The skeletal outlines of dying albezia in this Puna forest are testament
to Dr. Leary’s herbicide technique and the dedicated work of the Big Island
Invasive Species crews.
Everyone remembers the toll albizia trees took on Puna during last
summer’s Hurricane Iselle, when they knocked down power lines, blocked roads,
and crushed roofs and cars. Homeowners, natural resource managers, and others
are now eyeing the albizias still standing, with an eye to bringing them down…less
The college’s research and extension faculty have been sounding
the warning about these towering trees for more than a decade. Albizia (Falcataria moluccana, formerly Paraserianthes falcataria or Albizia falcataria) is not only huge and extremely fast
growing; it’s very brittle, meaning branches and trunks can break without warning.
It crowds out and kills off native species, competing for sunlight, water, and nutrients.
And it changes the chemistry of its soil, making it more inviting for other
invasives, including the rapacious strawberry guava.
One element of control of invasive plants, says CTAHR forester J.
B. Friday, who advises landowners and community groups, is not to plant
problematic trees in the first place. “First determine what you want from the
trees you’re planting,” he explains, “and then find non-invasive alternatives
that provide the same benefits.” Albizias have been used as ornamentals, for
reforestation, and as nitrogen-fixers to fertilize soils. Some good alternatives
include monkeypod (Samanea saman), narra (Pterocarpus indicus), and madre de cacao (Gliricidia sepium). Plant Pono, a project with which many CTAHR faculty, staff, and
alumni are associated, provides more alternatives.
Dr. Leary (far right)
with members of the Big Island Invasive Species team.
Invasive plant specialist James Leary deals with the many albizias
already growing. They can be expensive and time-consuming to eradicate, but Dr.
Leary has pioneered a revolutionary technique for delivering mili-doses of
herbicide directly to the trees’ vascular system that costs as little as $2 per
tree and obviates the need for large amounts of chemicals. The dead trees that remain
standing are much less of a threat: A recent article in Landscape Hawaii magazine reported that while the canopies of
live trees acted as sails, causing hurricane winds to blow them down, the
defoliated dead trees remained upright and did no damage. As importantly, dead trees
do not produce new seed.
Dr. Leary comments, “The recent catastrophe of Hurricane Iselle
reminded us of the real hazards presented by albizia. If we are going to spend
millions of dollars physically removing these imminent threats, out of
necessity, we also need to implement more cost-effective prevention strategies,