Trees Please Hamilton

Green Solutions to Air Pollution

Wrapping up our Lichen in the City project

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We’ve had a great time this summer and autumn introducing people to the colourful world of lichen existing quietly all around us! Thanks to support from the Royal Bank of Canada, we were able to host a series of workshops and neighbourhood inventories focused on our Trees Please neighbourhoods. Curious naturalists joined us for sessions in Bayfront Park and Gage Park to learn about the basic biology of these fascinating organisms, to check out a collection of samples from our nature sanctuaries, and to explore the parks for common lichen we can spot across Hamilton.



An abundance of lichen! Physcia millegrana (grey) and Candelaria concolor (yellow). The pinkish colour is lichen dying away, possibly due to its sensitivity.

At the end of these workshops, our new lichenologists participated in a neighbourhood lichen inventory to study abundance and its relation to air quality. By tracking two common species, Physcia millegrana and Candelaria concolor, we can monitor air quality over time. As lichen is very sensitive to air pollution and cannot survive in areas where concentrations are too high, the more lichen we see, the better.


We used a simple yet effective citizen science method developed by Dr. George Sorger from McMaster University. By inspecting a maple or an ash tree for these two species, we can get a sense of the abundance in an area compared to another. Report coming soon with the 2018 results!


This weekend, we got to take a field trip to the Amaolo Nature Sanctuary to compare the rural air quality with what we’ve been seeing in the city. There is a greater diversity out there, yet the impacts of the city and the 403 are still far-reaching.


Photo: Ute Schmid-Jones


Photo: Ute Schmid-Jones

We also introduced hundreds of kids to lichen and they are loving it! Now that they’ve spotting these organisms they’ve never previously noticed, they are hooked! We’ve thoroughly enjoyed their thoughtful questions and inspiring enthusiasm.


Now how to improve the results of these lichen surveys? By reducing air pollution and PLANTING TREES! Thanks to all the volunteers who joined in our community tree planting, and residents who participated in our free tree giveaway. By getting more trees into the ground throughout our city, we can help capture particulate matter and clean the air. Hopefully another inventory in a few years time will show the results of these efforts and more to improve the air quality in Hamilton.

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Lichen in the City is a project of Environment Hamilton and the Hamilton Naturalists’ Club, generously supported by the Royal Bank of Canada.

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Author: treespleasehamilton

A project of the Hamilton Naturalists' Club and Environment Hamilton. Funding by Ontario Trillium Foundation.

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