Yellowstone National Park in Wyoming used to have an issue with deer overrunning the vegetation. They would consume the wild saplings that were supposed to populate the forest with beautiful trees, but instead would never see growth past a foot or two.
Unsure of how else to solve this problem without introducing more unnatural and potentially harmful substances to the natural ecosystem, scientists decided that it would be beneficial to reintroduce wolves to the park which had been previously removed.
The effects happened immediately—the deer that populated the area congregated in places where they were less likely to be trapped by the wolves. This freed up a lot of land for vegetation to begin to flourish.
The trees weren't the only things that changed. A huge domino effect caused an increase in other animal populations and improved the rivers' abilities to resist erosion because of the strong roots of the newly birthed trees.
