Pilot Projects

Spring/Summer 2019: Japanese Knotweed Study, Park and Moore Ravine – Private and Public Land

Japanese Knotweed is invading Toronto’s ravine system, which could have harsh effects on the stability of the stream banks and ecosystems within the ravines. It is currently abundant in Moore Park Ravine, Park Drive Reservation Lands and Vale of Avoca (mapped in 2018). Due to the connectivity of Toronto’s ravine system, and the fact Japanese Knotweed can easily spread by its own fragments being carried downstream, it is likely a problem throughout most if not all of Toronto’s ravines.

This project started mid-April, where 260 letters were delivered to residents in Moore Park Ravine and Park Drive Reservation. The informative letter contained a description of the project, a description of Japanese Knotweed and how to identify it, as well as a request for access to the residents’ property for assessment. Some properties were targeted since they had large amounts of Japanese Knotweed visible from the paths in the ravine.

In May 2019, the mapping started. In conjunction with this, a second project to test Japanese Knotweed eradication methods was started. Both these projects required participation from private residents in the ravine. The outreach to private property owners was a key component as this allowed mapping of all Japanese Knotweed in the ravine, as Japanese Knotweed knows no boundaries, ones such as private land versus public land.

In the two ravines (Moore Park and Park Reservation Drive), there was a total of 4,173.5 m2 of Japanese Knotweed mapped. Which is equivalent to three and a half-sized Olympic pools!

Most of the Japanese Knotweed in each ravine grew close to water, which aligns with the current literature on growth patterns of the plant in riparian areas and along waterways, shown in the map below.

Japnese Knotweed was found in the ravine and usually by water.

An area was coined the “hot spot” in Park Reservation Drive, due to it having a large area of Japanese Knotweed on private land, and possibly marked for future studies on private land. Refer to the map below.


In both ravines, the majority of Japanese Knotweed was on public land, 62% and 38% of Japanese Knotweed was on private property, which mirrors the distribution of ravine property (land), where 60% of it is on public land and 40% of it is private property.

Distribution of Japanese Knotweed by private versus public land.


A very large patch of Japanese Knotweed creating a “wall” along the path in Park Reservation Drive. This large patch measures 500m2. It dominated this part of the ravine, creating a monoculture (no other vegetation grows with it).
The blue represents the large patch of Japanese Knotweed pictured above (500m2) which is alongside a public walking path, the red shows Japanese Knotweed mapped on private property.

Spring 2018: Mapping Japanese Knotweed in the Vale of Avoca


Credit Colin Stark

(Photo credit: Colin Stark)

Team members Alex Stepniak (left) and Eric Davies (right) working in the ravine.

2016 – now: Mapping & seed forecasting old-growth native trees throughout Toronto’s ravine system

Toronto Trails 36x48 as of June 2017(Map credit: Mary Grunstra)

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