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

Hakalau Forest National Wildlife Refuge
Comprehensive Conservation Plan
There are nine Sugi groves throughout the HFU (Jeffrey, pers. comm.), mostly in pasture areas, but a
few occur in forest. The species has been shown to grow well in the upper reaches of HFU,
especially under koa. This species was previously planted on the adjacent DHHL as buffer. Sugi pine
is not currently recognized as invasive in Hawai„i; however, Jacobi and Price (2007) note that the
ring of smaller individuals around the original planted sites suggests this species is spreading. Jacobi
and Price have recommended the development of control methods for these groves. In addition, the
Refuge Draft Restoration Management Plan (1996) aims to “to prevent the spread of exotic tree
plantations,” such as Sugi pine, in order to restore native forests. Roughly 42.8 ac, mostly in the
Hakalau Tract, are planned to be removed and replaced with native trees over the next 5-10 years
(NRCS 2005). Sugi pine groves are also potential roosting sites for the endangered „ōpe„ape„a
(Menard, pers. comm.). Because of this unusual circumstance, care needs to be taken with whatever
methods are used to remove the groves. Because Sugi pines are not highly invasive, they are a lower
priority.
Sweet Vernalgrass (Anthoxanthum odoratum)
Sweet vernalgrass was ubiquitous during surveys by Stone et al. (1991) and Barnett and Simonson
(2008). It was less often found in closed-canopy areas. Jacobi and Price (2007) stated that this
species is “relatively ubiquitous and probably not a major concern for Refuge management.” It is
easily shaded out by native vegetation (Jeffrey, pers. comm.).
Weeping Grass or Meadow Ricegrass (Ehrharta stipoides)
Weeping grass or meadow ricegrass is found below 4,650 ft in the openings of wet forests and other
moist areas (Wagner et al. 1999). At the HFU, this perennial grass is widespread below 5,000 ft in
the shaded understory (Jacobi and Price 2007, Barnett and Simonson 2008). Weeping grass has
increased in frequency at the Refuge rising from 69.9 percent in 1987 and to 80.3 percent in 2007
(Jacobi and Price 2007). This species spreads by seed and likely arrived at HFU by a shoelace
(Barnett and Simonson 2008).
Australian Tree Fern (Cyathea cooperi)
The Australian tree fern was introduced to Hawai„i as an ornamental. It is a large tree fern up to 40 ft
tall with large triangular leaves, and scaly brown stems that fall off when dead, leaving oval scars.
The leaf stalks have white hairs unlike native hāpu„u, which have red hairs. The trunk does not have
the thick, soft fiber wrapping like the native hāpu„u. The fronds form a thick overstory preventing
germination and growth of native plants. The spores are wind-dispersed and can travel over 7 miles
from the parent plant. It is fast growing and aggressively outcompetes native plants in the forest
understory. It displaces native ferns, including the slower growing hāpu„u. The Pacific Islands
Ecosystems at Risk (PIER) Assessment rates this plant as (8) “high risk.” It is known on almost all of
the main Hawaiian Islands, and on Hawai„i Island it is spreading from urban areas in Volcano,
Laupāhoehoe, and other areas into native forests. Although this species is not currently found in
either unit of the Hakalau Forest NWR, it is a species to watch for and remove immediately if
detected.
4-108 Chapter 4. Refuge Biology and Habitats