ABSTRACT

In this chapter we discuss how urban trees can contribute to mitigation of pollutants in highly urbanised areas. Reducing pollutant emissions is the main change required to improve environmental quality in urban areas, but hard surfaces and all activities in urban settings, especially transport, contribute to generation of pollutants, and will continue to do so in the future low-emitting cities. Mitigation using urban forestry could address part of the problem, with one of the most important ecosystem functions of vegetation in densely populated areas and along roads being to help protect people from pollution. Special attention must be paid to urban green elements, and dedicated designs are needed for mitigation of contaminants, which are most often of a diffuse nature in urban areas. However, the variation in pollution level between sites within cities can be larger than between so-called polluted and clean cities and thus the local situation should be the main focus when considering amelioration measures.