GARDEN GUY: ‘The tree that ate Puna’


In view of the problems created by Tropical Storm Iselle and the albizia trees, here is an article originally printed in 2011:

The albizia trees that quickly spring up in vacant lots or recently cleared land have become one of Hawaii’s worst invasive species. It has been called “the tree that ate Puna”.

This albizia tree, Falcataria moluccana or Albizia falcate, A.moluccana and others, is a native to such places as Papua New Guinea, the Bismark Archipelago and the Solomon Islands. The wood is used for light weight construction, cabinets, furniture, toys and match sticks.

It is a fast growing tree to more than 100 feet tall. The tree can reach heights of more than 20 feet in the first year and 60 feet by the end of 10 years.

It is described as a deciduous tree with wide-spreading branches, capable of shading more than half an acre. The tree produces large seed pods 4-5 inches long and about 3/4 of an inch wide. It grows from sea level to about 3,200 feet elevation.\

It is a nitrogen fixer, meaning with the help of some bacteria residing in its roots, it can pull nitrogen out of the air and convert it to a form that roots can absorb. Because of this ability, it is used in many countries to improve soils as well as provide shade in coffee plantations.

J.B. Friday, Extension Forester with the University of Hawaii, said, “In Hawaii, this tree is invasive in native ‘ohi‘a forests as well as on land disturbed by human activities, especially bulldozing. It causes the ‘ohi‘a to die off and makes it easier for other invasive species like strawberry guava, clidemia and possibly miconia to grow under it and further degrade the forest. It also improves habitat for the coqui. It is a distinct threat to our native wet lowland forest ecosystems such as there are in Puna.”

Because of their brittle wood and weak structure, these trees are an even more serious problem to homeowners.

Strong winds can cause large limbs to drop onto whatever might be underneath them, damaging to homes, other structures and power lines. The fragile branches often cause traffic hazards by falling on the highway.

A major problem, especially in Puna, is that people sometimes hire a bulldozer to clear their land. They clear the native ‘ohi‘a/uluhe forest, which is somewhat resistant to albizia invasion. Absentee landowners, who might return after a few years, can find an albizia forest has sprung up. Albizia is much bigger and faster growing than ‘ohi‘a, so the native trees cannot compete.

To complicate matters, there is now a source of seedpods for the alibizia to invade the neighbors’ land. You should not clear the native forest on your lot unless you have another use planned for it. Otherwise, albizia will come in and take over and you’ll have a huge problem.

What to do: Leave the natural vegetation untouched — don’t bulldoze — until you are ready to use the land. Eliminate albizia seedlings and small trees before they become a problem.

Methods of control:

• After trees are cut down, immediately apply herbicide to cut stumps.

• Triclopyramine is effective at concentrations of 7-10 percent.

• For larger trees near buildings, it might be advisable to first contact an arborist to determine the safest and most effective course of action to take in removing the tree.

The US Forestry Service in Hilo has an excellent publication titled “Albizia — The Tree That Ate Puna” authored by C. Sumida, F. Hughes and Kathleen Friday. You also can write to: USDA Forest Service, Institute of Pacific Islands Forestry, 60 Nowelo St., Hilo 96720.

Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at askthegarden guy@earthlink.net. You also can visit his website at www.gardenguyhawaii.com.

 

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