Thirty-two
rare native plant species that exist only on the islands of
Hawaii and Kauai are being proposed for addition to the Federal
threatened and endangered species list by the U.S. Fish and
Wildlife Service.
Two
species, known in Hawaii as hau kuahiwi, have completely disappeared
in the wild and exist only in private gardens and as cultivated
individuals planted back into their original habitat. Many
other species have five or fewer populations, and several
are represented by fewer than 10 remaining individual plants.
Two plants are proposed as threatened species; the remaining
are proposed for endangered status.
The plants
proposed for listing are scattered across the two islands
at varying elevations and in differing vegetation and climate
zones, but they share in common many of the same threats to
their existence. According to the Fish and Wildlife Service,
competition from introduced plant species; fire; hurricanes;
landslides; habitat destruction by feral or domestic animals;
agricultural, military, and residential development; and predation
by cattle, goats, insects, and rats have all contributed to
bringing these plants close to extinction.
"Of particular
concern are those species with very few individuals remaining,
because a single event such as a fire, a volcanic eruption,
a hurricane, or rooting by feral pigs could quickly wipe out
the species forever," said Robert P. Smith, Pacific Islands
Ecoregion Manager for the Fish and Wildlife Service in Honolulu.
"By adding them to the threatened and endangered species
list, they will not only receive the legal protection afforded
by the Endangered Species Act, but also benefit from activities
aimed at restoring the species to safe population levels."
The small numbers
of populations and individuals of most of these taxa increase
the potential for extinction. The limited gene pool may affect
the plants' ability to make seeds, or a single human-caused
or natural environmental disturbance could destroy a significant
percentage of the individuals or the only known population.
Native plants
are important for their ecological, economic, and aesthetic
values, and Hawaii's plant life is among the Nation's most
unique. Native plants play an important role in the development
of new crops that resist disease, insects, and drought. For
example, the Hawaiian cotton (Gossypium tomentosum) has been
bred with the agricultural strain of cotton to produce a strain
that does not attract ants. This saves the cotton industry
millions of dollars in the cleaning of cotton fibers prior
to use.
At least 25
percent of modern prescription drugs contain ingredients derived
from plant compounds, including treatments for cancer, heart
disease, and malaria, and medicines to assist in organ transplants.
Plants also are being used to develop natural pesticides to
replace chemicals more harmful to people and the environment.
Federal listing
protects plants on Federal lands and requires agencies to
consult with the Fish and Wildlife Service when federally
licensed or permitted projects may affect listed species.
Because Hawaii state law automatically includes federally
listed species on the state threatened and endangered species
list, and the state's endangered species law prohibits the
destruction of imperiled plants on state and private lands,
protection of listed plants also extends to non-Federal lands
in Hawaii.
The two trees
that are extinct in the wild, Hibiscadelphus giffardianus
and Hibiscadelphus hualalaiensis, survive only from cultivated
material. Hibiscadelphus giffardianus is known only from the
Bird Park area of Hawaii Volcanoes National Park. National
Park Service employees have successfully reintroduced 11 trees
to their native habitat. The state Division of Forestry and
Wildlife has planted 24 Hibiscadelphus hualalaiensis seedlings
in the Puuwaawaa area of the Big Island.
Another Hibiscadelphus
species, Hibiscadelphus woodii, was first discovered in 1991
and is known only from its original site in Kauai's Kalalau
Valley on state land. The four remaining trees grow on cliff
walls and are in danger from rock slides. Other threats to
this species are habitat degradation by feral goats and pigs,
competition with alien plant species, and nectar robbing by
the Japanese white-eye, an alien species of bird.
Only a single
population of Labordia tinifolia var. wahiawaensis survives
today, located on private land in a drainage of the Wahiawa
Mountains of Kauai. More than 100 plants were originally known,
but Hurricane Iniki reduced the population to between 20 and
30 individuals. The primary threats to the species are habitat
degradation by pigs, trampling by humans, and competition
with the alien plant strawberry guava.
Phyllostegia
knudsenii, a perennial mint, was historically known only from
the original sample collected in the 1800's. In 1993, one
individual was rediscovered at a single location in Koaie
Canyon on state-owned land. Because only a single individual
is known, this species is particularly vulnerable to extinction.
Other major threats to Phyllostegia knudsenii are habitat
degradation by pigs and goats and competition with alien plants.
A single population
of Pritchardia viscosa, a short palm with silvery-gray undersides
of the leaves, remains on state land, and it contains just
three individuals. This species is at severe risk of extinction
from hurricanes; Hurricane Iniki destroyed half the population
in 1992. Additional threats to Pritchardia viscosa are fruit
predation by rats and competition with alien plants such as
Hilo grass.
Of the more
than 1,500 U.S. and foreign species that are listed as endangered
or threatened, the largest category includes plants -- 529
species are protected. Recovery strategies for listed plants
often include habitat restoration and establishing new populations
through propagation and transplantation.
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