Abstract
The creation and restoration of natural woodland serving diverse socio-economic as well as nature conservation purposes has become a major objective of sustainable forestry throughout Europe. There is a main focus on the conversion of anthropogenous coniferous forests, which are widely spread in the Central European lowlands and mountain ranges, into natural broad-leaved forests. For ecological as well as economic reasons, the integration of natural regeneration processes into conversion management is considered an important task. Taking the woodland of the Menzer Heide (NE Germany), a typical Pleistocene landscape in the northern Central European lowlands as an example, a vegetation analysis of the Scots pine (Pinus sylvestris L.) plantations dominating in this area is presented. As the main results, (1) two communities are differentiated within the present-day pine plantations on the oligotrophic and acidic sandy soils. Indicated by different species compositions, the Dicranum-community and the Oxalis-community occur, the latter growing on sites with higher nutrient availability. (2) The comparison of an historical with the present vegetation analysis reveals an increase of nutrient availability in recent decades, most probably strongly related to the natural soil regeneration of the formerly exploited forest sites. (3) From the results of the vegetation analysis, including records of species and individual numbers of naturally rejuvenated trees, future stand development scenarios can be derived. Thus, the Oxalis-community may directly develop into oak-beech and beech stands as natural forests. In the long term, the Dicranum-community will pass a regeneration stage with pine and oak, probably further developing towards natural oak-beech and beech forests. In conclusion, decisions regarding extensive or intensive management, aiming at the conversion of coniferous plantations into natural broad-leaved forests, can be made following observation of the natural regeneration processes in the present-day stands. By utilising the natural regeneration processes and by applying only a few controlling silvicultural measures, a low-energy and cost-effective conversion of the forests can be accomplished.