Gone: Mass Extinction and the Hazards of Earth's Vanishing Biodiversity
Page 5 of 7
|
|
before i abandon sorting, I discover two worms I'm told are interesting, code for: They might be new species. One is secreted away in formaldehyde in its own vial. The other I'm told to transfer to my sort dish for Brigitte Ebbe, from the Zoologisches Forschungsinstitut in Bonn, Germany, to look at. Strangely, horrifyingly, I lose it. Clamped between the tips of my forceps, it's invisible to the naked eye, and somewhere along the four-inch pathway between examination dish and sort dish it disappears.
I realize this is why no one is enthusiastic about me sorting. I don't tell Brigitte—though someone else probably does. She's a member of a declining species herself, a taxonomist. At a glance, she can tell one identical-looking dorvilleid worm from another, a skill that's being supplanted by costly and time-consuming dna analysis.
A few days later, in the same fashion, Brigitte loses what she knows to be a new species. Just like that.
the last days of the lost hiker in Big Bend's high desert mark the apex of a transient butterfly explosion. Countless millions waft across the desert like bouncing confetti. Southern dogfaces, fatal metalmarks, great purple hairstreaks, American snouts, common buckeyes. Splashes of yellow, orange, blue, purple, and metallic silver flutter by, each with characteristic flight styles: hopping, skipping, low to the ground, erratic as lightning, speedy as bullets.
Scattered among them are the strong, slow fliers with black-veined orange wings. These monarch butterflies are powering across 2,000 miles of North America en route to volcanic mountains in eastern Michoacán, Mexico. None have made this journey before, and each is at least three generations removed from an ancestor who made the reverse northward migration. Nevertheless, as many as 3 billion are homing there now with a surety the lost hiker must envy.
Crossing prairies, mountains, deserts, rivers, wetlands, and woodlands, the monarchs connect these places to each other—changing the locations they visit, being changed by them. Such transfluent energy is good for all parties involved, and satisfies a deep need of wild places. Because the truth is, wildernesses get lonely. Parks and reserves need social contact with others of their kind just as bees and kangaroo rats and people do. They may survive alone, but they do not thrive. Even preserves such as Yellowstone National Park continue to lose biodiversity despite their large size and protected status.
Until now, conservation efforts have rarely addressed this reality. The protected lands we've made so far, 102,102 sites covering 7 million square miles of earth and water, total less than 4 percent of the planet's surface. Many if not most of these isolated fragments are surrounded by hostile neighbors: farms, used-car lots, urban sprawl, clearcuts.
Segregated wildlands experience the same challenges as the dwindling members of an endangered species. Spread too far apart or too genetically weakened, they're cut off from the vital contact that renews and refreshes them, and likewise suffer debilitating arrhythmias in their demographics. Initial species losses are followed by overcrowding, then by population crashes, and insularization, with its attendant biodiversity decline.
The picture is complicated by mysterious realities: that many species will not populate a small wilderness even though it's big enough for their needs. Others will not cross the openings that fragment wilderness, particularly roads, which prove impermeable barriers to many from beetles to bears, either because they refuse to cross or because they die trying. Fragmentation also produces a dreaded edge effect by breaching the protective skin of wilderness, disrupting microclimates, allowing pathogens, alien species, and human development inside, then sealing the edges through the scarification of weed growth.
Ten thousand feet up in Mexico's Sierra Chincua, in dense forests of oyamel firs, arriving monarchs seek protection under heavy evergreen boughs. For millennia, these high-altitude forests transformed monarchs into winter survivors, able to weather five months of deep freeze beneath the insulating canopy. Thanks to the seasonal sanctuary, monarchs can complete the other phase of their lives, and in doing so cinch vast areas of North America from Canada to Mexico, literally connecting the landscape one milkweed bush at a time—helping milkweed to thrive and making monarchs one of the most abundant butterflies on Earth. Species connected to the milkweed economy also prosper, including aphid-farming ants, honeybees, orioles, and moths. Although monarchs do not appear on the Red List, conservation biologists consider their migration an endangered biological phenomenon—a recognition that biodiversity also embraces large temporal and geographical scales: the migration of wildebeest in the Serengeti, caribou in Canada and Alaska, saiga in Outer Mongolia, the synchronous flowering cycles of bamboo in Asia (some at 120-year intervals), the 17- and 13-year cicada emergences in North America, and the annual travels of 1 billion individual songbirds of 120 species between Canada and the tropics.
These are nature's big shows, and they're important to biodiversity. If one phase of a biological phenomenon is disrupted, the consequences are likely to ripple farther and wider than a local species extinction. The gutting of Mexico's oyamel forests by logging, slash-and-burn agriculture, charcoal manufacture, and mismanaged ecotourism do not endanger monarchs overall, because nonmigratory populations inhabit the tropics. Yet the squandering of the forests is a threat to the milkweed trading route, and thereby to the body of North America.
The fragmentation of the Sierra Chincua woodlands is already disrupting the microclimates the migrating butterflies need to survive. At the present rate of deforestation, there'll come a winter night not far in the future when a surge of cold air sinking down from Canada will overwhelm the threadbare forests, scattered too thinly to blanket the butterflies. The only monarchs that know the way north, trapped at 10,000 feet in lonely fragments of wilderness, will die. Just like that.
Photo: Richard Ross
