Dryland Agricultural Expansion and Intensification in Kohala, Hawai'i Island
Ladefoged, Thegn N., Graves, Michael W., Jennings, Richard P., Antiquity
Throughout the Hawaiian archipelago, dryland agricultural field systems constituted a significant component of the late prehistoric subsistence economy. Of the various dryland systems, the leeward or west side of the island of Hawai'i is notable for the three large systems of Kohala, Kona, and Waimea-Lalamilo [ILLUSTRATION FOR FIGURE 1 OMITTED]. The Kohala and Kona areas were archaeologically documented during the late 1960s and early 1970s by the University of Hawai'i and the Bishop Museum of Honolulu (Barrera 1971; Bevacqua 1972; Ching 1971; Crozier 1971; Newman 1970; 1972; Pearson 1968; Rosendahl 1972a; 1972b; 1994; Soehren & Newman 1968; Tuggle & Griffin 1973; see also Kelly 1983; Schilt 1984). The Waimea-Lalamilo field system was surveyed and tested in the 1970s and 1980s during a contract archaeology project undertaken by the Bishop Museum of Honolulu (Clark 1981; 1986; 1987; Clark & Kirch 1983). These studies have suggested that the field systems produced large quantities of food to support local farmers and residents as well as local and district-level chiefly elites. It is generally thought that the dryland agricultural systems had spread to their maximum extent, nearly reaching the edge of productive lands. And it is presumed that these systems had approached the limits of intensification, with smaller and smaller gains in agricultural production relative to new labour inputs. The focus of this paper is to evaluate these hypotheses in relation to the Kohala field system using a geographic information system (GIS) to analyse the spatial role of environmental variables on agricultural development. We also consider whether social processes are implicated in the extent and intensity to which dryland agricultural production was developed in Hawai'i.
The Kohala field system
The 19x4-km Kohala field system is situated on the leeward-facing and drier slopes of the Kohala mountains on the northwestern portion of Hawai'i Island [ILLUSTRATION FOR FIGURE 2 OMITTED]. The archaeological features associated with the system include many rock and earthen walls and alignments, terraced garden areas, planting and clearing mounds, enclosures, religious features, trails, as well as temporary and permanent residential features (Kirch 1985; 1994; Newman 1970; Rosendahl 1972; 1994). Sweet potato (Ipomoea batatas) was apparently the main cultigen of the field system, with other plants - dryland taro (Colocasia esculenta), yams (Dioscorea spp.), bananas (Musa hybrids), sugarcane (Saccharum officinarum), breadfruit (Artocarpus altilis), paper mulberry (Broussonetia papyrifera - on the field edges or at upper elevations (Newman 1970: 119; Rosendahl 1994: 63-4). The long axes of fields throughout the Kohala system were oriented parallel to the elevational contours, and the walls would have functioned as windbreaks from the trade winds which sweep down the slopes of the Kohala mountains (Newman 1970: 28, 143). Configured in this way, the walls would have reduced evapotranspiration and - with heavy mulching - retained essential moisture for the crops (Smith & Schilt 1973: 314). This alignment of fields also conserved water by retaining and dispersing surface run-off, and inhibited wind erosion and soil creep (Rosendahl 1994: 35).
Models for intensification at Kohala
Field systems such as those at Kohala are the remnants of former agricultural practices and processes. Throughout Polynesia, but especially in Hawai'i, anthropologists have attempted to identify and reconstruct the development of traditional and prehistoric agriculture (Barrau 1961; Earle 1978; 1980; Handy 1940; Handy & Handy 1972; Sahlins 1958; Yen 1971; 1973; Yen et al. 1972). Agricultural change in prehistoric Hawai'i is generally viewed as the outcome of adaptation, expansion and intensification (Kirch 1985: 216; Tuggle & Tomonari-Tuggle 1980): adaptation is the process whereby cultigens and cultivation practices are introduced and adjusted to local conditions; expansion involves increasing the area covered by an established agricultural complex; intensification refers to increased inputs in order to achieve increased agricultural output (Kirch 1994: 19). …