Hakalau Forest NWR contains some of the finest remaining stands of native montane wet forest in Hawaii. The slopes below feet receive very high rainfall - annually. Bogs, fern patches, and scrubby forest dominate this area, which is dissected by numerous deep gulches. Rainfall decreases to about at elevations above, where majestic koa and red-blossomed ōhia lehua trees form a closed-canopy forest. Further upslope, above, rainfall decreases to or less and native forest merges into abandoned pastureland where alien grasses and weeds, introduced as forage for cattle, are the dominant vegetation. Since 1989, over 400,000 koa, ōhia, and other native plants have been planted in this area as part of the refuge's reforestation program. The Pua Akala Cabin, located within the refuge, was nominated to the National Register of Historic Places in August 2008. In 1985, on the eastern slope of Mauna Kea were established as the Hakalau Forest Unit. In 1997, the Fish and Wildlife Service purchased an additional of land to create the Kona Forest Unit of Hakalau Forest NWR. The Kona Forest Unit includes lands within the Hookena and Kalahiki land divisions on the western slopes of Mauna Loa, at elevations of. One of the primary purposes for the creation of this unit was to protect the habitat of the alalā, which is now extinct in the wild. The Kona Forest Unit is located about south of Kailua-Kona, coordinates. The Kona Forest district is somewhat drier than the Hakalau Unit.
Wildlife and habitat
Much of Hawaii's native lowland habitat was degraded following the Polynesians’ arrival over a thousand years ago. In the late 18th century, cattle, goats, and European pigs were released into the forests, and hundreds of additional alien plants, animals, and insects have subsequently been introduced. Most lowland plants seen today like the orchid, ginger, and plumeria are aliens or nonnative. Introduced animals such as mosquitoes, wasps, small Asian mongooses, cats, and rats have also harmed Hawaiian habitat and native species. Grazing pressure by cattle and pigs has resulted in the replacement of Hawaiian plants by more competitive alien grasses and shrubs within the upper portions of Hakalau Forest. Below this pasture area, the native tree canopy is still intact, but the native understory has been replaced by alien grasses, blackberry, banana poka, and English holly. The replacement process may have been accelerated by efforts to create more pasture land through bulldozing and burning, and by logging mature trees for timber and fence posts. Eight of the 14 native bird species occurring at Hakalau are endangered. Thirteen migratory bird species and 20 introduced species, including eight game birds, as well as the endangered opeapea also frequent the refuge. Twenty-nine rare plant species are known from the refuge and adjacent lands. Twelve are currently listed as endangered. Two endangered lobelias have fewer than five plants known to exist in the wild.
Recreation
Only the Upper Maulua Unit of Hakalau Forest National Wildlife is open to the public for wildlife-dependent activities such as hiking, bird watching and photography. All other units of the refuge are closed. Access to Upper Maulua is permitted on Saturdays, Sundays and holidays between sunrise and sunset. Every visitor to Upper Maulua is required to have a reservation. Reservations can be made by calling the Hakalau Forest NWR office at least one week prior to entry.
