Das Projekt "Langsfristige Dynamik von Eichen-Oekosystemen: Erforschung der Rolle von Wurzelpathogenen und Umweltbelastungen als interagierende verschlechterungsausloesende Faktoren" wird vom Umweltbundesamt gefördert und von Technische Universität München, Lehrstuhl für Forstbotanik, Arbeitsgruppe Phytopathologie durchgeführt. The general objective is to improve our understanding of the complex processes governing long term dynamics of oak ecosystems, that may sometimes derive in severe and recurrent decline episodes. We will concentrate on the role of root pathogens in interaction with environmental constraints as potential decline inducing factors. As a result of this effect, comprehensive conclusions will contribute to improved oak forest management that enable to escape or to contain decline hazards. The research proposed will interact between two groups of disciplines, ecophysiology and pathology. Two groups of pathogens will be considered, those infecting fine roots (Pythiacious fungi: Phytophthora and Pythium species) and those infecting big roots (root and butt rot basidiomycetes like Armillaria spp and Collybia fusipes). The project aims at clarify the possible impact of Pythiacious fungi, particularly Phytophthora species on oak. This will be obtained in an extensive survey of oak ecosystems for establishing the distribution of fungi in soils, then investigating the pathogenicity of isolated strains. Moreover, a special attention will be paid to water status of oaks in presence of root pathogens; and nitrogen nutrition will be also considered. Water status of trees will be investigated as a predisposing factor, as well as a consequence of root infection.