Albizia trees are a growing problem in Hawaii

By Cam Tran
Published On: Feb 21 2014 08:15:22 PM HST

Fast growing Albizia trees can grow up to 120 feet but their brittle branches snap easily and can fall on homes, roads, or cars.


During sunset, tall Albizia trees can strike a majestic pose offering a breathtaking image of the Hawaii landscape.

Click here to watch Cam Tran's story.

But, they can also destroy.

"It takes out power lines.  It's even blocked some of our major thoroughfares and roadways," said Darryl Oliveira of the Hawaii County Civil Defense.

Towering Albizia trees arrived in the islands in the early 1900s from Indonesia, brought in to restore Hawaii's forests.

Now, the Hawaii Invasive Species Council says the same characteristics that made them desirable now make them a menace.  They sprout in empty lots along highways and in forests.

"They are incredibly fast growing," said Josh Atwood of the Hawaii Invasive Species Council.  "They grow 20 feet their first year and 120 feet over their life."

An average tree grows about two feet a year, so Albizias grow at a rate ten times that amount.

"It's putting on new wood so quickly that it's not very strong," said Atwood.  "A wind event can easily break off the upper branches."

A wind storm on the Big Island in January caused an Albizia tree to come crashing down on a Jeep.  Another dropped its branches, blocking off North Kulani Street.

Oliveira is bothered by seeing these trees lining roadwasy in Hilo and Puna.

"We've had at least two incidents where trees have come down and blocked the route to the hospital.  Fortunately, there are other routes, but it does definitely impede or slow down our ambulances getting into the emergency room," said Oliveira.

The Albizia can quickly change Hawaii's scenery.

Residents in Ainako used to have a clear view of Hilo Bay.  But, those Albizia trees grow so fast and so tall, that view is now blocked by those tree tops.

Albizia is not just a Big Island problem.

At Lyon Arboretum on Oahu, the falling Albizia branches are threatening the rest of the forest.

"We have very rare endangered palm species from Papua New Guinea.  These species were wild collected and only planted one area of the garden," said Jamilee Kempton, an arborist at Lyon Arboretum.  "We have some species where they are absolutely irreplaceable."

On Oahu and Kauai, the Albizia creep up along the mountain side with their canopy towering over native foliage.

That's where University of Hawaii scientist Dr. James Leary steps in.  Dr. Leary spends his career getting rid of weeds and he says he found a way to curb the growing Albizia problem.

The professor cuts slits on the side of the trunk and puts several droplets of herbicide in each cut.  He says this simple application can easily kill a towering Albizia tree.

"When we make a cut into the tree and around the bark, we're actually making a cut into the vascular system of the tree so when we apply the herbicide, it's being taken up in the vascular system and moving into the canopy and it defoliates and kills the tree that way," said Dr. Leary.

Leary says within a month, the tree will start losing its leaves and will be dead in a year.

"It usually falls apart into place.  You don't see it topple over, per se, but the decomposition takes 2-to-3 years post treatment," said Leary.

Often times, the dead tree can fall on its own.  That's why the doctor only uses the method in dense forests away from populated areas.  It's also cost effective.

Getting a professional to cut down a large Albizia tree can cost a couple thousand dollars to tens of thousands of dollars.  But, using Dr. Leary's method with the hatchet using a hatchet and herbicide, killing a large tree costs around $5.

But, this method is not a quick fix.

Experts say fighting Albizia will be an expensive mission with the price tag in the millions.  But, many on the Big Island say something needs to be done soon before the problem goes from destructive to deadly.

There is a bill before the House committee to allocate $5 million for DLNR to get rid of trees along tsunami evacuation routes.  The bill is now scheduled for a hearing in the finance committee.


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