The near extinction of the gray wolf across most of the West in the past century now appears to have removed the natural element of "fear" from these ecosystems.
It has triggered a cascade of ecological effects on everything from elk populations to beaver, birds, fish, and even stream systems and helped lead directly to the collapsing health of aspen and some other tree species and vegetation.
Two recent studies by forestry scientists from Oregon State University, published in the journals BioScience and Forest Ecology and Management, outline a role for the gray wolf that is complex and rarely understood, but helps explain many major problems facing western streams, forests and wildlife.
"It would appear that the loss of a keystone predator, the gray wolf, across vast areas of the American West may have set the stage for previously unrecognized and unappreciated ecological changes in riparian and upland plant communities, and the functions they provide," the scientists concluded.
The studies were authored by William Ripple, a professor, and Robert Beschta, a professor emeritus, in the OSU College of Forestry. In their research, the scientists explore a concept that has been called "the ecology of fear."
The ecological and historical significance of wolves is only partly due to the actual impact they have by preying on other animals, both large and small, the OSU researchers have found. Just as important is the fear that many larger animals have of wolves, and the resulting behavioral changes in elk and some other grazing animals.