W. North America, Alaska to S. Calif.
"Several mammals eat western swordfern, including elk, black-tailed deer, mountain beavers, American black bears (review by), and mountain goats. Western swordfern communities also provide habitat for several bird species (e.g.,, Table 13). Western swordfern was apparently not eaten by domestic sheep in a Douglas-fir plantation in the Oregon Coast Ranges. However, another study in coastal Douglas-fir plantations found that domestic sheep consumed a lot of ferns, although it was unclear how much of their forage consisted of western swordfern.
A review suggests that American black bears sometimes forage on western swordfern, and a study from Olympic National Park identified western swordfern in mountain goat fecal pellets collected in late winter or spring. However, most information regarding wildlife use of western swordfern concerns elk, black-tailed deer, and mountain beaver.
Western swordfern is an important elk food in Douglas-fir forests and other habitats in Oregon and Washington. Jenkins and Starkey provide a summary of Roosevelt elk use of western swordfern throughout the Pacific Northwest. The elk consumed an abundance of ferns, including western swordfern, during winter and spring. On the Olympic Peninsula, western swordfern is seasonally important for elk. Western swordfern was one of the 10 most frequently used elk foods in the southern Oregon Coast Ranges, and the western swordfern-redwood-sorrel habitat type provided much of the food for elk in both clearcuts and undisturbed forests.
Western swordfern is a moderately important food for black-tailed deer year-round. Western swordfern made up 13% of the annual diet of black-tailed deer at one site (review), and was found in 27 of the 178 stomach samples from black-tailed deer in western Washington. Western swordfern was among the most common species browsed by mule deer in the western hemlock/salal/western swordfern and the Pacific silver fir/western swordfern-redwood-sorrel associations on the Olympic National Forest. Deer sign was frequently observed, and recent activity was noted in late summer. Klein observed heavy spring use of western swordfern by mule deer on Coronation Island in southeast Alaska, despite its apparent low palatability.
Western swordfern is an important plant in mountain beaver habitat from British Columbia to California, providing both food and cover. Mountain beavers as young as 7 weeks old eat western swordfern. Mountain beaver may be abundant in western swordfern sites in western Oregon, where western swordfern is an important winter food. Western swordfern is a favorite mountain beaver food on the Siuslaw National Forest, and mountain beaver populations may be especially large in the moist stands of the western hemlock/Pacific rhododendron/western swordfern association.
Western swordfern communities provide habitat for several species of birds. In the Sitka spruce and western hemlock zones on the Olympic Peninsula and in the North Cascade Range, western swordfern is an understory dominant in old-growth forests providing northern spotted owl habitat. In western Washington, it is among the dominant understory species in second-growth Douglas-fir forests (after logging and fire) that serve as drumming sites for Pacific ruffed grouse. The 2 dominant species of ground vegetation at drumming sites are western swordfern and salmonberry (the abundance of one correlates with the scarcity of the other). Ruffed grouse select drumming logs that are higher than surrounding growth of western swordfern. A census in coniferous forests of the central Oregon Cascade Range showed that several species of birds used the 3 habitats shown in Table 13, which all contain substantial western swordfern cover." 
"American Indians used western swordfern for a variety of purposes, including household tasks and applications, food, and medicine. Northwest coastal peoples used western swordfern leaves to line pits for cooking, to layer between food in baskets, drying racks, and storage boxes, and to cover floors and beds. Western swordfern leaves were used in a traditional game known as pala-pala. The species also played a part in Kwakiut'l mythology and so was used in rituals. The large, basal clump of leaves and the rhizomes of western swordfern were used as food by several tribes. They were roasted or steamed, peeled, and eaten
Traditional medicinal uses of western swordfern include rhizomes eaten to cure diarrhea, young leaves chewed and swallowed for sore throat or tonsillitis, an infusion of boiled rhizome used on sores and to ease pain, and a tea from boiled stems used in labor. Aerial parts of western swordfern are used to stimulate digestion in ruminants." 
"Commercial harvesting of floral greens, including western swordfern, began in 1915 and remains one of the most enduring and stable year-round nontimber forest products industries in the Pacific Northwest. Enormous quantities of western swordfern leaves are gathered for backgrounds in floral displays; the evergreen leaves keep well in cold storage and are even exported to Europe. Western swordfern requires partial shade to grow in forms acceptable for commercial harvest (with deep green, broad, spreading leaves). See Table 5 for information on which forest zones have the greatest potential for western swordfern production.
Western swordfern is used extensively for landscaping." 
 Zouhar, Kris. 2015. Polystichum munitum, western swordfern. In: Fire Effects Information System,. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us /database/feis/plants/fern/polmun/all.html