Erosion often happens when plant roots are too shallow to hold soil. On grasslands, short roots occur mainly due to

• Overgrazing -- plants are grazed too often.
• Overrest -- grazing-dependent plants are grazed and trampled too seldom. Overrest is a problem mainly in brittle (seasonally dry) environments.
• A shift from perennials to annuals when management favors annuals. Perennials generally have much deeper roots.

This brittle grassland was damaged by overrest. It has had no livestock or significant concentrations of grazing animals on it since a nearby freeway interchange was built in the 1970s. Near Pendleton in northeastern Oregon, U.S.A.

More about brittle environments.