yellow birch, American beech, red oak, and red maple, though the predominance of each type varies. On the southwestern portion of the mountain, we can also find a stand dominated by old growth hemlock.

For easy access to the most well known old growth area of the park, you will need to pay a $5 fee to enter the road that leads to the parking lot across from the Old Indian Trail. You can also start hiking from the base of the mountain closer to the ski resort village. When I went in the summer, the environment was fairly hot and humid with a decent number of mosquitoes, so bug spray is recommended during peak summer. Winter hikes may require microspikes and/or snowshoes depending on recent snowfall amounts. Like most hikes in Massachusetts, spring and fall are the best times for avoiding the most extreme of conditions.

america, mid atlantic

Discovering Forest Mosaics in Upstate New York

Having spent most of the past several years in eastern Massachusetts, I have not had much opportunity to really dive into the minute differences between the forest ecosystems of the eastern United States. I had heard of a few unique locations that differed from the oak and pine-dominated lowlands of my home region, such as the temperate rainforests of the southern Appalachians, as well as the northern hardwood forests of the northernmost regions of New England. I didn’t stop to think much, however, of how these northerly latitude forests adjust as we move westward into New York state past the remote Adirondack mountains and beyond into the Midwest. Subconsciously, I believed that these forests would resemble the oak-pine dominated areas of Massachusetts that extend south into Rhode Island, Connecticut, and beyond.

With this line of thinking I recently visited upstate New York, in the northernmost region just south of the Canadian border, about an hour’s drive south of Ottawa and near the St. Lawrence River. What struck me most as I was driving westward away from the coast of Massachusetts was the seemingly slow reduction of oaks in the canopy. They almost completely disappeared as I reached the Berkshires, the famous sub-range of the Appalachians in western Massachusetts. As I continued into New York, for the most part I saw very different tree combinations, known as northern hardwoods. The occasional dominance of oak pine forests seemed somewhat tied to altitude, latitude, and local soil conditions.

Northern hardwood forests are very beautiful and tend to have a lighter, airier feeling than both the oak-pine forests in the south and the spruce-fir forests of the north. They tend to be dominated by sugar maples, american beeches, and yellow birch trees. We also see hemlock conifers dominating in certain wetland areas that they are adapted to. At higher elevations, colder regions and more northerly latitudes, these northern hardwood forests start mixing with more spruce-fir forests, while in warmer, drier locations, they start to mix in with the oak-pines, as they do in eastern Massachusetts. In some areas, particularly Maine and other parts of northern New England, paper birch can also be a dominant canopy tree in early succession forests, or forests that have recently been clear cut, blown down, or damaged in some other way.

Despite a comparative dearth of oaks in comparison to eastern Massachusetts, they are not completely missing from the canopy near the Lawrence River. Where oaks have been able to dominate have sometimes been human curated or influenced, but oaks can still be found often as understory shrubs in northern hardwood forest settings, as well as fully dominant on soils that are thinner, rockier, or clay-based (which is a more common soil type as we move closer to the St. Lawrence watershed). In Massachusetts, their dominance is presumed to be influenced by prior fire regimes and clearing of forests for farmland, which has changed the forest composition significantly. Fires are believed to help stimulate acorn growth and clear out species that compete with oaks, though red oaks do slightly better in wetter environments than other varieties. Southern New England still sees significantly fewer fires, however, than ecosystems in the westerns half of the country.

On a short hike down to a view of Cedar Lake, we found these tree dominance trends in full effect. Beech trees were plentiful, but often suffering from beech bark disease, a fairly common ailment to see on an American Beech. Yellow birch appeared to dominate on disturbed sites, such as over stumps and logs of old trees, with occasional white birches making their appearance on the edge of the lake, where they could capture more sun rays. Sugar maples seemed the predominant maple in these forests, which contrasts starkly with the red maple dominance in Massachusetts and further into the south (we did see a few in the understory). I don’t even recall encountering the invasive Norway Maple, which is easily mistaken for sugar maple and very common in eastern Canada and New England. The prevalence of these trees up north supports a strong maple syrup industry that likely isn’t sustainable in southern New England. Red oak was found in the understory, but rarely as a dominant member of the canopy. However, research into other trails in this area has suggested oak and white pine dominance on the rocky ledges above the lake, where the northern hardwood species may struggle to grow.

At the time we went in August, the trail was very overgrown, buggy, hot, and humid. The trails here are also very poorly marked, so it’s easy to take an unintended route down to the lake, but it was easy to see the large body of water through the trees which helped with navigation to a viewing spot. The route down to the lake was steep and muddy, and apparently is meant to function as a canoe launch, though it looks incredibly difficult to get a canoe down the steep, rocky and muddy hill! The area has a history of logging, farming, and fires started by humans, so most of it likely doesn’t represent true old growth forest, but the area we explored seemed to be in a mid successional stage of forest development. While much of the trail’s state suggested a lack of frequent maintenance and lack of heavy usage, going slightly off the beaten path to explore such areas provides us nature enthusiasts the unique opportunity to explore these pristine northern hardwood forests in an area where they face fewer active disturbances.