The Benefits of Trees in Towns and City

The aesthetic appeal of trees in the urban environment hardly needs to be stressed:  they enhance the beauty of cities, softening the harsh lines of urban infrastructure, adding colour, texture, and diversity to streetscapes. Certain trees (such as the King's Acre Lime) have an historical and cultural significance that can help maintain a connection to local heritage. However besides these there are a host of other benefits that urban trees provide, some of which are outlined below.

Environmental Benefits

• Air Quality Improvement: Urban trees absorb pollutants like nitrogen dioxide (NO₂), sulphur dioxide (SO₂), and particulate matter (PM). They also produce oxygen, helping improve air quality in cities where pollution can be a significant concern.

• Carbon Sequestration: Trees capture and store carbon dioxide (CO₂), helping to mitigate the effects of climate change. Although urban trees cover less area than forests, their role in carbon storage is crucial, especially in densely populated regions.

• Cooling Effect (Urban Heat Island Mitigation): Trees provide shade and release water vapor through transpiration, cooling down city temperatures. This can be particularly important during heatwaves, reducing the “urban heat island” effect that causes cities to be warmer than surrounding rural areas.

• Stormwater Management: Trees reduce surface runoff by intercepting rainfall with their leaves, branches, and roots. This helps to prevent flooding, particularly in cities where paved surfaces dominate.

• Biodiversity Support: Urban trees provide habitats for a wide range of wildlife, from birds and insects to small mammals, fostering biodiversity even in the heart of cities.

• Support for Wildlife:

  Trees are an important wildlife habitat. They provide nesting sites for birds and support a wide range of insects that are an important food source for wildlife. Trees that produce berries are a direct source of food for many bird species.
  In view of the historic decline in the UK's biodiversity, urban trees play a critical role in supporting declining species of birds, bats, and insects, especially in densely built-up areas. Trees and other vegetation along highways, waterways and railways are particularly important as linear 'habitat corridors': by connecting otherwise isolated areas and allowing wildlife to move more freely they are a significant factor in improving wildlife resilience

Reducing Energy Use

• Trees lower temperatures by shading buildings and pavement, which reduces the need for air conditioning. Shaded buildings can save up to 30% on cooling costs during summer months. Even a small tree in a UK city can offer up to 7 kW of cooling during the hottest months, surpassing the cooling power of most residential air conditioning units, which typically range between 1 and 10 kW.
• Heat Stress: Evapotranspiration of water from the leaves has a cooling effect on the surrounding air: by reducing heat stress in urban areas, trees also help prevent heat-related illnesses, which are becoming a growing concern in the UK as summers become hotter.
• Reduction in fuel costs:  Research in the USA has shown that careful tree planting can help to reduce the amount of fuel used both to heat and to cool buildings:  a 10% increase in the number of trees strategically placed around buildings can produce savings of 5–10% in heating and air conditioning costs.

Social and Health Benefits

• Mental Health and Wellbeing: Proximity to green spaces, including urban trees, has been linked to reduced stress, anxiety, and depression. Trees in parks and along streets offer aesthetic value, creating more tranquil and appealing environments.
• Physical Health: People who live near or have access to green spaces are more likely to engage in physical activities like walking, jogging, and cycling. This can help reduce obesity and related health issues.
• Reduction of Noise Pollution: Trees can act as natural sound barriers, absorbing urban noise and creating quieter spaces, especially in residential areas or near busy roads.
• Improved Social Cohesion: Well-maintained green spaces and tree-lined streets encourage social interaction, community engagement, and provide a pleasant environment for outdoor activities.
• Improved road safety: Contrary to received wisdom, there is in fact no correlation between the presence and density of roadside trees and the number of traffic accident fatalities. On the contrary, research has shown that the presence of trees, by improving drivers’ speed perception and reinforcing ‘edge awareness’, actually results in lower traffic speed and more cautious driving.
• Crime Reduction: 

  Traditionally, it has been thought that trees and other vegetation have a negative impact on crime because they provide cover for criminals and reduce opportunities for casual surveillance.

  However, research in the USA and elsewhere has showed that the reverse is true. One study found that for every 10 percent increase in tree canopy cover, there was a 15 percent decrease in the violent crime, and a 14 percent fall in the property crime rate.  There is also evidence that vegetation reduces mental fatigue, which is often a precursor of outbursts of anger and violence.

Economic Benefits

• Increased Property Values: Studies show that properties near trees or parks often have higher values than those in less green areas. Tree-lined streets and nearby green spaces make neighbourhoods more attractive, driving up demand and property prices.

• Energy Savings: By providing shade and reducing the need for air conditioning in summer, trees help lower energy consumption. Their windbreak effect in winter can also reduce heating costs by cutting down on cold winds.

• Attraction of Tourism and Business: Green, tree-filled areas tend to attract more visitors and businesses. Parks and tree-lined streets improve the aesthetic appeal of cities, drawing more tourists and creating vibrant shopping or leisure areas.

• Increased retail profitability: Research has shown that consumer behaviour can be affected by the presence of trees with visitors being found to be prepared to pay more for parking in landscaped car parks; they would also pay on average 11% and up to 50% more for goods being sold in a landscaped business district as compared to a non-landscaped district. This might, of course, encourage the thrifty to seek out treeless shopping centres! However, by rights it should positively encourage retailers to promote tree planting.

• Reduced Road Repair costs: Trees can have negative effects on the surface of footways and carriageways through direct root damage. However, the shade cast by trees can significantly increase the life of the road by reducing the temperature that the surface reaches during hot weather.

Climate Resilience

• Flood Risk Reduction: In urban environments, the extensive paving leads to rapid water runoff during heavy rains, contributing to floods. Urban trees help absorb and slow down water flow, reducing flood risks in low-lying city areas.
• Resilience to Climate Change: With climate change increasing the likelihood of extreme weather events, such as heatwaves and intense rainfall, urban trees can enhance cities' resilience by moderating temperature extremes and helping manage excess rainwater.