Gibt es eine Nahrstoffmangel-Grenze der Buche im nordwestdeutschen Flachland?

Abstract

Comparative soil chemical analyses were conducted in four forest stands dominated by European beech (Fagus sylvatica) and four birchoak, birch-pine or oak-birch-pine stands on nutrient-poor sandy Saalian glacial deposits in the Lüneburger Heide area of NW Germany. In addition, soil chemical data of R astin & U lrich (1988) from eight further stands were used. Up to now, birch-oak forests are believed to represent the natural vegetation on very poor soils that should not support beech growth. Our results, however, show that beech forests occur not only on richer substrates but even on melt water sands with very small pools of salt-extractable cations (Ca, K, Mg), a low nitrogen mineralisation rate and a high soil acidity (pH (KCl) < 3.0) in the uppermost profile. Nutrient availability of the mineral soils did not differ significantly between poor beech communities and birch, pine or oak-dominated stands. The pool size of plant-available nutrients in these poor glacial deposits was mainly determined by the depth of the organic layer profile and its nutrient stocks, while properties of the mineral soil profile (such as origin of parent material or degree of podsolisation) were less important. Thus, it is believed that parent material with only small pools of plant-available nutrients does not restrict the occurrence of beech on poor sandy soils in the diluviallowlands of NW Germany. If deep organic layers are present on these substrates, sufficient nutrients for beech growth seem to be supplied despite a poor mineral soil. It is concluded that before man started to extensively destroy the forests in the Middle Ages beech must have been more widespread in this region, not only on rich but also on poor sandy soils, than believed until now.