Colonizes disturbed sites including burns. Tussock communities are stable for many decades, but are eventually replaced in the absence of disturbance. Flower buds are formed the year prior to flowering. Survives fire because its growing points are insulated by tightly bunched dead and live tillers, stem sheaths, and scales. The elevated position of tussocks increases resistance to ground fire.
Fire provides an opportunity for seedling establishment.
Since sheathed cottonsedge has both shallowly and deeply buried seed, some viable seed is available regardless of depth of burn into the peat horizon. Burned peat is an ideal seedbed. Severe fire may kill tussocks Sheathed cottonsedge sprouts from burned tillers and establishes from seed following fire. Flower and tiller production increase after top-kill. Grazed by sheep, cattle, lemmings, ground squirrels, caribou, and geese.