This ecological site occurs on a variety of substrates in wet, warm regions of Hilo and Puna districts of the Island of Hawai`i. Plant communities evolved without the presence of large mammals or the regular occurrence of fires. The original forest plant community is now disturbed and fragmented due to fires, timber cutting, domestic and feral ungulate foraging, establishment of introduced pasture grasses, and alien species invasion. Most areas of this ecological site bear little resemblance to their original appearance. Vegetation on unmanaged lands consists of either forest dominated by alien species or shrubby grassland dominated by alien species under a regime of periodic fires.
This state represents the Historic Climax Plant Community. The general aspect is a forest with a tall (to about 80 feet), closed to open overstory of ohia trees, a secondary canopy of diverse trees species 25 to 40 feet tall, an open tree fern canopy 10 to 15 feet tall, and a diverse understory of shrubs and ferns. Vines are moderately abundant, particularly `ie`ie, both on the ground and on trees. Large bird’s nest ferns are common on trees and on the ground. The mid-canopy is dominated by pandanus trees near the coast; this species becomes less common with distance from the coast. Pandanus seems to be moderately invasive, and may be more common on previously disturbed sites or where it was encouraged by Hawaiians in the past. The forests of this ecological site have standing live timber of 500 to 8000 cubic feet per acre, with a representative value of about 1500 cubic feet per acre.
Joseph Rock described some of this area in the early 20th Century. He said, “Diospyros (lama tree) in lowland forest is especially common back of Hilo along the road to Olaa” (=Keaau). “Immediately back of Hilo is a somewhat mixed forest composed of species of trees peculiar to the dry and wet regions.”
Pathways from this state/plant community
To State 2, Mixed Native/Alien Forest, via “A&B”:
A = gradual weed invasion; B = feral pig damage.
Very aggressive weeds species are able to invade intact native forest, gradually replacing native species. This invasion is facilitated by feral pigs that damage native plants, disturb the soil, and spread weed seeds.
To State 4, Grassland, via “G&H”:
G = land clearing; H = pasture establishment.
Native Forest can be converted to Grassland by clearing the forest with heavy machinery and planting desirable pasture species. Native forest may be cleared gradually by allowing cattle access to the forest. Cattle eventually eat or destroy understory ferns, forbs, shrubs, and saplings, opening up the forest so that pasture grasses will thrive. On shallow soils over lava substrates, underlying lava rock often is ripped and crushed by heavy machinery. Ripping and crushing produces some fine mineral particles and small, abundant gaps between the rock fragments. When this is done on organic soils, about 50% of the soil organic matter may be lost in the process due to exposure to air and higher temperatures.
Plant species listed in the following tables have been observed in the course of field work or are derived from reliable records.
Origin: n = native (endemic or indigenous); a = alien (introduced by humans).
Type: t = tree; tf = tree fern; s = shrub; h = herb (forb); v = vine; f = fern; g = grasslike (grasses, sedges, rushes). Composite representation of State 1, Plant Community 1, Native Forest.