EUGENE, Ore. (AP) -- The hike to the top of Mount Pisgah will be a little less shady from now on.

Douglas fir trees that overshadow the white oaks along the trail are being removed to help restore a bit of the savanna that once marked the Willamette Valley.

The fast-growing Douglas firs are 30 to 40 years old and have been encroaching on the older oaks, whose bowl-shaped canopies suddenly emerge like fans against the sky once their competitors are gone.

"It's almost like an archaeological excavation, unearthing these trees after so many years of fire suppression," said Darin Stringer of Integrated Resource Management, part of the team working on the 60-acre demonstration project in the Lane County park south of Eugene.

Prairie and oak savanna once covered about 1.3 million acres in the Willamette Valley, said Jason Blazar, stewardship coordinator for the Friends of Buford Park & Mount Pisgah.

The nonprofit group organized the effort. The state Department of Fish and Wildlife, the Bonneville Power Administration and the Forest Restoration Partnership helped pay for it.

Prairie and oak savanna are home to a wide range of species, some rare enough to be under consideration for federal listing as threatened or endangered, such as the Western gray squirrel, the Western bluebird, the wayside aster, a bat called the long-eared myotis, the Taylor's checkerspot butterfly and Oregon's state bird, the Western meadowlark.

The grasses and wildflowers once common across the prairie and savanna have succumbed to invasive species such as blackberries and Scotch broom, Blazar said.

For generations, American Indians managed the landscape, keeping fir trees at bay by regularly burning the prairie, which renewed the grasses and wildflowers and burned out unwanted tree seedlings, yet rarely climbed into the crowns of oak.

Restoration efforts have been occurring across the Pacific Northwest, Stringer said, such as on cliffs overlooking the Columbia River in Washington state, on 1,244 acres of private lands in the Coburg Hills and at a 455-acre project in the Middle Fork District of the Willamette National Forest.

The Confederated Tribes of Grand Ronde are considering a 1,900-acre project along the Santiam River.

At the Mount Pisgah project, Friends of Buford Park & Mount Pisgah placed signs along the trail and conducted tours during the summer to prepare park visitors for the changes.

While the group has heard plenty of positive comments from hikers, there have been enough concerns about shade to prompt them to leave some trees they had planned to remove, said Chris Orsinger, the group's executive director.

Eugene resident Wendy Harris said that while she had seen the signs this summer, it was still a shock to watch trees coming down. She said she supports the idea of savanna restoration but wishes it had been done at some less-popular location.

"I appreciate the job they're trying to do, but it will completely change the effect. I will no longer be able to enjoy the walk," she said.