Yellowstone's wolves are helping a new generation of young aspen trees to grow tall and join the forest canopy — the first new generation of such trees in Yellowstone's northern range in 80 years.
Gray wolves (Canis lupus) had disappeared from Yellowstone National Park by 1930 following extensive habitat loss, human hunting and government eradication programs. Without these top predators, populations of elk (Cervus canadensis) grew unfettered. At their peak population, an estimated 18,000 elk ranged across the park, chomping on grasses and shrubs as well as the leaves, twigs and bark of trees like quaking aspen (Populus tremuloides). This stopped saplings from establishing themselves, and surveys in the 1990s found no aspen saplings.
