Forest ecosystems represent a major type ofland use in Germanyand in Europe. They provide a number of functions, or ecosystem services, beneficial to humans, namely biomass production, regulation of the water- and energy cyde, C and N sequestration, erosion control, recreation, and they act as habitat for numerous species. The stability of forest ecosystems in Europe as influenced by the deposition of air pollutants has been a matter of debate for more than 20 years. Besides atmospheric deposition, other environmental conditions affecting forest ecosystems, such as temperature, CO content of the atmosphere 2 and precipitation, have significantly changed in the past and continue to change in the future. Quantifying and predicting the effects of these changes on ecosys­ tem functioning are achallenge to ecosystem research and also a requirement to establish sustainable use of forest ecosystems in the future. This book summarizes results of long-term, interdisciplinary ecosystem research conducted in two forested catchments and coordinated at the Bayreuth Institute of Terrestrial Ecosystem Research (BITÖK), University of Bayreuth, Germany. It does not aim to summarize all the research of BITÖ K in the past decade, which would go far beyond the studies in these two catch­ ments. Instead, we concentrate here on the long-term developments in the biogeochemistry of carbon and mineral elements and on the water cyde, at both the plot and the catchment scale.

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Part I Introduction 1 Biogeochemistry of forested catchments in a changing environment: Introduction Egbert Matzner 2 The Lehstenbach and Steinkreuz catchments in NE Bavaria, Germany Pedro Gerstberger, Thomas Foken, Karsten Kalbitz Part II The changing environment 3 Trace gases and particles in the atmospheric boundary layer at the Waldstein site: Present state and historic trends Otto Klemm 4 Climate change in the Lehstenbach region Thomas Foken Part III Vegetation response 5 Atmospheric and structural controls on carbon and water relations in mixed-forest stands of beech and oak Barbara Köstner, Markus Schmidt, Eva Falge, Stefan Fleck, John D. Tenhunen 6 Impacts of canopy internal gradients on carbon and water exchange of beech and oak trees Stefan Fleck, Markus Schmidt, Barbara Köstner, Wolfgang Faltin, John D. Tenhunen 7 Soil CO2 fluxes in spruce forests - Temporal and spatial variation, and environmental controls Jens-Arne Subke, Nina Buchmann, John D. Tenhunen 8 Carbon budget of a spruce forest ecosystem Corinna Rebmann, Peter Anthoni, Eva Falge, Mathias Göckede, Alexander Mangold, Jens-Arne Subke, Christoph Thomas, Bodo Wichura, Ernst-Detlef Schulze, John Tenhunen, Thomas Foken 9 Structure of carbon dioxide exchange processes above a spruce forest Bodo Wichura, Johannes Ruppert, Antony C. Delany, Nina Buchmann, Thomas Foken 10 Modeling the vegetation atmospheric exchange with a transilient model Martina Berger, Ralph Dlugi, Thomas Foken 11 Fog deposition and its role in biogeochemical cycles of nutrients and pollutants Thomas Wrzesinsky, Clemens Scheer, Otto Klemm 12 Turbulent deposition of ozone to a mountainous forest ecosystem OttoKlemm, Alexander Mangold, Andreas Held 13 The emissions of biogenic volatile organic compounds (BVOC) and their relevance to atmospheric particle dynamics Rainer Steinbrecher, Bernhard Rappenglück, Armin Hansel, Martin Graus, Otto Klemm, Andreas Held, Alfred Wiedensohler, Andreas Nowak 14 Trends in deposition and canopy leaching of mineral elements as indicated by bulk deposition and throughfall measurements Egbert Matzner, Tobias Zuber, Christine Alewell, Gunnar Lischeid, Klaus Moritz 15 Phyllosphere ecology in a changing environment: the role of insects in forest ecosystems Bernhard Stadler, Beate Michalzik 16 Element fluxes with litterfall in mature stands of Norway spruce and European beech in Bavaria, south Germany Björn Berg, Pedro Gerstberger 17 The role of woody roots in water uptake of mature spruce, beech, and oak trees Julia Lindenmair, Egbert Matzner, Reiner Zimmermann 18 Radial growth of Norway spruce [Picea abies Karst. (L.)] at the Coulissenhieb site in relation to environmental conditions and comparison with sites in the Fichtelgebirge and Erzgebirge Christoph Dittmar, Wolfram Elling Part IV Soil response 19 Environmental controls on concentrations and fluxes of dissolved organic matter in the forest floor and in soil solution Karsten Kalbitz, Tobias Zuber, Ji-Hyung Park, Egbert Matzner 20 Response of soil solution chemistry and solute fluxes to changing deposition rates Egbert Matzner, Tobias Zuber, Gunnar Lischeid 21 Sequestration rates for C and N in soil organic matter at four N-polluted temperate forest stands Björn Berg 22 Riparian zones in a forested catchment: hot spots for microbial reductive processes Kirsten Küsel, Christine Alewell Part V Catchment response 23 Dynamics