Hawaii was recently hit by tropical storm Iselle. Many streets in some locales, especially an area called Puna, were strewn with uprooted trees and fallen branches. The following article is about those trees - ALBIZIA. These
albizia trees that quickly spring up in vacant lots or recently cleared
land have become one of the worst invasive species on the Big Island of Hawaii. It has been
called “the tree that ate Puna”.
This albizia tree, Falcataria moluccana, is also named Albizia falcate, A.moluccana and others), and 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 over 100 ft. tall. The tree can reach heights
of more than 20 feet in the first year and to 60 feet by the end of ten
years. It is described as a deciduous tree with wide-spreading
branches, capable of shading over half an acre. The tree produces large
seed pods 4-5 inches long and about ¾ inch wide. It grows from sea
level to about 3,200 feet elevation. It is a nitrogen fixer, meaning
that 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.
This
may make it sound like a pretty decent tree. But Dr. J.B. Friday,
Extension Forester with the University of Hawaii, states “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 tiny invasive coqui frog. These trees are a distinct threat to our native wet lowland forest ecosystems such as
there are in Puna.”
Because
of their brittle wood and weak structure, albizias are an even more
serious problem to homeowners. Strong winds can cause large limbs to
drop onto whatever may be underneath them, damaging
homes, other structures and power lines. The fragile branches often
cause traffic hazards by dropping branches on the highway.
A
major problem, especially in Puna, is that people sometimes hire a
bulldozer to clear their land. They clear the native ohia/uluhe forest,
which is somewhat resistant to albizia invasion. If they are absentee
landowners, they may not return for a few years and when they do return,
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 albizia to invade
the neighbors' land. Dr. Friday advises not to clear the native
forest on a 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 utilize 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.
Triclopyr amine is effective at concentrations of 7-10%. For larger
trees near buildings it may be advisable to first contact an arborist to
determine the safest and most effective course of action to take in
removing the tree.
