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 Pohakuloa Training Area as part of island wide and statewide rapid ʻōhiʻa death surveys.
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 Pohakuloa Training Area Dec. 17.
Fortunately, they did not identify any rapid ʻōhiʻa death suspect trees at Pohakuloa Training Area and Dustin Swan commented that the ʻōhi‘a forests at Pohakuloa Training Area looked healthy compared to many other ʻōhi‘a forests on the island.
Pohakuloa 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.