So as we all know,
climate change is one of the bigger threats of our time.
And in addition to increasing or changing our precipitation
and temperature patterns, we're also seeing increases
in the frequency and the severity of forest disturbance.
So we're all familiar with the increases
in wildfires out west, but we're also seeing increases
in insect outbreaks and then disturbances,
like wind disturbances and tornado disturbances.
And for foresters, when we have these disturbances,
the common management response
is salvage logging and salvage logging,
for those of you who don't know
is the removal of commercially valuable wood
following a natural disturbance.
So this image is a photo
of a salvage logged area following a tornado disturbance.
And you can see that there were lots
of stumps remaining from snapped trees
and all of the valuable woody material has been removed.
So salvage logging is a very controversial topic
and there's lots of reasons why we do it.
The primary reason is to avoid economic losses.
So as you might imagine
if you've been growing a wood lot for 40 years,
and then it randomly blows down in an unexpected wind event,
you might wanna salvage some of that material.
So that's the main reason.
But there's also some ecological reasons
why we might salvage log.
So some studies suggest
that by salvaging, we can reduce the risk
of insect population explosions
as bark beetles are often attracted
to large amounts of deadwood.
And if those populations get too high,
they might start feeding on live trees as well.
And then of course,
we might be able to reduce fire risk through salvaging
but this is only really effective
if we're moving the fine weighting material
in addition to the larger logs.
So there are lots of cons to salvage logging as well.
And this book kind of looking at the ecological consequences
of salvage logging kind of outlines many of those cons.
But the issue with salvage logging is that often,
the disturbance is a lot heavier than a traditional harvest.
And you have kind of a compounded disturbance
where you have this natural disturbance that occurred
and then another management disturbance on top of that.
So some of the risks here involve damaging soils,
which of course, can happen in any sort
of forest harvest where you have compaction
and rutting erosion.
So that's an issue.
And then there's lots
of substrate for deadwood-dependent species.
So of course we have a lots
of insects and fungi that kind of rely on deadwood.
And when you're removing that, that substrate is lost.
And then finally, it might impede tree regeneration
and forest recovery.
And this is the point
that I'm really gonna focus on for this talk.
So I had three research questions.
My first question is
does salvage logging alter regeneration abundance
in species composition?
And here this is kind of the question
that's guiding this research.
So I'm really interested in seeing how regeneration differs
between stands that were salvage logged
and stands that just were impacted by a natural disturbance.
And then my second question is does blowdown
in salvage conditions influence browse pressure?
So as was mentioned in the first talk today,
deer and moose browse is a big issue in the northeast.
So there's, yeah, there's some differences in how blowdown
and salvage conditions might might influence that.
And then my final question is
does salvage logging influence microclimate conditions?
And this is actually an element
that I'm not going to talk about much today
as these results are still pending analysis.
So I was really lucky I got to do this research
in Baxter State Park, which is known
for being the home to Mount Katahdin pictured here.
Ultimately, however, my research did not happen
on top of Katahdin.
So this is a map of Baxter, and my research happened
in the far northwest corner where that kind
of red outline is.
And that's the scientific forest management area
of the park.
So Baxter does have this one portion set aside
to demonstrate sustainable forest management practices.
And there was a tornado that struck there in July 2013
and it damaged about a 200-hectare swath of conifer forest.
And following that,
there was a partial salvage operation that winter,
which kind of created this perfect study opportunity
where you had areas that had been salvaged,
areas that were impacted by the disturbance and blown down
and then some like control areas.
So because of that nice setup,
there were two papers published immediately
following the salvage and tornado disturbance.
And one of those papers was just looking
at the forest structure of these areas.
And then the other was looking
at that response to bark beetles.
But then nine years later,
I came back and revisited these treatments.
So we have the control treatments,
which are what's undamaged by the disturbance blowdown,
which is what was left
from the tornado and then blowdown and salvage.
And as you can see,
there's some very clear visual differences
pretty much right away.
So this summer, our sampling approach,
we established 48 plots, so 16 plots per treatment.
And in each of these plots, we established four subplots
and we measured all the saplings in each
of these subplots and recorded diameter, the species,
and then did a quick browse assessment on each sapling.
So this is a photo of a red maple sapling
that we would consider browsed because as you can see,
the top is all kind of frayed and bitten off.
And here we are just doing a browse, yes or no.
So this one would be considered yes.
And I'll also mention
that we're only looking for moose browse here.
Deer browse is,
there just aren't any deer this far north in Maine.
And then hares are also present and they do browse saplings
but we weren't as concerned about
how they might be impacted by the disturbance.
And you can tell apart hare browse from moose browse
because the the cut of their browse is much more sharp.
So we also did a structural assessment.
And to do this, we used LiDAR data to assess canopy closure.
And then on the ground, we did woody debris transects.
So we measured the height of each piece off the ground.
We measured the diameter,
as this research technician is demonstrating,
and then decay class
on the five-point scale and species, if we could tell.
So getting into some results here.
So all three images pictured here are examples
of what we're seeing in an example salvage plot.
So this first photo on the left is a photo of aerial imagery
like immediately following the salvage operation.
And you can see that there's these salvage roads kind
of in the center.
And then along the outskirts
towards the top, there's more blowdown area.
And then this middle photo is an example
of the LiDAR imagery that we used.
So this was data taken
in 2017 from like the USGS national map.
And you can see
that it shows the structure of the salvage plot really well.
So there's some kind of roughness around the surface
and then a few standing live trees and snags.
And then this photo on the left is what we are seeing
or on the far right I guess is what we are seeing
in our plots this summer where there's a lot of,
it's very open, a lot of herbs and ferns in the understory
and just like a few remaining snags and live trees.
So the conclusion from this, we found
that canopy closure did differ between all three treatments.
So the control, as you might imagine,
is completely closed canopy.
Blowdown is somewhere in the middle
and then salvage is the most open.
Salvage logging, often they will cut live trees as well.
So that's why this is a little bit more open
than the the blowdown area.
So getting into the results on tree regeneration,
this was a little bit surprising.
We found that the blowdown in salvage areas
tended to have very similar regeneration patterns.
So the control is the one outlier here.
There were not very many saplings regenerating
as you might expect.
There was no disturbance that happened there.
But then the blowdown in salvage areas had a lot
of regeneration, especially in these smaller size classes.
So on this graph, there's size class
on the x-axis and then the total saplings on the y-axis.
And you can see that there's a lot
of hardwoods in the blowdown in salvage area
whereas the control is more dominated still
by balsam fir, red spruce.
So the primary interesting thing that we found
was this evidence of a caging effect.
So often to prevent moose or deer from browsing saplings,
we might construct a cage around gaps
if we have enough money to do that.
And yeah, this is what that might look like.
They are very expensive and not incredibly practical
for a lot of forest managers, but they are effective
at keeping moose and deer out and letting the saplings grow
to maturity before they get browsed.
But we hypothesize that the blowdown
might kind of create a similar sort of caging effect.
So this is what we are seeing on the ground this summer,
and immediately following the tornado, there's just all
of this deadwood that kind of acts as a natural cage.
So it might be a little similar to like a slash pile
that you would put up around a gap
but this blowdown kind of created a natural slash pile.
So our hypothesis was that in areas
where you have greater woody debris volume
and maybe greater heights of woody debris off the ground,
we might see reduced browse.
And to show that,
we first had to measure the woody debris volume
and this statement at the bottom should be no surprise.
Of course there is more woody debris volume
in the blowdown area where there was a tornado
and those trees were not salvaged.
So that's very clearly shown in this chart.
The blowdown area has about like five times
as much woody debris as the salvage and the control,
which are more or less equal.
But we also found
that there was more elevated woody debris in the blowdown.
So again, this is nine years following the tornado
and the elevation of the witty debris is still there.
And you can see that in the control and the salvage areas
most of the woody debris is along the bottom still
on the ground.
So putting this together, we did determine
that there was evidence of a caging effect.
So this chart shows the woody debris volume along the x-axis
and then the proportion of browse saplings on the y-axis.
And you can see that where there are more,
where there's more woody debris volume, most of these
like blue dots, there's also a lower proportion of browse.
And where we have less woody debris volume,
we're seeing higher proportion of browse.
And we're also observing kind
of a difference here in treatment.
So the blowdown plots are all kind of grouped
in this side where you have more woody debris volume,
less browse control is the green areas
where you have less woody debris volume
and also less browse.
And then sap and then salvage areas have the most browse
and also the lower amounts of woody debris volume.
And we're seeing a similar trend with woody debris height.
So again, where you have higher woody debris height,
you're also having lower browse.
And so taking this together,
we are seeing less browse in the blowdown plots
or rather more browse on the salvage plots,
which is pretty clear by this chart.
So to conclude, for regeneration,
we are not seeing super clear differences in abundance
or composition between the salvage and the blowdown plots.
Structurally, we are finding
that there is still a big difference
between blowdown and salvage.
So blowdown does have much greater
woody debris volume and height.
And then looking at browse,
we are finding that browse damage is far more severe
in the salvaged areas.
And then, of course, our microclimate results
are still pending analysis.
So the overarching conclusion here is that woody debris,
it's impeding access
by moose and therefore reducing browse.
And I'd just like to quickly thank my collaborators,
my funding sources, the folks
at the SMFA who really helped provide housing
and like allowed this project to get started.
Statistical help, LiDAR assistance I've received
and then all of my wonderful volunteer field assistants.
All right. Any questions?
(audience clapping)
(audience member speaking indistinctly)
Yeah, yeah, so that's a great question.
So yeah, there was a paper published that kind
of just looked at that structural differences
immediately following the tornado.
So we do have some data there.
The plots are not in the same place as those plots
so we can't like track the specific areas very closely.
But yeah, I mean I think the interesting thing
we found this past summer is that there is still
a significant height to a lot of this deadwood
and we're not seeing very fast like decay rates.
Most of the species were still in like the decay,
like class one or two category, which is fairly undecayed.
So yeah, I mean, it has been
like nine years since the tornado
and I can't really project how it will change
into the future, but it does seem like that structure
of the blowdown is remaining pretty solidly,
whereas the salvage is the main area that's changed.
It's just like far more open
and it has a lot of understory growth
in ferns and like raspberry and blackberry.
So yeah, I don't know if that answers that.
Yeah. Question in the back.
[Audience Member] I have two questions.
First is (indistinct).
Yeah, yeah, that's a good question.
So this was actually a unique salvage operation
because they had a protocol
in place before the storm happened.
So they did have a salvage plan
and I don't think it was too much based on access.
I think they salvaged a portion of it
and then they did intentionally leave some areas
that were left in blowdown.
But I don't know too much
on the details on why they salvaged where they did.
But yes, generally on the fields,
the blowdown in salvage areas were very intermixed.
I actually do have, this is kind of like a rough map
of the locations, so the salvage areas are in red
and you'll see that the blowdown areas are kind
of like surrounding that in blue.
So yeah, that's kind of the distribution
of where that's happening.
Yeah. Remind me your first question.
[Audience Member] What was the plot?
Oh, yeah, yeah, they were fixed variable
radius sapling plots.
Yeah. Or fixed radius.
Yeah. Yeah.
[Audience Member] How big?
They were 2.8 meter radius subplots.
Yeah, four-foot plot.
And then we did 100-meter woody debris transects.
Yeah. Yeah.
[Audience Member] So volume
but slow down, we expect that, but also be (indistinct).
Yes. Yeah, that's a great question.
That's actually what we're working on right now.
We're kind of we're working on a model to show
what is the most influential factor.
And yeah, right now it seems like volume might be the more,
like a better determinant of browse.
But yeah, we're still trying to figure that out.
[Audience Member] There's a separate question.
Is there any interest in looking at the different types
of communities that (indistinct) versus the (indistinct)?
Yeah. Yeah, that would be a great question.
We haven't looked at that.
I mean, there is the insect study done, but yeah,
nothing into birds yet.
All right. Thank you.
(audience clapping)