The Long Game: Using Forest Regeneration as a Tool for

Climate Change Adaptation John Pedlar and Dan McKenney

Canadian Forest Service, Natural Resources Canada CIF-IFC 2018 National Conference, Sept. 17-20, Grande Prairie, AB

Projected Climate Change in Canada - Mean Annual Temperature -

CanESM2, RCP 4.5 (2071-2100 minus 1971-2000)

CanESM2, RCP 8.5 (2071-2100 minus 1971-2000)

Projected Climate Change in Canada - Annual Precipitation -

CanESM2, RCP 4.5 (2071-2100 minus 1971-2000)

CanESM2, RCP 8.5 (2071-2100 minus 1971-2000)

Projected Climate Change in Canada - Climate Moisture Index -

CanESM2, RCP 4.5 (2071-2100 minus 1971-2000)

CanESM2, RCP 8.5 (2071-2100 minus 1971-2000)

<-200 mm-150 - -200-100 - -150-60 - -100-40 - -60-30 - -40-20 - -30-10 - -20-1 - -10

Temperature

CO2 fertilization

Drought

Fire

Insects & diseases

Direct Impacts Indirect Impacts

Wind

Forest productivity, composition, structure, and function

Climate Change Adaptation

“Adjustments in natural or human systems in response to actual or expected climate change impacts that moderate harmful outcomes or promote beneficial ones.”

(Adapted from Gauthier et al. 2014)

§  Some examples (from Gauthier et al., 2014): §  Employ heightened fire suppression efforts;

§  Actively manage forest pests;

§  Generate heterogeneity in forest structure, composition, and age-classes;

§  Use pre-commercial thinning to reduce drought impacts and increase resource availability;

§  Reduce rotation ages;

§  Employ regeneration techniques that promote climatically suitable populations and/or species;

§  Use prescribed burning to reduce risks related to fire and/or insect outbreaks;

§  Employ vegetation control techniques to offset drought impacts in early stand development;

§  Minimize fragmentation of habitat and maintain connectivity;

Gauthier et al. 2014. Climate change vulnerability and adaptation in the managed Canadian boreal forest. Environ. Rev. 22: 256–285.

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Movement of Regenerative Materials Under Climate Change

7

Range Position

Assisted Gene Flow

Assisted Range Expansion

Intercontinental Movements

Movement Distance

Within Population

Within Range

Near Range

Long Range

Sho

rt-te

rm R

isk

Natural/Local Regen

No Movement

Long-term R

isk?

0

0

“Designer Ecosystems” Genetically Modified Organisms

Natural/Local Regeneration (i.e., Do Nothing)

§  Trees will exhibit phenotypic, genetic, and migratory responses to CC in absence of human intervention

§  Phenotypic responses will depend on degree of plasticity in gene expression

§  Natural selection will be facilitated by high genetic diversity, but slowed by long generation times of trees

§  Tree migration rates are at least an order of magnitude slower than CC

§  Generally thought that natural tree responses will lag significantly behind CC

8

Source: Becklin, K. M., et al. (2016). Examining plant physiological responses to climate change through an evolutionary lens. Plant physiology, 172(2), 635-649.

Range Position Considerations

§  Using provenance data, we showed that tree populations often exhibit an optimum temperature for growth

§  This optimum was located in the southern portion of the range

§  Pattern consistent across 5 northern conifers: black spruce, jack pine, lodgepole pine, white pine, scots pine

§  Recently published these findings: Pedlar, J. H., & McKenney, D. W. (2017). Assessing the

anticipated growth response of northern conifer populations to a warming climate. Scientific Reports, 7.

9

Jack Pine Response Curves

Jack Pine Range

Optimal Temperature

+20 0 -20 -40 -60 -80

Magnitude of Climate Change (oC)

0 1 2 3 4 5 6 7 8

Ran

ge P

osi

tion

10

20

30

40

50

60

70

80

90

-80 -60 -40 -20 0 20

Ran

ge P

ositi

on

Northern Populations

Southern Populations

Gro

wth

Gai

n\Lo

ss (%

)

Range Position Considerations, Cont’d

Magnitude of Climate Change (oC)

§  Implications for forest response under CC:

§  Northern populations expected to benefit from some CC

§  Southern populations expected to decline

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§  Existingclimatechangeresistancecouldbeleveragedbyforestregeneration/restorationprograms

§  Specieswithbulkofrangelyingsouthofplantingsitemaybehighlysuitableforplanting

§  Speciesdistributedmostlynorthoftheplantingsitemaybeunsuitable

§  Arangepositionmetriccanbecalculatedusinginformationat:

www.planthardiness.gc.ca

§  ApproachidentifiespopulationsthatarebothnativeandresistanttoCC

!

LegendRed MapleBlack Spruce

Range Position Considerations, Cont’d 11

Common Name MAT at Range Centre

MAT at Planting Site

Range Position Metric

Ten most climatically suitable native species at North Bay, ON:

Green ash 10.9 4.3 6.6Red Maple 10.8 4.3 6.5Ironwood 10.4 4.3 6.1American elm 10.1 4.3 5.8Red Oak 9.8 4.3 5.5American beech 9.8 4.3 5.5Manitoba maple 9.3 4.3 5.0Sugar maple 7.5 4.3 3.2Black cherry 7.5 4.3 3.2Basswood 7.5 4.3 3.2

Ten least climatically suitable native species at North Bay, ON:Black spruce 1.0 4.3 -3.3Jack pine 1.1 4.3 -3.2White spruce 1.2 4.3 -3.1Showy mountain-ash 2.2 4.3 -2.1Eastern larch 2.3 4.3 -2.0Trembling aspen 2.5 4.3 -1.9Balsam poplar 2.6 4.3 -1.7Balsam fir 2.9 4.3 -1.4Eastern white cedar 3.7 4.3 -0.6White birch 3.9 4.3 -0.4

Range Position Considerations, Cont’d 12

§  What is the capacity of range position to buffer CC?

§  Limited by the degree of

phenotypic plasticity in central/northern populations

§  Limited by pool of species at

planting site that are in the northern portion of their range

§  Best considered one tool in the forest restoration toolkit

sp 2

sp 1

sp 4

sp 5

sp 6

Planting site

sp 3

Assisted Gene Flow

§  Falls under umbrella of

assisted migration §  Also called ‘assisted

population migration’ and ‘predictive provenancing’

§  Involves movements of populations within existing species’ range limits

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Range Position

Assisted Gene Flow

Assisted Range Expansion

Intercontinental Movements

Movement Distance

Within Population

Within Range

Near Range

Long Range

Sho

rt-te

rm R

isk

Natural Regen

No Movement

0

“Designer Ecosystems” Genetically Modified Organisms

Assisted Gene Flow, cont’d

§  Well-suited to the forestry context §  Makes use of existing knowledge

on climate-growth relationships (e.g., provenance trials)

§  Builds on existing seed control systems (e.g., seedzones)

§  Benefits from existing seed collection, propogation, distribution, and planting networks

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Assisted Gene Flow, cont’d

§  Many regions are exploring AGF seed transfer systems

§  B.C. recently released a climate-

based seed transfer system

§  Used provenance data to generate transfer functions and critical seed transfer distances (CSTDs)

§  Used CSTDs to identify suitable BEC units for transfer under CC

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Source: O’Neill, G., et al. 2017. A proposed climate-based seed transfer system for British Columbia. Prov. B.C., Victoria, B.C. Tech.Rep. 099.

BAFA

un

BGxh1

BGxw

2

BWBSdk

BWBSmk

BWBSmw

BWBSvk

BWBSwk1

BWBSwk2

BAFAun 1.3549 8.41 6.07 2.8 4.28 3.99 3.38 3.6 2.86

BGxh1 8.41 1.8725 2.5 6.46 6.5 5.09 5.88 4.88 5.87

BGxw2 6.07 2.5 0.4176 4.05 4.28 2.73 3.85 2.58 3.48

BWBSdk 2.8 6.46 4.05 2.359 2.03 1.64 2.32 2.02 0.96

BWBSmk 4.28 6.5 4.28 2.03 0.2023 1.78 3.23 2.98 2.34

BWBSmw 3.99 5.09 2.73 1.64 1.78 1.9013 2.22 1.32 1.26

BWBSvk 3.38 5.88 3.85 2.32 3.23 2.22 0.0529 1.65 1.81

BWBSwk1 3.6 4.88 2.58 2.02 2.98 1.32 1.65 0.5913 1.18

BWBSwk2 2.86 5.87 3.48 0.96 2.34 1.26 1.81 1.18 0.0142

Plantatio

n

SeedSource

Assisted Gene Flow, cont’d

§  Several other tools and approaches have been developed for AGF

§  Seedwhere matches seed sources

and planting sites based on current and future climate

§  Universal response functions use provenance data to predict growth of any seed source at any test site

§  Currently working with OMNRF on a seed zone update similar to that in BC

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Seedwhere analysis showing similarity future climate (2011-2040, CanESM2, RCP8.5) at Grande Prairie and current climate across the area of interest.

Universal response function showing estimated growth of white pine seed sources at potential planting sites. Adapted from (Yang et al., 2015)

Assisted Gene Flow, cont’d

§  What is the capacity of AGF to buffer CC?

§  Commercial tree species span a

range of 18 C on average in Canada, but local adaptation is relatively weak

§  Capacity of AGF depends on

location of population: §  Trailing edge – little can be done §  Central – approx. 3-4 C of buffering

potential §  Leading edge – approx. 8-10 C of

buffering potential

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8-10 C

3-4 C

Strong Local Adaptation

Black Spruce Response Curves

Assisted Range Expansion

§  Falls under umbrella of

assisted migration §  Involves movements outside

existing range limits, but within continent

§  Has generated considerable debate and controversy

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Range Position

Assisted Gene Flow

Assisted Range Expansion

Intercontinental Movements

Movement Distance

Within Population

Within Range

Near Range

Long Range

Sho

rt-te

rm R

isk

Natural Regen

No Movement

0

“Designer Ecosystems” Genetically Modified Organisms

Assisted Range Expansion, cont’d

§  Relatively few real-world examples

§  Torreya Guardians have been moving T. taxifolia seeds and seedlings for decades

§  B.C. has modified guidelines to allow extra-range transfers of western larch

§  Has not been a focus in forestry to date, but AGF-related tools and data apply

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Source: Torreya Guardians website. http://www.torreyaguardians.org/

Assisted Range Expansion, cont’d

§  What is the capacity of ARE to buffer CC?

§  Much less physically restricted than

AGF in addressing CC; limits may depend on policy/societal acceptance

§  Probably required at some point if goal

is to maintain forest productivity

§  Interesting potential applications: §  Transitioning to hardwoods in southern boreal §  Introducing ‘southern’ conifers into boreal, e.g.,

Ponderosa Pine as regen spp in AB

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Ponderosa Pine Climate Envelope 1971-2000

Ponderosa Pine Climate Envelope 2071-2000, RCP8.5

Intercontinental Movements (and other approaches)

§  Involves long distance

movements and engineered solutions

§  Likely highly controversial

and best viewed as ‘desperate measures’

§  That said, many urban trees have intercontinental origins and forest regen is often from breeding programs

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Range Position

Assisted Gene Flow

Assisted Range Expansion

Intercontinental Movements

Movement Distance

Within Population

Within Range

Near Range

Long Range

Sho

rt-te

rm R

isk

Natural Regen

No Movement

0

“Designer Ecosystems” Genetically Modified Organisms

Other Regeneration Considerations - Mixing Seed Sources -

§  CC uncertainty can paralyze adaptation action

§  Forest regeneration should aim

to employ a variety of seed sources

§  Several approaches have been proposed: §  Composite approach (weighted

mix of near and distant seed sources)

§  Admixture (equal mix of near and distant seed sources)

§  Portfolio theory (Crowe and Parker, 2008)

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Source: Bucharova, A., et al. 2018. Mix and match: regional admixture provenancing strikes a balance among different seed-sourcing strategies for ecological restoration. Conservation Genetics, https://doi.org/10.1007/s10592-018-1067-6

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Forest Regeneration and Climate Change – Take-home Messages –

§  There is a variety of forest regeneration options under CC that span a range of risks

§  Range position and assisted gene flow may help maintain/increase forest productivity in central and northern portions of the range

§  Assisted range expansion may be required to maintain forest productivity in some regions, such as the southern boreal

§  Employing a variety of seed sources may be critical for addressing climate change uncertainty