Ashes felled by invasive pests

They're tall, lush, and in their prime.

Yet within days or weeks, a two-acre stand of ashes - about 100 trees - will meet their demise. Workers will wade into the grove at the Natural Lands Trust's Hildacy Farm Preserve in Media and rev up their chainsaws.

The decision to take down the trees was wrenching, but not difficult. It was the saws or the bugs.

The region's ash trees are in the crosshairs of the emerald ash borer, a glitter-green insect that has chomped its way eastward from Michigan, killing virtually every ash tree in its path.

Unless treated periodically with expensive chemicals, the trees will die. In death, they become brittle. Limbs liable to drop are a safety hazard, and removing the trees becomes more expensive because they aren't safe for loggers to climb.

The trust "isn't in the business of logging trees. We're more into planting trees and preserving trees," said Tom Kershner, its tree management coordinator. But a live tree is more valuable to a logger than a dead tree. The trust could sell the trees now or pay handsomely later.

"It was kind of a no-brainer," he said.

As officials in Pennsylvania and New Jersey prepare for the onslaught of the insect - already detected in both states - they face similar decisions.

They don't necessarily endorse mass logging, but it's happening more and more. In Susquehanna County, after ashes on a Nature Conservancy property were felled and foresters could examine the top branches, they discovered the borer had already invaded. The trees had come down in the nick of time.

Discovered in 2002 in Detroit, the borer is an Asian species presumed to have entered the country on packing material.

Borers kill the tree when eggs that the adults have laid on the bark hatch into larvae, which tunnel into the tree. Often, by the time the borer is discovered, it is too late to save the tree.

For more than a decade, the insect has marched outward from Detroit - jumping wide "fire walls" cut into forests and hitchhiking to new areas on firewood, despite states' firewood quarantines.

The borer was discovered in Western Pennsylvania in 2007. By 2012, it had made it to Bucks and Montgomery Counties. In May, it was discovered in a 57th county, Lancaster.

As a timber tree, the state's white ash ranks about seventh in importance, said Donald Eggen, the state Bureau of Forestry's forest health manager. But it has unusual cachet: Pennsylvania ash is made into the renowned Louisville Slugger baseball bats.

In state forests, workers will treat about 3,700 ash trees so they will survive, the seeds they drop potentially starting a future generation of ashes. As part of a broader national effort, ash seed is being collected and sent to facilities that deep freeze it to keep it viable.

In select sites, the state is releasing Asian parasite species that attack just emerald ash borers.

Last year, the borer progressed to New Jersey. It was detected in Burlington, Mercer, and Somerset Counties. The affected trees were removed and destroyed, "but we know that by the time you find it, it has spread," said Joe Zoltowski, director of the state agriculture department's Division of Plant Industry.

As many other organizations and municipalities are doing, officials at the National Lands Trust are evaluating all their properties to see which ashes are so valuable they should be treated, which should be removed because they could be a safety hazard, and which can remain because they are in isolated areas, such as deep in the woods.

The trees allowed to stand could be important. It's possible some will survive, offering researchers clues about immunity. "We always say 99 percent are going to die," Eggen said. "But what about that 1 percent?"

The Hildacy stand is a monoculture, susceptible to all the ills that entails.

"It's a clear example of the connection between species diversity and forest health," said David Steckel, the trust's senior stewardship planner. "You have a stand that's almost entirely ash, and along comes a single pest that can almost entirely eliminate it in one occurrence."

A more diverse forest would lose its ashes, but otherwise could withstand such an attack.

Funds from selling the lumber will be used to restore the two-acre plot, preserve manager Mike Coll said. He has developed a five-year plan that begins with eradicating the nonnative species tangling the understory, then replanting from the ground up, starting with grasses - the way nature would build a forest. Reintroducing native plants to the undergrowth will help insects and birds thrive.

"In as few as one or two years," Coll said, "this area could be supporting more insect life and other life than it currently is."