gray wolves

In the northern part of Yellowstone National Park, an historically large bison herd is hampering the comeback of quaking aspen trees, whose numbers were greatly diminished by decades of over-browsing by elk. Restoring the balance of ecosystems at Yellowstone is proving to be a complicated matter.

Long ago, the bison population in the Great Plains was as much as 30 million. The population sharply decreased in the 1800s. By the 1830s, there were no bison east of the Mississippi River. Fifty years later, the Plains bison was nearly extinct. Several small herds lived near Yellowstone Park when it was established in 1872, but poachers killed off nearly of them by the turn of the century. Protective measures were taken and by 1925, Yellowstone’s Lamar Valley herd had grown to more than 750. After that, occasional culling took place for over 40 years.

When gray wolves and cougars were removed from the park, elk populations boomed, and the elk gradually decimated the growth of quaking aspen, cottonwood, willow, and berry-producing shrubs. Both elk and bison were regularly culled until 1968 when public and congressional outcry intervened.

The return of wolves and cougars to the park made some progress in restoring ecosystem balance, particularly with respect to the elk population which has dropped from 20,000 to 5,000. But bison numbers have grown to over 4,000 over past 20 years and the damage once caused by elk is now continuing from bison.

Park administrators are faced with complex management decisions about how to best preserve the ecosystems at Yellowstone National Park.

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Bison in northern Yellowstone proving to be too much of a good thing

Photo, posted October 6, 2016, courtesy of Christian Collins via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Oregon State University scientists have proposed a series of management changes for western federal lands aimed at re-establishing ecosystems there. Their proposal would result in more gray wolves and beavers in nearly 200,000 square miles of federal lands in 11 states.

In each of those states, the researchers identified areas containing prime wolf habitat. Gray wolves were hunted to near extinction in the West but have been gradually reintroduced in some areas starting in the 1990s. Wolf restoration offers significant ecological benefits by helping to naturally control the population of grazing animals such as elk. This in turn facilitates the regrowth of vegetation species such as aspen, which ultimately supports diverse plant and animal communities.

Beaver populations, which used to be robust across the West, declined roughly 90% after settler colonialism and are now nonexistent in many areas. By felling trees and shrubs and constructing dams, beavers enrich fish habitat, increase water and settlement retention, maintain water flows during droughts, and increase carbon sequestration.

According to the researchers, the biggest threat to these western lands is livestock grazing, which has degraded ecosystems to a great extent. They recommend the removal of grazing on about 30% of the federal lands being used for that purpose and instead would have rewilding efforts go on.

The American West is going through a period of converging crises including extended drought and water scarcity, extreme heat waves, massive fires, and loss of biodiversity. Rewilding is a way to reestablish long-standing ecosystems.

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More wolves, beavers needed as part of improving western United States habitats, scientists say

Photo, posted October 1, 2020, courtesy of Tina DaPuglet via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Too Many Bison | Earth Wise

In the northern part of Yellowstone National Park, an historically large bison herd is hampering the comeback of quaking aspen trees, whose numbers were greatly diminished by decades of over-browsing by elk. Restoring the balance of ecosystems at Yellowstone is proving to be a complicated matter.

Web Links

Rewilding The American West | Earth Wise

Oregon State University scientists have proposed a series of management changes for western federal lands aimed at re-establishing ecosystems there. Their proposal would result in more gray wolves and beavers in nearly 200,000 square miles of federal lands in 11 states.

Web Links