Physiographic features

This ecological site occurs on tidal flats on coastal plains (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 20 to 46 inches (508 to 1,168 millimeters) while actual (10th and 90th percentiles) values for annual average precipitation range from 19 to 65 inches (483 to 1,651 millimeters). Extreme values range from 18 to 91 inches (457 to 2,311 millimeters). The mean annual precipitation is 36 inches (914 millimeters) and the median annual average precipitation is 31 inches (787 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 75 to 77 degrees F (24 to 25 degrees C) while actual (10th and 90th percentiles) values for annual temperatures range from 75 to 81 degrees F (24 to 27 degrees C). Extreme values range from 73 to 82 degrees F (23 to 28 degrees C). The mean annual temperature is 77 degrees F (25 degrees C) and the median annual temperature is 75 degrees F (24 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 low and 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 "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 (1,850 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). These major storms occur most frequently between October and March. 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).

Table 4. Representative climatic features

Climate stations used

• (1) WAIMEA 947 [USC00519629], Kekaha, HI

• (2) BARKING SANDS [USW00022501], Kekaha, HI

• (3) WAIKIKI 717.2 [USC00519397], Honolulu, HI

• (4) KII-KAHUKU 911 [USC00514500], Kahuku, HI

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

Influencing water features

This ecological site is associated with areas of permanent open water. Some open water is due to sites being diked or impounded. Only two soil components, Kaloko noncalcareous variant and Keeau, extend to tidal, saltwater, estuarine areas. Most sites are described in the National Wetland Inventory (NWI) as palustrine (small, shallow, non-saline, without wave-formed or bedrock shorelines). Kaloko and Keeau clay range from palustrine to estuarine (USFWS, 2023).

Number of National Wetland Inventory (NWI) features overlapping ecological site: freshwater emergent wetlands (541), freshwater pond (196), riverine (126), freshwater forested/shrub wetland (80), estuarine and marine wetland (62), and estuarine and marine deepwater (26) (USFWS, 2023).

Number of National Hydrologic Dataset (NHD) features overlapping ecological site: lake/pond (54), reservoir (16), stream/river (16), swamp/marsh (16), sea/ocean (2), and foreshore (1) (USGS, 2019).

Soil features

The soil components associated with this ecological site are Kaloko, Kaloko drained variant, Kaloko noncalcareous variant, Keaau, Mokuleia poorly drained variant, Nohili, and Pearl Harbor.

Most of the soils in this ecological site are Endoaquolls. These are soils with a dark surface horizon high in organic matter and base cations, an aquic soil moisture regime (in which the soil is free of dissolved oxygen because it is saturated by water), and a regional water table that is at or near the soil surface for extended periods. Most of the soils have a year-round warm soil temperature regime (isohyperthermic). All are moderately deep to very deep and poorly or very poorly drained. They formed in alluvium over calcareous materials (marl, coral sand, or limestone), except for two soils noted below. Surface horizons from 0 to 10 inches (0 to 254 millimeters) have pH values ranging from 6.7 to 7.9 while pH values from 10 to 20 inches (254 to 508 millimeters) range from 6.7 to 8.5 (USDA-SCS, 1972).

Mokuleia is an Aquic Haplustolls. Aquic Haplustolls are mainly in depressions or on flood plains (USDA-SCS, 1972).

While water table depths typically range from 18 to 48 inches (46 to 122 centimeters), two are greater than 72 inches (183 centimeters). Some soils have deeper permanent water tables indicated by gleyed conditions. The high pH of some of these soils may hinder development of hydric indicators (USDA-SCS, 1972).

Kaloko noncalcareous variant soils developed in alluvium over noncalcareous material, unlike the other phases of this soil series. It is sometimes ponded on the surface (details not in Soil Survey) and is gleyed from the surface to the bottom of the soil profile, indicating persistent saturation and anaerobic conditions (USDA-SCS, 1972).

Pearl Harbor soils developed in alluvium deposited over, and mixed with, muck or peat. It is classified as thapto-histic, meaning the soil profile contains a buried organic horizon within 40 inches (102 centimeters) of the mineral soil surface (USDA-SCS, 1972).

Many of the former wetlands have been drained and are used for homesites, urban development, pasture, or crops. This is particularly the case for Kaloko and Nohili on Kauai.

Adjoining the soils described above are areas mapped as Marsh; it is not mapped as a soil series but rather is called a Miscellaneous Area. By definition, they have little or no soil and support little or no vegetation. However, in the Soil Survey of Islands of Kauai, Oahu, Maui, Molokai, and Lanai, State of Hawaii upon which this ecological site is based, Miscellaneous Areas are extensive, and most and were mapped by low-intensity reconnaissance methods that provide less-detailed information than that presented for soil series and their phases. In many cases and especially this one, Miscellaneous Areas in Maui, Molokai, Lanai, Oahu, and Kauai are well-vegetated and/or contain plant and animal species of interest to conservationists (USDA-SCS, 1972). Marsh is described in the following paragraphs.

Complete soil information is not available for Marsh. They occur on Kauai and Oahu, where they often abut or intermingle with the soil series of this ecological site. They also occur on Molokai, on which this ecological site does not occur. Marsh soils are likely poorly drained soils consisting of a peat layer over mineral layers of coral rubble, shell fragments, or alluvial sand and silt. Soils may be periodically flooded. Ponding may occur in low areas after heavy rainfall or high tides; upon drying, salt crystals may accumulate on the surface to produce a bare, unvegetated spot.

Waters are brackish to fresh, depending on proximity to the ocean. Elevations are 0 to 40 feet (0 to 12 meters) above sea level. Annual air temperatures, wetness, and proximity to the ocean are associated with very warm (isohyperthermic), water-saturated and anaerobic (aquic), and, in places, elevated salinity conditions. Representative annual rainfall averages 20 to 46 inches (508 to 1,168 millimeters). Vegetation consists of a mix of sedges, grasses, forbs, and a species of fern. Many of the characteristic plant species are adapted to ranges of salinity, enabling them to occupy wide areas along the salinity gradient (USDA-SCS, 1972).

Table 5. Representative soil features

Table 6. Representative soil features (actual values)

Other references

REFERRENCES for R163XY005HI Aquic Coastal Wetland

Allen, J.A. (1998). Mangroves as alien species: the case of Hawaii. Global Ecology and Biogeography Letters 7:61-71.

Browning J.H., Reeves M., Amidon F., Stephen Miller, and Charrier J.C. (2019). Hawai'i: The Wetland System of Hawai'i. Elsevier Inc.

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

Elliott M.E. (1981). Wetlands and wetland vegetation of the Hawaiian Islands. M.Sc. thesis, University of Hawaii Manoa, Honolulu, HI. Quoted from Allen 1998.

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].

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.

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.
[https://doi.org/10.3389/fsufs.2023.1116929].

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

Rock, J.F. (1st edition 1913, reprinted 1974). The Indigenous trees of the Hawai’ian Islands. C. E. Tuttle Company, Rutland, V.T. & Tokyo, Japan.

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.

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

Aquic soil moisture regime: A regime in which the soil is free of dissolved oxygen because it is saturated by water. This regime typically exists in bogs or swamps.

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, wili wili, 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.

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.

Gleyed: A condition of soil from which iron has been reduced (in the redox chemistry sense) and removed during soil formation or that saturation with stagnant water has preserved a reduced state. If iron has been removed, the soil is the color of uncoated sand and silt particles. If iron is present in a reduced state, the soil is the color of reduced iron (typically bluish-gray). Redox concentrations (spots of oxidized iron, formerly called mottles are often present.

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.

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.

Mollisols: Soils with relatively thick, dark surface horizons, high cation-exchange capacity, high calcium content, that do not become hard or very hard when dry. Mollisols are conducive to plant growth. They characteristically form under grass in climates that are seasonally dry, but can form under forests.

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 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.

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.

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
Daniel Bowman
Ann Tan
Jennifer Fedenko
Sarah Quistberg

Approval

Kendra Moseley, 5/08/2025

Acknowledgments

Assistance, advice, review, and/or insights:

Mike Kolman, NRCS
Jennifer Higashino, NRCS
Mathew Cocking, NRCS
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
Matthew Cocking, 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