Rapid ʻŌhiʻa Death (ROD) is a new fungal disease caused by two distinct species, Ceratocystis lukuohia and C. huliohia, that attack and kill ʻōhi‘a (Metrosideros polymorpha), the most abundant native tree and important keystone species in the state of Hawai‘i. U.S. Army Garrison Pōhakuloa Training Area (PTA) contains approximately five percent of the total ʻōhi‘a forests on Hawai‘i Island. Because ROD continues to threaten ʻōhi‘a forests on Hawaiʻi Island, the PTA Natural Resources Program (NRP) monitors for symptomatic trees on the installation and collects samples to be tested when infection is suspected.
The NRP partners with the Big Island Invasive Species Committee (BIISC) to conduct annual helicopter surveys of ʻōhi‘a forests on PTA as part of island-wide and state-wide ROD surveys. This operation contributes to an interagency initiative to document the distribution of ROD infected areas statewide as part of an early detection and rapid response program. The objective is to map and monitor ROD impacted areas, and track disease movement.
Follow-up ground surveys to verify ROD presence are done by NRP staff if aerial surveys identify ROD suspect trees. This work informs the Army if further precautions need to be in place to prevent the spread of ROD to other areas, especially other islands, by military personnel, vehicles, and gear.
NRP staff Pamela Sullivan and Jason Dzurisin with the Center for Environmental Management of Military Lands (CEMML) at Colorado State University, and Dustin Swan, Forest Response Coordinator with BIISC, conducted annual aerial ROD surveys at PTA on January 20, 2023. Fortunately, they did not identify any ROD suspect trees at PTA and Dustin Swan commented that the ʻōhi‘a forests at PTA looked healthy compared to many other ʻōhi‘a forests on the island.
PTA has several characteristics that may help prevent or slow the establishment of ROD at the installation including large ungulate-free fenced areas, a high-elevation, and dry conditions. There are 15 conservation fence units totaling 86 miles in length that protect approximately 37,300 acres of native habitat at PTA. As of 2017, all of the fence units are considered to be ungulate-free.
Data from recent and ongoing research indicate that dry forests, higher elevation areas, and those lacking nonnative ungulates (which may spread the fungus) all seem to have lower incidents of ROD infection compared to wet, lower-elevation forests and those with ungulates present.
“Land stewardship is a huge part of U.S. Army Garrison Pōhakuloa Training Area’s mission, and we have a dedicated team of nearly 30 natural resources professionals,” said Lt. Col. Kevin Cronin, PTA commander. “We have 86 miles of fencing to protect endangered, threatened and native species; have an active hunting program to reduce the ungulate population; a greenhouse to propagate native species, just to name a few of the things we do in the environmental stewardship space.”