By Eric Sprague, Director of Forest Conservation
For tens of millions of years, the Hawaiian Islands have been isolated from the rest of the world by vast stretches of Pacific Ocean, with the nearest continent 2,000 miles away. Because of this isolation, the Hawaiian Islands developed unique forest ecosystems that resulted in an incredible amount of biodiversity. With 90 percent of land-based plants and animals occurring nowhere else, the Islands have the highest percentage of endemic species in the world.
The signature tree of the Hawaiian Islands is a great example of Hawaiʻi’s diversity. The early ancestor of the ʻōhiʻa lehua tree quickly adapted to the varied habitats present on the Islands. Today, the ʻōhiʻa lehua can be found at sea level as one of the first colonizers on new lava flows and at the limit where trees can survive at over 8,000 feet above sea level. It can also be found in poor soils at the edges of bogs and in the wettest rainforests in the world. In these various environments, the tree can occur as a shrub or a 100-foot-tall tree. The ʻōhiʻa lehua has adapted so well that it is the most abundant and widespread tree making up 80 percent of Hawaiʻi’s forests.
The ‘i’iwi, or scarlet honeycreeper, has seen the steepest decline of any honeycreeper in recent decades. Credit: Caleb Slemmons
The nectar-producing flowers of the ʻōhiʻa lehua are favored by many species among the spectacularly diverse Hawaiian honeycreepers. The ancestors of these birds were likely from a single species that, like the ʻōhiʻa lehua, quickly adapted to exploit different habitats, which produced great diversity in bill size, bill shape and color. For example, the Maui parrotbill (kiwikiu) uses its parrot-like bill to strip bark and break branches to search for insect larvae and the scarlet honeycreeper (ʻiʻiwi) uses its long decurved bill to feed on nectar.
Yet, this spectacularly unique and diverse flora and fauna is under threat. Within the last few hundred years, the loss of habitat and widespread distribution of nonnative plants and animals have wreaked havoc on Hawaiian forests and the wildlife that call them home, making Hawaiʻi the “extinction capital of the world.” While comprising less than one percent of the Unites States’ land mass, 40 percent of all plant and animals listed as threatened or endangered in the U.S. are found in Hawaiʻi.
The status of Hawaiian honeycreepers and the ʻōhiʻa lehua are tied to these trends. Today, less than half of the 51 formerly known honeycreepers are still found in Hawaiian forests. There are only around 500 Maui parrotbills remaining and the scarlet honeycreeper has seen the steepest decline of any honeycreeper in recent decades. Rapid ʻŌhiʻa Death is a new fungal disease that can kill trees within days. The loss of this tree will transform Hawaiian forests.
Hawaiian forests, host to a variety of endemic plant and animal species, face multiple threats. Credit: Bernard Spragg
Restoration efforts through our Wildlands for Wildlife initiative are aimed to help these evolutionary wonders recover and thrive in Hawaiian forests once again. This year, American Forests is partnering with the Hawaiian Forest Institute to restore native forest by removing invasive weeds and planting native plants at the Keauhou Bird Conservation Center’s Discovery Forest. The Center and Discovery Forest are part of a restoration and education project, which seeks to engage young people in forest stewardship learning opportunities and forge connections between science and native Hawaiian culture. The connection between forests and people will be critical to maintaining support for restoration.