Hawaiian tropical dry forests

Hawaiian tropical dry forests are a tropical dry broadleaf forest ecoregion in the Hawaiian Islands. They cover an area of on the leeward side of the main islands and the summits of Niihau and Kahoolawe. These forests are either seasonal or sclerophyllous. Annual rainfall is less than and may be as low as. The rainy season there lasts from November to March.
Dominant tree species include koa, koaia, akoko, ōhia lehua, lonomea, māmane, loulu, lama, olopua, wiliwili, ohe makai, and iliahi. Endemic plant species include hau heleula, uhiuhi, and Gouania spp. The palila, a Hawaiian honeycreeper, is restricted to this habitat type.

Prehistoric dry forests

The forests' plant composition changed following the arrival of Polynesians, even excluding the deliberate introduction of non-native species. Fossilized pollen has shown that loulu forests with an understory of Ka palupalu o Kanaloa and aalii existed on the islands' leeward lowlands from at least before 1210 B.C. until 1565 A.D. Populations of loulu and aalii remain in diminished form, while only two Ka palupalu o Kanaloa specimens have ever been seen in the wild.

Maui

The Auwahi Dryland Forest Restoration Project recreated a substantial forest with exclusively native species from invasive Kukui grasses on the slopes of Haleakala on the island of Maui.