UH Anthropologist Examines Deforestation Across the Pacific

Implications for the survival or collapse of certain Pacific Islands societies published in Nature

Why were some Pacific islands deforested before Western contact while others retained native or introduced tree growth? And what does the answer say about the rest of the world?

Writing in a recent issue of the journal Nature, University of Hawaiʻi at Mānoa anthropologist Barry Rolett and UCLA geographer Jared Diamond identify nine environmental factors that predispose toward deforestation and reforestation. Their model not only predicts as most vulnerable three islands that were completely deforested—Necker, Nihoa and Easter Islands—but it also may be useful in explaining why the Fertile Crescent and Mayan society collapsed while Japan and highland New Guinea thrived.

The pair, whose collaboration started after Diamond visited Hawaiʻi as part of UH Mānoa‘s Distinguished Lecture Series in 2000, coded Pacific islands for the amount of deforestation and forest replacement based on the observations of early European visitors. They used four types of statistical analysis to weigh nine variables. Predisposing islands to deforestation are:

· low rainfall, which slows plant growth and increases risk from fire;

· higher latitudes, where cooler temperatures slow plant growth;

· age, because soil nutrients are lost over time;

· distance from fallout that replenish soil nutrients—volcanoes that generate ash fallout and Central Asia, which contributes to atmospheric dust;

· low elevation—mountains rains provide water and capture atmospheric dust, and streams carry nutrients to the lowlands;

· small and isolated—limiting diversity of tree species and inaccessible areas and reducing trading and raiding as options for obtaining resources.

While they don‘t dismiss the impact of Polynesian societal practices on deforestation, Rolett and Diamond conclude that Easter Island‘s collapse had less to do with improvident actions than the fragile environment. They hope to see their analysis further refined and extended to other societies and locations.