By Jane McKinley, McK Designs
As a member of the Cape Charles Tree Advisory Board (TAB), I am excited about the town’s interest in maintaining and enhancing its urban tree canopy. Through the TAB’s legwork and commitment, we are now ready to submit the application to become a Tree City USA under the auspices of the Arbor Day Foundation. In this series of ongoing articles, you will learn about the benefits of trees, how to select and plant a tree, town guidelines for trees in the historic district, and what trees are well suited for a residential space on Virginia’s Eastern Shore.
If you are interested in learning more about the mission of the Tree Advisory Board or would like to obtain landscape design services, you are welcome to contact me at firstname.lastname@example.org.
There are no two ways about it – trees are good! They reduce air pollution, provide shade and cooling and slow down stormwater runoff. They support wildlife, provide health benefits, and add value to the individual homeowner and the community. In this first in a series of articles, we will explore the beneficial life functions of trees and the many ways they add value to our lives.
Trees are Good for the Environment
Trees are good for the environment in many ways. One of the biggest ways that trees impact the environment is through the reduction of air pollution, a serious health threat that causes asthma, coughing, headaches, respiratory and heart disease, and cancer. This is done by removing harmful gases that contribute to smog, acid rain, and the greenhouse effect, a proven contributor to climate change. Trees “breath in” these gases, through their leaf stomata, which are like little pores in the leaf, and “exhale” life-giving oxygen. Two medium-sized, healthy trees can supply enough oxygen for a single person for a year, and an acre of forested land supplies four tons of oxygen, enough to meet the annual needs of 18 people.
They sequester (“lock up”) carbon dioxide in their roots, trunks, stems and leaves while they grow, and in wood products after they are harvested. Although it varies by size and type of tree, on average a single tree sequesters about 48 pounds of CO2 per year and, according to the US Department of Agriculture, one acre of forest absorbs six tons of carbon dioxide. It was reported (New York Times, July 7, 2020) that, in June, the Arctic fires released 59 million metric tons of planet-warming carbon dioxide, most of which came from releasing carbon sequestered in the trees. And the estimates of carbon released from the raging fires last year in the Amazon are around 140 million metric tons (as reported by NPR). Although a single tree does little to offset the annual carbon consumption of the average American (up to 21.8 tons), planting the right tree in a strategic location can be an important component of a multifaceted approach to reducing our individual carbon “footprints.”
Trees block the solar radiation that produces heat, helping to reduce the “heat island effect.” Trees near buildings can reduce heating and air conditioning demands which, in turn, not only saves money but reduces emissions associated with power production. These benefits are evidenced by a 2017 NOAA study which measured the amount of heat in the Washington DC area. It was discovered that, on a hot summer day, temperatures were as high as 102o in the areas where there were primarily buildings and concrete surfaces, whereas, in Rock Creek Park, a heavily treed area, temperatures were much cooler at 85 o.
Trees help to slow down stormwater runoff and create a natural filtration system that cleans the water, making it healthier for consumption and the overall environment. Runoff creates erosion, moves damaging chemicals from our streets into our bodies of water, and contains particulate matter from the burning of fossil fuels. Trees reduce this problem by intercepting and holding rain in their canopy, branches, and bark or lifting it out of the ground through their roots. In one day, a single large tree can lift up to 100 gallons of water out of the ground and discharge it into the air.
With all these beneficial attributes, the Town of Cape Charles is very lucky to have so many beautiful, majestic trees growing within its historic boundaries. In 2017 Town Council commissioned a group of Master Naturalist volunteers to update the inventory of trees in the town’s public spaces. A total of 2, 510 trees were identified, including 850 crepe myrtles. While crepe myrtles are one of our towns’ signature trees, there are many old, native trees that tower over 50 feet tall and provide cooling shade and habitat. One of these is the stately pecan tree growing behind the library. This tree looms over 60 feet tall with a trunk diameter of approximately 40 inches.
Wondering how much value this tree adds to our environment, I entered the tree’s location, trunk diameter and other information into the easy Tree Benefit Calculator sponsored by iTree, a website which offers a state-of-the-art, peer-reviewed software suite based on research from the USDA Forest Service. Although the site states that the benefits are estimated and are meant for guidance only, it helps to give an understanding of the environmental impact of an individual tree. Results of this search indicate that, in a single year, this tree sequesters 550.47 lbs of carbon (CO2 equivalent), intercepts 5,890.87 gallons of rainfall and prevents 86.66 gallons of stormwater runoff. The calculator also provides an estimate of the amount of carbon monoxide, ozone and other harmful gasses that are removed each year.
Trees are Good for Wildlife
Trees are good for wildlife, supporting it through all stages of a tree’s life. When mature they are used for food, shelter, and sites for reproduction. Many animals also use trees for resting, nesting and for places from which to hunt or capture prey. During times of extreme heat or precipitation, animals can seek shade and shelter under the trees’ canopy.
Standing dead and dying trees, called “snags,” are just as important. Birds, small mammals, and other wildlife use them for nests, nurseries, storage areas, foraging, roosting, and perching. Live trees with snag-like features, such as crevices and dead branches can provide similar wildlife value. Snags occurring along streams and shorelines eventually fall into the water, adding important woody debris to aquatic habitat. Snags enhance local natural areas by attracting wildlife species that may not otherwise be found there.
And finally, decaying logs from dead trees store carbon, fix nitrogen in the soil, retain moisture and nutrients that aid in new plant growth and support wildlife and soil organisms such as earthworms, beetles, and other insects. I am reminded of a majestic pileated woodpecker that visited for weeks on end to feast from a fallen tree in my yard’s natural area. What a delight it was to watch!
Trees are Good for Health
In addition to cleaning the air and water, trees are good for health in other ways. Research has shown that increased green space has been linked with decreased strain and improved health outcomes and immune responses. When given an opportunity to experience a tranquil forest scene, the stress of sustained concentration is lessened, resulting in higher student and employee performance levels. In research performed by Dr. Roger Ulrich of Texas A&M University, visual exposure to settings with trees produced significant recovery in high blood pressure and muscle tension within only a few minutes.
Trees are Good for the Homeowner
In addition to being a beautiful addition to one’s landscape, trees increase home values and help to save on heating and cooling costs. Healthy mature trees have been shown to improve overall property values by up to 10% and, when located in the front of the house, by up to 15%. Jim McGlone, Urban Forest Conservationist, recently commented on a beautiful shade tree that his neighbor removed. He noted that “this guy just spent $2,000 to cut down a tree that added $3,000 to his property value!”
Strategically placed trees can increase home energy efficiency. According to the USDA Forest Service, trees properly placed around homes can reduce air conditioning needs by 30% and can save 20–50% in energy used for heating. Planting a deciduous tree on the west or south side of a home will provide cooling shade in the summer and will allow warming solar energy to enter the home in the winter. Conversely, planting an evergreen tree on the north side protects it from chilling winter winds.
When I used this tool to assess the value of the 31” pecan tree overhanging my back yard, I learned a lot! First of all, to determine the diameter, measure the circumference and divide it by 3. I learned that my pecan tree provides overall benefits of $280 per year. It will intercept 11,964 gallons of stormwater runoff this year, will conserve 257 kilowatt hours of electricity for cooling and will reduce atmospheric carbon by 1,146 pounds.
And, of course, it provides a plethora of delicious pecans in the fall!
Trees are good for the Community
A tree-filled community has increased income, jobs, worker productivity and customers. By controlling erosion and reducing urban runoff, trees help communities to save money on storm damage repair and on water storage costs. They help to reduce energy costs to the public by lowering temperatures in urban areas. Trees and the atmosphere they create raise the value of homes and attract businesses and tourism, thereby increasing tax revenue. Consumers have a 12% higher willingness to pay for goods and services in retail areas that have streetscape greening such as street trees and sidewalk gardens.
Trees encourage people to exercise and interact. By creating safe, shaded open spaces for children to play and adults to congregate, trees enrich our lives. They reduce stress by filtering unwanted noise and replacing it with bird songs and rustling leaves. And, not surprisingly, domestic abuse, including child abuse, is lower in homes near trees.
Take a Walk
So, next time you are walking through your yard, neighborhood or in town, take a moment to look up and thank all the lovely trees that improve our lives aesthetically, economically and spiritually. They give back so much and ask so little.