A new study has revealed a remarkable ecological recovery in Yellowstone National Park, as aspen trees begin to thrive once again – thanks largely to the return of wolves.
Wolves were lost from Yellowstone in the 1920s due to hunting, habitat loss and government eradication schemes. Decades passed without these natural predators on the land, seeing Rocky Mountain elk (Cervus canadensis) populations soar. These large herbivores heavily browsed young quaking aspen (Populus tremuloides) saplings, preventing the growth of mature trees.
Following the 1995–96 reintroduction of wolves to park, things slowly started to change – and now, 30 years on, the first wave of new overstory aspen in 80 years has been recorded.
The study, published in the journal Forest Ecology and Management, focused on Yellowstone’s northern range and found that roughly a third of the 87 aspen stands surveyed were full of tall, healthy saplings – a sharp contrast to the 1990s, when young aspen were nearly non-existent.
Another third of the stands had patches of tall saplings beginning to grow into mature trees, while the remaining areas are still struggling under heavy browsing, mostly from elk and an increasing number of bison.
- “I moved to remote cabins in Yellowstone and learned to speak with the wolves – this is what they’ve taught me”
- These intimate photographs capture the stunning beauty of wild wolves
- Wolf vs dog: what's the difference between man's best friend and its wild cousin?
- Coastal wolf found dead in lair on Alaskan island – dissection reveals curious thing that caused it
“The reintroduction of large carnivores has initiated a recovery process that had been shut down for decades,” says lead author Luke Painter from Oregon State University (OSU).
The research team believes this change is an example of a trophic cascade – where a shift at the top of the food chain, such as the reintroduction of predators, ripples through the ecosystem. Wolves, along with bears and cougars, have helped reduce elk numbers, giving aspen a chance to regrow.
“This is a remarkable case of ecological restoration,” Painter adds. “Wolf reintroduction is yielding long-term ecological changes contributing to increased biodiversity and habitat diversity.”
While the recovery is not uniform across the park, the researchers say the findings offer a hopeful sign that restoring natural predator-prey relationships can help bring ecosystems back into balance.
- What wildlife can I see in Yellowstone National Park, USA?
- These are the 10 best scenic drives for wildlife lovers in US national parks
Top image: wolf in Yellowstone. Credit: Getty
More amazing wildlife stories from around the UK
- "I didn’t know what I was looking at": drone films one of Earth's rarest and weirdest animals
- Its top speed is 50 miles per hour, it's constantly on the move and takes part in one of the greatest spectacles on the planet
- This Californian waterway was a polluted wasteland –then the sea otters arrived
- Scientists hid 956 camera traps across the Himalayas, sprayed them with perfume and waited...
