LEARNING TO LOVE THE RAVINES
Some of the main issues affecting a potential ravine strategy:
The origins
Ravines in Toronto were formed thousands of years ago, after glaciers compressed the land, and water later wore away the soil. The major ravines and river systems in the GTA flow from the Oak Ridges Moraine into Lake Ontario.
Three hundred years ago, the land in and around Toronto was unspoiled wilderness. But when settlers started clearing land for farming, trees were felled and fields planted with crops, which transformed the natural environment. There was a period during the last 50 to 100 years — the dawn of our urbanity — where ravines and nature were viewed as places for our refuse.
The advantages
The benefits of having these spaces as protected wilderness areas now are almost inexhaustible, and society has finally recognized that, experts say.
One major benefit is flood protection, which became evident after Hurricane Hazel in 1954. After that storm and flooding, the province gave what is now the Toronto and Region Conservation Authority (TRCA) the power to acquire ravine lands and other greenspace for flood protection uses such as dams.
The key data
Prof. Sandy M. Smith of the U of T’s faculty of forestry, says the city’s ravine strategy must include ongoing, evidence-based measurements of the “ecological integrity” of ravines.
“Right off you need to look at tree species,” Smith says, arguing that trees are the “underpinning” of ravines by keeping soil on slopes, and preventing soil from flooding into waterways. The key is gathering data on which trees are in ravines, and which ones should be there, Smith says.
The invaders
Smith points to a 1977 report a student in her department recently tracked down about the Rosedale ravine system. The report shows that nearly 40 years ago, Norway maples made up 10 per cent of this ravine system. Now the tree is found in 40 per cent of that area.
“Norway isn’t native, but rather a new species that came here in the 1960s and 1970s,” Smith says. “At that time 10 per cent of the ravine sites had Norway maple. Today it’s 40 per cent, and the number of native species are slipping away, like beeches and ash. So we know there are threats to the integrity of ravines, so we would want to measure that — which trees are native, which aren’t.” Smith says the city, TRCA, students and experts from fields like hers should play key roles in monitoring ravine health.
The average Joe
Jason Ramsay-Brown, the author of the book on ravines, sees merit in average citizens playing a role in the ravine strategy. “There are already a host of opportunities for the public to become involved in preserving, protecting and enhancing ravines, whether through garbage cleanups, tree plantings, invasive weed pulls, and citizen science work such as water quality and soil sampling,” Ramsay-Brown says.
“There are tons of opportunities for people to help build the inventory of ecological information required to be able to measure progress, success and failure and say, ‘How are we affecting these areas?’ ”
The inequities
L. Anders Sandberg, a professor in York University’s faculty of environmental studies, says any efforts stemming from the ravine strategy must be approached through the lens of equity. “I’m thinking of folks who helped restore (the Brick Works, near Rosedale). School kids and youngsters from different parts of the city, sometimes not so privileged areas, did volunteer work to restore it. Why isn’t money pumped into other areas?
“Look at the Black Creek watershed, which empties into the Humber. That particular watershed is probably the most degraded and polluted in the whole city of Toronto. At the same time (nearby) Jane and Finch is of course known as a very marginalized area. Is there a relationship here? Why is that?”