Methods for measuring arctic and alpine shrub growth: A review Isla H. Myers-Smith a , Martin Hallinger b,q , Daan Blok c , Ute Sass-Klaassen d , Shelly A. Rayback e , Stef Weijers f , Andrew J. Trant g , Ken D. Tape h , Adam T. Naito i , Sonja Wipf j , Christian Rixen j , Melissa A. Dawes j , Julia A. Wheeler j , Agata Buchwal k , Claudia Baittinger l , Marc Macias-Fauria m , Bruce C. Forbes n , Esther Lévesque o , Noémie Boulanger-Lapointe o,1 , Ilka Beil b , Virve Ravolainen p , Martin Wilmking b, ⁎ a School of GeoSciences, University of Edinburgh, Edinburgh EH9 3JW, United Kingdom b Institute of Botany and Landscape Ecology, Ernst-Moritz-Arndt University Greifswald, D-17487 Greifswald, Germany c Center for Permafrost (CENPERM), University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen, Denmark d Forest Ecology and Management Group, Wageningen University, PO 47, NL-6700 AA Wageningen, Netherlands e Department of Geography, University of Vermont, 213 Old Mill Building, 94 University Place, Burlington, VT 05405, USA f Climatology and Landscape Ecology, Department of Geography, University of Bonn, Meckenheimer Allee 166, D-53115 Bonn, Germany g School of Environmental Studies, University of Victoria, PO Box 3060 STN CSC, Victoria, British Columbia V8W 3R4, Canada h Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA i Department of Geography, Texas A&M University, 810 Eller O&M Building, Mailstop 3147 TAMU, College Station, TX 77843-3147, USA j WSL Institute for Snow and Avalanche Research SLF, Fluelastrasse 11, CH-7260 Davos Dorf, Switzerland k Institute of Geoecology and Geoinformation, Adam Mickiewicz University, Dziegielowa 27, 61-680 Poznan, Poland l Environmental Archaeology and Materials Science, National Museum of Denmark, Frederiksholms Kanal 12, DK-1220 Copenhagen, Denmark m Long-term Ecology Laboratory, Biodiversity Institute, Oxford Martin School & Department of Zoology, University of Oxford, Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK n Arctic Centre, University of Lapland, Box 122, FI-96101 Rovaniemi, Finland o Département des sciences de l'environnement, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada p Department of Arctic and Marine Biology, University of Tromsø, N-9037 Tromsø, Norway q Department of Ecology, Swedish University of Agricultural Sciences, 75651 Uppsala, Sweden abstract article info Article history: Received 8 April 2014 Accepted 16 October 2014 Available online 22 October 2014 Keywords: Shrub Dendroecology Dendrochronology Growth rings Stem increments Tundra Shrubs have increased in abundance and dominance in arctic and alpine regions in recent decades. This often dra- matic change, likely due to climate warming, has the potential to alter both the structure and function of tundra ecosystems. The analysis of shrub growth is improving our understanding of tundra vegetation dynamics and en- vironmental changes. However, dendrochronological methods developed for trees, need to be adapted for the morphology and growth eccentricity of shrubs. Here, we review current and developing methods to measure ra- dial and axial growth, estimate age, and assess growth dynamics in relation to environmental variables. Recent advances in sampling methods, analysis and applications have improved our ability to investigate growth and re- cruitment dynamics of shrubs. However, to extrapolate findings to the biome scale, future dendroecological work will require improved approaches that better address variation in growth within parts of the plant, among indi- viduals within populations and between species. © 2014 Elsevier B.V. All rights reserved. Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Important botanical considerations of shrub species . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.1. Growth form . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.2. Longevity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.3. Below-ground connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Sampling of individuals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3.1. Accounting for herbivory and human impact . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Sampling within shrub patches and along the stem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. Growth deformities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Earth-Science Reviews 140 (2015) 1–13 ⁎ Corresponding author. E-mail address: wilmking@uni-greifswald.de (M. Wilmking). 1 Current address: Department of Geography, University of British Columbia, 1984 West Mall, Vancouver, BC Canada V6T 1Z2, Canada. http://dx.doi.org/10.1016/j.earscirev.2014.10.004 0012-8252/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Earth-Science Reviews journal homepage: www.elsevier.com/locate/earscirev