Abstract
From the end of the 18th century, large areas of Central Europe were afforested with conifer monocultures following a long period of excessive forest use. Today, the conversion of these anthropogenous conifer forests into natural, mixed broad-leaved forests, serving manifold socio-economic and nature conservation purposes, is a major objective of sustainable forestry. The study presented here focuses on recent processes of natural regeneration on formerly degraded forest sites. Both the vegetation and land-use history and the present vegetation and vegetation dynamics are investigated. In the Menzer Heide (Brandenburg), selected as a representative area of the North-eastern German lowlands, anthropogenous Pinus sylvestris L. and natural Fagus sylvatica L. as well as mixed Quercus-Fagus forests of Qu. petraea Liebl. and Qu. robur L. are taken as examples. The methods applied are pollen and lake sediment analysis to reconstruct the historical vegetation and landscape development, phytosociology to differentiate the main forest communities, and population ecological and statistical methods to investigate vegetation dynamics and the spontaneous rejuvenation of trees within the forest stands. The sites investigated are oligotrophic and acid sandy soils far from ground water. The present-day forest communities reflect differences in soil nutrient supply, site history and forest management. Comparing a vegetation survey from the 1960s with a recent survey, soil regeneration processes can be revealed, indicating an increase of the nutrient availability in today's forests. The records of spontaneous tree rejuvenation show the major role played by beech and oak in the area investigated. From the results of the vegetation and land-use history analysis, the vegetation dynamics observed over the past decades, and the detailed analysis of the actual vegetation, scenarios for the future development towards natural forests are derived.