When Jerelyn and I bought our mostly wooded 160-acre farm three-and-a-half years ago, we began the long-term process of bringing the farm back into production and improving the health of the woodland. I’ve written previously about the farm, where last year we produced, among other crops, 2,000 pounds of heirloom pumpkins for a local brewery, but we’ve also been focusing on the forest, which comprises roughly 90% of the property.
Our woodland had never been managed before we bought the place, though it had been logged periodically. It was overgrown with stunted trees growing too close together, and various invasive plants were gaining a foothold in the understory. Our forester, George Weir, developed a forest management plan (required to put a parcel into Vermont’s Current Use Program), and we carried out a stand-improvement timber and firewood harvest, ultimately removing nearly 100 truckloads of logs.
Our timberland is healthier, now, though the work is really just beginning—and one of those steps raises some interesting questions about the role we should be playing in adapting our woodlands to a changing climate.
Dealing with invasive species
Some of our initial work in the woodland is to remove invasive species. When I hike through the woods I keep an eye out for barberry, buckthorn, oriental bittersweet, and Japanese knotweed. Our knotweed problem is confined to a low area below our house, and I spent several weekends last year fighting that back—it will be a huge ongoing challenge! I’ve been cutting back oriental bittersweet whenever I see its sinewy vines strangling our trees, but the understory invasives, most noticeably barberry and honeysuckle, have so far mostly taken a back seat to other priorities on the property.
My efforts this year to deal with those understory invasives will be aided by an amazing tool I bought last year: the Canadian-made Extractigator. The rugged hand tool has grippers that clamp onto the stem of buckthorn or any woody plant, and a fulcrum provides leverage allowing you to easily pry it out of the ground, roots and all. Watch out invasives!
Assisted migration of forest ecosystems
A bigger, longer-term project at our place is more controversial. My plan, over time, is to plant tree species in our woodland that are better adapted to climates somewhat further south. The idea is that as the climate warms, species that have evolved for our current climate may have a hard time adapting to changing precipitation patterns, warmer winters that fail to kill pests, or other impacts of climate change. We (humans) may have an important role to play in planting tree species that will help our forests adapt a changing climate.
Many of our dominant trees species in New England are faring poorly already. American beech (Fagus grandifolia) is affected by beech bark disease, a condition caused a one-two punch of a scale insect and a fungal infestation; this is having a devastating impact on the beech trees on our property—see photos.
White ash (Fraxinus americana) is dying off in our woodland due to ash yellows, a disease caused by a microorganism known as MLO (mycoplasmalike organism) that infects the living cells of the trees. As if this isn’t bad enough, another insect pest that strikes fear into the heart of foresters, the emerald ash borer, is spreading in the Northeast and expected to wipe out most ash trees within a decade or so.
Eastern hemlock (Tsuga canadensis) is facing attack from the hemlock woolly adelgid, a tiny aphid-like insect that feeds on stored starches in the twigs, weakening and often killing the trees. While the impact has been greater in southern New England, this insect pest was found a few years ago in our home town of Dummerston, Vermont.
Some suggest that even Vermont’s ubiquitous sugar maple (Acer saccharum) may become susceptible to a warming climate and die out over time.
There’s a very useful resource showing how ranges of tree species are expected to change over time, the Climate Change Tree Atlas, an online tool created by the Northern Research Station of the National Forest Service.
On the Climate Change Tree Atlas you can see, for example, that by the end of the century white oak (Quercus alba) will be a far more common tree in Vermont forests than it is today.
My plan is to plant more southern species, such as white oak, bur oak (Quercus macrocarpa), and shagbark hickory (Carya ovata) on our property over the next few years. The hope is that as the climate changes, the increased biodiversity in our woodland will help that ecosystem adapt and remain healthy.
Without native (but more southern) species entering the ecosystem, there would be greater risk that invasive species, which are rapidly gaining a seed-bank foothold in the region, would take over the ecosystems.
But is this “assisted migration” a good thing?
I’ve been polling various people, including my BAC students, about the wisdom of intervening with nature, and the response is definitely mixed. I’m mixed about it myself.
From past experience, we’ve seen all too often that human efforts to mess with Nature often backfire. Even when our intentions are good, we can do more harm than good. So there’s an inherent resistance to helping speed a migration of plant species that would normally take hundreds or even thousands of years.
Why not just leave Nature alone and let the more suitable species gain a foothold as the climate warms? Because, in my opinion, the warming that the Earth is experiencing is happening too rapidly for the very slow species range extensions (that would occur with more gradual changes in the climate) to keep up.
Since we’ve introduced so many invasive species into the seed bank of our land, I fear that those invasive species will be able to quickly colonize an ecosystem when the keystone species die off—as is happening in the West with whitebark pine (Pinus albicaulis) and some other conifers.
What do you think?
As a environmental biologist by training, I think a lot about our ecosystems. On our own farm I want to do the right thing for the land, and I think that includes not only working to get rid of invasive species but also introducing some more southern species that are not yet common in this area. Is that a good idea?
Resilient design extends beyond our buildings and communities to include our ecosystems. If we want more resilient ecosystems, do we (humans) need to intervene? I think so, but I’d love your thoughts. Post any opinions you have as comments below.
Along with founding the Resilient Design Institute in 2012, Alex is founder of BuildingGreen, Inc. To keep up with his latest articles and musings, you can sign up for his Twitter feed. To receive e-mail notices of new blogs, sign up at the top of the page.