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Creating Storm-Resilient Urban Forests

Creating Storm-Resilient Urban Forests

Presentation given at the 2023 VCE Master Gardener College in Blacksburg, Virginia.

Eric Wiseman

June 09, 2023
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  1. P. Eric Wiseman, PhD
    Associate Professor of Urban and Community Forestry
    Dept. of Forest Resources and Environmental Conservation
    Virginia Tech
    [email protected]
    linktr.ee/EricWiseman
    @vtarborist
    VCE Master Gardener Tree Stewards • June 8, 2023
    Source: indygrit.community/blog
    Creating Storm-Resilient
    Urban Forests

    View Slide

  2. 01  25
    Presentation Outline
    o Future climate and extreme weather events
    o How and why trees fail during storms
    o Characteristics of storm-resilient trees
    o Selecting storm-resilient tree species
    o Cultivating storm-resilient trees
    Goal: Raise awareness about future climate
    threats to urban forests and highlight best
    practices of creating storm-resilient urban forests
    VCE Master Gardener Tree Stewards • June 8, 2023

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  3. o Regardless of human causes, extreme
    weather events are occurring more
    frequently and with greater severity
    o Extreme weather events cause stress on
    trees and predispose them to failure
    o Falling trees endanger lives, damage
    property, and diminish ecosystem services
    o Likelihood of storm damage can be greatly
    reduced through proper species selection,
    planting, maintenance, and protection
    Source: www.apg-
    wi.com/sawyer_county_record/f
    ree
    02  25
    Premises of Presentation
    Source: www.channel3000.com/news/local-news
    VCE Master Gardener Tree Stewards • June 8, 2023

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  4. Source: www.theglobeandmail.com/news/toronto
    03  25
    The Conundrum We Face
    Trees and Urban
    Forests Help Us
    Mitigate and
    Adapt to Climate
    Change
    Climate Change
    Makes Trees and
    Urban Forests
    More Vulnerable
    and Dangerous
    VCE Master Gardener Tree Stewards • June 8, 2023

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  5. 04  25
    The Responsibility We Bear
    Source: www.thespec.com/news/hamilton-region/2021/04/30 Source: twitter.com/SanJoseDOT
    The Urban Forests We
    Create Today Will Face
    the Climate of Tomorrow
    VCE Master Gardener Tree Stewards • June 8, 2023

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  6. 05  25
    Climate Change and Extreme Weather
    Source: nca2018.globalchange.gov/chapter/2 Source: en.wikipedia.org/wiki/Representative_Concentration_Pathway
    Observed and Projected Changes in Carbon Emissions and Temperature
    Radiative Forcing (W/m2) in 2100
    VCE Master Gardener Tree Stewards • June 8, 2023

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  7. 06  25
    Climate Change and Extreme Weather
    Observed and Projected Changes in Annual Average Temperature
    Source: nca2018.globalchange.gov/chapter/2
    VCE Master Gardener Tree Stewards • June 8, 2023

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  8. 07  25
    Climate Change and Extreme Weather
    Observed and Projected Change in Heavy Precipitation
    Source: nca2018.globalchange.gov/chapter/2
    VCE Master Gardener Tree Stewards • June 8, 2023

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  9. 08  25
    Fitzpatrick, M. C., & Dunn, R. R. (2019). Contemporary climatic analogs for 540 North
    American urban areas in the late 21st century. Nature Communications, 10(1), 614.
    Source: fitzlab.shinyapps.io/cityapp
    Climate Change and Extreme Weather
    VCE Master Gardener Tree Stewards • June 8, 2023

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  10. Source: www.purdue.edu
    Source: theloopny.com Source: www.gfc.state.ga.us
    UPROOTING STEM FAILURE BRANCH FAILURE
    09  25
    How Do Trees Fail During Storms?
    Failure is loss of structural integrity in tree parts that
    compromises tree stability and jeopardizes people and property
    VCE Master Gardener Tree Stewards • June 8, 2023

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  11. o Trees fail when mechanical stress
    (referred to as load) exceeds root
    anchorage or wood fiber strength
    o Gravity acting on the mass of the tree
    exerts internal load on tree parts
    o Ice, snow, and rain add mass and exert
    external load on tree parts
    o Wind intensifies loading stress on tree
    parts
    o Moisture decreases soil strength and
    root adhesion to soil particles
    10  25
    Why Do Trees Fail During Storms?
    VCE Master Gardener Tree Stewards • June 8, 2023

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  12. 11  25
    Why Do Trees Fail During Storms?
    Branch & Trunk Failure
    Windthrow
    Source: www.tdworld.com/vegetation-management/article/21120419/effect-of-wind-in-the-utility-forest
    VCE Master Gardener Tree Stewards • June 8, 2023

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  13. Source: www.theday.com Source: www.rynolawncare.com Source: www.bartlett.com
    12  25
    COMPROMISED ROOTS WEAK BRANCH UNIONS DECAYED/CRACKED WOOD
    What Defects Predisposes Trees to Failing?
    Trees with defects fail with higher frequency and
    under milder storm conditions than sound trees
    VCE Master Gardener Tree Stewards • June 8, 2023

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  14. WOOD STRENGTH PHYSICAL CONFORMATION DEFECT VULNERABILITY
    Density
    Modulus of Rupture/Elasticity
    Decay Resistance
    Root Architecture
    Growth Habit
    Branch Angle, Aspect, & Taper
    Girdling Roots
    Codominant Leaders
    Included Bark
    13  25
    Tree Characteristics and Storm Resilience
    Tree species are quite variable in their wood strength,
    physical conformation, and vulnerability to defect development
    Source: doi.org/10.1039/D0NJ06234K
    VCE Master Gardener Tree Stewards • June 8, 2023

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  15. o Roots well in confined, compacted, and
    hypoxic soils
    o Slow to moderate growth rate with
    dense wood and decay resistance
    o Tendency to develop dominant central
    leader and broad branch angles
    o Coarse branch architecture
    o Moderate foliage and fruit density
    14  25
    Traits of a Storm-Resilient Tree Species
    Selecting Storm-Resilient Tree Species
    There is no perfect tree species!
    Every species has assets and liabilities: species selection is about tradeoffs!
    VCE Master Gardener Tree Stewards • June 8, 2023

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  16. SPECIES THAT SHOULD BE IN
    YOUR URBAN FOREST
    SPECIES YOU SHOULD PONDER
    BEFORE PLANTING
    Japanese cedar (Cryptomeria japonica)
    Ginkgo (Ginkgo biloba)
    Ky. Coffeetree (Gymnocladus dioicus)
    East. Redcedar (Juniperus virginiana)
    Blackgum (Nyssa sylvatica)
    Hophornbeam (Ostrya virginiana)
    Swamp white oak (Quercus bicolor)
    Baldcypress (Taxodium distichum)
    Silver maple (Acer saccharinum)
    Yellowwood (Cladrastis kentukea)
    Leyland cypress (Hesperocyparis leylandii )
    Tulip-poplar (Liriodendron tulipifera)
    White pine (Pinus strobus)
    Poplar (Populus spp.)
    Callery pear (Pyrus calleryana)
    Basswood (Tilia americana)
    15  25
    Selecting Storm-Resilient Tree Species
    There is no perfect tree species!
    Every species has assets and liabilities: species selection is about tradeoffs!
    VCE Master Gardener Tree Stewards • June 8, 2023

    View Slide

  17. 16  25
    Species Selection
    Nursery Quality
    Landscape Placement
    Planting Practices
    Preventive
    Maintenance
    Tree
    Protection
    1
    2
    3
    4
    Cultivating Storm-Resilient Urban Forests
    The Nursery to Woodpile Continuum of Care
    VCE Master Gardener Tree Stewards • June 8, 2023

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  18. 17  25
    Source: www.americanhort.org/page/standards
    Source: hort.ifas.ufl.edu/woody/documents/EP313.pdf
    Dominant Leader Scaffold Branching
    Cultivating Storm-Resilient Urban Forests
    Nursery Stock Quality
    VCE Master Gardener Tree Stewards • June 8, 2023

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  19. 18  25
    Source: Watson & Himelick. (2013).
    Source: hort.ifas.ufl.edu/woody/documents/EP313.pdf
    Well-Formed Roots
    Cultivating Storm-Resilient Urban Forests
    Nursery Stock Quality
    Source: shadetreeexpert.com/transplanting-problems
    VCE Master Gardener Tree Stewards • June 8, 2023

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  20. 19  25
    Source: www.liherald.com/stories/tropical-storm-isaias-hits-east-meadow,126971 Source: boomforest.org/en
    Cultivating Storm-Resilient Urban Forests
    Landscape Placement
    VCE Master Gardener Tree Stewards • June 8, 2023

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  21. 20  25
    Source: archello.com/product/silva-cell-2
    Source: thefield.asla.org/2014/02/19/structural-soil-part-2
    Cultivating Storm-Resilient Urban Forests
    Landscape Placement
    VCE Master Gardener Tree Stewards • June 8, 2023

    View Slide

  22. 21  25
    Source: hort.ifas.ufl.edu/woody/details-specs.shtml
    Cultivating Storm-Resilient Urban Forests
    Planting Practices
    VCE Master Gardener Tree Stewards • June 8, 2023

    View Slide

  23. 22  25
    Source: edis.ifas.ufl.edu/publication/ep315
    Before After
    Cultivating Storm-Resilient Urban Forests
    Preventive Maintenance
    VCE Master Gardener Tree Stewards • June 8, 2023

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  24. 23  25
    Source: www.spsonline.com/sps
    Cultivating Storm-Resilient Urban Forests
    Source: washingtondnr.wordpress.com
    Preventive Maintenance
    VCE Master Gardener Tree Stewards • June 8, 2023

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  25. 24  25
    Cultivating Storm-Resilient Urban Forests
    Construction Protection
    VCE Master Gardener Tree Stewards • June 8, 2023

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  26. o Future climate is likely to bring increased
    frequency and intensity of storms
    o Storms increase risk of tree failure,
    especially for defective trees
    o Tree species selection is foundational to
    storm resilience
    o Urban forests need a continuum of care to
    endure lifelong threats from storms
    25  25
    Take Home Messages
    Source: unsplash.com/photos/UewgGfZgYj0
    VCE Master Gardener Tree Stewards • June 8, 2023

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  27. P. Eric Wiseman, PhD
    Associate Professor of Urban and Community Forestry
    Dept. of Forest Resources and Environmental Conservation
    Virginia Tech
    [email protected]
    linktr.ee/EricWiseman
    @vtarborist
    Creating Storm-Resilient
    Urban Forests
    VCE Master Gardener Tree Stewards • June 8, 2023

    View Slide