GOOD-NEWS STORY: SCIENTISTS DISCOVER ROAMING BUFFALO MASSIVELY SHIFTED PRAIRIE ECOLOGY & CREATED BENEFICIAL "ENDLESS SPRING." One of the last herds of free-range Buffalo – 4500 head inside huge Yellowstone National Park – were studied by researchers who have established that Bison grazing patterns significantly improved the prairie land of the Great Plains.
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"Herds of bison milling through Yellowstone National Park may seem aimless to the average visitor, but a new study reveals the animals are hard at work engineering their ecosystem. By rigorously mowing and fertilizing their own patches of grassland, the big herbivores essentially delay spring until late summer…
"For the new study on bison in the journal PNAS, researchers wanted to follow bison as they 'surfed' the green wave in Yellowstone National Park. Scientists began tracking the herd’s movements using GPS collars in the mid-2000s. But researchers noticed something odd about the 4,500 bison in Yellowstone: tracking data showed that while other ungulates moved with the wave to higher elevations, the bison lingered behind, reports Tom Bauer at the Missoulian.
“'They surf the green wave early in the spring,' co-author Jerod Merkle, a migration ecologist at the University of Wyoming says, 'but at some point, they stopped. [M]any bison did not reach their highest summer ranges until well after the green wave had passed.'
Even more surprising, when researchers analyzed the bison dung, they found that the animals experienced no nutritional deficits when letting the green wave wash by them. 'It threw us for a complete loop,' study co-author Chris Geremia, a National Park Service scientist, tells Ed Yong at The Atlantic. 'How can they fall behind but still have an incredibly high-quality diet?'…
“'We knew that bison migrated, we figured they followed the green wave, but we didn't know that their influence on the landscape could affect the entire way that spring moves through the mountains and valleys of Yellowstone,' Merkle says in a press release. 'They are not just moving to find the best food; they are creating the best food. This happens because bison are aggregate grazers that graze in groups of hundreds, or more than a thousand animals.'
"Yong reports that this has long-term impacts; when the green wave returns the following year, the heavily grazed areas have a more intense spring that lasts longer than in other areas. According to the press release, the effect is so pronounced that researchers can see the difference between heavily grazed and lightly grazed grasslands on satellite maps…
"'Today there is growing effort to restore bison to habitats they once roamed,' Geremia tells Osborne. 'As we seek to reestablish bison, this study shows us what large bison herds are capable of when they are allowed to seek out the best forage and move freely across large landscapes.'"
Yellowstone Bison Engineer an Endless Spring to Suit Their Grazing Needs
The cycle of grazing and fertilizing prolongs spring-like vegetation in grasslands and makes green-up more intense in following years