The objective is to investigate structure, dynamics and stability of Scots pine and beech forest ecosystems in the northeastern German lowlands. The presented results support the hypothesis that N-deposition in combination with low precipitation (550-620 mm annual rainfall) led to a measurable change of the vegetation of Scots pine stands in the research area since the end of the 1970's. In some cases, Scots pine ecosystems, with ground vegetation now dominated by tall grass species (Calamagrostis epigeios), have reached the stages of highest instability. Our ecological studies could reveal the basic mechanisms of these dynamics: Systems of differently opened element cycles could be realized, depending on precipitation and ecosystem structure. Three phases of growth behavior can be distinguished, depending on growth duration and intensity (nomal (1), accerlerated (2), and reduced (3) growth). The enormous water consumption of dense grass carpets can endanger Scots pine forests. For the quantification of water uptake by ground vegetation, adjustable mini-lysimeters were developed and installed. In order to regionalize the results of single-point investigations, a conceptual model using structural parameters was developed. A simulation module was implemented to model below-canopy precipitation in relation to structural parameters of the three layer. The project is continued with more precise and expanded objectives in order to compare between beech, oak, and pine ecosystems. (orig.)Available from TIB Hannover: F95B1167+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman
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