Street Trees and Californias Changing Climate: What to expect, and - - PowerPoint PPT Presentation

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Street Trees and Californias Changing Climate: What to expect, and - - PowerPoint PPT Presentation

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Street Trees and Californias Changing Climate: What to expect, and how to prepare University Avenue, Palo Alto, CA Life Among the Leaves 2017 CAUFC Annual Conference Joe R. McBride and Igor Lacan Department of Landscape

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Street Trees and California’s Changing Climate: What to expect, and how to prepare

“Life Among the Leaves” – 2017 CAUFC Annual Conference”

Joe R. McBride and Igor Lacan

Department of Landscape Architecture and Environmental Planning and University of California Cooperative Extension University of California

University Avenue, Palo Alto, CA

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Problem Facing California’s Urban Forests

from: Cal-adapt.org

Increasing Temperature – San Rafael

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San Rafael, CA July Ave. Max. Temperature (oF) Historic Predicted 79.8o 85.6o

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Problem Facing California’s Urban Forests

from: Cal-adapt.org

Increasing Temperature – Yuba City, CA

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Yuba City, CA July Ave. Max. Temperature (oF) Historic Predicted 93.5o 106.7o

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Change in Precipitation

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Santa Monica (13.2”-> 10.0”) Eureka (40.3” -> 45”) Yuba City (20.5”-> 19.5”) Riverside (10.3”-> 8.3”) Susanville (11.9”-> 14.0”) Burbank (17.3”-> 13.5”)

from: Cal-adapt.org

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Change in Snowpack

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2090 1950 “By the end of this century, the Sierra snowpack is projected to experience a 48-65 percent loss from the historical April 1st average. This loss of snowpack means less water will be available for Californians to use.” California Department of Water Resources (2015).

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Objective

  • 1. Identify the anticipated impacts on street trees by

climate change

  • 2. Describe the physiological consequences of increasing

temperature and decreasing available moisture

  • 3. Report on a project to identify California street trees

that will most likely be impacted by climate change

  • 4. Suggest ideas for management actions today,

in the next few years, and in the coming decades

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What Impacts on Street Trees can we expect as a result

  • f Climate Change?

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Water deficit symptoms range from wilt to tree death.

Water Deficit Injury

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Management implications: Consider providing water ahead of (or during) hot spells

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Leaf necrosis Leaf drop and stem dieback

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Physiological Consequences of Increasing Temperatures

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Photosynthesis and Temperature

Temperature CO Assimilation Photosynthesis

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Respiration and Temperature

Temperature CO Production Respiration

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Photosynthesis, Respiration, and Temperature

Temperature CO Assimilation/Production Photosynthesis Respiration

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95oF 115oF

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Temperature and Tree Growth

Temperature Growth rate

Optimum Minimum Maximum

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Variation among Species

Growth Rate Temperature Birch Oak Olive

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Impact of Higher Temperature

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Current Temperature Range Future Temperature Range

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Physiological Consequences of Decreasing Available Moisture

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Water deficit reduces growth rate and causes undersized leaves and shoots. Water-stressed Sufficient water Drought and tree physiology: problems…

Trees need water to “feed themselves” (photosynthesis) ~ Drought effect # 1 = reduction in growth (which may persist) ~ Drought effect # 2 = less stored energy  lowered plant defenses  facilitates insects, and diseases

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~ Next year’s leaves are made today - growth reduction may persist for at least one year after the drought is over!

Watson and Himelick, 2013

Drought and tree physiology: problems…

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Drought and tree physiology: problems…

~ With enough water: trees can recover, but that may take multiple years ~ With continued lack of water: carbon starvation, and premature death

Watson and Himelick, 2013

Management implications: Don’t panic (that the recovery is not as fast as we would like), but do keep providing water (if available), and make a plan for getting through the next drought

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Impact of Water Stress on Physiological Processes

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Transpiration

  • 10 - 20 - 30 - 40

Leaf Water Stress (bars) Photosynthesis 100 50 150 Percent of Process Respiration

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Variation among Species

Growth Rate Available Moisture Olive Oak Birch

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Impact of Less Water

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Current Moisture Range Future Moisture Range

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Identification of California street trees that will most likely be impacted by climate change

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Method

Application of a method used by plant ecologists to study plant

  • succession. This method is called “substitution of space for time”.

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“substitution of space for time”

  • Fresno

El Centro Temperature oF Current Ave. Predicted Ave. July Max. July Max. Fresno 95 108 El Centro 106

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Urban Forest Composition

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Fresno El Centro

Conclusion: Three of the common street trees in Fresno (B, D, E) will not perform well in Fresno when the temperature of Fresno becomes as warm as the temperature in El Centro. C A A B C E D F G H

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Steps in the Method

  • 1. Select an example city for each of the 16 climate zones

in California

  • 2. Select a comparison city (“warm” city) for each example city

that currently has an average maximum July temperature that the example city will have in 2099

  • 3. Compare the common species in the example city to

the tree species in its comparison city (“warm” city) and to all

  • ther cities that are warmer that its comparison city

“substitution of space for time”

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Climate Zones Cities and Towns

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Selection Criteria for Example Cities within each Climate Zone

  • 1. Temperature

near average for cities in climate zone

  • 2. Size of City

large enough to have ‘ample’ street tree population

  • 3. Geographic Location

typical of the climatic zone

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Cities Selected as Example Cities

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Susanville, California Berkeley, California

Example Cities for the 16 California Climate Zones

1 2 3 4 5 6 7 8 9 16 10 11 12 13 14 15

37 Susanville

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Steps in the Method

  • 1. Select an example city for each of the 16 climate zones

in California

  • 2. Select a comparison city for each example city that currently

has an average maximum July temperature that the example city will have in 2099.

  • 3. Compare the common species in the example city to

the tree species in its comparison city and to all other cities that are warmer that its comparison city “substitution of space for time”

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Historic July Average Maximum Temperatures

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Predicted Weather Data

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Predicted July Average Maximum Temperatures

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from: http://cal-adapt.org/temperature/annual/

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Historic and Predicted July Average Maximum Temperatures

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from: http://cal-adapt.org/temperature/annual/

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Selection of Comparison Cities

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from: http://cal-adapt.org/temperature/annual/

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Selection of Comparison Cities

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from: http://cal-adapt.org/temperature/annual/

?

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Furnace Creek

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Average July Maximum Temperature = 116oF

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Example Cities and Comparison Cities

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Steps in the Method

  • 1. Select an example city for each of the 16 climate zones

in California

  • 2. Select a comparison city for each example city that currently

has an average maximum July temperature that the example city will have in 2099.

  • 3. Compare the common species in the example city to

the tree species in its comparison city and to all other cities that are warmer that its comparison city “substitution of space for time”

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Street Tree Survey

48 From: C. M. Highsmith

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Street Tree Survey – Santa Ana

Locations of Sample Plots (10 x 10 grid)

Santa Ana: 59 grid points fall in the city 50 of these were selected at random for sampling

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Sample Location

Sample Location

(Nearest street Intersection)

  • Grid line intersection

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Arrangement of Sample Plots

100’ 10’

  • North Plots

East Plots South Plots West Plots

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McBride and Lacan off to survey the street trees of California

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Number of Tree Species

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Most Common Species in each Example City

Purple Leaf Plum London Plane Tree Sweetgum London Plane Tree (Eureka) (Ukiah) (Berkeley) (King City) Southern Magnolia Moreton Bay Fig Mexican Fan Palm London Plane Tree (Santa Maria) (Santa Monica) (San Diego) (Santa Ana) Crape Myrtle Mexican Fan Palm Redwood London Plane Tree (Burbank) (Riverside) (Yuba City) (Stockton) Crape Myrtle White Mulberry Silver Wattle Siberian Elm (Fresno) (Barstow) (El Centro) (Susanville) 8 1 3 2 5 9 11 13 4 6 7 10 12 14 16 15

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Berkeley, California

July Average Max. Temp (oF) City Historic Predicted Berkeley 70.3 80.4 Santa Ana 82.3 86.9

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Climate Zone 3

Example City = Berkeley; “Warm” City = Santa Ana

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Common Berkeley street trees and their occurrence in Santa Ana

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Common Berkeley street trees and their occurrence in Santa Ana and warmer cities

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Conclusion

The common street trees in Berkeley will perform well as the climate becomes warmer

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Sweetgum Evergreen Ash London Plane Tree Purple Leaf Chinese Plum Pistache Camphor Tree Black Locust Bradford Pear Southern Magnolia Chinese elm

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July Average Max. Temp (oF) City Historic Predicted Stockton 90.4 101.7 Barstow 99.5 112.5

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Climate Zone 12

Example City = Stockton; “Warm” City = Barstow

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Common Stockton street trees and their occurrence in Barstow

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Common Stockton street trees and their occurrence in Barstow and warmer cities

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Conclusion

Four of the common street trees in Stockton will not perform well as the climate becomes warmer

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Bradford Pear Chinese Elm Chinese Pistache Common Hackberry Crape Myrtle Evergreen Ash London Plane Tree Modesto Ash Purple leaf plum Sweetgum

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Results for the Climate Zones

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16 16 11 12 13 14 16 15 15 14 10 Climate zones where commonly used street trees are not expected to perform well as a result

  • f increasing temperature

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Count of tree species expected to perform poorly

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Legend: count of common tree species current projected

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Species not expected to perform well

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Questions

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  • 1. Could the absence of a species in a comparison

city (“warm” city) be do to a factor other than temperature?

  • 2. How should decreasing available moisture

(decreased rainfall and decreased snowpack) be taken into account?

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Answering the Questions

“We just have a couple of questions”

  • 1. Checking the suitability of the species

to grow in the climatic zone

  • 2. Checking the water needs of the

species

  • 3. Interviews with local arborists,

Urban foresters, and/or tree nursery

  • perators
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10 most Common Street Tree Species - Stockton

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Bradford Pear Chinese Elm Chinese Pistache Common Hackberry Crape Myrtle Evergreen Ash London Plane Tree Modesto Ash Purple-leaf Plum Sweetgum

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Stockton Trees not found in “Warm’ or Warmer” Cities nor Suitable for the future climate of Stockton according to Perry

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Bradford Pear Chinese Elm Chinese Pistache Common Hackberry Crape Myrtle Evergreen Ash London Plane Tree Modesto Ash Purple-leaf Plum Sweetgum

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Irrigation Requirement and Drought Tolerance

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Bradford Pear Chinese Elm Chinese Pistache Common Hackberry Crape Myrtle Evergreen Ash London Plane Tree Modesto Ash Purple-leaf Plum Sweetgum

IR1: M M/L M/L M/L M/L DT2: M-D DT DT DT DT IR1: M M/H M M M DT2: M-D W-D M-D M W-D

1 Irrigation Requirement: M/H = medium to high, M = medium, M/L = medium to low 2 Soil Moisture Tolerance or Drought Tolerance: M-D = moist to dry soil, W-D = wet to dry, M = moist soil, DT = drought tolerant

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Summary

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Consequence of Climate Change:

Some Currently Used Trees will not Perform Well

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Consequence of Climate Change:

We should not be planting trees will not perform well or have high irrigation requirements

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  • Consequence of Climate Change:

Must Identify New Species

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University of California Resources For today: how to irrigate mature trees ccuh.ucdavis.edu

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University of California Resources

For today: …or call Igor for a reminder of the Matheny/Costello Functional Irrigation Approach for mature trees

Soil water reservoir capacity: 2 elements Volume  area*depth, or inches water/foot depth Texture  water stored clay > loam >> sand

1 in on 1 sq ft = 0.62 gal.

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University of California Resources

For the next few years: species likely to perform poorly ucanr.edu/sites/Igor

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University of California Resources For the upcoming decades: species for the future ClimateReadyTrees.ucdavis.edu

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Greetings from

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Climate Change