By Rosemary Ford and Caitlin Agnew
This article has been edited for length and clarity.
Beech leaf disease is the latest threat to the state’s beech trees. It’s quickly spread across the state and could have several environmental and human impacts. Here to discuss what’s happening is Lindsay Watkins, a field specialist in forest resources for Strafford County at the University of New Hampshire Cooperative Extension.
Melanie Plenda:
Lindsay, what is beech leaf disease? Where does it come from? What does it look like?
Lindsay Watkins:
Beech leaf disease is the newest of our forest's health threats that we're seeing here in New Hampshire. It's caused by a foliar nematode. Nematodes are microscopic, worm-like creatures, so we can't see them unless we're looking at them with a microscope. But they're tiny, little worm-like deals that get into the buds of beech trees and do quite a bit of damage.
Beech leaf disease, as far as we know, came from Asia, and likely came on nursery plants or in soil that came in plants from overseas. It was first detected in Ohio in 2012, made its way east pretty quickly and spread up the Atlantic coast. It was first found in New Hampshire in 2022 in Deerfield, Nottingham, Durham and Madbury. Since then, it has spread pretty quickly throughout New Hampshire.
Melanie Plenda:
How prevalent is this? Are many trees in the areas you mentioned affected?
Lindsay Watkins:
It's extremely prevalent. Last year it was kind of one of those things most of the towns that I would visit in Stratford County, if I looked for it, I could find it in some places. It was very readily apparent. This year, it's everywhere. You can't miss it. The trees look almost what I would describe as kind of crispy this year. The leaves are just leathery, thick, crinkled, and just look really unhealthy.
Melanie Plenda:
Why is this a concern here in New Hampshire?
Lindsay Watkins:
One of the big concerns is that we're seeing beech leaf disease cause pretty rapid mortality in beech trees. In some of the smaller trees, we're seeing those trees die off in about three to six years. It might take a little bit longer for some of our larger, more mature beech trees, but one of the things that we have in New Hampshire as a result of our past forest management, as well as beech bark disease — which is another disease that affects beech trees- is that we have a lot of .smaller, understory, midstory beech tree, and so when you look out into a forest, most of what you're seeing in that lower layer of the forest canopy, in many cases is beech. That's going to change a lot about how our forest ecosystems look and how they function.
So you're changing the amount of light that reaches the forest floor, you're changing the humidity and moisture levels in that understory layer, you are potentially opening up space for other species to come in. Those may be native species, those may be invasive species in some cases. So there's just a lot of things about the dynamics of how our forest ecosystems work that are going to change as a result of beech leaf disease.
Melanie Plenda:
Tell us more about beech bark disease. What is it and when did that become a concern?
Lindsay Watkins:
Beech bark disease started to appear in New Hampshire around the 1950s, 1960s, and it became really prevalent. It's a more complex disease. It's caused by a combination of a scale insect that is feeding on beach bark and in the process spreading fungal pathogens.
There are actually a couple of fungal pathogens that are believed to be involved. They're native to New England and North America. The scale insect came from Europe. I believe it arrived in Nova Scotia in the early 1900s and then kind of spread south and west.
Beech bark disease is more complex in the way it works. It doesn't outright kill beech trees the way that beech leaf disease might, but it did take out a lot of our older, more mature beech trees and our forests and part of beeches’ ecology is that when a tree is stressed, or when it's killed, it puts out root sprouts. So if you kill a very large beech tree, or you stress out a very large beech tree, part of the way it's going to react is it's going to send out all of these root sprouts, and that's part of why we have so many of these smaller, sapling-size beech trees in our forest.
Melanie Plenda:
What happens if we lose the state’s beech trees? What does that look like? What impact will that have?
Lindsay Watkins:
The first thing that comes to mind when I think about losing beech trees is just how valuable they are as a tree for wildlife. Beeches produce beech nuts, which are an extremely valuable food source. They're high in fat and protein. They're particularly valuable for bears, but there's a lot of other species that rely on beech nuts as a food source as well. That's a pretty big impact when you think about removing a species that is so important to so many different species.
On the flip side of that, because of some of the challenges that I mentioned before with beech bark disease, a lot of foresters have spent many years trying to figure out how to manage beech so that there's less of it, so that we can encourage other species that might be more desirable from an economic standpoint, or even just to have greater biodiversity to grow, because in a lot of cases, you'll have so much beech in your forest that it's shading out other species, like sugar maple or red oak or other species that we want to grow. So there's a certain degree to which some folks maybe aren't heartbroken that we're losing some of our beach, but I don't think this is the way we would want this to go.We don't want to lose all of it. It's a really important species for a lot of reasons.
Melanie Plenda:
How will wildlife be affected? How will people be affected?
Lindsay Watkins:
Sometimes it can be harder to see the direct impacts to us on losing a species or many trees of a species, but beeches are really important characters, like the characteristic tree of our forest.
Think about the northern hardwood forest: You think maple, beech and birch. Those are the species that really make up that forest assemblage. So there's going to be a visual impact. People are going to notice it. It has not been detected in the White Mountains, but I'm pretty sure that by next year, we're going to start to see it throughout the White Mountains. So people out hiking are going to notice it. It's going to change, really, the look of our forests, and I think it's going to change the function of our forest ecosystems, maybe in ways that we don't even quite recognize yet.
Melanie Plenda:
Overall, how healthy are New Hampshire forests? What concerns do you have?
Lindsay Watkins:
That's a really tricky question — forest health is complex. When I think about what a healthy forest is, I think about a forest that is functioning in a way that it's providing ecosystem services for all of the species that live there — a variety of different tree species, a variety of different tree age classes and sizes, you have different wildlife that are making use of our forests for food and for habitat and getting their needs met.
I think one of the challenges that we're seeing is that we have these different pests and diseases that, in many cases, are detrimental to an entire species. So we've lost chestnut, largely lost elm, seeing our ash trees die off on a wide scale, and now it's beech. So every time we lose a species like that, it takes away some of the complexity. It takes away some of the ecosystem's ability to respond to further stress and additional disturbances. If you eliminate all the beech, you start to get to a point where your forests are made of one or two or three species, and then what's next? It becomes a little bit of a domino effect.
Melanie Plenda:
What can the average person do, if anything, about this?
Lindsay Watkins:
I wish I had some better answers. I think just being aware of what's going on and paying attention. Extension and the New Hampshire Division of Forests and Lands maintain nhbugs.org — it’s a website that has a lot of information about forest pests and diseases. You can go on there and get more information about what to look for.
If you are in the southern half of the state, we probably don't need you to report beech leaf disease. We're pretty sure we know where it is and we've got it. But if you are in the more northern half of the state and you're seeing beech leaf disease in a place that it hasn't been reported yet, please do submit a report to nhbugs or reach out to your county forester and just let them know that it's there. It's just helpful to keep track of where it is, how it's spreading, how quickly it's spreading, as we continue to learn more about it and figure out what we might be able to do from a practical, hands-on perspective.
If you're a landowner who's managing forest land, I don't think there's anything that you necessarily need to change as a result of beech leaf disease. If you're working with a forester, if you have a forest management plan, it's definitely something to consider going forward how you're going to continue to manage that forest land. If you were going to cut the beech anyway, it's great firewood. By all means, cut beech trees for firewood. If you weren't going to cut beech trees down, there's not really a reason to go out and do that just because this disease is here. It's not a situation where if we cut our beech trees down, we're going to help prevent it from spreading further.
Melanie Plenda:
So interesting! Lindsay, thank you for joining us today.
“The State We’re In” is a weekly digital public affairs show produced by NH PBS and The Marlin Fitzwater Center for Communication at Franklin Pierce University. It is shared with partners in the Granite State News Collaborative, of which both organizations are members. For more information, visit collaborativenh.org.