American Forests, which is a US non-profit conservation organization, publishes something that they call a Tree Equity Score. What it effectively does is map tree cover across US cities. You can explore what that looks like, here. The score considers things like tree canopy, population density, income, race, as well as many other factors, and then produces a single score from 0 to 100. A score of 100 means that a neighborhood has achieved “Tree Equity.”
There is seemingly a lot that you can glean from this score. For one, American Forests have found that income and race tend to correlate with tree canopy. Lower income neighborhoods tend to have less of it and rich neighborhoods tend to have more of it. You can start to see what that looks like in the Instagram post embedded at the top of this post. If it isn’t showing up, click here.
But the other thing that is clear from these images is that rich people tend to consume more space. The richer tree-canopied neighborhoods appear to be less dense. The lots are bigger. And there are instances where the homes look to be adjacent to some large contiguous green spaces. This, of course, is a natural market outcome.
The Tree Equity Score tries to correct for this in its methodology. If a neighborhood’s population density is very low (less than 2,000 people per km2), then it gets a higher tree canopy adjustment factor. It should have more trees. Conversely, if a neighborhood’s population density is high (over 8,000 people per km2), then it’s acceptable for there to be less trees (lower adjustment factor).
That said, it would be interesting to see a direct comparison of two neighborhoods — one rich and one poor — that have the exact same population densities and overall built form. I think that would speak volumes about tree inequity. I am also very curious about the global relationship between density and household incomes.
If any of you have a good source, please share it in the comment section below.