The infamous albizia
By now, the albizia tree (Falcataria moluccana) has taken center stage in the list of invasive species the public is aware of and interested in eradicating.
Following the wrath of tropical storm Iselle, the alien tree species has been fingered as the culprit for toppled power lines and damage in Puna on the Big Island, as reported earlier in an Aug. 20 story in the Honolulu Star-Advertiser. Officials estimated at least 90 percent of trees that caused damage in the Aug. 7 tropical storm were albizias, trees native to Indonesia that have shallow roots and brittle branches.
"It's not going to go away," said Tracy Johnson, a research entomologist for the U.S. Forest Reserve, who has been working to eradicate them for more than a decade. "There's no way we can remove every tree and be done with it. It's going to remain here, so we have to manage it. Ideally, what we would like to find is a biocontrol that can limit its ability to spread so the problem doesn't get any worst. We're hoping to find something that attacks the flowers, the fruit of the tree."
It's not the first time that it's happened, of course. In the aftermath of tropical storm Flossie last summer, an albizia tree in Hilo fell over, pictured above. An albizia fell over a residential street in Puna in 2010, destroying power ilnes and fences. Albizia trees fell over on Kauai in 2009, dropping on to cars and a house.
Most people probably did't notice the albizias before they fell. After all, they're not unsightly. They aren't on the O‘ahu Invasive Species Committee's list of priority target pests.
Here are some facts about albizias:
>> The trees, native to Indonesia, were first introduced to Hawaii in 1917 by botanist Joseph Rock.
>> They were planted in Manoa valley to provide shade. On Oahu, they can also be found along Pali and Likelike Highways, not an ideal situation.
>> They grow up to 150 feet, have weak wood and tend to grow top-heavy canopies that overwhelm native species. They dramatically increase inputs of nitrogen, displacing native trees.
Johnson just received a $100,000 state grant to search for biocontrol agents that can help control the trees, but that's just the beginning to finding a solution, he said of a five to 10-year process or longer. He'll be searching for natural albizia enemies in Indonesia, the Soloman Islands and Papua New Guinea. Ideally, a biocontrol that attacks the albizia flowers to limits its ability to spread.
With a focus on protecting the native forests on Hawaii island, Johnson's work also involves efforts to eradicate other invasive trees and shrubs that take over quickly, choking out native trees and plants, such as:
>> Strawberry guava: Native to southeastern Brazil, brought to Hawaii in 1825 for its fruit and ornamental attributes. Occurs on all six of Hawaii's largest isles, poses a major threat to Hawaii's endemic flora and fauna. Forms impenetrable thickets and can alter water production and provide refuge for fruit flies.
>> Miconia: On Hawaii's list of most invasive horticultural plants. Originally from south and central America, this prolific seeder poses a threat to Oahu's forested watershed.
>> Clidemia: Also known as Koster's curse, this invasive shrub from central and South America forms dense thickets in tropical forest understories. It has spread to Oahu, the Big Island, Molokai, Maui, Kauai and Lanai.