Prairie: A Natural History
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Extending from Alberta south to the Mississippi River, the prairies are among the largest ecosystems in North America. Until recently, they were also one of the richest and most magnificent natural grasslands in the world. Today, however, they are among the most altered environments on Earth. Nevertheless, Candace calls the prairies a landscape of hope-a place that has experienced the onslaught of modernization yet still inspires us with its splendor.
Throughout the book, spectacular full-color photographs and elegant black-and-white line drawings illustrate the beauty and diversity of the North American heartland. Both an authoritative reference and an easy-to-read guide, Prairie: A Natural History is a must for anyone who wants to know more about the dazzling natural variety of the prairies.
Others, including many grasses and wildflowers, attempt to evade drought by going dormant and retreating underground, where they linger on in the form of seeds, rhizomes, or tubers. But if some plants favor patient waiting, others put their faith in speed. Instead of trying to sit out the drought, they attempt to avoid it entirely. Take, for example, the prairie crocus, or pasque flower. An inexhaustible source of pleasure for people on the northern plains, crocuses appear on the trailing edge of winter as tight clusters of furry, pointed buds that push up through the dead grass like so many inquisitive snouts sniffing for spring air.
From up on the benches, you can see the descendant of this ancient flood, a soapy, sleepy little stream that writhes through its oversized course, as if trying to make up in complexity for what it has lost in force. High on the benchlands, the grasses are stunted and crisp, and the ground bristles with clumps of prickly pear cactus. At one time, long before the Ice Age, this drought-stricken upland was itself the course of a great river that flowed down from the young Rocky Mountains across the northern plains, burdened with loads of gravel and debris.
Although waterbears may set the outer limits of biological endurance, most soil microorganisms have an extraordinary ability to “play dead” for months or years. A nematode egg can lie in the soil for up to a decade, waiting for its preferred plant host to appear. The minute that conditions improve—for example, when a dry crumb of soil is moistened by long-awaited rain—the soil organisms come back to life and start to eat and reproduce at a hectic rate. Life occurs in manic pulses—wet, on; dry, off—typically with peaks in the spring and autumn, and lulls in the hot summer months.
Soon, silvery swarms of insects were moving east on the prevailing winds, rising to heights of 6,000 to 10,000 feet (2,000 to 3,000 meters) and sweeping across large distances in a matter of hours. (Grasshopper Glacier, in the Beartooth Mountains of Montana, contains the remains of several million locusts that became embedded in the ice sometime in the distant past, probably when one of these migrating swarms was brought down by turbulence. ) Because the insects could not sustain themselves for long away from their usual range, these eruptions generally ended within a year or two at the most.
The same small patch of prairie soil that is hopping with springtails may simultaneously be home to up to 60,000 mites, representing dozens, or even hundreds, of species. (Although 48,000 kinds of mites have so far been identified around the world, the final catalog of species is expected to reach half a million or more. ) While many mites make their living peaceably by feeding on microbes and plant roots, others are voracious predators—the tigers of this invisible world. Spinibdella cronini, for example, is a largish red mite (about the size of the period at the end of this sentence) that is common in prairie soils and that preys on soft-bodied mites and springtails.