Support for the Conservation of Endemic Pacific Palms Through Ex Situ Collections at the National Tropical Botanical Garden (NTBG), Hawaii, U.S.A
Volume 3 Number 6 - June 2001
Melany H Chapin, David H Lorence, Steve Perlman and K.R Wood
The National Tropical Botanical Garden (NTBG), Kauai, Hawaii began developing a palm collection from its inception in 1970. The NTBG was chartered by Congress in 1964 as a privately supported research and education institution. It encompasses more than 1,600 acres in four gardens and three preserves in Hawaii and one garden in Florida. Recent collecting expeditions have enhanced this collection with palms from New Caledonia, Kosrae, Pohnpei, Palau, and the Marquesas. NTBG is developing a conservation collection of the endemic genus Pritchardia. The living palm collections are actively used for research, conservation, education, and pleasure. Future plans include the strategic addition of species that are now under-represented or not represented at all.
Palms are among the important economically valuable plant families to human kind, yet this highly diverse group is both understudied and threatened. The tropical climate of Hawaii allows a great majority of palm species from all over the world to grow at the NTBG sites. Being situated in the United States tropics affords opportunities for developing an extensive palm collection that will be protected for future generations. Today the palm collection includes over 200 species of palm and is still growing.
The continued acquisition of palm species is an important part of developing NTBG's collections. In recent years several expeditions to Micronesia, New Caledonia, and the Marquesas have added very unusual, rare and interesting palms to NTBG's collections. The NTBG obtains the necessary botanical collecting permits from local and regional authorities and strictly complies with all national and international regulations.
A taxonomic research interest in the Micronesian flora has generated several NTBG collecting trips to Kosrae and Pohnpei in the Federated States of Micronesia (FSM) and one to the Republic of Palau (Belau). Micronesian palms collected on these trips include Nypa fruticans from Kosrae, Clinostigma ponapensis, Metroxylon amicarum and Ptychococcus ledermannianus from Pohnpei. Palms from Palau include Gulubia palauensis restricted to the upraised coral rock islands, Heterospathe elata var. palauensis, Pinanga insignis, and Ptychosperma palauensis. The Gulubia sp. is threatened by introduced cockatoos which eat the palm's heart, killing the plant.
New Caledonia has a unique and diverse palm flora (Hodel and Pintaud, 1998. The Palms of New Caledonia Allen Press, Lawrence, Kansas, USA.) and we were permitted to collect taxa such as Actinokentia divaricata, Basselinia gracilis and B. pancheri, Burretiokentia vieillardii, Campecarpus fulcitus, Cyphokentia macrostachya, and Cyphosperma balansae.
Collaboration with the Ministry of the Environment in French Polynesia has resulted in several joint collecting trips to the remote Marquesas Islands. In 1997 seed collections were made from nine of the ten individuals of the only known population of the rare Pelagodoxa henryana in Taipivai Valley on Nuku Hiva island. Today plants are thriving in ex situ collections in NTBG.
The living palm collections of NTBG are used for research and education. They represent an excellent research laboratory because all plants are accessioned with the origin and collector of each plant documented. For example, a phenological study was conducted on eight species of palms from different regions of the world (Chapin 1999). Currently, research is being conducted on palm flower and fruit ontogeny and their taxonomic implications. Anatomical, developmental, and histological studies are all easily conducted on fresh samples taken directly from the living palm trees. Examinations requiring destructive sampling of material such as palm fruits are readily carried out because there is usually an abundance of fruits or flowers available until completion of the study. For example, the highly threatened Marquesan palm, Pelagodoxa henryana, fruits almost continuously in Lawai Valley. Examination of the fruits involved dissecting them into pieces, testing them for floatation, measuring and weighing various parts, and performing histochemical tests on tissues shaved off of the fruit. In the wild, using such a highly threatened palm for these purposes would be unthinkable. However, using a garden's ex situ collection allows for further understanding of its natural history and biology without further threatening its wild status.
The Hawaiian archipelago is a hot spot for rare and threatened plants with the world's highest level of endemism, ca. 89% at the species level. Named in honor of William T. Pritchard, a 19th century British consul in the Fiji Islands (Wagner et al. 1990), Pritchardia is a genus of about 27 species found in Hawaii, Fiji, Cook Islands, Tonga, and the Tuamotus. There are now thought to be 22 species in the Hawaiian Archipelago, and each species is confined to a single island.
It is NTBG's goal to create a comprehensive conservation collection of Pritchardia. This may include as many as 50 trees per species to ensure genetic representation of surviving populations. NTBG currently has 24 species of Pritchardia in its collection and will continue to collect, making an effort to represent the entire genus (Table 1).
Table 1. Pritchardia species in NTBG living collections.
|Taxon||Island ||USFWS Status|
|P. affinis||Hawaii ||Endangered|
|P. beccariana||Hawaii |
| P. forbesiana ||Maui||Species of Concern (SOC)|
|P. glabrata||Maui ||SOC|
| P. hardyi ||Kauai||Candidate for Listing (c)|
| P. lanaiensis ||Lanai||SOC|
| P. limahuliensis ||Kauai||SOC|
| P. lowreyana ||Molokai|
| P. martii ||Oahu|
|P. napaliensis||Kauai ||Endangered |
| P. pacifica||Tonga|
| P. perlmanii ||Kauai||SOC |
| P. remota ||Nihoa ||Endangered|
| P. schattaueri ||Hawaii ||Endangered |
| P. thurstonii ||Fiji |
| P. viscosa ||Kauai||Endangered|
Pacific palm conservation activities are well underway at NTBG. For example, like many island endemic species, the endemic Pritchardia of Hawaii face the problems of grazing animals reducing the success of seedlings, predation on fruit by introduced rats, non-native invasive weeds displacing native seedlings, and other habitat degradation impacts. Additional threats to certain species include vandalism and unauthorized collecting of fruits and seedlings. Active research and monitoring of Pritchardia population status is being carried out by NTBG staff. Development of exclosures in the wild with the application of rat poison and rat guards to stop predation of fruit offers the threatened populations a chance at regeneration which they previously had lost. Both living and vouchered representation of individuals and populations are actively in progress. To date, the NTBG herbarium houses over 176 vouchers representing 25 species of endemic and Pacific island Pritchardia. Twenty one ancillary pickled collections of flowers or fruits of 19 species. Desiccated leaf samples in silica gel for molecular research include 18 samples of 12 species. Equally important, the living gene bank of Pritchardia collections includes seedlings germinating in the nursery as well as trees over 25 years old that represent 24 taxa, 218 accessions, and 645 individual plants. Reintroduction to the wild has included planting Pritchardia napaliensis and P. limahuliensis at the NTBG Limahuli Preserve, which comprises 1,000 acres. Reintroduction efforts have also included collaborative efforts with other agencies and land managers.
NTBG currently holds among the most extensive living and vouchered collections of Pacific island palms, particularly the threatened species. We have the most extensive representation of the genus Pritchardia by individuals and populations as well as Pelagodoxa. Species targeted for future expeditions and exchanges include expansion of the existing Pacific island collections and members of the Phytelephantoideae, Geonomeae, Iriarteeae, Calameae, Lepidocaryeae, and Podococceae.
We recognize that palm conservation is best achieved in the country of origin and in direct collaboration with habitat managers. Using our garden resources is leading to a better understanding of the population genetics and through collaboration with land managers reintroduction and habitat restoration efforts are in progress. Work to conserve the threatened Pritchardia species act as a model of integrated conservation management that can be applied to other Pacific island species.
Appreciation is given to Mike Maunder for his comments and guidance with this manuscript.
Melany H. Chapin, David H. Lorence, Steve Perlman, and K.R. Wood
National Tropical Botanical Garden