“Measuring success of an urban tree planting campaign: Yard tree mortality in Sacramento County, CA”
(Introduction by Joe McBride)
Urban forests provide valuable ecosystem services that motivate tree
planting campaigns, and tree survival is a key element of program
success and projected benefits. I studied mortality in a shade tree
give-away program in Sacramento, CA, monitoring a cohort of 436 young
trees for five years on single-family residential properties. I used
Random Forests to identify the most important risk factors at
different life history stages, and survival analysis to evaluate post-
planting survivorship. Analysis included socioeconomic, biophysical,
and maintenance characteristics. In addition to field observations of
tree planting status, survival, and maintenance, I also collected
property ownership information (renter vs. owner-occupancy, homeowner
change, and foreclosure) through the Multiple Listing Service and
neighborhood socioeconomic characteristics from the U.S. Census. 84.9%
of trees were planted, with 70.9% survivorship at five years
post-planting. Planting rates were higher in neighborhoods with higher
educational attainment, and on owner-occupied properties with stable
residential ownership. Five-year survival was also higher for
properties with stable homeownership, as well as for tree species with
low water use demand. When I incorporated maintenance characteristics
from the first year of field observations, factors related to tree
care were important to survival. Many residents did not adhere to
recommended maintenance practices. These results illustrate the
critical role of stewardship and consistent homeownership to young
tree mortality on residential properties, and suggest that survival
assumptions in urban forest cost-benefit models may be overly
optimistic.
I wouldn’t be here without…
My husband and my parents, for taking care of the new baby and
ensuring that I got enough sleep. And little Lucy herself, for
tolerating field work in utero.
I’d like to thank…
My dissertation committee – Joe McBride, John Battles, and Louise
Mozingo – for their support. My community partners at the Sac Tree
Foundation and SMUD, for being wonderful collaborators. Data
collection was made possible with the help of a ton of SPUR and URAP
student field assistants, plus some great CNR senior thesis students
(Melissa Chun, Jeannette Aames, Suzanne Robinson, Sophie Ashton).