Welcome. Thanks, everyone, for coming.
I'm a second year Master's student here at the university,
and I've been looking
at how different silvicultural treatments
impact regeneration,
as well as understory plant community diversity
and abundance in pitch pine systems across the Northeast.
And so you may be asking yourself,
what is a pitch pine system?
They are globally rare endemic communities found mainly here
in the coterminous Northeastern United States.
They're home to multiple rare threatened endangered species,
and they're found on xeric, sandy glacial outwash.
Importantly, these are fire adapted communities
with fire dependent species
like pitch pine, shrub oaks, and ericaceous shrubs,
as luckily, Ryan has laid some the groundwork.
And so that leads me to my next slide,
as hopefully we're all well aware
that dry lightning strikes
in this region of the world are quite rare.
So the research undertaken in this study takes place
on the traditional and ancestral and current homelands
of multiple Tribal Nations,
including the Shinnecock, Unkechaug, Setalcott,
Stockbridge-Munsee Community, Mashpee Wampanoag,
Wampanoag of Gay Head (Aquinnah), Nauset, Pokanoket,
Pequawket, and Quawket Nations,
as well as the Haudenosaunee and Wabanaki Confederacies.
Pitch pine barrens have important historic, current,
and cultural value,
and the relationships Tribal Nations had
and continue to have with pitch pine barrens
are essential to their character and restoration.
Furthermore, this research is undertaken
into the University of Vermont,
which resides on the traditional ancestral and current lands
of the Abenaki Nation.
The colonization of these lands is an ongoing process,
and as a settler, I'm the beneficiary
of the colonization, occupation,
and study of Indigenous homelands.
In this research, we have a responsibility
to advocate for the sovereignty of Tribal Nations
and the return of land and financial resources
to Indigenous people.
So the colonization in the Northeast
really created some substantial changes
to fire and disturbance regimes in pitch pine communities.
They both increased and decreased
in spatial and temporal scale.
Other changes came from clearing for agriculture
and subsequent abandonment, as well as government policies
which prevented the use of fire as a management tool.
Furthermore, these systems are underlain
by very developable soils,
and so there are some very real threats
from fragmentation and development,
along with management issues
along the wild and urban interface.
Add to that novel threats from climate change,
first on our list being the more recent expansion
of southern pine beetle,
which was touched on this morning at the meeting.
So southern pine beetle is a bark boring beetle.
It's native.
It's long been in relation with hard pines in the Southeast,
and it releases pheromones
which create these aggregation conditions,
which can lead to outbreaks and rapid overstory mortality.
And so a management strategy in the Southeast
has long been the reduction of basal area
and the increase of inter-tree distance
to impact stand microclimate and tree vigor.
The northern range of the outbreaks
used to be southern New Jersey,
but in the past 10 to 15 years
with warming winters, this range has grown.
So in 2014 there were the first outbreaks in Long Island,
and as of last summer in Martha's Vineyard
off of the coast of Massachusetts.
Southern pine beetle has also been found
in traps up in Maine, so it's certainly moving.
And so this is one of my research sites.
Hopefully you can see it well.
We've got a lot of conifer crowns here
in this winter photo in March of 2012.
This is Wertheim National Wildlife Refuge
in Shirley, New York on Long Island.
The stand is outlined in white,
and so this is a barrens community,
but there hasn't been any disturbance or management.
And so, you know, the stand has really densified
into more of a closed forest condition
than it would be in a traditional barrens.
Here we are in September of 2013.
I don't know how good the visual is here.
You can start to see these light brown patches,
and so those are almost certainly the first outbreaks sites
of the southern pine beetle.
Here we are in June of 2014,
and we can see that brown has spread throughout the stand.
And so southern pine beetle wasn't recorded
as present on Long Island until the fall of 2014.
Here we are in March of 2015.
This is complete overstory mortality for pitch pine.
This took less than two years.
And because of underlying issues
with mesophication and densification,
and the lack of the right cultural fire,
prescribed fire, disturbance regimes,
there's no understory advanced regeneration of pitch pine.
So this loss of the overstory
represents a loss of seed source,
a loss of genetic diversity,
and it can really be the domino that tips the scales
into transitions to new stable states.
And so we're losing, we have a real potential
to lose these rare natural communities.
So we can see there's hopefully a real reason
why we wanna understand
how different silvicultural treatments
impact regeneration success
as we think about managing for resilience
and getting ahead of southern pine beetle.
And so that brings us, finally, to my study.
This is an observational study,
and I started by contacting a lot of land managers
across the Northeast who were very kind to talk to me
and send me information.
And I put together a list of sort of who, what, when, where.
And so I identified four different types of treatments,
which are fall prescribed fire,
spring prescribed fire, harvest and mowing,
followed by prescribed fire,
that were available across the Northeast.
And I looked at, I chose five different regions
in which to conduct my sampling.
I tried to find these treatments in at least three regions.
Only two is available for harvest.
And in each region, in each treatment type,
I had to have three replicates of that treatment
so we could get a good idea of what those treatments meant,
and only two for control.
Sampling areas were treated between 2015 and 2022,
and they had to be at least 1.2 hectares, 3 acres,
to manage for edge effects,
and also to fit the amount of plots in there
that we were hoping for.
Here is a map of my study sites,
and we took a range of different data.
Today I'm really talking about regeneration.
And so regeneration was taken at every plot.
We looked at regeneration in three different size classes
and plot sizes.
That was taken at every plot,
and then every other plot we looked at understory,
vegetation diversity, and abundance,
as well as classifying ground cover,
and looking at percent cover there,
things like mineral soil, exposed mineral soil,
leaf litter, rot,
and then taking two measurements of litter depth.
And so this speaks to the need
for, I suppose, mineral soil and reduced leaf litter depth
for successful germination in pitch pine.
And so this is hot off the press.
I finished this sampling at the end of August,
and I've been working to bring you these results.
So they're very new.
And so what we're looking at here first
are the small seedling categories.
So that's less than 50 centimeters,
only looking at pitch pine.
I used generalized linear mix model
with the Poisson distribution,
looking at treatment as a fixed effect
and site as a random effect.
And in these models we found for small seedlings,
sort of two other variables of interest.
And so the first one on the left here,
this is we're looking at the average leaf litter depth.
And so we can see as leaf litter death increases,
the, you know, predicted counts of pitch pine decreases,
again, speaking to that need for exposed mineral soil.
And on the right here we're looking,
and so leaf litter depth sort of ranges
from 0 up to like about 13 centimeters.
On the right here we're looking at the influence
of basal area per hectare,
which can range from about 0 to 100 square feet.
I'm just more comfortable with square feet.
Hopefully (chuckling) it's not a problem.
It can be up to 220 square feet in control sites,
which is really quite dense.
But we see that there is an increase
in predicted pitch pine seedling counts
as basal area increases.
It's a much smaller effect
than the leaf litter depth over here,
and so that speaks to sort of some of these sites.
These barrens communities have no overstory.
They have 0 or 10 square feet or 20 square feet,
and so that can be a limiting factor
in terms of germination.
So of course we wanna be able to find a sweet spot
where we have enough pitch pine trees that we're getting,
we're not inhibiting regeneration,
but we're also still resilient to southern pine beetle
and reducing basal areas in really dense stands.
And so of significance are the treatments,
harvest, fall fire, and spring fire.
They are significantly different than control in this model.
And we can see control is really a flat line,
and that has to do with how little germination,
advanced regeneration are present in control plots.
Secondly, we're looking at large pitch pine seedlings.
And so you can see one here on the left, or on the right.
Here on the left, again, in this model we found that,
I found that leaf litter depth is again of interest.
As leaf litter depth increases,
so do predicted counts of pitch pine fall.
And as you might be able to guess, harvest was the only
sort of significantly different treatment here.
And this speaks to how, I think,
really how successful some of these harvests were
in Massachusetts at getting soil scarification
and really exposing mineral soil.
Finally, I looked at saplings.
Saplings are, there's not a lot of them,
so this is a zero inflated model.
And what was of interest here,
which really makes sense when we think about it,
as the time from last treatment
that was used as an offset in this model,
and so the longer it's been since the last treatment,
the more likely there is to be saplings,
'cause they take some time to grow.
And we can see the mowing followed by prescribed fire
doesn't even show up on this graph,
and that's because that mechanical treatment
really prevents pitch pine
from getting into the sapling stage.
And also, you know, control here is not flatlining.
It's actually going up,
and so we did find quite a few saplings
inside control sites, but of course sapling is a size class.
It doesn't necessarily refer to the age of the tree.
And so the saplings that we're seeing in control sites
are much older than the saplings
that we are seeing in managed sites.
So, some conclusions.
We're seeing harvest and fall fire
as showing early signs of success as management strategies.
And that reduced leaf litter depth is really very important.
And so that can come from scarification.
That can also come from fire.
You know, no two fires are the same,
and so fires that smolder
and really reduce leaf litter depth
can be really successful in terms of germination.
Also, there's this sweet spot for basal area.
We don't wanna have too little,
but we also wanna make sure
that we're managing for resilience to southern pine beetle
as it moves into the Northeast here.
And next steps for me are to investigate relationships
between silvicultural treatments
and other characteristic plants
like scrub oak and blueberry,
things that have cultural and ecological value.
I'd like to thank all of my incredible field help,
as well as my advisors and committee,
and the lovely people from my lab.
And I talked so much faster, (chuckles)
so I am ready for questions if anyone has any.
Yes.
[Attendee] What's the (indistinct) basal area
that works (indistinct)?
I don't think that, like from this model,
I haven't identified a number.
I would say, also thinking about managing
for what they found in research for managing for resilience
against southern pine beetle is like 60 to 80 square feet,
you know, so I think we want it to be above 20,
but like 60 to 80 square feet could be really good
for supporting both regeneration prospects
and managing against that sort of vulnerability
to southern pine beetle.
Yes.
-I have a question. -Someone online?
[Moderator] Patch it in.
[Brennan] Hi, Brennan Baltier from the New York State DEC.
Go ahead, Brennan.
[Brennan] Did your site assessments,
were there any variables
that needed to be accounted for and their differences?
So using, I think this is what you're speaking to,
you cut out a little bit,
but I think you're sort of speaking
to how it's a regional study,
and so that really gets caught up in using a random effect.
So both the sites are random
and the plots within the sites are random effects.
So that's kind of the way that we're controlling
for how many different regions that this study spans.
But if that's not what you were talking about,
please let me know.
Yes.
[Brennan] That getting to the point. Yeah.
I was just wondering if you'd noticed
any explicit differences from site to site
that might cause difficulty in these comparisons
when you pulled 'em together
that needed to be kind of accounted for.
Sure.
I think that a lot of what is true about these communities
is true throughout the region,
and so there's certainly some change, you know,
as we move north with plant species,
some differences between inland and coastal barrens.
But overall, I think, in terms of the management
of these systems to create regeneration,
they really are quite comparable.
It's similar soils, it's really similar species,
it's similar structure.
And so I don't really see that as a limiting effect.
Hopefully doing this regional assessment
makes something that's more valuable
to the many land managers that are out there.
And that's really the focus of this project
is to give land managers actionable tools.
-Awesome. -Yes, in the back.
-So- -Thank you.
[Attendee 2] I don't think you mentioned serotiny
and how that might affect the regeneration of pitch pine
and whether a spring burn versus a fall burn
would factor into that.
Yes, one of the sort of site level things that I looked at
was serotiny, using binoculars.
Of course it was a very wet summer,
and so the pine, if you don't know, pines,
pine cones close when it's wet.
And so we did, I did find serotiny in every forest
except for Waterboro, Maine,
and I could have just missed it.
And so serotiny, for those who don't know,
closed cones that are held,
and then there's another element called pyriscence,
which is when they release their seeds after fire.
And so pitch pines can be both serotinous and nonserotinous.
Communities that experience a lot of fire,
like the North Pine Plains, are highly serotinous,
and other communities
that don't experience as much fire are less so.
So I did find serotiny throughout this area.
It's certainly not the majority of trees,
and so that sort of limits its effect, I think.
I think that maybe the fall fire was more successful
in, you know, removing leaf litter, potentially.
And so I didn't see serotiny really as a limiting effect,
but that's something definitely to think about.
Someone else, yes.
[Attendee 3] I was just wondering,
in, well, Northern New York,
and then moving into the Upper Midwest,
there are jack pine barrens
as opposed to pitch pine barrens.
And are you aware of any, like, research in those systems
that might inform your study
or how might findings from your study
inform those systems off of that interchange?
Yeah, I think, you know, jack pine is also, you know,
vulnerable to southern pine beetle.
You know, like hard pine, and as the climate warms,
you know, it's predicted southern pine beetle,
I think, you know, to be way up into Canada,
not in the far too distant future.
So I'm sure that this is something that people,
managers in those systems are also thinking about,
and that there is certainly a lot of,
I think there's a lot of potential overlap,
but I haven't worked specifically with people in jack pine.
[Instructor] We have time for one more question.
Yes.
[Attendee 4] I'm curious your thoughts on,
or your conclusions about mowing,
because it seems like here a lot of our pitch pine systems
are so fragmented that fire is just not an option,
so we try to emulate disturbance by mowing a lot of times,
but I always wonder about scarification
and if we're getting enough exposed mineral soil.
So it seems like looking at your graphs,
like there were, you know, responses from mowing,
but I'm wondering if you saw scarification
just from the process of having the mowers in there,
or if you had to do specific things.
So, while I have seen mowing,
these sites were at least a year from their last treatment,
so they would've been multiple years from mowing.
So I wouldn't say that I saw signs
of scarification from mowing.
I think mowing doesn't really have that same effect,
and it's not really possible
to reduce the leaf litter depth with mowing.
And so in my models, mowing is not significantly different
than control sites.
And so it's really not having
that same effect on pitch pine.
It's great for scrub oak.
You know, if we're really managing for scrub oak
and, you know, the rare lepidoptera associated with it,
or dwarf chinkapin oak,
you know, it definitely has potential in those things,
and these landscapes are matrices
of different types of environments,
and so mowing, I think,
can be really effective in some places,
and it can be effective probably
in sustaining these communities,
but not really so much so far
in generating pitch pine regeneration.
[Instructor] Thanks, everybody.