Endangered Species in the Pacific Islands
Recovery Plan for the Gouania hillebrandii
||Gouania hillebrandii is a shrub that grows up to 6 feet (2 meters), often comprised of a single unbranched or sparingly branched stem when less than 2 feet but becoming more branched and rounded with increased height.
There is distinct variation between the Maui and Moloka‘i plants that may be considered different forms. The West Maui form is an upright, erect woody shrub with compact leaves. In contrast, the Moloka‘i plants have widely or loosely spreading leaves. They grow more prostrate and vine-like along the ground, weakly climbing on other vegetation. Both forms have small white flowers.
Gouania hillebrandii - Photo credit
Habitat & Distribution:
G. hillebrandii occurs in lowland dry shrubland habitat on leeward slopes of the West Maui mountains and in lowland mesic forest habitat on East Moloka‘i. Population estimates total less than 2,000 individuals. The West Maui lowland dry shrubland habitat where G. hillebrandii occurs is one of the best remnants of this habitat type in the Hawaiian Islands and represents a mosaic of native shrubs such as a‘ali‘i (Dodonaea viscosa) and pukiawe (Styphelia tameiameiae) and native grasses such as kewelu (Eragrostis sp.) and pili (Heteropogon contortus).
An equally unique lowland mesic forest patch exists on Moloka‘i consisting of G. hillebrandii, halapepe (Pleomele auwahiensis), lama (Diospyros sandwicensis), Neraudia sericea, the endangered Zanthoxylum hawaiiense, and kulu‘i (Nototrichium sandwicense) as well as many other common native shrubs and herbs.
On Maui, located above Lahaina on the west facing slopes forming the south wall of Kahana Stream between 1,100 and 1,600 feet (335 and 487 meters), this subpopulation occupies roughly 15 acres within a designated critical habitat of about 50 acres on three ridges of weathered trachyte lava.
Critical habitat is land designated and protected by the Federal government for certain endangered species. The Lihau subpopulation is on State lands managed by the State of Hawai‘i Department of Land and Natural Resources. It occurs on roughly 10 acres within a designated critical habitat of about 60 acres on the west facing foothills at Lihau, between 800 and 1,700 feet (243 and 518 meters) in elevation.
On Moloka‘i, there are two small populations consisting of just a few plants each located just below Pu‘u Kolekole on private land. Several valleys form below Pu‘u Kolekole at an elevation of approximately 3,000 feet (910 meters), where each population may be found on the valley walls in separate drainages. No critical habitat has been designated for the Moloka‘i populations.
Cattle browsing and trampling, alien plants Pinnaspis strachni (Hibiscus Snow Scale), leaf-chewing insects, and fire are threats to G. hillerbrandii. Fire destroyed much of the Pu‘u Hipa population on West Maui in 2007. Strategic fences have been placed on ridges in the West Maui Watershed Partnership to protect these populations from ungulates. These plant populations exist in areas that are remote and difficult to access, thus there have been few in situ conservation efforts for this species.