Guest: Coping with Australian Pines

Published: Tuesday, December 3, 2013 at 1:00 a.m.
Last Modified: Monday, December 2, 2013 at 5:20 p.m.

As a community we can be pretty fickle about trees because we change our minds faster than our favored trees die of old age. So sometimes they get terminated with prejudice, even if they are doing the job they were asked to do. We planted oaks to honor war dead and then cut them all down. Our predecessors combed the planet for interesting subtropical trees, and now some people think these immigrants should go. Immigrants like those demonized Australian Pines.

Eric Ernst, Jeff LaHurd and some letter writers have weighed in on the subject. At the risk of alienating both Australian Pine lovers and haters, let me suggest a middle ground because I think both sides are guilty of overstating their case. Some birds do roost and nest in Australian Pines -- they are not a complete biological desert. On the other hand, John Ringling was wrong about one thing: They don't stabilize beaches. Still, you can see why he was taken with them: They can grow in pure sand and create dense shade that is a respite from the blinding, broiling beach.

Paradoxically, I am an environmentalist believer in both native and introduced plants. There are many native plants that would be inappropriate in an urban setting, and try imagining Selby Gardens or the Ringling Museum grounds without exotics.

So here's my take: There are three major problems with Australian Pines: 1) Their shallow root systems predispose them to tipping over in high winds; 2) their ability to live on beaches (combined with shallow roots) thwarts sea turtle nesting; and 3) their ability to fix nitrogen allows them to invade native ecosystems with low nutrient soils, such as beaches and dunes.

Therefore, it is fairly straightforward to determine where Australian Pines should not be:

1) Adjacent to any roadway that could be part of an evacuation route, if the height of the trees is such that they could block the road if they toppled;

2) On Gulf beaches where even wayward sea turtles might consider nesting;

3) In areas where managers are trying to maintain or restore native habitat.

If we could follow those three rules of thumb, the majority of environmental complaints about Australian Pines would disappear and they could be planted elsewhere. But proliferation concerns would remain, since they can produce a lot of seeds. Luckily there is a horticultural equivalent of a spay-and-release program for Australian Pines.

"Spay and release"

In 1952 George Ruehle published his experimental Australian Pine grafting results (Google "Casuarina grafting"). Without resorting to Latin species names, the common species on the beaches produces seeds but does not sucker. Another species more common inland doesn't produce seeds, but throws up a lot of suckers from the roots. By grafting non-seed producing scion onto non-suckering rootstock, one can produce an Australian Pine incapable of reproduction -- a non-invasive exotic. Why not plant these in the high-use public beach areas where shorebirds and sea turtles would not be found?

Australian Pine lovers should endorse this approach. Or use them on Skier Island, another controversial Australian Pine site, where the tall trees block views of the expensive homes on the opposite shore. Clear a swath down the center of the island, plant these non-reproducing "mules" and let them grow up and block views. Then remove invasive exotics and replace with them with native coastal trees such as Southern Red Cedar, sea grape, and cabbage palms.

And speaking of fickle behavior and cabbage palms, the city of Sarasota is planning to remove more than two-dozen cabbage palms in the 1200 block of Palm Avenue. These steadfast trees create significant shade (unlike the spindly palms across the street next to the parking garage) and they have done nothing wrong -- they haven't overgrown, or lifted sidewalks. The pavers the city wants to put in to replace marginal lawn could be laid around the palms, but, no, progress says they have to go.

Cabbage palms are not controversial invaders, but our state tree, and a fantastic native wildlife plant. With a little gentle pressure-washing on their trunks they could continue to serve admirably for decades. Will they? Or will "the unfeeling axe of progress" claim more victims and another bit of living Sarasota history?

Jono Miller is an activist and community leader best known for his efforts on behalf of the environment. He is an adjunct instructor and Assistant to the Vice President for Finance and Administration at New College of Florida.

This story appeared in print on page A6


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