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Ecological site VX166X01X501

Placorthod Forest

Last updated: 5/08/2025
Accessed: 12/07/2025

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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): 166X–Very Stony Land and Rock Land

This MLRA occurs in the State of Hawaii on the islands of Maui, Kahoolawe, Lanai, Molokai, Oahu, Kauai, and Niihau. Elevation ranges from sea level to 8,000 feet (0 to 2,440 meters). The terrain encompasses stony complex slopes and rocky gulches (USDA-NRCS, 2006). The geology is extrusive basic igneous rock (primarily basalt) that are weathered in some areas. Some interfluves are mantled with weathered volcanic ash. Average annual precipitation ranges from 17 to 39 inches (430 to 990 millimeters) (Giambelluca et al., 2013). Extreme average annual precipitation ranges from 10 to 107 inches (254 to 2,720 millimeters). Most of the rainfall occurs from November through March, much of it during kona storms. Average annual air temperatures ranges from 70 to 75 degrees F (21 to 24 degrees C) with little seasonal variation (Giambelluca et al., 2014). Extreme annual air temperatures range from 48 to 82 degrees F (9 to 28 degrees C). Dominant soils are Mollisols, Aridisols, and Entisols with an isohyperthermic, isothermic, or isomesic soil temperature regimes and ustic or aridic soil moisture regimes (USDA-NRCS, 2006). Vegetation consists of forbs, grasses, and shrubs with some trees. Most of the plant species typically encountered are introduced species that have become naturalized in Hawaii. However, areas within this MLRA are critical habitat for rare, threatened, or endangered plant species.

Classification relationships

This ecological site occurs within Major Land Resource Area (MLRA) 166 - Very Stony Land and Rock Land.

The Aha Moku System, which dates back to the 9th century and has been passed down through oral tradition and generational wisdom, effectively sustains Hawaii's natural ecosystems and environment (DLNR, 2024). This site-specific and resource-based approach balances land and ocean resources essential for fostering healthy, thriving communities. Grounded in Native Hawaiian generational knowledge, the Aha Moku System emphasizes community consultation to prioritize the health and welfare of Hawaii’s natural and cultural resources. It is rooted in the concept of 'ahupua'a, the traditional system of land and ocean management in Hawaii. For collaboration, this ecological framework encompasses the following mokus:

Molokai Moku Acres: Kona (1,691) and Ko’olau (200).

Lanai Moku Acres: Lahaina (316).

Ecological site concept

This ecological site is forest on the moist, narrow ridgetops of Lanai and the ridgetops and upper slopes of the east Molokai mountains. It is within state lands. There is limited access on Lanai along the Lanaihale trail. Access on Molokai is limited to trails.

An ironstone sheet or placic horizon which is impermeable to roots and water occurs at about 21 inches (53 centimeters) depth (USDA-SCS, 1972). The soils are very strongly acid (pH 4.5 to 4.8) throughout. It is this shallow, impermeable, placic horizon combined with the acidic nature of these soils which results in soils that have low water holding capacity and low nutrient availability. As such, the native vegetation is expressed as a low to medium stature rain forest with gnarled, many-branched trees, lots of shrubs and ferns, and many epiphytes (Hawaii Division of Forestry and Wildlife, 1991; Hobdy, 1993; Liebherr, 2009; Wagner et al., 1999; Wood, 1998). Rainfall is well distributed throughout the year and is supplemented by fog drip (Ekern, 1964).

Associated sites

VX158X01X005	Naturalized Grassland 50 to 90 inch PZ Ohia lehua/kikuyugrass (Metrosideros polymorpha/Pennisetum clandestinum) The Naturalized Grassland 50 to 90 Inch Precipitation Zone Ecological Site (R158XY005HI) co-occurs with this ecological site on Molokai. It occurs at lower and drier elevations which lacks the shallow ironstone layer of this ecological site. It supports vegetation that is transitional between dry and moist habitat types rather than the gnarled, low stature rainforest of this ecological site.
VX164X01X004	Epiaquic Forest The Epiaquic Forest Ecological Site (F164XY004HI) is adjacent to this ecological site on Molokai, where it generally occurs at higher and wetter elevations than this ecological site. Both sites have a shallow ironstone layer, but the Epiaquic Forest is poorly drained rather than well drained, causing gleyed soils that are lacking in this ecological site. The two ecological sites share some species, but the Epiaquic Forest should have more obligate wetland species and more a more open, shorter stature overstory than this ecological site.

VX158X01X005

Naturalized Grassland 50 to 90 inch PZ Ohia lehua/kikuyugrass (Metrosideros polymorpha/Pennisetum clandestinum)

The Naturalized Grassland 50 to 90 Inch Precipitation Zone Ecological Site (R158XY005HI) co-occurs with this ecological site on Molokai. It occurs at lower and drier elevations which lacks the shallow ironstone layer of this ecological site. It supports vegetation that is transitional between dry and moist habitat types rather than the gnarled, low stature rainforest of this ecological site.

VX164X01X004

Epiaquic Forest

The Epiaquic Forest Ecological Site (F164XY004HI) is adjacent to this ecological site on Molokai, where it generally occurs at higher and wetter elevations than this ecological site. Both sites have a shallow ironstone layer, but the Epiaquic Forest is poorly drained rather than well drained, causing gleyed soils that are lacking in this ecological site. The two ecological sites share some species, but the Epiaquic Forest should have more obligate wetland species and more a more open, shorter stature overstory than this ecological site.

Similar sites

VX164X01X001	Gleyed Soil Forest The Gleyed Soil Forest Ecological Site (F164XY001HI) is similar to this ecological site because both sites have a shallow to somewhat shallow ironstone layer that is impermeable to roots and water, and both have forests which are stunted in stature (short or medium). F164XY001HI differs by occurring at higher elevations where conditions are wetter and by having soils comprised of poorly drained peat or muck, underlain by gleyed (gray and anaerobic) silty clay, while this ecological site has well drained soils formed from material weathered from basic igneous rock.

VX164X01X001

Gleyed Soil Forest

The Gleyed Soil Forest Ecological Site (F164XY001HI) is similar to this ecological site because both sites have a shallow to somewhat shallow ironstone layer that is impermeable to roots and water, and both have forests which are stunted in stature (short or medium). F164XY001HI differs by occurring at higher elevations where conditions are wetter and by having soils comprised of poorly drained peat or muck, underlain by gleyed (gray and anaerobic) silty clay, while this ecological site has well drained soils formed from material weathered from basic igneous rock.

Table 1. Dominant plant species

Tree	(1) Metrosideros polymorpha (2) Cheirodendron trigynum
Shrub	(1) Freycinetia arborea
Herbaceous	Not specified

Legacy ID

F166XY501HI

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Physiographic features

This ecological site occurs on weathered basaltic lava flows on ridges and upper mountain slopes (USDA-SCS, 1972).

Table 2. Representative physiographic features

Landforms	(1) Shield volcano > Ridge (2) Shield volcano > Mountain slope
Runoff class	Medium to high
Flooding frequency	None
Ponding frequency	None
Elevation	1,250 – 3,750 ft
Slope	3 – 20%
Water table depth	72 in
Aspect	E, S

Table 3. Representative physiographic features (actual ranges)

Runoff class	Not specified
Flooding frequency	Not specified
Ponding frequency	Not specified
Elevation	600 – 3,750 ft
Slope	Not specified
Water table depth	Not specified

Climatic features

SUMMARY FOR THIS ECOLOGICAL SITE
Rainfall statistics were determined from University of Hawaii's Rainfall Atlas Raster Data (Giambelluca et al., 2013). Most of the precipitation falls from October through April. Representative (20th and 80th percentiles) values for annual average precipitation range from 56 to 100 inches (142 to 254 centimeters) while actual (10th and 90th percentiles) values range from 35 to 101 inches (89 to 257 centimeters). Extreme values range from 29 to 105 inches (74 to 267 centimeters). The mean annual precipitation is 74 inches (188 centimeters), and the median annual average precipitation is also 74 inches (188 centimeters). Landscapes are shrouded in fog or overcast during much of the day throughout the year, which reduces evapotranspiration and adds additional moisture from condensation of fog on vegetation, possibly as much as equaling the amount from rainfall (Ekern, 1964; Juvik and Nullett, 1993). Located in the rain shadow of Maui, Lanai is relatively dry. A large portion of the water in the island’s aquifer comes from fog drip pulled from clouds by trees and ferns in upper elevations.

Temperature statistics were determined from University of Hawaii's Surface Temperature Raster Data (Giambelluca et al., 2014). Representative (20th and 80th percentiles) values for annual temperatures range from 63 to 70 degrees F (17 to 21 degrees C) while actual (10th and 90th percentiles) values range from 63 to 72 degrees F (17 to 22 degrees C). Extreme values range from 60 to 73 degrees F (16 to 23 degrees C). The mean annual temperature is 66 degrees F (19 degrees C) and the median annual temperature is also 66 degrees F (19 degrees C).

No suitable Western Region Climate Stations occur in or near this ecological site (WRCC, 2020). The data in the climate normals tables below are from the University of Hawaii.

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).

The islands lie within the trade wind zone. Significant amounts of moisture are picked up from the ocean by trade winds up to an altitude of more than about 6,000 feet (1,829 meters). As the trade winds from the northeast are forced up the mountains of the islands their moisture condenses, creating rain on the windward slopes; the leeward sides of the island receive little of this moisture (USDA-SCS, 1972; Western Regional Climate Center, 2020).

Hawaiian indigenous understanding recognized two seasons: Kau or Kauwela (dry season), and Ho`oilo (wet season). During Kau, the sun is directly overhead, days are long and warm, and the trade winds are stronger and more consistent; Kau started on the first new moon in May when the Pleiades set at sunrise (Handy et al., 1991). During Ho’oilo (wet season) the sun is declined toward the south, days are shorter, temperatures cooler and winds more variable and generally started with the first new moon in November. Ho’oilo is also the season when extensive low-pressure systems often approach the islands from the west, producing heavy rainstorms that primarily affect the leeward sides, but can envelope the entire island. (Malo, 1903; Handy et al., 1991; Sanderson, 1993). Differences in rainfall amounts between winter and summer are most marked in low elevation dry areas; wetter areas exhibit less seasonal variation in rainfall (USDA-SCS, 1972; Western Regional Climate Center, 2020).

On the windward sides of the islands, cool, moist air at higher elevations descends toward the ocean where it meets the trade winds; this process brings rainfall, often at night, to lower elevation areas (USDA-SCS, 1972; Western Regional Climate Center, 2020).

Extensive low-pressure systems often approach the islands from the west, producing heavy rainstorms that primarily affect the leeward sides, but can envelope the entire island. These major storms occur most frequently between October and March (USDA-SCS, 1972; Western Regional Climate Center, 2020).

Because Lanai is small and relatively smooth, the geographic distribution of its rainfall is not as spotty as on the larger rugged islands. Rainfall varies widely from year to year. There is a well-marked dry season during summer. December is the wettest month and July the driest in most locations. Heavy downpours during a single kona storm commonly account for a considerable part of the annual rainfall, and in some of the arid sections a single rain may contribute as much as 80 percent of the annual total. Because the island is not sheltered by other islands on the southerly side, kona storms are unobstructed. Sudden local heavy showers called naulu fall during times when neither the trade winds nor the kona winds blow. A naulu shower is caused by a cloud that forms off the south or west coast and then moves inland, dropping its moisture apparently as a result of local convection currents. Naulu showers are reported to occur chiefly in the afternoon during hot weather. Strong trade winds funneled from Maui and Molokai increase evaporation of moisture and contribute to soil erosion, particularly on the western side of Lanai (Hobdy, 1993; Western Regional Climate Center, 2020).

Table 4. Representative climatic features

Frost-free period (characteristic range)	365 days
Freeze-free period (characteristic range)	365 days
Precipitation total (characteristic range)	56-100 in
Frost-free period (actual range)	365 days
Freeze-free period (actual range)	365 days
Precipitation total (actual range)	35-101 in
Frost-free period (average)	365 days
Freeze-free period (average)	365 days
Precipitation total (average)	74 in

Soil features

Only one soil component (Kahanui) is associated with this ecological site.

Kahanui soils are classified Placorthods. This series consists of moderately deep (but nearly in the shallow depth category), well drained silty clay that formed in material weathered from basic igneous rock (USDA-SCS, 1972). There is a weakly developed ironstone sheet at about 21 inches (52 centimeters) depth which is impermeable to roots and water except through cracks. The soil temperature regime is isothermic, and the soil moisture regime is udic. Soil reaction is very strongly acid (pH 4.5 to 4.8) throughout.

Table 5. Representative soil features

Parent material	(1) Igneous rock
Surface texture	(1) Silty clay (2) Gravelly silty clay
Family particle size	(1) Very-fine
Drainage class	Well drained
Permeability class	Very slow
Depth to restrictive layer	21 in
Soil depth	21 – 72 in
Surface fragment cover <=3"	Not specified
Surface fragment cover >3"	Not specified
Available water capacity (0-40in)	2 in
Calcium carbonate equivalent (0-40in)	Not specified
Electrical conductivity (0-40in)	Not specified
Sodium adsorption ratio (0-40in)	Not specified
Soil reaction (1:1 water) (0-10in)	4.5 – 4.8
Subsurface fragment volume <=3" (0-40in)	3 – 16%
Subsurface fragment volume >3" (0-40in)	2%

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

Possible natural disturbances are drought, hurricanes and, in some locations, landslides (Hobdy, 1993).

HUMAN DISTURBANCES

Humans arrived in the Hawaiian Islands 1,200 to 1,500 years ago. Their population gradually increased so that by 1,600 A.D. at least 80 percent of all the lands in Hawaii below about 1,500 feet (457 meters) in elevation had been extensively altered by humans (Kirch, 1982). This ecological site occurs well above that elevation. However, this ecological site may have been affected by factors such as inadvertently introduced plant diseases and seed predation by the introduced Pacific Rat (Athens, 1997).

Approximately 50 percent (1,276 acres) of this 2,549-acre ecological site overlaps with the modeled "Intensive Agroforestry" agroecological system (Lincoln et al., 2023). Intensive Agroforestry was a managed tree cropping system which resulted in native forests becoming “replaced over time by Polynesian introduced trees, such as ‘ulu (breadfruit), kukui (candlenut), and ‘ohi‘a‘ai (mountain apple; Syzygium malaccense), along with some shade tolerant crops and native species in the understory (Handy et al., 1972; Meilleur et al., 2004; Lincoln, 2020)” (Lincoln et al., 2023, p. 06).

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.

The Polynesians introduced dogs, Pacific rats, and small pigs to the islands. 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 (Henke, 1929). The most destructive introduced animals in this remote ecological site have been feral pigs and cattle.

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, birds, reptiles, amphibians, invertebrates, plants, and microorganisms, have brought about dramatic changes to wild ecosystems in Hawaii.

The main disturbances in this ecological site are due to feral pigs, deer, mouflon sheep, and goats that disturb the soil and directly consume native plants and rats that consume seeds. Some plant species introduced since the arrival of Europeans in Hawaii thrive in this ecological site and have spread rapidly over large areas, competing with native plants. Common invasive plant species are the shrub soapbush or Koster’s curse (Clidemia hirta), strawberry guava (Psidium cattleianum), firetree or faya (Morella faya), broom teatree or manuka (Leptospermum scoparium), and grey sheoak or longleaf ironwood (Casuarina glauca). The forb Colombian waxweed (Cuphea carthagenensis) is present. West Indian raspberry (Rubus rosifolius) is common. Some common introduced and invasive grass and sedges are hilograss (Paspalum conjugatum) and glenwoodgrass (Sacciolepis indica) (Hawaii Division of Forestry and Wildlife, 1991; Hobdy, 1993; Liebherr, 2009; Wagner et al., 1999; Wood, 1998).

State and transition model

Custom diagram

Standard diagram

Figure 1. State-and-transition model diagram for the Placorthod Forest (F166XY501HI)

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. Weed-Invaded State

T1A	-	The Reference State (1) transitions to the Weed-Invaded State (2) by invasion of introduced plant species. Disturbance by feral deer, goats, mouflon sheep, and pigs will hasten this process, as will landslides and hurricanes.
R2A	-	Restoration of the Weed-Invaded State (2) to the Reference State (1) or a facsimile of it may be possible by installing ungulate-proof fence, removing all ungulates, removing introduced plant species, and replanting native species when needed. Long term weed management and fence maintenance would be necessary.

State 1 submodel, plant communities

1.1. 'Ohi'a Lehua – Olapa/'Ie'ie

State 2 submodel, plant communities

2.1. Firetree (Faya) - Strawberry Guava/Soapbush (Koster's Curse)

State 1
Reference State

The Reference State (1) is comprised of one community phase. With disturbance from hurricanes, landslides, or introduced mammals, invasive plants invade the site and native plant species decline in abundance. Invasive plants may invade the site without other disturbances, but the process is much slower.

Community 1.1
'Ohi'a Lehua – Olapa/'Ie'ie

The vegetation of this community phase is rainforest of low to medium stature with gnarled, many-branched trees, lots of shrubs and ferns, and many epiphytes. Lichens and mosses are abundant on tree trunks and branches. Among others, trees may include 'Ohi'a lehua (Metrosideros plymorpha), olapa (Cheirodendron forbesii), ha’a (Antidesma platyphyllum), and Hawai'i holly or kawau or (Ilex anomala). A midstory of tree ferns including hapu’u (Cibotium glaucum) and hapu’u li (Cibotium menziesii) may occur. Shrubs include but are not limited to kanawao (Broussaisia arguta), bog clermontia (Clermontia grandiflora), Maui mirrorplant or pilo (Coprosma ochracea), and pukiawe (Styphelia tameiameiae). Forbs may include Hawai’i jeweled orchid (Anoectochilus sandvicensis), pua’akuhinia (Astelia menziesiana), Hawai’i widelip orhchid (Liparis hawaiensis), lobelia (Lobelia spp.), and Peperomia or ‘ala’ala wai nui (Peperomia spp). Vines may include 'ie'ie (Freycinetia arborea) and Hawai’i greenbrier or hoi kuahiwi (Smilax melastomifolia). Grass and grasslike plants may include alpine hairgrass (Deschampsia nubigena) and Polynesian twigrush (Machaerina angustifolia) (Wagner et al., 1999).

Dominant plant species

'ohi'a lehua (Metrosideros polymorpha), tree
olapa (Cheirodendron forbesii), tree
'ie'ie (Freycinetia arborea), shrub

State 2
Weed-Invaded State

The Weed-Invaded State (2) is comprised of one community phase. It comes into being by gradual invasion of introduced species. Disturbance of the soil and direct damage to native plants by introduced ungulates, particularly pigs, goats, and deer, will facilitate the transition to this state.

Community 2.1
Firetree (Faya) - Strawberry Guava/Soapbush (Koster's Curse)

The vegetation consists of low to medium stature trees with a diverse understory. Native species are present but have been partially or, in places, wholly displaced by introduced species. Common invasive plant species are the shrub soapbush or Koster’s curse (Clidemia hirta), strawberry guava (Psidium cattleianum), firetree or faya (Morella faya), broom teatree or manuka (Leptospermum scoparium), and gray sheoak or longleaf ironwood (Casuarina glauca). The forb Colombian waxweed (Cuphea carthagenensis) is present. West Indian raspberry (Rubus rosifolius) is common. Some common introduced and invasive grass and sedges are hilograss (Paspalum conjugatum) and glenwoodgrass (Sacciolepis indica).

Dominant plant species

firetree (Morella faya), tree
strawberry guava (Psidium cattleianum), tree
soapbush (Clidemia hirta), shrub

Transition T1A
State 1 to 2

The Reference State (1) transitions to the Weed-Invaded State (2) by invasion of introduced plant species. Disturbance by feral deer, goats, mouflon sheep, and pigs will hasten this process, as will landslides and hurricanes.

Restoration pathway R2A
State 2 to 1

Restoration of the Weed-Invaded State (2) to the Reference State (1) or a facsimile of it may be possible by installing ungulate-proof fence, removing all ungulates, removing introduced plant species, and replanting native species when needed. Long term weed management and fence maintenance would be necessary.

Additional community tables

Supporting information

Other references

REFERENCES for F166XY501HI Placorthod Forest

Athens, J.S. (1997). Prehistoric environmental and landscape change. In Kirch, P.V. & T.L. Hunt (Eds.), Hawai’ian native lowland vegetation in the Pacific Islands (Pgs. 248 -270). Yale University Press. [https://www.pelagicos.net/BIOL3010/readings/Athens_1997.pdf].

Department of Land and Natural Resources (2024). Hawai’i State Aha Moku. [https://dlnr.hawaii.gov/ahamoku/councils/].

Ekern, P. C. (1964). Direct interception of cloud water on Lanaihale, Hawaii. Soil Science Society of America Proceedings 28:419-421.

Giambelluca, T.W., Q. Chen, A.G. Frazier, J.P. Price, Y.L. Chen, P.-S. Chu, J.K. Eischeid, & D.M. Delparte. (2013): Online rainfall atlas of Hawai’i. Bull. Amer. Meteor. Soc. 94, 313-316, DOI: [https://doi.org/10.1175/BAMS-D-11-00228.1].

Giambelluca, T.W., X. Shuai, M.L. Barnes, R.J. Alliss, R.J. Longman, T. Miura, Q. Chen, A.G. Frazier, R.G. Mudd, L. Cuo, & A.D. Businger. (2014). Evapotranspiration of Hawai’i. Final report submitted to the U.S. Army Corps of Engineers - Honolulu District, and the Commission on Water Resource Management, State of Hawai’i. [https://www.hawaii.edu/climate-data-portal/evapotranspiration-atlas/].

Handy, E.S.C., E.G. Handy, & Pukui, M.K. (First Edition 1972, Revised Edition 1991). Native planters in old Hawai’i: Their life, lore, and environment. Bishop Museum Press.

Hawaii Division of Forestry and Wildlife. (1991). Olokui natural area reserve management plan. Department of Land & Natural Resources, natural area reserves system program, State of Hawaii.

Henke, L.A. (1929). A survey of livestock in Hawai’i. Research Publication No. 5. University of Hawai’i, Honolulu. [https://www.ctahr.hawaii.edu/oc/freepubs/pdf/RP-5.pdf].

Hobdy R. (1993). Lanai - A case study: The loss of biodiversity on a small Hawai’ian island. Pacific Science 47, 3:201-210.

Juvik, J.O., & Nullett, D. (1993). A climate transect through tropical montane rain forests in Hawai’i. Department of Geography, University of Hawai’i at Hilo, Hilo Hawai’i. Journal of Applied Meteorology. Volume 33.

Kirch, P.V. (1982). The impact of the prehistoric Polynesians in the Hawai’ian ecosystem. Pacific Science 36 (1):1-14.

Kirch, P.V. (1983). Introduction. In Archaeological investigations of the Mudlane-Waimea-Kawaihae Road Corridor, Island of Hawai’i: An Interdisciplinary Study of an Environmental Transect. Clark, J.T. and Kirch, P.V., eds. Dept. of Anthropology, Bernice Pauahi Bishop Museum, Report 83-1, Honolulu, HI.

Liebherr J.K. (2009). Native and alien Carabidae (Coleoptera) share lanai, an ecologically devastated island. The Coleopterists Bulletin, 63(4):383-411. General discussion of vegetation and disturbance history on Lanai.

Lincoln, N. K. (2020). Agroforestry form and ecological adaptation in ancient
Hawai’i: extent of the pakukui swidden system of Hamakua, Hawai’i Island. Agric. Syst.
181, 102808. doi: [https://doi.org/10.1016/j.agsy.2020.102808].

Lincoln, N.K, T.P. Haensel, & Lee, T.M. (2023). Modeling Hawai’ian agroecology: Depicting traditional adaptation to the world’s most diverse environment. Frontiers in Sustainable Food Systems. Climate-Smart Food Systems. Volume 7 – 2023. Pg. 06.
[https://doi.org/10.3389/fsufs.2023.1116929].

Malo, D. (1903). Hawaiian antiquities. N.B. Emerson (trans.). Bishop Museum Special Publication 2. Honolulu.

Meilleur, B. A., Jones, R. R., Titchenal, C. A., and Huang, A. S. (2004). Hawaiian Breadfruit: Ethnobotany, Nutrition, and Human Ecology. Honolulu, HI: College of Tropical Agriculture and Human Resources, University of Hawai’i.

Sanderson, M. (ed.). (1993). Prevailing trade winds, weather and climate in Hawai’i. University of Hawai’i Press. Honolulu.

U.S. Department of Agriculture, Natural Resources Conservation Service. (2006). Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. United States Department of Agriculture, Agriculture Handbook 296. [https://www.nrcs.usda.gov/sites/default/files/2022-10/AgHandbook296_text_low-res.pdf].

U.S. Department of Agriculture, Soil Survey Conservation Service. (1972). Soil survey of Islands of Kauai, Oahu, Maui, Molokai, and Lanai, State of Hawai’i. Foote D.E., Hill E.L., Nakamura S., & F. Stephens, in cooperation with The University of Hawai’i Agricultural Experiment Station.

U. S. Department of Interior, Fish & Wildlife Service. (2023). Download seamless wetlands data by state. National Wetlands Inventory website. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. Accessed April 24, 2024. [https://www.fws.gov/program/national-wetlands-inventory/download-state-wetlands-data].

U.S. Department of Interior, Geological Survey. (2006). A Gap analysis of Hawai’i: February 2006 final report. National gap analysis program. [https://catalog.lib.uchicago.edu/vufind/Record/6329681/Details].

U.S. Department of Interior, Geological Survey. (2019). National Hydrography Dataset (NHD) – USGS national map downloadable data collection: USGS – National Geospatial Technical Operations Center (NGTOC). [https://www.usgs.gov/national-hydrography/access-national-hydrography-products].

Wagner, W.L., D.R. Herbst, & S.H. Sohmer. (1999). Manual of the flowering plants of Hawai’i, Revised Edition. Bishop Museum Press, Honolulu.

Western Regional Climate Center, (2020). Climate of Hawai’i. Available: [https://wrcc.dri.edu/Climate/narrative_hi.php].

Wood, K.R. (1998). Personal observations and checklist of the vascular plants of upper Mapulehu Valley, Molokai (East Side/2,400-3,000 Feet Elevation). National Tropical Botanical Garden Biological Report. Technical Report - March 1998.

DEFINITIONS
These definitions have been greatly simplified for brevity and do not cover every aspect of each topic.

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 buffelgrass. The terms aridic and torric are basically the same.

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 and duration 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.

Isohyperthermic soil temperature regime: A regime in which mean annual soil temperature is 72 degrees F (22 degrees C) or higher and mean summer and mean winter soil temperatures differ by less than 11 degrees F (6 degrees C) at a specified depth.

Isomesic soil temperature regime: A regime in which mean annual soil temperature is 47 degrees F (8 degrees C) or higher but lower than 59 degrees F (15 degrees C) and mean summer and mean winter soil temperatures differ by less than 11 degrees F (6 degrees C) at a specified depth.

Isothermic soil temperature regime: A regime in which mean annual soil temperature is 59 degrees F (15 degrees C) or higher but lower than 72 degrees F (22 degrees C) and mean summer and mean winter soil temperatures differ by less than 11 degrees F (6 degrees C) at a specified depth.

Major Land Resource Area (MLRA): A geographic area defined by NRCS that is characterized by a particular pattern of soils, climate, water resources, and land uses. The island of Hawaii contains nine MLRAs, some of which also occur on other islands in the state.

Naturalized plant community: A community dominated by adapted, introduced species. It is a relatively stable community resulting from secondary succession after disturbance. Most grasslands in Hawaii are in this category.

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 PhD
John Proctor
Carolyn Auweloa
Kendra Moseley
Amy Koch
Ann Tan
Jennifer Fedenko
Sarah Quistberg
Daniel Bowman
Brenden Brazee

Approval

Kendra Moseley, 5/08/2025

Acknowledgments

Assistance, advice, review, and/or insights:

Mick Castillo
Michael Constantinides, NRCS-PIA
Susan Cordell, USFS
Gordon Cran, Kapapala Ranch
David Foster, volunteer
JB Friday, UH Forestry Extension
Rick Gordon
Basil Hansen, The Nature Conservancy
Flint Hughes, USFS
Chris Jasper, NRCS Soil Survey
Mel Johansen, The Nature Conservancy
Kathy Kawakami, US Army Pohakuloa Training Ground
Rhonda Loh, Volcanoes National Park
Kamehameha Schools/Bishop Estate
Miles Nakahara, Hawaii DOFAW
Laura Nelson, The Nature Conservancy and NRCS
Patrick Niemeyer, NRCS Soil Survey
Billy Paris, rancher
John Pipan
Jon Price, USGS
John Replogle, The Nature Conservancy
Paul Scowcroft, USFS
Earl Spence, grazing consultant
Jim Thain
Mike Tomich
Quentin Tomich
Tim Tunison, Volcanoes National Park
Jill Wagner, consultant, Future Forests
Rick Warschauer

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	05/13/2025
Approved by	Kendra Moseley
Approval date
Composition (Indicators 10 and 12) based on	Annual Production