The Nature Conservancy - Biodiversity Buzzwords

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King Koa. This ancient native koa forest sheltering a profusion of life at Kona Hema Preserve is endemic to Hawai'i.

The Last Stand: The Vanishing Hawaiian Forest

cover of Last Stand This Conservancy-published booklet reports on the state of Hawaii's native forests. Click here to download pdfs of Last Stand now! (24 pages, 4.3 MB)

Silent Invasion

Find out more about invasive species and why stopping the influx of new pests and containing their spread is essential to Hawaii's future well-being.

By Samuel M. ‘Ohukani‘ōhi‘a Gon III
Senior Scientist and Cultural Advisor

"Today, protecting highly restricted endemic species within alien-dominated habitats poses one of the greatest challenges to resource managers mandated to maintain indigenous diversity."

Did reading this sentence just make your brow furrow, your eyes glaze over? Did you read it more than once, to fully grasp the weighty ideas it contains? (Be honest, now.)

If you did, don’t feel unintelligent. You’re not, and you’re not alone, either. You’ve just been “bio-buzzed.”

Whether you're working with biologists dealing with the diversity of life on Earth, or dedicated to protecting our rich natural heritage here in Hawai‘i, you hear lots of terms dealing with the fate of rare native plants, animals and ecosystems. It's important to understand what these buzzwords mean, and how they relate to the complex picture of conservation work in Hawai‘i.

One important set of terms deals with the global range of a particular species or ecosystem. In Hawai‘i, these terms are especially important, because most of our native plants and animals are restricted to the Hawaiian Islands, often to a single island, and sometimes to one or a few locations in a single mountain range!

When you find a plant growing in Hawai‘i, it might be one of two general things: native or alien.

native: occurring naturally in a place; not introduced purposely or accidentally by humans.
alien: introduced by humans purposely or accidentally to a place; not native.

A plant or animal called native to Hawai‘i is one found naturally here. In fact, most of our native species occur only in Hawai‘i, and nowhere else in the world!

If a species is native to Hawai‘i, there are two categories to consider: indigenous and endemic. The first is broad, the second more restricted:

indigenous: naturally occurring in an area (and potentially occurring elsewhere).
endemic: restricted to an area.

Thus, the beach naupaka, a common native coastal plant, is called indigenous to Hawai‘i, because it occurs naturally here, but is also found naturally in many other tropical Pacific locations. In contrast, koa trees are endemic to the Hawaiian Archipelago, and are by definition found nowhere else on Earth. On a global scale, the koa can be considered a fairly restricted endemic species, since it is limited to a single island system. However, there are much more highly restricted endemics in Hawai‘i, such as some rare tree snail species on O‘ahu, known only from a single ridge within the Ko‘olau Mountain Range.

Rats are an invasive alien species whose presence harms native ecosystems.

In contrast to native, an alien plant or animal is alien no matter how many years its been here. Many of Hawaii's common backcountry weeds have been here for well over a century, and have established self-sustaining populations. Such species are called naturalized aliens, but they are still not native.

Many introduced species are beneficial, so it is important to note that not all alien species are harmful. The vast majority can't even survive or reproduce without human care, and of those that are able to naturalize, relatively few can spread within native-dominated ecosystems.

Not All Aliens are Invasive

Much of the vegetation we see below 2000 feet elevation on O‘ahu is dominated by these naturalized alien plants. One special category of naturalized alien plants is represented by those species brought in by the first Polynesian ancestors of the Hawaiian people. Plants such as ti, kukui, honohono, milo and coconuts are among these Polynesian introductions.

Invasive, forest-choking miconia

But of the thousands of alien plants found in Hawai‘i perhaps 150 are on the list of invasive alien species: those that can readily invade even undisturbed native ecosystems, and once entrenched, actually modify those ecosystems significantly, changing nutrient, light, or fire conditions, accelerating the decline of native species, and encouraging the encroachment of other alien pests such as rodents and harmful insects.

Once upon a time, Oahu's endemic tree snails were abundant in alien-dominated vegetation in valleys such as Mānoa or Nu‘uanu, living on Polynesian introductions such as ti and bananas. Alien pests such as rats and predatory snails have put an end to those friendlier times for our native species, many of which have been driven into extinction. We at the Conservancy continually battle these threats in our protection efforts.

Today, protecting highly restricted endemic species within alien-dominated habitats poses one of the greatest challenges to resource managers mandated to maintain indigenous diversity.

And now we all know what that means!

Nature picture credits (top to bottom, left to right): Photo © Phil Spalding III (koa tree, Kona Hema Preserve); © Jack Jeffrey (rat eating native bird eggs); © Phil Spalding III (miconia calvescens, Hana, Maui).