There are 18 surviving Serianthes nelsonii trees in the Guam National Wildlife Refuge at Ritidian that have been planted, cared for and monitored over the last few years through a combination of local, federal and military efforts, plant and wildlife experts said Monday.
And while the group of scientists and conservationists that are part of saving this endangered tree from extinction on Guam have wanted to plant the tree outside of the refuge at Ritidian, a lack of local preservation sites has made that option not feasible.
The rare tree, also called fire tree, hayun lagu, or northern tree, has become one of the talking points for certain senators calling for a pause on the construction of the Live-Fire Training Range Complex, which is part of the facilities for the relocation of almost 5,000 Marines from Okinawa to Guam. The governor, at the urging of the local senators, said Friday she would ask the military to pause construction around the rare tree on Northwest Field within Andersen Air Force Base.
The governor also said Friday a DNA study has been requested to determine whether the tree is in fact a Serianthes nelsonii and learn whether "it can reproduce." The rare tree within the Air Force Base fence has been called the last mature tree of that species on Guam.
A majority of local senators have signed a resolution calling for a pause to the construction of the Live-Fire Training Range Complex on Guam. Speaker Tina Muña Barnes on Monday said the resolution raises two key issues: the protection of historical sites, as and the rare tree.
"Calling for a temporary pause in the buildup, does not mean I am anti-military, it just means that as a government, we have to continue to do our due diligence. We need to quickly regroup, fully understand the impact, as well as the responsibilities, duties, and obligations of our government of Guam," Barnes stated.
Protected for years
James McConnell, a professor of ornamental horticulture at the University of Guam College of Natural and Applied Sciences, said the mature tree that has been the focus of much attention these last few weeks has been mature since the 1960s or 1970s, and has been protected through a variety of efforts, primarily by the Department of Defense.
However, it has some heart rot, McConnell said.
Heart rot is defined as a fungal disease that causes the decay of wood at the center of the trunk and branches. Fungi enter the tree through wounds in the bark and decay the heartwood.
He said the tree is "getting weaker and weaker" and the concern is whether it could withstand the next major storm.
In 2017, the U.S. Guam National Wildlife Refuge received funding from a cooperative recovery initiative through the U.S. Fish and Wildlife Service to keep the Serianthes nelsonii from going extinct on Guam.
"It involved propagating, outplanting and monitoring the trees on the refuge itself," said Tammy Summers, manager for the local refuge site.
Summers noted that the effort to save endangered trees and fauna endemic to Guam has continued over the years with the help of various people from different educational, environmental, military and local government agencies.
"With the help of the Guam Plant Extinction Prevention Program, they planted 73 trees. Unfortunately, only 18 remain alive at this time," she said. "We lost some trees in 2017 to insect damage, primarily the infestation of the roots by the mealy bugs, a collapse syndrome of an unknown cause. (And) the ones that died in 2018, we lost to damage from feral pigs and deer. It's been a real fight between the insects, and feral pigs and deer."
No local preservation areas
McConnell said as part of the effort to save the serianthes nelsonii here on Guam, they planted the seedlings at Ritidian, which was the only real option.
"One of the problems is that GovGuam has never established protected areas. And even though their forestry department has identified key areas in the island, it's never been officially deeded," McConnell said. "If we plant this listed species, we don't want it to be in an area that's going to be developed. That's one of the things I want to point out ... that we're limited in planting outside of (the military) base."
McConnell said Ritidian isn't the only area where serianthes nelsonii has previously grown and flourished. A few decades ago, there were several others in central and southern Guam as well, including Tarzan Falls and other limestone areas.
"Over time those trees declined," he said, adding that the one mature tree in Ritidian has escaped whatever is causing the decline in other areas throughout the island, but its longevity is not necessarily because Ritidian is a "preferred habitat" for the species.
McConnell said the Department of Defense has been supporting the effort to save and propagate the protected tree "for a good many years. I, only more recently, have had the grant to oversee the project."
He said help is needed, however, because the trees need long-term maintenance.
McConnell said he and a team of scientists did start a genetic study to look at the trees in Rota and Guam, to see if they could use the Rota trees to help revitalize the population here.
The same species of Serianthes nelsonii is thriving in Rota and their seedlings are "vigorous." He said part of their study is to determine whether it is OK to mix the two without "losing" the specific genetic information of the tree found here.
"I don't know what the big issue is about the DNA study. It's the same species as the one at Rota," McConnell said. "Having genetic variation doesn't mean anything unique. It's the same species. All the remaining plants have some difference in the genetics, just like all plants and animals. ... The genetic variation is what you'd find in a normal population of any species."
He said Fish & Wildlife is funding one student's efforts to study the genetics of the tree. The student is working on the project as part of her doctoral study, which may be completed in December.