Final Comprehensive Conservation Plan - U.S. Fish and Wildlife ...

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
At the HFU, photinia has been shown to be spreading from its past distribution in 1987, in the upper
elevation forests in the Nauhi Cabin area (Jacobi and Price 2007). Currently, it occurs in the forests
both above and below Nauhi cabin, on both sides of Nauhi Stream, and at elevations 5,200-5,500 ft.
Photinia produces a large number of red fleshy fruits that are dispersed by birds (Jacobi and Price
2007).
Strawberry Guava (Psidium cattleianum)
Strawberry guava is considered one of Hawai„i‟s worst invasive plant species (Wagner et al. 1999,
Motooka et al. 2003, Uowolo and Denslow 2008). Introduced to Hawai„i in 1825, strawberry guava
is widely distributed in the mesic and wet areas throughout the Hawaiian Islands. It tolerates a variety
of habitats up to 4,265 ft elevation. Strawberry guava can form dense, monotypic stands consisting of
trees 20 ft high. These stands suppress and exclude native species (Wagner et al. 1999, Motooka et
al. 2003). Furthermore, strawberry guava has a rapid growth rate and is shade-tolerant. The red fruits
of strawberry guava are eaten by rodents, pigs, and birds. These animals help to disperse and
germinate the prolific seeds. In addition, strawberry guava fruits host crop-damaging fruit flies that
economically impact the State‟s agriculture industry (Motooka et al. 2003, Tummons 2008, Uowolo
and Denslow 2008, USFS 2008).
It has been estimated that strawberry guava has the potential to invade 47 percent of the land area of
Hawai„i Island. At least 10 endangered species are restricted to habitats within this range (USFS
2008). As a result of these factors, strawberry guava is considered an important management concern
at the KFU and the lower elevations of HFU. In 2003, one strawberry guava plant was found along
the Alleyway fence line, in the Middle Honohina Unit, possibly introduced by the fence construction
crew in 1986.
Current control methods are expensive, only temporarily effective, and cause harm to surrounding
nontarget plants. Manually, strawberry guava can be removed by grubbing or using a weed wrench
(USFS 2008). Strawberry guava can also be controlled using herbicides applied to foliage (triclopyr,
dicamba, and 2,4-D), basal bark (triclopyr, 2,4-D, picloram), or cut stumps (triclopyr amine)
(Motooka et al. 2003). Chemical and mechanical control efforts are likely most effective 3 months
after the fruiting season because strawberry guava seeds will not survive beyond this time period
(Uowolo and Denslow 2008). Controlling strawberry guava in natural areas on Hawai„i Island using
only these techniques would cost roughly $18 million (Tummons 2008).
Tectococcus ovatus, a scale insect which reduces fruit and seed production in Brazil, is currently
being studied as a biological control agent for strawberry guava (Uowolo and Denslow 2008). This
insect produces leaf galls, limiting growth, fruiting, and seed production. The initial release site
proposed is the „Ōla„a Forest Reserve on the Island of Hawai‟i (USFS 2008); however, the State draft
environmental assessment is currently pending.
Sugi Pine (Cryptomeria japonica)
Sugi pine is an aromatic evergreen tree found at 2,500-6,000 ft on Kaua„i, Maui, and the Island of
Hawai„i. Large stands exist along the old Volcano Road and in South Kona. This species is grown as
an ornamental and windbreak and the wood is used for fence posts (Elbert and Skolmen 1989).
Chapter 4. Refuge Biology and Habitats 4-107