“ECOLOGICAL LAND CLASSIFICATION” is an attempt to see beyond the human impacts of the last few centuries and uncover the enduring components of the environment (climate, soils, landforms, vegetation, and so on) that make one part of the world biologically different from the next. While we cannot go back in time and view the wild prairies in full bloom, we still have a chance to identify and assess the fundamental factors that define them.
Over the last decade, the ecological regions of the Great Plains have been mapped in different ways by different agencies, whether in broad strokes as part of continentwide research or more minutely, state by state and province by province. One result of this effort is a set of maps created under the joint authorship of the World Wildlife Fund Canada and its counterpart in the United States, the WWF–U.S. Seen through the lens of these organizations, the Great Plains Grasslands come into focus as a mosaic of fifteen ecoregions. See Map 4: Ecoregions of the Great Plains.
For example, the Aspen Parkland ecoregion lies across the midriff of the Prairie provinces (Alberta, Saskatchewan, and Manitoba) and provides an interface between the boreal forest and the open plains. Rising in the north as a closed poplar woodland with occasional stands of spruce, it gradually unfolds into a rolling grassland dotted with aspen groves and dominated by various speargrasses, wheat-grasses, and most notably, fescues.
Rough fescue
Because of the predominance of fescues in the Aspen Parkland, the region is sometimes known as a fescue grassland. The same term is also applied, for the same reason, to the community of plants found in the Foothills Grasslands. Located on the undulating slopes at the foot of the Rocky Mountains, this ecoregion is dominated by rough fescue, together with lesser quantities of June grass, speargrass, wheatgrass, and various flowers and shrubs.
East of the foothills and south of the Aspen Parkland lie two ecoregions with subtly different characteristics. The Northern Mixed Grasslands take their name both from their northerly location and from their characteristic mixed-height cover of grasses. Here, the sparse, tufted vegetation of the foothills gives way to a groundcover of ankle-high grasses, notably blue grama, intermixed with an overarching canopy of knee-high stands, including various spear- and wheatgrasses. As this mixed grassland flows southward, the canopy of taller, midheight grasses gradually thins out, and the overall height of the vegetation diminishes. This transition from mixed- to short-grass prairie continues to the south in the Northwestern Short/Mixed Grasslands ecoregion.
The trend to shorter grasses culminates in the Southern Short Grasslands of the High Plains. Here, in an area once memorialized by Coronado as a land of “very small plants,” the vegetation is dominated by a ground-hugging mat of grama and buffalo grass. Yet here, too, there are subtle transitions. For if the grasslands diminish in height from north to south, they shoot up from west to east as they escape from the rain shadow of the Rockies. This trend is reflected in the shift from the short-grass prairies of the west, with their carpet of stunted plants, to the multilayered, knee-high vegetation of the Nebraska Sandhills and the Southern Mixed Grasslands.
On the eastern flank of the plains lies the tall-grass-prairie region, so named for the luxuriant stands of big bluestem and Indian grass that once flourished there. “The grass is so very high that a man is lost amongst it,” one early traveler reported from southern Wisconsin in 1761. Bright with brown-eyed susans and other flowers, these magnificent prairies extended from the Northern and Central Tall Grasslands south through the Flint Hills to the Blackland Prairies of east-central Texas. Many of the same species of grasses are also found, as an understory, in the juniper breaks of the Edwards Plateau Savannas and in the hickory-and-oak woodlands of the Cross Timbers Forest and the Southern Prairie-and-Oak Transition.
And finally, right out in the middle of everything, stand the lonely, displaced islands of ponderosa pine, white spruce, and paper birch that make up the Black Hills Coniferous Forest.
The ecological interactions that find expression in these varying landscapes have been at work for thousands of years. Even today, characteristics such as average temperatures, precipitation, length of growing season, and drainage patterns provide the physical framework or, one could say, the loom on which the fabric of the Great Plains ecosystem is woven. Yet for all their continuing importance, these long-term physical features are no longer the only powers in the land. Other interests have taken over; other hands are pulling threads. Those hands, of course, are human.
Over the last two hundred years, human beings have hit the prairies with the force of a major geological crisis, triggering not only extinctions and extirpations—of plains wolves, plains grizzlies, plains elk, plains bighorn sheep, free-ranging plains bison—but also dramatic shifts in the vegetation. Taken as a whole, the Great Plains Grasslands now rank as one of the most extensively altered ecosystems on Earth. There is scarcely a patch of ground where we have not left our footprints. The southernmost Short Grasslands, for instance, are as sun-frazzled and arid a country as you could ever expect to see, yet even there an estimated 27 percent of the ecoregion has been brought under cultivation. The surviving native prairie in the region is now devoted to livestock or converted to ranchettes, on the advancing front of urbanization. In the mixed grasslands, by contrast, the percentage of land under cultivation rises from 15 percent (in districts with scant precipitation) to over 96 percent (where conditions are most conducive to crop production). And in the tall grasslands, with their relatively generous climate and deep, black earth, fully 99 percent of the native grasses have been plowed under to make way for farming.
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. Last chance to see the Dakota skipper butterfly, the Colorado checkered whiptail lizard, Preble’s meadow jumping mouse, the black-footed ferret.
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 hot spots. (By comparison, the rain forests of northern California have a richness index of only 1,710, while the Everglades come in at 1,855.)
FIELD NOTES
Chimney Coulee, June 29: “Last night, we stood on a hillside, ankle-deep in prairie wool, and heard a quavering whisper that seemed to come out of nowhere. And again, like a sudden sigh. Finally we saw them, high above our heads, a pair of nighthawks that sometimes interrupted their insect-hunting maneuvers to plunge headlong down the sky and rasp the air with their wing feathers. In that moment, the whole place was shot with silver.”
Grasslands National Park, July 9: “In just two days we have seen meadowlarks, horned larks, Sprague’s pipits with their surprising pink feet, phalaropes spinning and dipping like wind-up birds in a dugout,
