New UH study finds link between rapid ohia death and feral pigs

HONOLULU (HawaiiNewsNow) - Hawaii Island is covered with acres of healthy ohia trees. But hundreds of thousands of trees have been killed by a fungus Ryan Perroy is following very closely.

“Basically, almost every part of Hawaii Island now has been impacted by this,” he said.

The University of Hawaii at Hilo associate professor was part of a research team that used cameras mounted on helicopters and drones to study how quickly rapid ohia death has spread over the past few years.

They found a link to feral pigs and other hooved animals.

“There is a significant difference in the amount of ohia mortality we see in areas which have ungulates compared to areas without ungulates,” he said.

The team surveyed ohia forests in Hawaii Volcanoes National Park and Laupahoehoe Forest Reserve. One area that was fenced off at the start of the study was breached by wild pigs.

“Prior to the breach there was essentially zero cases of ohia mortality in that area, but after the breach we started to see mortality levels very, very high,” Perroy said.

Many of the dead trees had stripped bark and root damage caused by the ungulates.

“Any kind of openings that you get into those trees is now an entry way for the fungal pathogens to enter,” he said.

More research needs to be done to determine if the animals carry the fungus. There are similar patterns of ohia death on Kauai.

“These forests, we rely on them for all kinds of ecosystem services and they’re also incredibly important culturally,” Perroy said. “This information needs to go into the decision making process about how we best manage and care for our forests.”

He calls it another piece in the rapid ohia death puzzle. The study was published in the journal Forest.

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