Possibilities and limits of integrating successional processes in the renaturation of non-natural pine forests influenced by late-flowering bird cherry (Prunus serotina EHRH.) with a view to minimizing the intensity of intervention
The conversion of large areas of pine forest into near-natural, structurally rich deciduous and mixed deciduous forests is an important objective of DBU-Naturerbe GmbH. In some areas, however, these efforts at renaturation are influenced by dense layers of vegetation (dominant stands) of late-flowering bird cherry. Its broad ecological amplitude and other species characteristics make it difficult to deal with this neophyte native to North America. The limited success of conventional control strategies (mechanical, chemical and biological) from an economic and ecological point of view increases the need for alternative approaches in dealing with this tree species.
The research project aims to increase the level of knowledge about the possibilities of using near-natural processes (succession, natural regeneration) in the conversion of weeping cherry-influenced pine stands. To this end, the regeneration options for sessile oak, hornbeam, small-leaved lime and copper beech under the problem stands are to be examined in order to subsequently derive practical approaches for human action. The scope of the planned regeneration ecology studies ranges from a greenhouse trial and various field trials to radiation measurements under dominant stands of late-flowering bird cherry.
A sowing trial under controlled conditions will be used to test the influence of weeping cherry litter and reduced radiation on the germination and development of the tree species in question. The necessary germination substrate will be acquired in the Oranienbaumer Heide study area. The experiment will be carried out over a four-month observation period in the greenhouse of the Hetzdorf/TU Dresden experimental and teaching facility. Three shading variants are used to simulate different densities of weeping cherry stands. Controlled irrigation is carried out during the trial period.
Another core element of the project is regeneration ecology trials in the field. These will be carried out on two natural heritage sites with existing dominant stands of late-flowering bird cherry (Authausener Wald and Rüthnicker Heide). The development of sessile oak, hornbeam, small-leaved lime and copper beech under problematic stands of different ages will be investigated over two growing seasons by means of planting trials. One-year-old container plants will be planted in the stands. In order to test the natural establishment potential of the semi-shade and shade tree species in the stands, sowing trials will also be carried out in the field.
In order to quantify the influence of the late flowering bird cherry on the availability of radiation on the forest floor, radiation measurements will be carried out. Hemispherical photos will be taken and analyzed in dominance stands of different ages.
The regeneration ecology studies of the planned project are intended to contribute to achieving forest dynamics that are as close to nature as possible in the renaturation of weeping cherry-influenced pine forests.