The environmental benefits of trees can also put some extra green in your wallet
Carbon sequestration, storm water, energy savings, the Green Cities Initiative, and the dangers of invasive species: these are all hot buzzwords in sustainability, and they can be excellent examples of why trees matter.
“We know trees are worth energy savings, and that’s a big deal right now,” says Pamela Bennett, Ohio State University Extension master gardener volunteer coordinator. “Green Cities and LEED certification, becoming more sustainable. Your community is probably very focused on storm water remediation; it may have even been mandated that you take care of your storm water. Invasive species is another key topic we need to address.”
Pamela uses a software called i-Tree and the National Tree Benefit Calculator to quantify the value of these hard-to-measure categories. The i-Tree suite of tools was developed by the USDA National Forest Service and several collaborators and is available for download from the i-Tree website. The National Tree Benefits Calculator is another tool designed to be a simple, accessible tool to estimate the environmental and economic value trees provide on an annual basis. Just enter your zip code and it will provide tree values in your area so you can see how much your trees are worth in dollars and cents.
The environmental benefits and economic benefits go hand-in-hand. Trees are especially important in urban areas because of their effect on stormwater runoff, Pamela says. Because overworked sewer systems in many communities can’t handle the load of a large rainstorm and expanses of paved roads, parking lots and other impervious surfaces, rainfall washes quickly into streams and rivers, carrying silt, fertilizers, pollutants and even sewage with it. Large shade trees act as mini-reservoirs, controlling runoff at the source, reducing and sometimes eliminating those problems. Trees intercept rain on leaves, branches and bark, and infiltration is improved through the tree’s root system. The pin oak in Washington will eliminate 14,565 gallons of stormwater runoff this year.
Trees also increase property value while saving the property owner energy costs. “Realtors have always known trees out front of a home increase the ‘curb appeal’ but were never able to say how much,” Pamela says. “Now we know home buyers are willing to pay 3 to 7 percent more for a home with ample trees versus one with little or no trees.”
Trees modify climate and conserve building energy use in three ways, Pamela says. First, shading reduces the amount of heat absorbed and stored by buildings. Second, evapotranspiration converts liquid water to water vapor and cools the air by using solar energy that would otherwise result in heating of the air. Third, tree canopies slow down winds. This helps reduce the amount of heat lost from a home, especially from areas where conductivity is higher, like glass windows. The same 36-inch pin oak mentioned above will conserve 351 kilowatt/hours of electricity for cooling and reduce the consumption of natural gas by 9 therms. That’s a savings of $36.20.
Carbon sequestration is another big sustainability buzzword and the single pin oak will reduce atmospheric carbon by 1,022 pounds. And the savings keep on growing as the tree does, which is why it’s important to care for existing trees, rather than just replacing them with newer, less mature trees.
How significant is this number? According to Pamela, most car owners in an average vehicle such as a mid-sized sedan drive 12,000 miles, generating about 11,000 pounds of CO2 every year. Trees reduce carbon in two ways: they sequester in their roots, trunks, stems and leaves while they grow and in wood after they’re harvested. Second, trees near buildings can reduce heating and cooling demands, reducing emissions associated with power production.
Invasive species are another hot topic, especially in states that have experienced the emerald ash borer. Pamela says her i-Tree studies have shown a disturbing lack of diversity of our tree canopy. “When you see it on paper, it really hits you in the face that we have an awful lot of ash trees or maples, or both, and we need to do a better job of planning,” she says. “Looking at invasive species wasn’t our goal when we started the tree surveys, but it rose to the top after we looked at it.”
If you’re looking for the best tree for your area, check with your state or city’s division of forestry. They’ll have all kinds of information on planting in your climate and soil profile.