Large-scale grazing history effects on Arctic-alpine germinable seed banks Victoria T. Gonza ´lez • Kari Anne Bra ˚then • Virve T. Ravolainen • Marianne Iversen • Snorre B. Hagen Received: 16 February 2009 / Accepted: 6 October 2009 / Published online: 17 October 2009 Ó Springer Science+Business Media B.V. 2009 Abstract Grazing constitutes a selective pressure on vegetation recruitment through modification of the seed banks. Here we address changes in seed bank density and its life history trait composition in century- old pastures, where contrasting reindeer densities have developed during the last decades. We cover the actual scales used by these wide-roaming herbi- vores by sampling 70 productive tundra habitats over 7,421 km 2 in the reindeer summer pastures of North- ern Norway. Results showed that the seed bank density was significantly lowered where reindeer densities had increased in recent decades, whereas the century-long history of grazing probably explains the main seed bank traits typical of grazing tolerant plants. The dominant trait characteristics were small seeds ( \ 0.5 mg), seeds lacking dispersal mechanism and individuals with a graminoid growth form. Finally, differences between regions introduced trait variation independent of grazing history, reinforcing the impor- tance of using scales covering several contexts when designing ecological studies. Keywords Reindeer (Rangifer tarandus) Á Growth form Á Seed mass Á Diaspore morphology Á Temporal scale Á Spatial scale Á Context dependency Introduction Seed bank accumulation is one of the most important strategies for plant survival and propagation in disturbed and variable environments, such as grazed ecosystems (Chambers and Macmahon 1994). It is well documented that the vertebrate grazing changes the seed abundance and species composition of the seed banks (e.g., Chippindale and Milton 1934; O’Connor and Pickett 1992; Jutila 1998; Mayor et al. 2003; Sternberg et al. 2003; Eskelinen and Virtanen 2005). However, studies on seed bank trait composition in relation to grazing are few, in spite of the scientific evidence showing that plant life history traits influence plant tolerance to grazing (Diaz et al. 2001; Sternberg et al. 2003). Electronic supplementary material The online version of this article (doi:10.1007/s11258-009-9676-2) contains supplementary material, which is available to authorized users. V. T. Gonza ´lez (&) Á K. A. Bra ˚then Á V. T. Ravolainen Á S. B. Hagen Department of Biology, University of Tromsø, 9037 Tromsø, Norway e-mail: victoria.gonzalez@uit.no K. A. Bra ˚then e-mail: kari.brathen@uit.no V. T. Ravolainen e-mail: virve.ravolainen@uit.no S. B. Hagen e-mail: snorre.hagen@uit.no M. Iversen Sami College, Ha ´nnuluohkka ´ 45, 9520 Guovdageaidnu/ Kautokeino, Norway e-mail: marianne.iversen@samiskhs.no 123 Plant Ecol (2010) 207:321–331 DOI 10.1007/s11258-009-9676-2