Narrowly endemic to two adjacent peaks in the northern Waianae Mountains of Oahu. The three currently known populations contain a total of fewer than 40 plants. The primary threats to the species are feral pigs and alien plants.
Threats to A. trinerve include:
browsing by feral goats and pigs
invasion of habitat by the Florida prickly blackberry (Rubus argutus)
Trampling and collecting of A. trinerve by humans may also contribute to the decline of the population.
Number of populations: 3 (USFWS 2001)
Number of plants: 63 (USFWS 2001)
Seeds of A. trinerve have been studied by the Center for Conservation Research and Training (CCRT), the National Seed Storage Laboratory (NSSL), and the National Tropical Botanical Garden (NTBG). The results concluded that the seeds are orthodox, and can tolerate drying and freezing. The laboratory germination time ranged from 3 weeks to 12 months (Yoshinaga 2002).
Using allozymes, Weller et al. (1996) found no genetic diversity within sampled individuals of this taxon.
Forty to forty-five individuals of A. trinerve were outplanted in a fenced and managed area in the Mt. Kaala Natural Areas Reserve (NAR) in 1996. The plants are not doing very well, probably due to over-saturation and low pH in the soil. Over three hundred seedlings are growing at a mid-elevation nursery at the Nike missile site, and are also being propagated at the Lyon Arboretum, NTBG, and the Waimea Arboretum (USFWS 1998). The Nature Conservancy of Hawaii (TNCH) determined that fencing against feral pigs would not be feasible around smaller populations (USFWS 1998).
NTBG currently has ex situ holdings of numerous seeds in its seed bank, which represents all three populations. In addition, there are 10 plants that represent two out of the three populations growing in the nursery of the botanical garden. The species is in cultivation in a number of European botanic gardens derived from a Joseph Rock collection made in the 1950s. Seed from A. trinerve stock was repatriated in 1996 to Waimea Arboretum, Oahu, Hawaii (M. Maunder, pers comm. 2002).
IIn 2002, the U.S. Fish and Wildlife Service determined that a designation of critical habitat was prudent for this species. (USFWS 2002)
1. Construct enclosures to protect its population against feral pigs. Where fencing is not feasible, other methods such as snaring could be implemented.
2. Control competing alien-plant species around the three extant populations of A. trinerve.
3. Conduct pollination biology and seed dispersal studies.
4. Map the genetic diversity in the surviving populations of A. trinerve.
Recommendations derived from M.H. Chapin, M. Maunder, and USFWS (1998).
1. Establish cultivated stocks with full founder representation.
2. Development of proper horticultural protocols and pest management for A. trinerve.
3. Survey ex situ holdings and conduct molecular fingerprinting.
Recommendations derived from M.H. Chapin and M. Maunder.
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