Presented by Pamela Sullivan at the National Military Fish and Wildlife Association’s 2019 annual meeting and training workshop. Naturally occurring and human induced wildland fires on military installations present serious risks to not only people, infrastructure, and training areas, but also valuable natural resources. The incidence of wildfires at Pohkuloa Training Area (PTA) on Hawaii Island is high due to the volume of munitions fired downrange and the number of pyrotechnics used in training.
Hawaiian ecosystems are not typically adapted to fire. Due to a combination of poorly adapted native species and the introduction of highly invasive pyrophytic species over the past century or more, wildfire has altered and degraded native Hawaiian ecosystems. For example, invasion of non-native grasses changes the fire regime, altering the ecosystem to promote more frequent fires. The non-native grasses are much better adapted to fire and thrive in fire disturbed ecosystems, exacerbating the grass-fire cycle. The most problematic fuels issue at PTA is the continued invasion and expansion across the installation of fountain grass (Cenchrus setaceus), a highly invasive, non-native, drought tolerant grass. Thus, it’s critical to protect sensitive ecosystems harboring federally listed species that are located in grass-invaded, fire prone areas at PTA. Given the high incidence of wildfires at PTA and conditions conducive to fire spread (e.g., dry, windy, flashy fuels), wildfires pose a significant risk to most of the 26 federally listed species, including 20 plants and 6 animals, that are present on the installation.
Fuels management within a network of fuel breaks that compartmentalizes the western side of PTA, in conjunction with weed control buffers (WCBs), can reduce potential fire spread, large fire probability, and ignition probability, thereby reducing or preventing impacts to listed species. Post-fire assessments of 2 wildfire events in endangered plant habitat at PTA indicate that pre-suppression of fuels in strategic locations reduced wildfire impacts to federally listed plant species. Results show that several WCBs around individuals of listed plant species, within which invasive grasses were removed, were effective in preventing fire from impacting the listed plants, while fuel breaks were effective in preventing fire spread into other listed species’ habitat, either as a resource for firefighters or as a physical barrier by themselves. In one 30 acre site, the only known location of the endangered Tetramolopium arenarium, the WCB likely prevented the extinction of that species as the fire burned right up to and around the WCB edge before stopping.