Credit: Priya Jaishanker
Selecting Diverse Trees for Sustainability of the Urban Environment
Maximize your heating and cooling energy savings with careful tree selection. In this video, Robert Polomski, recommends that deciding what tree to plant is often the most important step in tree establishment. Trees should be well-suited to grow in the space they are planted. Inquire with your local Cooperative Extension office or Certified Arborist for suitable species to plant or visit local parks and arboretums to see what is growing well. Other considerations in tree selection are the mature size of the tree, type foliage and fruit, and fall color. Robert recommends planting a diversity of tree species so, in the event of disease or insect damage, all trees on the landscape will not be lost, stressing the importance of diversity to create strength in the landscape.
Identifying Strong, Structurally-Sound Trees
A structurally sound and healthy tree has a greater chance of surviving to maturity and withstanding environmental stressors than a tree with poor structure or health. This is also a tree that will realize the greatest energy savings in an urban setting. In this video, Robert Polomski demonstrates several important elements of an architecturally-sound tree. A few of the elements he stresses are a single, central leader/main trunk, evenly-spaced branches along the trunk, and no side-branches taller or larger in diameter than the central leader. The trunk and canopy features he describes can be used as a guideline for purchasing new trees or training (pruning) trees already established, or planted, in the landscape.
Tree Placement and Spacing for Energy Savings
Robert Polomski discusses the importance of tree selection and placement in maximizing energy savings from trees. Planting a variety of tree species, such as evergreen and deciduous, allows for not only an aesthetically pleasing landscape but also a more resilient landscape. For example, if one type of tree species dies in a diverse landscape planting, the entire landscape will not be affected as much as a landscape with the same species. Additionally, diverse species can be located in the landscape to maximize heating and cooling effects on structures, as well as providing a windbreak. The video also discusses the importance of maintaining (watering, fertilizing, and pruning) recently planted urban trees through their establishment period (often for the first 10-20 years) to maintain a canopy with a strong branching network .
Journey of a Nursery Tree from the Field to Balled and Burlapped
Robert Polomski discusses field-grown nursery tree production and methods nurseries use to grow structurally sound and healthy trees. Robert explains that, after harvest, most field-grown trees have their root balls wrapped in burlap and twine in preparation for transport and planting. Balled and burlapped trees are typically available from fall to spring.
Selecting a Balled and Burlapped Shade Tree at the Nursery
Selecting a healthy and structurally sound shade tree is an important step in establishing an urban tree that maximizes energy savings. Robert Polomski explains what to look for when selecting a field grown balled and burlapped landscape tree from a nursery, including trunk, canopy, and root indicators. A quality shade tree, for example, should contain: a single central leader/ trunk (tallest stem), evenly spaced side branches that make a uniformly shaped canopy, and a canopy that comprises approximately 60% of the total tree height (live crown ratio). Robert also recommends examining the nursery tree underneath its trunk and root ball wrappings, for example checking the trunk for any damage and identifying the root flare.
Selecting a Balled and Burlapped Ornamental Tree at the Nursery
Selecting a healthy and structurally sound, ornamental tree is an important step in establishing an urban tree that maximizes energy savings. Robert Polomski explains what to look for when selecting a field grown balled and burlapped ornamental landscape tree from a nursery, including trunk and canopy indicators. A quality ornamental tree, for example, should contain: a single central leader/ trunk (tallest stem), evenly spaced side branches that make a pyramidal-shaped canopy, and no co-dominant branches.
Selecting a Container-Grown Shade Tree at the Nursery
Selecting a healthy and structurally sound tree is an important step in establishing an urban tree that maximizes energy savings. Robert Polomski explains what to look for when selecting a container-grown landscape tree from a nursery, including trunk, canopy, and root indicators. He demonstrates the importance of selecting trees with a single central leader/main trunk, evenly-spaced branches along the trunk, and no side-branches taller or larger in diameter than the central leader. Robert also recommends examining the roots of container grown trees. At the nursery, gently remove the container from the root ball to inspect both structural and fine roots of the young tree. Roots at the perimeter of the container should be alive and healthy and several structural roots (large roots growing out from the base of the trunk) should be visible just below the soil surface. Container trees with severely circling, kinked, or girdling roots indicate a tree that has been in the container too long and are best avoided–unless the homeowner ameliorates these root defects at planting.
Robert Polomski is a Horticulturist and Adjunct Assistant Professor at Clemson University, Clemson, South Carolina
Videographer and Editor: Priya Jaishanker, Virginia Tech
Technical Directors: Holly Campbell, Adam Downing, Bill Hubbard, John Munsell, and Eric Wiseman (Cooperative Extension Service-Southern Region)
Also, special thanks to Clemson Cooperative ExtensionThis project was funded in part through a grant from the USDA Forest Service, awarded by the National Urban and Community Forestry Advisory Council