Two modeling approaches were applied to evaluate the potential risks of increasing atmospheric carbon dioxide concentrations and possible climate change on the vegetation cover of the Alpine region. The first model is a stochastic forest succession simulator, the second is a static regression type model. The questions of the study were as follows: (1) Which temporal vegetation changes might occur under given carbon dioxide and climate scenarios? (2) Which region of the Alps might be most susceptible to a vegetation change?

Tropospheric ozone is the most important single air pollutant of importance to forests in eastern United States. Both broadleaf and needled trees may suffer premature foliar senescence following even low ozone exposure years. Genetic sensitivity within species is likewise prevalent.

The area of productive woodland in the UK has been increasing steadily since 1950, generally at about 20-30 thousand hectares per year. The current forest estate covers 2,1 million hectares, the annual growth in the total stored carbon in wood is 2,0 million tonnes. The annual UK output of carbon dioxide from the burning of fossil fuels is 162 million tonnes.

Air pollutants cause subtle changes in natural resistance that can prediscope plants to insect attack. The majority of reports in the area of plant-pollutant-insect interactions have been correlative in nature. In the last ten years, there has emerged a growing body of literature, the vast majority with herbaceous crops, reporting on cause-effect relationships among insects and their hosts.

Visible chlorotic injury and reduced foliar biomass are found in Pinus ponderosa and P. jefreyi in the mountains of southern California and the west slope of Sierra Nevada. Reduced tree growth and accelerated rates of forest succession has been documented in this area, with ozone resistant, shade tolerant species replacing P. ponderosa. There may also be some interactions among ozone, drought stress, insects and fungal pathogens.

Long-term changes in forest soils are characterised by decreases in soil pH, exchangeable base cations, percent base saturation and accumulation of heavy metals. Acidic deposition effects on forest soils can be demonstrated experientially either in the laboratory or in the field by stimulated acid treatments.

Since the beginning of the 80's, a wide-spread damage to Norway spruce has occurred, mainly characterized by the light-induced decay of chlorophyll in magnesium-deficient needles. Damage also occurs in deciduous trees, especially in beech. To clarify the causes of the damage in Northrine-Wesphalian forests, extensive investigations have been carried out, which combined experimental techniques and epidemiologically orientated surveys.

Climate change effects on forest soils will occur directly on soils or indirectly through effects on tree growth. Increases in soil temperature will cause an increase in soil respiration and decomposition and many increase rates of mineral weathering and ion exchange reactions. Forest soils represent a major sink for C and increased productivity in response to elevated atmospheric carbon dioxide will lead to an increase in c storage in forest ecosystems. Changes in forest productivity will have significant effects on forest soils, included water use, soil moisture status and nutrient cycling.

Experimental research on the physiology of tree seedlings under simulated climate and doubled carbon dioxide can rarely be extrapolated to grown forests. Climatological research has demonstrated a warming trend in the north and a cooling trend in the south of China. However, the changing climate has not caused the death of forests. Projecting the impact of climate change on forest distribution and growth using current GCMs seems to be the only method available.

Most concern about the effects air pollution has been directed towards central and northern Europe, although considerable damage has been attributed to air pollution in the Mediterranean countries. The damage is mostly in the vicinity of point sources and can usually be related to specific pollutants such as sulphur dioxide and hydrogen fluoride.