Driving down I-94 recently, I noticed a bright orange patch of butterfly milkweed, wild bergamot, and pale purple coneflower growing along the highway embankment. The plants were in bloom and stood out amongst the surrounding vegetation, even at 75 miles an hour. The plantings were so vibrant that we were inspired to exit, park, climb down the retaining wall, and take pictures. On the ground, we saw places where people had dug up plants for their gardens. This planting was the result of new methods for roadside vegetation planting, establishment, and maintenance specified in Native Seed Mix Design for Roadsides, a report prepared for MNDOT by Kestrel Design Group in 2010. The stated purpose of this manual is to create plantings that meet the following design criteria.
- maintain visibility and safety for roadside travelers
- withstand harsh conditions
- minimize maintenance costs
- minimize erosion
- improve water quality
- infiltrate stormwater runoff
- maintain good public relations
Furthermore, the manual identifies additional practical goals that really stand out for their down to earth sophistication. These include plantings that can be implemented and maintained by non-experts and allow for local sourcing of seeds based on availability. What impressed me about this set of design objectives is that they are responsive to site context, user capacity, as well as social and ecological goals. Beyond that, this guidance is applicable not just to roadsides, but to the landscapes of our cities in general. The last of the design criteria is perhaps the toughest one – “maintain good public relations.”
This manual reflects the rise of green infrastructure as an emergent paradigm for understanding urban ecology and landscape management. People’s perception of vegetation and ecology is shaped by narratives and preconceptions. Aside from a species’ appearance and ability to survive in a place, our notions about why it is there are based on a story. On one hand you have the status quo, lawns and landscaping. Native plant restoration is a newer concept, whose aim is to re-establish the wild vegetation that was present before the land was developed. Parallel to this is the idea of invasive species, typically exotic plants and wildlife that have naturalized and can outcompete the natives. Green infrastructure considers vegetation, soil, and water as essential living systems that provide ecosystem services such as aquifer recharge, urban heat island mitigation, carbon sequestration, etc. These narratives frame the ways we plan our interventions in the landscape, and allocate human and fiscal resources to accomplish goals. High maintenance landscapes and maintenance practices are becoming wasteful and expensive. Likewise, the effort associated with restoring native plant communities in disturbed locations can easily devolve into an endless struggle against the inevitable species that are most suited to dominate. In the coming decades we will need to make decisions about the extent to which we wish to garden our landscape versus finding better ways to let our landscape do some of the work for us.
In his book, Principles of Ecological Landscape Design, Travis Beck proposes a new style of planting design that is cognizant of how plant communities form, evolve, and grow particularly in the context of challenging human environments. At the core of Beck’s work is the notion that to be sustainable, the landscapes of the 21st century should provide environmental services beyond looking pretty while demanding fewer resources. His premise is that by harnessing ecological processes such as competition, disturbance, and succession, land managers can create lower input landscapes that can still have the aesthetic qualities that are expected by the public. In the work, Beck cites examples of how this approach is being implemented at the institutional, park, and corridor scale.
Storm King Art Center Grassland Plantings
In one example, the Storm King Art Center in Mountainville, New York has been converting its turfgrass areas into simplified native grass communities since 1997. Their land manager has been experimenting with different seed mixes that contain many of the same core species in each mix, but by editing the mix to account for variables such as soil moisture and desired height he has been able to create mixes that are low maintenance, effectively suppress weed competition, are drought tolerant, and provide a unified yet diverse backdrop for their sculpture park.
This approach tends to work most intuitively with larger sites like Storm King, but the techniques involved can work on a small residential lot. There is a shift in terminology from management to maintenance as we move to the smaller scale. This is the difference between maintaining a static landscape condition through regular human input versus allowing a landscape to evolve with targeted and minimal human interventions. High input landscapes will never disappear entirely, but we will see them shrink over time to the places where they are necessary. So, the question then becomes: How can we can we move to more of a management paradigm within the urban landscape and still keep things looking attractive?
The plantings on I-94 show that even though erosion control and stormwater management are priorities, so are flowers that inspire people to jump over a highway embankment and dig plants out of the ground. This is especially true in residential and commercial landscapes where the expectation is mown lawns and showy perennials. According to Beck, the sensible design approach is to keep it simple and proportional to the scale of the site. Picking a limited palette of the right species that can outcompete weeds and persist through stressful periods is one basic recipe for success. However, the ultimate goal is to develop a design approach that not only works, but is able to establish itself in the complex landscape of human perception. What I find appealing about the “green infrastructure” narrative is that it is about landscape performance and placemaking. This narrative appeals to planners and landscape architects, but it will be lost on the general public unless it is intuitively apparent and looks really great. For that to happen, the proof needs to jump out at you even when you are going 75 miles an hour.
Streets.mn is a non-profit and is volunteer run. We rely on your support to keep the servers running. If you value what you read, please consider becoming a member.