What Tree Should Be Planted?
The assignment was to find the best choice for a new planting of trees. The site evaluation included above- and below-ground inspection. The tree species would be located in an urban area with impervious surfaces including roads, parking lots and buildings with many businesses. Daily human foot traffic would require planning for smooth sidewalks. The settling of walking surfaces is influenced by the trees root system which is affected by the soil characteristics, freezing and thawing, installation and the age of the tree. Overhead many utility lines and poles make tree placement important. Tree maintenance needed to be included with desirable tree attributes.
Trees in our urban areas are on the job 24 hours every day working to provide services that benefit humans and the environment. Carefully chosen tree species can do a good job of producing oxygen, reducing airborne particulates, enhancing respiratory health, sequestering carbon, breaking cold winds, providing food and shelter for wildlife, reducing noise and glare, decreasing soil erosion and surface water runoff, creating microclimates, reducing energy costs, blocking sunlight, reducing soil temperatures, screening and defining space, increasing property values, reducing erosion and creating lasting impressions. Finding the best tree species for such a major undertaking calls for expert help.
Experts frequently study plants to determine the factors influencing growth. One research study was done in Raleigh by Steve Frank and Elsa Youngsteadt from North Carolina State University and Adam Dale from the University of Florida. The tree evaluated for planting in the stressful environment was the colorful red maple. Previous work concluded that an increase in air temperature and drought stress reduce the ideal growing conditions for trees and increase the abundance of scale insects. Pest damage and urban stress reduce tree health and longevity and also increase maintenance costs. The conclusion of the study indicated a site with 0 to 32% impervious surface was acceptable for the red maple. Other tree species were better choices if the impervious surface was greater than 32%. The amount of impervious surface predicts the abundance of pests and stress which reduce tree conditions.
Planting more than one variety of tree is a hard lesson to learn. Many communities have been affected by the loss of major plantings because they were struck by diseases, insect pests or unknown weakness. Bradford pears were standard trees in the 70s and 80s until they began to break apart. Photinia was used until a leaf spot disease began defoliating a majority of the trees. Leyland cypress was planted as a screen until bagworms started killing hundreds of trees. Planting a variety of trees in the community will benefit us as it is impossible to predict where the next issue will arise.
Choosing a tree variety to plant may seem like a very simple choice but making a careful thoughtful decision can assist in developing a more sustainable environment for generations to come.