Walddynamik auf Sandböden in der Lüneburger Heide (NW-Deutschland)
General patterns of forest dynamics on nutrient-poor, sandy Saalian deposits of the central Lüneburger Heide area (Lower Saxony, FR Germany) are described. Data about the tree species' natural history, observations on recent forest dynamics in protected stands, and palynological and historical records are used to construct a hypothetical scheme of successional processes in the "virgin forest" (approx. 800 A.D.) with low human influence and in the forests at present. Since only six tree species with contrasting natural history attributes occur in the forests on dry sandy soils in this area, rather deterministic models of forest dynamics can be applied. Silver Birch (Betula pendula) presumably was the dominating pioneer species in large gaps in the virgin forest but has been replaced by Scots Pine (Pinus sylvestris) in our times due to the wide distribution of planted seed-producing pine trees. Both pioneer species are unable to regenerate significantly in closed stands and, therefore, should have played only a minor role in later beech-dominated successional stages in the virgin forest. Soil chemical analyses and palynological records indicate that forests dominated by European Beech (Fagus sylvatica) must have been present as late successional stages on nutrient-rich as well as on nutrient-poor substrates in the Lüneburger Heide. No evidence was found for the natural occurrence of birch and oak-dominated forest communities on sites too poor for beech growth as was postulated by earlier botanists. Recent birch and oak (Quercus robur and Qu. petraea) stands mainly originate from coppicing or represent successional stages towards beech-dominated forest communities. However, high game densities and the fragmentation of forest cover may retard or even prevent the invasion of oak and beech individuals into pioneer communities. Norway Spruce (Picea abies) probably was absent from the virgin forest on dry sites but had some natural strongholds in isolated mires of the Lüneburger Heide. Its spontaneous occurrence in a greater number of forest communities in our times is seen as a consequence of the widespread presence of planted spruce forests in this area.