title: Changes in the dominant assembly mechanism drive species loss caused by declining resources.
abstract: The species-energy hypothesis predicts that more productive areas support higher species richness. Conversely, when resources are reduced, species richness is reduced. Empirical tests of whether extinctions are predominantly caused by environmental constraints or competitive exclusion are lacking. We experimentally reduced dead wood to c. 15% of the initial amount after a major windstorm and examined changes in assembly mechanisms by combining trait-based and evolutionary species dissimilarities of eight taxonomic groups, differing in their dependence on dead wood (saproxylic/non-saproxylic). Species richness and assembly mechanisms of non-saproxylic taxa remained largely unaffected by removal of dead wood. By contrast, extinctions of saproxylic species were caused by reversing the predominant assembly mechanisms (e.g. increasing importance of competitive exclusion for communities assembled through environmental filtering or vice versa). We found no evidence for an intensification of the predominant assembly mechanism (e.g. competitive exclusion becoming stronger in a competitively structured community).
authors.affiliation: Bavarian Forest National Park, Freyunger Str. 2, 94481, Grafenau, Germany.|Department of Ecology and Ecosystem Management, Chair for Terrestrial Ecology, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, DE-85354, Freising, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Thorn
authors.affiliation: Bavarian Forest National Park, Freyunger Str. 2, 94481, Grafenau, Germany.
authors.forename: Claus
authors.initials: C
authors.lastname: Bässler
authors.affiliation: Institute of Ecology, Friedrich Schiller University Jena, Dornburger Str. 159, 07743, Jena, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Bernhardt-Römermann
authors.affiliation: Department of Biological Sciences, University of Toronto-Scarborough, Toronto, Canada.|Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Canada.|State Key Laboratory of Biocontrol, Key Laboratory of Biodiversity Dynamics and Conservation of Guangdong, Higher Education Institutes, College of Ecology and Evolution, Sun Yat-sen University, Guangzhou, China.
authors.forename: Marc
authors.initials: M
authors.lastname: Cadotte
authors.affiliation: Plant Biodiversity, Department of Ecology and Ecosystem Management, Technische Universität München, Emil-Ramann Strasse 2, 85354, Freising, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Heibl
authors.affiliation: Plant Biodiversity, Department of Ecology and Ecosystem Management, Technische Universität München, Emil-Ramann Strasse 2, 85354, Freising, Germany.
authors.forename: Hanno
authors.initials: H
authors.lastname: Schäfer
authors.affiliation: Bavarian Forest National Park, Freyunger Str. 2, 94481, Grafenau, Germany.|Department of Ecology and Ecosystem Management, Chair for Terrestrial Ecology, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, DE-85354, Freising, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Seibold
authors.affiliation: Bavarian Forest National Park, Freyunger Str. 2, 94481, Grafenau, Germany.|Department of Ecology and Ecosystem Management, Chair for Terrestrial Ecology, Technische Universität München, Hans-Carl-von-Carlowitz-Platz 2, DE-85354, Freising, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Müller
keywords: Dead wood ecology; forest biodiversity; functional traits; phylogenetic diversity; salvage logging; saproxylic