Tuesday, August 22, 2017

Roadside Revegetation with Native Plants: An Interview with Stefan Weber

Article by summer intern, Saige Patti.

Thousands of kilometers of highway in Ontario are lined with non-native legumes, which are ecologically useless for pollinators, and have shallow roots that aren’t as good at filtering water or preventing erosion as are native plants.
By Haljackey at English Wikipedia, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=31335717
Introduced plants like crown-vetch, black medic, white clover, and red clover have been popular choices for roadside plantings, which are aimed at preventing erosion of roadsides, but short roots and low salt tolerance make them less than ideal for roadside vegetation. A native tallgrass prairie community may be the best option for roadside plantings.

Roadside revegetation with native plants 

Roadside revegetation with native plants is being studied by Stefan Weber, a PhD student in the Biology department at McMaster University. In 2016 the Ontario Ministry of Transportation put out a request for proposals for their Highway Infrastructure Innovation Program Fund to study the best practices for establishing native roadside vegetation. Now, Weber’s project has two sites on highway number 3 outside of Tillsonburg and Norfolk county, and two sites in Saint Mary’s on highway 7.

Weber says the primary step to restoring habitat is preparing the site adequately. It can take two years to get rid of most of the invasive and noxious weeds, and even then the weeds and invasive species can persist. “I love the phrase ‘undressing a salad’,” he says, “It’s impossible to undress a salad. If you want to undo changes that have been made to the biotic community, it might not be possible; so many things have happened in terms of changes to soil structure and soil chemistry. It may not actually be possible to revert some roadsides back to the native landscape.”

blue vervain
It can be extremely difficult to remove non-native seeds from the soil seed bank, and multiple methods can be used. One method includes repeated herbicide spraying and tilling, but excavating can usually be more effective. Completely removing the first foot of soil down to the subsoil can remove the seed bank and nitrified soil. Native plants are tolerant of low-nutrient environments, so eliminating nitrogen from the soil will mainly affect non-native weeds. Prairie plants are adapted to colonize mineral soils; areas with sand, alvar, or exposed rock and gravel. This is because these prairies are early-successional communities – they are made of plants that are the first to appear when plants colonize an area. If the community was left undisturbed it would eventually be succeeded by ‘late successional’ communities like forests.

Weber says that we can keep our tallgrass prairies around by keeping these communities in an early state. This can be done by managing them with grazing or mowing. Historically, these prairies were maintained with fire by First Nations people. In a roadside setting, mowing is an essential activity for keeping prairie plants thriving. It helps eliminate competition from fast growing weeds which can shade these prairie species out.
“A successful project requires choosing species that are most appropriate for the physical characteristics of the restoration area,” says Weber. “The goal is to build what we want to see into the future, not recreate some historical scene that doesn’t exist anymore. We can’t travel back in time, so that’s not really the point.”

More Benefits
Photo Credit: Roadsides: A pollinator patch over a time
Benefits of roadside plantings include helping to control runoff, erosion, and drifting snow. Another benefit is that, “In the long term, arguably a native planting is more cost-effective than a non-native planting,” Weber says. He explains that native plants are more robust and tolerant of local climate conditions since they evolved here.
Often, plantings are done with two or three Eurasian legumes. The lack of biodiversity makes it easier for other weeds to move in, since there are niches which aren’t filled. Diverse perennial plantings that include groundcovers, taller perennials, and both early and late flowering perennials allow you to work with nature as opposed to against it. Additionally, non-native plants are not as efficient at the job they are meant for. “While [non-native legumes] do germinate right away and green up within a year, they don’t root very deeply, so they’re not really controlling a lot of erosion and runoff… the slope will continue to erode under the canopy of the plants to the point where you get channels punctuated by communities of legumes. After five or ten years you’ve got large-scale erosion undermining that original planting.” Weber explains.

brown eye Susan
Weber says that a better choice for restoration is to focus on really fast-growing species, like native wild ryes such as Canada wild rye, Virginia wild rye, and riverbank wild rye. These waist-high plants will germinate almost instantly and often flower and seed within the first year or two. They provide native cover and then allow slower-growing perennials like milkweed to grow. Other plants that are great to include in a restoration project are weedier natives like evening primrose, common natives like brown-eyed Susan, and legumes. “Most native legumes are not very common. Canada tick trefoil is probably the most common, and we use a lot of that.” Weber tells us. They are also trying to bring back the rare lupin plant, which only grows in sandy soil, but germinates quickly. It is ecologically useful because it provides early spring flowers, which is uncommon in native meadow communities.

While non-native buckthorn and dog strangling vine are recognized as weeds by many, Weber says that people forget that most of the roadside landscape is lined with introduced Eurasian pasture grasses. “To me, they’re almost more problematic than something like phragmites.” Weber says, adding that plants like “Smooth brome, Broamus enermis, perennial rye grass, creeping red fescue, tall fescue, barnyard grass, canary reed… They’re everywhere, they occupy more space and land than phragmites, for sure… People are just used to seeing them in the background – like the carpet and the drapes. We ignore how much land is occupied by these non-native pasture grasses and how hard it is to replace them.”

It may be possible to revegetate these areas with native plants, but MTO-owned roadsides that could be appropriate for this kind of project often have adjacent property owners who use the land to turn their tractor around, or even to farm. The MTO doesn’t generally intervene with these activities, but in the U.S. they have programs run by several agencies that encourage farmers not to farm past the edge of their property line, so that the land can be used for a buffer planting with native plants.

Weber is doing a review of the jurisdictions that have been engaged in different forms of roadside revegetation. “In the U.S. in 1975 the highway beautification act was passed, which means that 0.5%, of federal funding for roadside revegetation has to be spent on native plants,” Weber explains. That tiny little requirement has actually made a huge difference. Canada doesn’t have anything like that.”

Stefan Weber
The MTO doesn’t have any way to specifically fund these types of projects unless they’re required. Two major highways recently built in Ontario, the Windsor parkway and the 407 extension east, were both through ecologically significant habitat. Because of this, there were special requirements to include native plants in their roadside vegetation. Without requirements, it is likely that roadside vegetation will be planted with non-native plants.

Another good example of funding that Weber describes is in Iowa, where they have the Living Roadway Trust Fund. Money from toll roads and from other road taxes, certain natural resource department funds get allocated to the trust fund, and support roadside native planting. Canada doesn’t have the infrastructure or programs in place to support these kinds of projects, but Weber says “The Ministry of Transportation, the Ministry of Agriculture, Food, and Rural Affairs and the Ministry of Natural Resources have been having collaborative meetings, and I gave a presentation about a month ago to them about my research. They’re really trying to look for ways to move forward, but they’re also trying to move forward using what’s already in place in terms of funding.”
It’s a long road ahead, and Canada is just getting started, but with the right research and policy, we could soon see vital tallgrass prairie pollinator habitat along many of Ontario’s highways.