Michal Wert: Roadside vegetation critical for native species

Submitted photo##Michal Wert (standing) and associate Rob Tracey (kneeling) of the Native Plant Society of Oregon assist with a native plant landscaping project commissioned by the county in conjunction with its 2014 reconfiguration of the intersection of  Abbey, Kuehne and Hendricks roads, north of Lafayette.
Submitted photo##Michal Wert (standing) and associate Rob Tracey (kneeling) of the Native Plant Society of Oregon assist with a native plant landscaping project commissioned by the county in conjunction with its 2014 reconfiguration of the intersection of Abbey, Kuehne and Hendricks roads, north of Lafayette.

The landscape explorers encountered in the Willamette Valley in the early 19th century bears little resemblance to the landscape today. A last refuge of a once-extensive prairie landscape remains along our public roadsides, however.

In 1841, George Emmons, a surveyor with the U.S. Exploring Expedition, wrote this description of his view of the Willamette Valley from adjacent foothills: “From the top of these [hills] at an altitude of about 1,000 feet ... prairie to the south as far as the view extends ... streams being easily traced by a border of trees that grew up on either bank ... white oak scattered about in all directions.”

Early surveys by the General Land Office around 1850 indicate the Valley hosted a mosaic of vegetation types.

The relatively flat Valley floor was covered by savanna dominated by Oregon white oak, interspersed with wet and dry prairie and wide strips of riparian forest marking meandering riverbanks. The journals of pioneers of the Willamette Valley in the mid-19th century also described broad prairies bordered by thick wooded bands along the rivers.

The Cascade and Coast Range foothills framing the Valley were timbered. Stands ranged from open oak woodland to closed, conifer-dominated arrays of Douglas fir, western hemlock, western red cedar and Sitka spruce.

However, trappers and settlers did not arrive to a pristine wilderness. Native Americans had long been using fire to create and maintain the Valley landscape.
Pioneer journals described extensive fires filling the Valley with clouds of smoke in late summer.

Guest Writer

Michal Wert, who lives north of Newberg on Chehalem Mountain, serves on Yamhill County’s Road Improvement Advisory Committee and chairs its Roadside Vegetation Management Technical Advisory Committee. An active member of the local Cheahmill Chapter of the Native Plant Society of Oregon, Wert was among native plant advocates helping plant Roemer’s Fescue grass plugs in the triangular island created at the county’s Abbey-Kuehne-Hendricks intersection.

The Kalapuyan tribes, which had occupied the Valley for thousands of years, set the fires to control the growth of underbrush and trees. This made it easier to hunt and improved growing conditions for major food sources, such as camas.

Oak savanna groves were favorite homesites for Euro-American settlers. They continued altering the vegetation by cutting trees to provide wood for homes and businesses and clearing space to grow their own food crops.

They halted the annual burning in the 1850s. That allowed forest lands to encroach onto former prairies and savannas.

Today, much of the former prairie has undergone yet another transformation. It has been planted in grain or grass seed.

In addition, through much of the 20th century, the damming and channelization of streams and rivers, and the installation of drain tiles and digging of ditches on wet prairie land, reduced or eliminated natural winter meandering, ponding and flooding of water.

As a result of this human intervention, very little original vegetation remains today.

Most emergent wetlands, once key contributors to the native biodiversity of the Willamette Valley, have been drained and placed under cultivation. Most riparian timber stands have undergone logging and degradation by non-native species, including reed canarygrass and Himalayan blackberry.

As a result, our public roadsides have come to harbor the most important remnants of our biological heritage. They provide valuable habitat because they stretch across the landscape, connecting remnant habitat patches to create a linear refuge for wildlife.

This is especially true in agricultural regions and other highly modified landscapes, where roadsides may be the only semi-natural habitat remaining.

Unfortunately, roadside vegetation management sometimes features a single-minded approach — get it out of the roadway, cut it to maintain visibility, and spray it with herbicides so it doesn’t return. Native plants and the wildlife depending on them have often become casualties in the process.

Yamhill County, which manages 716 linear miles of roadway, encompassing 1,432 lane miles, has come to recognize that environmentally sustainable management demands more complex methodology.

In 2014, the county commissioners appointed a diverse group of experts to help its Public Works Department develop an integrated approach to roadside vegetation management. Organized as the Roadside Vegetation Management Technical Advisory Committee, it proceeded to developed a plan combining motorist safety, noxious weed control and soil stabilization with protection of the natural environment. 

A major effort in support of these goals involves enhancement and expansion of existing populations of native plant populations along roadsides and introduction of new native plant communities in areas of new construction. That offers several advantages.

Native plants provide a practical solution to weed management, requiring less herbicide spraying and expensive hand labor. They provide increased shelter for wildlife, greater biodiversity, better water quality and enhanced protection for endangered species.

Because they grow deep, sturdy roots, they improve erosion control without requiring irrigation. And once they become successfully established, they require very little maintenance, reducing the need for mowing and weed control measures.

When the Abbey-Kuehne-Hendricks intersection north of Lafayette was reconfigured in 2014 to improve traffic flow and automotive safety, the county’s Public Works Department asked the local chapter of the Native Plant Society of Oregon to team up with the Yamhill Soil & Water Conservation District on a landscape plan capable of serving as a demonstration project for practical roadside vegetation management.

The goal was to use native plants to eliminate invasive and noxious weeds and create an attractive but low-maintenance landscape on a triangular island bounded by three roads. In the process, the department aimed to establish a model it could apply countywide.

Public Works graded and prepared the triangle and both the inner and outer roadsides of the three-way intersection for planting.

The Native Plant Society developed a planting plan and marshaled volunteers to handle the planting of an appropriate native prairie seed mix. Soil and Water provided staff assistance and plants grown at its native plant nursery at Miller Woods.

The triangle was planted in 2016 with a seed mix featuring 20 wildflowers and one grass. The mix was especially created for roadsides and further tailored for this particular site.

The adjacent roadsides were planted the following year with native plants provided by Solid and Water. And some of the plants have already produced their first blooms.

The Public Works domain includes more than a dozen sites providing habitat for the endangered Fender’s blue butterfly and its host plant, the threatened Kincaid’s lupine.

Although this effort was initiated to avoid a lawsuit for non-compliance with the Endangered Species Act, the department has proactively worked to enhance special maintenance zones intended to protect the species. The Greater Yamhill Watershed Council has agreed to help manage these sites, creating yet another partnership benefiting both parties.

Finally, Public Works is in the process of conducting an inventory of county roadsides to document areas marked by severe erosion, infestation with invasive or noxious weeds and remnant survival of healthy native plant communities. It is being assisted in that effort by university interns and Native Plant and Soil and Water personnel.

Roadside surveys represent yet another tool in an arsenal designed to foster responsible management of Yamhill County roadsides.

This summer, Public Works and Soil and Water intend to begin working with willing landowners to address roadside erosion along their borders. The inventory will help identify sites to target.

Roadsides, by definition, don’t qualify for wilderness or wildlife refuge status. But in many parts of our county, they represent the only remaining safe harbor for native plants, key plant pollinators and songbird populations. So it makes no sense to unwittingly destroy this habitat.

Good roadside management is capable of saving taxpayer money while also minimizing negative impacts to water quality and the environment. It is capable of benefiting adjacent landowners while also promoting safer and more attractive roadsides for the traveling public.


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