In the 1960s, Milwaukee's urban forest was devastated by Dutch elm disease, losing nearly 200,000 trees. While the public forest has recovered well, only 20 percent of Milwaukee's urban forest is on public land. This creates a wide disparity of canopy cover in Milwaukee, ranging from 1 percent to 42 percent. The city has an average canopy cover of about 16 percent, according to an Urban Ecological Analysis conducted by American Forests.

The American Forests study estimates that Milwaukee's existing urban forest reduces stormwater flow by up to 22 percent, and the city saves approximately $15.4 million by not having to build additional stormwater retention capacity. The study found that trees in Milwaukee reduce total stormwater runoff volume by 5.5 percent, and reduce peak flow by 9.4 percent.

In addition, Milwaukee's trees sequester approximately 1,677 tons of carbon annually. The current direct summer energy savings from Milwaukee's urban forest is valued at $650,000. American Forests estimates that adding one mature tree in the right location at each home (on the west or east side and shading the air conditioner) would boost that savings to more than $1.5 million a year.

Robert Skiera, retired City of Milwaukee Forester: I think we've just touched the tip of the iceberg as far as what trees do to us psychologically, and what they do to us environmentally, and what they do to us physically. How they can modify climates, and sequester carbon dioxide, clean the air, slow the waters. We hear this story so much but we need to keep it up because political management needs to hear that story so that they understand that trees pay and they don't cost.

The non-profit group Greening Milwaukee hopes to increase the city's canopy cover to 40 percent through the Adopt a Tree initiative, which provides free trees to private property owners, along with a planting care class for tree recipients. A 40 percent canopy will boost annual carbon dioxide sequestration to nearly 4,800 tons, according to American Forests.

existing 16% canopy	projected 40% canopy
These plots from the Milwaukee Urban Ecological Analysis show the city with an existing 16% canopy cover (left), and a projected 40% cover (right).