Tsunami Balm?

In a similar vein to yesterday's post, today the ISW presents another dilemma that pits the problems of invasive species against the needs and desires of humans.

The Indian environmental journal Down to Earth has an interesting article asking whether it is smart to be planting trees and shrubs to act as barriers against tsunamis and other storm action. Many of these "bioshields" are being created from monoculture plantations of Australian pine (Casuarina equisetifolia), a known invasive species. Scientists want to take a step back and approach the protection of the shoreline by examining the coastline more closely, and as the article notes, native species and natural barriers such as sand dunes can also effective at dampening the effect of wave action. However, the government insists that this approach is not practical with so much of the coastline already developed, and will proceed planting trees "wherever we find land."

Oh Pine

Last week the ISW posted about some Australian pines (Casuarina equisetifolia) that have been afforded the perks of historical status in Florida. Turns out the town of Gulf Stream is not the only location dealing with the state's labeling of this species as invasive. NBC2 News is reporting that the island of Sanibel is rebelling against state recommendations to remove their Australian pines. It is not any affection for the trees that has led to the decision, but rather the excessive cost of removal, which can run upwards of $1500 per tree. For now, the city is focusing on getting rid of the trees that threaten utilities or could cause problems on evacuation routes - Aussie pines on private property can be left alone. In 2003 Florida's Palm Beach County had to do some backpedaling after making it compulsory to remove Australian pines and other invasive trees from private property.

History Trumps Ecology, Again

According to this report from the Palm Beach Daily News, the town of Gulf Stream, Florida is going to great lengths to maintain the historical look of a road lined with invasive trees. The Australian pines (Casuarina equisetifolia) were planted back in the 1920s as a salt-tolerant barrier to ocean spray and erosion. Unfortunately, the pines have a shallow root system, making them prone to uprooting in high winds, and not so great for erosion control after all.

Determined to keep the look of their road historically accurate, in 1996 the town had part of the road designated a "scenic vista." Now that the original plantings are dying off, the town's Landmark Preservation Commission, noting that "podocarpus is not a suitable replacement," is working to find a way around the state of Florida's ban on Australian pines. One possibility being considered: the grafting of "sterile" cultivars onto Australian pine bases.

I'm guessing the podocarpus reference is to the yew plum pine (Podocarpus macrophyllus), also a non-native species, but not considered invasive. Are any good native species to replace the pines? One potential alternative is sea grape (Coccoloba uvifera), though it may not be able to attain the proper tree stature...and of course it is completely historically inaccurate :-).

Interested readers will want to check out this ISW post about Australian pine removal in the Florida Keys, and this post about historic Paulownia trees in Philadelphia.

Pining Away

Fort Zachary Taylor Historic State Park in the Florida Keys is going native. But before they do, they're taking precautions to make sure the public understands why they want to get rid of all those shade-giving Australian pines (Casuarina equisetifolia). According to this story from keysnews.com, park managers will hold a public information session to reassure park visitors that the revegetation project will be completed in a sound environmental way and still maintain important recreational features such as shelter and shade.