For creatures capable of such momentous landscaping, individual mountain pine beetles-glossy black and less than half an inch long-are unassuming and easily missed. In June and July, adults emerge from pupae and begin the work of killing trees, though from their perspective it's the work of staying alive. Often accompanied by a bluish symbiant fungus that suppresses pine defenses, they bore into the living phloem, blocking nutrient channels and thus starving the trees. The red-needled corpses by the road or trail actually succumbed some time ago, perhaps last season. Unless you know what to look for- sap extrusions on the trunks, say-you might miss this year's casualties. But the beetles don't. When a pioneering female follows chemical and acoustic distress signals to a promising victim beset by drought, age, or previous disease, her compatriots descend en masse. If beetle numbers are high enough, even healthy trees in their path may be overwhelmed. No one is quite certain how these insects find new, distant hunting grounds. Pioneers have proven surprisingly mobile. Whether riding the wind, stowing away in firewood and rough-cut logs, or weaving along ponderosa ridges, mountain pine beetles have shown up far out on the prairie in places as unexpected as Billings city parks, dozens of miles from the nearest mountain.
Temperature and precipitation can ally with either trees or bugs. Larvae and metamorphosing pupae are vulnerable to extreme cold; a few below-zero days at the fringes of the winter season can curtail an outbreak. Shorter winters, on the other hand, extend the beetle's active season, enabling an annual, rather than two-year, life cycle even at high altitudes. Sufficient precipitation can provide trees with enough sap to suffocate or "pitch out" the beetles. Hot and dry weather drains the trees and energizes their attackers. Generally, bark beetle populations track with drought cycles, and outbreaks end when moisture is plentiful. If drought persists, an irruption is likely to continue until mature trees are too few and isolated to support it. That appears to be the case in British Columbia's particularly hard-hit montane forests, where an area four times that of Vancouver Island has turned "red and dead." Forests Minister Pat Bell announced in 2009 that 'The mountain pine beetle epidemic is largely over... The bad news is that it's because they don't have any food left to eat. The vast majority of our pine stands have been killed at this point." U.S. Forest Service regional forest health expert Gregg DeNitto cites a similar dynamic at Montana's beetle epicenter, noting, also in 2009, that in the Beaverhead-Deerlodge and Helena National Forests the outbreak's energy seems to be flagging in the face of a shortage of mature pines.
Drought is endemic in western environments, and one can see the beetles, as Wuerthner does, as nature's agents adjusting water-starved ecosystems to new conditions. If, whether because of human-generated climate change or the poorly understood "long cycle" governing wet and dry periods in the interior West-maybe both-the woods are overstocked, then forests must grow sparser, more open, perhaps withdrawing from some areas completely. This has happened before, more or less. But that more or less is the troublesome thing. Words like unprecedented, epochal, catastrophic echo across Rocky Mountain newspapers. It only takes a glance at the twentieth century to expose a hubristic tendency to cast one's own generational situation as unique and earth-shaking, and today's sensationalistic news media wholeheartedly endorse hyperbole as a matter of course. As with wildfire coverage, television and newspapers redeploy a few dramatic images at the expense of a more nuanced, complete representation of conditions throughout the region. Wuerthner, his activist instincts attuned to the no-holds-barred salvage-logging dreams of timber interests and Forest Service bureaucrats, warns against "beetle hysteria." As of 2009, the outbreak had reddened 2.7 million acres of Montana pines, well short of the 4 million taken by the same bugs in the 1970s and 80s. Even in beetle-ravaged Colorado, a 2006 study led by W. H. Romme, whose past work included a major analysis of the 1988 Yellowstone fires, states categorically that "There is no evidence to support the idea that current levels of bark beetle or defoliator activity are unnaturally high." Unnaturally high, that is, given the combination of drought and "relatively warm temperatures in both summer and winter."
Still, plenty of testimony suggests that something special is afoot. British Columbia's Bell considers himself the first Provincial Forests Minister in history to face "a very real possibility that we will run out of trees." As formerly unusual temperature and precipitation conditions become commonplace, chronic beetle outbreaks could supplant background population levels as the norm wherever and whenever mature pines are available. Logan, McFarlane, and Willcox acknowledge that fears that a 1930s irruption was driving Yellowstone whitebark pines to extinction proved overblown and premature, but only, they argue, because the return of less beetle-friendly conditions tilted the balance back in favor of the pines. Today, "Instead of a short-term weather event, we are experience [sic] a climate trend that started in the 1970s or 1980s and continues unabated."
While the mountain pine beetle is getting most of the press, many tree-eating insects have found recent weather trends to their liking. According to the Summer 2010 edition of Yellowstone Today, the park's visitor newspaper, "Insect infestations attacking trees now include four types of bark beetles and a spruce budworm-a circumstance never seen before. Scientists suspect climate change at work." Park biologist Roy Renkin agrees, asserting that past episodes typically involved limited outbreaks of a single species, and "They've never really been that synchronous to the degree they are now." Scientists list insect proliferation among climate change's likely consequences. Along with fires, bugs maintain the forest's natural regeneration rhythms, and shifts in their behavior or prominence mark a scramble to re-establish ecosystem equilibrium as species jockey for new opportunities or adapt to straitened circumstances created by altered conditions.
Like other denizens of the wild, each bug has its own niche and lifeway. Douglas-fir bark beetles are real catastrophists, their populations exploding in short-lived but destructive outbreaks at the edge of wildfires, blowdowns, and other disturbances. The most obviously denuded area in Greater Yellowstone, characterized by Turner as "an entire forest on the eastern side of the ecosystem near Cody," was scoured by these insects, along with spruce beetles, after the Yellowstone conflagrations. Though ips engraver beetles are less virulent in their attack-many trees survive generations of these bugs-forests subjected to engravers are weakened, and thus open to infestation by deadlier species. Beetles are joined by a variety of arthropod compatriots, such as Douglas-fir tussock moths, pine butterflies, and spruce budworms.
As it turns out, budworms are the most likely agent behind the reddened trees we encountered in Yellowstone's northern range, the Greater Yellowstone Science Learning Center recording a budworm outbreak in the general area of the Lamar and Yellowstone river corridors at the time. Caterpillars of these unobtrusive-looking small brown moths feed on new growth, resulting in burned-out treetops and branch tips. Budworms don't routinely kill their hosts, so it's tempting to take them less seriously than bark beetles, to, for example, feel relief that the northern range damage we found was not from a beetle assault. But repeated budworm defoliation can be quite destructive, especially for young trees with fewer needles to spare. In fact, when bark beetles are at endemic levels, budworms are the most important forest destroyer in both public and commercial timberlands, and the hot, dry conditions favored by beetles are also conducive to budworm outbreaks. Moreover, as with engravers, a budworm surge can leave trees weakened and vulnerable to more lethal bark beetles.
By expanding the range of species under attack, simultaneous depredation by different insects could compromise a forest's capacity to rebound following a large-scale epidemic, especially in places like Yellowstone, where tree diversity is low; many Yellowstone Park forests are composed almost exclusively of lodgepole pine, and even the more diverse woods of the northern range are dominated by a few conifer species. Forests are synergetic by nature, and changes in one aspect of forest life will almost certainly have a range of impacts, some predictable, some less so.
A Canadian research team led by W. A. Kurz concludes that in British Columbia, the pine beetle irruption's "impact converted the forest from a small net carbon sink to a large net carbon source both during and immediately after the outbreak." Rocky Mountain conifers constitute a timbered peninsula depending southward from similar forests across Canada and the entire northern hemisphere. In terms of natural climate regulation, this great evergreen belt is a northern equivalent of the tropical rainforest. The persistence and extent of the ongoing insect epidemic complex has spurred concern that worldwide boreal and montane forests could turn into carbon releasers as dead and dying trees decay or catch fire. The feedback potential is truly mind-boggling. Though it's always dangerous to generalize from a single, if compound, event, the ongoing tree mortality seems a pretty clear sign that even minor temperature shifts-a degree or two here or there-can have far-reaching effects. We don't know enough to identify a definitive indicator that climatic Armageddon is at hand, but it's not unreasonable to suspect that such a signal might look a lot like a British Columbia-worth of dead pines.
What will Rocky Mountain forests be like in a decade? In a century? To even venture a guess engages such profound questions as whether the evolutionary imperatives that created human intelligence will mobilize that vaunted force in time to defuse the climatic meltdown Bill McKibben calls "decreation." In the meantime, a less sweeping application of human ingenuity might be brought to bear on the bugs themselves. As of now, landscape-level responses to bark beetles are impracticable, though individual trees or campground-size parcels can be effectively protected by pesticides and "hormone disrupter packets." A rare upbeat note for whitebarks is that saving some of their more self-contained stands using available means may at least be possible.
Theorizing that auditory cues regulating bark beetle behavior might provide an innovative approach to outbreak control, Northern Arizona University entomologists recently bombarded mountain pine beetles with "the nastiest, most offensive sounds." When a mating pair was subjected to amplified and extended beetle "aggression calls," the results stunned even supposedly dispassionate researchers. Resorting to astonished language reminiscent of nineteenth-century naturalist J. Henri Fabre, team member Richard Hofstetter admits that he and his colleagues "watch[ed] in horror as the male beetle would tear the female apart." The Flagstaff discoveries are promising, if gruesome. But given the now-chronic American disdain for expensive scientific research and development, we're likely a long way from erecting a protective wall of sound around the Rocky Mountains. Basic logistics may well prove unworkable, and complications are almost certain to arise. There may, for example, be a volume or distance limit beyond which beetle vocalizations become unrecognizable to the target audience.
The network of tree-mounted loudspeakers or aerial broadcasts required to mobilize a full-scale sonic assault would place mountain forests under a potentially permanent regime of wholesale human manipulation. In the resulting state of siege, we would hold at best a tentative advantage over adaptively nimble foes: the Arizona team found that their test subjects-unlike the researchers themselves-overcame their initial aversion to Guns 'N Roses and radio commentator Rush Limbaugh, and soon resumed their normal activities. Even if acoustic weaponry could be made feasible and effective, the environmental consequences of such total war would be difficult, if possible, to predict, since bark beetles and their cycles are inextricably tied into the ecology of mountain forests. Like them or not, as much as bears, moose, and the pines themselves, the bugs belong; to eliminate them, even if we could, might beget a nightmare parable against impulsive human meddling. What would Rachel Carson say?
Past insect outbreaks in Yellowstone have been actively fought using methods described by the Casper Star-Tribune as "logging, burning and, in the 1950s, spraying infested Douglas fir with about 62 tons of DDT." Since, as Renkin puts it, such efforts "tend to be futile," the Park Service has opted to view the current complex of epidemics as one more titanic force in the park's evolving, dynamic history. There's something to be said for such restraint. The British Columbia Ministry of Forests and Range lists past fire suppression as a major exacerbating contributor to the severity of the province's beetle outbreak, offering unintended testimony that managerial interference, even if well-intentioned, may be too shortsighted and heavy-handed for finely-tuned natural systems, ultimately doing more harm than good.
Yellowstone managers are staking their hopes on nature reregulating the ecosystem in its own way. Perhaps, aided by growing populations of woodpeckers, predatory beetles, and parasitic wasps, insects and conifers will develop new patterns of coexistence, recalibrating their relationship as they must have done repeatedly since the Pleistocene. Climate change seems to magnify at high altitudes, and just how much stress ecosystems can absorb, and how quickly, and, for that matter, how much the climate will shift, remain to be seen. Nevertheless, the Park Service's decision to refrain from mounting a desperate, potentially destructive offensive against bark beetles and their kin may provide a model for the future. At the very least, their response's humility respects the wildness that has brought generations of nature romantics, myself included, to Yellowstone. A. Starker Leopold recommended that "A national park should represent a vignette of primitive America." As the earth warms, Leopold's pristine, static Eden, an ideal image guiding park management since the 1960s, may be primed to fall before a postlapsarian acceptance of nature as constantly, sometimes uncomfortably, evolving process.
Let's say it's a mid-July afternoon fifty years from now. My great-grandchildren stretch out by a grassy stream on Yellowstone's northern range. If I were there, I might recognize the trickling waterway as, say, Blacktail Deer or Hellroaring Creek. I might note how low the stream is, and wonder what happened to the firs and pines that had interlaced with meadows, sage, and the occasional aspen grove in this part of the park. Interpretive dioramas in the venerable Albright Visitor's Center could already have informed me that it's been years since elk-or wolves-have been seen on the range in summer, and that moose are reduced to occasional wanderers from more intractably bosky climes. Pronghorn, on the other hand, drift across the brushy grasslands in ever-increasing herds. No boreal chorus frogs call from the dry sloughs, their songs replaced by those of Brewer's sparrows and horned larks, maybe Sprague's pipits. As a herd of bison cows and calves sidle through the sagebrush, passing thrillingly close to my descendants' streamside retreat, fingers nervously sifting through dust pull up a footlong shard of barkless wood, a lodgepole remnant.
Would I toss the stick from hand to hand, entranced by its cool balance, wistfully muttering something like "ah, you should have seen this place then"? At best, my perspective would be historical. At worst, I'd just be one more good-old-days grump. And who's to say that my own-that is to say, the current-version of the northern range is "correct"? Historic photographs peg extensive northern range conifer stands as a fleeting phenomenon; past centuries saw broad floodplains, with aspens flanking willow and cottonwood beaver meadows. At any rate, what's to be gained by complaining? This grassy vista is what my descendants know, what they have come here for. Maybe I should just let them enjoy their antelope, their larks, their Yellowstone.
Or maybe the trees will have regrown, the forest reasserting itself as it has for centuries, the bugs subsiding to levels optimal for their own survival, which, after all, depends on the survival of the trees. Past outbreaks have ended surprisingly quickly, and it may turn out that the cycle of red to grey to green will continue for some time, perhaps at an accelerated but sustainable pace. Rocky Mountain lodgepole forests, after all, have withstood considerable climatic variation in regions far south of Yellowstone. Areas torched by the 1988 blazes are generally sprouting replacement forests similar or identical in conformation to their predecessors; even in my great-grandchildren's time, the same pattern may prevail in beetle-kill zones. Or, as in the higher whitebark groves, another species, most likely hardy, budworm-resistant descendants of today's Douglas-firs, might supplant lodgepoles, maintaining an evergreen presence on the range-not the same forest, but a forest nonetheless, with enough cover even for a moose or two.
Late in June, almost a year after our drive home from Yellowstone past the reddened Absaroka slopes, by now probably mostly grey, a new summer's first mountain hike takes us to the Stillwater River, over the Beartooth Mountains from Yellowstone Park. Along the trail, we encounter several Billings people we haven't seen in town for months, amply demonstrating both the pull of the mountains and the irony of driving nearly one hundred miles to spend a day in the wilderness. It is beyond beauty, this northern fringe of Greater Yellowstone, a land of ragged pinnacles, grand plateaus, creeks plunging through hidden ravines, and the season for mountain hiking is painfully brief. To wander these wildlands is why most of us born elsewhere have chosen the Yellowstone country for our home. "The mountains are calling and I must go," says Muir. Who can resist?
Our destination today is Sioux Charley Lake, a few miles above a dramatic granite cleft the river pours itself through just beyond the trailhead. Partially compensating for an el niño winter's meager snowpack, May blizzards and late but generous June rains have swollen the river to a white chaos and left the mountain meadows radiant, paintbrush red and lupine blue punctuating a yellow dazzle of arrowleaf balsamroot. At the lake, really just a broad spot, the Stillwater earns its name, the churning runoff easing enough for a whitetail to swim across as we watch. We don't encounter the moose rumored to be in the vicinity, but the riparian zone is full of life: flycatchers and tanagers calling from cottonwoods, an osprey scouting from a lakeside snag, mergansers napping on a gravel bar, a dipper wrestling a minnow onto a river rock. Though the landscape is verdant overall, a smattering of ominous red patches-the previous year's insect kill-infiltrates the evergreens on higher slopes, especially those not guarded by the black ghosts of lightning fires. If they haven't already, new generations of beetles and budworms will be emerging any day.
Aside from a few surprisingly tall, apparently healthy firs luxuriating in the canyon's ready mist, the Stillwater forests, like most Beartooth woods, are spindly, hardscrabble affairs, stunted conifers gripping bedrock, hunkering much of the year in snow and ice only to be thrust into summers of drought and fire. In the rain shadow of the continental divide, these mountains aren't supposed to look like the ferny glens of the Pacific Northwest. They are, however, our green places. We can hope that each new epidemic will glance off the Beartooths and move on, or, better yet, that a few cool, rainy summers or a timely arctic blast will tip the bugs into background mode, but we can't look at these woods without thinking of other forests reduced to skeletal patterns against the colossal erosional ruins of the mountains. One thing I've noticed is that the already greyed slopes bother me less than the freshly killed red ones. Maybe that's because I'm used to the aftermath of forest fires. Or maybe it's that the demolition is over and the next forest, the next whatever, is already in the works.
One might argue that a kind of juvenile trust in impervious planetary rhythms has gotten us into our current morass. "God takes care of the universe," a woman working a George W. Bush-for-President table once told me when I asked about her candidate's position on the environment. Such an ideology puts nature's fundamental course serenely beyond our purview and enables a pernicious loaves-and-fishes fantasy that everything from timber and oil to the capacity of the earth to absorb abuse is essentially inexhaustible. That being said, faith in nature is a part of our cultural inheritance that I, for one, hold dear. To John Muir, well aware of the human propensity to damage fragile ecologies, the mountains remained unfailing "fountains of life," high places in which we could sense the universe taking care of us, or at least of itself. We will miss the easy faith streaming like Wordsworthian "clouds of glory" from explorers and naturalists who discovered in Yellowstone and the West a wonderland in which to ramble, their confident sense of well-being persisting as a hallmark of later nature writing and nature romanticism in general.
I'd rather be hiking in Greater Yellowstone than doing almost anything else, and I've got to believe that Muir's glad tidings are still out there even in Aldo Leopold's "world of wounds." I can still hear them. But there's no place quite healthy, nowhere we can get away from our own consequences, a complex of intentional and inadvertent effects we'll have to live with, mitigate where possible, forgive ourselves for if we can. It's small comfort to hide behind a divine intent we can neither perceive nor predict. God takes care of the universe? Maybe, but, then again, "The Almighty has his own purposes"-that from an American who knew a thing or two about destruction, responsibility, and renewal.
Places like Greater Yellowstone are not where we go to get away from it all, but rather where we can more clearly see, more deeply feel, our connections, and more viscerally understand the ways in which our lives really do matter. The cost is high for such enlightenment, and it's admittedly shabby compensation to moose and trout, pine and beetle, that will have to pay along with us. The Spanish poet Federico García Lorca credits duende, conditioned in part by the felt presence of death in our midst, with providing human culture its fundamental authenticity, a physical gravitas our mediated modernity at best erodes and at worst actively denies. One thing's for sure: there's a hefty shot of something like duende in a slopeful of dying trees.
In urging a full involvement with existence, Thoreau famously warned against discovering when one comes to die that one hasn't lived. Easy for him to say, back when there was still so much flourishing wildness-"the preservation of the world"-just over the horizon, in, well, Yellowstone, for example. But his contemporaries' bemusement shows that even then it was not easy to break the membrane separating what we know from what we live. To do so is to emerge face to face with one's own enmeshment, one's own complicity, in things as grand and beyond comprehension as the birth and demise of forests, life and death on a scale both intimate and planetary. To return, in other words, to the evolving numinous wilderness in which our lives are, and have always been, made . In our time the news emanating from the mountains is ambivalent, even frightening; Muir's call to get those tidings firsthand may lead not only to ecstatic peaks but also to perilous valleys of disillusionment. Never, though, to the dead-end ledge of a false detachment.
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