Evolution: reintroduction shows econiche importance (Evolution)

by David Turell , Thursday, May 28, 2020, 20:01 (1423 days ago) @ David Turell

Same result. Wolves must be present as top predators:

https://phys.org/news/2020-05-reintroduction-wolves-tied-tall-willows.html

"The reintroduction of wolves into Yellowstone National Park is tied to the recovery of tall willows in the park, according to a new Oregon State University-led study.

"Wolves were reintroduced to the park in 1995. The new study shows their predation on elk is a major reason for an increase in the height of willows in northern Yellowstone, said Luke Painter, a wildlife ecologist at Oregon State University and lead author on the study.

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"'Our results demonstrate that the reduction of elk browsing over the last two decades in northern Yellowstone has allowed willows to grow taller in many places, despite a warming and drying climate," Painter said, adding that willows aren't recovering in some areas due to continued browsing by increased numbers of bison.

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"Painter and co-author Michael Tercek of Walking Shadow Ecology in Montana found a strong contrast between sites along streams compared to wet meadows. Willows in meadow sites did not increase in height, but willows in stream sites increased significantly, exceeding 200 centimeters, or 6 feet—a height accessible to elk—in the summers of 2001-04 and in the spring of 2016.

"They also found a significant change in willow thickets at least 200 centimeters in height along streams, with thickets occupying about 80% of willow patches in some sites, but as little as 22% in others. Tall willow thickets are an important habitat feature and an indicator of willow recovery, Painter said.

"Thus, passive restoration through the return of predators has begun to reverse the loss of willows, something active culling of elk in the past was unable to accomplish, he said.

"'Wolves didn't do it all by themselves," Painter said. "Other predators and hunters also affected elk, but this would not have happened without the wolves.

"'This does not mean a wider expanse of willow habitat has been restored as existed in the early days of the park when beavers created large wetland expanses. This may eventually happen as beavers return but could take a long time to develop."

"This is the latest OSU study led by Painter that examines the effects of wolf reintroduction to Yellowstone on trees. In 2018, he published a study that showed that aspen is recovering in areas around the park, as well as inside the park boundary."

Comment: Same view. Econiches are absolutely necessary for all of living organisms food supply. The vast diversity of the bush of life allows this to happen naturally, until humans step in to change things.