Assessment of future agricultural land potential using GIS and regional climate projections for Hawaiʻi island: an application to macadamia nut and coffee

Abstract

A major component of sustainable resource management involves working within the limitations of a particular ecosystem. Spatially matching crop ecological ranges with the limiting factors of the natural environment can provide base-line information with which to evaluate site suitability. Suitable crop locations are particularly relevant in Hawaiʻi where large differences in environmental factors occur over relatively short distances. This study utilized expert-based knowledge of coffee and macadamia ecological ranges and regional climate projections to evaluate the likely impacts of climate change on crop production. Environmental datasets (e.g. rainfall, temperature, soil properties) for the Island of Hawaiʻi were compared to the ecological ranges of coffee and macadamia crops using geographic information systems (GIS) based suitability analysis. Fuzzy sets were utilized to numerically rate the level of compatibility between the environmental data and the crop requirements for a given site. Future environmental conditions were projected using a downscaled regional climate change model for the Hawaiian Islands. Future rainfall and temperature projections support continued coffee production in the major coffee producing areas on Hawaiʻi Island while locations currently cultivating macadamia are predicted to encounter declines in future production due to above optimal temperatures at low elevation farms and above optimal rainfall at upper elevation farms, particularly on the windward side of the Island. Continued coffee and macadamia production on Hawaiʻi Island would require community specific strategies as each farming community would encounter different challenges and opportunities in crop production related to the current and future distribution of rainfall and temperature.