cultivation rises from 15 percent (in districts with scant precipitation) to over 99 percent (where conditions are most conducive to crop production). And in the tall grasslands, with their relatively generous climate and deep, black earth, as much as 99.9 percent of the native grasses have been plowed under to make way for agriculture. Largely as a result of this destruction of natural habitat, at least 464 prairie species have declined to such rarity that their long-term survival is in question, and more names are added to the list with every passing year. (This tabulation includes only species that have been officially designated as at risk of extinction, either locally or nationally.) Of this total, a majority are unique organisms found exclusively, or almost exclusively, on the Great Plains grasslands.
The Foothills Grasslands of Waterton National Park, Alberta, bask in the autumn sun. This ecoregion not only benefits from the trailing edge of storms borne over the mountains but also enjoys relatively mild and bright winters, thanks to the influence of chinook winds.
These trends are deeply troubling, and we could easily get lost in the dark. To find our way forward we will have to be sure-footed, willing and able to move quickly from sorrow to hope, from past to present, from celebrating wildness to accepting and honoring our own accident-prone presence. We will need to see both the splendor of the life that has faded away and the abundance that still extends across the whole wide world of the prairie in every direction. For however diminished, the Great Plains are blooming and buzzing and wriggling and squirming with wildlife wherever we look. In the Northern Mixed Grasslands ecoregion, for example—where as much as three-quarters of the natural habitat has been lost to the plow—there are currently no fewer than 13 species of amphibians, 18 reptiles, 72 mammals, at least 160 butterflies, 222 birds, and 1,595 species of grasses, sedges, and wildflowers. This gives the region a total “species richness index,” on the books of the World Wildlife Fund, of 2,095, much higher than many areas that are typically thought of as biodiversity hotspots. (By comparison, the rain forests of northern California have a richness index of only 1,710, while the Everglades come in at 1,855.)
On the Southern Short Grasslands, by comparison, where significant areas of natural grasslands remain intact as grazing land, the picture is brighter yet, with 17 species of amphibians, 61 reptiles, 86 mammals, 230 butterflies, 245 birds, and an astonishing 2,359 species of grasses and other nonwoody plants, for a richness index of 3,011. Although this book can’t introduce you to all those species—you’ll need the appropriate local field guides for that—it will explain how this abundance of life is sustained and renewed, season after season. Far from being a sacrifice on the altar of progress that we can dismiss from our thoughts, the prairies are still very much alive and worth caring about.
About This Book
In the riotous interactions of nature, everything happens at once—sun, wind, rain, growth, birth, death—and change ripples organically through the ecosystem. For the purposes of discussion, however, it has been necessary to isolate aspects of this holistic system and discuss them one by one, each in a separate chapter. Although the subject matter is tightly interrelated, each section has been designed to stand on its own, so the chapters can be read individually and in any order. Chapter 3, “The Geography of Grass,” for instance, provides a detailed look at the prairie grasses and their dynamic relationship with the extremes of a midcontinental climate. Chapter 4, “Secrets of the Soil,” ventures into the dirt—a life zone all its own—and introduces a few of the strange little creatures that live beneath the ground. In Chapter 5, “Home on the Range,” we come back out into the sunshine to ride through cattle country and find out how life is lived on the surviving expanses of native prairie. Chapter 6, “Water of Life,” by contrast, takes us knee-deep into the nearest prairie river or pond to look into the lives of ducks, shorebirds, fish, and other aquatic organisms. Chapter 7, “Prairie Woodlands,” examines the unexpectedly important role of trees in grassland ecology and asks what difference it makes that woody growth is now invading the prairies. Chapter 8, “The Nature of Farming,” studies the potential and challenges of croplands as wildlife habitat. And finally, Chapter 9, “Long-Range Forecast,” reconsiders the conservation status of the Great Plains—is this really the most endangered ecosystem on the continent?— and discusses a range of options for protecting and restoring its wildness.
But before we look to the future, Chapter 2, “Digging into the Past,” will take us back to the very beginnings of time and the great adventure of existence.
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Time is God’s way of keeping everything from happening at once.
ANONYMOUS
THERE IS AN unseen dimension to the far-and-away spread of the prairies, and that dimension is time. At first glance, one might mistake this for a place that time and change have somehow overlooked. These level plains and soft, rolling hills seem to have settled here quietly, their surface unmarred by signs of geological strife. But appearances can be deceiving. The great grasslands of central North America have been shaped over the past three or four billion years by the same forces that raised the Rockies and excavated the Grand Canyon. Their surface has been seared by the sun, scoured by ice, blasted by blowing sand, and buried in deep drifts of gravel. As a result of immense energies beneath the surface of the Earth, the plains have been raised up, forced down, drowned by oceans, and blanketed in ash. They have experienced every shudder and wrench as continents have collided and torn away from each other, only to collide and tear away again.
The traces left on the surface of the prairies by this planetary bump and grind are surprisingly minimal. Yet if you know what to look for and where to look for it, the subtleties of the prairie landscape become eloquent. An oil well bears witness to ancient tropical seas. A vast level plain provides an unexpected reminder of the protracted violence of mountain building. A hummocky wheat field speaks of the lumbering passage of glaciers. To an observer with a little basic geological knowledge, even the most unspectacular prairie landscape suggests a long and spectacularly interesting history.
Under the Waves
Trilobite
To go back into the prairie’s history means to go down. The record and residue of times past lie beneath our feet, so wherever we go on the prairies, we are traveling across vanished worlds. Straight beneath you, for example, at a depth of between 2,000 and 4,000 miles (3,000 and 6,500 kilometers), lies the Earth’s core—the yolk of the planetary egg—which coalesced out of a whorl of star dust some 4.5 billion years ago. This partly solid, partly fluid center is encased in an equally ancient layer of rock called the mantle. And surrounding the mantle is a covering of waxlike malleable material known as the asthenosphere, which is kept at a lethargic boil by the heat of its own radioactive decay. As the source of the molten magma that periodically shoots up through volcanic fissures and rifts in the ocean floor, the asthenosphere is the main powerhouse of geological turmoil.
The roiling-and-toiling asthenosphere occupies a zone between about 45 and 150 miles (70 and 250 kilometers) below the surface. Between it and us lies a relatively thin and fragile shell of rock, known as the lithosphere. The outermost membrane of this rocky shell is the Earth’s crust, a layer that is thinner, proportionately speaking, than the skin