title: Tree diversity does not always improve resistance of forest ecosystems to drought.
abstract: Climate models predict an increase in the intensity and frequency of drought episodes in the Northern Hemisphere. Among terrestrial ecosystems, forests will be profoundly impacted by drier climatic conditions, with drastic consequences for the functions and services they supply. Simultaneously, biodiversity is known to support a wide range of forest ecosystem functions and services. However, whether biodiversity also improves the resistance of these ecosystems to drought remains unclear. We compared soil drought exposure levels in a total of 160 forest stands within five major forest types across Europe along a gradient of tree species diversity. We assessed soil drought exposure in each forest stand by calculating the stand-level increase in carbon isotope composition of late wood from a wet to a dry year (Δδ(13)CS). Δδ(13)CS exhibited a negative linear relationship with tree species diversity in two forest types, suggesting that species interactions in these forests diminished the drought exposure of the ecosystem. However, the other three forest types were unaffected by tree species diversity. We conclude that higher diversity enhances resistance to drought events only in drought-prone environments. Managing forest ecosystems for high tree species diversity does not necessarily assure improved adaptability to the more severe and frequent drought events predicted for the future.
authors.affiliation: Unité Mixte de Recherche 1137, Ecologie et Ecophysiologie Forestiéres, Institut National de la Recherche Agronomique, 54280 Champenoux, France;
authors.forename: Charlotte
authors.initials: C
authors.lastname: Grossiord
authors.affiliation: Unité Mixte de Recherche 1137, Ecologie et Ecophysiologie Forestiéres, Institut National de la Recherche Agronomique, 54280 Champenoux, France;
authors.forename: André
authors.initials: A
authors.lastname: Granier
authors.affiliation: Institut für Spezielle Botanik und Funktionelle Biodiversität, University Leipzig, 04103 Leipzig, Germany;
authors.forename: Sophia
authors.initials: S
authors.lastname: Ratcliffe
authors.affiliation: Forestry Faculty, University of Suceava, 720229 Suceava, Romania;
authors.forename: Olivier
authors.initials: O
authors.lastname: Bouriaud
authors.affiliation: Institute of Biology/Geobotany and Botanical Garden, Martin Luther University Halle Wittenberg, 06108 Halle, Germany; German Centre for Integrative Biodiversity Research, 04103 Leipzig, Germany;
authors.forename: Helge
authors.initials: H
authors.lastname: Bruelheide
authors.affiliation: Faculty of Biology, Bialowieza Geobotanical Station, University of Warsaw, 17-230 Bialowieza, Poland;
authors.forename: Ewa
authors.initials: E
authors.lastname: Chećko
authors.affiliation: Faculty of Environment and Natural Resources, Freiburg University, 79108 Freiburg, Germany;
authors.forename: David Ian
authors.initials: DI
authors.lastname: Forrester
authors.affiliation: Department of Geosciences and Natural Resource Management, University of Copenhagen, 1958 Copenhagen, Denmark;
authors.forename: Seid Muhie
authors.initials: SM
authors.lastname: Dawud
authors.affiliation: Finnish Forest Research Institute, 80101 Joensuu, Finland;
authors.forename: Leena
authors.initials: L
authors.lastname: Finér
authors.affiliation: Department of Agri-Food and Environmental Sciences, Section of Soil and Plant Science, University of Florence, 50144 Florence, Italy;
authors.forename: Martina
authors.initials: M
authors.lastname: Pollastrini
authors.affiliation: Faculty of Biology/Geobotany, University Freiburg, 79104 Freiburg, Germany;
authors.forename: Michael
authors.initials: M
authors.lastname: Scherer-Lorenzen
authors.affiliation: Museo Nacional de Ciencias Naturales, Consejo Superior de Investigaciones Cientificas, E-28006 Madrid, Spain;
authors.forename: Fernando
authors.initials: F
authors.lastname: Valladares
authors.affiliation: Unité Mixte de Recherche 1137, Ecologie et Ecophysiologie Forestiéres, Institut National de la Recherche Agronomique, 54280 Champenoux, France; bonal@nancy.inra.fr.
authors.forename: Damien
authors.initials: D
authors.lastname: Bonal
authors.affiliation: Long-Term Forest Ecosystem Research, Swiss Federal Institute for Forest, Snow and Landscape Research, 8903 Birmensdorf, Switzerland; and Berlin-Brandenburg Institute of Advanced Biodiversity Research, 14195 Berlin, Germany.
authors.forename: Arthur
authors.identifier: http://orcid.org/0000-0002-1910-9589
authors.initials: A
authors.lastname: Gessler
mesh_terms: D044822:Biodiversity; D002247:Carbon Isotopes; D055864:Droughts; D065928:Forests; D013045:Species Specificity; D013312:Stress, Physiological; D014197:Trees / Q000502:physiology*
chemical_list: D002247:Carbon Isotopes
keywords: FundivEUROPE; carbon isotope composition; climate change; ecology; species interaction