Evaluating Replacement Tree Species in Black Ash Forests
Threatened by EAB and Climate Change
The Context: millions of acres and billions of trees
The Concern: threatened by EAB and climate change
The Need: adaptive strategies, including replacement trees species
Brian Palik
USDA Forest Service
Northern Research
Station
Tony D’Amato
School of Environment
and Nat. Res., Univ. of
Vermont
Robert Slesak
Minnesota Forest
Resources
Council
Christopher
Looney Dept. of Nat. Res.,
Univ. of Minnesota
Mitch Slater
USDA Forest Service
Northern Research
Station
• Black ash forests are a large
proportion of Lake States
landbase
• 440,000 ha ( 1.1 million ac) & 1
billion trees in Minnesota
• Glacial lake and outwash plains,
muck soils, impeded drainage
Black Ash in Minnesota
Why black ash forests matter:
-Timber (Forest Industry)
-Habitat (Biodiversity)
-Carbon storage (Climate Change)
-Cultural resource (Basket Making)
NMS 1
-1.5 -1.0 -0.5 0.0 0.5 1.0
NM
S 3
-1.5
-1.0
-0.5
0.0
0.5
1.0
Mountain
MapleWhite
Cedar
Balsam
Poplar
Willow
Speckled
Alder
Red MapleQuaking
Aspen
Paper
Birch
Balsam
Fir
Choke
CherryYellow
Birch
Green Ash
American
Elm
Black
Ash
Species
Bla
ck a
sh
Bal
sam
fir
Bal
sam
popla
r
Pap
er b
irch
Am
eric
an e
lm
Gre
en a
sh
Quak
ing a
spen
Red
map
le
White
ced
ar
Yello
w b
irch
No
. p
er
ha
0
100
200
300
400
500
600
700 Overstory Species
Black ash can be the dominant species in wetland forests in the north
What do we know about black ash in Minnesota
Palik, Ostry, Venette, et al FEM 2011
What do we know about black ash stand structure?
-Long-lived trees (300+ years)
-Strongly uneven-aged; recruitment peaks reflective of drought and canopy disturbance
-Overstory present during regeneration events; gap-based dynamics
But Black Ash Forests have Issues…
Including…
Emerald Ash Borer
Emerald Ash Borer is on the
doorstep of the largest
concentration of ash in the
North America
More bad news… Climate projections for northern MN
Projected habitat changes for co-occurring
tree species in Fraxinus nigra wetlands:
-Reduced habitat suitability 50% of spp.
-Neutral: 25%
-Increased: 25%
Future adapted species occur
only in low abundance in these
forests
Species
Bla
ck ash
Bals
am fi
r
Bals
am p
oplar
Paper
birch
Am
erican e
lm
Gre
en ash
Quakin
g aspen
Red m
aple
White
cedar
Yello
w b
irch
No
. p
er
ha
0
100
200
300
400
500
600
700
EAB is cold sensitive; warmer
winters > EAB survival
Species
Bla
ck a
sh
Am
eric
an e
lm
Bal
sam
fir
Bal
sam
popla
r
Mounta
in m
aple
Quak
ing a
spen
Speckl
ed a
lder
Sugar m
aple
Will
ow
No
. p
er
ha
0
200
400
600
800
1000
Wetland
Upland
Sapling layer is
mostly black
ash and alder..
Also, few trees in
the regeneration
layer:
-speckled alder
-hazel
-mountain maple
-dogwood
Sapling Species
No tree species
poised to replace
black ash….should
something bad
happen!
Even more bad news… Not a lot of advance regeneration of other species
Palik, Ostry, Venette, et al FEM 2012
Without Trees…
-Black ash wetlands get even wetter
-Sedge/shrubs dominate
-Tree establishment becomes difficult
-Loss of ecosystem function, habitat
The Concern:
There is a growing sense of
urgency among regional
organizations to find adaptation
strategies to maintain trees in
these ecosystems
The Need:
Adaptive strategies, that keep
forests on the landscape
Including evaluation of replacement tree species
0 6030 Kilometers
Large-scale manipulative experiment on Chippewa National Forest
Evaluating the Ecological Impacts of
Emerald Ash Borer in Black Ash Forests
-What are potential impacts of EAB and
associated management actions on structure
and function of black ash forests?
-Are there adaptive strategies to build site-level
resilience to EAB and climate change (i.e.,
maintain forested wetland condition)?
Brian Palik
USDA Forest Service
Northern Research Station
Tony D’Amato
School of Environment and
Nat. Res., Univ. of Vermont
Robert Slesak
Minnesota Forest
Resources Council
10
Including evaluation of replacement tree species
-Conceived by Gary Swanson (CNF) in 2009
-Developed by Palik, D’Amato, Slesak in 2010
-Harvested winter 2011-12
-Planted 2011-2012
4 treatments
1. Unharvested control
2. Clearcutting
3. Group selection
4. EAB emulation
-All treatments are 1.6 ha (4 ac);
-8 replicates of each
Examining:
-Hydrology
-Native plant communities
-Natural regeneration
-Amphibian communities
-Aquatic food webs
-Planted regeneration growth & survival
Northern Wet Ash Swamp (WFn55);
Northern Very Wet Ash Swamp (WFn64)
The Study:
Group Selection
Clearcut
Girdling
Emulates EAB
Control
Treatments
Replacement Tree Species
-12 tree species: planted F2011 &/or Sp2012
-Most present in regional ecosystem:
Red Maple*, Yellow Birch*, Eastern Larch,
Eastern Cottonwood*, Black Spruce,
Balsam Poplar, Quaking Aspen, White
Cedar, American Elm*
-Two from the next southern climate zone:
Hackberry*, Swamp White Oak*
-One exotic:
Manchurian Ash*
Northeast Asia & Japan
EAB-resistant
*Future adapted: climate and EAB
Survival by species
• Survival highest for non-native,
pathologically-limited, or out-of-
range species
• Species with high survival are
predicted climate change adapted
• Survival lowest for commonly
occurring, native species
• Species with lowest survival are
often climate change mal-adapted
(predicted)
Percent survival (Year 5)
1. American elm (74)
2. Swamp white oak (69)
3. Manchurian ash (52)
4. Hackberry (43)
5. Balsam poplar (24)
6. Red maple (23)
7. Black spruce (11)
8. Tamarack (7)
9. White cedar (6)
10. Cottonwood (4)
11. Trembling aspen (3)
12. Yellow birch (3)
Results
Looney et al. CJFR 2015
Survival: Species x Planting Season
-Higher fall survival: swamp white oak, Manchurian ash, balsam poplar
-Higher spring survival: black spruce, red maple
-Generally not a large difference between planting seasons (overly wet microsites were avoided with spring planting)
Survival: Treatment x Species (5th year)
Mean Percent Survival (+/- 95% CI)
-Survival of future-adapted species was generally lower in the clearcut
-Similar patterns of survival among control, group, girdle
Looney et al. CJFR 2015
Planted Seedling Growth (2013 to 2015)
-Both height and diameter (relative) growth increased from the control to the group selection to the girdle treatment, to the clearcut
Results Looney et al. CJFR 2017
Growth parallels gradient in LAI
Growth: Treatment x Species
-Most species had highest growth in clearcut and girdle treatments, with group selection intermediate and control lowest
Relative Diameter Growth
Results
-Replacement species growth:
-Balsam poplar highest in all treatments;
-Swamp white oak and American elm moderate in all treatments,
-Manchurian ash and hackberry low in all treatments
Looney et al. CJFR 2017
Ranking replacement species:
-Need to balance survival and growth -Shorter and longer-term perspectives -Evaluated in the context of appropriate silvicultural approach
Rank order of 5th year
survival in group selection:
1. American elm (DED tolerant)
2. Swamp white oak
3. Manchurian ash
4. Hackberry
5. Balsam poplar
6. Red maple
7. Black spruce
8. Eastern larch
9. Northern white cedar
10.Eastern cottonwood
11.Yellow birch
12.Trembling aspen
Rank order of 3 year relative
diameter growth in group selection:
1. Balsam poplar
2. Eastern larch
3. Eastern cottonwood
4. Swamp white oak
5. Red maple
6. Black spruce
7. Northern white cedar
8. American elm (DED tolerant)
9. Hackberry
10.Manchurian ash
Trembling aspen, yellow birch: survival too
low to assess growth
Shorter term?
Longer term?
Recommended
replacement species
In rank order for northern wet
forests:
1. Tamarack
2. N. white cedar
3. American elm (DED tolerant)
4. Black spruce
5. Balsam poplar
6. Yellow birch
7. Balsam fir
8. Red maple
9. Trembling aspen
10.Ash
11.Silver maple
Replacements should consider:
-Site appropriateness,
-EAB resistance
-Future climate adaptation
(swamp white oak?)
?
Summary and Recommendations
• Adaptation strategies for black ash wetlands need to consider replacement tree
species, as well as the silvicultural approaches best suited to facilitate success
• Loss of trees from EAB or preemptive clearcutting, while increasing growth of some
species, shift sites towards challenging hydrologic conditions and may limit long-
term survival
• Group selection is consistent with the ecology of these systems (gap dynamics,
uneven-aged) and has generally good seedling survival, including several future
adapted species
• Balsam poplar and swamp white oak provide a good balance of growth and survival,
particular with group selection
• Fall planting may be logistically easier, has higher survival for some species, and
about the same survival as spring planting for most species
• Pre-emptive planting (before EAB) in uncut forest of tolerant, future-adapted species
may be a viable strategy
USDA Forest
Service Northern
Research Station
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