This past month, we have been playing around with i-Tree Canopy, an open access web tool in which you can highlight an area in Google Maps and view hundreds of close up images, assessing whether you are viewing a tree, other vegetation, or anything else. The tool calculates the overall tree canopy for the selected region, giving us a good idea of how well we are fairing on our way to the city’s overall goal of 35% tree canopy coverage.
We broke our categories down so that any point is defined as a tree (T), non tree (NT), or grass and other vegetation (G), but you can choose to break it down further into any category you like, or just stick with tree and non tree. This is a fantastic tool, although we will note that some images were difficult to decipher, and smaller trees may have been missed and categorized at “other vegetation” instead.
Here’s an idea of how things are going in within the Hamilton Urban Boundary:
This includes the forested escarpment other more rural greenspaces, and does not accurately reflect what we see in the built up city. It is unclear what boundaries are used to define our city’s goals and progress. The chart in the top right corner shows the spread between our three categories and the standard error: the Hamilton Urban Boundary has a tree cover of 26.1%, plus or minus 1.39%.
We wanted to compare our focal neighbourhoods to the rest of the city. As we mostly focus our efforts on densely populated areas with historically poor air quality, we know that low tree coverage is an issue we want to work with the city and neighbours to tackle.
Surprisingly low canopy coverage here at 11.5%, but we see that the “other vegetation” category is high (32.9%), which tells us that there is plenty of room to plant. The highway may have skewed the results, as the Google images assessed using i-Tree cannot tell us the whole story, and all we see is the bridge and not what may be underneath.
With our office situated in Beasley, we already knew that the tree coverage was low, but we were still surprised at these results. With only 10.9% tree cover and 7.87% “other vegetation”, any planting effort in the neighbourhood will require some sort of depaving project.
Last year, Trees Please inventoried a number of trees in the Centre Mall parking lots, but these are still very small for the time being. With a canopy cover of 14.4% and other vegetation only 12.1%, this is another area that will require more depaving to reach the city’s 35% or higher goal.
This neighbourhood has many large yards with very few trees, but the Red Hill Valley and Hillcrest Park help bump up the canopy to 18.8%, the highest in all our focal areas. With 23.7% other vegetation, there is still some good room to plant, and Trees Please will be focusing efforts on direct contact with residents to encourage planting in their yards. Look out for a free tree giveaway later this year, McQuesten folks!
We are looking forward to getting some on-the-ground information about this neighbourhood in 2018, but this satellite analysis shows a tree cover of 16.3%, with other vegetation at 22.9%. This neighbourhood boasts some beautiful parks along the waterfront helping to up the canopy coverage, but with smaller urban yards, the coverage where people actually live and work is still low.
Our second new neighbourhood for 2018, Sherman also has a large proportion of paved surfaces, with a low canopy at 15.7%, and 10.0% other vegetation.
You can try out this tool for yourself! Visit canopy.itreetools.org/ and define your study area. For our analyses, we completed 750 sampling points for each neighbourhood, and 1000 for the overall city. i-Tree recommends 500-1000 points for better results. Help us boost that canopy by planting trees in your yards and coming out to our tree plantings in 2018. Encourage your neighbourhood schools to look into planting trees in their yards (we can help!), and request a free street tree through the city for in front of your home. And don’t forget to join Trees Please in Sherman and the North End this summer for our neighbourhood inventories!