Modelling the potential distribution of endangered, endemic Hibiscus brackenridgei on Oahu to assess the impacts of climate change and prioritize conservation efforts.

Abstract

In the Hawaiian dry forest, 45% of all tropical dry forest trees and shrubs are on the federal threatened and endangered species list. Research is needed to understand the current range of these endangered species, the factors that affect their current and future distributions, and ultimately, identify areas where the most successful restoration can be undertaken. This research uses species distribution modelling to predict the potential range of Hibiscus brackenridgei, the state flower of Hawaii and a federally endangered species found on Oahu. We used presence data and the modelling algorithm Maxent to model the current potential distribution of H. brackenridgei, identify climate and environmental variables that influence the species’ distribution, and model the species’ predicted future distribution based on a range of projected climate change scenarios. Statistical analysis suggests that the Maxent models accurately predict the species’ distribution, and therefore, may be useful for conservation management. Comparing the current model with the future models of changes for 2060-2089, changes in the potential niche of H. brackenridgei only range by -4% to 14%. This suggests that the predicted changes in climate, under both low (B2a) and high (A2a) SRES (Special Report on Emissions Scenarios) global emissions scenarios, may not significantly impact the future distribution of H. brackenridgei on Oahu. We identified a total of 115 km2 of very highly (≥ 0.70) and highly (≥ 0.50) suitable habitat which represents potential areas where restoration projects could be implemented. This research suggests that threats like habitat loss, fire, invasive species, and grazing may be more important than climate for the future conservation of Hawaiian dry forest species.