A "Demonstration Forest" in the making — hunters welcome
In time this will become a Northern Hardwood forest and, if there is no destruction by future generations, perhaps a demonstration example of old-growth forest.
On July 9th the Thetford Conservation Commission enjoyed a tour of a forested parcel in town that is the homestead and probably lifelong project of Donn Downey, a consulting forester who manages public and private land across the Upper Valley. In addition to forestry credentials, Donn has a master’s degree in conservation biology and is endorsed by the National Audubon Society for bird-friendly forest management.
At the start Donn acknowledged the influence of the Biltmore Forest School in Asheville, North Carolina. The school grew from the work of Carl Schenk who came from Germany to manage the forests on George Vanderbilt’s vast land holdings. Schenk introduced science-based forest management and practical techniques and in 1896 established the Biltmore Forest School, the first US school devoted to the subject. At Biltmore there is a demonstration forest with educational kiosks comparing the forest as seen today with how it looked 70 or more years ago. In Donn's opinion there is a need for something like that a bit closer to home.
Donn's tour showcased the forestry work he has done over the last 10-11 years. Like all places, this land has a history. In the early to mid 1800s, an estimated 80% of Vermont's forests were cut down to make way for what swelled to 1.7 million Merino sheep raised for their prized wool. As wool became less profitable, farms switched over to dairy. Many farms, especially hill farms, were subsequently abandoned in the early 1900s as young people left farming for better opportunities.
Even after the ravages of mass deforestation, trees sprang up on the abandoned farms, but they were not representative of the original forest. Because trees started growing at the time point of farm abandonment, they were basically all the same age and often unnaturally rich in white pine. Moreover, as the land came into new ownership, the best of the trees in this re-grown forest were logged again.
This was more or less the picture that Donn inherited. Pointing to a large gnarled ash tree, he explained that, unlike all the “good” trees, this tree had not been harvested by previous owners due to its imperfections. It had no value as a timber tree. A desirable timber tree is straight, with a significant length between the stump and the first limb.
Elsewhere the recently logged areas had become overgrown predominantly with beech. This is not for want of seeds from other tree species. It is the result of an overabundance of deer. Beech is the least favorite deer browse; they much prefer maple, ash, oak, and other hardwoods. Unfortunately in Vermont the deer herd is managed "according to the ability of the forest to support them" and little sensitivity to the myriad other species that require a forest of diverse tree species to thrive. An average deer eats over 4,000 tree seedling tips in one day. Even at 12-18 deer per square mile — the "preferred density" for deer according to the Vermont Department of Fish and Wildlife — it's not hard to see why forest diversity has plummeted.
The ultimate goal of Donn's management is to create a diverse forest with "old growth-like" characteristics, but in a shorter time frame than 100-150 years. Old-growth forest is characterized by trees covering a complete range of ages. There are openings where aged trees have fallen, allowing sunlight onto the forest floor to stimulate the growth of plentiful seedling trees. There are also standing dead trees and much dead wood on the ground, creating a plethora of ecological niches as they slowly decay and enrich the earth. These traits may be approximated by careful management.
The first step to achieving this is reintroducing species diversity, and the overabundance of beech must be addressed. Donn pointed out various sites where different methods of beech control had been deployed. One method is to use "hack and squirt," where a hatchet cut in a beech tree receives about a quarter teaspoon of glyphosate. This is enough to be lethal and also takes care of the beech’s ability to send up suckers (clones of themselves) from their spreading roots. It leaves the dead tree standing, which is not always desired.
Another method is to cut the beech trees and leave a 3-4 ft high stump. The tall stump somehow inhibits the growth of suckers — mostly — and the method doesn't use glyphosate. However it involves time-consuming hand-cutting. It's not an approach that lends itself to logging by machine. In another area, the group viewed a machine "cut to length" operation where groups of trees had been cut as one. While it's efficient, Donn found that the machine tended to over-process the tree crowns, leaving a woody "thatch" that prevented the growth of seedling trees.
The most desirable method was to cut unwanted trees and leave multiple intact crowns on the ground. Seedling trees growing up through this tangle of branches are protected from deer. In fact in several locations nicely regenerating oaks and red maples greeted the visitors.
The tour was by no means limited to the beech and deer quandary. There were several vernal pools along the way, some already dried out, and one long pool still holding water. Donn recounted times when he moved salamander eggs to save them from drying and stressed the importance of never allowing equipment to leave big ruts that collect water. In the spring amphibians are lured into laying eggs there, only to dry up before the tadpoles have matured.
Part of the land that had not been logged for a long time is set aside as a reserve, meaning no management at all. Here Donn pointed out a big yellow birch that was 24 inches in diameter and large maples and oaks that he estimated were 100 to 110 years old, as well as a large fallen hemlock providing wildlife habitat diversity. This area supported a "great canopy of healthy trees" that will live for a long time. He enlarged on the issue of forest reserves, noting that to supply the wood needs of the US as a whole, the desired goal is one-third of forests as industrial woodlands, one-third in forest reserve, and one third in sustainable management. In his experience, the one-third in reserve is lacking as landowners just don't incorporate this in their management goals. He is working with clients to change that.
Among notable trees was a single mature black cherry, a species that is not rare but not abundant. He recounted finding a bear sitting in the crown of this tree, breaking branches and stripping the cherries with its teeth. All it took was one fruiting black cherry to motivate this bear — it's such an important wildlife tree. Black cherries need sun, and wildlife biologists recommend clearing around them so they can thrive.
Donn also pointed out a red maple with a shaggy bark peeling in vertical strips. This is one of the few Vermont trees with a shaggy bark that provides roosting habitat for bats. There is now added incentive to preserve such trees since the Northern long-eared bat, among others, has declined to the point of being endangered. Another stop focused on a huge old sugar maple about 4 ft in diameter. He had cautiously cleared part way around this tree to give it more sun, mindful that sugar maples are sensitive to being shocked. Too big a change in sunlight might kill it.
This land is also hosting a couple of science projects. They are based around grave concerns for the future of Vermont forests in the face of climate change. Our signature sugar maple, for instance, is intolerant of drying and requires a deep rich soil that is constantly moist. It is not expected to do well. Can our less tolerant trees be replaced by species already attuned to a hotter climate? A study of Assisted Tree Migration in partnership with the University of Vermont is seeking to explore this question. Various tree species from areas 100 miles to the south are planted here and are being monitored for their ability to survive in Vermont as the climate warms. A parallel study is following 100 oak seedlings grown from acorns from 10 different locations as far south as North Carolina. The provenance of each acorn is on file at UVM. Donn has already noticed differences in when they emerged from the ground, their leaf size, etc. Native oaks growing in the same plot serve as a comparison.
Since his land is very favorable to growing oak trees, Donn also has his own study going. He has tagged about 250 oak trees in all size classes and will monitor them for as long as he is on this land. He is studying how they respond to changes at their sites, for instance as they get more light exposure when nearby trees are cut. Ten of these oaks are impressive — about 30 inches in diameter.
Finally as the group returned to the starting point, Donn pointed out the area around his house where he had performed a 1.5 acre patch cut, mostly of sickly "pasture pine" and beech, some 12 years ago, leaving a few good trees for habitat structure. It has regenerated into a young forest of 11 hardwood tree species, including sugar maple, pin cherry, black cherry, red oak, birch, aspen, and more. He explained that there were too many young trees for the deer to eat them all. From his deck one morning he counted 20 different bird species in 10 minutes with the help of the iPhone app Merlin that identifies birds by song. In time this will become a Northern Hardwood forest and, if there is no destruction by future generations, perhaps a demonstration example of old-growth forest.