Researchers measured the changes in the Yellowstone meadow plant community from 1997 to 2007, including a period of extended drought, and found that shrubs (such as sagebrush) that grow in the drier meadows increased, while flowering plants decreased in number.
The USFWS said wolf populations have exceeded biological recovery goals and are now thriving.
While it was feared the elk population would be at risk upon reintroduction, wolf numbers on Yellowstone’s northern range has grown to 84 and elk numbers have not declined appreciably.
The study conducted by forestry researchers supports a “trophic cascade” theory of ecological interdependence — extending to plants, animals, food chains and ecological zones.
It is believed that about 640,000 years ago (during the Pleistocene epoch), a massive volcano erupted, creating a caldera in the center of what is now Yellowstone National Park.