Hawaiian tropical dry forests
Encyclopedia
The Hawaiian tropical dry forests are a tropical dry broadleaf forest
ecoregion
in the Hawaiian Islands
. They cover an area of 6600 km² (2,548.3 sq mi) on the leeward
side of the main islands and the summits of Niihau
and Kahoolawe
. These forests are either seasonal or sclerophyll
ous. Annual rainfall is less than 127 cm (50 in) and may be as low as 25 cm (9.8 in); the rainy season lasts from November to March. Dominant tree species include koa (Acacia koa), koaia (A. koaia
), akoko (Euphorbia spp.), ōhia lehua (Metrosideros polymorpha
), lonomea (Sapindus oahuensis
), māmane (Sophora chrysophylla), loulu (Pritchardia
spp.), lama (Diospyros sandwicensis
), olopua (Nestegis sandwicensis
), wiliwili
(Erythrina sandwicensis), and iliahi (Santalum
spp.). Endemic plant species in the dry forests include hau heleula (Kokia cookei
), uhiuhi (Caesalpinia kavaiensis
), and Gouania
spp. The Palila
(Loxioides bailleui), a Hawaiian honeycreeper
, is restricted to this type of habitat.
of Polynesians
, excluding the deliberate introduction of non-native species. Fossil
ized pollen
has shown that loulu (Pritchardia
spp.) forests with an understory of Ka palupalu o Kanaloa (Kanaloa kahoolawensis) and aalii (Dodonaea viscosa
) existed on the islands' leeward lowlands from at least before 1210 B.C. until 1565 A.D. Populations of loulu and aalii still exist in diminished form, while only two Ka palupalu o Kanaloa specimens have ever been seen in the wild.
Tropical and subtropical dry broadleaf forests
The tropical and subtropical dry broadleaf forest biome, also known as tropical dry forest, is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive several hundred centimeters of rain per year, they have long dry seasons...
ecoregion
Ecoregion
An ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area that is smaller than an ecozone and larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural...
in the Hawaiian Islands
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
. They cover an area of 6600 km² (2,548.3 sq mi) on the leeward
Windward and leeward
Windward is the direction upwind from the point of reference. Leeward is the direction downwind from the point of reference. The side of a ship that is towards the leeward is its lee side. If the vessel is heeling under the pressure of the wind, this will be the "lower side"...
side of the main islands and the summits of Niihau
Niihau
Niihau or Niihau is the seventh largest of the inhabited Hawaiian Islands in the U.S. state of Hawaii, having an area of . Niihau lies southwest of Kauai across the Kaulakahi Channel. Several intermittent playa lakes provide wetland habitats for the Hawaiian Coot, the Black-winged Stilt, and the...
and Kahoolawe
Kahoolawe
Kahoolawe is the smallest of the eight main volcanic islands in the Hawaiian Islands. Kahoolawe is located about seven miles southwest of Maui and also southeast of Lanai, and it is long by wide, with a total land area of . The highest point on Kahoolawe is the crater of Lua Makika at the...
. These forests are either seasonal or sclerophyll
Sclerophyll
Sclerophyll is the term for a type of vegetation that has hard leaves and short internodes . The word comes from the Greek sclero and phyllon ....
ous. Annual rainfall is less than 127 cm (50 in) and may be as low as 25 cm (9.8 in); the rainy season lasts from November to March. Dominant tree species include koa (Acacia koa), koaia (A. koaia
Acacia koaia
Acacia koaia, known as koaia or koaie in Hawaiian, is a tree in the pea family, Fabaceae, that is endemic to Hawaii. It is closely related to koa , and is sometimes considered to be the same species...
), akoko (Euphorbia spp.), ōhia lehua (Metrosideros polymorpha
Metrosideros polymorpha
The ōhia lehua is a species of flowering evergreen tree in the myrtle family, Myrtaceae, that is endemic to the six largest islands of Hawaii. It is a highly variable tree, being tall in favorable situations, and much smaller when growing in boggy soils or on basalt...
), lonomea (Sapindus oahuensis
Sapindus oahuensis
Sapindus oahuensis, commonly known as Āulu or Lonomea, is a species of soapberry that is endemic to Hawaii. It can be found in dry, coastal mesic, and mixed mesic forests at elevations of on the islands of Kauai and Oahu . Āulu reaches a height of and a trunk diameter of...
), māmane (Sophora chrysophylla), loulu (Pritchardia
Pritchardia
The genus Pritchardia consists of between 24-40 species of fan palms found on tropical Pacific Ocean islands in Fiji, Samoa, Tonga, Tuamotus, and Hawaii. The generic name honours William Thomas Pritchard , a British consul at Fiji.-Description:These palms vary in height, ranging from...
spp.), lama (Diospyros sandwicensis
Diospyros sandwicensis
Diospyros sandwicensis is a species of flowering tree in the ebony family, Ebenaceae, that is endemic to Hawaii. Its common name, Lama, also means enlightenment in Hawaiian. Lama is a small to medium-sized tree, with a height of and a trunk diameter of . It can be found in dry, coastal mesic,...
), olopua (Nestegis sandwicensis
Nestegis sandwicensis
Nestegis sandwicensis, commonly known as Olopua, is a species of flowering tree in the olive family, Oleaceae, that is endemic to Hawaii. It is found on all major islands at elevations of in coastal mesic and mixed mesic forests, and, especially, dry forests...
), wiliwili
Wiliwili
Wiliwili is a species of flowering tree in the pea family, Fabaceae that is endemic to the Hawaiian Islands. It is the only species of Erythrina that naturally occurs there. It is typically found in dry forests on leeward island slopes up to an elevation of .Wiliwili is occasionally seen in...
(Erythrina sandwicensis), and iliahi (Santalum
Santalum
Santalum is a genus of woody flowering plants, the best known and commercially valuable of which is the Indian Sandalwood tree, S. album. Members of the genus are trees or shrubs. Most are root parasites which photosynthesize their own food but tap the roots of other species for water and...
spp.). Endemic plant species in the dry forests include hau heleula (Kokia cookei
Kokia cookei
Kokia cookei is a small, deciduous tree commonly known as the kokio, Molokai treecotton, Cooke's kokio, or Molokai kokio. It is considered one of the rarest and most endangered plant species in the world. Even when first found in the 1860s, only three trees could be located. It was presumed extinct...
), uhiuhi (Caesalpinia kavaiensis
Caesalpinia kavaiensis
Caesalpinia kavaiensis is a rare species of flowering plant in the pea family, Fabaceae, that is endemic to Hawaii. Common names include Uhiuhi , Kāwau , and Kea . It is threatened by invasive species, particularly feral ungulates.-Description:C...
), and Gouania
Gouania
Gouania is a genus of flowering plants in the buckthorn family, Rhamnaceae. The 50 to 70 species it contains are native to tropical and subtropical regions of the world, including Africa, Madagascar, the Indian Ocean islands, southern Asia, the Americas and Hawaii. They are shrubs or lianas...
spp. The Palila
Palila
The Palila is a critically endangered finch-billed species of Hawaiian honeycreeper. It has a golden-yellow head and breast, with a light belly, gray back, and greenish wings and tail...
(Loxioides bailleui), a Hawaiian honeycreeper
Hawaiian honeycreeper
Hawaiian honeycreepers are small, passerine birds endemic to Hawaii. Some authorities still categorize this group as a family Drepanididae, but in recent years, most authorities consider them a subfamily, Drepanidinae, of Fringillidae, the finch family...
, is restricted to this type of habitat.
Prehistoric dry forests
The plant composition of Hawaii's dry forests has changed rather dramatically since the arrivalAncient Hawaii
Ancient Hawaii refers to the period of Hawaiian human history preceding the unification of the Kingdom of Hawaii by Kamehameha the Great in 1810. After being first settled by Polynesian long-distance navigators sometime between AD 300–800, a unique culture developed. Diversified agroforestry and...
of Polynesians
Polynesians
The Polynesian peoples is a grouping of various ethnic groups that speak Polynesian languages, a branch of the Oceanic languages within the Austronesian languages, and inhabit Polynesia. They number approximately 1,500,000 people...
, excluding the deliberate introduction of non-native species. Fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
ized pollen
Pollen
Pollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement from the stamens to the pistil of flowering plants or from the male cone to the...
has shown that loulu (Pritchardia
Pritchardia
The genus Pritchardia consists of between 24-40 species of fan palms found on tropical Pacific Ocean islands in Fiji, Samoa, Tonga, Tuamotus, and Hawaii. The generic name honours William Thomas Pritchard , a British consul at Fiji.-Description:These palms vary in height, ranging from...
spp.) forests with an understory of Ka palupalu o Kanaloa (Kanaloa kahoolawensis) and aalii (Dodonaea viscosa
Dodonaea viscosa
Dodonaea viscosa is a species of flowering plant in the soapberry family, Sapindaceae, that has a cosmopolitan distribution in tropical, subtropical and warm temperate regions of Africa, the Americas, southern Asia and Australasia.-Description:...
) existed on the islands' leeward lowlands from at least before 1210 B.C. until 1565 A.D. Populations of loulu and aalii still exist in diminished form, while only two Ka palupalu o Kanaloa specimens have ever been seen in the wild.
See also
- Oceania ecozoneOceania ecozoneOceania is one of the WWF ecozones, and unique in not including any continental land mass. The ecozone includes the Pacific Ocean islands of Micronesia, the Fijian Islands, and most of Polynesia...
- Tropical and subtropical dry broadleaf forestsTropical and subtropical dry broadleaf forestsThe tropical and subtropical dry broadleaf forest biome, also known as tropical dry forest, is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive several hundred centimeters of rain per year, they have long dry seasons...
- Hawaiian tropical rainforests
- Hawaiian tropical low shrublandsHawaiian tropical low shrublandsThe Hawaiian tropical low shrublands are a tropical savanna ecoregion in the Hawaiian Islands. These shrublands cover an area of in the leeward lowlands of the main islands and most of the smaller islands, including the Northwestern Hawaiian Islands. The ecoregion includes both grasslands and...
- Hawaiian tropical high shrublandsHawaiian tropical high shrublandsThe Hawaiian tropical high shrublands are a tropical savanna ecoregion in the Hawaiian Islands. They cover an area of on the upper slopes of the volcanoes Mauna Kea, Mauna Loa, Hualālai, and Haleakalā. It includes open shrublands, grasslands, and deserts...
- List of ecoregions in the United States (WWF)