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Ecological site VX161A01X008

Isohyperthermic Ustic Naturalized Grassland

Last updated: 4/17/2025
Accessed: 04/26/2025

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General information

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 Isohyperthermic Ustic Naturalized Grassland is of well drained, very shallow and shallow soils formed in volcanic ash deposited over pahoehoe lava; all are in the Andisols soil order. Soil temperature regimes are isohyperthermic; soil moisture regimes are ustic. Available water holding capacity is low due to coarse soil textures, very shallow to shallow depths, and/or vitric (high volcanic glass content) mineralogy. Mean annual rainfall ranges from 20 to 40 inches (508 to 1000 mm). Elevations range from 0 to 2800 feet (0 to 860 m). Common introduced trees are koa haole or white leadtree (Leucaena leucocephala). Common introduced grass species are guineagrass (Urochloa maxima) and thatching grass (Hyparrhenia rufa). Common native trees include ohia lehua (Metrosideros polymorpha) and lama (Diospyros sandwicensis); common native shrubs include pukiawe (Styphelia tameiameiae syn. Leptocophylla tameiameiae), ilima (Sida fallax), and aalii (Dodonaea viscosa).

Associated sites

VX161B01X501	Kona Weather Ustic Forest KONA WEATHER USTIC FOREST. Both ecological sites occur only on the island of Hawaii. The Kona Weather Ustic Forest occurs mostly at higher, slighly cooler, moister elevations than this ecological site. Where elevations, temperatures, and moisture amounts overlap between the two ecological sites, the Kona Weather Ustic Forest occurs on older substrates that have had more time to develop soils and vegetation communities than this ecological site. It supports short to tall stature dry forest rather than the savannas and shrublands found in this ecological site.
VX159B01X500	Udic Forest UDIC FOREST. Both ecological sites occur only on the island of Hawaii. The Udic Forest occurs almost entirely 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 shrubby savannas of this ecological site.
VX161A01X009	Isothermic Ustic Naturalized Grassland ISOTHERMIC USTIC NATURALIZED GRASSLAND. Both ecological sites occur only on the island of Hawaii. The Isothermic Ustic Naturalized Grassland occurs at higher, cooler 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 Isothermic Ustic Naturalized Grassland supports more productive, denser vegetation than this ecological site. At its higher elevations, it can support open forests with species such as koa and ohia lehua and grassland dominated by kikuyugrass and cool-season (C3) grasses rather than the guineagrass of this ecological site.

VX161B01X501

Kona Weather Ustic Forest

KONA WEATHER USTIC FOREST. Both ecological sites occur only on the island of Hawaii. The Kona Weather Ustic Forest occurs mostly at higher, slighly cooler, moister elevations than this ecological site. Where elevations, temperatures, and moisture amounts overlap between the two ecological sites, the Kona Weather Ustic Forest occurs on older substrates that have had more time to develop soils and vegetation communities than this ecological site. It supports short to tall stature dry forest rather than the savannas and shrublands found in this ecological site.

VX159B01X500

Udic Forest

UDIC FOREST. Both ecological sites occur only on the island of Hawaii. The Udic Forest occurs almost entirely 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 shrubby savannas of this ecological site.

VX161A01X009

Isothermic Ustic Naturalized Grassland

ISOTHERMIC USTIC NATURALIZED GRASSLAND. Both ecological sites occur only on the island of Hawaii. The Isothermic Ustic Naturalized Grassland occurs at higher, cooler 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 Isothermic Ustic Naturalized Grassland supports more productive, denser vegetation than this ecological site. At its higher elevations, it can support open forests with species such as koa and ohia lehua and grassland dominated by kikuyugrass and cool-season (C3) grasses rather than the guineagrass of this ecological site.

Similar sites

VX159A01X002	Rocky Alluvium Naturalized Grassland (Koa haole/guineagrass/glycine) ROCKY ALLUVIUM NATURALIZED GRASSLAND. The Rocky Alluvium Naturalized Grassland occurs only on Maui, while this ecological site occurs only on Hawaii. It has a similar climate to this ecological site. It occurs on moderately deep Mollisols that formed in the interstices of aa lava rather than the very young, very shallow to shallow Andisols that formed on the surface of pahoehoe lava that are found in this ecological site. Those deeper, higher organic matter soils give the Rocky Alluvium Naturalized Grassland greater water holding capacity. Plant species are similar between both sites, but the Rocky Alluvium Naturalized Grassland should have greater productivity than this ecological site.

VX159A01X002

Rocky Alluvium Naturalized Grassland (Koa haole/guineagrass/glycine)

ROCKY ALLUVIUM NATURALIZED GRASSLAND. The Rocky Alluvium Naturalized Grassland occurs only on Maui, while this ecological site occurs only on Hawaii. It has a similar climate to this ecological site. It occurs on moderately deep Mollisols that formed in the interstices of aa lava rather than the very young, very shallow to shallow Andisols that formed on the surface of pahoehoe lava that are found in this ecological site. Those deeper, higher organic matter soils give the Rocky Alluvium Naturalized Grassland greater water holding capacity. Plant species are similar between both sites, but the Rocky Alluvium Naturalized Grassland should have greater productivity than this ecological site.

Table 1. Dominant plant species

Tree	(1) Leucaena leucocephala
Shrub	Not specified
Herbaceous	(1) Urochloa maxima (2) Melinis repens

Legacy ID

R161AY008HI

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Physiographic features

This ecological site occurs on ash fields deposited over lava flows on sloping mountainsides of shield volcanoes. Lava flows are pahoehoe (smooth, relatively unbroken).

Table 2. Representative physiographic features

Landforms	(1) Shield volcano > Pahoehoe lava flow (2) Shield volcano > Ash field (3) Shield volcano > Mountainside
Runoff class	High to very high
Flooding frequency	None
Ponding frequency	None
Elevation	2,800 ft
Slope	2 – 20%
Water table depth	60 in
Aspect	SE, S, SW

Climatic features

Summary for this ecological site
Average annual precipitation in this ecological site ranges from 26 to 35 inches (660 to 890 mm). Most precipitation occurs from October through April. Average annual temperatures range from 70 to 72 degrees F (21 to 22 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 3. Representative climatic features

Frost-free period (characteristic range)	365 days
Freeze-free period (characteristic range)	365 days
Precipitation total (characteristic range)	26-35 in
Frost-free period (actual range)	365 days
Freeze-free period (actual range)	365 days
Precipitation total (actual range)	24-37 in
Frost-free period (average)	365 days
Freeze-free period (average)	365 days
Precipitation total (average)	30 in

Characteristic range

Actual range

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Figure 1. Monthly precipitation range

Characteristic range

Actual range

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Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

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Figure 3. Monthly maximum temperature range

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Figure 4. Monthly average minimum and maximum temperature

Figure 5. Annual precipitation pattern

Figure 6. Annual average temperature pattern

Climate stations used

(1) SEA MTN 12.15 [USC00518600], Naalehu, HI
(2) SOUTH KONA 2 2.32 [USC00518652], Captain Cook, HI

Soil features

The soils correlated with this ecological site are in the Andisols soil order that formed in recent deposits of volcanic ash. Soil temperature regimes are isohyperthermic (very warm). Soil moisture regimes are ustic (in normal years, dry for more than 90 cumulative days but less than 180 days).

Table 4. Representative soil features

Parent material	(1) Basic volcanic ash – basalt
Surface texture	(1) Ashy very fine sandy loam (2) Medial loam
Family particle size	(1) Ashy (2) Medial
Drainage class	Well drained
Permeability class	Very slow
Depth to restrictive layer	6 – 18 in
Soil depth	6 – 18 in
Surface fragment cover <=3"	5 – 10%
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	1 – 5 in
Calcium carbonate equivalent (0-40in)	Not specified
Electrical conductivity (0-40in)	2 mmhos/cm
Sodium adsorption ratio (0-40in)	Not specified
Soil reaction (1:1 water) (0-40in)	5.1 – 7.3
Subsurface fragment volume <=3" (0-40in)	30 – 60%
Subsurface fragment volume >3" (0-40in)	Not specified

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

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Standard diagram

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Ecosystem states

1. Reference State

2. Invaded Understory State

3. Invaded Over and Understory State

4. Native Forest State

5. Weed Invaded Grassland State

States 1 and 5 (additional transitions)

1. Reference State

5. Weed Invaded Grassland State

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, or fire 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. 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 by fire or by 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 ungulates access to the forest. They 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.

State 1 submodel, plant communities

1.1. Koa haole (white leadtree)/guineagrass

1.2. Thatching grass (Jaraguagrass) – guineagrass

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 1
Reference State

This state consists of two community phases dominated by introduced grass species. This is the Reference State because few intact examples of native forest remain, and the species compositions of the forests consisting of introduced species are highly 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
Koa haole (white leadtree)/guineagrass

Dominance 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. Common forage species are guineagrass (Urochloa maxima) and rose Natal grass (Melinis repens). Koa haole or white leadtree (Leucaena leucocephala) can be common and provides browse.

Dominant plant species

white leadtree (Leucaena leucocephala), tree
guineagrass (Urochloa maxima), grass

Community 1.2
Thatching grass (Jaraguagrass) – guineagrass

This 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. Koa haole or white leadtree can be present but is heavily browsed. Thatching grass or Jaraguagrass (Hyparrhenia rufa) and remnant guineagrass (Urochloa maxima) are common grass species.

Dominant plant species

jaraguagrass (Hyparrhenia rufa), tree
guineagrass (Urochloa maxima), tree

Pathway P1.1A
Community 1.1 to 1.2

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.

Pathway P1.2A
Community 1.2 to 1.1

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
Invaded Understory State

This 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
Lama - ohia lehua/lantana - aalii/ huehue haole (corkystem passionflower)/ thatching grass (jaraguagrass)

While 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), lama (Diospyros sandwicense), wiliwili (Erythrina sandwicensis), ohe makai (Polyscias sandwicensis syn. Reynoldsia sandwicensis), and naio (Myoporum sandwicense). 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. Koa haole or white leadtree (Leucaena leucocephala), christmasberry (Schinus terebinthifolius), and Java plum (Syzygium javanicum) are common, gradually forming dense stands in the understory. Asian swordfern (Nephrolepis minutiflora syn. N. brownii) forms dense stands under 2 feet (about 0.6 meter) tall. Introduced shrubs such as lantana (Lantana camara) and bush indigo (Indigofera suffruticosa) are common. Introduced grass species are abundant where light is sufficient beneath the taller plants.

Dominant plant species

lama (Diospyros sandwicensis), tree
'ohi'a lehua (Metrosideros polymorpha), tree
lantana (Lantana camara), shrub
Florida hopbush (Dodonaea viscosa), shrub
jaraguagrass (Hyparrhenia rufa), grass
corkystem passionflower (Passiflora suberosa), other herbaceous

State 3
Invaded Over and Understory State

This 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 fire or by using heavy machinery and applying aggressive weed control and ungulate-exclusion measures until desirable forages are established.

Community 3.1
Christmasberry (Brazilian pepper-tree)/lantana/huehue haole (corkystem passionflower)

Native trees persist in the overstory until they die, but they do not successfully reproduce. Introduced species present in different areas varies considerably. Possible introduced tree species include kukui or Indian walnut (Aleurites moluccana), monkeypod (Pithecellobium dulce), christmasberry (Schinus terebinthifolius), and Java plum (Syzygium javanicum. The understory varies among locations. Dense overstories of introduced trees may allow little understory to grow. Introduced Asian swordferns are typically present along with a number of introduced grass species, including guineagrass.

Dominant plant species

Brazilian peppertree (Schinus terebinthifolius), tree
lantana (Lantana camara), shrub
corkystem passionflower (Passiflora suberosa), other herbaceous

State 4
Native Forest State

This 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
Lama - ohia lehua/aalii/huehue/kawelu

The partly hypothetical community is a forest with a partly open to closed, low to medium height canopy (15 to 30 feet or 4.6 to 8.2 meters). Dominant overstory species are usually ohia lehua (Metrosideros polymorpha), lama (Diospyros sandwicensis), and wiliwili (Erythrina sandwicensis). A scattering of shrubs, small ferns, grasses, sedges, and forbs occurred in the low understory.

Dominant plant species

lama (Diospyros sandwicensis), tree
'ohi'a lehua (Metrosideros polymorpha), tree
Florida hopbush (Dodonaea viscosa), shrub
kawelu (Eragrostis variabilis), grass
queen coralbead (Cocculus orbiculatus), other herbaceous

State 5
Weed Invaded Grassland State

This 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
Christmasberry (Brazilian peppertree)/bush indigo – lantana/huehue haole (corkystem passionflower)/thatching grass (jaraguagrass)

This community phase has a wide diversity of mostly introduced species. Tree overstory is typically sparse. Christmasberry (Schinus terebinthifolius), Java plum (Syzygium javanicus) and sourbush (Pluchea carolinensis) are common and poised to expand rapidly. Asian swordfern (Nephrolepis multiflora or N. brownii in updated references) is abundant. Guineagrass is present but greatly reduced in abundance unless grazing is excluded, while species of lower forage quality such as thatching grass (Hyparrhenia rufa) and barbwire grass (Cymbopogon refractus) are abundant.

Dominant plant species

Brazilian peppertree (Schinus terebinthifolius), tree
anil de pasto (Indigofera suffruticosa), shrub
lantana (Lantana camara), shrub
jaraguagrass (Hyparrhenia rufa), grass
corkystem passionflower (Passiflora suberosa), other herbaceous

Transition T1A
State 1 to 5

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.

Restoration pathway R2B
State 2 to 1

State 2 Invaded Understory can be restored to State 1 Reference by clearing the forest understory with heavy machinery, applying aggressive weed control measures, or fire and replanting desirable forage species.

Transition T2A
State 2 to 3

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.

Restoration pathway R2A
State 2 to 4

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. Reintroduction of missing native species will be necessary.

Restoration pathway R3A
State 3 to 1

State 3 Invaded Over and Understory can be converted to State 1 Reference by clearing vegetation by fire or by using heavy machinery, appropriately dealing with slash piles, applying aggressive weed control measures, and planting desirable forage species.

Restoration pathway T4B
State 4 to 1

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 ungulates access to the forest. They eventually eat or destroy understory ferns, forbs, shrubs, and saplings, opening the forest so that introduced grasses will thrive.

Transition T4A
State 4 to 2

State 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 1

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.

Additional community tables

Supporting information

Other references

ANNOTATED REFERENCES

Abrahamson I. 2013. Fire regimes in Hawaiian plant communities. In: Fire Effects Information System, US Dept. of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Available" www.fs.fed.us/database/feis/fire_regimes/Hawaii/all.html Review of fire regimes and history for multiple generalized plant communities in the Hawaiian Islands.

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

Aa lava: A type of basaltic lava having a rough, jagged, clinkery surface and a vesicular interior.

Andisols: 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.

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.

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.

Makai: a Hawaiian word meaning “toward the sea.”

Mauka: a Hawaiian word meaning “toward the mountain” or “inland.”

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

Mathew Cocking
Amy Koch
Michael Consantinides
Kendra Moseley
Jennifer Higashino
David Clausnitzer
John Proctor
Mike Kolman
Carolyn Wong

Approval

Kendra Moseley, 4/17/2025

Acknowledgments

Assistance, advice, review, and/or insights:

Randy Bartlett, Puu Kukui Watershed Preserve
Alison Cohan, The Nature Conservancy
Michael Constantinides, NRCS-PIA
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
Jennifer Higashino, USFWS and 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	04/22/2025
Approved by	Kendra Moseley
Approval date
Composition (Indicators 10 and 12) based on	Annual Production