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is a desirable replacement for London plane where
there's adequate above- and below-ground space, and
trident maple (Acer buergerianum) is a sweetie for under
wires that needs little to no water once established.
"We're also using cool eucalypts, like red flowering
gum (Eucalyptus ficifolia), as medium-maturing ever-
green tree replacements," Kesterson says. "It's about
finding a creative piece for the puzzle at hand and
not just coasting on what's been done in the past."
When nurseries sell trees new to the trade, Kesterson
will buy 3-5 of anything to try it out and share his
findings with nearby urban foresters and colleagues.
"Nurseries need support—and reinforcement to try
growing new things," he says. The City is starting
to contract-grow what they want, to "prime the
pump" for another city that might not be positioned
to experiment with new taxa. "When we buy 50 of
something new for Berkeley, the nursery may grow
50 more that they can sell to others," Kesterson says.
Kesterson has found the research-based SelecTree:
Tree Selection Guide from Cal Poly to be indis-
pensable for learning and sharing knowledge.
californica) in the ground.
The City of Berkeley team, excited to plant new
trees with volunteers. From left to right (Ava
Dillard, Ted Degros, and Eybin Tobar).
The Magic of the "80% Good" Approach
In his presentation at the 2025 Western Chapter
ISA Conference & Trade Show in Tucson, Arizona,
Kesterson laid out how to use current research to
help guide our paths to growing the urban forest—
and he addressed how important it is to learn to be
comfortable in a place of "I don't yet know what I'm
doing," recognizing that being vulnerable in that way
can go against unhelpful societal programming.
Kesterson says that the self-protective stance of "I
know how to do everything" closes doors. "But if you
can live with some uncertainty—if you can push away
the feelings of shame that can come with that—you
will try more things, letting them work out or not work
out," he says. "You will be more curious and creative.
You will seek advice from researchers, colleagues, and
nursery professionals; when people help you, bonds
are formed. And then you help other people, and
more bonds form. Your job can be lonely until you
build those relationships—but keep staying open." He
stresses that urban foresters not feel intimidated
by academic researchers. "They need our field >>
