ADAPTING OUR URBAN FORESTS TO A CHANGING CLIMATE Leslie Brandt, PhD
Climate Change Specialist
URBAN FORESTS
All publicly and privately owned trees within an urban area— including
individual trees along streets and in backyards, as well as stands of remnant
forest (Nowak et al. 2001).
ENERGY USE
Reduced cooling from shade Reduced heating from windbreaks
Annual economic value: $2.8 million
WATER QUALITY AND FLOW Precipitation
Evapotranspiration
Stemflow
Throughfall
$3.4 million annual value for stormwater runoff reductions
COMMUNITY RESILIENCE
URBAN FORESTS: A CLIMATE ADAPTATION STRATEGY?
Ten-Year Urban Forestry Action Plan: 2016 -2026
National Urban and Community Forestry Advisory Council
Cities that include trees as part of their climate
change/sustainability goals in climate action plans
States that have developed comprehensive Climate Action
Plans, using forests to help adapt/mitigate
Cities that view trees as part of their overall
sustainability/climate protection efforts
ST. PAUL’S URBAN FOREST
Over $10 million in benefits (energy reduction, stormwater, aesthetic, air quality)
32.% Canopy Cover:
• 66.2% of Saint Paul is suitable for tree canopy cover
• Residential, single-family parcels offer the greatest opportunity
Species Composition:
• 1 in 5 city trees is an ash tree (EAB)
• Maples make up a similar percentage.
Source: https://www.stpaul.gov/departments/parks-recreation/natural-resources/forestry/urban-tree-canopy
IMPACTS
HARDINESS ZONE PROJECTIONS Low emissions High emissions
5a-5b
5b-6b
5b-7a
Now: Zone 4
STRESSORS
Drought Flooding
Storms Disease
LOSING SUITABLE HABITAT
http://www.fs.fed.us/nrs/atlas/
Paper birch Balsam fir Black spruce
White spruce White pine
LOSING SUITABLE HABITAT
Sugar Maple
American linden/basswood
Chokecherry
http://www.fs.fed.us/nrs/atlas/
GAINING HABITAT
Wild plum
Eastern redbud
Ohio buckeye
HOW DO WE ADAPT?
ADAPTATION OPTIONS
Reduce impacts/ Maintain current
conditions
Forward-looking/ Promote change
Resistance Transition Resilience
THINGS YOU CAN DO AT HOME Resist change:
• Water during hot, dry periods
• Using systematic insecticides for ash trees on private property
• Protect/maintain cold-adapted trees on the north side of buildings/north facing slopes
THINGS YOU CAN DO AT HOME Build resilience:
• Increase biodiversity-plant something different!
• Plant trees and other native plants that can withstand a variety of stressors (drought, flooding, wind)
• Prune to reduce susceptibility to storm damage
• Plant trees at the proper depth
THINGS YOU CAN DO AT HOME
Facilitate transitions
• rain gardens
• rain barrels
• Plant southern species
• Plant prairie plants in hot, sunny spots
URBAN FORESTRY CLIMATE CHANGE RESPONSE FRAMEWORK
Brandt et al. 2016. Environmental Science and Policy
EXAMPLE: HENNEPIN COUNTY
20
Gravel bed nursery-builds root structure, reduces cost, ensures proper planting
Species selection-southern species (zones 5, 6), growing hickory from seed
LEARN MORE www.forestadaptation.org/urban