Inter-Island production variability and Pre-Contact carrying capacity estimates: A geospatial analysis of taro farming in Rurutu, (Austral Islands, French Polynesia)

Abstract

Our study explores pre-contact taro cultivation in pondfield irrigation systems on Rurutu (Austral Islands, French Polynesia). Understanding the size and extent of these systems is critical for estimating pre-contact human population, the ability to produce surplus, and socio-political dynamics. Since peak taro cultivation occurred across Polynesia prior to its historic documentation, the extent of wetland cultivation must be estimated from other sources. We explore pre-contact ecology and population levels on Rurutu using Landsat imagery and geospatial suitability analysis to estimate the maximum extent of the island’s pondfield irrigation systems. A primary goal was to develop an intra-island comparison of probable annual yields of taro to model pre-contact population sizes and their distribution at the system and socio-political district scales. Our model indicates the likely presence of 20 dormant taro systems on Rurutu. Our results point to significant intra-island differences of taro production on the island in the pre-contact era. We suggest that Rurutu’s Open socio-political structure was maintained, in part, by unequally dispersed arable taro land throughout the island which contributed to intra-island differences in annual yields and population densities resulting in endemic pre-contact warfare. We end by linking our data to ongoing conversations regarding resilience in Oceania and beyond.