Planting trees in highway interchanges helps sequester CO2 and beautify Tennessee. These are important benefits, but the impact of our work goes far beyond this. We define our impact in the context of triple bottom line accounting: people, planet and profits. Reforesting and landscaping interstate interchanges positively impacts the triple bottom line, offering benefits for the whole community including the following:
Planet: Environmental Impacts
Climate change is one of the biggest threats to our planet’s ecosystem. According to NASA by planting half a trillion trees worldwide, 205 gigatons of carbon could be captured, reducing atmospheric carbon by 25%. Achieving this depends on planting nearly every area that is not agricultural crop land or urban area. Highway interchanges represent a significant land area for planting trees. Our long-term goal is to plan 75% of the 373 interchanges in Tennessee, an estimated 3,497 acres, which would result in over 4 million trees planted and would offset nearly 3.3 billion pounds of CO2.
In addition to sequestering CO2, forests filter out other air pollution (including Sulphur dioxide, Nitrogen dioxide, ozone, carbon monoxide and particulate matter) thereby reducing the health impacts from those sources.
Trees also filter out and reduce water pollution, as well as reduce flooding by channeling rainwater into the ground through the root systems and then reabsorbing a portion of the water only to seed the sky with moisture. These benefits positively impact the entire downstream community.
Planting trees provides many additional benefits when planted in a highway interchange. These include moderating temperatures, reducing noise pollution, and providing beautification.
Due to the proximity to roadways, we do not plant trees in interchanges to attract wildlife, however there are many benefits for wildlife. Forested interchanges provide habitat for migrating birds, help pollinators, and more.
Profit: Economic Impacts
The space in interstate interchanges is largely not utilized, and maintaining these areas represents a cost to taxpayers. The Tennessee Department of Transportation (TDOT) spends $5.2 million annually on maintaining these sites, including mowing. This is costly and mowing is a source of carbon and other pollution. Planting trees in interchanges may reduce or eliminate the need for mowing saving money.
The value and costs savings from planting trees was measured in a major city in the southeast. It was determined that the forest in and around the city eliminated approximately 19 million pounds of air pollution at a value of $46 million. And stormwater retention capacity of the forest was valued at $2.36 billion.
Trees may also provide economic benefits and cost savings for businesses and the community. Some of this is a result of the beautification trees provide. For example, shoppers are willing to pay as much as 10% more for products and services if trees line the street where the business exists. Employees who work in forested areas show higher productivity and less stress as they soak in the green during lunch and breaks. Communities that have more trees and community forests have lower crime rates.
People: Health, Community, and Social Impacts
The CDC estimates that – with no change in regulatory controls or population characteristics - there may be 1,000 to 4,300 additional premature deaths nationally per year by 2050 from combined ozone and particle health effects. Planting trees in highway interchanges could help reduce these pollutants and thereby help reduce asthma and lung disease, heart attack, and premature deaths.
Climate change has a disproportionate impact on communities of color and lower income. “Oxfam estimates that the world’s richest 10 percent of people have carbon footprints that are 60 times higher as the poorest 10 percent.” - United Nations University. Since the impact of CO2 on our atmosphere is not a local issue, wherever sequestration (reforestation) projects occur they have the potential to help those that are most impacted by climate change.
There is a correlation between the average numbers of hours residents get of physical activity and the community trees. For example, people get outdoors more frequently when the area is greener. This in turn correlates with better health and wellbeing.
Especially during the pandemic, Green Interchange tree planting events provide an outdoor activity that can help with team building, leadership, and community relations. The organization and events also provide education for the community including the value of and proper planting and care for trees.