Burn probability mapping of Moutohorā (Whale Island), Bay of Plenty, Aotearoa New Zealand

Abstract

: Aotearoa New Zealand’s conservation management has had a strong focus on offshore islands, though this investment is at risk from human-influenced factors such as biosecurity incursions and wildfire. During the last century several wildfires have occurred on Moutohorā (Whale Island), Bay of Plenty, which is a location for six threatened plant and three threatened animal species. Conservation and cultural management on Moutohorā over the last several decades has restored the island to become the most densely vegetated it has been since before humans arrived, albeit with a very different composition. The Prometheus fire-growth simulation model was used to produce a series of deterministic fire extent maps, which were compiled into seasonal burn probability maps. The average simulated fire extent was 53.2 ha, with a maximum area of 129.9 ha (or approx. 84% of the entire island), with 23% of fires not growing past 0.01 ha. Fires that start in summer, the western end of the island, and in mānuka and/or kānuka had the highest mean and maximum fire extent. Burn probability maps are a key step in quantifying the spatial fire risk for important conservation locations such as Moutohorā.