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Ecological site VX161A01X001

Isohyperthermic Desert

Last updated: 4/17/2025
Accessed: 04/24/2025

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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 leeward coast of the island of Hawaii from the southwestern slopes of Hualalai near Kailua-Kona and northward to the Puako area. Most of the area is owned by the State of Hawaii, private ranches, and other private holdings that include large seaside resorts. It is easily accessible along Highway 19.

The central concept of the Isohyperthermic Desert is of well to somewhat excessively drained, shallow (over pahoehoe) to moderately deep (with high rock content) Aridisols, Entisols, and one Folist formed in volcanic ash or decomposed organic material mixed with volcanic ash. Stoniness or shallowness reduce the plant available water holding capacity of the soils. That characteristic combined with low annual rainfall (7 to 20 inches or 175 to 500 millimeters) and exceptionally warm soil temperatures (76 to 87F or 24 to 31C) result in low vegetation production. The soil temperature regime is isohyperthermic; soil moisture conditions (aridic/torric regime) are dry most of the year. Elevations range from sea level (0 to 1500 feet or 0 to 460 meters). Because very little of the original native vegetation remains, the reference state of this ecological site consists of the dominant naturalized grassland vegetation. The dominant grass species is crimson fountaingrass (Pennisetum setaceum). The dominant naturalized tree is kiawe (Prosopis pallida). The original native vegetation was dry savanna or shrubland. Some common native species, based on the current environment and remnant occurrences, are alahee (Psydrax odorata), ohe makai (Polyscias sandwicensis syn. Reynoldsia sandwicensis), wiliwili (Erythrina sandwicensis), naio (Myoporum sandwicense), aalii (Dodonaea viscosa), ilima (Sida fallax), and native grasses.

Associated sites

VX161B01X501	Kona Weather Ustic Forest The Kona Weather Ustic Forest adjoins this ecological site where they meet on the west coast of Hawaii. It occurs in a cooler, moister, and cloudier climate on soils that generally have higher water-holding capacity and organic matter content than the Aridic Desert.
VX161B01X500	Ustic Isothermic Forest The Ustic Isothermic Forest adjoins this ecological site where they meet at the higher elevations of this ecological site. It occurs in a cooler, moister, and cloudier climate on soils that have higher water-holding capacity and organic matter content than the Aridic Desert. The Ustic Isothermic Forest supports open to closed canopy, medium stature native forest rather than native shrubland, and the main introduced forage species is kikuyugrass rather than fountaingrass or buffelgrass.
VX157X01X003	Rocky Volcanic Ash Savanna The Rocky Volcanic Ash Savanna occurs on deeper soils with higher water holding capacity and organic matter content than this ecological site. It supports denser, taller stands of kiawe than this ecological site probably supported denser native vegetation with more trees than this ecological site. The main forage species is buffelgrass rather than fountaingrass with some buffelgrass as found in this ecological site. However, fountaingrass may invade this ecological site in time.

VX161B01X501

Kona Weather Ustic Forest

The Kona Weather Ustic Forest adjoins this ecological site where they meet on the west coast of Hawaii. It occurs in a cooler, moister, and cloudier climate on soils that generally have higher water-holding capacity and organic matter content than the Aridic Desert.

VX161B01X500

Ustic Isothermic Forest

The Ustic Isothermic Forest adjoins this ecological site where they meet at the higher elevations of this ecological site. It occurs in a cooler, moister, and cloudier climate on soils that have higher water-holding capacity and organic matter content than the Aridic Desert. The Ustic Isothermic Forest supports open to closed canopy, medium stature native forest rather than native shrubland, and the main introduced forage species is kikuyugrass rather than fountaingrass or buffelgrass.

VX157X01X003

Rocky Volcanic Ash Savanna

The Rocky Volcanic Ash Savanna occurs on deeper soils with higher water holding capacity and organic matter content than this ecological site. It supports denser, taller stands of kiawe than this ecological site probably supported denser native vegetation with more trees than this ecological site. The main forage species is buffelgrass rather than fountaingrass with some buffelgrass as found in this ecological site. However, fountaingrass may invade this ecological site in time.

Similar sites

VX157X01X001	Torric Naturalized Grassland The Torric Naturalized Grassland is at South Point on the island of Hawaii. Similarly to this ecological site, it has a very warm, dry climate and soils with low water holding capacity. However, it has higher rainfall and lower soil temperatures than this ecological site.
VX158X01X002	Isohyperthermic Torric Naturalized Grassland Kiawe/buffelgrass (Prosopis pallida/Pennisetum ciliare) The Isohyperthermic Torric Naturalized Grassland occurs on all the major islands except Hawaii. It has a similarly very warm, dry climate to this ecological site but with higher rainfall and lower soil temperatures. It also has deeper soils with greater water holding capacity, and the soils are mostly Mollisols and Oxisols rather than the Aridisols, Entisols, and Histosols of this ecological site. Buffelgrass and, in moister areas, guineagrass are the main forage species in the Isohyperthermic Torric Naturalized Grassland, rather than crimson fountaingrass. As of now, there is little indication of fountaingrass invasion being allowed to gain a foothold on the islands on which that ecological site occurs.
VX158X01X004	Rocky Isohyperthermic Torric Naturalized Grassland Kiawe/uhaloa/buffelgrass (Prosopis pallida/Waltheria indica/Pennisetum ciliare) The Rocky Isohyperthermic Torric Naturalized Grassland occurs on all the major islands except Hawaii. It has a similarly very warm, dry climate to this ecological site with similar rainfal but lower soil temperatures. It also has soils with low water holding capacity. The soils are mostly Mollisols and Oxisols rather than the Aridisols, Entisols, and Histosols of this ecological site. Buffelgrass is the main forage species in the Rocky Isohyperthermic Torric Naturalized Grassland, rather than crimson fountaingrass. As of now, there is little indication of fountaingrass invasion being allowed to gain a foothold on the islands on which that ecological site occurs.

VX157X01X001

Torric Naturalized Grassland

The Torric Naturalized Grassland is at South Point on the island of Hawaii. Similarly to this ecological site, it has a very warm, dry climate and soils with low water holding capacity. However, it has higher rainfall and lower soil temperatures than this ecological site.

VX158X01X002

Isohyperthermic Torric Naturalized Grassland Kiawe/buffelgrass (Prosopis pallida/Pennisetum ciliare)

The Isohyperthermic Torric Naturalized Grassland occurs on all the major islands except Hawaii. It has a similarly very warm, dry climate to this ecological site but with higher rainfall and lower soil temperatures. It also has deeper soils with greater water holding capacity, and the soils are mostly Mollisols and Oxisols rather than the Aridisols, Entisols, and Histosols of this ecological site. Buffelgrass and, in moister areas, guineagrass are the main forage species in the Isohyperthermic Torric Naturalized Grassland, rather than crimson fountaingrass. As of now, there is little indication of fountaingrass invasion being allowed to gain a foothold on the islands on which that ecological site occurs.

VX158X01X004

Rocky Isohyperthermic Torric Naturalized Grassland Kiawe/uhaloa/buffelgrass (Prosopis pallida/Waltheria indica/Pennisetum ciliare)

The Rocky Isohyperthermic Torric Naturalized Grassland occurs on all the major islands except Hawaii. It has a similarly very warm, dry climate to this ecological site with similar rainfal but lower soil temperatures. It also has soils with low water holding capacity. The soils are mostly Mollisols and Oxisols rather than the Aridisols, Entisols, and Histosols of this ecological site. Buffelgrass is the main forage species in the Rocky Isohyperthermic Torric Naturalized Grassland, rather than crimson fountaingrass. As of now, there is little indication of fountaingrass invasion being allowed to gain a foothold on the islands on which that ecological site occurs.

Table 1. Dominant plant species

Tree	(1) Prosopis pallida
Shrub	Not specified
Herbaceous	(1) Pennisetum setaceum (2) Pennisetum ciliare

Legacy ID

R161AY001HI

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Physiographic features

This ecological site occurs on shield volcanoes with basic igneous rock deposited as nearly level to gently sloping lava flows and ash fields.

Table 2. Representative physiographic features

Landforms	(1) Shield volcano > Lava flow (2) Shield volcano > Ash field
Runoff class	Very low to high
Flooding frequency	None
Ponding frequency	None
Elevation	0 – 457 m
Slope	2 – 20%
Ponding depth	0 cm
Water table depth	152 cm
Aspect	W, NW, SW

Climatic features

Summary for this ecological site
Average annual precipitation in this ecological site ranges from 13 to 17 inches (330 to 430 millimeters). Extremes of annual precipitation may range from 12 to 18 inches (305 to 455 millimeters). Most of the precipitation occurs from October through April. Average annual air temperatures range from 76 to 87F (24 to 31C). Conditions typically are dry. Rainfall occurs as light trade wind showers that drift over or around the mountains from the windward side of the islands 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. Conditions are generally clear to lightly cloudy.

General principles
Air temperature in the Hawaiian Islands is buffered by the surrounding ocean so that the range in temperature through the year is narrow. This creates “iso-“ soil temperature regimes in which mean summer and winter temperatures differ by less than 6 degrees C (11 degrees F).

Two seasons can be defined during the year: a winter season from October through April and a summer season from May through September. Summer has warmer temperatures, steadier and stronger trade winds, few widespread rainstorms, and generally lower average monthly rainfall than winter. The Kona Coast of Hawaii (the “Big Island”) is the only area where summer rainfall exceeds winter rainfall. Differences in rainfall amounts between winter and summer are most marked in low elevation dry areas; wetter areas exhibit less seasonal variation in rainfall.

The islands lie within the trade wind zone. Moisture is picked up from the ocean by trade winds to an altitude of about 6,000 feet (1850 meters). As the trade winds from the northeast are forced up the islands’ mountains their moisture condenses, creating rain on the windward slopes; the leeward sides of the island receive little of this moisture. The zones of highest rainfall on the windward flanks of the highest mountains (more than 10,000 feet or 3075 meters), which include Mauna Kea, Mauna Loa, and Haleakala, occur at elevations of 2,000 to 4,000 feet (615 to 1230 meters). A temperature inversion that fluctuates between about 5,000 and 7,000 feet (1540 to 2150 meters) on these three highest mountains creates a boundary between lower moist air and higher dry air. Above the inversion, rainfall is scant, skies are usually clear, humidity is low, and temperatures can drop below freezing. On West Maui, Kauai, Molokai, Oahu, and Lanai, where the mountains are all lower than 6,000 feet (1850 meters), the highest rainfall amounts occur along or near the summits. The moist trade winds usually flow across these lower mountains and around the higher mountains. Lanai is sheltered from the trade winds by the much larger island of Maui, putting it in a rain shadow during trade wind weather; rainfall on Lanai is uncharacteristically low for Hawaii.

Besides the trade winds discussed above, other rainfall sources on the Hawaiian Islands include: a) Widespread winter storms that usually approach the islands from the west, producing heavy rainstorms that primarily affect the leeward sides but can envelope much larger areas; b) "Naulu storms" (Leopold 1948) caused by local convergence of sea breezes and trade winds to produce summertime cumulus clouds, resulting in infrequent, short-duration, high-intensity rainfall and afternoon shade over leeward dry areas; and c) Fog drip, particularly important to areas with relatively low rainfall, that adds a significant amount of water to areas where clouds intersect mountains (Juvik and Nullet 1993; Western Regional Climate Center).

The heaviest rains are brought by winter storms. The greatest amounts of storm rainfall do not always occur in areas with the highest average rainfall, and a storm may bring half of the mean annual rainfall to a dry area in one day.

Table 3. Representative climatic features

Frost-free period (characteristic range)	365 days
Freeze-free period (characteristic range)	365 days
Precipitation total (characteristic range)	330-432 mm
Frost-free period (actual range)	365 days
Freeze-free period (actual range)	365 days
Precipitation total (actual range)	305-457 mm
Frost-free period (average)	365 days
Freeze-free period (average)	365 days
Precipitation total (average)	381 mm

Characteristic range

Actual range

Bar

Line

Figure 1. Monthly precipitation range

Characteristic range

Actual range

Bar

Line

Figure 2. Monthly minimum temperature range

Characteristic range

Actual range

Bar

Line

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) KE-AHOLE PT 68.13 [USC00513911], Kailua Kona, HI
(2) KAILUA KONA KE-AHOLE AP [USW00021510], Kailua Kona, HI

Soil features

The soils in this ecological site are mostly Aridisols and Entisols that have formed in volcanic ash deposited over lava flows. One soil is in the Histosols order, having formed in organic matter mixed with volcanic ash. The unifying factors are high soil temperatures and dryness.

Soil temperature regimes are isohypothermic (very warm) with mean temperatures of 76 to 87F (24 to 31C). Soil moisture regimes are aridic or torric (in normal years, dry for more than half of the growing season and moist for less than 90 consecutive days during the growing season). All the soils are well drained to somewhat excessively drained.

Surface horizons have pH ranging from 6.2 to 7.6. Extreme pH in subsurface horizons within 30 inches (75 centimeters) of the surface range from 6.8 to 7.6. All the mineral soils are in the isotic mineralogy class, meaning the fine particles consist of poorly-crystallized minerals such as allophane, have mostly pH-dependent charge (giving them some cation retention capacity within this pH range), and have a high capacity to fix phosphorus in forms that are poorly available to plants.

Table 4. Representative soil features

Parent material	(1) Basic volcanic ash – basalt (2) Organic material
Surface texture	(1) Extremely cobbly, extremely gravelly silt loam (2) Highly organic
Family particle size	(1) Clayey (2) Clayey-skeletal (3) Sandy-skeletal
Drainage class	Well drained to excessively drained
Permeability class	Very slow
Depth to restrictive layer	15 – 84 cm
Soil depth	15 – 84 cm
Surface fragment cover <=3"	1 – 30%
Surface fragment cover >3"	2 – 50%
Available water capacity (0-101.6cm)	2.54 – 5.08 cm
Calcium carbonate equivalent (0-101.6cm)	0 – 5%
Electrical conductivity (0-101.6cm)	0 – 2 mmhos/cm
Sodium adsorption ratio (0-101.6cm)	0
Soil reaction (1:1 water) (0-101.6cm)	6.1 – 7.8
Subsurface fragment volume <=3" (0-101.6cm)	2 – 45%
Subsurface fragment volume >3" (0-101.6cm)	3 – 50%

Table 5. Representative soil features (actual values)

Drainage class	Not specified
Permeability class	Not specified
Depth to restrictive layer	Not specified
Soil depth	5 – 102 cm
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-101.6cm)	Not specified
Calcium carbonate equivalent (0-101.6cm)	Not specified
Electrical conductivity (0-101.6cm)	Not specified
Sodium adsorption ratio (0-101.6cm)	Not specified
Soil reaction (1:1 water) (0-101.6cm)	Not specified
Subsurface fragment volume <=3" (0-101.6cm)	Not specified
Subsurface fragment volume >3" (0-101.6cm)	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.

Natural Disturbances

This ecological site is in an active volcanic zone. Flows from Hualalai are a recent as A.D. 1801; the most recent Mauna Loa flow occurred in A.D. 1859. These flows may have started some fires in the vegetated areas they flowed through, but it is unlikely that the fires would have been carried far by the sparse native vegetation. Fires started by lightning are probably very rare. It is possible that strong storms may sometimes cause minor windthrow of trees.

Human Disturbances

Human-related disturbances have been more important than natural disturbances in this ecological site since the arrival of Polynesians and, later, Europeans. This is reflected in the State and Transition Model Diagram.

Humans arrived in the Hawaiian Islands 1200 to 1500 years ago. Their population gradually increased so that by 1600 AD at least 80% of all the lands in Hawaii below about 1500 feet (roughly 500 meters) in elevation had been extensively altered by humans (Kirch 1982); some pollen core data suggest that up to 100% of lowlands may have been altered (Athens 1997). By the time of European contact late in the 18th century, the Polynesians had developed high population densities and placed large areas under intensive agriculture (Cuddihy and Stone 1990). However, this ecological site was probably too dry for agriculture, except possibly burning to favor the growth of pili grass (Heteropogon contortus) used for thatching.

Prehistoric native lowland forest disturbance can be attributed to clearing for agriculture by hand or by fire, introduction of new plants, animals, possibly plant diseases, and wood harvesting. The introduced Pacific rat would have eaten bird eggs, invertebrates, and the seeds of native plants (Athens 1997).

After the arrival of Europeans, documentary evidence attests to accelerated and extensive deforestation, erosion, siltation, and changes in local weather patterns (Kirch 1983) due to more intensive land use, modern tools, and introduction of more plant, animal, and microbe species. Introduced kiawe trees (Prosopis pallida) are widespread in this ecological site.

The Polynesians introduced dogs, Pacific rats, and small pigs to the islands. After European discovery, cattle, sheep, horses, goats, and larger European pigs were introduced in the final decades of the 18th century. These animals ranged free on the islands, becoming very numerous and destructive by the early decades of the 19th century. Additionally, packs of feral dogs had become established, as confirmed by reports of their depredations on sheep. By 1851, records reported severe overstocking of pastures, lack of fences, and large numbers of feral livestock (Henke 1929).

Through the 20th and into the 21st centuries, increases in human populations with attendant land development, as well as accelerated introduction of non-native mammals (including deer), birds, reptiles, amphibians, invertebrates, plants, and microorganisms, have brought about dramatic changes to wild ecosystems in Hawaii. Much of the original forest of this ecological site has been cleared and planted with introduced grasses for livestock grazing, and the remaining native plant communities have been highly disturbed.

Since the loss of the native dry shrublands and savannas, most of this ecological site has been utilized by feral and domestic livestock, which have eliminated most unprotected native vegetation. Native plants have largely been replaced by introduced species. Introduced crimson fountaingrass (Cenchrus setaceus) spreads widely by seeds and thrives in this ecological site. It is adapted to fire, which today is ignited by humans.

State and transition model

Custom diagram

Standard diagram

Figure 7. State and Transition Model for R161AY001HI (Isohyperthermic Desert)

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 text

Ecosystem states

1. Reference State

2. Kiawe-Invaded, >25% Cover

3. Native Savanna State

T1A	-	State 1 Reference transitions to State 2 Kiawe-Invaded with lack of brush management practices or absence of fire.
R2A	-	State 2 Kiawe Invaded can be restored to State 1 Reference by applying brush management. There may be insufficient fine fuels to carry fire.

State 1 submodel, plant communities

1.1. Crimson fountaingrass with <25% kiawe cover

1.2. Crimson fountaingrass - pitted beardgrass with < 25% kiawe cover

1.3. Sweet acacia (klu)/pitted beardgrass - Bermudagrass with < 25% kiawe cover

1.1A	-	Crimson fountaingrass cover and vigor are reduced by continuous grazing, causing it to decrease and be partially replaced by less desirable forages.
1.2B	-	Phase 1.2 can change to phase 1.1 by application of a prescribed grazing program that allows crimson fountaingrass to reassume dominance. Weed control may be necessary if taller weedy forbs and/or shrubs are abundant.
1.2A	-	This community phase changes to phase 1.3 with long-term and/or heavy continuous grazing. Species composition changes to dominance by short grasses, weedy forbs, and shrubs. Bare ground increases markedly.
1.3A	-	Community phase 1.3 can change to phase 1.2 by application of a prescribed grazing program that allows crimson fountaingrass to reassume dominance. Herbicidal weed control may be necessary.

State 2 submodel, plant communities

2.1. Crimson fountaingrass with >25% kiawe cover

State 3 submodel, plant communities

3.1. Wiliwili/ekoko Erythrina sandwicense/Chamaesyce (syn. Euphorbia) celastroides

State 1
Reference State

This state consists of three community phases dominated by introduced grasses with less than 25 percent canopy cover of introduced trees. With lack of brush control or absence of wildfire, this state will transition to State 2 Kiawe-Invaded, in which production and cover of crimson fountaingrass and other forages is reduced. Accumulation of fine fuels under light or no grazing pressure increases the risk of fire. This can produce an open grassland with little tree overstory but presents a fire threat to developed areas nearby and likelihood of eroded soil entering the nearby ocean. With continuous heavy grazing, particularly by cattle, crimson fountaingrass will decrease. Koa haole and bush indigo (Indigofera suffruticosa) also will decrease under heavy grazing pressure. Increasers include swollen fingergrass (Chloris barbata), bluestems (Bothriochloa spp.), and weedy forbs. With severe deterioration, shrubby species such as lantana (Lantana camara) and apple of Sodom (Solanum linnaeaum) increase. Shortgrasses such as Bermudagrass (Cynodon dactylon) and weedy annual forbs become more abundant, as well as lesser amounts of pricklypear cactus or Barbary fig (Opuntia ficus-indica). Pricklypear cactus abundance has been limited by an introduced biocontrol insect.

Community 1.1
Crimson fountaingrass with <25% kiawe cover

Figure 8. 1.1 Kiawe Mid-Grass Desert

Crimson fountaingrass (Pennisetum setaceum) is the dominant forage species present. Kiawe (Prosopis pallida) and koa haole (Leucaena leucocephala) may be present. Kiawe is a potentially tall tree; its pods are of some forage value. If present at canopy cover greater than 25 percent, it can reduce production of grasses and forbs. Koa haole is a small tree that is browsed by livestock. Under continuous or excessively-heavy grazing, this phase will change to phase 1.2 Crimson fountaingrass-pitted beardgrass with <25% kiawe cover. Other grass species that may be present are buffelgrass (Cenchrus ciliaris) and the native species piligrass (Heteropogon contortus) and hardstem lovegrass (Eragrostis atropioides).

Resilience management. This site has a history of destructive wildfires as many areas have a high understory fine fuel build-up due to exclusion of livestock grazing. Because this site can border along the ocean, the grass should be managed to control the movement of sediment, from water erosion, to meet current and future objectives of coastal zone management. This site is maintained with prescribed grazing and suppression of wildfire.

Dominant plant species

kiawe (Prosopis pallida), tree
crimson fountaingrass (Pennisetum setaceum), grass

Figure 9. Annual production by plant type (representative values) or group (midpoint values)

Table 6. Annual production by plant type

Plant type	Low (kg/hectare)	Representative value (kg/hectare)	High (kg/hectare)
Grass/Grasslike	841	885	908
Shrub/Vine	11	28	45
Forb	11	28	45
Total	863	941	998

Figure 10. Plant community growth curve (percent production by month). HI0002, Naturalized Desert Midgrass. Shallow Desert-MLRA 157.

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
20	50	14	1	1	1	1	1	1	1	1	8

Figure 11. Plant community growth curve (percent production by month). HI1613, Isohyperthermic, Aridic – All species. The curve covers all species and life forms in MLRA 161A that occur within the isohyperthermic soil temperature regime and an aridic or dry-ustic soil moisture regime..

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
30	28	11	1	1	1	1	1	1	1	8	16

Community 1.2
Crimson fountaingrass - pitted beardgrass with < 25% kiawe cover

This community phase consists of lower-value grass species that become abundant upon continuous heavy grazing of crimson fountaingrass. Further overgrazing exacerbates this process, causing a community change to phase 1.3. An overstory of kiawe (Prosopis pallida) may be present at up to 25 percent canopy cover. Pitted beardgrass (Bothriochloa pertusa) and swollen fingergrass (Chloris barbata) have both increased in cover and production. Crimson fountaingrass (Cenchrus setaceus) is much reduced. Koa haole is much reduced compared with phase 1.1. Unpalatable species such as uhaloa (Waltheria indica), Japanese tea (Chamaecrista nictitans), Australian saltbush (Atriplex semibaccata), and golden crownbeard (Verbesina encelioides) have increased.

Dominant plant species

crimson fountaingrass (Pennisetum setaceum), grass
pitted beardgrass (Bothriochloa pertusa), grass

Figure 12. Plant community growth curve (percent production by month). HI1613, Isohyperthermic, Aridic – All species. The curve covers all species and life forms in MLRA 161A that occur within the isohyperthermic soil temperature regime and an aridic or dry-ustic soil moisture regime..

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
30	28	11	1	1	1	1	1	1	1	8	16

Community 1.3
Sweet acacia (klu)/pitted beardgrass - Bermudagrass with < 25% kiawe cover

This community phase consists mostly of grass species that are highly tolerant of grazing, particularly Bermudagrass, along with increased amounts of unpalatable shrubs, forbs, and subshrubs. Koa haole is gone or is browsed down to stumps. Bare ground is extensive, so soil erosion by wind and water can be excessive. An overstory of kiawe (Prosopis pallida) may be present at up to 25 percent canopy cover. The most abundant grass species are pitted beardgrass (Bothriochloa pertusa) and Bermudagrass (Cynodon dactylon). Sweet acacia or klu (Acacia farnesiana) is an unpalatable shrub. Some native aalii (Dodonaea viscosa), ilima (Sida cordifolia), and uhaloa (Waltheria indica) typically are present.

Dominant plant species

sweet acacia (Acacia farnesiana), tree
pitted beardgrass (Bothriochloa pertusa), grass
Bermudagrass (Cynodon dactylon), grass

Figure 13. Plant community growth curve (percent production by month). HI1613, Isohyperthermic, Aridic – All species. The curve covers all species and life forms in MLRA 161A that occur within the isohyperthermic soil temperature regime and an aridic or dry-ustic soil moisture regime..

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
30	28	11	1	1	1	1	1	1	1	8	16

Pathway 1.1A
Community 1.1 to 1.2

Crimson fountaingrass cover and vigor are reduced by continuous grazing, causing it to decrease and be partially replaced by less desirable forages.

Pathway 1.2B
Community 1.2 to 1.1

Phase 1.2 can change to phase 1.1 by application of a prescribed grazing program that allows crimson fountaingrass to reassume dominance. Weed control may be necessary if taller weedy forbs and/or shrubs are abundant.

Conservation practices

Prescribed Grazing

Pathway 1.2A
Community 1.2 to 1.3

This community phase changes to phase 1.3 with long-term and/or heavy continuous grazing. Species composition changes to dominance by short grasses, weedy forbs, and shrubs. Bare ground increases markedly.

Pathway 1.3A
Community 1.3 to 1.2

Community phase 1.3 can change to phase 1.2 by application of a prescribed grazing program that allows crimson fountaingrass to reassume dominance. Herbicidal weed control may be necessary.

State 2
Kiawe-Invaded, >25% Cover

This state consists of one community phase. It occurs when brush management has not been practiced or if fire has not occurred for a long time, allowing kiawe to increase in density and stature to a level at which understory production is competitively reduced.

Community 2.1
Crimson fountaingrass with >25% kiawe cover

Kiawe canopy cover is 25 percent or higher. The understory consists of remnant crimson fountaingrass and other grasses. This plant community is poor for livestock grazing due to reduced forage amounts beneath the dense tree canopy. Bare ground has increased, and there may be shallow, seasonal stream channels cut into the soil.

Dominant plant species

kiawe (Prosopis pallida), tree
crimson fountaingrass (Pennisetum setaceum), grass

Figure 14. Plant community growth curve (percent production by month). HI1613, Isohyperthermic, Aridic – All species. The curve covers all species and life forms in MLRA 161A that occur within the isohyperthermic soil temperature regime and an aridic or dry-ustic soil moisture regime..

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
J	F	M	A	M	J	J	A	S	O	N	D
30	28	11	1	1	1	1	1	1	1	8	16

State 3
Native Savanna State

This state consists of one community phase. Intact examples of this community no longer exist. This description is compiled from field observations of remnant vegetation, isolated plants on disturbed sites, a similar ecological site on the Island of Hawaii, and historical accounts.

Community 3.1
Wiliwili/ekoko Erythrina sandwicense/Chamaesyce (syn. Euphorbia) celastroides

The hypothetical appearance of this community phase is an open canopy of low to medium height (15-25 feet; 4.5 to 8 meters) trees, a shrub understory, and a ground layer of vines, herbs, and grasses. The species present would be typical of other low elevation dry Hawaiian sites. Among the common tree species would be wiliwili (Erythrina sandwicensis), ohe makai (Polyscias sandwicensis), lama (Diospyros sandwicensis), hao (Rauvolfia sandwicensis), and alahee (Psydrax odoratum). Some common shrubs would be maiapilo or native caper (Capparis sandwichiana), aheahea (Chenopodium oahuense), ekoko (Euphorbia spp.), mao or Hawaiian cotton (Gossypium tomentosum), iliahi (Santalum ellipticum), and ilima (Sida fallax). Some common vines would be dodder (Cuscuta campestris), pauohiiaka (Jacquemontia sandwicensis), and oceanblue morning-glory (Ipomoea indica). Many forbs, grasses, and grasslike species would be present.

Dominant plant species

wili wili (Erythrina sandwicensis), tree
'ekoko (Chamaesyce celastroides), shrub

Transition T1A
State 1 to 2

State 1 Reference transitions to State 2 Kiawe-Invaded with lack of brush management practices or absence of fire.

Restoration pathway R1A
State 1 to 3

State 1 Naturalized Grassland can be restored to a facsimile of State 3 Native Forest. Fire and ungulates must be excluded. Crimson fountaingrass and other non-native vegetation must be killed by applying aggressive weed control measures, followed by plantings of native trees, shrubs, and vines. Supplemental irrigation may be necessary in the early stages of restoration.

Restoration pathway R2A
State 2 to 1

State 2 Kiawe Invaded can be restored to State 1 Reference by applying brush management. There may be insufficient fine fuels to carry fire.

Conservation practices

Brush Management
Prescribed Grazing

Transition T3A
State 3 to 1

State 3 Native Forest transitions to State 1 Naturalized Grassland when cleared by fire, long-term ungulate disturbance, or mechanical means. Crimson fountaingrass would re-establish from nearby sites.

Additional community tables

Table 7. Community 1.1 plant community composition

Group	Common name	Symbol	Scientific name	Annual production (kg/hectare)	Foliar cover (%)
Grass/Grasslike
1	Naturalized Warm Season Mid Bunch Grasses			807–897
	crimson fountaingrass	PESE3	Pennisetum setaceum	809–857	–
	buffelgrass	PECI	Pennisetum ciliare	1–47	–
2	Naturalized Warm Season Short Bunch Grasses			1–47
	pitted beardgrass	BOPE2	Bothriochloa pertusa	1–9	–
	swollen fingergrass	CHBA10	Chloris barbata	1–9	–
	rose Natal grass	MERE9	Melinis repens	1–9	–
3	Naturalized Warm Season Short Stoloniferous			1–9
	Bermudagrass	CYDA	Cynodon dactylon	1–9	–
4	Native Warm Season Mid Bunch Grasses			1–47
	hardstem lovegrass	ERAT	Eragrostis atropioides	1–9	–
	tanglehead	HECO10	Heteropogon contortus	1–9	–
Forb
5	Naturalized Forbs			9–47
	uhaloa	WAIN	Waltheria indica	1–47	–
	sensitive partridge pea	CHNI2	Chamaecrista nictitans	1–9	–
Shrub/Vine
6	Naturalized Shrubs, Half-Shrubs and Trees			9–47
	kiawe	PRPA4	Prosopis pallida	7–47	–
	‘ilima	SICO	Sida cordifolia	1–9	–
	sweet acacia	ACFA	Acacia farnesiana	1–9	–
	white leadtree	LELE10	Leucaena leucocephala	1–9	–

Interpretations

Animal community

Animal Community - Wildlife Interpretations
This site may be better suited for wildlife habitat, as a major use, due to the reasons stated in the Grazing Interpretations section. This site provides habitat to a variety of small and medium-sized introduced birds such as doves, Northern cardinal, the chestnut-bellied sandgrouse, and the gray francolin. Because of its open savannah aspect, this site provides habitat for other important wildlife such as the Hawaiian hawk and the Hawaiian owl.

Animal Community - Grazing Interpretations
The following table lists suggested initial stocking rates for cattle under the Forage Value Rating system for the interpretive plant community, only. These are conservative estimates that should be used only as guidelines in the initial stages of the conservation planning process. Often, the current plant composition does not entirely match any particular plant community (described in this ecological site description). Because of this, a field visit is recommended, in all cases, to document plant composition and production. More precise carrying capacity estimates should eventually be calculated using the following stocking rate information along with animal preference data, particularly when grazers other than cattle are involved. Under more intensive grazing management, improved harvest efficiencies can result in an increased carrying capacity.

Forage Value Rating (1): Very High(2)
Acre/AUM(3): 2.6-3.0
AUM/Acre(3): 0.40-0.33

Forage Value Rating (1): High
Acre/AUM(3): 3.0-3.7
AUM/Acre(3): 0.33-0.27

Forage Value Rating (1): Moderate
Acre/AUM(3): 3.7-6.2
AUM/Acre(3): 0.27-0.16

Forage Value Rating (1): Low
Acre/AUM(3): 6.2- +
AUM/Acre(3): 0.16- +

(1) The Forage Value Rating System is not an ecological evaluation of the naturalized plant community. It is a utilitarian rating of the existing forage value of a specific tract of naturalized rangeland.
(2) Conservationists must use considerable judgement, because in places an are, in the Very High forage class, could be producing less than normal volumes of forage, and adjustments would need to be made in the initial stocking rate.
(3) Stocking rates vary in accordance with such factors as kind and class of livestock or wildlife, season of use, and fluctuations in climate. Actual use records and on-site inventories for individual rangeland ecological sites, together with a determination of the degree to which the sites have been grazed, offer the most reliable basis for developing initial stocking rates.

The naturalized plant community on this site is suitable for grazing by all kinds and classes of livestock, at any season, particularly cattle. However, this site is best utilized for mid-fall to late winter grazing as this is the major plant growth period. This site is suited for grazing by both cow-calf operations and stocker operations. However, sheep can be grazed on this site as well. This site is poorly suited to continuous year-long use if the interpretive naturalized plant community is to be maintained. This site does have restrictions and limitations. This site, in many instances, is surrounded by rough, bare lava flows. The access into the site and handling of livestock thereafter can be difficult. As a result, roads or livestock trails would have to be constructed, and this could prove to be economically infeasible. The installation of livestock water developments may not prove to practical, due to the same reasons. Herbaceous forage can be deficient in protein during the drier summer months.

Hydrological functions

Soil depth is the principal factor limiting forage production on this site. This site is dominated by soils in hydrologic group D. Infiltration and runoff potential for this site varies from very low to moderate depending on soil hydrologic group and ground cover. Areas where ground cover is less than 50% have the greatest potential to have reduced infiltration and higher runoff (refer to Section 4, NRCS National Engineering Handbook (NEH-4) for runoff quantities and hydrologic curves).

Recreational uses

This site may be better suited to recreation, as a major use, rather than livestock grazing, due to the reasons stated in the Grazing Interpretations section. Because of the climate of the major land resource area, the open savannah nature of the site, and the surrounding and adjacent rough, bare lava flows, it composes a significant part of the charm and character of West Hawaii. The naturalized grass and shrub species make this site pleasing to view. Its open aspect make it an excellent location for hiking, bird watching, hunting, and viewing the sharply contrasting black lava flows. The open space nature of this site is currently being threatened, in some areas, due to the development of subdivisions.

Other products

None

Other information

None

Supporting information

Type locality

Location 1: Hawaii County, HI
Township/Range/Section	TN/A RN/A SN/A
General legal description	General Description: Hawaii County, Island of Hawaii, North Kona District. 19o 54’ 34” N. Latitude, 155o 52’ 07” W. Longitude. USGS Quad: Puu Hinai. East of power substation along State Highway 19; opposite of Waikoloa Resort.

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. 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.

Aridic soil moisture regime: A regime in which defined parts of the soil are, in normal years, dry for more than half of the growing season and moist for less than 90 consecutive days during the growing season. In Hawaii it is associated with hot, dry areas with plants such as kiawe, wiliwili, and crimson fountaingrass. The terms aridic and torric are basically the same.

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.

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.

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

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

Medial: A “soil texture modifier” for volcanic ash soils having a water content at the crop wilting point of 30 to 100 percent; a soil that holds an amount of water intermediate to “hydrous” or “ashy” soils.

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.

Torric soil moisture regime: See Aridic soil moisture regime.

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 Auweloa
Lori Metz
Jennifer Higashino
Mathew Cocking
Amy Koch
Kendra Moseley

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
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	04/24/2025
Approved by	Kendra Moseley
Approval date
Composition (Indicators 10 and 12) based on	Annual Production