Lana'i's Native Plants, Birds Succumb to Onslaught of Invaders

posted in: February 1994 | 0

In ancient times, flightless geese, ducks, ibises and rails roamed Lana’i’s extensive dryland forests. At the summit, a cloud forest dominated by ‘ohi’a lehua (Metrosideros collina) with an understory of ferns and many other native plants was home to at least eight species of native forest birds. Eagles, hawks and ravens soared above the trees. More than 40 species of land snails were found on Lana’i as recently as the late 19th century.1

The flightless birds are thought to have become extinct after the arrival of the first humans around 1,500 years ago. Most of the plants, snails, and forest birds survived until recent times. Today, however, many of those survivors are thought to be extinct or to be on the brink of extinction. Thirty-eight different plants found on Lana’i have been federally listed as endangered or threatened. Of those, five are found on no other island. One of the five (Phyllostegia glabra var. lanaiensis) may have already disappeared.

Since the early 1900s, four varieties of honeycreepers and the Lana’i thrush have become extinct. Today just one species of native forest bird – the apapane (Himatione sanguinea sanguinea Gmelin) – remains in the summit area.

The forest of ‘akoko (Euphorbia celastroides) in the Palawai Basin was destroyed by goats by 1970. More than a dozen native plants found on the island as late as 1935 had vanished by 1971; altogether, 70 of 345 recorded native plants on Lana’i had disappeared by 1992. The land snails have been all but wiped out.

Perhaps it is remarkable that anything has survived at all. By the end of the 19th century, some 50,000 sheep were running loose, along with a large but undetermined number of goats. The animals devoured the forests, which, because of the resulting erosion and soil loss, had little hope of recovery even after pigs, sheep and goats had been eradicated.

Today, the chief threat to what remains of Lana’i’s native plants comes from browsing, trampling, and antler-rubbing by the axis deer, introduced for hunting purposes. Rats have been known to eat the fruit of the federally endangered na’u (Gardenia brighamii), preventing its successful regeneration.

Last-Ditch Efforts

The best surviving remnant of Lana’i’s native dry lowland forest is found scattered over about 130 acres near Kanepu’u, a small hill on the island’s northwestern panhandle, five miles northwest of Lana’i City. Although the area has been degraded, some 45 taxa of native plants survive there, including the Hawaiian gardenia, a rare variety of sandalwood called `iliahi (Santalum freycinetianum var. lanaiense), and (perhaps) koki’o (Kokia drynarioides), all of which appear on the federal list of endangered species.

Recognition of Kanepu’u’s value can be traced back more than 80 years, when George Munro fenced several areas to keep out livestock. After Munro retired from the Lana’i Company in 1935, however, cattle returned to the area.

In 1956, the Conservation Council for Hawai’i studied the area and recommended it be given special protection. Twenty years later, Castle & Cooke erected three exclosures at Kanepu’u to keep deer out of especially sensitive areas.

In 1985, Hui Malama Pono O Lana’i, a group of volunteers, began to fence selected rare trees. Finally, in 1991, Castle & Cooke granted a permanent conservation easement over 590 acres of land at Kanepu’u to The Nature Conservancy of Hawai’i (whose current president is Thomas C. Leppert, head of the Lana’i Company, a subsidiary of Castle & Cooke).

The Nature Conservancy fenced seven tracts within the preserve and has driven the deer out of them. Long-term management plans call for weed eradication and reforestation with the native trees.

In 1992, the state Department of Land and Natural Resources approved the Nature Conservancy’s management plan for Kanepu’u for funds under the state’s Natural Area Partnership program. This provides 2-to-1 matching funds for carrying out the preserve’s management plan.

Long- Term Prospects

If Kanepu’u is restored, that will still leave more than 88,000 acres of Lana’i in fairly ravaged condition. Moreover, little is being done to manage Lana’ihale, the summit area that is the primary watershed for the island.

Robert Hobdy, a state forester, regards the island’s overall prospects for recovery as bleak:

“The prognosis for Lana’i’s native flora and fauna is not good,” Hobdy writes. “The agents that have brought about the present levels of decline are for the most part still present and continue to exert their influence. No reversal or even significant abatement of the present trend appears likely.

“Lana’i’s native ecosystems have suffered severe disintegration of their many interactive components and are experiencing what may be termed catastrophic collapse. What it may be possible to save will probably amount to no more than assemblages of the more vigorous and resistant remnants. Too little remains of these ecosystems for them to effect significant recoveries.”

1 Most of the information here is found in Robert Hobdy, “Loss of Biodiversity on the Island of Lana`i,” Pacific Science 47 (July 1993). Hobdy, a forester with the DLNR on Maui, is a Lana`i native. Additional information was compiled by Marjorie F.Y. Ziegler, “The Cultural Natural History of Kanepu`u, Lana`i, and its Potential for a Natural Area Preserve,” honors thesis (University of Hawai`i Department of Geography, 1986). Both Hobdy and Ziegler – and, indeed, virtually all others writing on Lana`i’s natural history – draw heavily from George C. Munro’s unpublished work, “The story of Lana`i.”

— Patricia Tummons

Volume 4, Number 8 February 1994

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