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Ecological site VX161A01X009
Isothermic Ustic Naturalized Grassland
Last updated: 4/17/2025
Accessed: 09/19/2026
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Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.
MLRA notes
Major Land Resource Area (MLRA): 161A–Lava Flows and Rock Outcrops
This MLRA occurs in the State of Hawaii on the Big Island of Hawaii and to a small extent on Maui. Elevation ranges from sea level to 13,796 feet (0 to 4,206 meters), which includes the tops of Mauna Kea, Mauna Loa, Haleakala, Kilauea, and Hualalai volcanoes. Slopes follow the undulating to very steep topography of the lava flows. The terrain includes barren lava flows, rocky cliffs, rock outcrops, and steep cinder cones. Lava flows are basaltic aa or pahoehoe lava. Average annual precipitation ranges from 10 to 100 inches (255 to 2,540 millimeters). Most of the rainfall occurs from October through March in most areas and from May through September in the Kona area of the Big Island. In Kona and isolated areas elsewhere, afternoon fog accumulation at higher elevations adds significant moisture by fog drip and ameliorates evapotranspiration. This effect is cut off sharply at the atmospheric inversion layer at about 6,000 feet (about 2,000 meters) elevation. Average annual air temperatures range from 38 to 76 degrees F (3 to 25 degrees C), with little seasonal variation. Freezing temperatures occur at the highest elevations. Dominant soils are Andisols and Histosols with isohyperthermic to isofrigid soil temperature regimes and ustic to udic soil moisture regimes. Large parts of the MLRA consist of miscellaneous (nonsoil) areas, including lava flows, rock outcrop, and cinder land. Native vegetation varies considerably as temperature, moisture, and soil development vary with elevation and flow age. In the driest areas near sea level, sparse, low-stature shrubs, grasses, and forbs predominate. Vegetation stature and density gradually increase with elevation to typical dry forest species such as lama, wiliwili, and alahee, koa-mamane-sandalwood or mamane-sandalwood forest, open ohia-lovegrass savanna, and finally sparse subalpine vegetation with silversword, shrubs, and grasses. Vegetation is extremely sparse at the highest elevations.
Classification relationships
This ecological site occurs within Major Land Resource Area (MLRA) 161A – Lava Flows and Rock Outcrops.
Ecological site concept
This ecological site occurs on the southeastern side of the island of Hawaii. Most of the ecological site is within Volcanoes National Park. Some is on private ranches.
The central concept of the Isothermic Ustic Naturalized Grassland is of well drained, very shallow to moderately deep soils formed in volcanic ash; most are in the Andisols soil order. Soil temperature regimes are isothermic; soil moisture regimes are ustic and, in some areas, ustic/udic intergrade or udic. Available water holding capacity is low due to ashy or sandy textures, high rock contents, shallow depths, and/or vitric (high volcanic glass content) mineralogy. Mean annual rainfall ranges from 40 to 80 inches (1000 to 2000 mm). Elevations range from 1000 to 4000 feet (310 to 1230 m).
Common introduced grass species are kikuyugrass (Cenchrus clandestinus), common velvetgrass (Holcus lanatus), rose Natal grass (Melinis repens), broomsedge bluestem (Andropogon virginicus), and thatching grass (Hyparrhenia rufa). Common native trees include koa (Acacia koa) and ohia lehua (Metrosideros polymorpha); common native shrubs include pukiawe (Styphelia tameiameiae syn. Leptocophylla tameiameiae), ulei (Osteomeles anthyllidifolia), and aalii (Dodonaea viscosa).Associated sites
VX161A01X008 Isohyperthermic Ustic Naturalized Grassland
ISOHYPERTHERMIC USTIC NATURALIZED GRASSLAND. Both ecological sites occur only on the island of Hawaii. The Isohyperthermic Ustic Naturalized Grassland occurs at lower, warmer elevations than this ecological site. Both ecological sites have shallow soils developed in young volcanic ash fields deposited over young lava flows. Soil water holding capacities are similarly low in both ecological sites. The Isohyperthermic Ustic Naturalized Grassland supports less productive, sparser vegetation than this ecological site and guineagrass rather than the kikuyugrass and cool-season (C3) grasses of this ecological site.
VX159B01X500 Udic Forest
UDIC FOREST. Both ecological sites occur only on the island of Hawaii. The Udic Forest occurs partly at higher elevations that are somewhat cooler and moister than this ecological site. Where the two ecological sites overlap in elevation, temperature, and rainfall, the deeper soils, older substrates, greater soil water holding capacity, and older, more developed vegetation communities have created tall, diverse, multi-canopy rainforest rather than the open forests of this ecological site.
VX159A01X500 Well Drained Udic and Perudic Forest
WELL DRAINED UDIC AND PERUDIC FOREST. Both ecological sites occur only on the island of Hawaii. The Deep and Very Deep Volcanic Ash Forest occurs partly at higher elevations that are somewhat cooler and much moister than this ecological site. Where the two ecological sites overlap in elevation, temperature, and rainfall, the deeper soils, older substrates, greater soil water holding capacity, and older, more developed vegetation communities have created tall, diverse, multi-canopy rainforest rather than the open forests of this ecological site.
VX162X01X503 Udic Isothermic Forest
SHALLOW WET OHIA-OLAPA FOREST. Both ecological sites occur only on the island of Hawaii. The Shallow Wet Ohia-Olapa Forest occurs at similar elevations with similar temperatures but higher rainfall than this ecological site. Landforms and soils are similarly young on both ecological sites, but the much higher weathering rates and vegetation production occurring in the wetter climate creates a dense, mostly low stature rainforest rather than the open forests of this ecological site.
Table 1. Dominant plant species
Tree (1) Metrosideros polymorpha
(2) Acacia koaShrub (1) Dodonaea viscosa
(2) Styphelia tameiameiaeHerbaceous (1) Andropogon virginicus
Legacy ID
R161AY009HI
Physiographic features
This ecological site occurs on ash fields deposited over lava flows on sloping mountainsides of shield volcanoes. Lava flows are aa (loose, cobbly) or pahoehoe (smooth, relatively unbroken).
Table 2. Representative physiographic features
Landforms (1) Shield volcano > Lava flow
(2) Shield volcano > Ash field
(3) Shield volcano > Mountainside
Runoff class Very low to very high Flooding frequency None Ponding frequency None Elevation 1000 – 4000 ft Slope 2 – 20 % Water table depth 60 in Aspect SE, S, SW Table 3. Representative physiographic features (actual ranges)
Runoff class Not specified Flooding frequency Not specified Ponding frequency Not specified Elevation 0 ft Slope 2 – 40 % Water table depth 0 in Climatic features
Summary for this ecological site
Average annual precipitation in this ecological site ranges from 40 to 80 inches (1000 to 2000 mm). Extremes of average annual precipitation range as low as 30 inches (750 mm) where this ecological site grades into a neighboring drier, lower elevation ecological site. Most of the precipitation occurs from October through April. Average annual temperatures range from 60 to 69 degrees F (16 to 20 degrees C). Rainfall occurs as trade wind showers that drift over or around Mauna Loa from the windward side of the island and as heavier rainfall during major winter storms. Major storms are important for soil moisture recharge, and the number of major storms is highly variable; drought can result from a winter with few or no storms. Due to the latitude, daylength varies little during the year, resulting in only about a 50 percent variation in solar energy input between June maximum to December minimum; this variation is somewhat less than that found in the continental United States.Table 4 Representative climatic features
Frost-free period (characteristic range) 370 days Freeze-free period (characteristic range) 370 days Precipitation total (characteristic range) 40-80 in Frost-free period (actual range) 370 days Freeze-free period (actual range) 370 days Precipitation total (actual range) 30-80 in Frost-free period (average) 370 days Freeze-free period (average) 370 days Precipitation total (average) 60 in ">Influencing water features
This ecological site has no perennial water features. Intermittent streams occur at lower elevations within this ecological site.
Soil features
Most of the soils correlated with this ecological site are in the Andisols soil order that formed in recent deposits of volcanic ash, eolian sand, and pumice. Soil temperature regimes are isothermic (warm). Soil moisture regimes are mostly ustic (in normal years, dry for more than 90 cumulative days but less than 180 days), although some soils are ustic/udic intergrades or udic ((in most years, not dry for as long as 90 cumulative days).
Table 5. Representative soil features
Parent material (1) Basic volcanic ash – basalt
(2) Eolian sands
Surface texture (1) Ashy sand
(2) Medial loam
(3) Ashy sandy loam
(4) Ashy silt loam
Family particle size (1) Ashy
(2) Fragmental
(3) Medial
(4) Sandy
Drainage class Well drained to somewhat excessively drained Permeability class Very slow to moderately rapid Depth to restrictive layer 4 – 39 in Soil depth 4 – 72 in Surface fragment cover <=3" 5 – 70 % Surface fragment cover >3" 5 – 45 % Available water capacity
(0-40in)0.6 – 4 in Calcium carbonate equivalent
(0-40in)Not specified Electrical conductivity
(0-40in)0 – 2 mmhos/cm Sodium adsorption ratio
(0-40in)Not specified Soil reaction (1:1 water)
(0-40in)3.5 – 7.8 Subsurface fragment volume <=3"
(0-40in)5 – 80 % Subsurface fragment volume >3"
(0-40in)2 – 50 % Table 6. Representative soil features (actual values)
Drainage class Well drained to excessively drained Permeability class Not specified Depth to restrictive layer 0 in Soil depth 0 in Surface fragment cover <=3" 5 – 80 % Surface fragment cover >3" 0 % Available water capacity
(0-40in)0 – 8 in Calcium carbonate equivalent
(0-40in)0 % Electrical conductivity
(0-40in)0 mmhos/cm Sodium adsorption ratio
(0-40in)0 Soil reaction (1:1 water)
(0-40in)2.9 – 7.8 Subsurface fragment volume <=3"
(0-40in)5 – 90 % Subsurface fragment volume >3"
(0-40in)0 % Ecological dynamics
The information in this ecological site description (ESD), including the state-and-transition model (STM), was developed using archaeological and historical data, professional experience, and scientific studies. The information is representative of a complex set of plant communities. Not all scenarios or plants are included. Key indicator plants, animals, and ecological processes are described to inform land management decisions.
States and community phases within this ecological site were differentiated by inspection of data; ordination programs were not available. They were verified by professional consensus and observation of examples in the field.
Natural Disturbances
The important natural disturbances in this ecological site are lava flows and volcanic ash falls. Lava flows cover existing soils and destroy all vegetation, causing soil and biological succession to restart. Lava flows also ignite nearby vegetation. The original native vegetation was able to carry fire to some extent. Deep ash falls may destroy some or all vegetation but provide a substrate that allows for relatively rapid revegetation. Shallow ash falls may leave existing vegetation fairly intact.
Human Disturbances
The most important human-related disturbances in the ecological site are clearing forests to create grazing land, foraging and trampling by feral ungulates, invasion by introduced plant and animal species, and fire. Introduced vegetation, especially grasses and some fern species, are very susceptible to catching fire and have a high capacity to carry fire.State and transition model
Custom diagramStandard diagram
Figure 1. State and Transition Model for R161AY00 (Isothermic Ustic Naturlized Grassland)
More interactive model formats are also available. View Interactive Models
More interactive model formats are also available. View Interactive Models
Click on state and transition labels to scroll to the respective textEcosystem states
States 1 and 5 (additional transitions)
T1A - State 1 Reference transitions to State 5 Weed Invaded Grassland by long-term continuous grazing and lack of weed control measures. Remnant desirable forages have been grazed out and replaced entirely by weedy grasses, forbs, shrubs, and small trees. R2B - State 2 Invaded Understory can be restored to State 1 Reference by clearing the forest understory with heavy machinery, applying aggressive weed control measures, and replanting desirable forage species. T2A - State 2 Invaded Understory transitions to State 3 Invaded Over and Understory through the process of fast-growing weeds inhibiting reproduction of native plants and gradually replacing them. This process is accelerated by feral ungulates directly damaging native plants and promoting the spread of weeds by disturbing the soil and spreading weed seeds. R2A - State 2 Invaded Understory may be restored to a facsimile of State 4 Native Forest. Construction of a suitable fence and removal of all ungulates are necessary. Intensive weed control must then be initiated and maintained in the long term. In some cases, large amounts of dead weed biomass must be dealt with by removal or decomposition. Reintroduction of missing native species will be necessary. R3A - State 3 Invaded Over and Understory can be converted to State 1 Reference by clearing vegetation using heavy machinery, appropriately dealing with slash piles, applying aggressive weed control measures, and planting desirable forage species. T4B - State 4 Native Forest can transition to State 1 Reference by clearing the forest with heavy machinery or fire 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 the forest so that introduced grasses will thrive. R5A - State 5 Weed Invaded Grassland can be restored to State 1 Reference by brush management, re-establishment of desirable forage species, persistent weed control, and prescribed grazing. T5A - State 5 Weed Invaded Grassland transitions to State 3 Invaded Over and Understory due to the presence of fast-growing, introduced tree species; fire may delay this process. State 1 submodel, plant communities
P1.1A - Phase 1.1 changes to phase 1.2 by long-term continuous grazing. Remnant high-quality forages have been reduced in abundance and largely replaced by lower-value species. Weedy forbs and shrubs are increasing. P1.2A - A grazing plan is needed that provides for intensive but temporary grazing of pastures to ensure that cattle consume some low-value forage species along with preferred forages and to allow preferred forages time to recover from defoliation. Kikuyugrass is highly competitive and able to recover with proper management. The grazing plan may require splitting the herd, creating additional water sources, and creating multiple pastures by cross-fencing. Weed control may be necessary to eliminate some species such as inedible shrubs. State 2 submodel, plant communities
State 3 submodel, plant communities
State 4 submodel, plant communities
State 5 submodel, plant communities
State 1
Reference StateThis state consists of two community phases dominated by introduced grass species. This state is the Reference State because few intact examples of native forest remain, and the species compositions of the forests consisting of introduced species are variable.
Continuous grazing results in increased abundance of less desirable forage species, as represented by the phase change from Phase 1.1 to 1.2. Longer-term overgrazing and lack of weed control measures results in a transition to State 5 Weed-Invaded Grassland.Community 1.1
Common velvetgrass – rose Natal grassDominance of desired forage species is maintained by prescribed grazing techniques that allow desired species time to recover from grazing and trampling but includes periods of grazing of sufficient intensity to suppress invasion of weedy shrubs and trees. Failure to properly maintain the selected forage species results in this community phase shifting to community phase 1.2.
There typically is little or no overstory in this community. The common forage species are kikuyugrass (Pennisetum clandestinum), common velvetgrass (Holcus lanatus), and rose Natal grass (Melinis repens).Dominant plant species
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common velvetgrass (Holcus lanatus), grass
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rose Natal grass (Melinis repens), grass
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kikuyugrass (Pennisetum clandestinum), grass
Community 1.2
Broomsedge bluestem – rose Natal grassThis community phase is dominated by grasses of lower forage value. Forage legumes largely have been grazed out, and weedy forbs and shrubs have increased. It can be shifted back to phase 1.1 by using a prescribed grazing plan.
There typically is little or no overstory in this community. Rose Natal grass (Melinis repens), broomsedge bluestem (Andropogon virginicus), and remnant kikuyugrass (Cenchrus clandestinus) are typically abundant.Dominant plant species
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broomsedge bluestem (Andropogon virginicus), other herbaceous
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rose Natal grass (Melinis repens), other herbaceous
Pathway P1.1A
Community 1.1 to 1.2Phase 1.1 changes to phase 1.2 by long-term continuous grazing. Remnant high-quality forages have been reduced in abundance and largely replaced by lower-value species. Weedy forbs and shrubs are increasing.
Pathway P1.2A
Community 1.2 to 1.1A grazing plan is needed that provides for intensive but temporary grazing of pastures to ensure that cattle consume some low-value forage species along with preferred forages and to allow preferred forages time to recover from defoliation. Kikuyugrass is highly competitive and able to recover with proper management. The grazing plan may require splitting the herd, creating additional water sources, and creating multiple pastures by cross-fencing. Weed control may be necessary to eliminate some species such as inedible shrubs.
State 2
Invaded Understory StateThis state consists of one community phase representing degraded native forest. Native trees are dominant or very common in the overstory. However, introduced trees, shrubs, vines, and ferns produce a dense layer of low, competitive vegetation that inhibits reproduction of native species. Activity of feral pigs, goats, sheep, and cattle further reduces native plant abundance and produces bare, disturbed soil patches that promote weed invasion. Eventually, this state transitions to State 3 Invaded Overstory and Understory through growth of introduced tree species.
Community 2.1
Ohia lehua – koa/sawtooth blackberry/pinkhead smartweed/annual rabbitsfoot grass – weeping grassWhile native trees are abundant in the overstory, shade-tolerant introduced trees and shrubs gradually produce extremely dense canopies and root systems that exclude other species. Dense stands of introduced ferns, vines, and grasses form a layer that inhibits reproduction of native species.
Some typical native tree species in the overstory are ohia lehua (Metrosideros polymorpha), koa (Acacia koa), lama (Diospyros sandwicense), and mamani (Sophora chrysophylla). The occurrence of species varies from site to site and along moisture and temperature gradients within the ecological site.
The understory consists almost entirely of introduced species. Strawberry guava (Psidium cattleianum), common guava (Psidium guajava), and faya or fire tree (Morella faya) are abundant, gradually forming dense stands in the understory. Asian swordfern (Nephrolepis minutiflora syn. N. brownii) form dense stands under 3 feet (about 1 meter) tall. Native uluhe fern or Old World forkedfern (Dicranopteris linearis) occurs in some locations. Kikuyugrass (Cenchrus clandestinus) can cover the ground except in the densest shade. Weeping grass (Ehrharta stipoides) thrives in shadier areas.Dominant plant species
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'ohi'a lehua (Metrosideros polymorpha), tree
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koa (Acacia koa), tree
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sawtooth blackberry (Rubus argutus), shrub
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annual rabbitsfoot grass (Polypogon monspeliensis), grass
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weeping grass (Microlaena stipoides), grass
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pinkhead smartweed (Polygonum capitatum), other herbaceous
State 3
Invaded Over and Understory StateThis state consists of one community phase dominated by introduced species in both the overstory and understory. Some individual native trees may persist for their lifetime. The diversity of weedy trees, shrubs, vines, ferns, and herbs is high, and the species mix is variable. Conversion to State 1 Reference is possible by using heavy machinery and applying aggressive weed control and ungulate-exclusion measures until desirable forages are established.
Community 3.1
Faya (fire) tree/Asian swordfern/weeping grassLarge native trees persist in the overstory until they die, but they do not successfully reproduce. Introduced species present in different areas varies considerably. Monotypic or mixed stands of strawberry guava (Psidium cattleianum), common guava (Psidium guajava), and fire tree (Morella faya) may develop.
The understory varies among locations. Dense overstories of introduced trees often allow little or no understory to grow. Introduced Asian swordferns are typically present, and grass species such as weeping grass (Ehrharta stipoides), broomsedge bluestem (Andropogon virginicus, and molassesgrass (Melinis minutiflora) grow where enough light penetrates the overstory.Dominant plant species
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firetree (Morella faya), tree
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weeping grass (Microlaena stipoides), grass
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Asian swordfern (Nephrolepis multiflora), other herbaceous
State 4
Native Forest StateThis state consists of one community phase. Because few examples of this state remain, the following description is partly hypothetical, based on observations of similar ecological sites and on the known ranges and environmental preferences of likely native plant species.
When cleared of understory and much of the overstory by machinery, fire, or long-term, heavy ungulate browsing and replanted with desirable forage species, this state transitions to State 1 Reference. Gradual invasion by weedy, introduced plant species brings a transition to State 2 Invaded Understory.Community 4.1
Ohia lehua – koa/pukiawe – uleiThe partly hypothetical community is a forest with a partly open to closed, medium to tall canopy (40 to 80 feet or 12 to 24 meters).
Dominant overstory species are usually ohia lehua (Metrosideros polymorpha), koa (Acacia koa), lama (Diospyros sandwicensis), and mamani (Sophora chrysophylla). The moister half of this ecological site probably supported a secondary open overstory of tree ferns (Cibotium spp.) A scattering of shrubs, small ferns, grasses, sedges, and forbs occurred in the low understory. Patches of uluhe fern (Dicranopteris linearis) covered the ground beneath some canopy openings.Dominant plant species
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'ohi'a lehua (Metrosideros polymorpha), tree
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koa (Acacia koa), tree
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pukiawe (Styphelia tameiameiae), shrub
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Hawai'i hawthorn (Osteomeles anthyllidifolia), shrub
State 5
Weed Invaded Grassland StateThis state consists of one community phase consisting primarily of weedy shrubs and small trees. Weedy grasses and forbs dominate between shrub patches. Introduced tree species are present and will eventually attain dominance.
Community 5.1
Common guava/Asian swordfern/pinkhead smartweed/annual rabbitsfoot grass – pitted beardgrassThis community phase has a wide diversity of mostly introduced species. Tree overstory is typically sparse.
Strawberry guava (Psidium cattleianum), common guava (Psidium guajava), christmasberry (Schinus terebinthifolius), and sourbush (Pluchea carolinensis) are common and poised to expand rapidly. Asian swordfern (Nephrolepis multiflora or N. brownii in updated references) is abundant. Forage legumes are no longer present. Kikuyugrass is still present but greatly reduced in abundance, while species of lower forage quality such as annual rabbitsfoot grass (Polypogon monspeliensis) and pitted beardgrass (Bothriochloa pertusa) are abundant.Dominant plant species
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guava (Psidium guajava), tree
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annual rabbitsfoot grass (Polypogon monspeliensis), grass
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pitted beardgrass (Bothriochloa pertusa), grass
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Asian swordfern (Nephrolepis multiflora), other herbaceous
Transition T1A
State 1 to 5State 1 Reference transitions to State 5 Weed Invaded Grassland by long-term continuous grazing and lack of weed control measures. Remnant desirable forages have been grazed out and replaced entirely by weedy grasses, forbs, shrubs, and small trees.
Restoration pathway R2B
State 2 to 1State 2 Invaded Understory can be restored to State 1 Reference by clearing the forest understory with heavy machinery, applying aggressive weed control measures, and replanting desirable forage species.
Transition T2A
State 2 to 3State 2 Invaded Understory transitions to State 3 Invaded Over and Understory through the process of fast-growing weeds inhibiting reproduction of native plants and gradually replacing them. This process is accelerated by feral ungulates directly damaging native plants and promoting the spread of weeds by disturbing the soil and spreading weed seeds.
Restoration pathway R2A
State 2 to 4State 2 Invaded Understory may be restored to a facsimile of State 4 Native Forest. Construction of a suitable fence and removal of all ungulates are necessary. Intensive weed control must then be initiated and maintained in the long term. In some cases, large amounts of dead weed biomass must be dealt with by removal or decomposition. Reintroduction of missing native species will be necessary.
Restoration pathway R3A
State 3 to 1State 3 Invaded Over and Understory can be converted to State 1 Reference by clearing vegetation using heavy machinery, appropriately dealing with slash piles, applying aggressive weed control measures, and planting desirable forage species.
Transition T4B
State 4 to 1State 4 Native Forest can transition to State 1 Reference by clearing the forest with heavy machinery or fire 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 the forest so that introduced grasses will thrive.
Transition T4A
State 4 to 2State 4 Native Forest transitions to State 2 Invaded Understory by aggressive introduced species invading intact native forest and gradually replacing native species in the understory. This invasion is facilitated by feral ungulates that damage and consume native plants, disturb the soil, and spread weed seeds.
Restoration pathway R5A
State 5 to 1State 5 Weed Invaded Grassland can be restored to State 1 Reference by brush management, re-establishment of desirable forage species, persistent weed control, and prescribed grazing.
Transition T5A
State 5 to 3State 5 Weed Invaded Grassland transitions to State 3 Invaded Over and Understory due to the presence of fast-growing, introduced tree species; fire may delay this process.
Additional community tables
Table 7. Community 1.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 8. Community 1.2 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 9. Community 2.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 10. Community 3.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 11. Community 4.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Table 12. Community 5.1 plant community composition
Group Common name Symbol Scientific name Annual production () Foliar cover (%) Interpretations
Supporting information
Other references
ANNOTATED REFERENCES
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Armstrong RW. 1973. Atlas of Hawaii. University of Hawai`i Press, Honolulu. General reference for climate, land use, land forms, etc.
Athens JS. Ch. 12 Hawaiian Native Lowland Vegetation, IN Prehistory in Historical Ecology in the Pacific Islands – Prehistoric Environmental and Landscape Change. Kirch, PV and TL Hunt, eds. 1997. Yale U. Press, New Haven. General discussion of effects of prehistoric Polynesians on native lowland vegetation.
Burney DA, HF James, LP Burney, SL Olson, W Kikuchi, WL Wagner, M Burney, D McCloskey, D Kikuchi, FV Grady, R Gage II, and R Nishek. 2001. Fossil evidence diverse biota from Kauai and its transformation since human arrival. Ecological Monographs 71:615-641. Investigation of fossil evidence to trace changes in Hawaiian biota over time; generally applicable to all Hawaiian islands.
Craighill ES and EG Handy. 1991. Native Planters in Old Hawaii – Their Life, Lore, and Environment. Bernice P. Bishop Museum Bulletin 233, Bishop Museum Press, Honolulu, HI Discussion of early agriculture in Hawaii.
Cuddihy LW and CP Stone. 1990. Alteration of Native Hawaiian Vegetation: Effects of Humans, Their Activities and Introductions. Honolulu: University of Hawaii Cooperative National Park Resources Study Unit. General account of human effects on native Hawaiian vegetation.
Deenik J and AT McClellan. 2007. Soils of Hawaii. Soil and Crop Management, Sept. 2007, SCM-20. Cooperativve Extension Service, College of Tropical Agriculture and Human Resources. University of Hawaii at Manoa. Available online at: https://www.ctahr.hawaii.edu/oc/freepubs/pdf/SCM-20.pdf Discussion of soil orders and their practical implications in Hawaii.
Dixon JB and Schulze DG, eds. 2002. Soil Mineralogy with Environmental Applications. Volume 7. Soil Science Society of America. Available online at: https://acsess.onlinelibrary.wiley.com/doi/book/10.2136/sssabookser7 Exhaustive treatment of basics of soil mineralogy and implications for environmental management.
Giambelluca TW and TA Schroeder. 1998. Climate. In Atlas of Hawaii, 3rd edition. SP Juvik, JO Juvik, and RR Paradise, eds. pp. 49-59. Honolulu: University of Hawaii Press. Standard geographical reference work for Hawaii.
Hazlett RW and DW Hyndman. 1996. Roadside Geology of Hawaii. Mountain Press Publishing Company, Missoula MT. General account of geologic history of Hawaii.
Henke LA. 1929. A Survey of Livestock in Hawaii. Research Publication No. 5. University of Hawaii, Honolulu. Early assessment and history of effects of European livestock on Hawaiian ecosystems.
Imada, C. 2012. Hawaiian Native and Naturalized Vascular Plants Checklist (December 2012 update). Bishop Museum Technical Report 60. Bishop Museum Press, Honolulu. Constantly-updated list of vascular plants of Hawaii, including latest nomenclature and species occurrences on each island.
Kirch PV. 1982. The impact of the prehistoric Polynesians in the Hawaiian ecosystem. Pacific Science 36(1):1-14. General discussion of effects of prehistoric Polynesians on native vegetation.
Kirch PV. 1985. Feathered Gods and Fishhooks: An Introduction to Hawaiian Archaeology and Prehistory. Honolulu: University of Hawaii Press. General discussion of effects of prehistoric Polynesians on native vegetation.
Kirch PV. 2000. On the Road of the Winds: An Archaeological History of the Pacific Islands Before European Contact. Berkeley: University of California Press. General discussion of effects of prehistoric Polynesians on native vegetation.
Little EL Jr. and RG Skolmen. 1989. Common Forest Trees of Hawaii (Native and Introduced). US Department of Agriculture-US Forest Service Agriculture Handbook No. 679. (out of print). Available at www.fs.fed.us/psw/publications/documents/misc/ah679.pdf Information on common native and introduced tree species in Hawaii. Especially useful for introduced species.
Mueller-Dombois D and FR Fosberg. 1974. Vegetation Map of Hawaii Volcanoes National Park. Technical Report No. 4. Cooperative National Park Resources Studies Unit. Map of HVNP vegetation at 1:52,000 scale with discussions of the vegetation types.
Mueller-Dombois D and FR Fosberg. 1998. Vegetation of the Tropical Pacific Islands. Springer-Verlag New York, Inc. General account of tropical Pacific Island vegetation, with section on Hawaii. Discussion of likely effect of stoniness on soil moistue storage in dry habitats.
Palmer DD. 2003. Hawaii’s Ferns and Fern Allies. University of Hawaii Press, Honolulu. Standard reference for Hawaiian ferns and fern allies.
Pratt HD. 1998. A Pocket Guide to Hawaii’s Trees and Shrubs. Mutual Publishing, Honolulu. Useful guide to common tree and plant species, with color photos.
Reppun F, Silva JHS, Wong K, and Deenik JL. 2017. A Soil Phosphorus Primer for Hawaiian Soils. Soil and Crop Management, August 2017, SCM-33. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. Available online at: https://www.ctahr.hawaii.edu/oc/freepubs/pdf/SCM-33.pdf Practical discussion of soil phosphorus for Hawaii.
Ripperton JC and EY Hosaka. 1942. Vegetation zones of Hawaii. Hawaii Agricultural Experiment Station Bulletin 89:1-60. Broad-scale map of vegetation zones in Hawaii.
Rock JF. The Indigenous Trees of the Hawaiian Islands. 1st edition 1913, reprinted 1974, Charles E. Tuttle Company, Rutland, VT and Tokyo, Japan. Very useful account observations of native vegetation in Hawaii from early 20th century. Can be paired with GIS layer of place names to locate species observations.
Shoji SD, M Nanzyo, and R Dahlgren. 1993. Volcanic Ash Soils: Genesis, Properties and Utilization. Elsevier, New York. Detailed discussion of volcanic ash soils. Not specific to Hawaii, but very informative.
Silva JA and R Uchida, eds. 2000. Plant Nutrient Management in Hawaii’s Soils, Approaches for Tropical and Subtropical Agriculture. College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa. Available online at: https://www.ctahr.hawaii.edu/oc/freepubs/pdf/pnm0.pdf Practical discussion of plant nutrient management for Hawaii.
Sohmer SH and R Gustafson. 2000. Plants and Flowers of Hawaii. University of Hawaii Press, Honolulu. A good general discussion, with color photographs, primarily of native Hawaiian plants and vegetation types.
Soil Survey Staff. 2014. Soil Taxonomy, Twelfth Edition. USDA – NRCS. Standard book of soil taxonomy; useful for terminology and interpretation of soils, also.
Steadman DW. 1995. Prehistoric extinctions of Pacific island birds: biodiversity meets zooarchaeology. Science 267:1123-1131. Discussion of loss of many bird species, including flightless birds.
USDA-NRCS-PIA Threatened & Endangered Species GIS files. Not publicly available. Specific locations of observations of many native Hawaiian plant species.
USDA-NRCS. 2011. Soil Survey Laboratory Information Manual. Soil Survey Investigations Report No. 45, Version 2.0. National Soil Survey Center, Lincoln, Nebraska.
USDA-NRCS. 2006. Major Land Resource Regions. USDA Agriculture Handbook 296. http://soils.usda.gov/MLRAExplorer Description of MLRAs of Hawaii.
USDA-NRCS. Island of Hawaii Soil Surveys 801 and 701. Available online at https://websoilsurvey.sc.egov.usda.gov/App/HomePage.htm The latest NRCS soil survey for the island of Hawaii.
USDA-SCS. 1972. Soil Survey of Islands of Kauai, Oahu, Maui, Molokai, and Lanai, State of Hawaii. Foote DE, Hill EL, Nakamura S, and F Stephens, in cooperation with The University of Hawaii Agricultural Experiment Station. The latest NRCS soil survey for these islands. Some of the taxonomic names are outdated.
USDI-USGS. 2006. A GAP Analysis of Hawaii. Final Report and Data. GIS map of vegetation types and land use in Hawaii based on remote sensing. Very general, occasionally inaccurate, but useful.
Vitousek P. 2004. Nutrient Cycling and Limitation: Hawai`i as a Model Ecosystem. Princeton University Press, Princeton and Oxford. Discussion of development of soils, soil nutrients, and plant species in Hawaiian Archipelago.
Wagner WL, DR Herbst, and SH Sohmer. 1999. Manual of the Flowering Plants of Hawaii, Revised Edition. Bishop Museum Press, Honolulu. Standard reference of flowering plants of Hawaii.
Western Regional Climate Center, cited 2020. Climate of Hawaii. Available: https://wrcc.dri.edu/Climate/narrative_hi.php Detailed summary of climate of Hawaiian Islands.
Whistler, WA. 1995. Wayside Plants of the Islands: A Guide to the Lowland Flora of the Pacific Islands. Isle Botanica, Honolulu. Reference of common introduced plant species in lowland areas of the Pacific Islands including Hawaii; with color photographs.
DEFINITIONS
These definitions have been greatly simplified for brevity and do not cover every aspect of each topic.
Aa lava: A type of basaltic lava having a rough, jagged, clinkery surface and a vesicular interior.
Andisols: Andisols are soils formed in volcanic ash and defined as soils containing high proportions of glass and amorphous colloidal materials, including allophane, imogolite and ferrihydrite.
Ash field: a land area covered by a thick or distinctive deposit of volcanic ash that can be traced to a specific source and has well defined boundaries. The term “ash flow” is erroneously used in the Physiographic section of this ESD due to a flaw in the national database.
Ashy: A “soil texture modifier” for volcanic ash soils having a water content at the crop wilting point of less than 30 percent; a soil that holds relatively less water than “medial” and “hydrous” soils.
Available water capacity: The amount of soil water available to plants to the depth of the first root-restricting layer.
CaCO3 equivalent: The amount of free lime in a soil. Free lime exists as solid material and typically occurs in regions with a dry climate.
Canopy cover: The percentage of ground covered by the vertical projection downward of the outermost perimeter of the spread of plant foliage. Small openings within the canopy are included.
Community pathway: A description of the causes of shifts between community phases. A community pathway is reversible and is attributable to succession, natural disturbances, short-term climatic variation, and facilitating practices, such as grazing management.
Community phase: A unique assemblage of plants and associated dynamic soil properties within a state.
Dominant species: Plant species or species groups that exert considerable influence upon a community due to size, abundance, or cover.
Drainage class: The frequency, duration, and depth of a water table in a soil. There are seven drainage classes, ranging from “excessively drained” (soils with very rare or very deep water tables) to “well drained” (soils that provide ample water for plant growth but are not so wet as to inhibit root growth) to “very poorly drained” (soils with a water table at or near the surface during much of the growing season that inhibits growth of most plants).
Electrical conductivity (EC): A measure of the salinity of a soil. The standard unit is deciSiemens per meter (dS/m), which is numerically equivalent to millimhos per centimeter (mmhos/cm). An EC greater than about 4 dS/m indicates a salinity level that is unfavorable to growth of most plants.
Ion exchange capacity: The ability of soil materials such as clay or organic matter to retain ions (which may be plant nutrients) and to release those ions for uptake by roots.
Isofrigid soil temperature regime: A regime which has mean annual soil temperatures of greater than 32 degrees F (0 °C), but less than 46.4 (8 °C), with a difference between mean summer and mean winter soil temperatures of less than 41 degrees F (5 °C) at a specified depth.
Isohyperthermic soil temperature regime: A regime in which mean annual soil temperature is 72 degrees F (22 degrees C) or higher and mean summer and mean winter soil temperatures differ by less than 11 degrees F (6 degrees C) at a specified depth.
Isomesic soil temperature regime: A regime in which mean annual soil temperature is 47 degrees F (8 degrees C) or higher but lower than 59 degrees F (15 degrees C) and mean summer and mean winter soil temperatures differ by less than 11 degrees F (6 degrees C) at a specified depth.
Isothermic soil temperature regime: A regime in which mean annual soil temperature is 59 degrees F (15 degrees C) or higher but lower than 72 degrees F (22 degrees C) and mean summer and mean winter soil temperatures differ by less than 11 degrees F (6 degrees C) at a specified depth.
Major Land Resource Area (MLRA): A geographic area defined by NRCS that is characterized by a particular pattern of soils, climate, water resources, and land uses. The island of Hawaii contains nine MLRAs, some of which also occur on other islands in the state.
Naturalized plant community: A community dominated by adapted, introduced species. It is a relatively stable community resulting from secondary succession after disturbance. Most grasslands in Hawaii are in this category.
Pahoehoe lava: A type of basaltic lava with a smooth, billowy, or rope-like surface and vesicular interior.
Parent material: Unconsolidated and chemically weathered material from which a soil is developed.
pH: The numerical expression of the relative acidity or alkalinity of a soil sample. A pH of 7 is neutral; a pH below 7 is acidic and a pH above 7 is basic.
Reference community phase: The phase exhibiting the characteristics of the reference state and containing the full complement of plant species that historically occupied the site. It is the community phase used to classify an ecological site.
Reference state: A state that describes the ecological potential and natural or historical range of variability of an ecological site.
Restoration pathway: A term describing the environmental conditions and practices that are required to recover a state that has undergone a transition.
Sodium adsorption ratio (SAR): A measure of the amount of dissolved sodium relative to calcium and magnesium in the soil water. SAR values higher than 13 create soil conditions unfavorable to most plants.
Soil moisture regime: A term referring to the presence or absence either of ground water or of water held at a tension of less than 1500 kPa (the crop wilting point) in the soil or in specific horizons during periods of the year.
Soil temperature regime: A defined class based on mean annual soil temperature and on differences between summer and winter temperatures at a specified depth.
Soil reaction: Numerical expression in pH units of the relative acidity or alkalinity or a soil.
State: One or more community phases and their soil properties that interact with the abiotic and biotic environment to produce persistent functional and structural attributes associated with a characteristic range of variability.
State-and-transition model: A method used to display information about relationships between vegetation, soil, animals, hydrology, disturbances, and management actions on an ecological site.
Transition: A term describing the biotic or abiotic variables or events that contribute to loss of state resilience and result in shifts between states.
Udic soil moisture regime: A regime in which the soil is not dry in any part for as long as 90 cumulative days in normal years, and so provides ample moisture for plants. In Hawaii it is associated with forests in which hapuu (tree ferns) are usually moderately to highly abundant.
Ustic soil moisture regime: A regime in which moisture is limited but present at a time when conditions are suitable for plant growth. In Hawaii it usually is associated with dry forests and subalpine shrublands.Contributors
David Clausnitzer
John Proctor
Mike Kolman
Carolyn Wong
Amy Koch
Mathew Cocking
Kendra Moseley
Michael Constantinides
Jennifer HigashinoApproval
Kendra Moseley, 4/17/2025
Acknowledgments
Assistance, advice, review, and/or insights: Randy Bartlett, Puu Kukui Watershed Preserve Alison Cohan, The Nature Conservancy Gordon Cran, Kapapala Ranch Diana Crow, Ulupalakua Ranch Lance DeSilva, Hawaii DLNR Kerri Fay, Waikamoi Preserve, The Nature Conservancy Alex Franco, Kaupo Ranch Ranae Ganske-Cerizo, NRCS Carl Hashimoto, NRCS Bob Hobdy, consultant, Maui Wallace Jennings, NRCS Mel Johansen, The Nature Conservancy Jordan Jokiel, Haleakala Ranch David Leonard, volunteer Penny Levin Reese Libby, GIS - NRCS Hannah Lutgen, Maui SWCD Joseph May, NRCS Scott Meidel, Haleakala Ranch Anna Palomino, Hoolawa Farms Inc. Jon Price, USGS Tamara Sherrill, USFWS, Maui Nui Botanical Garden Amber Starr, Hana Ranch Kahana Stone, NRCS Mark Vaught, Water Resources, Alexander & Baldwin Jacqueline Vega, NRCS Rich von Wellsheim, Whispering Bamboos, Kipahulu
Rangeland health reference sheet
Interpreting Indicators of Rangeland Health is a qualitative assessment protocol used to determine ecosystem condition based on benchmark characteristics described in the Reference Sheet. A suite of 17 (or more) indicators are typically considered in an assessment. The ecological site(s) representative of an assessment location must be known prior to applying the protocol and must be verified based on soils and climate. Current plant community cannot be used to identify the ecological site.
Author(s)/participant(s) Contact for lead author Date 09/19/2026 Approved by Approval date Composition (Indicators 10 and 12) based on Annual Production Indicators
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Number and extent of rills:
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Presence of water flow patterns:
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Number and height of erosional pedestals or terracettes:
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Bare ground from Ecological Site Description or other studies (rock, litter, lichen, moss, plant canopy are not bare ground):
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Number of gullies and erosion associated with gullies:
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Extent of wind scoured, blowouts and/or depositional areas:
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Amount of litter movement (describe size and distance expected to travel):
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Soil surface (top few mm) resistance to erosion (stability values are averages - most sites will show a range of values):
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Soil surface structure and SOM content (include type of structure and A-horizon color and thickness):
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Effect of community phase composition (relative proportion of different functional groups) and spatial distribution on infiltration and runoff:
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Presence and thickness of compaction layer (usually none; describe soil profile features which may be mistaken for compaction on this site):
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Functional/Structural Groups (list in order of descending dominance by above-ground annual-production or live foliar cover using symbols: >>, >, = to indicate much greater than, greater than, and equal to):
Dominant:
Sub-dominant:
Other:
Additional:
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Amount of plant mortality and decadence (include which functional groups are expected to show mortality or decadence):
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Average percent litter cover (%) and depth ( in):
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Expected annual annual-production (this is TOTAL above-ground annual-production, not just forage annual-production):
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Potential invasive (including noxious) species (native and non-native). List species which BOTH characterize degraded states and have the potential to become a dominant or co-dominant species on the ecological site if their future establishment and growth is not actively controlled by management interventions. Species that become dominant for only one to several years (e.g., short-term response to drought or wildfire) are not invasive plants. Note that unlike other indicators, we are describing what is NOT expected in the reference state for the ecological site:
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Perennial plant reproductive capability:
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PrintThe Ecosystem Dynamics Interpretive Tool is an information system framework developed by the USDA-ARS Jornada Experimental Range, USDA Natural Resources Conservation Service, and New Mexico State University.
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