Name:
Metrosideros polymorpha - Acacia koa / Freycinetia arborea Lowland Rainforest Group
Reference:
NatureServe Biotics 2019
Description:
This lowland rainforest group occurs on all the main Hawaiian Islands except Ni`ihau and Kaho`olawe. Lowland wet forests are thought to have been the predominant original vegetation of the windward lowlands on the larger main islands. The canopy is dominated by <i>Metrosideros polymorpha</i> or, in some forests, by <i>Acacia koa</i> where it attains heights up to 40 m. On some islands, this group forms a distinct belt above <i>Acacia</i>-dominated mesic forest. Diversity in the lowland rainforest is high, and <i>Metrosideros</i> and <i>Acacia</i> at times form an emergent layer over a diverse layer of native trees and an understory of native ferns, herbs, shrubs and vines. Important taxa in this rainforest group include <i>Alyxia stellata, Antidesma platyphyllum, Broussaisia arguta, Cheirodendron</i> spp., <i>Cibotium</i> spp., <i>Coprosma</i> spp., <i>Cyrtandra</i> spp., <i>Dicranopteris linearis, Diospyros sandwicensis, Freycinetia arborea, Hedyotis</i> spp., <i>Ilex anomala, Korthalsella</i> spp., <i>Machaerina</i> spp., <i>Melicope</i> spp., <i>Myrsine</i> spp., <i>Peperomia</i> spp., <i>Pittosporum</i> spp., <i>Psychotria</i> spp., <i>Sadleria</i> spp., <i>Smilax melastomifolia</i>, and in some areas <i>Pritchardia</i> spp. Native trees that occur in the understory include <i>Psychotria hawaiiensis</i> and <i>Antidesma platyphyllum</i>. The endemic liana <i>Freycinetia arborea</i> is often abundant in these forests. Species that act as epiphytes include <i>Astelia menziesiana, Peperomia</i> spp., <i>Adenophorus</i> spp., <i>Huperzia</i> spp., and <i>Elaphoglossum</i> spp.<br /><br />In the upper reaches of the lowland ohi`a forest on the island of Hawai`i, the understory is dominated by tree ferns or <i>Cibotium</i> spp. which form a distinct closed layer beneath the trees. A more open <i>Metrosideros</i> forest with other scattered native trees and a dense ground cover of the indigenous mat-forming <i>Dicranopteris linearis</i> and other related ferns (<i>Diplopterygium pinnatum, Sticherus owhyensis</i>) is seen on steep ridges and valley walls of Kaua`i, O`ahu, Moloka`i, Maui, and the Kohola Mountains of Hawai`i. <i>Freycinetia arborea, Antidesma platyphyllum, Perrottetia</i>, and <i>Bobea</i> spp. are constituents restricted largely to the lowland zone. The group typically occurs on windward slopes high enough to intercept orographic rainfall resulting from rising moist tradewind air, but also occurs in a relatively narrow high precipitation band on the leeward side of the Big Island resulting from Kona storms. Soils vary throughout the island chain, from gray acidic clays on older islands to thin organic mucks over lava flows and ash beds on Hawai`i.
Accession Code:
urn:lsid:vegbank.org:commConcept:40119-{2E10DB77-C516-4BE9-A318-91BD289F307F}
Plot-observations of this Community Concept:
0
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