MPR’s Mary Losure reports that after massive storm in BWCA, which many considered a catastrophe, is providing a rare opportunity for scientists to study how a wilderness recovers from a massive natural disturbance. Losure interviews Alan Heine, forestry Professr at University of Wisconsin; and Lee Frelich forest ecologist at University of Minnesota.
In July 1999, a windstorm swept through the Boundary Waters Canoe Area Wilderness with hurricane force. Straight line winds toppled tree trunks like dominoes, flattening more than a third of the million-acre wilderness.
Transcripts
text | pdf |
MARY LOSURE: Alan Haney knows the Boundary Waters Canoe Area Wilderness well. For 25 years, the forestry professor at the University of Wisconsin at Stevens Point has studied the effects of disturbance, such as fire and logging, on the forest. He has 100 study plots, each 20 acres, scattered across the Boundary Waters Wilderness and surrounding forests. So when the storm cut a swath through his study area, he was perfectly positioned for a before and after study.
ALAN HANEY: Overall, the system seems to be adjusting remarkably quickly, more so than we would have anticipated given the severity of the storm.
MARY LOSURE: Among the tangle of downed trunks, small trees and shrubs are flourishing. Woodpecker populations are thriving. Some species of songbirds, including magnolia warblers, mourning warblers, winter wrens, and white-throated sparrows, are increasing. Haney has also found evidence that new bird species are moving into the blowdown area.
ALAN HANEY: One of the biggest surprises that we found was the yellow-bellied flycatcher, a relatively lesser known species, which is certainly in the area and is well known from the area. But we had not previously recorded the yellow-bellied flycatcher on any of the plots prior to the storm. But that species was well represented on every plot that was impacted by the storm.
MARY LOSURE: Now when the crews survey the downed forest plots, the flycatchers come in close to watch. Like all the species native to the boundary waters, they've lived for millions of years in a Northwoods ecosystem that evolved with massive disturbance. The area was frequently swept by wildfire until the fire suppression policies of the past century. Windstorms, although much smaller than the July '91 storm, are also fairly common.
So Haney and other scientists expected the forest to be resilient, but he's still been surprised by the details. Crews crawling through the fallen tree trunks have noticed lady slippers and other kinds of orchids blooming undisturbed on the forest floor.
ALAN HANEY: And then perhaps the most pleasant surprise of all in that regard was that on one of the sites where 15 years ago, we had recorded the very beautiful calypso orchid in bloom. We found that in bloom again this year under the debris, and we hadn't seen it on that site in 15 years.
MARY LOSURE: Inside the wilderness boundaries, the forest has been left to recover on its own. But outside the wilderness, some storm damaged plots have been logged to salvage the downed timber and reduce the danger of fire. Haney's surveys have found bird numbers and diversity on these logged plots are much less than on unsalvaged plots. He's found six to 10 nesting birds per logged plot, compared to as many as 60 on the unlogged sites.
University of Minnesota forest ecologist Lee Frelich has also been studying the effects of the storm. He's been surprised to find that two species of trees, paper birch and white cedar, withstood the winds much better than other species. He's found clumps of ancient cedars 500 to 1,000 years old that the wind didn't harm at all. In part, that's because the slow-growing trees are so short, some only 4 to 5 feet tall.
LEE FRELICH: Well, they look kind of large bonsai. They have very thick trunks for their size. They have a lot of dead branches. They have a few little tufts of live foliage here and there. Some of them kind look like the bristlecone pines out in California. They just have one strip of live bark and maybe one live branch on the tree. So there wasn't much for the wind to push on.
MARY LOSURE: One question scientists had hoped to study was how well large animals such as moose and wolves can navigate the blowdown areas. But so far, there's been no funding for such a study, so scientists can only guess. Frelich says he's noticed that moose seem able to make their way through, and he suspects the horizontal logs act as a highway for smaller mammals. He and his students were standing in the forest last summer when they noticed a fissure, a dark-furred member of the weasel family, regarding them from a log. The animal turned and quickly disappeared, making its way effortlessly through the tangle. I'm Mary Losure, Minnesota Public Radio.