Endangered Species in the Pacific Islands
Wahiawa Plant Cluster Recovery Plan
Kaua‘i has the highest levels of plants found only in the Hawaiian archipelago. One particularly interesting area is the Wahiawa Drainage Basin in the Lihu‘e-Koloa Forest Reserve, located in the Koloa District of southern Kaua‘i. Five endangered plant taxa found in the Wahiawa Drainage Basin on the island of Kaua‘i are included in this recovery plan.
These plants are primarily found in native wet Metrosideros forest surrounding the Wahiawa Bog on gravelly and silty clay soils between 2,033 to 2,100 feet (620 and 640 meters) elevation. Two of the five plants also occur in similar forest in the Waioli Stream Valley and Makaleha Mountains.
Invasion by alien plants is the greatest threat to all five species. Other threats include predation on seeds by insects and rats, rooting by feral pigs, erosion and the possible loss of native pollinators. The recovery plan details the life history, habitat, reasons for decline, and conservation efforts for each plant species.
Hesperomannia lydgatei -
Photo credit Dr. Lamoureux/University of Hawaii
Habitat & Distribution:
The Wahiawa Mountains are made up of mostly lowland wet Metrosideros forest and shrubland. The wet forest is best developed in valleys, and the shrubland occurs on windswept slopes and ridgetops. The Wahiawa Drainage Basin is characterized by rugged, mountainous terrain bounded on the north by Mount Kapalaoa, on the southeast by Mount Kahili, and Pu‘u Au‘uka on the southwest side.
The drainage basin is an important watershed and source of the Wahiawa Stream and the Alexander Reservoir owned by McBryde Sugar Company. The five plants covered in this recovery plan are scattered about the drainage basin.
Alien plants, such as the strawberry guava, pose the most severe threat to the Wahiawa, Waoili, and Makaleha ecosystems. Some other threats to the five plants in this recovery plan include feral animals, landslides and erosion, disease, and insect predation.
The populations in the Wahiawa Drainage Basin occur on privately owned land and are consequently not managed by the Federal or State, although all five species are protected by Federal and State laws. The current landowner has entered into an agreement with th Fish and Wildlife Service to fence the site.
Some seeds and/or plants of the Wahiawa cluster have been collected and propagated at numerous botanical gardens.
The objectives stated in the recovery plan are to stabilize existing populations, downlist to threatened status, and eventually, completely remove the Federal protective status. Much basic research on the life history and reproductive biology of all five species and protection from alien species needs to be conducted in order to reach the objectives.