New Science for a Classic Hall: Salmon and Bears Nurture Ecosystem Together
by AMNH on
After more than a year of restoration work, the classic habitat dioramas in the Hall of North American Mammals seem more vibrant and realistic than ever. While the diorama scenes haven’t changed, decades of scientific research and discovery are offering new insight into the stories they tell. Below, the last in a series of posts on new science behind the hall, this one on the diorama of the Alaska brown bear, found at the heart of the Hall of North American Mammals.
New scientific frameworks that have emerged since the Hall of North American Mammals first opened in 1942 offer new lenses through which to consider the dioramas’ carefully recorded scenes, including that of the Alaska brown bear diorama. One major shift has been the rise of ecology: the view of habitats as interconnected, self-regulating systems. Naturalists including Charles Darwin had recognized closely woven relationships in nature for centuries, but ecology became a dominant paradigm for studying nature only in the mid-20th century.
This discipline adds another dimension to this iconic diorama, in which two giant bears lumber toward a salmon after scaring off the original predator, an otter who scowls in disappointment.
The bears and salmon sit at the helm of the hall much as they do in their native ecosystems. Together, they are commonly identified as “keystone species,” organisms that have a disproportionately large effect on the surrounding habitat: take the top out, and like a stone archway, the whole thing falls apart.
On the West Coast, bears bolster the biomass of forests by consuming sockeye salmon that swim upriver each year. Salmon tissue is rich with nitrogen, which the fish bring from the ocean back to the freshwater rivers where they were born before spawning and dying. As bears scatter salmon carcasses and their own nutrient-rich scat through nearby forests, that nitrogen enters the soil and boosts trees’ growth
The more nitrogen in the tree leaves, the more those leaves enrich the streams they fall into, providing habitat for the next generation of salmon—and then the whole cycle starts anew.
A version of this story appeared in the Fall 2012 issue of Rotunda, the Member magazine. Become a Member.