Comparative evaluation of the effects of gaseous pollutants, acidic deposition, and mineral deficiencies on the carbohydrate metabolism of trees

With a focus on conifers, recent literature on the interaction of pollution, acidic deposition and mineral (mainly Mg) deficiency on plant carbohydrate metabolism is reviewed. By combining most recent knowledge about the regulation of carbon partitioning and allocation of photoassimilate with data on symptom-related pool sizes of carbohydrates, biochemical indications for shifts in allocation are presented. In summary, the data, although in part conflicting, indicate that the impact of pollutants at moderate levels (up to three times ambient concentration) should not be responsible for the decline symptoms observed.