Even sturdy-looking tree could have hidden risks
By Jan TenBruggencate
Advertiser Science Writer
Property owners have a responsibility to make sure that large trees on their land don't pose a danger to themselves and neighbors, but tree experts say it's not always easy to tell which ones are at risk.
Unless, of course, the trees have a history of problems, like the century-old eucalyptus trees along Pi'iholo Road in Olinda, Maui. Pi'iholo resident Richard Rost said a neighbor's tree fell near his home, worrying him. He persuaded his neighbor to cut down other trees that might place his house at risk.
Trees along the roadway remain a problem, he said.
"My wife's car was hit by a falling branch. We had a neighbor whose car got hit. Just about everybody who has lived along that road for any length of time probably has a tree story," he said. And that's on top of the inconvenience of fallen trees blocking traffic and knocking out electrical power.
There are experts trained at assessing the potential of trees to cause difficulties. Arborists can be certified by the International Society of Arboriculture, and many also are members of the National Arborist Association and the Aloha Arborist Association, which provides educational seminars for its Hawai'i members.
Their goal, said Steve Nimz of The Tree People on O'ahu, is healthy trees. He said yesterday's collapse of a Norfolk Island pine in Manoa should not unduly frighten people who have such trees, but should prod them to have their trees inspected.
"I don't want everyone to cut down their Norfolk pines now that one's failed," Nimz said.
Big Island arborist Michael Kraus of Tree Works Inc. agrees.
"Norfolk Island pines are exceptionally strong trees; they seldom fail," Krauss said. "They do have a tragic flaw in Hawai'i, however. They are not resistant to Formosan termites."
Nimz said the only living parts of trees are the outer cambium layers. The internal wood is there for structural support, and it is the part that termites eat. They can find their way into a tree through a damaged root, but above the surface, you might not see anything amiss.
"A tree can become totally hollow and still look perfectly fine," Nimz said.
Nimz said large trees need proper maintenance and some require a pruning program. He recommended trees be assessed in terms of their possible impact zones if they fall, and in terms of their size. A tree 2 feet to 2 1/2 feet in diameter is probably ready for an assessment by a tree professional, Nimz said.
Reach Jan TenBruggencate at jant@honoluluadvertiser.com or (808) 245-3074.
