On Sunday 13th July about 15 of us were taken on another interesting tree walk through the ravine by John Routh, urban forester and leader of one of the city’s park stewardship groups.
We started at the St Clair subway entrance on Heath St West. Just behind the subway, John showed us some dying ash trees that have been attacked by the emerald ash borer. These trees will likely be removed by the city and replaced with new plantings of native trees. There are several examples of dying ash trees in the ravine.
John explained that the floor of the ravine was cleared when the subway was built under it in the early 1970s. No planting was done at that time, as some North York councillors still hoped that an expressway would be built. Thus most of the trees and bushes were self-seeded and many are non-native (there have been some later plantings). Two examples are Norway and Manitoba maples, which are common in the ravine. Norway maples were planted in city streets because they are salt and drought tolerant; however, they have many seeds and propagate fast, and their roots are close to the surface, inhibiting understorey growth and allowing erosion.
There are several species of oak in the ravine. Red and black oaks have pointed leaves, whereas bur and white oaks have rounded leaves. John also talked about the different types of birch, spruce and poplar (amongst them native trembling aspen, of which there are several groves in the park).
The ravine also contains many bushes: above you can see honeysuckle. In the photo below, John is standing beside dogwood red osier, a plant that has taken well in the wetter areas.
Sumac (see fruit below) is present in various places in the ravine. John pointed out that it is dioecious i.e. has both male and female plants, with the male having the flower and the female the fruit. We observed separate groups of male and female plants in different locations.
A common plant observed on the ground was plantain. John said the natives called it “white man’s foot” because it appeared wherever the pioneers walked.
We learned a lot more than my scattered notes above. I took more detailed notes; if anyone is interested in a copy, e-mail me at firstname.lastname@example.org
A big thanks once again to John for donating his valuable time and expertise to educate us in the natural treasures we possess in Cedarvale.