title: Climate Change Impairs Nitrogen Cycling in European Beech Forests.
abstract: European beech forests growing on marginal calcareous soils have been proposed to be vulnerable to decreased soil water availability. This could result in a large-scale loss of ecological services and economical value in a changing climate. In order to evaluate the potential consequences of this drought-sensitivity, we investigated potential species range shifts for European beech forests on calcareous soil in the 21st century by statistical species range distribution modelling for present day and projected future climate conditions. We found a dramatic decline by 78% until 2080. Still the physiological or biogeochemical mechanisms underlying the drought sensitivity of European beech are largely unknown. Drought sensitivity of beech is commonly attributed to plant physiological constraints. Furthermore, it has also been proposed that reduced soil water availability could promote nitrogen (N) limitation of European beech due to impaired microbial N cycling in soil, but this hypothesis has not yet been tested. Hence we investigated the influence of simulated climate change (increased temperatures, reduced soil water availability) on soil gross microbial N turnover and plant N uptake in the beech-soil interface of a typical mountainous beech forest stocking on calcareous soil in SW Germany. For this purpose, triple 15N isotope labelling of intact beech seedling-soil-microbe systems was combined with a space-for-time climate change experiment. We found that nitrate was the dominant N source for beech natural regeneration. Reduced soil water content caused a persistent decline of ammonia oxidizing bacteria and therefore, a massive attenuation of gross nitrification rates and nitrate availability in the soil. Consequently, nitrate and total N uptake of beech seedlings were strongly reduced so that impaired growth of beech seedlings was observed already after one year of exposure to simulated climatic change. We conclude that the N cycle in this ecosystem and here specifically nitrification is vulnerable to reduced water availability, which can directly lead to nutritional limitations of beech seedlings. This tight link between reduced water availability, drought stress for nitrifiers, decreased gross nitrification rates and nitrate availability and finally nitrate uptake by beech seedlings could represent the Achilles' heel for beech under climate change stresses.
authors.affiliation: Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany.|Institute of Forest Sciences, Chair of Tree Physiology, University of Freiburg; Georges-Koehler-Allee 53/54, 79110 Freiburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Dannenmann
authors.affiliation: Lehrstuhl für Bodenkunde, Department für Ökologie und Ökosystemmanagement, Wissenschaftszentrum Weihenstephan. Technische Universität München, 85350 Freising-Weihenstephan, Germany.
authors.forename: Carolin
authors.initials: C
authors.lastname: Bimüller
authors.affiliation: Environmental Genomics, Helmholtz Zentrum München, German Research Center for Environmental Health, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
authors.forename: Silvia
authors.initials: S
authors.lastname: Gschwendtner
authors.affiliation: Forest Botany and Tree Physiology, Büsgen-Institute, Georg-August Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Leberecht
authors.affiliation: Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany.
authors.forename: Javier
authors.initials: J
authors.lastname: Tejedor
authors.affiliation: Institute of Forest Sciences, Chair of Tree Physiology, University of Freiburg; Georges-Koehler-Allee 53/54, 79110 Freiburg, Germany.
authors.forename: Silvija
authors.initials: S
authors.lastname: Bilela
authors.affiliation: Institute of Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Gasche
authors.affiliation: Chair of Forestry Economics and Forest Planning, University of Freiburg, 79110 Freiburg, Germany.|Research Unit Forest Resources and Management, Swiss Federal Research Institute WSL, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland.
authors.forename: Marc
authors.initials: M
authors.lastname: Hanewinkel
authors.affiliation: Research Unit Forest Resources and Management, Swiss Federal Research Institute WSL, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland.
authors.forename: Andri
authors.initials: A
authors.lastname: Baltensweiler
authors.affiliation: Lehrstuhl für Bodenkunde, Department für Ökologie und Ökosystemmanagement, Wissenschaftszentrum Weihenstephan. Technische Universität München, 85350 Freising-Weihenstephan, Germany.|IAS-Institute for Advanced Study, Technische Universität München, Lichtenbergstraße 2a, D-85748 Garching, Germany.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Kögel-Knabner
authors.affiliation: Forest Botany and Tree Physiology, Büsgen-Institute, Georg-August Universität Göttingen, Büsgenweg 2, 37077 Göttingen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
authors.affiliation: Environmental Genomics, Helmholtz Zentrum München, German Research Center for Environmental Health, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Schloter
authors.affiliation: Institute of Forest Sciences, Chair of Tree Physiology, University of Freiburg; Georges-Koehler-Allee 53/54, 79110 Freiburg, Germany.
authors.forename: Judy
authors.initials: J
authors.lastname: Simon
authors.affiliation: Institute of Forest Sciences, Chair of Tree Physiology, University of Freiburg; Georges-Koehler-Allee 53/54, 79110 Freiburg, Germany.|King Saud University, PO Box 2454, Riyadh 11451, Saudi Arabia.
authors.forename: Heinz
authors.initials: H
authors.lastname: Rennenberg
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D002980:Climate; D057231:Climate Change; D003198:Computer Simulation; D055864:Droughts; D005060:Europe; D029964:Fagus / Q000378:metabolism*; D065928:Forests; D006358:Hot Temperature; D038821:Mycorrhizae / Q000254:growth & development; D009584:Nitrogen / Q000378:metabolism*; D058458:Nitrogen Cycle / Q000502:physiology*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics; D012987:Soil / Q000737:chemistry; D014197:Trees / Q000378:metabolism*
chemical_list: D012987:Soil; D000641:Ammonia; D010088:Oxidoreductases; C045582:ammonia monooxygenase; D009584:Nitrogen