PŌHAKULOA TRAINING AREA, Hawaii -- Wildland fires in Hawaiʻi present serious risks to people, homes, communities, and infrastructure, but also to valuable natural resources–particularly rare native species.
Like other areas in the nation, the incidence of wildfires in Hawaiʻi has increased several fold over the last century, and particularly in the last decades with the effects of climate change worsening the threat.
Additionally, the introduction of invasive grasses has changed the fire regime, altering the ecosystem to promote more frequent fires.
This issue is evident at Pōhakuloa Training Area where highly invasive, drought tolerant grasses such as fountain grass (Cenchrus setaceus) occur in areas that contain endangered species. Thus, it’s critical to protect sensitive ecosystems harboring endangered species located in grass-invaded, fire prone areas from wildland fire.
To that end, the Pōhakuloa Training Area Natural Resources Program implements and maintains approximately 40 miles of fuel breaks and firebreaks on the installation.
Fuel management within the fuel break network, combined with weed control buffers, can reduce fire spread, large fire probability, and ignition probability, thereby reducing or preventing impacts from wildland fires to endangered species and native habitat.
This was demonstrated in July 2021, when one of the largest fires recorded in Hawaii (>42,000 acres) occurred on the slopes of Mauna Kea and spread into the Keʻāmuku Maneuver Area unit of Pōhakuloa Training Area.
Keʻāmuku Maneuver Area is former ranchland and thus a degraded grass-invaded landscape; it also contains two puʻu that are among the last refugia for three critically endangered plant species (Isodendrion hosakae, Lipochaeta venosa, and Vigna o-wahuensis).
The event underscored the challenges in controlling and containing a large wildland fire in grass-invaded, dryland habitat. Weed control buffers around the endangered plants have helped to restore the native habitat and reduce competition from invasive weeds.
The fuel breaks encircling the two puʻu, created to protect the plants from fire, served as effective assets for firefighters to conduct operations. The fire burned more than 3,100 acres around and between the two puʻu, engulfing most of the grassy fuels surrounding them. The fuel breaks provided firefighters a stronghold to defend both puʻu, which remained intact, preventing fire impacts to the endangered plants.
Pōhakuloa Training Area's Natural Resources Program will continue to implement and maintain fuel breaks and weed control buffers in fire-prone areas as the Army anticipates an increased threat from wildland fires due to climate change and expansion of invasive grasses across the landscape.
This fire event underscores the importance and value in removing and controlling fine fuels like invasive grasses in sensitive habitat to ensure the Army remains in compliance with its regulatory obligations of promoting the continued existence of endangered species while sustaining military training at PTA.
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