Australian Pine: One of Florida's Least Wanted



Austrailian Pine fruits

Australian pines seem to be everywhere in the coastal regions in the bottom half of Florida. Their name is deceiving because, while they are native to Australia, they aren't pines or even conifers. They are flowering trees with separate male and female flowers, and what look like needles are really green twiglets with close-set circles of tiny leaves that drop at the first sign of a drought. In the photo to the right, the light-colored lines are where leaves where once attached. Most of the photosynthesis takes place in the twiglets.

There are three species of Australian pine (Casuarina spp) that have been imported into Florida for various purposes. They were widely planted to soak up the "swamps" in Florida, stabilize canals, and hold beaches. Unfortunately for Florida's ecosystems, the "pines" accomplished all this and more--like seeding prolifically, growing five feet or more per year, producing dense shade, and emitting an herbicide that kills most any other plant that has the nerve to grow within their collective drip lines. They have root nodules, like a legume, that fix nitrogen in poor soils for use as their own fertilizer, and they can tolerate saltiness. Between 1993 and 2005 the populations in Florida quadrupled. What a successful plant!

Why is their success so bad for Florida? Because the sterile monoculture they form has replaced the normal ecosystem of plants and animals that used to inhabit beaches and many other areas. Our loggerhead turtles, green sea turtles and American crocodiles have lost nesting sites on sandy beaches above the high tide line where "pines" have colonized. Farther inland the "pines" have displaced marsh rabbits, gopher tortoises, and many bird species that depend upon the native plants that were out-competed.

Australian pines caused significant damage in our recent hurricanes. Fast growth makes their wood brittle and they break under pressure. The shallow root system makes them susceptible to uprooting, too. They are highly flammable. So even if you ignored the environmental problems with this tree, it's not a good addition to a stormwise or firewise landscape.

Australian pines are on the Category I list of the most invasive plants according to the Florida Exotic Pest Plant Council (www.fleppc.org); and the Florida Department of Environmental Protection prohibits possession, collection, transportation, cultivation, and importation of these invaders. Even so, several years ago there was a group of Australian pine defenders in Key West. These folks appealed to the local and state governments to prevent removal of these invaders along the beach in Ft. Zachary Taylor State Park. They wrote poems and dramatic essays saying that the "pines" are part of their history and that they love hearing the wind whistle through their needles. I guess they don't remember stepping on those hard, pointy seedpods that are hazardous to bare feet. Their pleas were successful and these invasives are still there today.

Ft. Zachary Taylor State Park in 2/11. The Australian pines have reduced the beach
and have littered the ground with their spiny seedpods. Ouch!

Right next to the state park is the Navy base beach (Truman Annex) where the Australian pines
have been removed. An area next to the beach has been planted with native plants including railroad vine,
blanketflower, mohogany trees, and dune sunflower. Note the Australian pine sprouting in the middle
of their native plantings. Fighting invasives is a long term project!

The military has been working to get rid of Australian pines and other invasives growing on its bases. On the Key West Naval Air Station, a multi-year program to eradicate invasives has begun, but it's not an easy task. The first step is to cut down the trees, but then all of the sprouts from the trunks and roots need to be eliminated. It's a huge job.


Along the shoreline at the Key West Naval Air Station (Trumbo Point) Australian pines have
been chopped down, but now the "pines" have sprouted vigorously and will need to be removed again.
Native mangrove and seagrapes have been left alone, so maybe they'll have more of a chance to thrive.



This area has been further treated and the Australian pine stumps appear to be dead.

But wait, there's more!

The Australian pine is just one of the 140 invasives here in Florida. While controlling invasive plants is a huge task, if we all do what we can to eradicate these aliens, it will make a difference. If any are growing on your property or on community property near you, do what you can to remove them. If you see invasive plants being sold in big box stores or other nurseries, complain.  Replacing aliens with locally native plants that are adapted to Florida's environment will help restore some diversity for the sake of our birds, butterflies, and other wildlife.

This post is part of FNPS's participation in the nationwide "Invasive Awareness Week" from Feb 26th to Mar 5th. Tell us what you've been doing to help eliminate invasives. Thanks.

Ginny Stibolt

So what to do with all those stumps??  Sit on them!