We took a short walk along the pathway and stopped to take in this beautiful view – and the variety of grassland and tree species all around us.
Further into the park, we stopped by a cedar grove to admire more of the diversity of the Highland Creek path. Greg discussed the importance of wildlife habitat within a forested area, focussing on trees for nesting sites and food.
Halfway through the tour, we came upon a picturesque view of the creek and a mini-waterfall! Greg educated us on city bylaws with regards to stormwater management, which was especially interesting given the recent flooding Toronto and other major cities have experienced. In particular we learned about the role of willows during major storm events, and how their extensive root systems can help soak up excess water and also reduce soil erosion.
Next, Andrea pointed out a very tall white pine tree, which must have been at least 100 years old. She talked about their importance throughout Canadian history and how even today, many cough syrups contain active ingredients that can be naturally derived from them!
Andrea also talked about forest succession, and she showed us some early successional tree species such as poplar, willow, birch and black locust, which are able to establish themselves relatively quickly following disturbances to the forest.
Among the other tree species of the valley we saw the interesting leaf shapes of the horse chestnut and the thick canopies of the invasive Norway maples.
We discussed how the beautiful canopy of a Norway maple can offer many benefits: it sucks up CO2, shades us from sunburns, grows quickly and is tolerant of urban stresses, which makes it a pretty good street tree. But its heavy shade kills off nearly everything underneath it and its shallow root systems absorb all of the available water and nutrients. They also seed like crazy, reproducing at rates that can be hard to keep up with. The invasive maples can be easily identified by their exaggerated leaves and moustache-shaped seed keys.
Heading back towards the park entrance, we encountered five dying ash trees as a result of the Emerald Ash Borer, a shiny little green bug from Asia that arrived in North America on solid wood packing material carried in cargo ships and airplanes.
Here Andrea also talked about snags – dead or dying trees that are left standing - and how they are exceptionally healthy for an urban forest. They can host thousands of species of bugs, and create habitat for woodpeckers and small songbirds. In an urban forest we tend to cut down dead trees for safety, but here fallen branches give habitat to wildlife, and snags that are left standing can give a lot back.
By the end of the tour we were all better acquainted with the surrounding landscapes, and ready to share our new-found knowledge with our friends and families. The next tour is the Edible Tree Tour on August 24 – will we see you there?
Our Tree Tours are supported by Ontario Power Generation's Biodiversity Program, York Region and the Ontario Trillium Foundation.