Soils are mostly deep, well drained, with loam and clay, supporting cool-season grasses, forbs, and shrubs. Dominant plant species of the High Plains include blue grama and green needle grass (bunch grasses), and buffalo grass and western wheatgrass (sod grasses). Their root systems make up 90 percent of the plant's mass.

A square meter of short-grass prairie can contain 12 or more plant species. In addition to grasses, the High Plains contain cushion plants, mat plants, and forbs. Cushion plants, like moss, also have large root systems that allow them to attach to rocky escarpments. Mat plants, such as sandwort, send their roots out in front of them. These compact plants have beautiful, fragile flowers that turn escarpments into natural rock gardens when they bloom. Forbs are herbaceous plants that grow less abundantly on the short-grass prairie, but have beautiful flowers that transform the prairie in times of adequate rainfall. Forbs are the dominant food sources for deer and pronghorn antelope.

Most prairie plants are dormant during the extremes of summer heat and winter cold, growing only in late spring or early summer and again in the fall. This plant survival mechanism allows the High Plains to support the many forms of wildlife and insects that eat, nest, or hide in the plants

The Prairie Dog Ecosystem
Early explorers of the High Plains referred to the dominant burrowing animal of the ecosystem as wild dogs of the prairie or the "prairy dog," because of the barking sound they make. These small rodents provide the anchor for vast plains ecosystems that are dependent on the complex systems of underground burrows the prairie dogs construct. This system of tunnels creates prairie dog "towns" or colonies teeming with a diversity of life. For example, prairie dogs churn up dirt, mixing topsoil with underlying soils, making it easier for forbs to propagate. Birds often congregate in and around the towns, attracted by the insects that are easily seen in the patches grazed by the prairie dogs. Larger animals such as deer and pronghorn antelope prefer to feed in prairie dog towns because they like the easily digested forbs and herbaceous plants that grow in the colonies. Some animal populations, such as burrowing owls and swift foxes, are actually declining in part because of the decline in prairie dog towns. The black-footed ferret, also dependent on prairie dog towns, declined to the point of near-extinction. For more information on the black-footed ferret and other animals that depend on the prairie dog ecosystem, see the Activity 1 & Activity 2 page.

Energy Source for the Nation
The High Plains is a major source of coal, oil, gas, and uranium for the nation. For example, the Powder River Basin in northeastern Wyoming and southeastern Montana is home to the largest low-sulfur coal reserves in the United States. (Low-sulfur coal burns cleaner than the high-sulfur coal found in the eastern United States.) The coal in the Powder River Basin is found in thick seams—horizontal layers of solid coal running for kilometers beneath the Earth's surface. Some of these seams are 30 m thick and close to the surface, so the coal can be mined at the surface without going underground. As a result, huge quantities of low-cost, high-quality coal can be shipped by rail to 24 states to generate electricity. Over half of the electricity in the United States comes from coal-fired power plants. In 1995, 24 Powder River Basin mines produced 286 million tons of coal.

Clinker
The reddish siltstone rock that caps many ridges and buttes in the Powder River Basin is called "clinker" or "scoria." Clinker is rock that has been fused by the natural burning of underlying coal beds. Its red color is due to the oxidation, or rusting, of iron in the rock. The clinker, which covers about 4,200 km² of the basin, was formed by the burning of some 27 to 54 billion metric tons of coal within the past three million years. Some coal still burns today, sparked by range fires or spontaneous combustion.

Clinker forms a distinct part of the ecosystem in the basin. Because soils formed from clinker are very permeable, they absorb rain and melting snow like a sponge and protect it from evaporation. Plants such as ponderosa pine and skunkbush sumac grow on clinker because of this stored water. Deer and elk herds graze over it, and some springs that emerge at the base of the clinker have water quality good enough to support trout.

Management Challenges
In addition to the challenges inherent in living in a harsh environment, the people of the High Plains face a number of management challenges to keep the land healthy and productive. Water is scarce; many riparian (streamside) areas are becoming depleted; and in some areas, native grasses are being crowded out by invasive weeds. Local communities are changing farming and ranching practices to address these challenges. For example, ranchers and other land managers are turning to new rotational or seasonal grazing practices to help protect sensitive riparian areas. They are stepping up efforts to control invasive weed species, and they are using carefully controlled fires to replace the natural cycles of disturbance once provided by natural fire and bison. (Fire and bison both keep the grasses clipped, lowering vegetative buildup. In addition, fire and bison manure add nitrogen to the soils, producing nitrogen-rich grasses.)

Water Resources
Water, the lifeblood of the land, has always been a limiting factor in the settlement of the High Plains. The early farmer had a hard time coaxing crops from the plains until the windmill was used to harvest water from aquifers below the ground's surface. Approximately 90 percent of the water pumped from the Ogallala Aquifer is used for irrigation. Precipitation and surface streams replenish the aquifer, but surface streams in the arid High Plains are sparse and many are ephemeral, wet only at certain times of the year. Because of the heavy demand for water and the slow replenishment rate, the average water level of the aquifer declined nearly 3 m between 1940 and 1980, then another 30 cm in the 1980s. Better water management and new technologies have helped to slow this depletion. However, greater efforts will be needed to ensure that the water levels in the aquifer stabilize.

Grazing
Before the High Plains were settled, bison and other wild herbivores grazed the prairies. Eventually, as settlers moved in, these native roamers had to compete with cattle and sheep. Early settlers often grazed too many sheep or cattle for too long a period in one place. Thus, overgrazing was very common at the turn of the century. Although management practices have steadily improved since then, overgrazing still causes serious problems in many areas. Where public rangelands are involved, Resource Advisory Councils provide opportunities for a wide range of interests at the state and community level to have a voice in the management of grazing practices. Through a collaborative decision-making process, these councils are playing a critical role in developing guidelines for ecological grazing on public rangelands.

Riparian Areas
Riparian areas are the green, vegetated areas that border streams and rivers in the otherwise arid and semi-arid West. The condition of these critical areas in much of the western United States has been poor throughout much of this century. In the High Plains, rivers and streams are not abundant, and the productive areas surrounding them are often fragile and extremely important to sustaining healthy populations of fish, wildlife, and plants. Yet, concentrations of cattle and sheep in riparian areas and lower water levels have put stress on the ecological integrity of these streams. Declining conditions in riparian areas in some parts of the High Plains also have contributed to the decline of rare moisture-loving plants such as the Ute Lady's Tresses, a threatened orchid found along streams or where mountains begin at the western edge of the plains. This delicate plant requires specific moisture, sunlight, and temperature levels to thrive. Public and private land managers are beginning to assess and improve the condition of riparian areas and are implementing conservation measures through cooperative efforts with local ranchers and others.

Fire Cycles
Fire has played a part in the prairie ecosystem for thousands ofyears. Fires are ignited naturally by lightning. Native Americans also learned to set fires to promote new growth of grasses or to drive wildlife for hunting purposes. Grassland ecosystems depend on fire to recycle carbon and nutrients into the soil and to influence plant composition. But fire suppression efforts since the early 1900s have changed the composition of many grassland communities, an example of how single-purpose management techniques, however well intentioned, can degrade natural systems. Controlled fires can improve the quality of grasslands by removing buildup of vegetative litter, warming soil temperatures, and assisting seed germination.

Some fires that were once suppressed are now allowed to burn as part of a natural cycle within forest and grassland ecosystems. In remote areas, some agencies allow wild land fires to burn where there is an approved plan, as long as the fires remain within "prescribed" limits. However, wildfires are still aggressively fought near populated areas.

As more and more communities recognize the importance of fire to a healthy grassland ecosystem, prescribed fires are used increasingly as a management tool. Prescribed burns are planned and initiated by qualified professionals who are trained in using fire for resource management. Before any prescribed fires, burn plans must be approved. These plans must specify the objectives of the fire; location, size, and type of fire; how the fire will be started and controlled; how the smoke from the fire will be managed; and how the fire will be monitored and evaluated.

Weeds
Invasive weeds pose another threat to the High Plains ecosystem. These harmful and aggressive plants form monocultures (where one species replaces a diversity of species), reduce wildlife habitat, and degrade streams and ponds by displacing native grasses and plants that protect and hold the soil in place.
Weeds also greatly reduce the productivity of rangelands, affecting local economies throughout the High Plains. For example, leafy spurge, a very aggressive invasive weed, costs North Dakota about $75 million a year in damages due to lost livestock and agricultural production. Leafy spurge takes over rangelands and croplands. It reduces available forage and also is an irritant to the mouth and digestive tract, making some cattle sick.