Guest Post: Restoring Biodiversity in an Oregon Ravine

by Dr. Paul Otto

[Dr. Paul Otto is a professor of History at George Fox University in Newberg, OR. His full bio can be found at the end of his essay.]

Image courtesy of pxhere.com.

My partner, Lynn, recently published a wistful poem, “In this Green Green So Blue,” inspired by a camping experience in a pocket of Oregon old-growth forest with “vine maples and huckleberries,” “ferns and firs,” and “pale green streamers of moss” hanging from the trees. When we moved to Oregon from the Great Plains years ago, we soaked up this kind of natural environment whenever possible, having been starved of it while sojourning amid soy fields and corn rows.

Our new Oregon home struck a fine balance between the convenience of connection to town and engagement with the wild. The creek behind it emptied into the Willamette River, Douglas firs fringed the grounds, and big-leaf maples shaded the yard in summer. Best of all, our children could explore the broad ravine at the back of our lot. 

At first, it was enough that the trees were green and the landscape was wild. But in time I began to regret my ignorance of the native flora. I knew Douglas firs, of course, but I was more familiar with the invasive blackberries and English ivy than the maples, snowberry, and various ferns endemic to the area. I knew better than to think in terms of “natural” vs. “cultivated,” but a full appreciation of the native biodiversity escaped me.

After a bit of study, though, I began to understand what “belonged” and what didn’t. I learned about big leaf maples and vine maples; about red elderberry and oceanspray; about sword, lady, and bracken ferns—all of which grew in our ravine. And my learning made me appreciate them.

I gained insight, too, into native and invasive fauna—discovering, for example, that the squirrels I saw were eastern fox squirrels, one of two non-native tree squirrels introduced into Oregon’s urban areas in the early twentieth century. From there they expanded outward, especially into nut orchards and forests, driving out the native species. Among the native varieties are the Douglas squirrel and the northern flying squirrel, which glide on air better than they walk on the ground.

Eastern fox squirrel. Image courtesy of pxhere.

I’ve seen Douglas squirrels in other parts of the state, and Lynn saw a northern flying squirrel while growing up in Washington State, but my only sighting of a native squirrel on my own property—a western grey squirrel—in 20 years of living on the edge of a forested creek came 15 years ago. More competitive and faster to replicate, the fox squirrels drove the natives out long ago.

Hoping that challenging the fox squirrels’ dominance in one part of the forest might make room for the return of western grey squirrels or Douglas squirrels, I’ve tried various methods of rousting them from my yard, including shooting them with a pellet gun. Some members of my family protested, though, finding the killing of any animal inconsistent with a general embrace of nature and its ongoing gift of life.

I respect the position of those who hold that the killing of any animal is wrong, but in terms of restoring ecological balance, I’m not sure it’s viable. Even the Oregon Department of Fish and Wildlife is opposed to relocating or even rehabilitating non-native fauna, dictating that injured invasive animals must be euthanized rather than medically treated.

The strongest protest I heard questioned the whole idea of “invasive” species, comparing it to the denigration of immigrants to the United States. I understand the analogy—I myself am part of an “invasive species,” those who not only came from elsewhere but killed and displaced the Native population.

Of course, racial and ethnic differences aren’t the same as differences in species, but human beings as a species are invasive everywhere we go. Technological ability, complex social patterns, and advanced thought have empowered us to establish ourselves anywhere we want to. If there was ever a time a being resembling humans lived in equilibrium with other species, it was hundreds of thousands or even millions of years ago.

Yes, many Indigenous groups have lived in greater ecological harmony with their surroundings than colonizing groups, but human beings have always changed the land to one degree or another. As I’ve become better acquainted with Oregon over the past two decades, I’ve come to understand the difference between a natural order that develops slowly without the invasive hand of humans and one that is little more than not having a lot of people around. That old-growth campground that inspired Lynn’s poem helped me see this.

On the surface, what old-growth forests offer are big trees to gush about. But if you compare them with re-established forests, you’ll soon note a great diversity of flora (and fauna). Along the western flanks of Oregon’s Cascades, the oldest forests contain a mix of conifers and deciduous trees, with Douglas firs, cedars, and hemlocks cohabitating with big leaf maples, Oregon ash, and alders. The understory reflects this diversity, with red huckleberries, thimbleberries, blue and red elderberries, and Oregon grape. Closer to the ground you’ll find even more variety: trillium, wood sorrel, false Solomon’s seal, and a whole host of wildflowers I haven’t begun to learn the names of. Added to this botanical display are a wide array of animals.

What’s missing from this picture? Himalayan blackberries, English ivy, and other invasive species, which once made up most of the greenery in that ravine behind my house. Poking out of the mass were a few ferns, firs, and big leaf maple, but generally it was a tangled mess of bramble and vines.

Early in the process, a friend helps Paul build steps near newly transplanted Douglas fir and sword ferns; the upper bank still covered in English ivy. Photo by Paul Otto.

About 10 years ago, however, I began to restore the uncultivated parts of my property to something closer to its original botanical diversity. My community’s “trees for streams” program helped me in this project by providing free native grasses, shrubs, and trees. In those ten years, I’ve seen a huge transformation that has made this part of my lot far more appealing.

Why, you might ask, should I favor native plants over non-natives? Am I just being a purist? I don’t think so. Native plants not only increase biodiversity but also foster a healthier landscape. On my lot, for example, insufficient shade allowed blackberries to thrive. Along with the English ivy, the blackberries prevented other trees and shrubs from growing and providing cover. Exposed to the sun, the creek warmed. Without my restoration efforts, the ravine would have fewer trees, less wildlife, and a warmer, dwindling stream.

The upper bank is now dominated by sword ferns; great horn owls nest in the firs above. Photo by Paul Otto

Now, however, the creek is increasingly shaded by Oregon ash, rose spirea, and an impressively fast-growing cottonwood. Two western red cedars and a growing understory of ninebark, flowering red currant, thimbleberries, and vine maples cover the hillsides. The variety of ferns has expanded to include deer and maidenhair ferns.

We’ve seen an expansion of wildlife, too. Great horned owls have taken up residence—evidence of a growing rodent population. Because the stream runs deeper and cooler, great blue herons are feeding there. And my wildlife camera has captured video of the illusive grey fox.

Employment and other considerations limit my choices about where to live, but I can choose how I live in the space where I reside. My choice is to work with the ecosystem and not against it. I’m not trying to recreate a pristine wilderness, only reverse (or at least slow down) the impact of others’ choices.

Perhaps my efforts at controlling the eastern fox squirrel population have been misguided or ineffectual, but I know that cultivating a natural space by removing invasive plants and replacing them with natives has helped rebuild a longstanding but sensitive ecosystem. And in restoring this natural order, I find that I’ve been restoring myself.

A great blue heron visits the restored ravine; downstream, unrestored stream bank on neighboring properties. Video by Paul Otto

A couple of links:

Native vs. invasive plant species in OR

Native vs. invasive animals in OR

Dr. Paul Otto is a professor of History at George Fox University in Newberg, OR. An expert in the history of early America and Native Americans, he has authored The Dutch-Munsee Encounter in America: The Struggle for Sovereignty in the Hudson Valley and is currently writing a history of the use and development of wampum in the colonial northeast in the 17th & 18th centuries. An avid user of role-immersion pedagogy known as Reacting to the Past, he is also at work on several of his own scenarios.