Das Projekt "Early successional changes in forest ecosystems after a gap-forming disturbance" wird vom Umweltbundesamt gefördert und von Technische Universität München, Fachgebiet Geobotanik durchgeführt. The Project is aimed at studying the early successional changes in a forest gap which forms as a result of a natural or man-made disturbance, like windfall or clear cut. Those changes will be considered in terms of the herbs-tree (or shrubs-tree) competition dynamics of dominant species. The problem is complicated since the competition mechanism results in different outcomes at different stages of ontogenesis: the megaforbes (shrubs) suppress tree seedlings, whereas adult trees shade the herbage. Any formal description of the competition dynamics has therefore to consider the population age structure and ontogenetic stages of the individuals. The goal of the Project will thus be achieved by means of a new methodology which shall combine: - field studies of the population biology of the clonal plant species along the gradient of increasing strength of the competition; - the unique experience in quantifying the current status of a population in terms of its age structure and ontogenetic stages of the individuals, and; - an original approach to modelling the age-stage-structured population dynamics by means of matrix population models. This methodology will be applied in the three case studies designed within similar areas in Germany, Switzerland, and Russia, with the clonal plant species of similar biology, such as Calamagrostis spp. and Rubus idaeus, and the tree species like Betula pendula. These three case studies will be combined in the forth one devoted to construction, calibration and verification of the corresponding, case-specific models of age-stage-structured population dynamics. The models are expected to reproduce the observed competition effects as different patterns in their dynamic behaviour. They will have to simulate the course and outcome of the competition dynamics under alternative, case-specific scenarios of forest management at the early stage of tree regeneration. Practical recommendations can be formulated from the results of those model experiments. The proposed research is innovative as it will extend the knowledge of competition dynamics of vegetation in forest gaps, and it will also contribute to filling-in the existing gap in the theory and modelling methods for population dynamics of species with explicit age-ontogenetic structure.