National Bison Range Wildlife Refuge
Mountain-Prairie Region

Grassland Habitat

Bison Graze in the grassesThough grasslands appear as wasteland, they form a rich ecosystem of specially adapted plants and animals. The grasslands of the National Bison Range are native Palouse Prairie. The primary grasses here are Idaho Fescue, Rough Fescue, and Bluebunch Wheatgrass. These native bunch grasses grow in clumps with the crown shading their roots. They are specially adapted to dry land conditions. While most plants grow from the tips of their branches or stems, the growth area of these grasses is at the base of the stem so that they can continue to grow after their tops have been grazed off.

Grasses are well adapted to the harsh, unsheltered environment of the open prairie which ranges from driving, icy blast of winter to the oppressive heat and searing wind of summer. Leaves die back and the dense crown protects the root in winter. In the summer the long slender vertical leaves present less surface to the sun's rays and prevent overheating.

Palouse Prairie grasslands also contain other broader leaved plants called forbs, usually noted as wildflowers, which also have defenses against the weather extremes. Many are perennials and winter under the snow as tiny flat rosettes of green leaves. In summer their leaves are small, have deep indented margins to minimize their surface, or curl to reflect the heat. Some are covered with insulating hairs.

The grassland ecosystem is completed with native grazers such as bison and pronghorn and a variety of birds and rodents and predators like the coyote. Grassland birds are usually plentiful but consist of fewer species than would be found in wetter areas. The birds too, are specially adapted to this environment of extremes. Their backs are streaked so they can nest unseen on the ground in the shade of an overhanging grass clump. They can be seen defending their own patch of turf by singing from song perches, usually tall weeds, around their territorial boundaries.

Last updated: April 5, 2011