THE LEAFLET

What is canopy cover and why does the City track it?
To better understand canopy cover, see the images below. The raw image on top shows trees as green circles on the landscape. The modified one on the bottom is the same image showing the same trees with a computer-generated overlay representing their crowns – or canopies. Analysts use these overlays and other images to refine them, add them all up, and divide by the total area of the City’s landmass to calculate how much area is covered – or shaded by – trees.

Since 2000, Washington DC has measured its canopy to know: a) if its laws and policies related to tree preservation are succeeding, and b) to determine if it is attaining the City’s 40% Canopy Goal, memorialized in the  2013 Sustainability Plan.

What do these and prior results show?
Starting in 2006, DC’s canopy covered 36% of the City. Over the following two measurement periods (2011 and 2015), canopy coverage increased to 38%, but the last measurement taken in 2020 showed a one point decline to 37%. While the good news is that we did not lose all of the hard-fought gains from 2006 to 2015, we still are down one percent, which may seem small – but in tree terms, it’s a lot. To use a landmark we all know, one percent is equal to a land area approximately the size of the National Mall; that is a lot of trees and a lot of shade.

What else does the canopy study reveal?
Over the next several months, Casey Trees will showcase more details about the City’s study in our weekly newsletter Leaflet, including information about impacts to Wards, ANC’s, public vs. private lands, and – where the canopy has increased despite the overall decline. The main message is that after years of hard-fought gains and the planting of thousands of trees each year by partners like DC’s Urban Forestry Division, Casey Trees, and others, we have regrettably taken a step backward.

What can you do?
Increasing the tree canopy is a challenging thing. A large tree is removed in an instant and replaced in a generation. We have all lamented the loss of a large tree in our park or neighborhood and its cooling shade, beauty, how it shelters us from the rain, but we will not give up the fight.

We can regain what was lost as there is still plenty of land to plant more trees, but additional steps must be taken to preserve and protect what we have. Speak to your ANC leader, your Council Member, Mayor Bowser. Tell them that trees are essential to you and your family and friends’ quality of life, to your neighborhood, your community, and the environment. Finally, tell them to support our City’s tree protection legislation expansions.

Perhaps most important – lead by example. Plant a tree on your property and encourage your neighbors to do the same. Attaining and maintaining a greener, healthier Washington DC is a group effort that can only be achieved if we all work together.

To find out how you can plant a tree on your property for free and advocate for stronger tree protections to make a difference – go to caseytrees.org and thank you for your support.