Human Health and Community Benefits of Landscape Trees.
Photo Courtesy of Ten Eyck Landscape Architects
“The Tree of Life” has been used by poets, philosophers, writers and artist of all stripes, to metaphorically present the idea of life and death since the time of the earliest human hunter-gather cultures. Trees were likely cultivated around the same time humans began growing crops and started living in permanent communities. We all embrace the calm and serenity a walk in a beautiful garden provides and how our surroundings can contribute to feelings of wellbeing.
Scientific evidence on the physical environmental benefits of landscape trees continues to expand. Overwhelming evidence supports the conclusion that trees mitigate the urban heat island, reduce particulate pollution, stabilize soil and reduce runoff and, when properly placed, reduce energy consumption for residential and commercial buildings. The direct benefits to human health are more difficult to measure scientifically but are, none the less, compelling and worthy of consideration. Here are a couple of examples from the scientific literature.
Recent studies in the health field have shown that being in nature reduces the biological markers of stress, relieved symptoms of depression and increases white blood cell counts.
Walking in forests reduces heart rate and cortical levels.
Women with more trees around their homes were less likely to have underweight babies.
Increased deaths from cardiovascular and respiratory diseases were highly correlated to the spread of insect infestation that was fatal to Ash trees in the mid west.
For a planting cost of $250-600 (includes first 3 years of maintenance) a single street tree returns over $90,000 of direct benefits (not including aesthetic, social and natural) in the lifetime of the trees.
A growing body of evidence suggests that the inclusion of trees and other streetscape features in the roadside environment reduces crashes and injuries on urban roadways.
By forming and framing visual walls and providing distinct edges to sidewalks so motorists better distinguish between their environment and one shared with pedestrians. Urban areas medians with trees are safer for drivers and pedestrians than those without trees.
Trees absorb the first 30% of most precipitation through their leaf system, allowing evaporation back into the atmosphere, storm water runoff and flooding potential to urban properties is therefore reduced.
Trees in close proximity to streets absorb 9 times more pollutants than more distant trees.
Trees have a calming and healing effect of ADHA adults and teens, reduces road rage on tree lined streets and reduce perceives travel time for commuters.
Trees planted along streets and along on-street parking, drivers slow their speed by 7 to 8 mph when compared to tree-less streets.
Contact with nature — with plants, with animals, with pleasing landscapes, and with wilderness — offers a range of medical benefits including lower blood pressure and cholesterol levels, enhanced survival after a heart attack, more rapid recovery from surgery, fewer minor medical complaints, and lower self-reported stress.
Research suggests that exercise is more beneficial — leading to enhanced tranquility and more relief of anxiety and depression — when it occurs in natural settings, like parks. The opportunity for so-called "green exercise" is an important asset that city parks offer.
Studies monitoring longevity of more than 3,000 people born between 1903 and 1918 and living in Tokyo, one of the most densely populated cities in the world showed that proximity to public parks and tree-lined streets appeared to have the greatest impact on the length of pensioners' lives, even when taking into account factors known to affect longevity, such as gender, marital status, income, and age.
Want to read more?
Exploring the connection between Trees and Human Health
Urban Street Trees: 22 Benefits Specific Applications
