The impact of air pollution on terrestrial managed and natural vegetation.
There is a long history of awareness of air pollution impacts on vegetation but until the twentieth century this was largely based on field observations of injury to vegetation in the absence of measurements of the pollutants. In the UK following the industrial revolution urban air quality became very poor with phytotoxic SO2 and NO2 concentrations and remained that way until the mid-twentieth century. Since then both air quality and our understanding of pollutants have greatly improved.
Air pollutants remain a threat to natural and managed systems. Air pollution impacts for four major threats to vegetation are discussed through a series of case studies. Gas phase effects by the primary emissions of SO2 and NO2 are discussed in the context of impacts on lichens in urban areas, effects of wet and dry deposited acidity from sulphur and nitrogen compounds are considered with a particular focus on forest decline in Europe and the US, ecosystem eutrophication by nitrogen deposition with a focus on heathland decline in The Netherlands, and ground level ozone present at phytotoxic concentrations is discussed with a focus on impacts on semi-natural vegetation. We find that although progress is being made in all areas, there is much room for additional improvement especially for the effects of eutrophication globally on managed and natural ecosystems.