PŌHAKULOA TRAINING AREA, Hawaii -- Rapid ʻōhiʻa death 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.
Pōhakuloa Training Area contains approximately 5% of the total ʻōhi‘a forests on Hawai‘i Island. Because rapid ʻōhiʻa death continues to threaten ʻōhi‘a forests on Hawaii Island, Pōhakuloa Training Area’s Natural Resources Program monitors for symptomatic trees on the installation and collects samples to be tested when infection is suspected.
The Natural Resources Program partners with the Big Island Invasive Species Committee to conduct annual helicopter surveys of ʻōhi‘a forests on Pōhakuloa Training Area as part of island wide and statewide rapid ʻōhiʻa death surveys.
"PTA is proud of its 30 member environmental team and the work they do day-in and day-out to protect our environment,” said Lt. Col. Kevin Cronin, commander, Pōhakuloa Training Area. “A big part of our efforts is working with partners in our community, such as the Big Island Invasive Species Committee.”
This operation contributes to an interagency initiative to document the distribution of rapid ʻōhiʻa death infected areas statewide as part of an early detection and rapid response program. The objective is to map and monitor rapid ʻōhiʻa death impacted areas, and track disease movement.
Follow-up ground surveys to verify rapid ʻōhiʻa death presence are done by Natural Resources Program staff if aerial surveys identify rapid ʻōhiʻa death suspect trees.
This work informs the Army if further precautions need to be in place to prevent the spread of rapid ʻōhiʻa death to other areas, especially other islands, by military personnel, vehicles, and gear.
Natural Resources Program staff Pamela Sullivan and Jason Dzurisin and Dustin Swan, Forest Response Coordinator with Big Island Invasive Species Committee, conducted annual aerial rapid ʻōhiʻa death surveys at Pōhakuloa Training Area Dec. 17.
They did not identify any rapid ʻōhiʻa death suspect trees at Pōhakuloa Training Area and Dustin Swan commented that the ʻōhi‘a forests at Pōhakuloa Training Area looked healthy compared to many other ʻōhi‘a forests on the island.
“Fortunately, we haven't detected rapid ʻōhiʻa death at PTA, but we will remain vigilant in conjunction with our community partners,” said Cronin. “To this end, we continuously monitor the land here and in particular our nearly 40 miles of ungulate exclusion fences that protect approximately 40,000 acres of the land from ungulates."
Pōhakuloa Training Area has several characteristics that may help prevent or slow the establishment of rapid ʻōhiʻa death at the installation including large ungulate-free fenced areas, a high-elevation, and dry conditions.
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 rapid ʻōhiʻa death infection compared to wet, lower-elevation forests and those with ungulates present.