A wanderer in Nebraska or Kansas today who was given to evocative metaphor would most likely need an especially vivid imagination, not only to produce the metaphor but even to imagine the prairie. Very little of this uniquely North American landscape remains, especially the tallgrass prairie that is Heat-Moon's subject and that helped make up the mixed grass prairie that loomed so large in the lives of Cather's characters.

Prairie once covered 140 million acres, from Saskatchewan to Texas, the Rocky Mountains to Indiana. Shortgrass dominated in the west, where there was least rain; tallgrass in the east, where it was wettest; and mixed grass in between, where the dominant grasses varied from place to place according to climate and other local factors. The tallest grasses averaged about six feet but grew to as much as ten; Heat-Moon says "red men once stood atop their horses to see twenty yards ahead."1 Tallgrass produced the deepest and most fertile soil; but it was this very quality that led to its demise when settlers plowed nearly all of it up in the second half of the 19th century for cropland. Today only some 4% of the original extent of tallgrass remains, essentially none of it in Nebraska; the area around Red Cloud, where Cather lived, has all been plowed for agriculture.

A significant parcel still exists in eastern Kansas in the Flint Hills, Heat-Moon's subject. The presence of flint, or chert, in the soil there made the area unsuitable for plowing, and it was left for ranchland, with cattle replacing bison in the landscape. The primary grasses here are big bluestem, little bluestem, switch grass, and Indian grass, though there are dozens of others plus hundreds of species of forbs (non-woody flowering plants, including those we think of as wildflowers). Indeed, diversity is one of the most salient features of the prairie, and one of the secrets of its persistence.

As tall as the grasses may be aboveground, by far the greatest portion of their biomass – 75-80% – grows underground, where it is protected from the legendary freezing and drought of the prairies, as well as fire, trampling, and grazing. The leafy portion that emerges aboveground performs photosynthesis for the plant, while beneath the surface long horizontally-growing stems (rhizomes) and roots extend many feet into the soil, accessing deep stores of water that are unavailable to non-native plants that lack this apparatus. From this massive tangle of soil and biomass the settlers cut the sod bricks with which they built their houses, as trees were exceedingly scarce and grew only in the stream bottoms.

Periodic fire is essential to prairie health. It clears away the voluminous dead material on the surface so the sun can warm the ground in the spring and the new growth can reach the sunlight. It also promotes the decay and recycling of nutrients. Fire is most often caused by lightning strikes, although Native peoples also started fires to encourage new growth and to herd bison. In later years the new settlers and their descendants suppressed fire, which impaired the health of the prairie grasses and allowed the invasion of trees and shrubs. These then created shade and further reduced the amount of sunlight on the grasses. Ultimately even many portions of the prairie that were not plowed up or built on became badly degraded and covered with brush. Eventual prairie restoration efforts didn't succeed until the important role of fire was understood.

Bison, too, were an important factor in maintaining prairie health. Grazing served some of the same functions as fire, reducing the amount of dead material covering the ground and encouraging growth by cropping off the shoots. It's estimated that in the mid-19th century bison numbered between 30 and 60 million,2 along with vast numbers of elk, deer, and antelope, all contributing to the well-being of the prairie. The cattle that later replaced them had different grazing habits, which tended to reduce the prairie's diversity and generally degrade its quality and resilience.3

A movement developed late in the 20th century to formally protect the remaining significant parcels of tallgrass prairie, as well as to restore smaller parcels wherever possible. This resulted in the establishment of the Tallgrass Prairie Preserve in northeastern Oklahoma, the southern extension of the Flint Hills and the largest remaining parcel of the original tallgrass prairie, which has been owned and managed by The Nature Conservancy since 1989; and the nation's first federally protected prairie, the Tallgrass National Prairie Preserve, in the northern Flint Hills of Kansas, in 1996. Bison have been reintroduced to both sites, where they have thrived and now number in the thousands. They are a major draw for tourists, along with dozens of species of increasingly scarce birds such as the sandhill crane, the prairie chicken, the whooping crane, and the burrowing owl, and dozens of species of butterflies.

Restoration projects have been spearheaded by a broad array of organizations and consortiums. The Nature Conservancy has been involved with many projects, including Glacial Ridge National Wildlife Refuge in Minnesota, the largest prairie restoration project to date, which required the participation of many additional agencies to bring it about. The Fermilab particle accelerator in Batavia, Illinois is the site of an unusual project that began with the restoration of the 1.24-square-mile area in the center of the accelerator ring, carried out by Fermilab employees under the leadership of a biologist. The U.S. Forest Service operates the Midewin National Tallgrass Prairie on the grounds of the former Army Ammunition Plant near Joliet, Illinois (see images above). Other projects continue to proliferate.

More recently, prairie restoration has been the subject of interest from another quarter. Prairie grasses turn out to be by far the most efficient absorbers of carbon of any form of vegetation, far superior to crops, which don't store carbon in soil, or even trees, which grow much more slowly.4 And they maintain the underground carbon sequestration for thousands of years while the aboveground portion may be harvested as an alternative fuel, one that is more efficient than those currently in widespread use.5 Moreover, these grasses don't require chemical fertilizers or pesticides, and can be grown on marginal cropland and brownfields, so they don't take land away from food crop production.

This approach to greenhouse gas reduction would require massive restoration efforts, necessitating a good deal of work on improving reconstruction methods and grassland management. But should this plan gain enough traction with policymakers, we could once again begin to see a landscape where grasses are indeed reborn, and seem again to gallop like the bison.

1 Heat-Moon, William Least. PrairyErth (a deep map). New York: Houghton Mifflin/Mariner, 1991, p. 12.

2 Wildlife Conservation Society. "Bison." http://www.wcs.org/saving-wildlife/hoofed-mammals/bison.aspx

3 Harrod, Jay. "Bison Round-Up at Tallgrass Prairie Preserve." The Nature Conservancy: Oklahoma. http://www.nature.org/wherewework/northamerica/states/oklahoma/features/

4 Morris, Geoffrey. "Prairie reconstruction for carbon sequestration and biomass production: A genomics approach for harnessing the benefits of genetic variation and local adaptation." The University of Chicago: Borevitz Lab. http://borevitzlab.uchicago.edu/Members/gmorris/proposals/argonne-proposal/?searchterm=carbon%20sequestration

5 Tilman D, Hill J, & Lehman C. "Carbon-negative biofuels from low-input high-diversity grassland biomass." Science 314: 1598-1600. Dec 8 2006.