Climate change impacts and forest management

Climate change
impacts and forest
management
Jana Albers, DNR

Climate change in the past
Anticipated climate changes for Mn
Adding other forest health stressors
“Houston, we have a problem.”
Forest management adapts

Climate change in the past
• Four forested provinces
made up of many types of
forest communities at the
present time.
• Forested communities are
literally “living on the edge” of
the prairie.
• The configuration of forest
and prairie/forest border was
not always like this.

Evidence of climate change in the past
Sequence of major vegetation types in MN from 11,000 years ago to the present.

• Forest communities are
reshaping themselves all
the time.
• Even very “recent”
movements of tree
species show evidence of
a changing climate.
Duration of pine forests in MN
Pollen records show years of
continual occupancy of pine
communities from the present
looking backwards to the last
glaciation.
Almendinger, 2003

Anticipated climate changes for Mn
• Increased levels of CO2 and O3 in atmosphere.
• Warming temperatures.
In winter, minimum temps will be warmer.
Growing season will be longer.
• Drier weather during the growing season.
• Relative humidity peaks higher in summer.
• More wind storms and thunderstorms.
More large-scale blow-down events.
Less percolation of rain water into soil.
Lee Frelich, U Mn

Possible changes to growing conditions: 2095
Climate projections
for high emission
scenario by 2095.
Union of Concerned Scientists.

Future climate
analogs for Mn
landscapes 50
years into the
future
Galatowitsch, 2009

A schematic depicting the possible dynamics of climate change
Impacts on
forests
Frelich & Reich, 2009

Tree species maladapted to the future climate will experience
decreases in abundance and distribution. Other species will
benefit from climate change. Some may be neutral.
The USFS has developed the Tree
Atlas showing where climate
change is likely to have effects for
the 130+ tree species in the NE
USA. Based on FIA plots.
In MN, 12 of 22 forest species will
have hotspots of change where
the tree populations are likely to
diminish. Iverson, 2007
White spruce
Hotspots are hatched polygons.
http://www.nrs.fs.fed.us/atlas/tree/tree_atlas.html

Evidence of tree migration
• Using FIA data, researchers
found that 11 of 15 northern
tree species are moving
northwards, from 20 to 100
km/ century. Woodall, 2009
Fast paced: basswood, s maple, yel
birch, n r oak, bl ash and bt aspen
Slow paced: tam, r pine, w pine and
nw cedar,
Static: balsam fir, bl spruce, w pine,
q aspen BAM and p birch
Based on the centers of tree biomass
(red) and seedling abundance (blue) for
each tree species.
Tree biomass
Seedling counts
Note: The estimated speed of tree
migration in post-glacial times was
50 km/ century.
Based on comparison of where trees
and seedlings at each latitude class.

Implications for tree species
• The prairie/ forest border will shift
north and east.
• The range of boreal species will shift
northeast.
• Red and white pines will hold their
own or do better.
• Northern hardwoods will expand. Red
maple will become very
abundant. Sugar maple and red
oaks will increase.
• Birch will rapidly decline; aspen may
slowly decline.
• Central hardwoods will increase but
need connectivity.
Iverson, Frelich, White
Lose acreage:
Quaking aspen
Paper birch
Balsam fir
Black ash
Black spruce
Balm of gilead
Tamarack
Jack pine
White cedar
Mt. maple
Gain acreage:
Bur oak
E. red cedar
Cottonwood
Black walnut
Hackberry
N. red oak
White oak
Honey locust
Silver maple
Boxelder

Climate change is likely to reinforce the deleterious effects
of other forest organisms and processes
?
Frelich & Reich, 2009

Effects of deer and earthworms will be accelerated by climate change.
Deer, with populations 2 to 20 times
higher than historical levels, browse
on herbs and tree seedlings.
Currently, they cause the loss of
48-81% of native plant species.
Rooney, 2011
Earthworms consume the duff which
leads to exposed soil, soil
compaction, runoff, droughtier soils,
changed nutrient cycles and likely
incursion of invasive plants.
Where deer and worms occur
together, they cause a major
transformation of the forest.
Frelich, 2011

Exotic, invasive plants:
• Their effects will be on a species-by-species basis
affecting biodiversity, shading, nutrient cycling, etc.
• As climate change heats up, likely to see:
establishment of more inv plant species,
altered range/distribution of these plants,
altered effectiveness of control strategies.
• Their effects will reinforce warming impacts.

Wildfires: Climate change will likely create
a fire-prone environment with more fuels
and more lightning strikes.
• On average, 14% of all standing
trees are dead (snags). NRS 2008
• With anticipated impacts of climate
change, the number of snags is likely
to increase, fueling future wildfires.

Blowdown:
• More frequent and more serious
storms (derechos) in northern MN
are expected.
• In the last 20 years, we’ve
exceeded a millenium’s worth of
blowdown acres in MN.
Almendinger

Insects and pathogens (native and exotic):
Even a modest climate change will have rapid
impacts on the distribution and abundance of
many forest insects and pathogens because of their
short life cycles, mobility, reproductive potential
and physiological sensitivity to temperature.
Ayres, 2007
Climate change could
• Directly affect the development and survival
of insects and pathogens.
• Alter the abundance of their natural enemies
and competitors.
• Alter host tree physiology or defenses.

Examples of impacts of climate change on insects
• Reduced overwintering mortality from cold weather events.
• Faster development/ more generations per season due to
warmer and longer summers.
Ips pine bark beetles could move from
2 generations per year to 3 gens/yr.
in central and northern MN.
• Disrupt the phenological synchrony between insects and their
natural enemies.
Population increases of larch casebearer are
thought to be caused by warmer temperatures
that favor the defoliator over its parasites.

Examples of impacts of climate change on insects
Insects and pathogens may
move/migrate and establish
new ranges as climate
becomes warmer
• As the mountain pine
beetles become
established in boreal
jack pines, they might
move east through
Canada, into
Minnesota.
• 2°C rise allows
expansion about 360
miles north.
Current
locations of
mountain
pine
beetles
Jack pine
Mountain pine beetle

Changed tree physiology and defenses:
As trees become stressed by drought, changes in tree chemistry
can occur. Certain pests, called “opportunistic pests”, key in on
these stress-related chemicals and successfully attack and kill the
stressed trees.
Stressed
trees
Energy
depletion
Site, Age,
Defoliation,
Drought,
Wound,
Construction
+
Opportunistic
Phloem miners
pests
Armillaria
Dead trees

Examples of tree species that have opportunistic pests
• Pines, tamarack,
oaks, birches,
aspen, etc.
• Armillaria root
disease can kill
stressed trees.
Red pine
Bark beetles
• Persistent
outbreaks of
opportunists
will be the
bellwethers of
climate change.
Northern red oak
Two-lined chestnut borers
http://www.nrs.fs.fed.us/atlas/tree/tree_atlas.html

Multiple agents will reinforce
the impact of global warming
on forests.
• In the short-term, weather
changes will allow
opportunistic pests and
abiotic declines to accelerate
the demise of tree species no
longer suited to their current
sites. They will lose
abundance and acreage.
• Other tree species will
migrate into MN or existing
species will become more
prevalent as their range
expands. They will gain
abundance and acreage.
Implications of climate change
Lose acreage:
Quaking aspen
Paper birch
Balsam fir
Black ash
Black spruce
Balm of gilead
Tamarack
Gain acreage:
Jack pine
Bur oak
White cedar
E. red cedar
Mt. maple
Cottonwood
Black walnut
Hackberry
N. red oak
White oak
Honey locust
Silver maple
Boxelder

“Houston, we have a problem.”
Expectations: Forests are being viewed as essential for climate
change mitigation via carbon sequestration and biomass production
on a global scale.
Fears: Will there be so many deleterious changes to forests in a very
short time that forests cannot sustain themselves?
Human abilities and capacities: What about forest management?
Are old goals and schemes irrelevant? How do we “hit” multiple
moving targets involved with climate change? When and where do
we start?

Forest management adapts
• Continue to use existing and proven management techniques.
These keep our trees and native plant communities vigorous,
productive and resilient to adverse changes.
D’Amato
• Just like the trees in the forest adapting to the effects of climate
change, foresters must adapt management strategies to new and
anticipated conditions.
Climate change and forests
of the future: Managing in
the face of uncertainty.
Millar, Stephenson and Stephens

Adaptation strategies defined
Millar, Frelich, D’Amato, DNR, etc
Resistance = help species/ecosystems
to remain unchanged in the face of
climate change.
Resilience = increase the abilities of
species/ecosystems to absorb or adapt
to effects of climate change.
Facilitation = actively manage to help
the ecosystem adapt toward a
predicted direction of climate change.

Resistance = defend high-risk or high-value resources
against change. “Homeland security approach”
• Costly; direct at critically endangered
resources; effective for a short time.
• More effective now rather than later.
• Allows NP Communities to persist until
other adaptations become necessary.
• Prevent or reduce other external forest
health stressors: deer, invasive pests,
invasive plants, earthworms.
• Limit size of wildfires; create fire breaks.
• Use thinning to control stand density so
trees can survive drought.
• Use ERF to buildup stored “carbon”.

Resilience = increase the abilities of species/ ecosystems to
absorb or adapt to effects of climate change by
building stand and ecosystem complexity.
“Health care approach”
• Will work as an interim measure or
where uncertainty is high.
• Increase species diversity.
• Increase age diversity.
• Increase genetic diversity by
planting “southern” seed
sources.
• Move towards uneven-aged mgt. or
multi-age stands.
• Prevent or reduce external stressors.
• Preserve buffers around reserves.
• Build the up the seed bank.
Seed
zones

Facilitation = actively manage to help the ecosystem adapt
towards a predicted direction of climate change.
“Humble helper approach”
• We have limited capacity to understand it all.
• Will work for the largest magnitudes of climate
change.
• Risky to implement now because we aren’t
sure how climate change will actually proceed.
• Establish travel corridors in expected direction
of species change/ migration.
• Establish transitional refugia.
• Assisted migration and colonization of species
esp. oaks and other large-seeded trees.
• Anticipate and plan for the risks & losses:
large-scale fires, pest outbreaks, declines, etc.
• Continue to prevent or reduce impacts of nonclimate
tree stressors.

Continue to use existing and proven management techniques.
These keep our trees and native plant communities vigorous,
productive and resilient to adverse changes.
Build in “response diversity”. Manage for high tree species
diversity at the stand and landscape level so that another species
can fill the vacated niche of species that disappears.
D’Amato
• Build structural complexity:
Promote age class diversity;
at least 2 age classes.
Increase reliance on uneven-aged
management.
• Build compositional complexity:
Use new species mixes.
Increase species redundancy by
introducing species over a
wide range of environments.

• Trees and their forest communities
have survived large-scale tree migration
events in the past and changes in the
location of the prairie/ forest border.
• I believe that new forest communities
will emerge along with new disturbance
regimes that will maintain them.

Any questions?

DNR Forest Health Unit
Val Cervenka
FH Coordinator
651 259-5296
Susan Burks
Invasive Spp Coord.
651-259-5251
Jana Albers
NW FH Spec.
218 327-4234
Mike Albers
NE FH Spec.
218 327-4115
Ryan Blaedow
Central FH Spec.
651-259-5821

Feedback on
results of
adaptive
management
strategies will be
provided by
monitoring.

Examples of maladapted trees experiencing stress from
abiotic factors
• Adverse environmental factors add up to cause vigor
problems.
• No pests involved, at least, initially.
• Trees with existing declines may be that much more
vulnerable to the effects of climate change.
Birch decline
Ash decline
Paper birch
Black ash

A. Because most forest pests are sensitive
to temperature, even modest warming
could speed up their metabolism
requiring more food,
increasing mobility & distribution,
increasing reproduction.
B. Deer, invasive plants and earthworms
cause damage to native flora, soil
structure and nutrient cycling. Their
effects by will be accelerated.
C. Trees maladapted to their existing sites
will become more and more drought
stressed. Conversely, some species will
benefit, by gaining abundance and/or
distribution. Others may be unaffected.