One year after Tropical Storm Iselle toppled hundreds of albizia trees and caused millions of dollars of damage in Puna, the fast-growing tree species remains a major threat not only on Hawaii island, but across the state.
Despite making progress against the non-native tree over the past year, officials say perhaps more than a million of them are spread across the islands and remain easy targets for any powerful storms that may be headed our way.
Most of these trees — notorious for their shallow roots and brittle yet heavy branches — are found in the forest where trunks and limbs will fall harmlessly to the ground. But some — maybe too many — will crash down on roads, power lines, yards and houses, officials warn.
With another storm bearing down on the islands and a busy hurricane season expected through November, some folks are feeling a bit uneasy.
“We’re still vulnerable,” U.S. Forest Service scientist Flint Hughes said last week. “There will be more storms. It’s just a matter of time. It’s just a matter of where and when. It would behoove us to do what we can to be safer.”
When Tropical Storm Iselle slammed into Puna last August, fallen albizia trees left neighborhoods devastated by blocked roads, downed power lines and damaged homes. Scores of residents were trapped without water and power.
“When the power is out for one night, it can be romantic, maybe even fun,” said state Sen. Russell Ruderman (D, Puna). “When the power is out for one week, it’s a really stressful thing.”
An estimated 90 percent of the tree damage caused by the powerful wind and rain of Iselle was blamed on albizia trees, resulting in a public cost of more than $20 million.
Puna has been dealing with the albizia hazard for decades, and Ruderman was sounding the alarm about the safety threat even before Iselle caught the attention of the rest of the state.
Despite 11 bills in last year’s state Legislature asking for funds to tackle the problem, none of the proposals was approved, including a $3 million request from Ruderman, who was trying to underwrite the state’s portion of a multiagency control plan.
Before the session was over, lawmakers did give $1.5 million to the Department of Transportation to take care of hazardous trees along state highways.
“I’m thankful for what we got, but it doesn’t begin to address the problem,” Ruderman said.
The albizia was introduced to Hawaii in 1917 by Hawaii botanist Joseph Rock, who thought the fast-growing trees would help restore the state’s declining forest watersheds. In the following decades, territorial foresters planted 140,000 albizia trees across the state, along with other alien trees such as the eucalyptus and African tulip.
Albizias are among the fastest-growing trees in the world, known to rise up an inch a day and reach 100 feet in 10 years in wet lowland forests. The largest trees are estimated at 150 feet with trunks 48 inches in diameter and massive limbs that break easily in storms or with age.
Because the trees grow so fast, the wood is brittle and weak. Heavy branches can drop with no warning, even from healthy trees.
A full-grown albizia is a graceful and majestic tree that towers above the landscape. Some of the top-heavy canopies are so large, they can shade an area of more than a half-acre.
But over time these trees became a nuisance as they spread into residential areas and around roads and near power lines. Quite a number line the H-3 freeway between Kaneohe and Kailua, for instance.
In Manoa the Lyon Arboretum recently removed 12 trees that towered over main trails because they threatened the many endangered, rare and irreplaceable plants growing below. A second phase of removal will begin next year.
Springer Kaye, manager of the Big Island Invasive Species Committee, said representatives of more than 40 agencies met in May 2013 to talk about the growing albizia problem.
“It was clear that the public stakeholders recognized the cost of albizia,” she said. What wasn’t clear, she added, is whether political leaders understood the cost.
Are lawmakers taking the problem seriously?
“That’s an excellent question,” she said. “There is a perception that this is only a rural problem. But the reality is this is happening everywhere where the environment is wet. They’re creeping in. If I was a legislator in Manoa, Kaneohe and Wahiawa, I would pay attention to this.”
Following Iselle, representatives from state and federal agencies, prompted by U.S. Sen. Brian Schatz, came together to prepare a plan to address the problem on Hawaii island.
The plan starts with clearing the roadways and power corridors and then moves to other areas. The estimated cost: $6 million a year.
Despite a funding shortfall, much progress has been made, according to Kaye:
» Some 300 acres of the albizia forest have been treated with the herbicide Milestone, with 33,000 trees being removed.
» About 300 miles of road affected by hazardous albizia have been identified and mapped.
» Hawaii Electric Light Co. has cleared 30 miles of power lines.
» The state DOT has cleared sections of Highways 130 and Highway 220.
» The Hawaii Invasive Species Council recognized albizia as one of the state’s top 10 invasive species and allocated $100,000 to an overseas search for a natural predator, perhaps an insect, that will target the tree.
» University of Hawaii at Hilo researchers have conducted tests using unmanned aircraft to take aerial imagery to help with management efforts.
» The Big Island Invasive Species Committee has trained 300 people over the last three months to report and treat albizia trees in and near their own East Hawaii neighborhoods.
» Six workshops on the albizia problem were held at the recent Hawaii Conservation Conference in Hilo, attended by conservation officials from around the state.
Hughes, the Forest Service scientist, said there’s a long way to go, but new research has allowed officials to refine techniques and make inroads toward effective, economical and safe ways to attack the problem.
“We can control this if it is made a priority,” he said.
“Something can be done,” said Kaye, the Big Island Invasive Species Committee manager. “These trees went unmanaged for decades. Now we’re just getting started and making a huge amount of progress. We can do it together.”
But Ruderman warned that significant funding will be necessary in Puna and elsewhere to come to grips with a problem that is growing “exponentially.”
“Whatever the cost to control albizia, it’s going to be much less than the cost of the cleanup,” he said. “And every year we wait, controlling it will cost much more.”
