FOTG Section II. Natural Resources Information F. Ecological Site Descriptions

F162XY504HI Very Shallow Wet Ohia/Uluhe Thicket

Ecological Site Description

Ecological Site Characteristics

Site Identification

Site Type: Forestland / Site ID:F162XY504HI / MLRA: 162
Colloquial Site Name: Very Shallow Wet Ohia/Uluhe Thicket
Official Site Name: Metrosideros polymorpha/Cibotium glaucum/Dicranopteris linearis

Physiographic Features

This ecological site occurs on a broad area of young lava flows on the slope of Kilauea Volcano. Lava flows are pahoehoe (smooth, relatively unbroken).

Landform: (1) pahoehoe lava flow
Landform: (2)
Landform: (3) / Minimum / Maximum
Elevation (feet): / 50 / 1200
Slope (percent): / 2 / 10
Water Table Depth (inches): / none / 3
Flooding:
Frequency:
Duration: / very rare
-- / occasional
extremely brief
Ponding:
Depth (inches):
Frequency:
Duration: /
--
none
--nonevery briefbrieflongvery long
/
4
frequent
long
Runoff Class: / negligible / low
Aspect: (1) E
Aspect: (2) NE

Climatic Features

Average annual precipitation ranges from 120 to 150 inches. Most of the precipitation falls from October through March, with December being the wettest month. Average annual temperature is about 63 to 72 degrees F. The climate can be generally classified as udic and subtropical in nature.

Climate Chart

Minimum / Maximum
Frost Free Period (days): / 365 / 365
Freeze Free Period (days): / 365 / 365
Mean Annual Precipitation (inches): / 120 / 150
Monthly Precipitation (inches) and Temperature (0F)
Month / Jan / Feb / Mar / Apr / May / Jun / Jul / Aug / Sep / Oct / Nov / Dec
Precip. Min. / 1.0 / 2.0 / 2.0 / 2.0 / 2.0 / 0.4 / 5.0 / 1.0 / 4.0 / 4.0 / 4.0 / 1.0
Precip Max. / 44.0 / 42.0 / 46.0 / 31.0 / 32.0 / 25.0 / 23.0 / 26.0 / 21.0 / 32.0 / 32.0 / 46.0
Temp. Min / 61 / 61 / 61 / 62 / 63 / 64 / 65 / 66 / 65 / 65 / 64 / 63
Temp. Max / 77 / 76 / 76 / 77 / 78 / 79 / 80 / 80 / 81 / 80 / 78 / 77
Climate Station: (1)
Climate Station: (2) / Pahoa 65.0, 1902-1966

Influencing Water Features

Small, shallow sedge bogs can be found in disturbed areas of this ecological site. It is not known if they are natural features or caused by human disturbance.

Representative Soil Features

Typical soils formed in highly decomposed organic matter. They are well drained, and are very shallow. Available water capacity is (TBD). Permeability is rapid. Runoff is rapid. Moist colors range from black to very dark brown. Soil reactions (pH) are strongly acid (5.2-5.4) in surface horizons. Soil temperature regime is isohyperthermic. Soil moisture regimes are udic.

Predominant Parent Materials:
Kind: highly decomposed plant materials
Origin: / Surface Texture: (1) --clayclay loamcoarse sandcoarse sandy loamfine sandfine sandy loamloamloamy coarse sandloamy fine sandloamy sandloamy very fine sandsandsandy claysandy clay loamsiltsilty claysilty clay loamsilt loamsandy loamvery fine sandvery fine sandy loam
Surface Texture: (2) --clayclay loamcoarse sandcoarse sandy loamfine sandfine sandy loamloamloamy coarse sandloamy fine sandloamy sandloamy very fine sandsandsandy claysandy clay loamsiltsilty claysilty clay loamsilt loamsandy loamvery fine sandvery fine sandy loam
Subsurface Texture Group: --sandyloamyclayey
Surface Fragments <=3" (%Cover): 0
Surface Fragments >3" (%Cover): 0 / Rock Fragments <=3" (%Volume): 0
Rock Fragments >3" (%Volume): 0
Drainage Class: well / Permeability Class: rapid
Minimum / Maximum
Depth (inches): / 1 / 5
Electrical Conductivity (mmhos/cm):
Sodium Adsorption Ratio:
Calcium Carbonate Equivalent (percent):
Soil Reaction (1:1 Water):
Soil Reaction (.0-1M CaC12):
Available Water Capacity (inches):

Plant Communities

Ecological Dynamics of the Site

This plant community exists on young, very shallow soils with areas of pahoehoe outcrop. Diversity of native plant species is low. Fire and clearing of native vegetation allows alien weed species to invade and eventually dominate the landscape. Large areas of this ecological site had been converted to pasture in the past and have since been abandoned. Small, sedge-dominated wet sites occur in areas that have been cleared and have then shifted to weedy meadow vegetation. Despite the shallowness of the soils, many alien tree species are able to establish; their potential densities and sizes are not yet known, but dense stands exist, some with very tall trees. Near kipukas with older native vegetation, large (75 feet tall, 30 inch dbh) ohia trees can be found growing on these very shallow soils from seeds that established early after cooling of the lava flow. Roots of these ohia trees extend into cracks in the pahoehoe and may possibly reach into buried soils.

Ripping and crushing of the underlying pahoehoe by heavy equipment creates Arents, in which rock fragments are comminuted into smaller pieces including sand. This action causes loss of organic matter by oxidation, but creates fine, sand-filled interstices between rocks that provide protective sites for seeds. Abandoned Arents are very susceptible to weed invasion.

State and transition diagram

State 1 – Native Forest

Plant Community 1

This state represents the Historic Climax Plant Community. The general aspect of this plant community is a deep (to 12 feet) thicket of uluhe fern with a very open canopy of ohia trees that are 30 to 50 feet tall. Occasional kopiko trees and uki`uki sedges emerge through the uluhe. Pandanus is an occasional emergent nearer the coast, while tree ferns (hapu`u) may occur at the wetter, mauka extremes of the ecological site. These savannahs have standing live timber of 0 to 700 cubic feet per acre, with a representative value of about 150 cubic feet per acre.

Pathways from this state/plant community

To State 2, Plant Community 2, Weedy Meadow, via “A or B”:

A = land clearing; B = fire.

Ohia-uluhe savannah converts to Weedy Meadow through land clearing or fire. If the site is not near a heavy weed seed source, native uluhe and eventually native trees can reclaim the site without human intervention.

Plant species listed in the following tables have been observed in the course of field work or are derived from reliable records.

Abbreviations:

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, Ohia-uluhe Savannah.

State 1, Plant Community 1, Ohia-uluhe plant community.

State 2 – Weedy Meadow

This site develops in abandoned agricultural fields or home sites, or in areas that have burned. The general aspect is an open field with weedy, fire-prone grasses, clumps of weedy shrubs, vines, and small trees, and isolated medium height trees. Isolated, small wet areas dominated by a native sedge (Scleria testacea) occur. These wet areas are not apparent in the native plant community, where they are either hidden by dense uluhe ferns or do not exist at all in the conditions beneath the fern cover. Widespread, human-caused fires historically have been common in this plant community.

Pathways from this state

To State 1, Ohia-uluhe Savannah, via “D”:

D = weed control.

Uluhe fern is a very competitive, fast-growing plant that can reclaim cleared or burned sites. If the local weed seed bank is not abundant, uluhe will naturally recover a site, eventually allowing native trees to emerge through it. It has been demonstrated that moderate weed control efforts can allow uluhe to dominate a site if weeds are present (personal communication, Fred Stone, UH-Hilo, retired).

To State 3, Alien Forest, via “C”:

C = absence of fire.

Large and small alien tree species are able to grow quite well in this ecological site, and will eventually overtop and outcompete shrubs and grasses in the absence of fire.

Composite representation of State 2, Plant Community 2, Weedy Meadow.

Scientific name / %Canopy cover by height class (ft) / Total Cover / Local
common name / NRCS
common name / Origin / Type / NRCS
Code
0.1 -
2 / 2.1 -
4.5 / 4.6 -
13 / 13.1 -
40 / 40.1 -
80 / 80.1 -
120
Metrosideros polymorpha / 1 / 1 / 1 / 'ohi'a lehua / 'ohi'a lehua / n / t / MEPO5
Pandanus tectorius / tr / tr / tr / tr / tr / pandanus / Tahitian screwpine / n / t / PATE2
Psychotria sp. / tr / tr / kopiko / wild coffee / n / t / PSYCH
Ardisia elliptica / 1 / 1 / 1 / 1 / shoebutton ardisia / shoebutton / a / t / AREL4
Cecropia obtusifolia / 1 / 1 / 1 / 1 / 1 / trumpet tree / trumpet tree / a / t / CEOB
Falcataria moluccana / tr / tr / tr / tr / tr / tr / falcataria / peacocksplume / a / t / FAMO
Ficus thonningii / tr / tr / Chinese banyan / Chinese banyan / a / t / FITH2
Psidium cattleianum / 1 / 1 / 10 / 10 / waiawi / strawberry guava / a / t / PSCA
Psidium guajava / 1 / 1 / 1 / common guava / guava / a / t / PSGU
Schefflera actinophylla / 1 / 1 / 1 / 1 / 1 / octopus tree / octopus tree / a / t / SCAC2
Trema orientale / tr / tr / 1 / 1 / 1 / gunpowder tree / oriental trema / a / t / TROR
Wikstroemia sp. / tr / tr / tr / `akia / false ohelo / n / s / WIKST
Clidemia hirta / 1 / 20 / 20 / Koster's curse / soapbush / a / s / CLHI3
Lantana camara / 1 / 1 / 1 / lantana / lantana / a / s / LACA2
Melastoma candidum / 1 / 5 / 5 / 10 / melastoma / Asian melastome / a / s / MECA9
Pluchea carolinensis / 1 / 1 / 1 / sourbush / cure for all / a / s / PLCA10
Tibouchina urvilleana / 1 / 5 / 5 / 10 / glorybush / princess-flower / a / s / TIUR
Arundina graminifolia / 1 / 1 / 1 / bamboo orchid / bamboo orchid / a / h / ARGR6
Spathoglottis plicata / 1 / 1 / 1 / Philippine ground orchid / Philippine ground orchid / a / h / SPPL
Stachytarpheta sp. / 1 / 1 / porterweed / a / h / STACH2
Paederia foetida / 1 / 1 / paederia / stinkvine / a / v / PAFO3
Rubus ellipticus / 1 / 1 / 1 / yellow Himalayan raspberry / yellow Himalayan raspberry / a / v / RUEL3
Dicranopteris linearis / 30 / 30 / uluhe / Old World forkedfern / n / f / DILI
Nephrolepis multiflora / 10 / 10 / scaly swordfern / scaly swordfern / a / f / NEHI
Phymatosorus grossus / 1 / 1 / maile-scented fern / a / f / PHGR21
Machaerina sp. / 1 / 1 / `uki / twigrush / n / g / MACHA2
Scleria testacea / 5 / 5 / nutgrass / Hawai`i nutrush / n / g / SCTE6
Andropogon virginicus / 10 / 10 / broomsedge / broomsedge bluestem / a / g / ANVI2
Melinis minutiflora / 5 / 1 / molassesgrass / molassesgrass / a / g / MEMI2
Schizachyrium condensatum / 20 / 20 / beardgrass / Colombian bluestem / a / g / SCCO10
Grasslike / 5 / 30 / 30
Native Forbs
Exotic Forbs / 1 / 1 / 1
Native Vines/Epiphytes
Exotic Vines / 1 / 1 / 1
Small ferns / 30 / 30
Native Shrubs / tr / tr / tr
Exotic Shrubs / 1 / 30 / 5 / 30
Native Trees / 1 / 1 / 1
Tree ferns (native)
Exotic Trees & tree ferns / 1 / 1 / 10 / 1 / tr / 10
Lichen
Moss (on ground & logs) / 5 / 5
Moss (on trees) / 5 / 5
Logs on ground (>4" dia.)

Composite representation of State 2, Plant Community 2, Weedy Meadow.