YELLOWSTONE NATIONAL PARK – During Glenn Plumb’s first summer here in 1999, he stopped at a small lake east of Mammoth Hot Springs and watched in wonder as a moose, standing in water up to its withers, munched on submerged plants.
“I was blown away,” said Plumb, a biologist who is now chief of Yellowstone’s natural resource branch.
The roadside lake has since dried up and disappeared along with the trumpeter swans and other animals that made the watering hole a regular stop.
No wonder it’s called Phantom Lake.
An eight-year drought has left scores of other ponds and wetlands dry and thirsty in Yellowstone. It also stands to force shifts in wildlife, the frequency of wildfires, the timing of mountain snowmelt and the growth of nutritious vegetation.
‘Accumulating signals’
“Drought inherently is not a bad thing,” Plumb said on a recent visit to the snow-covered lake bed. “But with long-term drought you start to see these accumulating signals.”
Casual visitors to the park may have picked up on some of them.
Parched streams and high temperatures last summer killed hundreds of fish and prompted park officials to temporarily close some waters to fishing.
Pothole wetlands in some areas have vanished, stealing prime habitat for the park’s struggling trumpeter swans.
Less vegetation
There’s less vegetation in the Gardiner basin for wildlife to munch on.
Drought-weakened conifers have fallen victim to increasing numbers of tree-killing bark beetles.
Drought also opens the door for non-native species to gain a foothold.
“Any time there’s a shift, there are winners and losers in every ecological community,” said Bob Garrott, a professor of ecology at Montana State University who has studied Yellowstone’s ungulates for about 20 years.
That’s not to say that anything is simple.
The effects of drought can be difficult for scientists to tease out and isolate in a place as complex as Yellowstone, where drought is nothing new.
The area’s history is rife with rapid swings between long stretches of wet and dry weather and a few years in between that make up average conditions, according to a study published last year.
Researchers in that study pieced together Yellowstone’s climate history over the last 800 or so years by examining rings from old trees in and around the park.
The work revealed regular wet and dry phases lasting 10 to 15 years.
Precipitation levels in the latest drought roughly match dry periods back to the year 1173, he said.
What’s different now, though, is that summertime temperatures are, on average, warmer and winters are milder, allowing snowpack to melt weeks earlier than normal, said Steve Gray, who worked on the study when he was a U.S. Geological Survey scientist before he was hired as Wyoming’s state climatologist.
“That can really stress these natural systems,” Gray said.
But those are some of the kinds of changes that can be expected if predictions for a warming global climate play out in the West, he said. Yellowstone will probably see more subtle signs of climate change than Glacier National Park with its shrinking glaciers.
“The consequences of long-term drought and long-term climate change will be in many cases slow-rolling events,” Gray said.
Full Story: http://www.billingsgazette.net/articles/2008/01/22/news
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