Invasive grasses change landscape structure and fire behaviour in Hawaii

QUESTIONS: How does potential fire behaviour differ in grass‐invaded non‐native forests vs open grasslands? How has land cover changed from 1950–2011 along two grassland/forest ecotones in Hawaii with repeated fires? LOCATION: Non‐native forest with invasive grass understory and invasive grassland (Megathyrsus maximus) ecosystems on Oahu, Hawaii, USA. METHODS: We quantified fuel load and moisture in non‐native forest and grassland (Megathyrsus maximus) plots (n = 6) at Makua Military Reservation and Schofield Barracks, and used these field data to model potential fire behaviour using the BehavePlus fire modelling program. Actual rate and extent of land‐cover change were quantified for both areas from 1950–2011 with historical aerial imagery. RESULTS: Live and dead fuel moisture content and fine fuel loads did not differ between forests and grasslands. However, mean surface fuel height was 31% lower in forests (72 cm) than grasslands (105 cm; P