The Elfin Forests of Kaua`i

The Elfin Forests of Kaua`i

Barbara Maxfield

Tucked away in the swirling mists high above its famous beaches and swaying palm trees are small patches of a unique and fragile Hawaiian biological community that few people even know exist: the montane bog. Here, `ohi`a (Metrosideros polymorpha) trees that reach 50 feet (15 meters) into the sky in Hawaiian rainforests often grow less than a foot tall (0.3 m), and a step in the wrong direction can plunge you into muck up to 10 feet (3 m) deep.

Although montane bogs can be found on five of the main Hawaiian Islands, some of the best examples are concentrated on the island of Kaua`i. Toward the summit of Mount Wai`ale`ale, often called the rainiest spot on Earth, where almost 40 feet (12 m) of rain falls every year, a series of bogs within the Alaka`i Swamp provides habitat for 40 flowering plant species. Thirty-five of these species are endemic to the Hawaiian Islands, and 16 are found only in the boggy areas of Kaua`i.

Mount Wai`ale`ale has long been held sacred as the source of the waters of life for the island of Kaua`i. Hawaiian legends tell of yearly treks by the ali`i nui (high chiefs), kahuna (priests), and their attendants from the lowlands to the most remote heiau or ceremonial site at the summit of Wai`ale`ale. There, they would pay tribute to their gods, thank them for the life-giving waters provided during the past year, and ask that the waters continue in the coming year.

Along the way, they would collect plants and bird feathers to place as offerings to their ancient gods, and to use in the ceremonial robes and headpieces of the ali`i. Just as these ancient Hawaiians revered the Alaka`i for its plants, insects, and birds, the scientists of today make the long journey up the mountain to study the area and seek ways to protect it.

Formation of the Bogs

Famous for its steep surrounding cliffs and abundant waterfalls, the Alaka`i Swamp itself is actually rather flat. Lava that was once part of Mount Wai`ale`ale’s caldera eroded to create a concrete-like layer of soil that holds the rainfall. As plants dropped their leaves, a thick layer of wet, mucky soil developed, creating bogs that act as immense sponges to absorb the heavy rains. Over millions of years, plants evolved unique adaptions to tolerate the very wet and acidic conditions of the Alaka`i.

Grasses, sedges, clubmosses, ferns, and `ohi`a dominate these bogs, but unique species of flowering violets, orchids, primroses, geraniums, lilies, and daisies also are found there. In some cases, only remnant populations of these plants are scattered in Wai`ale`ale’s bogs, some with fewer than 20 individuals. Two plant species, `ale (Plantago princeps) and the orchid Plantanthera holochila, are listed as endangered species, and seven others are being monitored as candidates for listing or as species of concern.

Threats to the Fragile Habitat

After millions of years of slow and natural formation, the bogs have seen rapid changes in recent years. Despite the remoteness and harsh conditions of the Alaka`i, a variety of alien species, including humans, now threaten its fragile ecosystems.

By far the most threatening invader is the feral pig (Sus scrofa). In the bogs, they uproot vegetative cover searching for invertebrates and plant material, trample plants and seedlings, and disperse alien weed species. Feral pigs selectively eat certain native plants, sometimes extirpating rare species and frequently changing the composition of the bog.

The bogs of the Alaka`i have had relatively few invasions, and most are concentrated in highly disturbed areas. A small reed, Juncus planifolius, is the most common invader; others are beardgrass (Schizachyrium condensatum) and prickly Florida blackberry (Rubus argutus).

Humans also have played a role in disturbing the delicate bog ecosystems. For decades, hikers have trampled native plants growing along the Alaka`i Swamp Trail. Once the vegetative “crust” of the bog is broken, damage spreads quickly, and large, muddy wallows develop. Weed seeds also can be introduced and spread by hikers’ boots.

Protecting the Elfin Forests

The first major step taken to protect these unique bog ecosystems was a cooperative effort led by the State of Hawai`i’s Department of Land and Natural Resources and carried out by volunteers. A boardwalk over the old Alaka`i Swamp Trail is almost complete, enabling visitors to experience the forest with minor impacts.

In 1996, the Fish and Wildlife Service worked with the State and Wellington Fencing Company to exclude feral pigs from approximately 100 acres (40 hectares) of the montane bog. Nine rare plant species were protected by the fencing, including at least two, Astelia waialealae and Geranium kauaiense, that are candidates for listing under the Endangered Species Act.

Although building fences can be controversial in Hawaii, we took extra care on this project not to impact hunters, whose efforts are the most effective means currently available to control feral pigs and goats (Capra hircus) on Kaua`i. Hunters joined with us in determining the appropriate location of fencelines and helped us design gates into fencelines to ensure appropriate human access, including a path to a culturally important heiau (a pre-Christian place of worship).

Stuart Wellington, owner of the Wellington Fence Company, is a hunter himself and provided valuable expertise as well as an excellent means of communication with the local hunters. He takes pride in the fact that his company has helped protect these unique bogs and their rare plants for future generations.

We also worked with the National Tropical Botanical Garden to fund a videotape that has run repeatedly on public television channels on Kaua`i. It also has been used in Hawaiian classrooms to tell the story of these elfin forests and their importance to Kaua`i.

While it is a little early to see extensive improvements in these centuries-old communities, biologists are encouraged that the first bog fenced for protection is showing regrowth. In May 1998, they saw for the first time in years the flower of Astelia waialealae, a species known only from three bogs within the Alaka`i Swamp and numbering only 35 individual plants. In the past, feral pigs had repeatedly eaten it almost to the ground.

Kaua`i’s elfin forests indeed have a magical spirit about them, for one cannot visit without feeling awe for their ability to adapt and thrive in such harsh conditions. It is now our job to ensure that they survive and flourish in this, the wettest place on Earth.

Barbara A. Maxfield is a Public Information Specialist with the FWS Pacific Islands Ecosystem Office in Honolulu, Hawaii.

COPYRIGHT 1998 U.S. Fish & Wildlife Service

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