5 1/2" x 8 1/2"
8 b&w illustrations
Co-published with David Suzuki Foundation
Empire of the Beetle
How Human Folly and a Tiny Bug Are Killing North America's Great Forests
Chapter Seven: The Song of the Beetle
“All things move in music and write it.” —John Muir, letter to Jeanne C. Carr, Yosemite
During 2005, David Dunn often wandered the hilly outskirts of Santa Fe looking like a medieval plague doctor. Armed with headphones and a tape recorder, the avant-garde music composer and violin player poked the thin bark of pinyon trees with a special homemade device. The odd contraption consisted of a meat thermometer and a piezoelectric transducer from a Hallmark greeting card. After inserting the modified thermometer-cum-microphone into the tree’s inner bark, Dunn patiently listened to the voices inside the tree. The bespectacled artist made an ungainly apparition in the desert forest as he perched against trees for hours on end.
Dunn became a tree whisperer after New Mexico started to lose half of its famed pinyon trees to an unprecedented beetle outbreak. Anxious landowners wanted a clear diagnosis on their trees before they pulled out their chain saws. Because Dunn had the listening tools, he got recruited for the job. Whenever the sound engineer heard noises that resembled running water or creaking winds in a pinyon, he’d give the tree an all-clear for beetles. Such a diagnosis inevitably invited two possible prescriptions: the landowner could water the tree more often, to build resin resistance, or he or she could spray the pinyon with the pesticide carbaryl. If Dunn heard squirrel-like pops and clicks, that meant the beetle had taken up residence and was now building its own magical sound universe. Such a diagnosis invariably resulted in someone pulling out a saw. When people offered to pay for his unique service, Dunn gracefully accepted a donation on behalf of his nonprofit Art and Science Laboratory. Dunn, after all, was collecting data on one of the world’s most remarkable animals for one of the strangest and most unlikely of science experiments.
Dunn’s otherworldly investigation began in summer of 2003, when clouds of Ips confusus alighted on the pinyons. The beetles turned the trees a deathly ocher, and then a Halloween gray. The musician’s neighbors started to panic, but Dunn got curious and cobbled together his odd-looking microphone. “I felt there was an exceptional amount of biological activity going on, and I wondered if there would be any sound in the tree,” he recalls. He discovered a richer acoustical world in pinyons invaded by polygamous beetles than he could have ever imagined. It was like encountering a skilled percussion group in the middle of the Mojave Desert. All the clicks and pops prompted the illustrious artist to ask a series of questions that scientists rarely ask.
Dunn started with the stories of Pueblo elders, who believe that “the beetles come when the trees cry.” He wondered if that was true, and, if so, how a pinyon might weep. He was also curious about how bark beetles communicated in their winding galleries. Why did scientists know so little about the insect’s acoustic abilities? Could the death of beetle-riddled spruce trees in Alaska be related to the pinyon-killing drought in New Mexico? His list kept growing.
Ips confusus, the innocuous pinyon engraver, set Dunn off on a seven-year investigation into scolytids, climate, beetle music, and complexity. In his spare time, Dunn diagnosed infested trees. The art world “needs to ground people’s imaginations in a deeper understanding of the natural world,” he believes. “I think it is essential at this point that artists take a role in collaboration with the scientific world—that artists and scientists work together towards real-world problem solving. We need all the help we can get.”
Dunn’s reflections produced some radical conclusions. Given the insect’s evolutionary success and its ability to change entire landscapes at the drop of a hat, Dunn thinks bark beetles might be one of the most important animals on earth. “They are amazing creatures. They eat themselves out of a food source. That’s a terrifying proposition.” After producing a highly unusual beetle CD called The Sound of Light in Trees, Dunn began a wildly inventive collaboration to test an innovative idea: acoustic warfare against beetles. The results could change the entire field of pest management. “We altered beetle behavior by playing back their own sound,” explains Dunn. “We managed to turn them into cannibals. We created unprecedented behaviors.”
Dunn’s beetle odyssey took place in one of the West’s most ancient and important woodlands. A pinyon juniper forest may look like a bunch of stubby trees on a model train set, but it defines the soul of the southwest. About six species of the aromatic juniper shade eleven different kinds of pinyon pine in these semi-desert lands. Most common among the pines are the Colorado pinyon (Pinus edulis) and the single-leaf pinyon (Pinus monophylla). A juniper, which has the longest roots of any tree, can live for 1,200 years. A pinyon can grow up to 800 years old. The random cowboy marriage of pinyon and juniper can take place in a variety of landscapes, including dense forests, shrub lands, and open savannas.
Hardy pinyon juniper woodlands now cover about 89 million acres of dry and sandy tablelands throughout California, Utah, Arizona, Colorado, and New Mexico. Sandwiched between desert and high alpine groves of ponderosa pines, these old forests shrink in hot weather but expand during cool, rainy times. The apple-shaped pinyon not only provides shade for coyote and antelope but protects critical watersheds on mountain slopes. About one thousand different plants, insects, birds, and mammals live in a pinyon juniper forest. The pinyon, however, is one of the slowest-growing pines on the planet. It takes sixty years to reach a height of six feet and about a century before the tree can produce a good crop of nut-laden cones. Edward Abbey, the famous forest ranger and writer, often rested in the shade of a pinyon tree just “to admire the splendor of the landscape and the perfection of the silence.”
For nearly ten thousand years, the Hopi, Shoshone, Pueblo, Numu, and Navajo well understood the worth of the pinyon tree. The nut gatherers basically managed Pinus edulis and Pinus monophylla forests as nut orchards. They thinned and fired the forest to ensure mixed-age stands of high-producing nut pines, and for good reason. Rich in protein, fat, iron, and vitamin D, the pinyon nut is a civilization builder and a culture maker. Ronald Lanner, the U.S. naturalist and former forest researcher, notes that the Colorado pinyon nut provides more calories than a “pound of chocolate and nearly as much as in a pound of butter.” The nut also contains more essential amino acids than cornmeal does. Bushels of the nuts have sustained desert communities in times of scarcity. (Abbey thought the pinyon nut was as sweet as a hazelnut.) The so-called desert manna makes not only a long-lasting flour but fine soups, stews, and porridges. After the rainy season, the abundance of pinyon nuts can energize the forest in a magical way. Following a good nut year, explains one pinyon gatherer, “you should see the mice and then the coyotes. Then the raptors. It comes in a huge pulse, and it all goes back to the pinyon.”
Gathering pinyon nuts in the fall was a joyful and celebrated event. John Muir witnessed the energy and splendor of a nut-gathering expedition by Mono Lake in 1870:
“When the crop is ripe, the Indians make ready the long beating-poles; bags, baskets, mats, and sacks are collected; the women out at service among the settlers, washing or drudging, assemble at the family huts; the men leave their ranch work; old and young, all are mounted on ponies and start in great glee to the nut-lands, forming curiously picturesque cavalcades; flaming scarfs and calico skirts stream loosely over the knotty ponies . . . Arriving at some well-known central point where grass and water are found, the squaws with baskets, the men with poles ascend the ridges to the laden trees, followed by the children. Then the beating begins right merrily, the burs fly in every direction, rolling down the slopes, lodging here and there against rocks and sage-bushes, chased and gathered by the women and children with fine natural gladness. Smoke-columns speedily mark the joyful scene of their labors as the roasting fires are kindled, and, at night, assembled in gay circles garrulous as jays, they begin the first nut feast of the season.”
For hundreds of years, many tribes traded the famine-fighting protein across the West and into Mexico. Until the 1930s, millions of pounds of nuts went to markets in New York and Los Angeles. Today, thanks to globalization, most Americans are stuck buying foul-tasting pinyon nuts from China, Korea, or Russia.
White settlers didn’t appreciate the cultural significance or the pulse of the forest. Most pioneers singularly valued the short pine as fuel or fence post. For nearly two hundred years, mining companies clear-cut miles of mature pinyons to make charcoal for silver smelters. For most of the last fifty years, ranchers looked upon the aggressive juniper and the scrubby pinyon “as weeds in need of eradication.” As a consequence, land managers knocked down more than a million acres of pinyons with cables and chains tied between tractors. Since the 1980s, strict fire management has increased the density of surviving stands and allowed wealthy Californians to invade the forest with monster estates and gated communities.
That’s how bark beetles found the pinyon juniper forest in 2002: abused, fragmented, unappreciated, crowded, and dried out. The Southwest boasts the largest diversity of tree engineers in North America. As many as ten different species of bark beetles typically manage pinyon, ponderosa, and lodgepole pines throughout the region. They include Ips confusus (the pinyon engraver), the western pine beetle, the southern pine beetle, the mountain pine beetle, the round-headed pine beetle, and several twig beetles. Where the western and southern pine beetle and several Ips species led the charge against millions of ponderosa pines in 2002 in Arizona and Colorado, the Ips, accompanied by two twig eaters, exploded among the pinyons of New Mexico.
Ips confusus doesn’t normally go on wild killing sprees. Tellingly, Stephen L. Wood gives the creature scant mention in his scolytid bible. Unlike the predatory mountain pine beetle, the Ips is an opportunist that takes out individually stressed or injured pinyons. The male leads the attack and then is joined by four or five females along with the usual crew of mites, nematodes, and various strains of fungi, including the classic blue-stainers. Ips larvae primarily feed on the phloem of the tree and carve long-winding galleries under the bark.
A good drought, however, threw both trees and beetles off balance. The dry spell descended on the Southwest in the mid-1990s, after twenty years of wet weather, and didn’t let go until 2005. On average, a pinyon tree needs nine to fifteen inches of rainfall a year to thrive. The drought reduced that intake to next to nothing. Compared to a previous drought, from 1953 to 1956, this one delivered hotter weather. The soil water content got so low that pinyon trees stopped transpiring and photosynthesizing altogether. At the Los Alamos National Laboratory, ecologist David Breshears could look out his window at a pinyon study plot the size of a football field and actually watch the trees die. “I would see the trees go from vibrant green to pale, gasping green to pale brown to dropping all their needles,” he remembers. Between 2002 and 2003, the die-off was so extensive that patches of graying trees could be seen from outer space. It extended over 4,600 square miles, an area the size of Germany’s Black Forest.
Drought-stressed pinyons gave the engraver beetle an opportunity to run riot in a landscape of undefended castles. The mild-mannered Ips normally reproduces two generations a year. During the drought, some populations reproduced as many as five times annually. “There was an exponential explosion,” explains David Dunn. In 2003 alone, the outburst reached an Alaskan scale, covering 800,000 acres in four states. At the time, local ecologists called it a perfect storm of tree death: “excessive foliage and biomass produced during the wet years of 1976–1995; a severe and prolonged drought that limits their capacity to resist normal insect attacks; and tree-killing native insects whose populations are growing exponentially as a result of unusually warm weather.”
Like all bark beetle uprisings, the Ips revolution caught everyone by surprise. In 2002, the beetles browned the pinyons on the Sangre de Cristo Mountains outside of Santa Fe and wiped out 90 percent of the pinyons around Los Alamos. The city of Santa Fe hastily cobbled together a “pinyon initiative,” declaring, “It’s hard to imagine that an insect the size of a grain of rice could become public enemy number one in Santa Fe, but this is how many have felt about Ips confusus, the piñon bark beetle.” The creature predictably generated heated debates about falling property values, pesticides, the cost of dead tree removal, and the threat of wildfire.
As in Alaska and British Columbia, authorities generally exaggerated the risks of wildfire as well as the benefits of cutting dead trees. An unusual public letter released by a group of forest ecologists clarified matters. The ecologists estimated that the fire risk would remain high for only a year, until all the trees’ needles fell off. Thereafter, “future fire hazard even in the most heavily affected areas will likely be no greater than before the mortality event, and probably will be reduced because of the substantial decline in canopy fuels.” In contrast, they said, cutting down dead trees would accelerate soil erosion and encourage the invasion of cheat grass, an Asian fire-loving invader that saps the western landscapes of all vigor and moisture.
The Ips storm was unlike anything entomologists had seen before. Mike Wagner, a jovial, ruddy-faced researcher at Northern Arizona University, found engravers as thick as Canadian blackflies just ten miles outside of Flagstaff. “I was on a field trip in the forest, and every time I opened my mouth a bark beetle would fly into it,” says Wagner. It was like an insect hurricane blowing through the mesa. Hundreds of beetles would bore into the boles of the pinyon, and thousands of their offspring would emerge shortly afterward to attack new trees. The populations grew so dense that not a living pinyon of any age remains. In the space of two years, drought and the beetle converted a pinyon juniper forest into a juniper forest. And the junipers also got hit: the twig beetle, Phloeosinus, mauled the tops of many surviving trees. “What astounded me was the speed with which the beetle converted the forest,” Wagner remembers.
By the time the beetles approached David Dunn’s home in Santa Fe, they had finished off 55 million drought-stressed trees, 10 percent of the state’s forests. Although Dunn knew little about bark beetles or their acoustic life then, he already understood that the natural world was startlingly musical. In 1990, he had released a series of underwater recordings taken from insect activity in ponds. The creatures, including a variety of water beetles, made wild tropical-like rasps and sputters. “Their alien variety seems unprecedented as if controlled by a mysterious but urgent logic,” wrote Dunn in his liner notes. He called his CD Chaos and the Emergent Mind of the Pond.
As Dunn’s Chaos CD amplified, insects do a lot more talking than scientists initially thought. With the aid of sensitive digital technology, researchers can now hear insects rubbing together a variety of body parts (an act called stridulation) to make a host of unique sounds. A recording of two thousand eastern subterranean female termite workers, for example, sounds a lot like a dentist working on a tooth cavity. The sounds made by palm weevil larvae call up the image of a dyslexic Morse code operator.
At first, Dunn had thought that bark beetles were a largely mute group. But then the musician came across a series of interesting studies on mountain pine beetles done in Oregon in the 1970s by Joseph Rudinsky. Rudinsky found that courting males struck up an aggressive chirp to attract mates or to ward off rivals. They did so by rubbing a sound organ on the back of their heads, called a pars striden, against the main part of their bodies. (The pars striden works like a gyro or percussion instrument with ridges on it.) Rudinsky had also noted that acoustic signals could set off chemical cues, and following that the focus of beetle research shifted to these chemical perfumes. Given that beetles don’t fly at night (and therefore don’t have to fear bats), researchers thought it highly unlikely that bark beetles possessed any ultrasound receptors. To Dunn, though, it appeared that scientists had opened a door on the acoustic ecology of bark beetles and then covered their ears. According to recent research, “the diversity of sound-producing organs in beetles is amazing and unmatched by any other order of insect.”
Dunn had the idea of retrofitting a ten-dollar meat thermometer to act as a microphone, with the hollowed shaft serving as a wave guide. The piezobender disc, taken from a greeting card, acted as loudspeaker. Dunn, who now exports this beetlelistening device to Chinese researchers, first planted the tool in the phloem layer of a pinyon tree by his home in early spring of 2003. He recorded silence. The tree creaked in the wind, but that was it. After temperatures got warmer, he waited two weeks and then tried again. This time, he heard stirrings, pops, chirps, and clicks. The phloem and cambium layers of a pinyon tree “are an amazingly effective medium for acoustic communication,” he says. Over the next two years, Dunn made recordings at hundreds of pinyon trees. He was able to do something few beetle academics have done: listen unhurriedly to the deliberate and chatty work of scolytids in the wild.
Some days Dunn inserted his recorder near nuptial tunnels, other times near pitch tubes. He discovered that stridulation “can go on continuously for days and weeks,” long after the beetles have mated and excavated their tunnels. All of this talking suggested to Dunn that the beetle not only had “a more sophisticated organization than previously suspected” but also used perfume trails for long-distance communication in the forest, then switched to stridulation for short-distance chats inside trees. In fact, he discovered, the beetles created an endless chatter in young and old trees at almost every time of the year except winter. “The beetles weren’t even quiet at the end of summer.”
Dunn carefully noted the condition of the trees he tested, recording the color of their needles and the number of pitch tubes on the trunk. On severely stressed trees, the beetles bored through bark without encountering any resin resistance at all, noted Dunn. Trying to save an attacked tree seemed futile, since “it doesn’t take long for a beetle to take a tree down.”
Dunn discovered during his investigations that pinyon trees several hundred years old appeared to have an entirely different relationship with the beetle than did younger trees. Most of the elders had survived previous beetle visitations and had some sort of resilience. Some of their branches thrived though others seemed dead. But big concentrations of beetles still settled in these old trees. “Their behavior [there] was entirely different, as though they had entered an equilibrium state. They hadn’t killed the tree but had established themselves. It was though something else was going on,” Dunn recalls.
The trees made their own sad music. A parched pinyon typically produces a variety of powerful pops that sound like distant drumbeats. Botanists call this collapse of cells “cavitation” and use it as a measure for drought stress. Healthy trees pump water from their roots to needles via a series of pipes in the xylem. The system works under negative pressure. During a drought, air bubbles form in this vascular system, creating a sort of tree thrombosis. The cells eventually collapse with a popping sound. “They can implode with such tremendous instantaneous force that, under laboratory conditions, they have been measured to produce temperatures up to five thousand degrees centigrade,” says Dunn. These cavitation events release both light and sound signals that fall between an audible range (twenty kilohertz) and an ultrasonic range (two thousand kilohertz). The human ear can hear frequencies up to twenty kilohertz, but many insects can detect up to two hundred kilohertz of sound. Dunn and a growing number of scientists suspect that bark beetles may home in on these cavitation signals. As the Pueblo put it, the beetles hear a tree crying in an arid land.
The Sound of Light in Trees, the CD Dunn made from his pinyontree recordings, showers listeners with bizarre beetle sounds. Alien clicks and rude tweets seemingly rise above an orchestral background of drying wood. The stridulations of the Ips beetle in the castle of a pinyon sound alternatively subterranean and watery. Many of the squeaks and clicks call to mind an old man sitting in a rocking chair in another room, cleaning his briar pipe with a shank brush.
About the same time as David Dunn was making his beetle recordings, Reagan McGuire, a fifty-six-year-old truck driver, pool hustler, and genuine character from Pittsburgh, read an article about bark beetles killing 74 million trees in Arizona and New Mexico. “I thought that was a lot and wanted to do something about it. I’m a tree hugger. I love trees,” McGuire says. He recalled how the U.S. military had blasted Panama dictator Manuel Noriega out of his refuge in the Vatican embassy by playing heavy rock music day and night. (The blasting also drove the Vatican crazy.) Similar long-range acoustic devices were used to deter Somali pirates. McGuire, a freethinker, wondered if he could create the same kind of acoustic stress in a bark beetle. He called up Richard Hofstetter, the young beetle specialist at the University of Northern Arizona in Flagstaff. Hofstetter listened during a meeting with McGuire, though “he looked at me as though I was crazy,” McGuire recalls. McGuire kept going back. Eventually Hofstetter, who studies the mites and fungi on the beetle bus, found some money and put McGuire to work in a lab at the university’s forestry building, which is surrounded by ponderosa pines. Given the dismal history of bark beetle control, Hofstetter reckoned it wouldn’t hurt to try something completely different.
While doing background research, McGuire came across Dunn’s Sound of Light in Trees on the Internet and shared it with Hofstetter. The incredible range of chirping sounds convinced Hofstetter that the bark beetle had a much more complex way of communicating than previously thought and that McGuire wasn’t crazy after all. McGuire visited Dunn for a week to learn how to record beetle sounds in trees. The two often talked through the night about beetles, music, aridity, and life. Since then, the entomologist, the musician, and the pool hustler have collaborated on one of the craziest science experiments in insect history.
In his lab, Hofstetter fashioned a “phloem sandwich” so that McGuire could view his beetle subjects while filming and recording their reactions to different sounds. This beetle version of an ant farm consists of two quarter-inch-thick plates of Plexiglas with a piece of sugar-rich phloem inserted in between. A single hole allows a beetle to enter its favorite realm. Although the phloem dries out quickly, the sandwich gives researchers a clear view of beetles doing their thing. The first time Hofstetter used a sandwich, he watched mites eat a bunch of beetle eggs.
To start off the experiments, McGuire played the most abrasive sounds he could think of: heavy metal and, amusingly, angry monologues by Rush Limbaugh, the infamous talk-radio host. “I wanted an authoritative, agitating, and repeatable voice I could play back again and again. I also wanted to stress the hell out of the beetles, and I thought that hate radio would do it,” McGuire explains. (Hofstetter, a gentle man of Canadian ancestry, later posted a disclaimer on his website explaining that the use of Rush Limbaugh’s voice “was not a political statement.”)
But the beetles in the phloem sandwich ignored Limbaugh’s bombast. The beetles didn’t react, either, when McGuire played the man’s voice backward. “They’re smart critters,” adds McGuire, who basically learned the essentials of bioacoustics and entomology on the job. (At first, he couldn’t believe how delicate the beetles were: “They are really amazing creatures. They are dogs of war, yet very fragile. I don’t hate them. I just want to kill them.”) The beetles also ignored head-banging tunes by Metallica, as well as Guns N’ Roses’ “Welcome to the Jungle.”
Hofstetter then proposed that the team try playing more beetle-like sounds. That’s when things got really interesting. (Ips appear to have as many as five distinct calls that range from one click to a series of Morse code–like chirps.) They first put a female pine beetle in the sandwich and then introduced a male to the entry hole. The male promptly stridulated with a chirp sound saying “I’m here. I’m here.” Then McGuire played the sound of another male chirping. The female promptly abandoned the real male in a vain attempt to find the louder but virtual source. “In one case, she tunneled to the speaker and waited. We changed their reproductive behavior completely,” says Hofstetter.
Another experiment highlighted the power of bark-beetle voices in a grim way. Both Hofstetter and Dunn wondered why there were no hybrid beetles in Arizona, given that the western and the southern pine beetle often attack the same ponderosa tree. To find out, they parked a female western bark beetle in a phloem sandwich, then introduced a male southern pine beetle. “The female started signaling by making weak pulsing sounds. The male moved towards her and started to make a terrifying loud stridulation sound. The female froze in her tracks. Then the male came up to her and chewed her in half lengthwise. It was sonic warfare,” says Dunn.
After McGuire had recorded and modified the squirrel-like screech of the male southern pine beetle (a heart-rending sound), he played it back to a pair of western pine beetles. He watched a male mate with a female two or three times and then suddenly chew her to pieces. “You know, you don’t see that in nature. That’s not natural.” In another study, a desperate southern pine beetle male chewed his way through the Plexiglas. He continued for two weeks after McGuire stopped playing the sound. “His mandibles were reduced to stubs,” says McGuire. “It was extraordinary.”
Sitting in a narrow room full of dried-up beetle sandwiches and piezo recorders, McGuire patiently documented which of the modified sounds drove beetles most crazy. He manipulated beetle voices to disrupt mating, tunneling, and reproduction. He even watched six male and six female Ips beetles tunnel in circles and avoid sex altogether. Patents are now pending on some of the sound recordings. A beetle audio device the size of a smartphone that can be fitted onto a tree is being field-tested. “If we can reduce the fitness or fecundity of beetles by even a fraction, it will be helpful,” says Hofstetter. When the team released some preliminary findings in 2010, the media cranked out four hundred stories with headlines such as “Not Everyone Likes the Beetles’ Sound” and “Bark Beetles Rocked by Sound.” Many articles highlighted how useless Limbaugh’s voice had been in the beetle fight.
If beetle sounds can defeat scolytids and temper their foresteating behaviors, Hofstetter’s team could change the course of entomology. Instead of poisoning termites, ants, cockroaches, and other pests, people might limit these tidy empires with sonic fences or disrupt their mating practices with horrific insect yells and shrieks. Protecting stored grain supplies could become as simple as flipping a switch. “Acoustic ecology could change the way we do pest control,” admits Hofstetter.
After the great pinyon die-off, the New Mexico government published a report in 2005 on how climate change will affect the state. The report concluded that there would be less snow, regular water shortages, more beetles, fewer trees, and greater uncertainty. The paper included an unintentionally droll paragraph on the hazards of rapid change:
“Surprises are inevitable. New evidence from paleoclimatic records now show that climate changes and ecosystem responses are not always gradual, but can occur abruptly over a few decades or less. Complex human and natural systems often respond in a nonlinear manner to increasing stress. That is, they change gradually or not at all until a threshold (“tipping point”) is reached, and then they change dramatically. Positive feedbacks can amplify the impacts of small changes into enormous effects, such as when a wildfire grows slowly until it begins creating its own winds and “blows up” catastrophically.”
The massive scale of tree death so impressed researchers at the University of Arizona that they dug up twenty mature pinyons and replanted them in Biosphere 2. It’s a futuristic glass-enclosed facility, a sort of mini-earth, where scientists can study coral reefs, mangrove wetlands, and savanna grasslands under controlled conditions. The researchers put half the trees in an enclosure set at normal New Mexico room temperatures. The rest of the trees were placed in a room where the thermostat was jacked 7 degrees Fahrenheit above normal. These trees got a climate-change warming shock, which scientists predict will be the West’s new weather of the future. Then scientists stopped watering both sets of trees.
The results of the experiment explained a few things about the great pinyon mortality. Drought killed the trees in the climate-warming room 28 percent faster than the pinions exposed to normal temperatures. The trees stopped breathing and died. Given the region’s hundred-year drought record, the scientists projected, that meant pinyon die-off would occur five times more frequently due to hotter weather. “I don’t want to be alarmist, but that is a super-conservative projection, because the result relates only to temperature, not to increased drought or bark beetles, which we know will exacerbate the problem,” explains David Breshears. “So we could be in for a lot more change.” With beetles in the picture, tree mortality could actually double.
David Dunn believes that bark beetles illustrate the evolutionary range of human experience, from drum-beating hunter gatherers to orchestral farming civilizations. He views Dendroctonus as a fairly primitive step in beetle evolution, with only one or two sound-generating organs. “They are monogamous hunter-predators. They take down a tree.” Dendroctonus are such committed predators, however, that they can use the chemical signals of a tree as a weapon against itself. And the Ips, he muses, are much more sophisticated. “These so-called secondary species have an entirely different mating strategy and a different relationship with fungus.” Because Ips are more interested in farming than in killing, they communicate more fluidly in a tree. They play different organs on their bodies to make sounds. Last come the ambrosia beetles. One clan peacefully farms fungi in healthy eucalyptus trees in southwestern Australia. “They have a totally controlled environment and are very protective of trees,” Dunn says. The ambrosia beetles, led by a queen, excavate tunnels in the heartwood, where they garden fungi and lichens for decades. The daughters of the founding queen, a group of infertile Amazons, clean and defend the garden beetle society with the devotion of cloistered medieval nuns. They never leave the tunnel. “The real value of looking at bark beetles,” explains Dunn, “is that they are a fascinating form of life. They can also be the most destructive form of insect life for sheer scale of effect on the planet. And they can change a forest unlike any other creature. That makes them an important species to pay attention to.”
Together with the physicist James Crutchfield, a specialist in chaos theory, Dunn worries that bark beetles may also become novel players in global warming. Crutchfield owns some land in New Mexico, where beetles took out nearly a hundred trees, and has partnered with Dunn on a number of music and beetle projects. The chaos theorist and the musician calculate that the bark beetle has the potential to be not just a quick responder to higher temperatures but a generator of carbon, based on a number of feedback mechanisms. Their reasoning goes like this: As more trees die, less carbon is sequestered and stored. The disappearance of forests, in turn, leads to the generation of less oxygen and the concentration of more carbon in the atmosphere. As the release of more forest carbon causes temperatures to rise further, the warming will put beetles on the landscape in ever-greater numbers and ever-expanding geographies. Crutchfield and Dunn call it entomogenic change. “Things have the potential to run away on us.” says Dunn. “Things that seem in balance may go off the scale.”
It is not an idle theory. The drought and the beetle die-off in the pinyon juniper forest changed the region’s entire carbon budget. According to one 2010 study, the U.S. Southwest lost more carbon from the beetle/drought die-off (an estimated 5 million tons) than it did from wildfire or logging over the same period. Spruce, lodgepole, and Douglas-fir forests generally hold two to three times as much carbon as the slow-growing pinyon. But beetles have dramatically whittled the capacity of those trees to hold carbon.
Dunn doesn’t know where the bark beetle will take his own art or how the insect will ultimately redesign the earth’s forests and climate. He hopes that sonic warfare will eventually calm the beast in the forest. But the artist knows that he has surely met a charismatic creature like no other, a Beethoven among insects. If nothing else, the beetle should remind us, says Dunn, that we are all part of nature; we come from the natural world and will live or die depending on our generous understanding of that world. Like the Babylonian beetle empires now rising and falling in our forests, human civilization has abruptly experienced collapse, and will again. The problem with nonlinear change (and neither human nor bark beetle empires move in a straight line) is that “there is no off switch,” says Dunn. “We can’t reboot the software.” He suspects that the sound of the beetle in drought-wounded trees heralds profound transformation. He pauses before he adds a final thought. “The changes probably won’t be good for us.”
© 2011 D&M Publishers Inc.
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