THE U.S. Fish and Wildlife Service, in a media release, says it has released a plan identifying actions needed to recover two endangered plants found in the Mariana Islands. The two plant species — Nesogenes rotensis and Osmoxylon mariannense — are found only on the island of Rota in the Commonwealth of the Northern Mariana Islands.
The interim goal of the plan is to control threats and increase population sizes and geographic distribution of the two species in order to downlist the plants from endangered to threatened status. The ultimate goal is to remove the two plants from the federal list of endangered and threatened species.
“Both species are found in unique limestone habitats on the island of Rota and have few individuals left,” said Patrick Leonard, field supervisor for the Fish and Wildlife Service in the Pacific Islands. “The recovery actions outlined in this plan will not only benefit these two rare plants and their habitats, but are also expected to benefit the endangered Rota bridled white-eye, the endangered plant Serianthes nelsonii and the threatened Mariana fruit bat through habitat protection and restoration in the Sabana region of Rota.”
Nesogenes rotensis is found on raised limestone flats in nonforested coastal strand habitat and has only two known populations of 15-20 plants each. Osmoxylon mariannense has 10 known individuals scattered throughout the plateau of western Rota known as the Sabana.
The final recovery plan states that the species will be considered for downlisting when the following criteria are achieved and maintained for a minimum of 10 consecutive years:
• A total of two populations of each species are naturally reproducing and stable or increasing in numbers. Each population of Nesogenes rotensis must consist of at least 300 mature, reproducing individuals, and each population of Osmoxylon mariannense must have at least 100 mature reproducing individuals.
• Sufficient habitat is protected and managed to achieve the identified population goals.
• Management and control of nonnative species by local, Commonwealth and federal authorities are demonstrated to be successful to achieve the identified population goals.
Delisting requirements for each species include the same criteria, but require four naturally reproducing and stable or increasing populations for a period of 10 consecutive years for each species.
These two plant species were federally listed as endangered in 2004 primarily due to human activities that alter native vegetation and habitat, such as agriculture; ranching; nonnative plant and animal introductions; resort and beach park development in the coastal habitat of Nesogenes rotensis; and road construction and maintenance in the Sabana habitat of Osmoxylon mariannense. The extremely low population numbers and limited distributions of these two species also make them subject to extinction from naturally occurring events such as typhoons.
Nesogenes rotensis is an herbaceous plant in the Verbena family with small, coarsely toothed leaves and small white flowers. Osmoxylon mariannense is a spindly, soft-wooded tree in the Ginseng family that can reach 33 feet in height.
Availability of the recovery plan was announced in the Federal Register on May 3, 2007. Copies of the recovery plan are available through the Fish and Wildlife Service’s Web site at http://www.fws.gov/pacificislands/ or by calling the Fish and Wildlife Service’s Honolulu office at 808 792 9400.