#What'sTheReference — Botanically Speaking

I attended a symposium at Ryerson University. It was hosted by Jonas Spring, Toronto chapter president at Landscape Ontario alongside Sam Benvie, Intructor and Academic Coordinator in the Landscape Design program at Ryerson. They invited a bunch of ecologists (and one landscape architect) to speak about a topic that was probably at least a little bit strange to an audience of mostly landscape designers/horticulturists. The topic was stated in the form of a question: “What’s the reference?”

Alvars are ecosystems dominated by huge slabs of rock with shallow soils on top, or merely pockets or soil in cracks and depressions. Some plants love it here, and maybe in cities, too. Source

Imagine you have an urban or suburban space to re-design, replant or restore, ask yourself “is there as physical/biological landscape nearby in the “non-human” environment that is analogous to this place?” If so, it follows that maybe the plants that survive and thrive in that “reference ecosystem” might do well planted in this area. Examples given at the symposium included: Cliffs are a “natural” reference for tall concrete buildings; canyons are analogous to streets lined with skyscrapers; rooftops bear a similarity to islands (without the water). Other examples included alvar as a reference for pavement or container gardens; clay ravine bluffs as a reference for, well, the greater Toronto area’s clayey, saturated soils

In the first part of the symposium, each speaker in turn discussed a reference ecosystem in depth, including its distribution, physical characteristics and unique flora and fauna. Below, I’ll summarize my “big takeaway” notes from each speaker. (this isn’t necessarily what they were saying, but what their talk made me think of, or what stuck in my head)

Stefan Weber: Clay Bluffs

should ecological restoration focus on a few rare species or engineering ecosystems to maximize/optimize biodiversity?
demand for native seed leads to pressure on wild populations, but also mean an opportunity for green business (seed orchards) while also increasing genetic variation and ecosystem function
clay bluffs (along 16 Mile Creek in Oakville) have a “hanging prairie” near the top of the slope, where erosion causes disturbance that maintains an otherwise unusual community (typically in sandy soils with fire as disturbance)
I need to go for a hike in Lions Club Park this year

Will Van Hemessen: Prairies

current climate in Ontario favors forests over prairie, and even more so with climate change projections
you can grow prairie plants in sandy gravely construction fill, but is it really restoration if there was never a prairie there in the first place? (or are you building a novel ecosystem? is that a bad thing?)
earthworms (not native to North America) may actually help maintain prairies by selectively eating non-prairie seeds (accidental bio-control?)

Niel Turnbull: Rock Gardens

Montreal Botanical garden is world class, partly because it is laid out for constant discovery
take flat rock slabs, lay them on it short side, stacked in a row (like plates in the dishwasher) and you can grow a beautiful rock garden in that
rock gardens should be about 4 hours of maintenance per year, a bit of weeding, no watering or pruning required

Albert Garofalo: Alvar

60% of all the world’s remaining alvars are in Ontario
it is possible to “reverse the Ecological Land Classification system” (ELC is a tool ecologists use to catalog ecosystems in Ontario) to find a reference ecosystem and generate a potentially suitable plant list for an urban/suburban site
alvars can benefit from burning just as prairies do

Doug Larson: Cliffs

Humans evolved in cliffs and have continued to build increasingly sophisticated cliff-like structures (castles, skyscrapers)
Many of the most common “weedy” plants and animals that live alongside humans originated (and still have wild populations and sister species) in cliffs: Pigeons, Dandelions etc. etc.
Thus, an hypothesis: plants that like to live in cliffs should do well in cities. Try it out for yourself, some species will likely fail, but others may succeed in a big way!

Wild Columbine growing in a container on my balcony. It makes hundreds of tiny black seeds every year, and I just let them fall where they may!

After the talks, we spent the afternoon in small groups applying the reference ecosystem concept to actual examples around Toronto. It is a really interested idea, and fun to apply. My personal feeling about it is that this is a great way to come up with ideas of what to plant, and how to think of urban places as densely inhabited variations of “natural” environments. In the end, it all comes down to this: will the plants actually grow? To find that out, ideas are just the beginning. What we really need to do is start trying, failing, collecting data and then getting better and better at growing native plants in cities.

If I have my way, there will be so much self reproducing Wild Columbine in Toronto by 2030 that people will start considering it a weed. By all accounts it should so exceedingly well in this landscape filled with constructed cliffs, grottos and alvars since it does so well in those reference ecosystems. Next step: start planting!