In July 2007, they planted 30,000 trees in Downsview Park in an effort to transform this former military base into a landmark. When I visited during the summer of 2010, things were shaping up at the park. Trails were running through a tiny forest with a few surprisingly big trees (located by the parking lot in the middle of the park). I noticed the promising shape of an artificial lake far away in the southwest part of the site.
The park has offered many events over the last few years. You could use their Canada Day activities as an excuse to visit the little forest. Check their website for the current line-up of activities: during the summer 2011, they offer movies in the parks on Friday nights. In the past, they’ve offered Fallfest, Winterfest, Family Day, and the indoor midway of Springfest (during March Break).