Plan aims to guide battle against destructive albizia tree

It’s no secret that large swaths of the fast-growing and hazardous albizia tree infest the islands, representing many millions of dollars in potential damage to roads, transmission lines, buildings and property.

To minimize the risk, the Hawaii Invasive Species Council, which was created by the state Legislature in 2003, has a strategic plan that addresses the problem for the first time on a statewide scale.

The good news, according to the plan, is that large-scale control of the species is indeed feasible. The bad news is that it’s not going to be cheap.

“The plan gives us strategic direction,” said Joshua Atwood, Hawaii Invasive Species Council program director. “But it will take a lot of resources.”

The document does not necessarily aim to eradicate all albizia trees, but to manage and reduce their impact on the state’s environment, human health and infrastructure.

The cost of controlling albizia trees depends on the location. While trees in undeveloped areas can be treated with herbicide and killed in place for less than a dollar, those in close proximity to people and property can cost as much as $10,000 per tree, Atwood said.

A first step is creating detailed and site-specific action plans for Kauai, Oahu, Molokai, Maui, Lanai and Hawaii island and boosting funding for management efforts statewide.

How much money is needed is unknown at this time, but clarity might emerge in another six weeks or so.

That’s when a study led by University of Hawaii- West Oahu professor Jason Levy will be completed that will not only map the size of the state’s albizia population, but offer an economic analysis of the hazardous trees’ impact on the state economy.

Quantifying the potential damage is especially important, according to the plan, to tap into funds from the Federal Emergency Management Agency, which requires analysis studies to apply for grants and other money earmarked for controlling such hazards.

The albizia was responsible for tens of millions of dollars of damage on the Big Island from Tropical Storm Iselle in 2014. The cyclone knocked down hundreds of albizias, leaving Puna a quagmire of damaged houses, blocked roads, downed power lines and blackouts.

Invasive-species officials were already wary of problems linked to the albizia, which was brought to Hawaii 100 years ago by foresters who believed it would protect Hawaii’s declining forest watersheds. They planted 140,000 albi­zias across the state along with other non-native trees.

“Iselle really woke up everyone to the potential damage,” Atwood said. “It made it a lot more real.”

The albizia is one of the fastest-growing trees on Earth, capable of growing up to 15 feet a year and easily reaching 100 feet in height. The rapid growth results in massive trunks and heavy limbs that are structurally weak and known to drop in wind storms or for no reason at all.

A full-grown albizia is an attractive tree that towers over the rest of the Hawaii landscape with a top-heavy canopy capable of shading more than a half-acre.

Following the Iselle disaster, the Big Island Invasive Species joined forces with the state Department of Transportation, Hawaii County Civil Defense, Hawaii Electric Light Co., U.S. Forest Service and other organizations to battle the tree.

The task force is about midway through a five-year plan to tackle 18 priority areas in the Hilo area. The plan was estimated to cost $26 million, but all the projects have come in under budget, said Springer Kaye, manager of the Big Island Invasive Species Committee.

Kaye said she’s optimistic about the future of albizia control in Hawaii.

“We’ve made tremendous headway in just a few years,” Kaye said. “It’s not something we’re going to eradicate, but it is manageable in areas that need to be managed.”

Unlike a species like the little fire ant, albizia can be substantially controlled in one operation and followed up with maintenance work.

“It’s a one-and-done situation,” Kaye said. “In invasive species we don’t usually get that lucky.”

Oahu’s albizia infestation isn’t as pervasive as Hawaii island’s, but there are more roads, trails, power lines and homes with trees encroaching on them, officials said.

The strategic plan, written by former Hawaii Invasive Species Council Planner John-Carl “JC” Watson, says the albizia is also moving into native forests and compromising the state’s hydrology, agriculture and cultural resources.

The plan calls for the removal or treatment of all albizia in key watershed areas and in native forests, especially those home to threatened and endangered species.

Meanwhile, U.S. Forest Service scientists are in the third year of searching for a bio-control agent in the albizia’s native Papua New Guinea. Atwood said promising insect candidates that will attack the tree’s ability to reproduce and limit juvenile growth have been identified, but testing is still needed to ensure the bugs won’t have any negative environmental side effects.