Herbivory on the pedunculate oak along an urbanization gradient in Europe : Effects of impervious surface, local tree cover, and insect feeding guild

14 páginas, 3 figuras
Urbanization is an important driver of the diversity and abundance of tree-associated insect herbivores, but its consequences for insect herbivory are poorly understood. A likely source of variability among studies is the insufficient consideration of intra-urban variability in forest cover. With the help of citizen scientists, we investigated the independent and interactive effects of local canopy cover and percentage of impervious surface on insect herbivory in the pedunculate oak (Quercus robur L.) throughout most of its geographic range in Europe. We found that the damage caused by chewing insect herbivores as well as the incidence of leaf-mining and gall-inducing herbivores consistently decreased with increasing impervious surface around focal oaks. Herbivory by chewing herbivores increased with increasing forest cover, regardless of impervious surface. In contrast, an increase in local canopy cover buffered the negative effect of impervious surface on leaf miners and strengthened its effect on gall inducers. These results show that-just like in non-urban areas-plant-herbivore interactions in cities are structured by a complex set of interacting factors. This highlights that local habitat characteristics within cities have the potential to attenuate or modify the effect of impervious surfaces on biotic interactions.
This study was carried out with financial support from the French National Research Agency (ANR) in the frame of the Investments for the Future Programme, within the Cluster of Excellence COTE (Continental To coastal Ecosystems: evolution, adaptability, and governance) (ANR-10-LABX-45) and was further funded by the BNP Paribas Foundation as part of its Climate & Biodiversity Initiative the citizen science project Tree Bodyguards. The authors warmly thank all the young European citizens and their teachers who made this study possible. They also thank the professional scientists who kindly agreed to participate in this study: Alexander Kozel (Belarusian State Technological University and American Psychological Association), Andreas Schuldt (Forest Nature Conservation, Georg-August-University Göttingen, Göttingen, German), Aurélien Sallé (Laboratoire de Biologie des Ligneux et des Grandes Cultures, INRAE, Université d'Orléans), Chloe Mendiondo and Claire Colliaux (Department of Agroecology, Aarhus University, Flakkebjerg Research Centre, DK-4200 Slagelse, Denmark), György Csóka (Department of Forest Protection, NARIC Forest Research Institute, Mátrafüred, Hungary), Lars Opgennoorth (Biodiversity and Conservation Biology, Ecological Genetics, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland), Laurent Augusto (INRAE, Bordeaux Sciences Agro), Marija Popović (Faculty of Forestry, University of Belgrade, Belgrade, Serbia), Mickael Pihain (Research Unit “Ecosystèmes, Biodiversité, Evolution”, University of Rennes 1/CNRS, 35042 Rennes, France), Olivier Bouriaud (Applied Ecology Laboratory, Forestry Faculty, “Ștefan cel Mare, University of Suceava, Suceava, Romania), Stefan K. Müller (Freie evangelische Schule Lörrach), Tomas Roslin (Department of Ecology; Swedish University of Agricultural Sciences), Valentin Queloz (Forest Entomology, Swiss Federal Research Institute WSL), and Vojtech Lanta (Institute of Botany CAS, Dukelská 135, 37901 Třeboň, Czech Republic). They also thank Michael Scherer-Lorenzen (Geobotany, Faculty of Biology, University of Freiburg) for the help during the coordination of the research.