Kritische Konzentration von Blei und Cadmium fuer Jungwuchs der Buche Fagus sylvatica L. : Expertentagung Waldschadensforschung im oestlichen Mitteleuropa und in Bayern

1991

S. 446-450

28 Lit. Ang.

Unselbständiges Werk

200099170

Atmospherically transported heavy metals were repeatedly proved to accumulate in upper soil layers of forest ecosystems. Increasingly mobilized by acidification processes these metals may have toxic effects on trees. Based on several dose-response-experiments the toxicity of root-applied Pb and Cd for young plants of Fagus sylvatica L. was evaluated. Considering root elongation of seedlings as a rather sensitive parameter, plant available soil concentrations (NH4 - acetate - extractable fraction) of 24 ppm Pb and 2 ppm Cd must be regarded as "critical" concerning depression of root growth. Effects on growth and mineral nutrition of young beech trees studied during three vegetation periods in sand culture indicated that threshold concentrations in the long term aspect are even lower than 20 ppm Pb and 1 ppm Cd, especially when applied in combination. The data indicate that present-day concentrations of Pb in many acid forest soils of Central Europe are sufficiently high to affect germination and growth of saplings. Levels of Cd actually may not yet have adverse effects, but may be detrimental in the long run and in combination with other toxic elements. Thus, especially Pb must be taken into account as a contributing factor to forest dieback at acidified stands.