University of Oulu

Virtanen, R, Clark, AT, den Herder, M, Roininen, H. Dynamic effects of insect herbivory and climate on tundra shrub growth: Roles of browsing and ramet age. J Ecol. 2021; 109: 1250– 1262.

Dynamic effects of insect herbivory and climate on tundra shrub growth : roles of browsing and ramet age

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Author: Virtanen, Risto1,2,3; Clark, Adam Thomas2,3,4; den Herder, Michael5;
Organizations: 1Ecology & Genetics, University of Oulu, Oulu, Finland
2Department of Physiological Diversity, Helmholtz Center for Environmental Research – UFZ, Leipzig, Germany
3German Centre for Integrative Biodiversity Research (iDiv) Halle‐Jena‐Leipzig, Leipzig, Germany
4Institute of Biology, Karl‐Franzens University of Graz, Graz, Austria
5European Forest Institute, Joensuu, Finland
6Department of Environmental and Biological Sciences, University of Eastern Finland, Joensuu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 23.5 MB)
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Language: English
Published: John Wiley & Sons, 2021
Publish Date: 2021-04-09


1. To predict shrub responses under climate change in tundra, we need to understand how thermal conditions and herbivory contribute to growth. We hypothesise that shrub growth increases with thermal conditions and precipitation, but that this increase is counteracted by insect herbivory, and that these climate–insect herbivory relationships are modified by both browsing and plant age.

2. We use empirical dynamic modelling (EDM) to analyse a 20‐year time series on willow Salix phylicifolia shoot growth, growing degree days, summer precipitation and herbivory from an experiment at forest–tundra ecotone. The experiment includes manipulations of avian and mammal browsing (fences) and ramet age (pruning to rejuvenate willows).

3. Negative effects of insect herbivory on willow shoot growth were intensified during warmer years, whereas increasing precipitation led to reduced effects. Moreover, the effect of insect herbivores on shoot growth varied with ramet age and vertebrate browsing: younger ramets generally experienced less negative insect herbivore effects, whereas ptarmigan browsing was associated with more positive temperature effects on shoot growth, and reindeer browsing with more negative effects of insect herbivory and precipitation.

4. Synthesis. Our findings show that the negative effects of insect herbivory on shoot growth likely intensify under warmer thermal conditions, but that increasing precipitation can counteract these effects. Moreover, changes in thermal conditions, precipitation and vertebrate browsers all have predictable, albeit complex and nonlinear, effects on shrub growth, highlighting the importance of long‐term experimental data and flexible analytical methods such as EDM for characterising climate and community interactions in artic systems.

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Series: Journal of ecology
ISSN: 0022-0477
ISSN-E: 1365-2745
ISSN-L: 0022-0477
Volume: 109
Issue: 3
Pages: 1250 - 1262
DOI: 10.1111/1365-2745.13551
Type of Publication: A1 Journal article – refereed
Field of Science: 1172 Environmental sciences
1181 Ecology, evolutionary biology
Funding: This research has been supported by grants of Academy of Finland (project #259072), Maj and Tor Nessling Foundation, and University of Oulu Arctic Interactions funding (to A.T.C.). We thank Matt Ayres and two anonymous reviewers for useful comments on the manuscript. We also thank Helena Hakkarainen for assistance in the growth measurements in 2004, and the Metsähallitus and Kilpisjärvi Biological Station for providing logistic support during field work. HELMHOLTZ‐ZENTRUM FUR UMWELTFORSCHUNG UFZ, Blended DEAL: ProjektDEAL. Open Access funding enabled and organized by ProjektDEAL.
Academy of Finland Grant Number: 259072
Detailed Information: 259072 (Academy of Finland Funding decision)
Copyright information: © 2020 The Authors. Journal of Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial‐NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non‐commercial and no modifications or adaptations are made.