Kahoolawe, Hawaii: Soil Survey in a Highly Anthropogenic Landscape.

The Island of Kahoolawe, Hawaii, presents significant challenges for soil survey and soil characterization activities. Kahoolawe, the smallest of the seven major Hawaiian Islands, is an example of a strongly influenced anthropogenic landscape. Although much of the original pedogenesis took place under a wetter moisture regime, the island is now located in the rain shadow of Haleakala volcano on the island of Maui and receives less than 625 mm (25 in) annual rainfall. Cattle and goats introduced in the late 1700's devastated native vegetation resulting in significant erosion throughout most of the island. The island was used by the US Navy for gunnery practice beginning in 1941 and continued to be used as a firing and bombing range under US Navy control from 1954-1994. Ongoing feral ungulate grazing coupled with military use has left virtually the entire island highly eroded with large areas of sparse or non-existent vegetation. An initial field soil survey of the island was conducted by USDA-NRCS personnel between 1992 and 1994 under contract with the US Navy. This survey followed standard protocols to all practical extent. Soil samples were taken and profiles described; however, activities were significantly limited by the presence of unexploded ordinance. In the past year, using laboratory data from limited samples and much improved imagery (Digital Globe) and elevation data (IFSAR), NRCS staff have developed spatial and tabular databases for Kahoolawe that meet present National Cooperative Soil Survey (NCSS) standards. This poster will describe the constraints to mapping and describing soils in this challenging environment, the characteristics of these highly disturbed soils, the differences between these soils and what are evaluated to be similar soils on neighboring islands, and the rationale we used to characterize the soils and to develop and populate the spatial and tabular databases. We will also discuss how information from this updated survey can continue to be used by the Kahoolawe Island Reserve Commission (KIRC), the non-profit group charged with managing the island, to inform restoration and other management activities.