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Royal palm trees in Miami Beach, Florida, showing leaf burn due
to salt water flooding. Photo by Mark Williams
This Hong Kong orchid tree (left) in Miami Beach, Florida died
after salt water flooding. Photo by Mark Williams
Cer tain tree species in Miami Beach have proven to be
highly susceptible to damage from salt water flooding.
These include but are not limited to trumpet trees (Tabebuia
spp.), royal poinciana (Delonix regia), tree forms of privet
(Ligustrum spp.), Brazilian beautyleaf (Calophyllum brasil
-
iense) and Hong Kong orchid (Bauhinia blakeana). Common
symptoms of damage include extreme leaf chlorosis, new
foliage stunting, canopy dieback, sudden leaf drop, and—in
severe cases—total tree defoliation and death. The trees
that have proven to be highly tolerant of salt water flooding
include pitch apple (Clusia rosea), seagrape (Coccoloba
uvifera), green or silver buttonwood (Conocarpus erec
-
tus and C. erectus var. sericeus), gumbo limbo (Bursera
simaruba) and paradise tree (Simarouba glauca). However,
the City has observed situations where flooding that per-
sisted for a week or more caused damage even to highly
salt-tolerant tree species.
In anticipation of higher brackish ground water tables and more
frequent salt water flooding events, the City has modified the
reforestation program, emphasizing highly salt-tolerant Florida
native trees and phasing out salt-intolerant material. Design
changes are also being incorporated, such as bridged side-
walks, tree wells to protect existing trees from grade changes
related to flood mitigation, increased use of bonded aggregate,
and raised or mounded planting areas for new trees. Root aer-
ation systems are also being explored. Continued outside-the-
box thinking and attention to the latest research pertaining to
trees and flooding/salt tolerance will help keep the City ahead
of the curve.
—Mark Williams, Urban Forester, City of Miami Beach,
Florida
