This species has been recorded from the islands of Molokai, Maui, Lanai, and Kahoolawe. Currently, it is known to be extant only on Molokai and Maui, with 6 occurrences containing fewer than 3,000 plants. The species and its habitats are threatened by cattle, feral goats and pigs, and the invasion of alien plant species. Fire is also a potential threat.
Threats to G. hillebrandii include browsing and grazing by feral and domestic livestock; removal of native vegetation and subsequent replacement by alien species; infestation by the exotic hibiscus snow scale (Pinnaspis strachani), and an unknown leaf-cut
Number of Populations: 3 (USFWS 2001)
Number of Plants: 1700-2100 (USFWS 2001)
The Maui Invasive Species Committee (MISC), a federal-state-private partnership is working to prevent, contain, or eradicate the most serious plant and animal invasions that threaten G. hillebrandii (MISC 2001).
The main management objective is to protect the natural population of G. hillebrandii from threats of browsing and trampling by cattle and other feral or domestic live stock, from insect infestation, competition from alien plants, and from fire. Feral and domestic livestock have probably been the greatest threat historically to the species habitat. Trampling also promoted erosion and compacted soils, while destroying vegetation and litter important to soil-water relations.
The National Tropical Botanical Garden (NTBG) currently has ex situ holdings of 713 seeds in its seed bank, which represents two out of the three populations
1. Undertake management in situ to ensure the continued existence of G. hillebrandii shrub including control of the hibiscus snow scale.
2. Terminating grazing leases on the land that G. hillebrandii exists.
3. Monitoring the population of G. hillebrandii.
4. Controlling insect predators, and preventing and controlling fires.
5. Conduct pollination biology studies on G. hillebrandii.
6. Map genetic diversity in the surviving populations of G. hillebrandii.
7. Test the influence of weeding and fencing on populations of G. hillebrandii.
Recommendations derived from M.H. Chapin, M. Maunder, and USFWS (1996).
1. Survey ex situ holdings and conduct molecular fingerprinting.
2. Establish secure ex situ stocks with full founder representation.
3. Develop proper horticultural protocols and pest management for G. hillebrandii.
Recommendations derived from M.H. Chapin and M. Maunder.
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