Using Urban Forests to Predict the
Success of Western Red Cedar during
Global Change
Anna O’Brien
University of Washington
Global Change
Global Change
• Ecosystems are changing in their basic characteristics,
to which organisms are often finely adapted
• Temperatures, CO2, & nitrogen deposition (nutrients)
Melting sea ice
&
Animals
Plants
Research Question
• How will our local conifers respond to
global change?
• Pacific Northwest forests are almost entirely made up of
conifer trees, they provide the ecosystem structure on
which countless other organisms depend, and are
economically important
• Conifers will respond to global change variables1, and
predicting this response is critical to conservation and
management efforts
• I focus on Thuja plicata, Western Red Cedar
1. Handa, Korner, Hattenschwiler 2006; Yin, Liu, Lai 2008
Modeling Global Change
• Urban areas resemble global change effects2
• Can therefore use the effects of urban areas on species
and ecosystems to predict the effects of global change
Temperature Nitrogen
deposition
CO2 levels
Future vs
Current
Urban vs
Rural Areas
2.Carreiro and Tripler 2005
Hypotheses
1. Edges of forest with urban influence will have higher
temperatures and soil nitrogen levels than urban forest
centers and rural areas
2. Reproduction of trees will be reduced at urban forest
edges compared to urban forest centers and rural areas.
3. Growth of trees will be increased at urban forest edges
compared to urban forest centers and rural areas.
Thuja plicata
recent
germinant.
Study Site
• Seattle has forested parks in urban neighborhoods.
• Rural area sites included to account for edge effects unrelated
to the urban influence.
UU
U
U
U
R
R
R
IButton
Measurements
Growth: Take
core with
increment borer
Environment: Measure temperature with iButton,
and take soil sample from two locations
Reproduction:
Count seedlings
Environment-N
• Urban nitrogen levels > Rural nitrogen levels (P=.005)
• Urban park edge nitrogen levels may not be significantly greater
than park center levels
Soil Nitrogen (NO3) Levels
25
20
mg NO3/kg 15
dry soil
10
5
0
Rural edge
Rural center
Urban edge
Urban center
Environment-Temperature
• Preliminary Temperature Data
• Edge Temperatures > Center Temperatures
Temperature
(°C)
30
Schmitz Park – Temperatures
EDGE
25
20
15
10
5
CENTER
0
Feb 2009
-5
Jun 2009
Reproduction
• Low germination totals
• Urban Center > Urban Edge
• Rural Edge > Rural Center
Thuja plicata germination at edges and centers
0.35
0.3
Total
0.25
germinants 0.2
0.15
per number 0.1
of plots
0.05
0
Rural Edge
Plots
Rural Center
Plots
Urban Edge
Plots
Urban Center
Plots
Growth
1.
2.
3.
Obtain yearly growth data from tree cores
Obtain yearly temperature data for region & modify to
local sites
Compare temperatures by year to tree growth
Directions
• Why so low germination?
– Lack of viability
– Herbivory
– Fungi3
Thuja plicata seed, USDA plants, 2009
3.Weber, Karst, Gilbert & Kimmins, 2005
Conclusions
1. Environment – Urban edges show influence
consistent with global change
2. Reproduction – Urban edges have a
significant negative effect; low germination
totals concerning
3. Growth – Hypothesize that growth will be
increased at edges compared to other areas
•
•
What is the likely future success of Thuja
plicata?
What does this mean for conservation and
management?
Acknowledgements
•
•
•
•
•
•
Howard Hughes Medical Institute
Janneke Hille Ris Lambers
Brian Buchwitz
Ailene Kane
Irene Weber and Melissa Winstanley
Seattle Parks, Cedar River Watershed, King County Parks, &
Washington State Parks
Questions?