Ecological Site Description Ecological Site Characteristics Site Identification

Ecological Site Characteristics

This ecological site occurs on lava flows on sloping mountainsides of shield volcanoes. Lava flows are `a`a (loose, cobbly) or pahoehoe (smooth, relatively unbroken). Overlying ash flows in some areas are very deep on top of the original lava flows.

Average annual precipitation ranges from 30 to 60 inches. On westward-facing slopes (South Kona and part of Kau), most of the precipitation falls from March through June, with May being the wettest month. On southeastward-facing slopes (part of Kau), most of the precipitation falls from November through March, with January being the wettest month. Average annual temperature ranges from 68 to 74 degrees F. The climate can be generally classified as dry ustic and tropical in nature.

There are no water features influencing this site.

Typical soils are of three types: highly decomposed plant materials, either moderately deep in `a`a or shallow over pahoehoe; very shallow to shallow medial silt loams and medial sandy loams formed in rapidly weathered volcanic ash deposited over pahoehoe; and moderately deep to deep silt loams and silty clay loams formed in rapidly weathered volcanic ash deposited over `a`a or pahoehoe. Soils in intact lama forests often have a distinctive brown organic surface layer. The soils are somewhat excessively to well drained. Available water capacity (AWC) in most soils ranges from 1 to 3 inches; some deep ash soils have available water capacity of 5 to 8 inches. AWC refers to the volume of water available to plants in the upper 40 inches of soil, including rocks, at field capacity. Permeability is rapid in soils but can be very slow in underlying pahoehoe. Runoff potential ranges from negligible in `a`a to very high over pahoehoe. Moist colors range from black and very dark brown to dark reddish brown and very dusky red. Soil reactions (pH) range from strongly acid to neutral in surface horizons and strongly acid to neutral in deeper subsurface layers. Extremes of pH (CaCl₂) range from a low of 4.1 in Fluvents (a localized soil) to a high of 7.5 (horizons of Noio, Punalu`u, and Waiaha series). Erosion potential is slight. Soil temperature regimes range from isohyperthermic to isothermic. Soil moisture regimes are ustic (in most years, dry for more than 90 cumulative days but less than 180 days).