Hidden among all the houses and tall buildings in Toronto is a complex and beautiful system of ravines and parks. There's so many of them, in fact, that they make up around 20% of the city area. To give you a comparison they're 30 times bigger than Central Park in New York City.
The ravines are a result of the ice age. Essentially thousands of years ago Toronto, as we know it today, was completely covered in ice and glaciers. As those glaciers melted, they carved out the land creating all the ravines and valleys we have today.
Today, the ravines are home to rivers and woodlands running along their banks. Trails wind between the trees for people to explore and hike. The ecosystems are also home to all sorts of plants and animals. Unfortunately, though, they're in serious danger.
According to a study by the University of Toronto this year, the city's green space is being majorly threatened by invasive species right now and if we aren't careful they'll be completely sterile, empty valleys in the next couple of decades.
The study found that unless we do something to intervene, the ravines that make up so much of our city, 20% to be exact, will disappear within our lifetime.
Invasive species are essentially like murder squads when it comes to our natural ravine systems. The weeds and trees get into the environment somehow and steal nutrients from the plants already there or sometimes even poison them with their sap, wiping them out completely.
This may seem like a perfectly natural process and just sort of nature's way of survival of the fittest, but humans play a role in it. One of the invasive species harming Toronto's ravines is the Norway Maple tree, which is regularly sold at garden centres.
By planting them on our own properties, humans have made the Norway Maple reproduce at an alarming rate. Now, it makes up almost half of the Toronto ravine plant life, which is concerning because its roots destroy the ground plants while it sap kills other species nearby too.
When this happens it creates erosions and landslides in the ravines and eventually, enough of this will lead to total desolation of Toronto's ravines. Beyond this, in the past companies and people regularly used the ravines as a dumping ground, literally turning it into a wasteland.
To fix this all, environmentalists in the city want to declare essentially a state of emergency. They want to warn the people of Toronto about Norway Maples and other invasive species and cut down the areas that have in infected and replant there. With the ravines already disappearing, they're hoping it's not too late.