Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome

Citation

Barrio IC, Linden E, te Beest M, Olofsson J, Rocha A, Soininen EM, Alatalo JM, Andersson T, Asmus A, Boike J, Brathen KA, Bryant JP, Buchwal A, Bueno CG & Wookey P (2017) Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome. Polar Biology, 40 (11), pp. 2265-2278. https://doi.org/10.1007/s00300-017-2139-7

Abstract
Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the intensity of invertebrate herbivory on a common tundra plant, the dwarf birch (Betula glandulosa-nana complex), and investigated its relationship to latitude and climate across the tundra biome. Leaf damage by defoliating, mining and gall-forming invertebrates was measured in samples collected from 192 sites at 56 locations. Our results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low intensity. On average, invertebrates damaged 11.2% of the leaves and removed 1.4% of total leaf area. The damage was mainly caused by external leaf feeders, and most damaged leaves were only slightly affected (12% leaf area lost). Foliar damage was consistently positively correlated with mid-summer (July) temperature and, to a lesser extent, precipitation in the year of data collection, irrespective of latitude. Our models predict that, on average, foliar losses to invertebrates on dwarf birch are likely to increase by 6–7% over the current levels with a 1 °C increase in summer temperatures. Our results show that invertebrate herbivory on dwarf birch is small in magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory should be included in predictions of climate change impacts on tundra ecosystems. © 2017 Springer-Verlag GmbH Germany

Keywords
Background insect herbivory; Climate change; Externally feeding defoliators; Latitudinal Herbivory Hypothesis; Leaf damage; Leaf miners; Gall makers; Macroecological pattern

Notes
Additional co-authors: Katherine S. Christie, Yulia V. Denisova, Dagmar Egelkraut, Dorothee Ehrich, LeeAnn Fishback, Bruce C. Forbes, Maite Gartzia, Paul Grogan, Martin Hallinger, Monique M. P. D. Heijmans, David S. Hik, Annika Hofgaard, Milena Holmgren, Toke T. Høye, Diane C. Huebner, Ingibjorg Svala Jonsdottir, Elina Kaarlejarvi, Timo Kumpula, Cynthia Y. M. J. G. Lange, Jelena Lange, Esther Levesque, Juul Limpens, Marc Macias-Fauria, Isla Myers-Smith, Erik J. van Nieukerken, Signe Normand, Eric S. Post, Niels Martin Schmidt, Judith Sitters, Anna Skoracka, Alexander Sokolov, Natalya Sokolova, James D. M. Speed, Lorna E. Street, Maja K. Sundqvist, Otso Suominen, Nikita Tananaev, Jean-Pierre Tremblay, Christine Urbanowicz, Sergey A. Uvarov, David Watts, Martin Wilmking, Heike H. Zimmermann, Vitali Zverev, Mikhail V. Kozlov

Journal
Polar Biology: Volume 40, Issue 11