- [Tutor] So our final presenter
of this contributed talk is Christopher Woodall.
With the USDA Forest Service.
He will be presenting,
"Completing the Life Cycle of Trees:
Northern Forests Dead Wood and Tree Regeneration
in the Context of Forest Resource Assessments."
- [Christopher] Hello, I'm Chris Woodall
with the USDA Forest Service,
research development in Durham, New Hampshire.
My colleagues and I would like to share
some emerging results we have
in regards to assessing the dynamics of tree species
in New England.
Notably, tree regeneration in dead wood information
based on recent inventories in this region.
As an outline, I would like to provide a little bit
of context regarding tree regeneration in New England
bring in some information about recent inventories we have.
Some of the details regarding those.
Discuss some emerging results
and next steps in this line of research.
So as far as the context of tree regeneration,
we can really look at our future forest
against the backdrop of global change.
And global change is really bringing in
traditional stressors
in new ones that we haven't really seen before.
Certainly we have insects and disease.
We have a loss of winter with climate change,
coupled with episodic precipitation.
We have urbanization and fragmentation,
which can often bring in invasive species.
We have evolving forest product markets
are really changing what products are harvested out
of our forest and how we can manage them.
And certainly browse impacts.
So regeneration analysis implicitly requires
a greater context.
Certainly if we have field crews,
such as in this picture out counting seedlings
across the landscape,
trying to best utilize that information
for the future is of high importance.
There are many barriers to native tree species regeneration.
This is just a quick lit lit review,
going over many different factors all the way
from mesophication over a long-term time period,
forest conversion development,
browse, native plant invasion, alien plant invasion,
lack of resource management plans, degradation, et cetera.
So there's numerous barriers
to native species tree regeneration.
Just starting to look at some
of the emerging research on this topic,
a recent study by Vickers et al really found a divergence
between what tree species were in the canopy
or in the overstory
compared to the seedlings in the understory.
So that if you had a canopy removal
during forest management operations,
you weren't necessarily guaranteed
to have the same forest regenerate.
So in parts of New England in this map,
the Northern hardwood regions is probably that one
that suffers the most from that kind of dynamic.
Whereas the spruce for forest
in the North display less attributes.
Further context for New England.
And that's considering the four states of Maine, Vermont,
New Hampshire and New York looking at forest inventories
that have been going on annually
since the early 2000's.
We have percentage of young forest
that's classified by inventory crews
decreasing from 9% in 2005 to about 3% in 2019.
So a somewhat steep drop
in the amount of young forest seedlings at the same time
or having a decrease, perhaps reaching a high there
in the late 2000s when our forest area maxed out
across this states.
saplings and then fairly stable with recruitment.
So there is a fair number of seedlings across landscape,
but the future forest
and where it's headed is really highly context dependent.
Relative density.
So using self thinning metrics to determine stocking
across these four States.
We had 46 million acres total in the 2000s
and most were fully stocked in terms of self thinning.
You can have a lot of small trees and be fully stocked
just as much as a lot of large trees.
So size is independent
of the stocking metrics that we're currently working on.
But we look now in the 2000s, 2010s,
we have a decrease of forest land area,
which we're seeing across most states in New England,
just a slight dip,
but we're having a rapid increase in the amount
of overstock conditions in terms of size density metrics
and a little bit of a reduction in the understocked.
So we've got fully stock forest that are starting
to level off in terms of forest area.
So potentially a lot of management decisions to be made
in the near future or for our future generation.
So a lot of the initial information was based
off the Forest Inventory and Analysis Program
as part of the USDA Forest Service.
In the following results I have later on really pertained
to this inventory where you can access this data
via the field data link.
And or if you to just have population estimates
developed for you,
you can visit this link to the right.
So prior to 2012, forest inventories just did
a stocking count of seedlings.
So if they're above a certain minimum height, over a foot,
at least a foot or so, feel crudest did account
and didn't have a DBH.
So DBH less than one inch, then they were just counted
by species, but there's many different size classes
as it were to regeneration.
So beginning in 2012,
across the 24 Northern states feel crews
during the summer started measuring seedlings
according to length classes.
So there's six different length classes,
which really refines our information on recruitment,
regeneration dynamics, and of which these merging results
I share with you, this publication GTR-148
provides a lot of the details regarding this inventory.
Some of the emerging information prior to this inventory,
this has all the information we had
about living trees in the Northeast, very useful, right?
The size classes are inches, but you get an idea
of the distribution of maples and oaks and birch and spruce
far across the Northeast.
But we didn't know about what was going on
really about the size distribution below a DBH of one inch.
But with this new inventory,
we're starting to gain a perspective of what is going on
in the understory to a higher resolution,
which also affords the opportunity
to link it to other components
of the inventory system, which I'll get to shortly.
So in context of the live trees,
what are we seeing across these four states?
What are the most populous, most abundant tree species
in the understory
for that smallest size class two to six inches?
We're talking about an overwhelming dominance
by red maple, followed up by sugar maple, ash,
balsam fur, striped maple.
And as I'll note, several times to this talk,
just because it's very abundant
in the smallest size class like striped maple
that doesn't mean the silvics or its competitive strategies,
wherever put it into the site every class,
but it is what we have to deal with.
And that's what we have in our understory currently.
Looking at a larger size class for seedlings,
so greater than five feet and less than one inch DBH,
so less smaller than sapling,
but one might term advanced tree regeneration
is heavily dominated by American beech
across this region, followed up by red maple.
And once again, we've got sugar maples,
striped maple and white ash in the running there
in the top five.
So where does that bring us to our very large trees?
So you can see the only one that sticks around
is sugar maple.
Eastern white pine by far do the land use history
and et cetera over the past a hundred plus years,
it's the dominant large tree across New England states.
Almost twice that, probably twice that of sugar maple
as far as its abundance of that size.
So where will stand development
and global change take New England seedlings next?
So right now, if we look at the population estimate
based on this inventory, our smallest seedlings number
in 170 billion, that's a lot, right?
So next largest size
are along this one can imagine a self-thinning trajectory
our largest seedlings, 31 billion.
There's tremendous amount, right?
There's a tremendous amount of regeneration.
Vast majority of it will never make it
to a very large size tree.
We started to talk about large trees.
We're talking about 54 million
and we kind of think backwards about this.
These large trees really evolve from land use conversion
et cetera, agricultural abandonment,
well over a hundred years ago.
So there was a different abundance
and diversity of tree species in the understory then.
It's probably not similar to what we have now.
So the big question is, where will these small seedlings,
these larger seedlings, where are they headed in the future?
And what will those fours look like?
Undoubtedly, they will look different than what occurred
in the past, in the 1800s or so,
as far as the understory and what developed
from agricultural abandonment, et cetera.
Another important thing that we're inventorying
is browse impact.
So we have five classes of browse impact
that we assess on our inventory plots.
Everything from very low,
plot is inside a well-maintained enclosure.
To moderate there's evidence there's browsing
on the seedlings and whatever can be eaten.
As you know, deer, they can reach up pretty high
on a browse line or very high where it's sometimes
just heavy repeated browsing, hardly anything.
And the understory it's just very, very evident
the deer are hitting a site really hard.
Looking in some of our emerging information
from that, we are working on regeneration dashboard.
We hope to release fairly soon,
but relays kind of the observations of low browse.
So you can see on the map of New England there,
the plot locations that are identified at low browse
and the estimates of seedlings by those length classes,
along with some information on our understory vegetation
to help us understand competition in the understory
for tree regeneration, along with distribution
by survey units of stand size classes.
So if you're talking about sawtimber
or pole size classes, et cetera.
If we look at our moderate and or high browse plots.
You can see distribution there in the map,
but you can see almost having in the abundance of seedlings.
So very noticeable the effect
that browse has on tree seedling abundance.
Interestingly, the impact
on understory vegetation is negligible
in terms of shrubs and grasses
and forbs and the tree abundance is about the same.
So it's the seedlings that obviously are getting hit
by browse across the region.
So, to take a step back a bit,
we've talked about the understory in detail
and we have a lot more emerging research to be done
on that and data that would be synthesized
and remeasured in the future,
but across time, here are forest inventories
around the nation,
started in the early 1900s.
Back then all you needed was a piece
of cardboard and write the word USDA on it,
the acronym and jumping in your old vehicle
and wear a suit and count trees,
but things have changed.
Back then, you're just really looking
at merchantable tree attributes.
That was the first important thing,
stocking and merchant tree attributes.
And then they started looking more
about in addition to that measuring regeneration.
And as I mentioned previously for many decades
that was just a stocking assessment.
Wasn't a lot of detail about size classes, et cetera.
Coming into the 2000s,
we started recognizing the importance of dead wood.
So he started inventorying standing dead trees
and down dead trees.
And now across the North for the past eight plus years,
we've been measuring regeneration
in a lot more detail and things like browse.
So we have a lot more data available
to us to more holistically evaluate individual tree species
in our dynamics across lands.
So looking at downed dead woods,
starting to look at the relationship
or potential relationship or interaction, et cetera,
the dynamics of live and dead and downed dead wood,
we can look at that across US
in terms of size class changes across time.
So you can get downed dead wood.
This is for the entire United States biomass change
across the decades.
So from 2000s to the 2010s
by size class of pieces.
This is downed dead wood, it's transect diameter
but you see a shift.
These biomass change across 170 plus Bailey's eco sections.
So basically ecosystems across the US forest ecosystems.
You see a shift of increasing amounts
of smaller size dead wood, and rather stable amounts
of the larger size, except for pulses that come
from obvious episodic disturbances.
But this kind of rhymes a bit
with our finding of stocking across at least the North.
And we're starting to see across the US
of highly stock stands increasing in abundance,
hence self thinning.
Hence, you're gonna see an increase
of smaller downed dead wood occurring in the ecosystems.
standing dead wood, a little bit of an increase
in the very large kind of sizes, a large amounts
and large sizes of standing dead trees, which is indicative
of episodic disturbance events,
especially in these more mature stands,
but not necessarily a shift
of any large degree across time.
Looking at live trees, you certainly see this
a bit of a shift from a decrease
in the amount of biomass change for the smallest size,
less than 27 meters and a shift to the right
for the largest size
with once again, kind of is indicative
of a maturing resource across the entire US.
Now, we think about all this in the context of regeneration.
It's interesting to see how we might combine
some of this as far as the dynamics
to really understanding what's going on.
And we're able to do that
by combining seedling information,
those size classes with live tree information,
size classes, standing dead trees
or otherwise term snags and downed dead wood.
Otherwise this term coarse woody debris
for the purposes of our inventory.
So we have a focus species here who is sugar maple,
which is in red.
Yeah, all other tree species on plots
in which have occurred.
So it's competitors across the landscape.
So we can start to see about recruitment dynamics,
et cetera, and the left side.
So the Y-axis is proportion of the Stan total,
which it occurs.
So you can see where sugar maple,
so this is stands where it is 50%
or more of the live tree basal area
certainly has more than half of the pole
and sawtimber size trees.
And it is dominating the seedlings,
the smallest size seedlings, but not necessarily recruiting
into large seedling classes nor the sapling
as much as it is dominating the smallest seedlings
and the pole and sawtimber size.
As far as downed dead wood,
there's not a lot of necessarily legacy effects
of standard development regarding
the standing dead and downed dead.
So really you see this figure
as being the relationship here between the recruitment
on the left side and the legacy effects of this species.
And in the kind of center of this figure,
you have the traditional size density kind of stalking,
kind of a assessment you're used to seeing.
How many sampling pole, sawtimber live trees
do you have for the species compared to others?
We're just bringing in the other information.
So we can like play this
looking at all basal area,
levels of basal area
that sugar maple occupies across stands,
across the entire Northern United States
by playing it as a movie here
where you have sugar maple basal area.
You can see it changing from zero to a hundred percent.
And what happens as far as changing
across the landscape in terms of this individual species?
So proportion of stand on total
and this we can assess for really any species
across landscape to understand recruitment
and understand legacy effects and competition.
Let that play one more second for you to watch.