Diplazium molokaiense

No Common Name

Description

Diplazium molokaiense, a member of the wood fern family (Dryopteridaceae), has a short prostrate rhizome. The green or straw-colored leaf stalks are 6-8 in (15.2-20.3 cm) long. The thin-textured and ovate-oblong frond is 6-20 in (15.2-50.8 cm) long, 4-6 in (10.2-15.2 cm) wide, truncate at the base, and pinnate with a pinnatifid apex. The sori are 0.3-0.5 in (0.8-1.3 cm) long and lie alongside the side veins of the pinnae. D. molokaiense can be distinguished from other species of Diplazium in the Hawaiian Islands by venation pattern, the length and arrangement of the sori, frond shape, and the degree of dissection of the frond.

Habitat

Recently known populations of D. molokaiense were observed at elevations between 2,800 and 5,500 ft (853.4 and 1,676.4 m) in lowland to montane habitat, including montane mesic 'Ohi'a/Koa forest.

Distribution

D. molokaiense was found historically at Kaholuamano on Kauai; Makaleha and Schofield Barracks on Oahu; Kalae, Kaluaaha, Mapulehu, and the Wailau Trail on Molokai; Mahana Valley and Kaiholena on Lanai; Ainahou Valley and Maliko Gulch on East Maui; and Wailuku Valley and Waikapu on West Maui. However, during the last two decades of the twentieth century, only one population of one individual was recorded; occuring on East Maui at Waiopai Gulch on Department of Hawaiian Home Lands property. A population of ferns on the Makawao side of East Maui may belong to this species, but the population's identity needs to be confirmed.

Threats

The primary threats to D. molokaiense are habitat degradation by feral goats, cattle, and pigs; competition with alien plants; and stochastic extinction. On Maui, large populations of feral goats persist on the south slope of Haleakala outside of Haleakala National Park, where they threaten the population ofD. molokaiense at Waiopai. The habitat of this fern has been reduced to small remnants of its former territory by goat activities. Cattle ranching was once the primary economic activity on the west and southwest slopes of East Maui, where the population ofD. molokaiense can be found. Although this area is no longer actively ranched, feral cattle threaten this species. Axis deer are also moving into the area.

Conservation and Recovery

The Living Indigenous Forest Ecosystems organization is working to restore the native vegetation of Kahikinui Forest and at the turn of the twenty-first century began fencing a portion of the forest reserve. Although the Waiopai Gulch population ofD. molokaiense is not within the section of forest being fenced, forest management work in the area should benefit the habitat of this fern. The priority recovery actions for this plant are fencing and removal of hoofed mammals from its habitat, control of competing alien plant species, cultivated propagation, and protection and enhancement of the wild population. Surveys are also needed to locate new populations of this fern and determine the status of occurrences that have not been seen since the late 1970s. The exclosure built by Living Indigenous Forest Ecosysems at Kahikinui Forest might be a good location for establishing new populations of D. molokaiense.

Contact

U. S. Fish and Wildlife Service
Regional Office of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
(503) 231-6121
http://pacific.fws.gov/

Reference

U. S. Fish and Wildlife Service. 1998. "Recovery Plan for Four Species of Hawaiian Ferns." U. S. Fish and Wildlife Service, Portland, Oregon.