This species was discovered in 1909 in the district of North Kona on the island of Hawaii, when about a dozen trees were found. The last known wild tree died in the 1990's. Descendants of the wild trees remain in cultivation, and some have been outplanted within the former range of the species. The species' forest habitat has been grazed since the 1800's. Threats to the outplanted individuals include cattle, goats, pigs, fire, and alien plants.
Threats to H. hualalaiensis include:
degradation of habitat by domestic and feral cattle, feral pigs and sheep
flower and seed predation by rats
competition from invasive introduced plants such as Lantana camara (lantana)
Number of Populations: 0 (USFWS 2001)
Number of Plants: 22 (USFWS 2001)
In the 1970's, a number of individuals studied the effects of hybridization between this species the closely related, also endangered, Hibiscadelphus giffardianus. (Baker & Allen 1976, Baker & Allen 1977, Carr & Baker 1977, Degener & Degener 1977) These two species did not naturally occur together, but had been planted near each other in Hawaii Volcanoes National Park during early conservation efforts. It was eventually determined that this situation resulted in hybridization between the two species. The decision was made to remove H. hualalaiensis from the park in order to maintain the genetic integrity of both species. Today, both of these species are maintained in cultivated settings.
Small areas have been fenced around the two outplanted populations to exclude livestock and feral ungulates at the Puu Waawaa Wildlife Sanctuary and the Kokia Sanctuary in Kawaihae. No other specific measures have been taken.
Volcano Rare Plant Facility (VRPF) has 10 plants in their nursery and Waimea Falls Park (WFP) has 4 plants; however they are doing poorly. The National Tropical Botanical Garden (NTBG) currently has ex situ holdings of 172 seeds in its seed bank, and 14 individuals in the botanical garden (USFWS 1998).
1. Outplant new populations in areas managed. Prior to outplanting, the sites should be fenced, free of weeds and free of rats and feral ungulates.
2. Reduce threats from rodent predation. Diphacinone bait block are successfully being used but a more broad scale method such as aerial dispersal of rodenticide should be considered.
3. Protect populations from fire. Steps should be taken to prevent the extirpation of the outplanted populations and future outplanting from wildfires. Removing alien grasses may help to reduce the fuel load.
4. Conduct pollination biology, seed dispersal mechanism, and molecular phylogenetic studies on H. hualalaiensis.
5. Map genetic diversity in the surviving populations of H. hualalaiensis.
6. Test the influence of weeding and fencing on populations of H. hualalaiensis.
Recommendations derived from M.H. Chapin, M. Maunder, and USFWS (1998).
1. Establish secure ex situ stocks with full founder representation.
2. Develop proper horticultural protocols and pest management for H. hualalaiensis.
3. Survey ex situ holdings and conduct molecular fingerprinting.
Recommendations derived from M.H. Chapin and M. Maunder.
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