Download How do we grow trees with today`s deer populations?

Forest Stewards Guild
Can we grow trees with today’s deer densities?
Aldo Leopold became deeply concerned with over-abundant deer in
Wisconsin in the 1940's after taking a trip to Germany in 1935 and seeing
the impacts of over-intensive game & forest management
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Why deer are a concern to forest managers and
landowners? Talk Outline: The problem!
• Forest regeneration
• Biodiversity of plants, birds, insects
• Spread of invasive species
• Deer are killing us:
• Car and motorcycle collisions
• Lyme and other tick borne diseases
• Primary effects
• Secondary effects: no child in the woods
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Bradshaw and Waller 2016
• Forest
regeneration
Sample
13,105
FIA Plots,
“Impacts of white-tailed deer
1983 to 2013. 48 Deer
on regional patterns
Module 5, Lecture 2
Management Units.
of forest tree recruitment”
Forest Ecology and
Management August 2016
Study area
(shaded)
is all of
northern Wisconsin
mixed hardwood
region but NOT
the Apostle Islands
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Variation in estimated deer densities (deer per km2)
among Deer Management Units (DMUs) from 1983 to
2011. Note the high level of variation in estimated deer
densities
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Distributions of red maple and northern white cedar sapling
numbers among stands. Frequency histograms show the
logarithm of the mean number of small saplings (+ 1) in all
stands. Note the approximately log-Normal distribution of
sapling abundances in red maple, a prolific seeder of
intermediate palatability to deer
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Distributions of northern white cedar sapling numbers among
stands. Frequency histograms show the logarithm of the
mean number of small saplings (+ 1) in all stands. Note the
highly skewed distribution in cedar (b) which is highly
palatable and susceptible to deer browse
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Palatability classes
Class 1, low: Picea spp. and Abies balsamea
Class 2, low intermediate: Acer rubrum Acer saccharum
Populus tremuloides
Class 3, high intermediate: Pinus strobus Quercus rubra
Class 4, high: Betula alleghaniensis, Tsuga canadensis,
Thuja occidentalis. High means very palatable to deer
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Forest Stewards Guild
Palatability Class 2
Can we grow trees with today’s
deer densities?
(yellow
line,
maples and aspen)
• Forest regeneration
strongly declines
depending on deer
densities 10 years
prior
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
A path analysis (statistics using partial regression
coeffiecients catching cumulative effects)
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Study conclusions:
“Deer have considerably reduced regeneration in many tree species
of intermediate palatability and eliminated it altogether at most
sites in several conifer species known to be sensitive to deer
browsing. This is highly relevant for deer management in that
stands of these conifers provide key habitats for overwintering
deer. These stands will likely disappear given this regional failure in
regeneration. These effects are not local, temporary, or restricted
to a few sensitive species. Rather, they extend across all of
northern Wisconsin, cover a 30 year period, and affect most (8 of
10) of the tree species examined. These effects have also begun to
modify the composition and structure of the mid-stories of these
forests. It will not be simple to limit or reverse these impacts…”
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Why deer are a concern to forest managers and
landowners? Talk Outline: The problem!
• Forest regeneration
• Biodiversity of plants, birds, insects
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
Impact on plants
An old-growth forest in Pennsylvania
that had been sampled in 1929. Dr.
Rooney returned in 1995 and
duplicated the sampling of 1929.
During that interval the deer
population of that area of
Pennsylvania has skyrocketed to
about the same level as southern
Wisconsin. A startling 80% of the
understory species had disappeared.
There had been 42 species and now
there were 8. Dr. Rooney attempted
to explain this disappearance by
other causes but concluded that deer
were primarily responsible.
Module 5, Lecture 1
Rooney, T.P and W.J. Dress. 1997.
Species Loss Over 66 Years in the
Ground Layer Vegetation of Heart’s
Content, an Old-Growth Forest in
Pennsylvania. Natural Areas Journal
17-297-305.
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
Impact on Birds
Deer are opportunistic feeders. The
photo on the right shows deer eating
sparrow nestlings. In a study in
Pennsylvania in 1994, intermediate
canopy nesting birds declined 37%
in abundance with a 27% drop in
species diversity at high deer
densities, similar to what we have
here in Wisconsin. This was due
References: White-tailed deerpredators of grassland birds-USGS
mostly to the change in plant life
brought on by the deer, rather than DeCalesta, D.S. 1994. Effect of White-Tailed
Deer on Songbirds Within Managed Forests
direct predation of nestlings.
in Pennsylvania. Journal of Wildlife
Management 58:711-717
Module 5, Lecture 1
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Why deer are a concern to forest managers and
landowners? Talk Outline: The problem!
• Forest regeneration
• Biodiversity of plants, birds, insects
• Spread of invasive species, and differential
browsing favors invasives over natives:
Natural Areas Journal 29(2):110-116. 2009
“Deer Facilitate Invasive Plant Success in a Pennsylvania
Forest Understory”
Tiffany M. Knight1,2 Jessica L. Dunn1 Lisa A. Smith3
JoAnn Davis4 Susan Kalisz
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Why deer are a concern to forest managers and
landowners? Talk Outline: The problem!
• Forest regeneration
• Biodiversity of plants, birds, insects
• Spread of invasive species
• Deer are killing us:
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In 2008, over one million deer collided with cars and
motorcycles in the US. The Insurance Institute for
Highway Safety stated this resulted in the death of
approximately 150 people, injuries to 29,000 others, and
an estimated $1.1 billion in vehicle damage
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Secondary effects: no child in the woods
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But wait, there’s more!
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Don’t forget Anaplasmosis, which has the same
increase over time and about half the fatality rate!
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Deer
are
killing
themselves
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Talk Outline: Solutions and ideas.
• Understanding history—how we got to where we are
• Understanding and being able to detect deer browse
and effects
• Missing evidence when deer are feeding on acorns
• Once a decade shifts due to harsh winter
• Your own exclosures, trail cams
• Getting hunters on your land
• The Quabbin experience
• The Weston experience
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Talk Outline: Solutions and ideas.
• Understanding history—how we got to where we are
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Big predators of the Northwoods
Cougar
Gray Wolf
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Dark blue areas show
20 to 67 percent
decrease in Hemlock!
Our Hemlock is disappearing!
slide from D.Mladenoff
Module 5, Lecture 2
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new habitat created
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Talk Outline: Solutions and ideas.
• Understanding history—how we got to where we are
• Understanding and being able to detect deer browse
and effects
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How do deer affect plant species?
Intense hardwood browse in
the Chippewa National Forest.
Photo by Christina Isenring
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Are trees
sensitive to deer
damage?
Study this photo for a minute.
This is called a “sandwich tree,”
in this case an eastern hemlock
in the Ottawa National Forest.
The bottom of the tree, around
the lower clipboard, is more or
less intact as it is protected
below deep snow in the winter.
The middle of the tree is gone,
eaten by deer. The top of the
tree, by the upper clipboard, is
also intact as it is around 7 feet
above ground.
Photo by Bob Wernerehl
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Are trees
sensitive to
deer damage?
Here’s another shot, this
time with Dr. Rooney beside
a balsam fir sandwich tree.
This indicates severe browse
as balsam fir is low on the
list of deer menu choices.
This tree will have a very
hard time making it to the
canopy with all this browse
holding it back.
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Browse lines are evident on
Northern White Cedar
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How do deer affect plant species?
Impacts on Reproduction.
Deer often graze off flowers & fruits first.
These are often conspicuous and exterior, they
stick out from the rest of the plant. Flowers and
fruits are, of course, vital for reproduction and
represent the next generation.
Grazed plants persist vegetatively, but often fail
to reproduce.
Effects of failed reproduction on population
growth often are delayed and obscure relative to
the more conspicuous and immediate effects of
vegetative browsing (scarce or absent seedlings).
Deer browsing can represent a threat to
population persistence even when the plants
themselves persist.
Flower top nipped off of Solomon’s Plume
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deer vs rabbit browse
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How to recognize deer browse
browsed wild sarsaparilla
Photos by Bob Wernerehl
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Look closely
to see the
slightly
ragged ends
of the stems
of the
browsed wild
sarsaparilla
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Deer Exclosures
Another way to study the effect of deer browse is through deer exclosures—
fenced areas that keep deer out. These require 8 to 10 foot high fences
maintained so that treefall doesn’t bring down the fence and let in deer. In the
Chequamegon-Nicolet National Forest at Foulds Creek, biologists erected an
exclosure more than 30 years ago (left). The other photo is of an exclosure that
has been in place for 15 years at the Dairymen’s Club of Vilas County.
Fence down the middle, deer
excluded from L-side.
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Approaches to studying deer impacts
III. Island comparisons
C. Balgooyen and Don Waller
surveyed variation across 12 locations
in the Apostle Islands and adjacent
Bayfield peninsula. They found
reductions of many species at sites
with higher deer densities, including:
mountain maple (Acer spicatum) and
sugar maple (Acer saccharum),
yellow birch (Betula allegheniensis),
mountain ash (Sorbus decora), and
Canada yew (Taxus canadensis)
(r2 = .91 !). Note that the Ojibwa
word for yew: ‘that which grows
everywhere’
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What are the long-term effects of
browsing?
If trees repeatedly fail to
reproduce, the understory
thins out. Eventually, canopy
trees that fall are not
replaced.
This produces savanna-like
conditions, and allows
invasions by ferns.
Eventually, ‘Fern Parks’
develop, as in parts of
Pennsylvania.
>20 deer / km2 for 30+ yrs
Is this the future for
Wisconsin's forests?
Allegheny plateau, PA
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Talk Outline: Solutions and ideas.
• Understanding history—how we got to where we are
• Understanding and being able to detect deer browse
and effects
• Missing evidence when deer are feeding on acorns
• Once a decade shifts due to harsh winter
• Your own exclosures, trail cams
• The Quabbin experience
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THE QUABBIN EXPERIENCE:
White-Tailed Deer Population Reduction and the Ecological
Response
Dan Clark
MA Department of Conservation and Recreation
Division of Water Supply Protection
Natural Resources Section
Quabbin Reservation
• Created in the 1930’s
• Water flows from Quabbin into Wachusett reservoir
then on to Boston
• Quabbin holds 412 billion gallons
• Treated, but unfiltered water
Quabbin Reservation
DCR owns 56,000 acres
93% forested
99% of forest is older than 50 years
59% is older than 90 years
50% of forest is hardwood
23% is softwood
27% is mixed
Deer at Quabbin
Closed to hunting from 1930’s until early 1990’s
Signs of over browsing first seen in 1946
Deer densities estimated from 1983-1992
Deer densities ranged from 45-60 deer/mi2
Petersham: 60 deer/mi2
804 deer
Forest conditions with lots of deer
Forest conditions with lots of deer
Forest conditions with lots of deer
Forest conditions with lots of deer
Mean Stem/Acre at Quabbin from 1989 - 2014
12000
11134
Stems/acre
9000
8395
8239
8031
6000
4531
4109
3372
3780
3275
3000
2389
1344
910
130
417
0
1989
Total Regen
1994
2004
Regen >4.5 Ft
2006
2009
Linear (Total Regen)
2013
2014
Linear (Regen >4.5 Ft)
Current Forest Conditions
Current Forest Conditions
Roadside breeding bird data
Towhee
Ovenbird
Yellowthroat
Chestnut
120
90
60
30
0
1988
1989
1990
1998
2006
2010
2014
Return of herbaceous plants
Brambles:
blackberry and
raspberry
Sumac
Flowers: lady
slipper
Trout lily
Trillium
Cardinal flower
Poison ivy
Ecological diversity
Grape vines
Milkweeds
Joe pye weed
Asters
Marsh marigold
Alder
Ruffed grouse &
rabbits
Conclusions
Deer densities at Quabbin substantially reduced and
maintained at much lower levels
Excellent response from the forest
Able to regenerate trees
Diversity is still lacking but moving in right direction
Increased ecosystem diversity
Herbaceous plants
Wildflowers
Bird communities
Small mammals
Recovery is relatively slow and ongoing
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Talk Outline: Solutions and ideas.
• Understanding history—how we got to where we are
• Understanding and being able to detect deer browse
and effects
• Missing evidence when deer are feeding on acorns
• Once a decade shifts due to harsh winter
• Your own exclosures, trail cams
• Getting hunters on your land
• The Quabbin experience
• Resources for quantifying deer effects
• The Weston experience
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Free
online
(downloadable
pdf
booklet),
great
resource!
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Forest Stewards Guild
Can we grow trees with today’s deer densities?
Recommendations for landowners and managers
• Understand and be able to detect deer browse and
effects
• Don’t seek evidence when deer are feeding on acorns
• Once a decade shifts due to harsh winter
• Set up your own exclosures and trail cams
• Get good hunters on your land and educate them!
• Get the public, especially mothers, on your side.
• In a “political” debate, bring the animals rights
groups in early on rather than after the fact. Know
how to respond. Be ready to handle the media.
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