Physiographic features

This ecological site occurs on lava flows, alluvial fans, and terraces on the sloping mountainsides of shield volcanoes. Lava flows are aa (loose, cobbly) or pahoehoe (smooth, relatively unbroken) (USDA-SCS, 1972).

Table 2. Representative physiographic features

Table 3. Representative physiographic features (actual ranges)

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 68 to 114 inches (1,727 to 2,896 millimeters) while actual (10th and 90th percentiles) values for annual average precipitation range from 60 to 137 inches (1,524 to 3,478 millimeters). Extreme values range from 36 to 247 inches (914 to 6,274 millimeters). The mean annual precipitation is 93 inches (2,362 millimeters) and the median annual average precipitation is 85 inches (2,159 millimeters).

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 70 to 75 degrees F (21 to 24 degrees C) while actual (10th and 90th percentiles) values for annual temperatures also range from 70 to 75 degrees F (21 to 24 degrees C). Extreme values range from 61 to 81 degrees F (16 to 27 degrees C). The mean annual temperature is 72 degrees F (22 degrees C) and the median annual temperature is also 72 degrees F (22 degrees C).

The data presented in the climate normals tables below are from the Western Region Climate Center (Western Regional Climate Center, 2020). The available climate station data are most representative of the moderate precipitation areas of this ecological site. I used these data because they provide a reasonable approximation of the University of Hawaii data presented above.

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 "so" - soil temperature regimes in which mean summer and winter temperatures differ by less than 6 degrees C (11 degrees F).

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).

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 (1,829 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 3,048 meters), which include Mauna Kea, Mauna Loa, and Haleakala, occur at elevations of 2,000 to 4,000 feet (610 to 1,219 meters). A temperature inversion that fluctuates between about 5,000 and 7,000 feet (1,524 to 2,134 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 (USDA-SCS, 1972; Western Regional Climate Center, 2020).

On Kauai and Lanai, where the mountains are all lower than 6,000 feet (1,829 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 (USDA-SCS, 1972).

Besides the trade winds discussed above, other rainfall sources on the Hawaiian Islands include: a) "Naulu storms" (Leopold, 1949) 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 b) 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, 2020).

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 (USDA-SCS, 1972; Western Regional Climate Center, 2020).

Table 4. Representative climatic features

Climate stations used

• (1) PRINCEVILLE RCH 1117 [USC00518165], Princeville, HI

• (2) WAIHEE 837.5 [USC00519281], Kaneohe, HI

• (3) KAILUA 446 [USC00512679], Haiku, HI

• (4) KANEOHE MAUKA 781 [USC00513113], Kaneohe, HI

Influencing water features

This ecological site is intersected by many small to medium size streams that have cut gulches into the landscape. The gulches contain plant species found in the ecological site (USFWS, 2023).

Number of National Wetland Inventory (NWI) features overlapping ecological site: Riverine (670), freshwater forested/shrub wetlands (271), freshwater emergent wetlands (218) freshwater ponds (92), estuarine and marine wetlands (24), estuarine and marine deepwater (15), and lakes (14) (USFWS, 2023).

Number of National Hydrologic Dataset (NHD) features overlapping ecological site: Lakes/ponds (102), reservoirs (10), streams/rivers (6), swamp/marsh (4), sea/ocean (3), and foreshore (1) (USGS, 2019).

Soil features

The soil components associated with this ecological site are Hihimanu, Halii, Hanamaulu, Kalapa, Kapaa, Lawai, Makapili, Pooku, Kailua, Makawao, Pauwela, Kaneohe, Lolehaa, Paumalu, Tantalus, Waikane, and Haiku.

Most of the soils correlated with this ecological site are highly weathered Oxisols and Ultisols. Less frequent soil orders in this ecological site include Andisols and Inceptisols. All of the soils are very deep and well drained. All the soils have mineralogy that gives them pH dependent ion retention characteristics, apart from Tantalus which has pH high enough to impart significant cation retention. Most the soils have low pH in a range that can solubilize aluminum to toxic levels unless counteracted by adequate organic matter content. Soil temperature regimes are very warm (isohyperthermic) or, in very few cases, at the warmer extreme of isothermic. Soil moisture regimes are udic (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) or at the moist extreme of ustic (in which moisture is limited but present at a time when conditions are suitable for plant growth). In general, the supply of plant nutrient cations is low, and phosphorus is in forms that are relatively unavailable to plants, so that recycling of nutrients from deeper levels to the surface by plants and storage of nutrients in surface and near-surface organic matter is crucial (USDA-SCS, 1972).

Table 5. Representative soil features

Table 6. Representative soil features (actual values)

Other references

REFERENCES for R167XY001HI Oxidic Dissected Lowland

Abrahamson, I.L. (2013). Fire regimes in Hawai’ian plant communities. Fire Effects
Information System [https://www.fs.usda.gov/database/feis/fire_regimes/Hawaii/all.html].

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].

Cuddihy, L.W., & C.P. Stone. (1990). Alteration of native Hawai’ian vegetation: Effects of humans, their activities and introductions. University of Hawaii Cooperative National Park Resources Study Unit.

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

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.

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].

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.

Leopold, L.B. (1949). The interaction of trade wind and sea breeze, Hawai’i. Journal of Meteorology 6: 312-320.

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].

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.

Alluvial: Materials or processes associated with transportation and/or deposition by running water.

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.

Hydrous: A “soil texture modifier” for volcanic ash soils having a water content at the crop wilting point of 100 percent or more; a soil that holds more water than “medial” or “ashy” soils.

Ion exchange capacity: The ability of soil materials such as clay or organic matter to retain ions (which may be plant nutrients) and to release those ions for uptake by roots.

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

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

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

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.

Oxisols: Soils characteristic of humid, tropical or subtropical regions that formed on land surfaces that have been stable for a long time. In Hawaii, they typically occur on islands or parts of islands that have been volcanically inactive for a long time. Oxisols are highly weathered, consist largely of quartz, kaolin clays, and aluminum oxides, and have low ion exchange capacity and loamy or clayey texture.

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.

Perudic soil moisture regime: A very wet regime found where precipitation exceeds evapotranspiration in all months of normal years. On the island of Hawaii, this regime is found on top of Kohala and on parts of the windward side of Mauna Kea.

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.

Phosphorus adsorption: The ability of soil materials to tightly retain phosphorous ions, which are a plant nutrient. Some volcanic ash soils retain phosphorus so strongly that it is partly unavailable to plants.

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 1,500 kPa (the crop wilting point) in the soil or in specific horizons during periods of the year.

Soil temperature regime: A defined class based on mean annual soil temperature and on differences between summer and winter temperatures at a specified depth.

Soil reaction: Numerical expression in pH units of the relative acidity or alkalinity or a soil.

State: One or more community phases and their soil properties that interact with the abiotic and biotic environment to produce persistent functional and structural attributes associated with a characteristic range of variability.

State-and-transition model: A method used to display information about relationships between vegetation, soil, animals, hydrology, disturbances, and management actions on an ecological site.

Transition: A term describing the biotic or abiotic variables or events that contribute to loss of state resilience and result in shifts between states.

Udic soil moisture regime: A regime in which the soil is not dry in any part for as long as 90 cumulative days in normal years, and so provides ample moisture for plants. In Hawaii it is associated with forests in which hapuu (tree ferns) are usually moderately to highly abundant.

Ultisols: Soils that have been intensively leached and weathered. They have a B horizon that has accumulated clay that has translocated there from higher horizons. They have moderate to low cation exchange capacity and low base saturation. The highest base saturation normally is in the few centimeters directly beneath the surface due to cycling of bases by plants.

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
Daniel Bowman
Jennifer Fedenko
Sarah Quistberg

Approval

Kendra Moseley, 5/08/2025

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
Mike Kolman, NRCS
Jennifer Higashino, NRCS
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