The value of trees in our urban landscape
The value of trees within an urban environment is widely accepted as high due to their positive contribution towards maintaining a city’s sustainability and to community health and serenity. Collectively, trees add beauty to our urban landscapes by softening the harsh lines of buildings, complimenting architecture, screening unsightly views and providing privacy and a sense of security and place.
Trees absorb air pollutants, release oxygen and sequester carbon dioxide. They reduce stormwater runoff and erosion, ameliorate climate, can save energy, provide wildlife habitat and strengthen a sense of community within a given area.
The benefits of trees can be grouped into social, environmental, and economic.
Trees and other landscape plantings provide the community with a fundamental reminder of nature as an important component of people’s lives. In an urban environment trees provide a critical link to the natural world from which we have evolved and help restore an individual's mind and spirit.
Humans respond to nature, we like trees around us because they make life more pleasant. The understanding of the role that trees play in our urban environment has lead to an increase in the veneration of trees and they can evoke strong passions, particularly when their removal is debated.
Trees alter the environment in which we live by moderating climate, improving air quality, conserving water and providing habitat for wildlife.
Trees modify local climate, primarily by lowering air temperature and increasing humidity. Trees shade buildings and hard surfaces reducing re-radiated energy and the ‘heat island’ effect. The evaporation of water from trees also has a cooling effect.
Wind speed and direction can be affected by trees. The more compact the foliage on the tree or group of trees, the greater the influence of the windbreak.
Trees can influence the flow of water in several ways. The downward fall of rain and hail is initially absorbed or deflected by trees, reducing the force. This allows greater capture of rainfall into the soil reducing runoff and erosion. Water is also allowed to percolate through the natural mulch layer created beneath the canopies of trees.
Trees remove carbon dioxide from the atmosphere and store (sequester) it as carbon in the plant material and the surrounding soil. Trees can have a significant impact through the effects they create when strategically planted near buildings, leading to a reduction in energy use.
Trees, and in particular native vegetation, benefit biodiversity (diversity of ecosystems, species and genes within species). Diversity of trees and shrubs in the urban landscape return it to a more natural, less artificial environment. Birds and other wildlife are attracted to the area as a result of trees.
Individual trees and shrubs have value, but the variability of species, size, condition and function makes determining their economic value difficult. The economic benefits of trees can be both direct and indirect.
Direct economic benefits are usually associated with energy costs. Well-placed shade trees can reduce energy consumption in a home by as much as 30 percent.
The indirect economic benefits of trees are based on the cumulative effect of individual savings and reliance on external energy sources.
Studies have shown that trees in the metropolitan area contribute between 13 and 20 percent of the value of the property. Houses located in tree-lined avenues have higher property values than those without street trees. Well treed suburbs are more appealing to newcomers.
Research has established a number of benefits in terms of consumer experiences of business districts with trees. Consumers generally reported a willingness to pay an average of 11% more for goods in a landscaped business district than a non-landscaped district, with this figure being as high as 50% for convenience goods.
Trees require an investment
While trees provide numerous benefits, they also incur some costs. The most significant costs incurred will include the initial tree purchase and establishment, while the disposal of leaves, branches and ultimately tree removal can be expensive.
The greatest benefit is derived from healthy, structurally sound trees planted in locations that support their development. Planting the right tree in the right place will maximise benefit while minimising the costs.
The long-term goal of urban tree management is sustainability; the maintenance of ecological, social and economic functions for the duration of a trees useful life.
Some information within this fact sheet has been obtained from a number of published sources. For further reading, refer to the Trees – Further Reading Fact Sheet.