Title: Ecology and management of Sheoak (Casuarina spp.), an invader of coastal Florida, USA
Abstract: The Casuarina spp. are invasive plants in
Florida that threaten biological diversity and beach integrity of coastal
habitats. The trees include three species and their hybrids that aggressively
invade riverine and coastal areas. Of the three species, C.
equisetifolia and C. glauca are highly salt tolerant and
widespread in coastal areas. The third species, C. cunninghamiana,
invades riverine habitats. These species pose dangers to both the environment
and public safety. The environmental damage includes interfering with nesting by
endangered sea turtles, American crocodiles and the rare swallow-tailed kite.
Additionally, allelochemical leachates reduce germination and establishment of
native vegetation. Casuarina-infested beaches are more prone to sand loss and
erosion. Moreover, with shallow roots and tall canopies they are among the first
trees to fall in high winds and as such restrict evacuation efforts during
hurricanes. Control of these species is mostly with herbicides requiring
repeated applications and monitoring. One of the most cost-effective means of
controlling these invasive species would be with classical biological control.
Australian surveys for potential biological control agents began in 2004
resulting in the discovery of several promising candidates. These include
seed-feeding torymid wasps, defoliating caterpillars and weevils, leaf tip
gall-formers from cecidomyiid midges, and sap-feeding psyllids. Continued work
is needed to determine the suitability of these species for biological control.
Despite conflicts of interest expressed by some homeowners and the agricultural
industry who value the trees for shade and windbreaks, there are good prospects
for safe and effective biological control of these invasive species. [Greg
Wheeler, Gary Taylor, John Gaskin, Matthew Purcell, Charles Finkl (2010) Ecology
and management of Sheoak (Casuarina spp.), an invader of coastal Florida, USA.
Journal of Coastal Research In-Press.]
Keywords: Australian pine, invasive species, biological control, weeds