Clearing and the erosion that sometimes followed were relatively local and distinct effects of settlement. Uses of uncleared forest land had widespread, but more subtle, effects. Selected white pines and yellow-poplars were cut for lumber; oaks for shingles; and hickories mostly for firewood. Other species were put to less important, miscellaneous uses. Many plants were collected for food and dyes or for medicinal purposes. Ginseng, which has a forked root highly prized in China for its supposed medicinal and aphrodisiac values, was nearly eliminated by eager “sang” diggers who sold the roots for export. Probably even more pervasive was the influence of livestock. Hogs, and sometimes cattle and sheep, were allowed to roam the forests, grazing, browsing, and rooting for a living. Mast—acorns, chestnuts, and beechnuts—formed an important part of the diet of hogs, but these omnivorous creatures ate all sorts of plants and small animals. As anyone knows who has observed a grazed woodlot, livestock can quickly impoverish the ground and shrub layers of a forest. Grazing and browsing, along with use of fire, prevented the return of forest to the grass balds. All these uses of the forest undoubtedly changed the proportions of many tree and lesser plant species in the total forest composition. Precisely how much they did so cannot now be determined. The impact of settlement on certain wildlife species is more easily seen. Elk disappeared about the time the earliest pioneers moved in. The beaver, an easily trapped animal, was nearly gone by the end of the 19th century. Wolves and cougars, hunted because they sometimes killed livestock—and uncomfortable in the presence of people—followed soon after. Deer, bear, and turkey persisted but in much-reduced numbers, with the bears retreating to rough, wild country in the central heights. Smaller animals fared better, although such hunted species as raccoon, opossum, and gray squirrel perhaps suffered some reduction. About 1900 a new era began, bringing the greatest shock yet to Great Smokies ecosystems. Large lumber companies, having logged off the big timber of New England and the Great lakes states, turned their attention to the virgin stands of the Southern Appalachians. Setting up sawmills at the fringes of the mountains, they rapidly worked their way up the coves, just as Cherokees and settlers had done before them. Railroads, built to carry logs to the mills, were extended upstream as cutting progressed. In some watersheds, such as those of the Little River, Big Creek, and the Oconaluftee, nearly all species of trees were taken. In others, such as Abrams Creek, West Prong of the Little Pigeon, and Cataloochee, cutting was selective. By the late 1920s, logging, added to settlement practices, had at least partially cleared more than 60 percent of the land in the Great Smoky Mountains.