Identifying 'killer trees' in Sequoia National Park
In the middle of August, I visit a backcountry campground in California's Sequoia National Park to survey trees. Two teenage boys nap while their fathers roam the nearby woods, looking for firewood. I introduce myself as a forestry technician and mention that a dying white fir is leaning over one of their tents. Dropping my pack, I begin to examine the fir. Are its needles still present; are they green or yellow or brown? Is the bark firm and furrowed, or is it cankered and swollen? Are there dead branches hinged and hanging from the tree, or broken and held suspended in other branches? I jot down the answers, using technical code, then examine the trunk for cavities from woodpeckers, open and oozing wounds, fruiting bodies of fungi, splits or cracks. I scan the base, too, for insect waste, or frass, and look for the mounds around the ground that suggest roots rotting and shearing or snapping. These are all clues that point to arboreal weaknesses.
When visitors ask what I'm doing, I don't say, "I'm using the 7-Point Rating System created by forest pathologist Lee Paine in the 1970s to combine tree hazard rating and target value rating into a probabilistic assessment of structural failure." Instead, I explain that I'm looking at the trees and their surroundings so I can recommend which ones should stay standing, to eventually perish through the nibbling of animals and microbes, and which should go more immediately by chainsaw. But these visitors don't ask me any questions. The fathers in the group respond to my activity with polite smiles, which makes me uncomfortable. Are we not all looking at the same 150-foot-tall, 38-inch-across, 6-point tree hazard?
Millions of people visit Sequoia National Park each year. They come to see the Giant Forest, not giant stumps. At best, park management can provide visitors a safe and educational experience, and it can allow the trees to fulfill their ecological function. Other times, the most we can do is be as systematically subjective as possible. When the trunk of a massive sequoia at the park's southern entrance was found to be just a thin shell of sound wood supporting a rapidly growing spire top, administrators and managers decided to move the entrance station so visitors could still see the tree and the tree could still serve its role in the forest. According to the forester's report, other options included "close entrance station, reconstruct on new site, top/limb tree with helicopter"; "close entrance station, reconstruct on new site, top/limb tree with hot air balloon"; and "close entrance station, reconstruct on new site, top/limb tree with explosives" -- but not "remove entire tree." Because the tree is a monarch sequoia, removing it would require an act of Congress.
It was Congress, after all, that designated monarch sequoias in Sequoia National Park as wonders of the world, and "it is this value," the park's policy states, "that is salient to management considerations, not the lesser fact that it is also a tree." What's a forester supposed to do with that? Can a wonder of the world have butt rot, for instance, or a bark beetle infestation?
Rot or not, I work to prevent giant trees from falling on people or property, and in the public psyche. So when a branch from the 11th-largest sequoia in the world, the over 250-foot-tall Robert E. Lee tree, crashed out of the canopy onto a paved walkway -- avoiding visitors, fortunately, though two people have died in the park from falling sequoia limbs or trunks in the past century -- and was then found to have other weak limbs, my boss' recommendations to close the trail appeared only as a cautionary note, in small print, on the trail sign. To "preserve unimpaired" the visitor's experience, the National Parks Service's fundamental task, meant preserving unimpaired the visitor's access to the Lee Tree. My boss tells me that the sign doesn't deter anyone from tarrying around the tree. "You don't take the boardwalk right up to the goddamn geyser," he fumes.
And you don't pitch your tent under a 150-foot-tall, 38-inch-across, 6-point tree hazard, but I'm not a ranger and I can't tell these visitors to move along. Instead, I pound a metal tag into the tree. I loop one end of caution tape on a segment of bark and walk the circumference of the trunk with the other end. I spray paint a blue dot at the base and a straight horizontal line at breast-height on the trunk, which reminds me of the way people condemned to the guillotine were marked and means a similar fate for the tree. I've done my duty in elucidating the hazard, but my efforts amount to some blue paint and a thin strip of neon orange with alternating images of crossbones and the words Killer Tree. I pack up and hike off to find more precarious facts.
Amy Whitcomb writes from Moscow, Idaho, where the most massive things around are grain elevators.