Tag: oak savanna

When Euro-American settlers arrived in the Willamette Valley of Oregon in the mid-nineteenth century, they encountered a landscape far different from what you see there today.  Historical accounts describe open fields of tall grasses and wildflowers with a few oak trees interspersed.  A biodiverse paradise for songbirds, butterflies, and other species that rely on an open system. Maintained by the indigenous people, the Kalapuya, for centuries—the expansive landscape must have been appealing to many early settlers as well.

Flash forward to modern times—and the Willamette Valley is now a complex of agricultural fields and urban and suburban environs. Most of Oregon’s major population centers, like Portland and Eugene, as well as the state capital, Salem, are in the Willamette Valley. Currently, more Oregonians live and work in the Willamette Valley than in any other part of the state and over 170 crops are grown there. Development has completely altered the landscape. Only about 1% of the Oak Savanna habitat that was once prominent in the area remains. Wetlands, riparian areas, and oak woodlands have all suffered major losses in the Willamette Valley.  

A Few Hold Outs

However, there are still a few holdouts and a lot of effort to maintain and restore what remains of these important habitats. One of the holdouts is Finley National Wildlife Refuge, just a few miles south of Corvallis, OR. And one of the people putting forth the effort to maintain and restore is Nate Richardson, a wildlife biologist for the U.S. Fish and Wildlife Service (USFWS). 

I met up with Nate at Finely to hike the Mill Hill Loop and chat about Willamette Valley habitats and the challenges of maintaining and restoring them. 

Into the Woods

Nate and I started out on the trail hiking through oak woodlands. Nate pointed out the structure of the forest. There were a lot of smaller, younger oak trees with a few larger oaks and an understory of shrubs—typical of this habitat type. Oak woodland is a priority habitat in Oregon and provides for many species of concern in Oregon, such as the acorn woodpecker and white-breasted nuthatch. Though we didn’t see any during our hike, the Mill Hill Loop is an excellent spot to look for woodpeckers, said Nate. 

A Tale of Two Trees

However, despite the many functioning aspects of the oak woodland we were hiking through, it didn’t take long before we spotted one of its biggest threats—conifers.  Nate explained how Douglas-fir trees grow much quicker than Oregon’s oak species, like the Oregon white oak. Because of this difference, when Douglas-fir inundate an oak woodland, they tend to outcompete the oak by shading them out.

As we continued down the trail, we could see several examples of Douglas-fir trees in direct competition with the oak.  We even saw a few dead oaks as a result. 

Managing with Fire

In the past, conifer and shrub species were kept in check by the indigenous people of the Willamette Valley—the Kalapuya. For hundreds of years, the Kalapuya used fire to maintain the open habitats of the Willamette Valley for forage and hunting. Without fire, woody species have encroached further and further into the foothills of the Willamette Valley, such that much of the oak habitats, especially upland prairie, has been all but eliminated. 

Mixed Up

As we hiked, further along, the suite of species gradually changed from oak to a mixed forest, to one dominated by conifers. With a much denser overstory of Douglas-fir, our path became almost completely shaded, and oak became non-existent. Instead, big leaf maple made up the deciduous canopy with many shade-loving (or at least shade-tolerant) plants in the understory. Sword fern and snowberry were two species I spotted. 

In general, conifer forests like the one we were hiking through are very common in Oregon and becoming more common in the Willamette Valley.  But that doesn’t mean they don’t have value. Mixed/conifer forests provide habitat for many species, such as black-tailed deer and Swainson’s thrush. Nate told me that even Grey Jay (a species I usually associate with higher-elevation conifer forests) will occupy the site in the winter.  

Everyone Likes Ducks

At one point, the dense trees opened up and a brightly lit clearing of grasses and willows came into view through the thicket. A wetland! Wetlands are areas that tend to retain moisture for a large part of the year.  These soggy bottomlands also provide critical habitat for many species, like wood ducks and beavers that frequent the area. Wetlands are also a target habitat for restoration and protection, as many have been drained for other uses. 

Though Nate works for USFWS, he spends most of his time working on restoration projects that are on private lands; many of which are wetland projects. “People like ducks,” said Nate, so they tend to be the focus of these projects. In fact, Finley was originally established to provide nesting habitat for waterfowl. In this case, the Dusky Canada Goose lost a great deal of habitat from land subsidence following an earthquake. Of course, now the refuge takes a multi-species approach to management, focusing on restoring habitat for many species. Coincidentally, even if a wetland is established in the name of duck, many more species will benefit, including humans. Wetlands provide tons of ecosystem services! Wetlands are amazing water regulators and filters, for example. 

Pure Gold

Then, at long last, we arrived! An upland prairie! One of Nate’s favorite habitats in the refuge. According to Nate, upland prairie habitat is really important to many species of concern in Oregon, like the Oregon Vesper Sparrow and the Streaked Horned Lark.  Plant species like Kincaid’s Lupine, Nelson’s Checkermallow, Bradshaw’s Lomatium, and Willamette Daisy, are also rare but can be seen here. Plus oak savanna habitat is typically the only place in Oregon’s Willamette Valley you are likely to find the state bird—the Western Meadowlark.  

Dominated by grasses, like Roemer’s Fescue, and herbaceous wildflowers, like Oregon sunshine, oak savanna is a colorful Smörgåsbord in early spring. The diversity of grasses and forbs in oak savanna habitat also attracts a diversity of insects, which in turn attracts a lot of birds. Essentially, the entire system is driven by the right mix of native prairie vegetation. 

Time and Money

However, when it comes to restoration, getting that right mix can be a huge undertaking. Nate explained that the open prairie we were looking at used to be a lot of douglas-fir trees and hardly any grasses.  It took a lot of work, time, and expense to bring it back to a near-native state. Cutting down trees, mowing, and burning, as well as replanting native species, are all part of the restoration process.  A process that doesn’t really have an end, as continued mowing, burning and plantings are often needed to maintain the habitat. For example, golden paintbrush, a plant that was once extirpated from the state, needs regular burning to be maintained. Also, as a hemiparasitic species, golden paintbrush benefits from associations with other native species, like Oregon sunshine. 

Is it enough?

As you can see, restoration work can get pretty complicated. Research into understanding what species do best, and in what conditions, is another important component of restoration work. However, there is also the question of just how much to restore. Do you want an oak savanna that is 90% native, or will 60% do? Nate talked about the challenges around this sort of decision-making. If you can get an ecosystem 60% restored for a lot less cost and effort, maybe that is enough to restore the ecological function of the prairie. And if that is the case, shouldn’t we stop there? He didn’t have an answer. Nor do I. But these are important considerations for any restoration and/or management plant. When do we let nature do its thing? 

Connect the Dots

Another perhaps even bigger challenge when you are trying to restore an ecosystem that is about 99% lost is connectivity.  Nate explained—Many species need large tracts of land and the ability to migrate between and through the landscape in order to obtain desirable population densities.  Population density is simply the number of individuals in a population that live in a given area. “Song birds really need it,” said Nate, “small places are great, but song birds need more.”  When there is a large enough tract of land that is not segmented, the densities of birds, like the Western Meadowlark, are substantially increased. 

The question is how do we create connectivity? We don’t want the “traditional corridor of trees,” said. Though there is no simple answer, Nate does hope to improve conditions where he can. As mentioned earlier, a lot of the restoration work Nate does is off the refuge property, often in locations adjacent to a refuge. Helping landowners establish habitat on their property can expand the land area that supports species. Then, as Nate described, others see what is happening and want to get involved “and things spiderweb out.” 

A Rare Sight

One of the rarest habitats on the refuge (and in Oregon) is the wet prairie. Due to their location, Occurring in lowlands, especially floodplains, many wet prairies have been converted to agricultural land. Wet prairies are also different from upland prairies as they retain water for a portion of the year making them ideal for plants that like to occasionally get their feet wet. Water-tolerant grasses, like tufted hair grass, sedges, and wildflowers dominate wet prairies.  Unfortunately, the wet prairie is also rare on the Mill Hill Loop—we didn’t see any. 

According to Nate, you have to go to the Prairie Overlook to see wet prairie habitat. Besides being wet prairie, the land adjacent to the overlook is designated a Research Natural Area, set aside for education and research. It is also really special because it is one of the few places in the Willamette Valley that was never tilled. 

Important Matters

As we finished the loop and made our way back to park headquarters, I asked Nate why people should care about protecting and restoring wildlife habitat. For Nate, it is all about awe—only in these places can you see a rare blue butterfly or hear a woodpecker cackle, or watch ten thousand geese take flight off the marsh. Experiences like these can inspire people to care about and appreciate the ecosystems around them.

Awe and Inspiration

We were nearing the golden hour as Nate and I parted ways both to our respective homes. But before I left, I pulled over at the Prairie Overlook to take a peek at the wet prairie Nate had mentioned earlier. With my mood light and the sun setting low in the sky over an expansive golden landscape, I really did feel a sense of awe and appreciation. It is amazing what a little bit of nature (and science) can do for the human spirit.

Nate Richardson has worked as a wildlife biologist for the USFWS for 12 years restoring native habitat for the Partners for fish and wildlife program. He got his BS in wildlife science at Oregon State in  2004 focusing on avian conservation and management. In his free time, he enjoys hiking, climbing, fishing, and spending time with his 9-year-old son.