The Bugwood Network

Trees and people

  • Trees supply oxygen in the air we need to breathe and keep our air supply fresh by absorbing carbon dioxide.
  • Trees lower air temperatures by evaporating water from their leaves.
  • Trees cut down on noise pollution by acting as sound barriers.  A 1970 study found a 6 to 8 decibel reduction in noise per 100 feet of forest cover.
  • Trees provide shade and shelter, reducing yearly heating and cooling costs in the U.S. by $2.1 billion.
  • Tree roots stabilize the soil and prevent soil erosion.
  • Ornamental trees may need pruning, fertilizing, and watering in order to thrive.
  • A tree doesn't reach its most productive stage of carbon storage until about ten years of age, and many urban trees don't survive that long.  The average tree in metropolitan areas survives only about 8 years!
  • An acre of trees is expected to grow 4,000 pounds of wood per year, consuming 5,800 pounds of carbon dioxide and releasing 4,280 pounds of oxygen.  Old, slow growing forests can consume more oxygen than they produce but young, vigorous forests tend to be the most efficient at absorbing carbon dioxide and producing oxygen.
  • One million acres of forest are lost to city growth in the U.S. each year.
  • Of every four city trees that die or are removed, only one is replaced.
  • In one year, a single average sized tree can absorb as much carbon from the atmosphere as is produced by a car driven 26,000 miles.
  • To store the carbon a person is responsible for producing in a lifetime, 45 seedling trees should be planted.
  • When a tree dies, it releases its stored carbon back into the air.  The death and rotting of one 70-year-old tree would return over 3 tons of carbon to the atmosphere.
  • U.S. forests remove about 9% of the nation's total carbon dioxide emissions.
  • Since 1990, the forest industry spends approximately $1 billion a year  about one of every five dollars earned  on environmental improvements and has committed itself to a major longterm research initiative with the U.S. Department of Energy to ensure continued productivity and environmental improvements into the next century.
  • Approximately 800 million tons of carbon are currently stored in U.S. urban forests, with an annual increase of 6.5 million tons.  With the next-best alternative control cost of $25 per ton, the carbon-storing capacity of U.S. urban forests exceeds $22 billion.
  • Trees reduce smog by absorbing smog-forming pollutants, such as ozone (O3), and lowering ambient temperatures.
  • A 1984 study of shade tree benefits showed lowered building temperatures in tree shade meant a comparative decrease in summer building energy use of up to 22% per square foot of air conditioned floor space.
  • A 1988 tree shade study of homes in Tucson and Miami showed that reductions in annual cooling energy use from dense tree shade were directly estimated to save $249 and $235 per home, respectively, with west wall shade providing the greatest savings.
  • A 1985 shade tree study found that street trees located on the south side of conventional homes could annually save $60 in Palm Springs in cooling costs and $16 in Sacramento, compared to homes with no trees.
  • A 1989 study showed tree shading of air conditioner units can increase air conditioner efficiency up to 10%.
  • A 1985 study in Pennsylvania found conifer windbreaks reduced winter wind speed by 50% and saved 6.6% of heating energy for mobile homes.
  • Hardwood tree canopies intercept and evaporate 7% of winter precipitation and conifers about 18 to 25%.  Together, hardwood and conifer canopies intercept 15 to 20% of growing season rainfall.
  • Soil erosion of forested lands averages about 50 tons per square mile per year.  Areas under development can reach soil erosion losses of 25,000 to 50,000 tons per square mile per year, or 500 to 1,000 years worth of "normal" forest land erosion per year.
  • A 1980 study of home value in a Connecticut town showed that 6% of total property value, or $2,686 per home, was due to tree cover.
  • A 1987 study of home value in Athens, Georgia found the average house sold for 3.5 to 4.5% more for having 5 trees in the front yard, with pines adding about $275 each, hardwoods $333 each, and large trees $336 each.
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The University of Georgia - Warnell School of Forestry and Natural Resources and
College of Agricultural and Environmental Sciences - Dept. of Entomology
Last updated on Thursday, March 20, 2003 at 10:15 AM
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