All About Trees

Photo Credit: DN Davis

Trees are critical to all aspects of life—our health, our economy, and our environment. Just take a look at the following facts to see for yourself.


  • A healthy 100-foot-tall tree has about 200,000 leaves. A tree this size can take 11,000 gallons of water from the soil and release it into the air again as oxygen and water vapor in a single growing season.

  • Native tree species support natural ecosystems by providing habitat and food for birds, mammals, and insects.

  • The planting of trees improves water quality. Tree’s complex root network reduces runoff and erosion. This allows more recharging of the ground water supply. Wooded areas help prevent the transport of sediment and chemicals into streams.

  • In addition to all these things, forested streamside buffers also filter sediment from streams, stabilize streambanks, shade and modify stream temperatures, sequester carbon to help mitigate greenhouse gas emissions, and reduce downstream flooding. And the presence of mature trees in a buffer makes the stream wider.

Pollution Reduction

  • A mature tree absorbs carbon dioxide at a rate of 48 pounds per year. In one year, an acre of forest can absorb twice the CO2 produced by the average car's annual mileage.

  • Studies show up to 88 percent of nitrate and 76 percent of phosphorus is reduced after agricultural runoff passes through a forested streamside buffer.

Urban Benefits

  • A single street tree returns over $90,000 of direct benefits (not including aesthetic, social, and natural) in the lifetime of the tree, for a planting cost of only $250-600 (includes first three years of maintenance) .

  • Trees contribute to longer pavement life due to reduced heating/cooling (expansion/contraction) of asphalt.

Economic Development

  • In one study, 83 percent of realtors believe that mature trees have a "strong or moderate impact" on the salability of homes listed for under $150,000; on homes over $250,000, this perception increases to 98 percent.

  • A number of studies have shown that real estate agents and home buyers assign between 10 and 23 percent of the value of a residence to the trees on the property.

  • Trees can be a stimulus to economic development, attracting new business and tourism. Commercial retail areas are more attractive to shoppers, apartments rent more quickly, tenants stay longer, and space in a wooded setting is more valuable to sell or rent.

  • A U.S. Forest Service study found that a 10 percent increase in tree canopy was associated with a roughly 12 percent decrease in crime.

Health

  • Surgery patients who could see a grove of deciduous trees recuperated faster and required less pain-killing medicine than matched patients who viewed only brick walls.

  • In one study, stands of trees reduced particulates by 9 to 13 percent, and the amount of dust reaching the ground was 27 to 42 percent less under a stand of trees than in an open area.

  • Trees filter airborne pollutants and can reduce the conditions that cause asthma. Asthma incidents increase in urban communities where trees are eliminated in favor of new roads, homes, or commercial developments.

Energy

  • Trees properly placed around buildings can reduce air conditioning needs by 30 percent and can save 20-50 percent in energy used for heating.

  • The net cooling effect of a young, healthy tree is equivalent to 10 room-size air conditioners operating 20 hours a day.

  • Trees reduce annual heating and cooling costs for a typical residence by 8 to 12 percent and increase property values by 10 to 15 percent.

Flooding

  • Forests filter and regulate the flow of water, in large part due to their leafy canopy that intercepts rainfall.

  • Average interception of rainfall by a forest canopy ranges from 10 to 40 percent depending on species, time of year, and precipitation rates per storm event.

  • A mature evergreen can intercept more than 4,000 gallons of rainwater per year.

  • In urban and suburban settings, a single deciduous tree can intercept from 500 to 760 gallons of rainwater per year.

Learn more about trees on our Resources page.