Tree Canopy – A Tool To Build Climate Resilience

Author: Lisa Johnson, Horticulture Educator

County Office of Energy and Climate Change has created a Climate Action Plan to cut carbon emissions in half within the next decade. One of the ways to help achieve this goal is to protect existing trees and increase tree canopy cover in the county. The non-profit American Forests recommends a minimum canopy cover of 30% in communities.

Canopy cover is an important tool for building climate resilience in communities. Trees absorb airborne carbon in greenhouse gases such as carbon dioxide, ozone, and carbon monoxide from the burning of coal and natural gas as well as from vehicle exhaust into their leaves. In this way, they help reduce the gases that fuel climate change and increase air quality. Better air quality benefits health, especially in areas prone to smog and Ozone Alert Days. Trees also help to mitigate flooding by slowing down raindrops and absorbing excess rainwater.

Shade from trees reduces the energy needed to cool buildings in the summertime. In addition, the cool shade that trees provide helps to reduce temperatures in heat islands that form in urban areas with high levels of concrete and asphalt. Heat is a killer: in 2018, there were 1,012 heat-related deaths in the U.S; this jumped to 1,577 in 2021.

Various communities across Dane County lost an average of 12% of their canopy cover from 2010 to 2017, with some communities experiencing losses of up to 38%. Areas across the county with the largest percentage decrease of canopy coverage are areas with multi-family housing, single-family or two-family residential housing, and recreational spaces such as parks.

Tree losses are primarily due to insects such as the emerald ash borer and tree diseases. However, trees stressed by drought, heat, unpredictable severe temperature swings in spring and fall, severe winter cold, and storm damage are more vulnerable to insect and disease damage. Ongoing development policies that do not prioritize tree maintenance and preservation also play a role.

The Tree Canopy Working Group’s mission is to maintain, protect, and expand public and private tree canopy across Dane County with a focus on making sure that canopy is equitably distributed. The Working Group is currently identifying under-resourced communities that have high levels of canopy loss or historical lack of investment in tree canopy (due to redlining and other factors) in which to hold tree planting programs. Communities that experience high social vulnerability, high percentage canopy change or historically low canopy cover, higher than average surface temperatures in summer, high levels of impervious surfaces, and housing primarily under public ownership or multifamily housing would benefit most from tree planting programs. The Working Group focuses on neighborhoods meeting these conditions as priority areas, and partnering with neighborhood leaders, local elected officials, volunteer groups, and non-profit organizations to plant donated trees in public and private spaces.

For more information, visit https://daneclimateaction.org/Initiatives/Tree-Canopy. If you are interested in volunteering at planting projects or applying for a planting project for your neighborhood, contact Askay.Melanie@countyofdane.com.