Ecological Integrity of Toronto's Ravines - How to save a threatened urban ecosystem?


(Thea Silver) #1

The Toronto ravines are one of the world’s largest ‘urban ecosystems’. They cover 17% of Toronto (for a total area of over 11,000 hectares!) and, in addition to offering 2.8 million citizens the opportunity to enjoy nature, they are the primary source of habitat for Toronto’s terrestrial biodiversity and provide billions of dollars’ worth of ecosystem services.

On Friday Nov 4th, the final report of the Toronto Ravines Study: 1977-2017, was released - and the news was not good. The report was profiled by CBC news/radio, and you can also learn more on the Toronto Ravine Study website.

According to the study, the ecological integrity of Toronto’s ravines is in serious decline. Norway Maple, an invasive tree species, has increased its tree canopy cover from about 10 per cent in 1970s to about 40 per cent in 2017. Invasive herbaceous plants, such as Japanese knotweed, garlic mustard and dog-strangling vine, are now found in more than 95 per cent of the forest floor surveyed by researchers. Toronto’s native biodiversity is fast disappearing. Toronto residents should be concerned about the decline of the city’s ravines because they benefit Toronto recreationally, economically and ecologically.

So is all lost?

The report stresses that if widespread, science-based action is taken soon, then it is possible that the Toronto ravines can be restored to a healthy state, and it makes recommendations to accelerate the process of integrating science into ravine policy, practice and community engagement.

It also highlights a new, innovative effort launched recently in New York City which could provide an impressive model for Toronto to follow. Established through an ambitious public-private partnership, the New York Natural Areas Conservancy exists to restore and conserve the green and blue spaces of New York City in order to enhance the lives of all New Yorkers. For an area roughly half the size of Toronto’s ravines, NYC has budgeted $385 million over 25 years to enable a massive science-based program to inventory, restore and steward its natural areas. The report suggests that if Toronto modeled that approach, it could restore its ravines within 10-20 years, making it one of the world’s greatest urban ecosystems.

So could such an approach work here? What would it take? And what work is happening now - either here or elsewhere - to help us get to that goal?