The restoration of gray wolves in Yellowstone National Park has helped revive an aspen tree population unique to the region, a new study has found. Quaking aspen, one of the few deciduous tree species in the northern Rocky Mountain ecosystem, is once again thriving, after suffering severe decline during the 20th century, according to a new study. “This is a remarkable case of ecological restoration,” lead author, Luke Painter, at Oregon State University’s College of Agricultural Sciences, said. The decline in aspen growth occurred in tandem with a surge in Rocky Mountain elk, which had lost a key predator following the elimination of wolves from the region by 1930. …At the same time… aspen recovery hasn’t been uniform across northern Yellowstone — and the growth is subject to numerous potential threats including climate change and encroachment of coniferous trees, are possible such factors. And other herbivores have increased in the region.