This plant, particularly sun sedge (C. inops subsp. heliophila), is a dominant species in a number of ecosystems, such as many grasslands. On the prairies of the northern Great Plains it is codominant with grasses such as western wheatgrass (Pascopyrum smithii) and other wheatgrasses, big bluestem (Andropogon gerardi) and other bluestems, needle-and-thread grass (Hesperostipa comata) and other needlegrasses, and/or blue grama (Bouteloua gracilis) and other gramas. It is common on the tallgrass prairies of Kansas alongside bluestems and prairie sandreed (Calamovilfa longifolia). It can be a dominant species in Rocky Mountain meadows, woodlands in Nebraska, the Black Hills of South Dakota and Wyoming, and the plains of Saskatchewan. It can be found in each stage of ecological succession on grasslands. It can colonize blowouts, anthills, and prairie dog towns.