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- Welcome, everybody.

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My name's Alex Balial.

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I'm with the FEMC.

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It's my pleasure to
introduce Katlyn Schulz,

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a graduate student at
the University of Maine.

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Katlyn will present the
effects of harvesting

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on lowland northern
white-cedar stand structure

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and composition.

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- All right, thanks for
the introduction, Alex.

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Like she said, I'm a master's student

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at the University of Maine,

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and I'm going to be presenting
on management impacts

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on sustainability of lowland
northern white-cedar.

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So to begin, northern white-cedar's

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a boreal conifer tree species

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that's distributed throughout
the northeastern United States

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and the southeastern part of Canada,

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which you can see on the map to the left.

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It's a slow-growing, shade-tolerant,

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and long-lived tree species,

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and although this tree
has a lot of economic,

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cultural, and ecological
value in the region,

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it's also one of the least
studied commercial tree species

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in North America, so that
makes any new information

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on the species really valuable.

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My master's project
will focus on the effect

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of harvesting on lowland
northern cedar stands,

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which are characterized by
wet, swamp-like environments.

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Around 70% or more of the
stands are made up of cedar,

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and the rest is a mix of
deciduous and evergreen species.

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These ecosystems are extremely sensitive

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to environmental changes,

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and they can be greatly
impacted by human activity.

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Since the early 1900s,
the cedar population

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in Maine has been steadily declining,

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and the cause has been attributed mainly

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to poor management practices
and excessive harvesting.

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Cedar is really challenging to manage,

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and even more so in
sensitive lowland ecosystems.

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One of the biggest reasons
it's challenging to manage

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has to do with all the seasonal flooding

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that occurs every spring.

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Cedar has very specific water requirements

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in order to regenerate,
and it can rot and die

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if they're exposed to too much water.

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Additionally, as a shade-tolerant species,

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cedar grows really slowly,
so its growth is suppressed

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under the canopy for many
years by its competitors.

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Finally, cedar is a preferred
winter browse species

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for forest mammals like deer and bear,

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so those that can establish

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and grow are often eaten in the winter.

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The combination of all
of these factors makes it

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extremely difficult for cedar to thrive

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after they're harvested,

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and it's causing the
population to decline.

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My study will focus on assessing
the impact of harvesting

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on two of the challenges to
cedar regeneration recruitment,

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which are in in bold.

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In order to understand
if harvesting positively

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or negatively impacts
cedar regeneration sites,

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it's equally important to
look at the impact of harvest

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on both cedar and its main competitors.

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This will help them determine
if harvesting creates

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environments that will promote
future cedar regeneration,

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or that of its competitors.

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Cedar's main competitor

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in the lowlands stands is balsam fir,

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which is an extremely common
and widespread tree in Maine,

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but it has a lot less ecological

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and economic value than cedar.

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Although it's a native tree,
it's considered to be needy

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in many core stands across Maine,

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because it's really fast-growing,

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has a lot less specific site
requirements than cedar,

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and their regeneration often
dominates the forest floor.

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The biggest problem for
lowland cedar is competition

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and canopy suppression.

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Therefore, my study is
focused on managing cedar

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in lowland stands, which
again, is challenging to do.

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Previous research conducted in upland

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and mixed stands suggests that

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partial harvesting might
be an effective treatment

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for lowland stands, because
it retains a large portion

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of adult trees dispersed
throughout the stand,

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which has proven effective
in promoting growth,

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regeneration, and recruitment.

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Therefore, the overarching
goals of my study are

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to determine the conditions
that are associated

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with cedar and fir
regeneration in lowland stands,

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and then increase our understanding

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of how partial harvesting
impacts structure, composition,

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regeneration, and
associated micro-climates

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in the lowland stands to determine

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proper management procedure.

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For this study, three lowland cedar sites

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throughout Maine were selected,
which you can see labeled

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as stars on the map to the left.

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All three of the sites had a history

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of unspecified partial harvesting
prior to the mid 1900s,

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with no known harvesting since then.

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The middle image is of one of our sites,

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so each of our sites
had one treated stand,

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and around one to three control stands,

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and within each of those stands were

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around four to five
fixed-radius plots that we took

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measurements in, and then
two to three mil-plots

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within those spots.

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To achieve the first objective,

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a partial harvesting treatment
was applied to one stand

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in each of the three lowland cedar sites.

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The two images to the left
show the density of the stand

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before and after a harvest,

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and it was treated by an
irregular shelter with treatment

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that had a target removal of
40% stand basal area removal

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of trees over 4.5 inches in
diameter at breast height.

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The harvest was meant to thin the stand,

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capture mortality, improve the growth

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of the best cedar trees, and improve

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overall stand vigor and
quality, while maintaining

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structural complexity,
and opening the cedar,

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or opening the canopy
for cedar regenerations.

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Next, we took measurements,
and conducted them

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on three sites to determine the conditions

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that are associated with
cedar regeneration and fir,

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as well as to assess
the impact of harvesting

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on those conditions, and the composition

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and structure of the stand.

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Pre-harvest measurements were conducted

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the summer before the harvest,

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which took place in the winter,

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and then post-harvest
measurements were conducted

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the summer after the harvest.

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My thesis is part of
multiple ongoing projects

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in which all of these measurements

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on the site were assessed.

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However, today I will be
reporting some preliminary results

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from the first stage of
analysis for the measurements

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that are related to my
thesis, and these are in bold.

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So now we're gonna move on to the results

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of the pre-harvest
conditions of the stands.

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So before the harvest took place,

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trees per hectare was
calculated to determine

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the species composition of understory,

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which is the seedling and sapling layer,

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and then the overstory,
which is the tree layer.

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For this graph, trees per
hectare is on the Y axis,

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and size, class, and species is on the X.

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It was found that in a
majority of the stands,

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fir dominated the understory.

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In both the understory and the overstory,

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all the other tree species,

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like spruce and birch were
minor components of the stand.

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It was only in the overstory
that cedar composed

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a majority of the species composition,

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and this is what classified
these stands as cedar swamps.

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Oop.

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This finding directly
contradicts the findings

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of similar cedar studies in the region,

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which found that cedar
dominated the overstory

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and the seedling layer,

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while fir dominated the sapling layer.

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In these studies, a recruitment
bottleneck was observed

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between the cedar seedling
and sapling class,

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and it was determined that
their growth was limited

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by things such as light availability,

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browsing, or competition.

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However, for my study, the
limited cedar regeneration

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in the seedling layer
suggests that regeneration

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and establishment is being limited

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by a lack of suitable microsites,

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rather than a recruitment bottleneck.

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One potential explanation for the lack

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of suitable microsites
for cedar could be related

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to micro-topography, or
the topographic variability

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of the soil surface.

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For this study, we identified
three different types

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of micro-topographic positions,

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mounds, which are the raised areas,

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flats, which are the level areas,

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and then pits, which are the
sunken areas in the ground.

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After averaging all the sites together,

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we found that mounds consisted around 33%

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of the landscape, flats around
48, and pits around 18%.

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In the wetland conditions
of the lowland cedar stands,

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mounds are thought to
be particularly valuable

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in landscapes, because they're
significantly less saturated

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than flats and pits,
and this helps to reduce

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mortality from flooding.

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Therefore, we expect to find both cedar

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and fir positively associated with mounds,

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and negatively associated with flats.

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To assess the association
of fir and cedar abundance

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with positions, the occurrence
of a pit, mound, or flat

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on a landscape was compared
with the actual positions

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of cedar and fir seedlings
found on a flat level

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for each management unit.

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This was done using a Chi-squared test,

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and standard residuals and P values

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that were generated were
average to the stand,

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site, and then study level.

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Results were recorded at the site level,

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and then across all sites.

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This figure on the slide is a heat map

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that helps to visualize the association

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of seedling abundance with positions.

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Micro-topographic
position is on the Y axis,

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and then three different
study sites are on the X,

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as well as the division between
fir and cedar seedlings.

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Finally, the standard residuals,

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which are denoted by the
different colors, indicate

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if the seedlings are associated

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with a certain position or not.

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Green indicates that more
seedlings would be found

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more often than expected by chance,

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whereas red indicates the opposite.

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The white color indicates
that seedlings are found

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as often as expected
on a certain position,

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and then stars in the
right-hand corner indicate

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if results were statistically significant.

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What we found was different
than when we expected.

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Fir seedling abundance was found to have

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a greater association
with mounds than cedar,

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which you can see by the two dark squares

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with stars on the left.

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This is compared with cedar,
which has a lesser association

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with mounds, which you can see

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by the two light green
squares and only one star.

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This finding directly
contrasted many of the studies

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that have found a strong
association of cedar with mounds.

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One explanation could be
that fir is dominating,

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and out-competing cedar on the mounds.

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Additionally, mounds consisted
of an average of only 33%

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of the landscape, but other
studies have suggested

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that cedar regeneration
required at least 70%

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of the landscape to be composed of mounds

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in order for cedar to avoid
interest-specific competition.

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So next we'll move on to pre
versus post-harvest conditions

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of the overstory.

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So in order to determine if
partial harvesting impacted

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stands' structural
attributes and regeneration,

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pre and post-harvest conditions

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for eight variables were
compared and tested,

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using linear mixed effects models,

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using a random effect for plot

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within each treated management in it.

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We calculated the difference

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between pre and post harvest
variables at the plot level,

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and then determined if the difference was

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significantly different than zero.

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So for these next few graphs,

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the pre-harvest conditions will be

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on the left side of the graph,

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and the post-harvest conditions
will be on the right.

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This first graph involves basal area,

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which was significantly
reduced after the harvest.

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00:11:17,570 --> 00:11:20,420
The second graph reveals
a significant decrease

258
00:11:20,420 --> 00:11:23,210
in canopy cover, around 20%,

259
00:11:23,210 --> 00:11:25,750
from pre-harvest to
post-harvest conditions.

260
00:11:25,750 --> 00:11:28,040
However, you can see
that, while the reduction

261
00:11:28,040 --> 00:11:31,330
in basal area indicates
that the stand was thinned,

262
00:11:31,330 --> 00:11:34,940
and the canopy was open, it
wasn't really opened that much.

263
00:11:34,940 --> 00:11:38,850
Canopy cover is still around
70%, and this still mimics

264
00:11:38,850 --> 00:11:41,670
the relatively shaded
conditions that cedar prefers,

265
00:11:41,670 --> 00:11:42,720
so it's a good thing.

266
00:11:43,970 --> 00:11:46,720
This next graph looks at the
change in trees per hectare

267
00:11:46,720 --> 00:11:48,370
from pre to post-harvest.

268
00:11:48,370 --> 00:11:51,230
This graph is divided by
species, with cedar on the left

269
00:11:51,230 --> 00:11:54,120
in red, and fir on the right in blue.

270
00:11:54,120 --> 00:11:55,700
As we learned from the previous graphs,

271
00:11:55,700 --> 00:11:57,850
the treatments resulted
in the overstory being

272
00:11:57,850 --> 00:11:59,600
significantly thinned.

273
00:11:59,600 --> 00:12:01,020
However, even though it was thin,

274
00:12:01,020 --> 00:12:04,010
there was not significant
declines in cedar or fir,

275
00:12:04,010 --> 00:12:07,060
or at least consistently across all plots.

276
00:12:07,060 --> 00:12:08,380
This means that our objective,

277
00:12:08,380 --> 00:12:10,250
which was to thin the stand while opening

278
00:12:10,250 --> 00:12:12,740
the canopy proceeded regeneration,

279
00:12:12,740 --> 00:12:15,290
and maintaining structural
complexity was achieved.

280
00:12:17,210 --> 00:12:19,977
So next we'll move on to pre
versus post-harvest conditions

281
00:12:19,977 --> 00:12:21,920
in the understory.

282
00:12:21,920 --> 00:12:24,277
So in assessing how
understory conditions changed

283
00:12:24,277 --> 00:12:27,510
from pre to post-harvest, we
were able to better assess

284
00:12:27,510 --> 00:12:29,420
the suitable micro-site conditions

285
00:12:29,420 --> 00:12:33,310
for cedar or fir where either
increased or decreased.

286
00:12:33,310 --> 00:12:35,980
The first graph deals
with coarse, woody debris.

287
00:12:35,980 --> 00:12:39,170
The panel on the left shows
a significant increase

288
00:12:39,170 --> 00:12:41,840
in coarse, woody debris
and decay class one,

289
00:12:41,840 --> 00:12:45,060
which is usually newly-cut wood

290
00:12:45,060 --> 00:12:47,150
that hasn't started to decay yet,

291
00:12:47,150 --> 00:12:49,970
and this is likely driven by
the presence of new stumps.

292
00:12:49,970 --> 00:12:51,560
However, interestingly enough,

293
00:12:51,560 --> 00:12:53,960
after we corrected for
multiple comparisons,

294
00:12:53,960 --> 00:12:55,340
we found that the difference was not

295
00:12:55,340 --> 00:12:56,723
statistically significant.

296
00:12:57,730 --> 00:13:00,260
This is because a majority
of the stands experience

297
00:13:00,260 --> 00:13:03,000
little to no change in wood
volume after the harvest,

298
00:13:03,000 --> 00:13:05,530
which you can see on a
histogram to the left.

299
00:13:05,530 --> 00:13:07,574
The reason why the
previous graph seemed to be

300
00:13:07,574 --> 00:13:10,870
statistically different was
because some plots were in areas

301
00:13:10,870 --> 00:13:13,480
that were impacted by the
harvest, and some are not,

302
00:13:13,480 --> 00:13:15,793
and we're gonna have to
analyze this further.

303
00:13:16,970 --> 00:13:20,130
Coarse, woody debris in decay
classes four to five were not

304
00:13:20,130 --> 00:13:22,180
significantly increased.

305
00:13:22,180 --> 00:13:24,610
The retention, of course,
woody degree can increase

306
00:13:24,610 --> 00:13:26,530
micro-topographic variability,

307
00:13:26,530 --> 00:13:29,470
and as wood progresses
into higher decay classes

308
00:13:29,470 --> 00:13:33,200
like four and five, it
retains levels of moisture

309
00:13:33,200 --> 00:13:36,850
and temperature that are
suitable for cedar regeneration.

310
00:13:36,850 --> 00:13:38,250
For the next graph, you can see that

311
00:13:38,250 --> 00:13:40,680
the percent of mounds did
not significantly alter

312
00:13:40,680 --> 00:13:43,060
after the harvest, which is also good.

313
00:13:43,060 --> 00:13:43,990
There was a concern that

314
00:13:43,990 --> 00:13:46,550
the mechanized harvesters
could cause damage

315
00:13:46,550 --> 00:13:49,670
to micro-topography within a stand,

316
00:13:49,670 --> 00:13:51,960
and this reduced the number
of seedlings that regenerate

317
00:13:51,960 --> 00:13:54,780
and survive each year,
but this didn't happen.

318
00:13:54,780 --> 00:13:56,470
Finally, with this last graph,

319
00:13:56,470 --> 00:13:58,190
you can see that the trees per hectare

320
00:13:58,190 --> 00:14:01,810
of seedling, of cedar and
balsam fir seedlings were not

321
00:14:01,810 --> 00:14:04,290
significantly changed by the harvest.

322
00:14:04,290 --> 00:14:05,600
There was initially a concern

323
00:14:05,600 --> 00:14:07,210
that cedar ceilings might be damaged

324
00:14:07,210 --> 00:14:10,100
by harvesting equipment,
but these results indicate

325
00:14:10,100 --> 00:14:12,260
that they were not, which is also good.

326
00:14:12,260 --> 00:14:15,000
And also just to clarify,
we didn't expect to see

327
00:14:15,000 --> 00:14:16,936
an increase in cedar regeneration.

328
00:14:16,936 --> 00:14:20,500
There was only a year in
between the survey periods,

329
00:14:20,500 --> 00:14:23,370
and that's not long enough
to see if there was an effect

330
00:14:23,370 --> 00:14:25,920
on regeneration and
recruitment due to the harvest.

331
00:14:27,000 --> 00:14:29,550
So what does all of this mean?

332
00:14:29,550 --> 00:14:33,920
So our results show us that
stands are dominated by fir

333
00:14:33,920 --> 00:14:36,850
in the understory, and
cedar in the overstory,

334
00:14:36,850 --> 00:14:39,650
which is different than a lot
of the stands in the area.

335
00:14:40,500 --> 00:14:43,270
The conditions of the stand
may not currently support

336
00:14:43,270 --> 00:14:45,200
cedar regeneration and recruitment.

337
00:14:45,200 --> 00:14:46,220
This could partially be due

338
00:14:46,220 --> 00:14:49,210
to micro-topographic variability.

339
00:14:49,210 --> 00:14:50,719
And then our treatment objective,

340
00:14:50,719 --> 00:14:53,301
which was to thin the stands,

341
00:14:53,301 --> 00:14:56,483
while maintaining structural
complexity was achieved.

342
00:14:57,790 --> 00:15:02,320
And then during the harvest,
it did not significantly alter

343
00:15:02,320 --> 00:15:04,470
things that support cedar regeneration,

344
00:15:04,470 --> 00:15:06,680
like coarse, woody debris,
the percent of mounds,

345
00:15:06,680 --> 00:15:09,470
or seedling density in the understory.

346
00:15:09,470 --> 00:15:12,590
So we can use all of this to come up

347
00:15:12,590 --> 00:15:15,460
with some implications for management.

348
00:15:15,460 --> 00:15:20,460
So we recommend that the
micro-topographic variability

349
00:15:20,830 --> 00:15:22,757
and volume of coarse,
woody debris is increased

350
00:15:22,757 --> 00:15:24,650
after a harvest.

351
00:15:24,650 --> 00:15:27,260
That can be done by
leaving the wood and logs

352
00:15:27,260 --> 00:15:29,713
generated from harvest on the site.

353
00:15:29,713 --> 00:15:33,410
We also recommend using a
minimum number of skid trails

354
00:15:33,410 --> 00:15:37,610
to not damage
micro-topographic conditions.

355
00:15:39,010 --> 00:15:42,116
And then all of this will
help us to create guidelines

356
00:15:42,116 --> 00:15:46,563
for lowland cedar stand
management in the future.

357
00:15:46,563 --> 00:15:50,853
So a big thank you to my two advisers,

358
00:15:52,930 --> 00:15:55,630
Jeanette Allogio, who
helped with data analysis,

359
00:15:55,630 --> 00:15:58,301
field crew, who helped me
collect data for this project,

360
00:15:58,301 --> 00:16:00,663
and then my sponsors
and committee members.

361
00:16:02,220 --> 00:16:03,990
So that's my presentation.

362
00:16:03,990 --> 00:16:05,793
Does anyone have any questions?

363
00:16:07,478 --> 00:16:09,633
- [Participant] I have a question.

364
00:16:09,633 --> 00:16:12,050
I unfortunately came in just a little bit

365
00:16:12,050 --> 00:16:13,797
after this started.

366
00:16:13,797 --> 00:16:17,022
I'm curious, how long are
you planning on continuing

367
00:16:17,022 --> 00:16:19,923
the observational component of this study?

368
00:16:20,940 --> 00:16:22,770
- Yeah, that's a good question.

369
00:16:22,770 --> 00:16:26,450
So this study has been going
on for a couple of years,

370
00:16:26,450 --> 00:16:29,775
and it will continue to go
on after my master's project.

371
00:16:29,775 --> 00:16:34,775
So we have, it should go back.

372
00:16:36,460 --> 00:16:38,990
I can, first up, oh, there we go.

373
00:16:38,990 --> 00:16:43,000
We have control stands and treated stands,

374
00:16:43,000 --> 00:16:46,063
and so the treated stands will,

375
00:16:47,740 --> 00:16:52,740
our treated stands will be
compared to our control stands,

376
00:16:53,060 --> 00:16:55,502
I think a couple of years down the line.

377
00:16:55,502 --> 00:16:57,470
Yeah.

378
00:16:57,470 --> 00:16:59,570
- [Participant] And then
how long would it take

379
00:16:59,570 --> 00:17:02,610
to actually determine the effect

380
00:17:02,610 --> 00:17:06,360
on population of more mature trees?

381
00:17:06,360 --> 00:17:09,223
Just, I don't know the
biology of the species.

382
00:17:12,030 --> 00:17:17,030
- Well, part of our goal was with

383
00:17:18,900 --> 00:17:21,920
like, these treatments was
to like thin the stand,

384
00:17:21,920 --> 00:17:25,480
and improve the growth
of current cedar trees,

385
00:17:25,480 --> 00:17:30,100
so I think the plan for
this study is to go back in,

386
00:17:30,100 --> 00:17:31,640
like, in another five years,

387
00:17:31,640 --> 00:17:35,010
and assess the conditions
of the current trees,

388
00:17:35,010 --> 00:17:37,680
and then see if there have been like,

389
00:17:37,680 --> 00:17:41,070
regeneration, or proven
effects of the harvest.

390
00:17:41,070 --> 00:17:44,620
- We've got a question in
the chat, a couple, actually.

391
00:17:44,620 --> 00:17:48,100
The first, Sean Hagan says, asks,

392
00:17:48,100 --> 00:17:50,160
do you think tipping the harvested trees

393
00:17:50,160 --> 00:17:51,927
prior to cutting wood
would enhance the pit

394
00:17:51,927 --> 00:17:54,138
and mound levels post harvest,

395
00:17:54,138 --> 00:17:56,823
thus enhancing cedar regeneration?

396
00:17:57,830 --> 00:17:59,172
- That could be.

397
00:17:59,172 --> 00:18:02,740
That wasn't like, a goal of our study,

398
00:18:02,740 --> 00:18:04,940
or something that we tried to implement,

399
00:18:04,940 --> 00:18:07,030
but I've definitely
taken a couple of classes

400
00:18:07,030 --> 00:18:10,890
that have suggested that, you know, like,

401
00:18:10,890 --> 00:18:13,360
like, small gaps that are
created by tree tipping can be

402
00:18:13,360 --> 00:18:15,290
suitable for regeneration.

403
00:18:15,290 --> 00:18:18,378
We've also seen like,
out in the field, like,

404
00:18:18,378 --> 00:18:21,930
like, the mounds that are
created by tipped trees,

405
00:18:21,930 --> 00:18:24,820
like, a lot of cedars like
to establish on those mounDs,

406
00:18:24,820 --> 00:18:26,230
so that could be a possibility,

407
00:18:26,230 --> 00:18:27,760
and something to look in to.

408
00:18:27,760 --> 00:18:30,860
- And then sort of an
addition to that question,

409
00:18:30,860 --> 00:18:33,840
Rick Morals asked if there's an assessment

410
00:18:33,840 --> 00:18:37,410
of blow-downs post-harvest,

411
00:18:37,410 --> 00:18:41,980
or if there's any plan to
measure that over time?

412
00:18:41,980 --> 00:18:43,453
- I do not believe so.

413
00:18:45,510 --> 00:18:48,620
Yeah, if anyone has any
additional questions,

414
00:18:48,620 --> 00:18:52,410
it can show my email down here.

415
00:18:52,410 --> 00:18:54,023
katlynschultz@maine.edu.