Natural communities below 1,000 m (ca 3,000 ft) elevation, receiving less than 50 inches annual precipitation, or otherwise bearing prevailingly dry substrate conditions comprise the lowland dry system in the Hawaiian High Islands Ecoregion. This system is found on the islands of Hawai‘i, Moloka‘i, Lāna‘i, Kaho‘olawe, O‘ahu, and Kaua‘i, and is best developed on the leeward sides of the islands, for example, the Kona flank of Mauna Loa, the leeward flank of West Maui, the leeward side of East Moloka‘i, the north slopes Lāna‘i and Kaho‘olawe, the lower slopes of the Wai‘anae Mountains (O‘ahu), and the leeward slopes of Kaua‘i. It occurs typically below the lowland mesic system. There are a number of natural communities described within this system, including a variety of grasslands, shrublands, and forests. Biological diversity is low to moderate in this system, and specialized plants and animals occur there, such as pueo, the Hawaiian owl (Asio flammeus sandwichensis) and the rare Hawaiian tree cotton, hau hele ‘ula (Kokia spp.)

Many plants of the lowland dry system, such as this endemic tree cotton Kokia drynarioides are rare and endangered, threatened by loss of habitat, wildfire, feral ungulates, and invasive weeds.

Natural communities and species of this system are listed among nested targets via the appendices.



The distribution of the Lowland Dry System across the Hawaiian High Islands Ecoregion is depicted below:

The Lowland Dry System on O'ahu (red areas above) has been reduced by fire, weeds, and feral ungulates to small remnants on the leeward slopes of the Wai'anae conservation area.

The Lowland Dry System on Kaua'i (red areas above) has been reduced by fire, weeds, and feral ungulates to small remnants on the leeward slopes of the conservation area.

The Lowland Dry System in Hawai‘i includes a variety of grasslands, shrublands and woodlands, typically on leeward slopes.