Jan 4, 2018

Saving Oregon's savanna

The patch of oak savanna at Mt. Pisgah is one of the largest remaining in Oregon. Photo: Erin Ross / Axios

Across the United States, bits and pieces of an ancient — but man-made — ecosystem are being restored, sometimes at the expense of more common natural landscapes. For thousands of years, fires lit by indigenous peoples maintained oak savannas. Such forested grasslands were once abundant across the western US, but agriculture, lumber industry, and fire suppression have combined to bring them close to extinction. In Oregon's Willamette Valley, bringing them back is laborious work that sometimes involves sacrificing stands of other native trees.

Why it matters: Oak savanna are among the most diverse ecosystems in the U.S. and support species that aren't seen anywhere else. In the 1800s, 1.5 million acres of the Willamette Valley were oak savanna. Today, just 1-2% of that remains, echoing a decline in oak grasslands across the country.

What it is: A diverse prairie, dotted with oak trees. Buford Park at Mt. Pisgah, near Springfield, Oregon, has one of the largest remaining parcels of oak savanna in the state: a broad, sunny hillside that is open between the trees and full of wildflowers. It abuts oak forests, dry prairies and marsh-like wet prairies, and supports coyotes, bears and the occasional mountain lion.

Why it's there: In Oregon and much of America, indigenous peoples' burned dense forests to create open meadows and prairies. These grassy spaces supported a number of edible plants and provided a habitat for deer, elk and other food species.

It might seem strange to focus on restoring what was essentially a man-made ecosystem. But humans have been conducting regular burns since at least the last major climactic shift 5000 years ago. Almost as long as this ecosystem has existed, it has been stewarded by humans. The savannas and forests that once checkered the hills surrounding the Willamette Valley came from "defy the worldview of nature and culture being separate things." explains Ed Alverson, the natural areas coordinator of Lane County Parks, which has worked to restore areas of oak savanna.

How we know about it: In addition to records from the earliest settlers to the Willamette Valley, who came specifically for the vast savannas and now-gone prairies, scientists have also begun to map the habitat's extent by looking for microscopic, fossilized remnants of plants called phytoliths.

How they fix it: Because each mountain or valley is different, each restoration project is different. In some areas, native plants are added and invasive species are removed. What species go where depends on the specific soil chemistry of the environment, which can vary from hillside to hillside. They start controlled fires to mimic the ecology of the past.

In many areas, it would be too labor intensive to restore oak savanna. If a pine forest is dense and established, the plants, fungi and bacteria that oak savanna thrives with will be gone. Instead, Alverson focuses on easier restorations, and managing the ecosystem that remains.

Where we are now: Many of the projects along the west coast are in their infancy, but the impacts of the rare habitat are visible. The Klamath Bird Observatory says they've seen a noticeable shift in the types of birds passing through.

There's more: This ecosystem isn't unique to the Willamette Valley or the Northwest. Similar restoration efforts are underway in California and the Midwest. Many projects to restore oak savanna are modeled after a highly successful effort in Illinois in the 70s and 80s.

Yes, but not everyone loves the restoration efforts, at least not initially. At Mt. Pisgah, some objected to clearing trees to restore savanna, especially along popular trails. Others disliked the use of herbicides to remove invasive species. But Jason Blazar, the stewardship director at Friends of Buford Park & Mt. Pisgah, says that once they explained the long-term goals and the rarity of the ecosystem, people come around.

"When they walk through the landscape the spring following an ecological burn, and hear the meadowlark sing perched upon a small snag in a sea of tall camas," says Blazar, "they get it."

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