The Resilient Canopy
Oaks and elms dominate the San Antonio, Texas urban
forest—and they are stressed. Michael Holinsky is trialing
tulip tree, anacua, Kentucky coffee tree, and other members of
underutilized plant families.
By Michelle Sutton
In 2023, record-setting dry heat and prolonged drought
taxed the trees—native and non-native alike—of San Antonio
and the South Texas region at large. In early November,
2023, the San Antonio Express-News reported only 17.5
(444 mm) inches of cumulative rainfall—10.8 inches (274
mm) below average for the year, putting most of South
Texas under severe drought. This level of drought is not
manageable through City watering regimes alone.
Yet, as hot and dry as San Antonio can be, it is also sit-
uated on the eastern edge of a region known as
Flash
Flood Alley, owing to the steep terrain of the San Antonio
River Basin along with its shallow soils and narrow river
channels. Thus, flooding potential also has to inform
Holinsky's tree selection and management decisions.
UCFS Member and San Antonio,
Texas City Forester Michael Holinsky
brings a unique point of view to man-
aging urban forests under stress from
climate change. Holinsky grew up in
Canada and worked as a forester for
the City of Halifax, Nova Scotia before
moving in 2021 to work for the San
Antonio Urban Forestry Division of
the Parks and Recreation Department.
There are also unseasonably late and hard
freezes to contend with, like the one in
early February, 2023, that started a spiral
of decline for certain species of trees,
putting them in a vulnerable position vis a
vis the summer drought. "It's an onslaught
of changing conditions," Holinsky says.
"In 2023, we lost quite a few trees from
marginally drought-tolerant species like
native pecans (Carya illinoinensis), cedar
elms (Ulmus crassifolia), and sugarberry
trees (Celtis laevigata). Even the normally
durable southern live oaks (Quercus virgin-
iana) showed some dieback and leaf drop
as a means of coping with the drought—
though I expect them to fully recover."
Meanwhile, the Texas live oak (Q. fusi-
formis) has been rock solid, Holinsky
says. A botanical synonym for Texas
live oak is Q. virginiana var. fusiformis;
it is also known as escarpment oak or
plateau oak, because it thrives in the
shallow, rocky, alkaline soils of Texas Hill
Country plateaus. Its origins foretell its
success in the dry conditions, high-pH
soils, and limited soil volume often
facing San Antonio's urban trees. >>
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