Wolves Helping Aspens?

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Wolves Helping Aspens?

Post by BlackWarrior » Mon Jan 02, 2012 1:17 am

Wolves helping Aspens? Apparently so!
After research and studies, the release of wolves in Yellowstone park has supposedly helped the growth of aspens! ^^
Fifteen years after the release of wolves into Yellowstone National Park, the predators’ impact on the elk population has helped aspens, willows and cottonwoods thrive, new research suggests.

Oregon State University researchers charted the growth of young aspens, willows and cottonwoods in the park’s northern range at various times since the 1995-96 reintroduction of wolves to see how many plants grew to a certain size and how many had been browsed by ungulates.

Yellowstone’s northern range elk population declined from 15,000 animals in the early 1990s to roughly 6,100 animals in 2010, partly due to wolf predation. During the same period, researchers found that aspen, willow and cottonwood were generally allowed to grow taller and thicker, and fewer trees showed signs of browsing.

Researchers also reviewed the literature on “woody browse” species and found that 12 of 13 field studies reported taller plants since wolves returned to the ecosystem. Two remote sensing studies showed increases in willow canopies, too.

The findings, which appeared Dec. 23 in the online version of the journal Biological Conservation, support earlier studies that showed wolves have improved habitat in the park.

The study was launched in 1997 in an attempt to understand why aspen trees were at the time declining in Yellowstone, said study coauthor William Ripple, an ecology professor at Oregon State University.

“There was no clear scientific answer,” he said. “The topic of predators and wolves was not on my radar.”

After coring aspen trees and counting tree rings, “we found that there was a major decline ... starting in the first half of the 20th century,” Ripple said. “Aspen continued its decline all the way up to our study period, in 1997. At that point, we looked at the records. We found that wolves were extirpated early on, and the last wolf was killed in 1926.”

Since wolves were returned in 1995 and ’96, Ripple and his colleagues formed a hypothesis that aspens and other plants would start growing again into tall trees.

Indeed, the percentage of aspen trees browsed in one habitat type — upland areas without logs —dropped from 84 percent to 24 percent from 2006 to 2010. In 97 aspen stands, the mean height of the five tallest trees increased from 60.6 inches to 100.7 inches during the same four years.

Ripple emphasized that he measured the tallest trees in these stands, not the entire population.

In 2001 and 2003, researchers could find no cottonwood trees that reached 2 inches in diameter at breast height. In 2010, researchers found 156 trees that had attained 2-inch diameters at breast height. Willow stems were as much as twice as thick after wolf reintroduction.

The research provides a “pretty convincing case that the introduction of wolves has changed the Yellowstone ecosystem,” said Aaron Wirsing, an assistant environmental and forestry professor at the University of Washington.

Wirsing cautioned, however, that ecosystems are very complex, “so it’s really hard to isolate the effect of any one change.”

Changing climate and wildfire management are just two of many factors that could influence willow, aspen and cottonwood growth.

“But it’s hard to ignore the evidence suggesting that wolves have played at least a strong role in driving changes,” he said.


>> http://www.jhnewsandguide.com/article.php?art_id=8091
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Re: Wolves Helping Aspens?

Post by Tita » Mon Jan 02, 2012 11:56 pm

The title confused me a bit at first. xD

Anyway, thanks for sharing that, Night. It was an interesting read.

Lol, 'bellybutton.' That confused me as well until I realized...
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Re: Wolves Helping Aspens?

Post by SolitaryHowl » Tue Jan 03, 2012 10:43 pm

Interesting read.
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Re: Wolves Helping Aspens?

Post by Alpha Female » Wed Jan 04, 2012 2:23 pm

SolitaryHowl wrote:Interesting read.
Please have at least three words in your posts SolitaryHowl, thanks! ^^
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Re: Wolves Helping Aspens?

Post by Tarbtano » Mon Jan 09, 2012 3:19 pm

I'm sorry to say this, but more recent research (the research for the article above originated mostly from the 80-late 90s, the one below is from the 2000s) indicates that the thesis that wolves foster plant growth due to the massive reduction of herbivores (Elk Herds in Yellowstone are down 80%); is simply not true

http://www.sciencedaily.com/releases/20 ... 111636.htm
"The results were surprising and have led us to refute several previous claims regarding interactions among wolves, elk and aspen in Yellowstone," Kauffman said.

The tree rings showed that the period when aspen failed to regenerate (1892 to 1956) lasted more than 60 years, spanning periods with and without wolves by several decades. "We concluded from this that the failure of aspen to regenerate was caused by an increase in the number of elk following the disappearance of wolves in the 1920s rather than by a rapid behavioral shift to more browsing on aspen once wolves were gone from the park," said Kauffman.

Surveys of current conditions indicated that aspen in study stands exposed to elk browsing were not growing to heights necessary to make them invulnerable to elk. The only places where suckers survived to reach a height sufficient to avoid browsing were in the fenced-in areas. In addition, aspen stands identified as risky from the predation risk map were browsed just as often as aspen growing in less risky areas.

"This work is consistent with much of what researchers have learned from studying wolves and elk in Yellowstone," Kauffman said. "Elk certainly respond behaviorally to the predation risk posed by wolves, but those small alterations to feeding and moving across the landscape don't seem to add up to long-term benefits for aspen growing in areas risky to elk."

The fall in the number of Aspen trees was not due to Elk overgrazing saplings, but the tree's own failure to fully germinate and grow due to weather and soil conditions. Elk grazed (note, grazed, not over-grazed) on trees at the same frequency no matter if wolves were present in the area or not. This shows wolves are not changing elk feeding habits significantly, nor are they protecting the trees. To say so is suggesting wolves are Keystone Species, in which is has been firmly established they are not, and therefore the ecosystem around them does not depend on Wolves for stability.
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Re: Wolves Helping Aspens?

Post by shadowwolf966 » Sun Jan 15, 2012 9:53 am

You know, I've actually heard of this before. Really I'm not that surprised; aspen trees and wolves are all part of the same ecosystem, and ecosystems tend to fail if one element is removed, in the case of the Yellowstone wolves. I'm glad though that this has been proven - it just shows how much we need wolves.
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Re: Wolves Helping Aspens?

Post by Tarbtano » Sun Jan 15, 2012 10:20 am

shadowwolf966 wrote:You know, I've actually heard of this before. Really I'm not that surprised; aspen trees and wolves are all part of the same ecosystem, and ecosystems tend to fail if one element is removed, in the case of the Yellowstone wolves. I'm glad though that this has been proven - it just shows how much we need wolves.
Read above please, wolves had nothing to do with the Aspen regrowth
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Re: Wolves Helping Aspens?

Post by BlackWarrior » Sun Jan 15, 2012 4:04 pm

Interesting share Tarbtano! Although if you think about it, many typed of animals can contribute to the healthy grow of wildlife. It is all part of a large ecosystem which relies on eachother. Perhaps wolves had nothing to do with their growth, although, they may have contributed to the same ecosystem.
Wolves kill elk, who usually eat saplings, and also the carcasses decompose which helps to fertilize the soil.
Your info does prove a valid point, but wolves may have had the smallest contribution to the growth of these trees.
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Re: Wolves Helping Aspens?

Post by Tarbtano » Sun Jan 15, 2012 5:42 pm

BlackWarrior wrote:Interesting share Tarbtano! Although if you think about it, many typed of animals can contribute to the healthy grow of wildlife. It is all part of a large ecosystem which relies on eachother. Perhaps wolves had nothing to do with their growth, although, they may have contributed to the same ecosystem.
Wolves kill elk, who usually eat saplings, and also the carcasses decompose which helps to fertilize the soil.
Your info does prove a valid point, but wolves may have had the smallest contribution to the growth of these trees.
plausible, but if anything; the biggest contribute to Aspen growth would be the species wolves have decimated the most in Yellowstone; the Coyote, since coyotes prey frequently on the small rodents that attack the Aspen's roots, saplings; and seeds (Elk only eat small portions of each tree). The amount of wolves moving out of Yellowstone and into Idaho seeking new territory and prey (Yellowstone elk herds down 80%) has allowed Coyotes to experience a slight rebound, allowing rodent numbers to fall a bit, contributing more to the Aspens then the wolves.

Its actually a frequent and annoying issue that any supposed good change in environments Wolves are present in, Pro-Wolf folk attribute it to the wolves, however true or untrue it might be. However when negative changes or events occur that are the fault of the wolves, Pro-Wolf folk look the other way and blame another party.
Prime example: Candice Berner case

Situation: Special-Ed teacher found mauled to death and partially eaten in Alaska, bite marks, tracks; and saliva all point to predatory wolf attack

Pro-Wolf audiences statements:
"Bears did it"
"Coyotes!"
"Someone's dog"
"Murder"
"A hunter using wolf parts to frame wolves to allow hunting!" (I WISH I was joking about this one)

When it was found wolves did indeed kill this woman (not before eating her alive), I saw these statements

"She was a hunter and the wolves knew!" (REALLY wish I was joking about this one)
"They were defending their pups!" (not right time of year, and wolves never kill in defensive situations)
"She attacked them!" (she was unarmed)
"Let me tell you this; Dinosaurs were in no way, shape; or form inferior to your wolves."
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