Pollution Control
With growing concern about pollution and climate change, trees are an excellent producer of Oxygen and act to lock away Carbon during their growth cycle. The main way that a tree combats pollution is through acting as a sink or receptor and catching suspended particulate matter (s.p.m.) on it's leaf surface. This helps remove a number of pollutants including Nitrogen Oxides, Sulphur, Ammonia and Dust Particles. At the end of the growing season the leaves are then discarded by the tree.
Research suggests that, taking into account variables such as climate, species, location, etc., it is difficult to formulate standards that quantify rates of pollution absorption. Although the most effective way to combat pollution is at source, it is the case that trees do have a positive effect on the environment and do reduce levels of pollutants.
Studies have shown that trees exert an influence on the micro-climate
of the surrounding area contributing to cleaner air and a healthier
environment. They do this in two principal ways, firstly by capturing
particulate matter ie. air-borne pollutants and secondly by cooling and
humidifying the surrounding air, thus reducing the energy required to run
air/con systems. Trees have also been shown to reduce wind speeds with positive
effects on heat loss from buildings as well as acting as a buffer against high
noise levels.
Aesthetic Benefits
Whilst it is true that trees act to mitigate the effects of pollution
one of the primary reasons for planting trees in the city remain
aesthetic, otherwise ugly areas can be transformed by the introduction
of several species of tree. Trees provide a general softening of the urban environment
and also provide a counterbalance for the larger elements of the built environment. The
aesthetic of tree lined streets and green spaces have been shown to have
positive psychological benefits including lower rates of mental illness,
violence and crime.
Trees have tremendous symbolic value, they humanise the city, acknowledge our affinity for the natural world and provide a focus for community participation in landscaping the urban environment.
Tree Economics
Trees add value. First of all they can act as 'green magnets' attracting businesses and their employees into an area. Secondly they can literally add up to 15% to the values of property in a tree lined street.