The beavers are gone from Greenough Park, but John Pierce is felling more trees there than the wood-munching rodents ever did.
Since 1995, when the park's advisory committee voted to restore Greenough's native habitat, Pierce has uprooted or cut down tens of thousands of Norway maples, an invasive species.
The botanist's efforts are changing the face of Missoula's favorite urban park, turning dense woods into a more open environment.
The Norway maples, which started taking over the park about 40 years ago, are disappearing in favor of cottonwoods, ponderosa pines, Rocky Mountain maples and other native trees, bushes and plants that thrive in the sunlight.
Those species were dominant in 1902 when the Greenough family set aside 40 acres along lower Rattlesnake Creek as a natural area for the public to enjoy.
Pierce, chairman of the advisory committee, has removed most of the young maples himself from more than half of the park.
"It's a lot of work, but it means a healthier ecosystem," he said.
Pierce spends several hours a week using a weed wrench to uproot them or a pruning saw to cut them down.
The city's urban forestry department takes down mature maples. They can reach 70 feet in height and create too much shade for native plants and the creatures that depend on them.
Most of the downed trees are left on the ground to decompose. The cleared areas naturally repopulate with native plants.
The downed trees create wildlife habitat, draw native birds and insects, stabilize the soil and prevent people from trampling the streambanks.
But they also create piles of ugly debris and a wildfire risk where once there was a picturesque canopy - bright yellow in the fall and cool green in the summer - that park-goers were accustomed to.
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"It's unsightly in the short term, but it gets things back to their natural state," Pierce said. "People have different reactions when they see me out here" clearing the maples. "Some understand. Some look like they want to strangle me."
Ann McDowell, who lives near the park and walks her dog there every day, lamented the loss of maples and the dense sanctuary they created.
"I think they're absolutely beautiful," she said. "I'm sad to see them cut down. I don't like how much more open it feels. We're losing all the color."
McDowell praised Pierce's dedication to the park, where he's a fixture - a bean-pole figure with long legs and calloused hands who works relentlessly on the vegetation, trails and stream flows in the city's most heavily used urban park.
"I suppose if getting rid of our beautiful maples is what needs to happen to make the park more native, then it has to happen," McDowell said. "But I'm still sad."
Ladd Knotek, a fish biologist with Montana Fish, Wildlife and Parks, said restoring the park's native trees is the right thing to do.
"It's like getting rid of knapweed in the grasslands," he said.
Knotek said removing so many trees could affect the trout creek's hydrology, temperature and habitat in the short term.
But the bigger problem, he said, is that five miles of the lower creek that once were braided have been channelized, diked and harmed over the years by landowners who remove vegetation from the banks and woody debris from the water, build rock dams and do other damage.
"The key thing is to get more native diversity, and that's what John (Pierce) is doing."
Reporter John Cramer can be reached at 523-5259 or at JohnCramer@missoulian.com.