Kahikinui (Maui Island)

This area encompasses the ancient political district (moku) of Kahikinui, on the southern slope of Haleakala volcano, rising from sea level to 3,000 m asl, a magnificent altitudinal gradient cross-cut by substrates of varied geological age (Figure). Kahikinui typifies a leeward climatic zone with pronounced seasonality ("kona" rains predominate) and a total annual precipitation of 250-1000 mm, which puts it on the margin for dryland cultivation of Polynesian crop plants, especially in drought periods. The vegetation of this leeward slope has long been noted as a prime example of the high taxonomic diversity characteristic of Hawaiian dryland forests. The eastern half of the district has older substrates of the Kula Volcanic Series (400 kyr) with deeply weathered soil profiles and considerable hydrologic incision. In stark contrast, the western part of the district consists of young lava flows of the Hana Volcanic Series (0-60 kyr), a rejuvenation phase of Haleakala, resulting in rugged, unweathered or barely weathered surfaces lacking significant stream incision. A further resource restriction in Kahikinui was imposed by the coastal geomorphology, largely one of low sea cliffs and an absence of coral reefs, hence relatively low biotic diversity and biomass, rendering marine protein exploitation marginal.
Since 1994, Kahikinui has been archaeologically investigated by three coordinated teams of archaeologists from U. C. Berkeley, Northern Illinois University, and the State of Hawai'i. Two adjacent ahupua'a territories, Kipapa and Nakaohu, comprising an area of 8 sq km in central Kahikinui, have been intensively surveyed from the coast up to 1200 m above sea level where site density becomes very sparse. The resulting GIS database includes some 1,789 archaeological features.
Additionally, Kirch and his team have conducted extensive excavations in a series of habitation, agricultural, and ritual sites that have provided the basis for writing a detailed, local-level history of land use, local environmental modifications, resource use, micro-demographic distributions, group organization and interactions, and iconic (ritual) marking of the landscape with monumental architecture. A suite of more than 120 14C age determinations, now being augmented by U/Th dating of coral offerings from ritual sites, anchors this cultural history firmly in time, at a resolution of ± 75 yr. Frequency distributions of dated habitation sites furthermore provide the basis for a proxy estimate of the rate of population growth beginning with initial human incursion into the region, up to abandonment ca. A.D. 1870.
Using multiple lines of evidence including zooarchaeological faunal materials, charcoal, opal phytoliths, and other plant microfossils, pulmonate gastropods, and other sources, we have begun to develop a temporally and spatially fine-grained reconstruction of biotic resources and their distributions over the period of Polynesian occupation. In particular, our most recent research has focused on hydrological changes in our study area resulting from deforestation in an upland belt of cloud forest located above the main zone of archaeological settlement.

Kohala (Hawai'i Island)

Kohala has been the focus of extensive--and to date independent--archaeological, pedological, ecosystem, and paleoecological studies (Figure). The area encompasses the oldest volcano on the Island of Hawai'i, with an edifice that formed by 400 kyr ago (Pololu series) and substantial areas that were covered by post-shield eruptions about 150 kyr ago (Hawi series). The volcano's wet windward slope is divided by deeply incised valleys, the largest of which (Waipio Valley) was the major locus of irrigated taro agriculture and (probably not coincidentally) an important seat of the paramount chiefs of the island. The undissected leeward slope supports one of the most spectacular rainfall gradients on Earth, reaching from <200 mm to >3500 mm annual precipitation in a distance of 15 km.
Research by Chadwick and colleagues has demonstrated that continuous variation in rainfall on this gradient has led to some striking discontinuities in soil properties (Kelly et al. 1998, Chadwick and Chorover, in press). In particular, soil acidity is low and cation availability is consistently high as rainfall increases from <200 to 1400 mm/yr. Above that point, acidity increases and cations decrease sharply. Soil cations are derived almost entirely from basalt weathering below 1400 mm/yr rainfall, and from marine aerosol above that level. While the potential for basalt weathering increases linearly as a function of rainfall, at this soil age all of the primary minerals have been depleted from sites receiving >1400 mm rainfall. This sharp transition occurs at higher rainfall in sites younger than 160 kyr and at lower rainfall in older sites.
Leeward Kohala also supported one of the most extensive dryland farming systems in the archipelago, covering roughly 19 km by 4 km (~55 km2). The Kohala field system is characterized by a reticulate grid of stacked-stone field boundaries (see Figure 2); it incorporates thousands of smaller free-standing stone architectural features, including habitation sites and ritual structures. Archaeological research has traced the temporal development of both the field system and associated coastal and inland residential patterns, beginning as early as 1000 A.D. and continuing into the first decades after European contact. Later research focused on the windward valleys and their irrigation systems. Most recently, Graves and Ladefoged have applied a GIS approach to model the spatio-temporal development of the leeward field system. Cropping-cycle intensification occurred during the period A.D. 1300-1800; it was focused on areas receiving from about 800 to 1500 mm of annual precipitation.

Halawa Valley (Moloka‘i Island)

Halawa Valley is the easternmost of four large amphitheater-headed valleys on Moloka‘i Island (Figure); it typifies a wet valley on an older island, with large-scale pondfield irrigation. Rainfall in excess of 3000 mm/yr in the drainage basin supports a permanent stream with an average flow of 19.7 million gallons per day, providing the basis for extensive irrigated cultivation of taro in precontact and historic times. The main valley is roughly 3 km long and ranges from 0.5-1 km wide, with broad, colluvial slopes and an alluvial floodplain at the stream mouth. This topography was amenable both to the construction of irrigated fields on the floodplain and lower slopes, and to extensive habitation and dryland farming on the higher colluvial slopes. In the early to mid 19th century, Halawa was noted for its taro irrigation complexes, supporting a population of around 500 persons in 1836 (Kirch and Kelly, 1975).