The ecoregion is exclusive to the US state of Hawaii and essentially occupies the intermediate belt (based on altitude and/or moisture) between the drier shrublands and moister forests. It occurs on all the main islands with the most extensive area occurring on the island of Hawaii. They are typical of the leeward (western) side of the main islands and include summit regions of the smaller islands.
On some of the islands, this ecoregion occurs down to the ocean edge but is more typically bordered coastward by Hawaiian Tropical Low Shrublands (OC0702), particularly on leeward slopes of the islands. The ecoregion merges into the Hawaiian Tropical Moist Forests (OC0106) either at higher elevations or on eastern windward slopes of the islands. On the island of Hawaii, part of this ecoregion merges directly into higher altitude Hawaii Tropical High Shrublands (OC0701).
Description of the Ecoregion
A detailed description of the ecoregion can be found at WWF’s site (the map above is a screen shot from that Wildfinder site). There may also be additional information to be found on this ecoregion’s page at Wikipedia.
As described by WWF, most native lowland forests of Hawaii are either seasonal or sclerophyllous to some degree, and more mesic transition forests occur where conditions are favorable. These transition forests include mixed mesic forests that often contain patches and elements of dry forest communities. Several shrubland, grassland, and herbaceous formations occur within this ecoregion. On most of the main islands (except Lanai) some of the ecoregion is coastal.
Birds of the Ecoregion
The extant endemic native species of Hawaii tend to occur in moist forests but some of them are perhaps partial to drier forests and would be characteristic of this ecoregion. One is probably the Palila (Psittirostra bailleui), an endangered Hawaiian finch of Hawaii island, which specializes on mamane trees that occur in dry forest habitats. WWF notes also that lower Hawaiian dry forest was habitat for species that are now extinct such as honeycreepers, flycatchers, and flightless rails.
The expected species of this ecoregion will be all of the species in the list for Hawaii (see under Hawaii Tropical Low Shrublands), with those partial to drier forest areas being the most characteristic.