Benefits of Trees in the Urban Environment
Trees are all around us in the countryside but we are normally not far from a tree even when we are in a city. The benefits of trees are often ignored or simply not understood. Here are some of the many benefits that trees provide society.
Trees provide shade
Trees provide shade for us all. Yes, ok, we live in wet and cold Britain but the shade provided by trees helps to keep you and your car cool throughout the year. They also keep your house cool in the summer and warmer in the winter by trapping the heat under the canopy. On hot days the shade of a tree can be a welcome relief in the city which can be 5 degrees warmer than the neighbouring countryside. It is called the urban heat island effect but trees help more than just providing shade…
Trees cool the air
When light falls onto a black or dark surface, such as the roofs and tarmac roads in cities, the energy is absorbed and the surface is heated. This causes the surrounding air to be heated and we end up with hotter air in the city. This heating effect is the main cause of the urban heat island effect
When trees absorb light and use the energy in photosynthesis to produce oxygen and, as the energy is used, it does not turn to heat. Trees therefore intercept light which would otherwise fall on asphalt causing temperatures to rise. But it gets better, trees can actually cool the air.
Trees take water from the air and use it for photosynthesis (the hydrogen from water combines with the carbon dioxide, CO2, to form carbohydrates in the form of glucose, which the tree uses/stores for energy. As the water molecule, H2O, looses its hydrogen atoms it becomes a free oxygen molecule, O2) but trees take more water from the ground than they need, this water is lost through the leaves and evaporates. As the water evaporates and passes through the air it cools the air in a process known as evaporative cooling.
They absorb pollution
Some species of tress are chosen as street trees because they are very tolerant to the pollution in city air. They are also able to remove CO2, pollution and other particles from the air. They also produce oxygen giving us cleaner, more oxygenated air in the city making the air healthier for us all.
Carbon capture – carbon sink
As mentioned above, as the tree photosynthesises it captures carbon dioxide from the air and converts this into carbohydrates. This carbon is then used by the tree to grow and live. Although some of the carbon is released back into the air much of the carbon is ‘locked’ into the tree’s timber, branches and roots. Again this removes carbon directly from the air making the city air cleaner.
They provide a screen
Trees can be used to screen unsightly views but they can also be used to reduce noise and pollution, particularly evergreen species. The can also provide shelter from wind and rain and prying eyes.
Help to prevent flash floods
Trees slow rain as it falls through the air, the rain is held on leaves slowing its progress to the ground. This allows soil more time to absorb the water. More importantly for the urban environment trees slow the water from running down the road and down the drain. This reduces the surge of water entering our sewers and can prevent flash floods. On steeper ground the tree roots tie the ground together to prevent landslides and stops river banks from washing away.
Trees provide homes and food for many animals from birds and squirrels to insects and bats. Trees also provide wildlife corridors allowing animals to move from one green area to another.
Trees make people happy and give a can reduce stress. They can soften the harsh urban environment and provide a connection to natural habitat. Many people enjoy walking in our forests and parks, spending time amongst trees. This was particularly evident in early 2011 when over half a million people signed a petition to prevent the sell off of Forestry Commission woodland.
Increased property prices
As a result of all these benefits properties areas with a high number of trees can have a value upto 20% higher than equivalent properties in areas with fewer trees.
If you know of anymore benefits of trees please let us know by using the comment section below
References and further reading
- Benefit of Trees – ISA
- Benefit of Trees – Arborday Foundation
- 38 Degrees – Government To Scrap Plans To Sell Our Forests
- Trees in Towns II
- Assessing the Value of Trees and Shrubs – BHG