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Trees
Trees As Treasures
Understanding the Riches We Reap from Trees
Edith Makra, Community Trees Advocate, The Morton Arboretum

July 13, 2006

 

(photograph courtesy of Sue Auerbach)
  1. Research shows that shoppers in well-landscaped business districts are willing to pay up to 12% more for goods and services.
  2. A study showed that symptoms of Attention Deficit Hyperactivity Disorder in children were relieved after contact with nature. Children were better able to concentrate, complete tasks, and follow directions after playing in nature settings. The greener the setting, the more relief.
  3. Trees can significantly increase property values. In one tax case she cited, an oak tree was valued at $15,000 – or about 9% of the value of the property on which it stood. Another study concluded that a treed lot is worth up to 20% more than the same lot without trees.
  4. In one study, office workers without views of nature claimed 23% more incidences of illness than workers with views of nature.
  5. The net cooling effect of a healthy tree is equal to 10 room-size air conditions operating 20 hours a day.
  6. Trees properly placed around buildings as windbreaks can save up to 25% on winter heating costs.
  7. According to the US Forest Service, as few as three trees, property position around a home, can save an average Illinois household about 6.5% of annual heating and air conditioning costs.
  8. Effective tree shade on the east and west sides of a house can save up to 30% of annual air conditioning costs.
  9. Use of trees as an effective windbreak can save between 15% and 25% of annual heating costs.
  10. Tree canopy lessens the impact of rainfall, allowing moisture to seep into the ground rather than running off and eroding topsoil.
  11. Trees reduce noise pollution by absorbing noise.
  12. Tree-lined parking streets can reduce summer time asphalt temperatures by 35 degrees F. Shading is particularly important since paved areas absorb heat during the day and release it into the air during the day and at night.
  13. Trees, especially trees with rough leaves, trap particulate air pollution, such as pollen and dust. Trees also remove harmful gases from the air.
  14. Trees absorb carbon dioxide and generate oxygen through photosynthesis.
  15. In one study, hospital patients recovering from surgery who had a window view of trees required fewer pain relievers, experienced fewer complications, and left the hospital sooner than similar patients with a view of a wall.
  16. One study shows that drivers exposed to roadside natures scenes had a greater ability to cope with driving stress.
  17. A study concluded that on average the greener a girl’s view from her home, the better she concentrates and the better her self-discipline, enabling her to do better in school.
  18. Plants cool not only by shading, but by “evapotranspiration” – removing heat from the air by absorbing water from the ground and releasing its vapor from its leaves.
  19. Developed areas with little tree cover are “urban heat islands” that absorb and retain heat, making them 5-9 degrees F hotter than surrounding landscapes.
  20. Shade air conditioner condensers to increase efficiency. (Allow 3 foot clearance for proper air flow.)
  21. Mature trees do not have taproots. Most roots are within 18 inches of the surface, and extend far beyond the tree’s dripline.
  22. Pruning trees at planting, except to remove dead or diseased limbs, is not recommended. Pruning decreases the ability of the tree to generate new roots.
  23. Smaller trees transplant much more effectively than larger ones. For every inch of trunk width (caliper), it takes about one year for the tree to recover from transplant shock. An 8 foot tree and a 12 foot tree will probably reach the same height within 5 years.
  24. Some researchers believe that use of woodchips from diseased trees spreads pathogens, and endangers other trees.
  25. Many good things come from trees, such as coffee, chocolate, syrup and … imitation bacon.
  26. Backfilling new plantings with high-quality soil may be harmful. Some research shows that if backfilled soil is higher quality and different in texture than surrounding soil, it will inhibit root growth into the surrounding soil. The ultimate result may be girdling of roots.
  27. Avoid planting too many of the same species of tree. If one tree is attacked by insects or disease, there is the risk of similar damage to all trees of the same species.
  28. The Morton Arboretum recommends the following trees, among others:
    Southern exposure: Ohio Buckeye, Oaks, Kentucky Coffeetree, Freeman Maple, Shagbark Hickory, Northern Catalpa (all open-branched trees)
    Western exposure: Serviceberry, American Hornbeam, European Hornbeam, Winter King Hawthorn, Magnolias, Crabapples, Ruby Horsechestnut (all low-branched trees)
    Northern exposure: Evergreens, or low-branched deciduous trees planted densely.