- This is with Hanusia Higgins.
She is with the University of Vermont
and will be presenting today
about the Impacts of Emerald Ash Borer Management
on Northern Hardwood Forest Dynamics.
- Hi, my name is Hanusia Higgins
and I'm a masters student here at UVM.
Today, I'll be talking about my progress so far
in studying the Impact of Emerald Ash Borer Management
on the Northern Hardwood Forest Dynamics in New England.
So invasive pests are a major issue in U.S. forests,
I'm sure all of you already know.
And as you can see from this map,
they're especially concentrated here in the Northeast
and because our North American tree species
aren't as well adapted to deal with these pests,
they can be much more destructive than native ones.
This map uses data from 2012
so they're even more invasive pests these days
such as the spotted lantern fly, which was first discovered
in Pennsylvania in 2014.
But one of the most devastating insect pests
is the emerald ash borer or EAB.
And I'm sure many of you are very familiar with this pest
but for those who aren't,
I'm going to provide a brief overview
before I get into talking about my project.
So EAB is a metallic green beetle
that's originally from Eastern Asia
and it was first discovered here in the U.S.
in Michigan in 2002, although we now believe
that it's been here since the 1990s.
EAB attacks ash trees
and all of the North American ash species are susceptible
to varying degrees.
EAB kills trees by feeding on their phloem layer
which transports nutrients throughout the tree
and this feeding basically cuts off the tree's
nutrient transport system
and it can die within a few years once infested.
So on the left, you can see an example
of the feeding tunnels that EAB creates
and on the right, you can see how this pest
not only affects ash trees in forests,
but also those in urban and suburban environments.
So for example, this street in Toledo, Ohio
was decimated by EAB in only a few years.
And as you may have guessed from the title of my talk,
EAB isn't just in the Midwest.
Of course, it's spread to over 35 U.S. states
and five Canadian provinces.
These states are represented
on this map by the green or blue overlay.
And I do have to mention in case anyone isn't aware,
one reason that it's been able to spread so quickly
is that humans disperse it by moving firewood
that's infested with EAB and as my advisor likes to say,
EAB can travel as fast as 65 miles per hour
down the highway in the back of a truck.
So if you take away nothing else from my talk today,
please just remember to not
move your firewood long distances.
So why do we care about EAB?
There are actually a lot of reasons to care about it.
So ecologically, we're not just losing ash trees.
There are ripple effects throughout the ecosystem
when we do lose those ash trees.
For example, one study in Michigan found
that forest hit hard by EAB had more invasive plants
colonizing the areas where ash trees had been.
So it can trigger this kind of invasion pathway
for other invasive species to come in
and further impact these forests.
And economically it's pretty expensive
to treat and or remove so many trees.
One study in 2010 estimated those costs would exceed
at $10 billion and the area that EAB has invaded
is now larger than that study projected 10 years ago.
So it's been very expensive and black ash in particular
is a very important cultural resource
to several indigenous tribes,
including the Abenaki here in Vermont
who use black ashwood for their traditional basket making.
And unfortunately, black ash is one of the species
that's hit the hardest by EAB.
So there's a lot motivating people.
We actually doing to try to save our ashes.
There have been several approaches.
So chemical treatment involves injecting ash trees
with an insecticide that kills the EAB feeding on it.
This is effective, but it's also costly.
It's temporary because insecticide
has to be reapplied every few years
and it's a tree by tree solution,
it's not a landscape level solution.
Biological control involves introducing EAB parasitoids
from its native range to control its population here
since it's lacking in natural enemies in the U.S.
Several parasitoid species have been
successfully released in the U.S,
but at this point they haven't been able to get EAB in check
to the point where it's a tolerable
and non-fatal pest to most ash trees.
Genetic programs are breeding EAB resistance in ash trees
and they're making some progress,
but that is more of a long-term solution
and it's not going to save the ash
that are in our forest and towns and cities right now.
However, I do want to highlight
that there is some level of natural resistance
to EAB among them North American ash species.
Most of them die, but not all of them do
and that's important and it does vary between species.
And I will be focusing on forest management techniques
which encompass a wide range of strategies for a while.
The phloem reduction technique
of cutting down the largest ash trees
because they have the most real estate for EAB was promoted,
but that didn't end up reducing EAB populations,
it just reduced ash populations.
And one important point to keep in mind
is that the management of a forest pest
can have a larger impact on the forest than the pest itself
or even just a different kind of impact.
So what do we know about this issue right now?
We know about the direct impacts of EAB on ash trees
and the communities they're in.
We know about the impact of management
for other invasive pests,
such as the hemlock woolly adelgid,
which has similarities to EAB.
And several studies have predicted the effect of management
for EAB on our forest using surveys and models.
But what we haven't had yet is information
about the management strategies that are actually happening
that are already in place and what impact those practices
are having on our forest.
And that's the question that I'm trying to answer.
So the overarching goals of my study
are first to quantify the effect of management practices
intended to mitigate impacts of EAB
on the force of New England.
And then I'll use those data to create ecosystem models
of forest development, following EAB invasion
and the associated management practices.
And finally, I'll use these models
to develop a decision support tool,
assisting stakeholders in managing their forest
for the future of ash trees
and more broadly for the communities
in which they grow.
So right now, I'm right in the middle of the first goal
in analyzing my data and I'm still in the beginning stages
of the second goal.
And once those are completed next year,
I'll use them to inform that third goal
of creating the decision support tool.
This summer, I sampled northern hardwood
and rich northern hardwood forest throughout New England
and they contain a relatively small
but significant component of ash, primarily white ash.
Some of those forests had been harvested in response to
or in anticipation of EAB
and others had not recently been harvested.
EAB was confirmed to be in some of those forests or nearby
and other than them, it hadn't reached yet
so those are the factors that I was considering.
And within those forests, me and my field technicians
used 10th acre sampling plots to capture multiple levels
of forest structure and composition
from the overstory to the understory,
stumps, snags, saplings, deadwood
and of course, what was cut in harvested areas.
We also assess the health of any ash tree
over an inch in diameter
to monitor the actual EAB component
and we did that using an ash health assessment protocol
developed by Tiffany Knight from the U.S. Forest Service.
With a lot of assistance from various people and agencies,
we were able to sample forest across new England in Vermont,
New Hampshire, in Western Massachusetts
and Western Connecticut.
There was a range of land ownership represented
including state, federal and private lands.
About half of those sites had been harvested
with EAB in mind prior to sampling
and the other half had not.
While we were out in the field this summer,
we found a variety of conditions
from some not so healthy ash, such as on the left
where you can see a lot of the bark
is flaking off the trunk that ash doesn't look so great
and then we did see some pretty healthy ash as well
which is always nice.
And within the harvested sites,
we saw a large variety in the treatments
that had been applied for EAB management.
So these treatments range in intensity
from removing just a few trees
to removing virtually all the ash trees
plus other species as well since EAB management
was usually not the only factor motivating these harvests.
And the type of harvest seem to correlate
with the motivation for that harvest.
So for example, ecological reasons,
if they were the primary motivation
potentially promoting future ash regeneration,
there would be certain civil cultural techniques
geared towards that or on the flip side,
managing the forest to transition away from ash.
For economic reasons, of course,
white ash is a highly valuable wood
and it's much more challenging to harvest
after it's been killed by EAB
so a lot of these were preemptive harvest
and at least part of the motivation was
to get that valuable ashwood out of the forest
before EAB was going to kill most of it, if not all of it.
And then safety reasons were also a consideration.
So dead ash trees falling into roads and falling on cars.
We don't really want that.
So in the stands where there were roadside areas,
we saw some of that as well.
And I only sampled in forest,
not any urban or suburban areas,
so we didn't get any of those reasons or interactions,
but within the forest and within those private and public,
federal, and state lands,
there was a lot of variation in the strategies.
With that being said, there was kind of a trend
and the most common treatment that we saw
was creating roughly third acre gaps
combined with thinning throughout the stand.
And a lot of these treatments,
which had been cut ranging from 2013 to this past winter,
we're still using that flow and reduction strategy
of removing the largest trees preferentially,
which has since been proven to not be effective
as I mentioned earlier.
So, as you might imagine,
there's a lot of data to sort through from this summer,
and I'm still working on analyzing it
to find those larger patterns,
but for now I'm taking a first look
at what is happening in terms of harvesting.
So up top, you can see the basal area of cut ash trees
within harvested plots and below the proportion
of basal area harvested in each plot.
So you can see the spread from just some of the ash
in a plot harvested to all of it.
Now, this is something that you'd probably expect
and the data does confirm
that the basal area of ash left standing and alive
in the harvested plots was significantly lower
than in the unharvested plots.
So these management practices
are significantly reducing the amount
of mature ash in these forests and right now,
I'm also extending this analysis
to look at other overstory species as well.
And looking at one more variable for now,
which is the number of seedlings per square meter
because that regeneration
represents the future of these forests.
I plotted out here against the proportion of ash harvested
which I use as a proxy for overall harvest intensity.
And again, this is a very preliminary result,
but a couple of trends that you can see here
are sugar maple seedlings decreasing
and red maple and American beech seedlings increasing
with increased harvest intensity.
And like I said,
this is just the start of analyzing these data
and I'll continue to do so in the coming month.
So what is next for this project
besides continuing to dig into that data?
As I briefly mentioned
when I talked about my goals for this study,
I'll be using the data
with the forest landscape model LANDIS-II
to simulate these various ash management regimes
that I encountered this summer
and also to see how they might interact with climate regimes
in these four counties, which I highlighted here.
So it's Orleans and Caledonia counties
in Northeastern Vermont and Bennington County, Vermont
and Berkshire County, Massachusetts to the South.
And I picked those because they had the most data points
for my study in those counties,
but there's the benefit of kind of looking
at these two different areas with different
economic sectors around forestry,
different forest types a little bit,
even though they're all northern hardwoods definitely,
getting more of that little bit of the oak component
in the South
as opposed to that really rich northern hardwood
in the North.
So it'll be an interesting kind of microcosm
to look at these two areas.
And then I'll be translating these results, as I mentioned,
into an accessible decision support tool to help foresters
and land owners and land managers understand the impacts
of their management decisions on ash
and on the larger forest landscape that ash exist in
and to help inform their decisions going forward.
So these are my references.
And finally, I would just like to thank everybody
who helped me with this project
and is continuing to help me with this project.
So my advisor, Tony D'Amato and Nate Seger
with the U.S. Forest Service who originated this project,
my committee members, Jen Pontius
and Yolanda Chen here at UVM.
My field technicians
who I worked with kind of a rotating crew
of undergrads and recent graduates from UVM
who were all excellent and really helped me out
in collecting all this data this summer
amid COVID logistics.
And speaking of COVID logistics, as you might imagine,
it was not the easiest to coordinate
doing field work this summer,
especially across a bunch of different properties
in different states with different management.
So I have a lot of people to thank for
helping me out with that
and their willingness to help and their interest
in this project has really made it possible.
And finally, I'd also like to thank my lab,
the civil culture and applied to forest ecology lab
for always being a good sounding board
and helping out with any questions anybody has.
And thank you all for listening.
- One question from MSS.
Thanks, Hanusia, did you notice any difference
in the harvest intensity type based on region
or was it more dependent on local conditions and motivation?
- Yeah, that's a great question.
There definitely were some differences.
I didn't like formally analyze this, but just anecdotally,
there was definitely more...
There were kind of differences between
I would say more so between private and public ownership
so a lot of the state forests were doing things preemptively
and doing kind of a more holistic management approach
whereas some of the private properties
that I sampled on were a little bit more focused
on like the economics and removing ash.
And then definitely there were more harvested areas
down South which makes sense
because EAB has only been in Vermont
for a couple of years, but it's been in Massachusetts
and Connecticut and New Hampshire for longer.
So further South, there was definitely more harvesting
that had occurred further in the past
and then up North, it was happening more recently
and maybe it was a little bit more new information.
And it looks like Jen has a question as well in the chat
about how common it is for landowners
to actively manage for EAB
and how widespread it is as a management strategy
across public and private ownerships.
So I don't know if I can speak to like the overall trends
because I really just know about the sites
that I sampled in or was considering sampling in,
but it definitely seemed to play a role
in a lot of the harvest on public lands
and I only sampled a couple of places
that were privately owned by individual landowners,
some of them were also owned by land trusts,
but within the private ownership,
I think it probably depends a lot on
the landowner's relationship with their forester
or with a local land trust
or other informants or kind of knowledge brokers
that are advising them on what to do.
And then within the public state parks and forests,
it was pretty similar across the board, I would say,
within each state they kind of had a similar approach.
- Thank you, we have time
for maybe one or two more questions.
We have a question from Rick Dyre.
Were you able to determine what percent of the harvesting
was recommended and implemented
as part of a forest management plan?
- Yeah, so I would say,
if I'm understanding the question correctly,
pretty much all the harvests
were part of a forest management plan.
I'm not sure if you're asking
whether it was like a part of a plan
versus not part of the plan or like what percentage
of basal area was harvested,
but the way I'm reading this it was all of them pretty much
had a forest management plan in place
and we're working from that.
Or I guess I should say they had like a harvest plan.
I don't know if that was part
of a larger forest management plan
that's kind of overarching,
but I mostly had access to the harvest plans.
- And I don't know if this is somebody
you can tell from your work, but from Dave Wilcox,
what is the tendency for white ash
to be more resistant to emerald ash borer?
- So that's not something that I personally am studying,
but based on my research and what I've read about it,
it seems like every ash species has at least some level
of resistance within the population
and it's just pretty rare
in most of the North American species,
but there have been some recent studies
showing that white ash does seem to be more resistant
than for example, green ash and black ash
so it seems like there's a higher level of resistance
within that species.
And in terms of what's causing that,
I know that's still a subject
that's very much under investigation,
but it seems like there may be a role
in the chemical ecology
of attracting versus repelling EAB,
and also kind of responding to EAB
once it infests those trees.
- From Norman Junior,
I apologize if I'm pronouncing that wrong,
the St. Regis Mohawk Trail
will be doing some crop tree releases
of black ash seed trees this winter.
Do you have any recommendations
and then also how often
was a consulting licensed forester involved from Rick Dyer?
- So for the first question,
I personally don't feel comfortable
making my own recommendations
based on this research so far
cause like I said I'm still in the early stages,
but I will share...
Let me just try to find it.
If not, I can pop it in the chat later,
but there is a document that my advisor Tony D'Amato
as well as several collaborators
from the Forest Stewards Guild
and the Vermont Forest, Parks and Rec Department
and Vermont Land Trust put together,
that's 10 recommendations for managing ash
in the face of emerald ash borer and climate change
and I think that has a lot of really great information
so I'm gonna try to put that in the chat, but if not,
you can also look it up and it's a great concise document
with management recommendations.
And in terms of how often a consulting
or licensed forester was involved,
I think pretty much in every case,
I don't think I sampled any areas
that didn't have a licensed forester involved.
That's not to say that they're not out there,
but just in terms of the kind of network
that I was working through to sample these sites.
And I also should mention,
I don't know if I mentioned this in the talk,
but all the sites that I sampled
had at least about 15 to 20% ash by basal area
so that definitely influenced things
so areas with just a little bit of ash
weren't really represented.