Rain pushes through the arboretum, relents, and then blusters back in before jackets can dry. No matter. Professional tree-climbers like Bill Conn are used to sizing up hazards and making adjustments.
Squinting through the droplets, Mr. Conn motions toward a red oak where climbers will compete in a timed-foothold climb, ascending 50 feet of rope in 15 seconds. Then he walks to a towering maple. Ribbons flag a series of ever-higher crotches in its branches. The idea: Swing-lob a beanbag attached to a throw line and thread an arboreal needle, the highest of which lies 60 leaf-tangled feet up. A visitor expresses doubt.
"It's easy," says Conn, an arborist employed by Vermont Electric Power Co. and chairman of today's tree-climbing competition, run by the New England chapter of the International Society of Arboriculture. Soon, helmeted men and women stand casting lines upward in graceful arcs that split the uprights.
It might take a minute to buy into tree climbing – main event of many a scraped-knee childhood – as grown-up sport, competitive or otherwise. Nurtured by many of those who make it a vocation, however, it is becoming a mainstream recreational outlet.
"When we started out [in the mid-1980s] there wasn't much going on in recreational climbing at all," says Sophia Sparks, president and co-owner of New Tribe, a specialized-gear and expedition firm in Grants Pass, Ore.
"In the mid-'90s things really started to happen," she says. "[We] broke out from arborists and canopy researchers. More people were moving from working in the trees to playing in the trees."
Since then, Ms. Sparks says, her business has grown 20 to 30 percent a year. Children climb, so do octogenarians. Outfitters have sprouted all over the country.
Tree people – a familial, collaborative crowd – often talk first about safety and then wax Lorax-like about the sanctity of their leafy domain. Minimum-strength standards for their gear are higher than that of the gear used in most rock-climbing, some point out. Dedicated tree ascenders never use spikes – not even on nasty, sap-seeping white pines – unless a human life hangs in the balance.
After that, many promote a more casual offshoot of their favorite on-rope activity: recreational climbing. The sport benefits from a natural abundance of options. You can spend time at a rock-climbing wall, build an ice-climbing facility with a silo and a garden hose. Or, with some solid basic training and about $400 worth of gear you can pretty much step outside – wherever you are – and pick your spot.
"We're a little nervous about [growth in] the Southwest, but even a cactus, done correctly, can probably be climbed," jokes Dennis Furlong, a Bloomfield, Mich., climber. Mr. Furlong runs Arbor Quest, a nonprofit that uses special rigging systems and harnesses to make trees accessible to special-needs climbers. Furlong himself wasn't naturally predisposed to going vertical.
"It took a lot of effort for me to get up there, but it was extraordinarily learnable," he says. "Getting up into the canopy opens up incredible vistas."
Like any form of climbing, it also carries a degree of risk.
"[That's] part of the definition of adventure," says Abe Winters, owner of Tree Climbing USA in Fayetteville, Ga., and a man who can expound (with verbal footnotes) on double- and single-rope techniques and the indispensability of a good Blake's Hitch knot. Mr. Winters now sees some 1,400 climbers per year at his grove, an area with pruned, "tame," climber-ready trees and places to picnic, and elsewhere.
Like many veteran climbers, Winters has both favorite specimens (a pair of signature oaks on his land) and destinations. In Panama he has confronted ceibas that stand nearly 200 ft. tall. "Thirteen people standing shoulder-to-shoulder can't cover the buttress area," he says. "And the first branches are 100 feet up."
Longtime climbers don't agree on any single K2 of trees. But Winters recalls another giant, also in Panama, with smooth bark and thumb-size thorns on the tops of branches. He calls it the Tree of Pain. "If you want to have an experience," he says, "try to climb on something like that."
Many of Winters's most memorable climbs have been local, and peaceful – a swamp in south Georgia where he found an ancient cypress, hollow but still living; or an oak beside a railroad track; or a small tree on a 2,000-ft. north Georgia ridge. A lot of great climbing, he says, is along sturdy horizontal boughs, rather than straight up.
"There are those who want to score the tallest trees," says Sparks, and who look for bragging rights in the redwoods. "But it's really not an extreme sport at all," she says. "What feeds my soul is just being in contact with, and dependent on, the tree. It's about the serenity."
Others go in for the thrill. Among the 20 climbers here today in New Hampshire, Melissa LeVangie – a consulting arborist from South Hadley, Mass., and a repeat women's champion – first saw competitive climbing in Baltimore in 2001.
"I thought, 'I just want to do that,' " says Ms. LaVangie. Her favorite event now: the rescue climb, in which a 150-lb. dummy must be retrieved and lowered gently to the ground.
LaVangie says she has watched interest in tree climbing surge. And she's certain the recent publication of Richard Preston's "The Wild Trees," about the exploration of the redwood canopy, will push interest deeper. "You're seeing people who started out rock climbing and now are saying, 'Gee, I never really thought about trees.' "
The sport has its legends: Peter "Treeman" Jenkins founded the Atlanta-based Tree Climbers International. Tim "Tengu" Kovar, now based in the Northwest, is consider by some to be the sport's Yoda.
In Hawaii next month, 25 to 30 working climbers from around the world will meet at the international event for which this wet weekend event was a qualifier, says Conn. He likes to see the trades represented. He hopes more cities' EMTs will call on climbers when they need a hand; a bucket truck can't always handle the task.
He also draws hope from the hobbyists. Conn owns enough gear for 11 and plans to get a climbing outfit off the ground in six to eight months, once he works out insurance and other issues. There's a lot of forest he wants to share.
"My territory for work is the whole state of Vermont," says Conn. "I see a lot of areas we could get into and get people into nature, get them climbing trees."
For more on where to climb in your neck of the woods, see the "tree links" page at www.treeclimbing.com.