Reaction of mycorrhizal and non-mycorrhizal Scots pine fine roots along a deposition gradient of air pollutants in eastern Germany

Based on an ecosystematic approach within the comprehensive SANA (Regeneration of the atmosphere above the new federal states) -project the influence of industrial air pollutants (SO₂, NO_x, alkaline fly ashes) on the vitality of mycorrhizae, mycorrhizal frequency, and on parameters of root growth such as root biomass and necromass and distribution of different root classes in the soil horizons was investigated. The studies were conducted in three comparable Scots pine ecosystems in eastern Germany which were exposed to different deposition loads of air pollutants during the time of the former German Democratic Republic. Site specific differences were obtained for all parameters investigated. The reference plot Neuglobsow (background deposition) revealed the highest number of vital mycorrhizae, highest mycorrhizal frequency, and largest biomass of finest roots in the humus layer. At the impact-sites Roesa and Taura (heavy and moderate deposition) located near Halle/Bitterfeld and Leipzig, the number of vital mycorrhizae was reduced and the life-span of mycorrhizae of reduced vitality was elongated. Finest root biomass and necromass of the humus layer were also lower at these plots as compared to Neuglobsow. At Neuglobsow a higher turnover of mycorrhizae and finest roots of the humus layer is assumed. The reduced growth of mycorrhizal and non-mycorrhizal finest roots at the two pollution impacted sites Roesa and Taura is seen as an adaptation mechanism of the root system to high nutrient inputs.