Minimum winter temperature reconstruction from average earlywood vessel area of European oak (Quercus robur) in N-Poland C. Pritzkow a , T. Wazny b , K.U. Heußner c , M. Słowiński d , A. Bieber a , I. Dorado Liñán e , G. Helle a , I. Heinrich a,f, ⁎ a Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences Climate Dynamics and Landscape Evolution, Potsdam, Germany b Institute for the Study, Restoration and Conservation of Cultural Heritage, Nicolaus Copernicus University, Torun, Poland c Scientific Department of the Head Office, Deutsches Archäologisches Institut, Berlin, Germany d Dep. of Environmental Resources and Geohazard, Institute of Geography, Polish Academy of Sciences, Torun, Poland e Forest Research Centre, Instituto Nacional de Investigación y Tecnología Agrariay y Alimentaria (INIA-CIFOR), 28040 Madrid, Spain f Humboldt University Berlin, Geography Department, Berlin, Germany abstract article info Article history: Received 15 June 2015 Received in revised form 30 January 2016 Accepted 23 February 2016 Available online xxxx Tree-ring-based temperature reconstructions form a substantial part of the international proxy data base used to examine and model global climate variations of the last Millennium. However, most tree-ring-based reconstruc- tions are derived from study sites in the high latitudes or high altitudes, paying very little attention to low eleva- tion sites. Thus, a large gap in the geographical coverage of climate reconstructions from temperate low elevation sites in central Europe still exists. This motivated us to concentrate our efforts on the European oak (Quercus robur) in N-Poland. We developed a new robust tree-ring width chronology (TRW), as well as four wood anatom- ical chronologies (e.g. average vessel area and number of vessels) from Q. robur for the period 1810 to 2010. The chronologies were examined for their climatological responses. While TRW was found to have weak correlations with climate, the earlywood vessel parameters (EVP), especially average vessel area (AVA), revealed significant positive correlations to minimum winter temperatures. Based on stable climate–growth correlations, a recon- struction of minimum winter temperatures (29th November to 20th January) back to 1810 was performed for north Poland. The reconstruction indicates a promising potential to reveal low-frequency climate information. An additional extreme year analysis suggested that in cold winters, a cold–warm–cold pattern in the minimum temperatures was responsible for the relatively small earlywood vessels. Spatial field correlations imply that our reconstruction is more related to temperature variations towards the east of Europe. The reconstructed temper- ature compared well with two existing temperature reconstructions, especially during most of the 20th century, even though the temperature reconstructions differ spatially and temporally. Based on these findings, the rela- tively extensive resource of archeological oak material from this region may be useful to perform multicentennial climate reconstructions in the temperate climate zone. © 2016 Elsevier B.V. All rights reserved. Keywords: Wood anatomy Earlywood vessel parameter Quercus robur Temperature reconstruction Dendroclimatology Temperate lowlands Poland 1. Introduction Climate reconstructions based on tree rings are mainly derived from sites with extreme climates at high latitudes or altitudes (Gagen et al., 2006). The closer a tree grows to its distribution limits, the stronger is the influence of one principal climate parameter mainly limiting growth (Fritts, 1966; Hughes, 2002). Dendroclimatology uses this strong relation between climate and tree rings to generate robust climate proxies. Since forests cover large parts of the continental earth surface, theoretically, dendroclimatological studies may facilitate climate recon- structions almost everywhere. However, in reality, the climate signal strengths implemented in tree-ring parameters such as tree-ring width (TRW) are often not strong enough for reconstructions at sites with less extreme climate conditions (Buckley et al., 1997), and thus most temperature reconstructions are from remote and sparsely populated regions where the climate–growth relations are less diffuse (Young et al., 2012). In order to challenge this geographical imbalance concerning tree- ring-based climate reconstructions, new dendroclimatological parame- ters such as stable isotopes (Gagen et al., 2006; Treydte et al., 2007) and wood cell structures (Fonti et al., 2010) were established as new proxies in dendroclimatology studies. Recent studies revealed the large poten- tial of stable isotopes and quantitative wood anatomy for high-quality dendrochronological reconstructions to overcome such geographical restrictions to extreme sites only (Fonti et al., 2010; Young et al., 2012). By analyzing conifers growing in the temperate lowland forests of southern Australia (Drew et al., 2011) and northeastern Germany Palaeogeography, Palaeoclimatology, Palaeoecology xxx (2016) xxx–xxx ⁎ Corresponding author at: Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences Climate Dynamics and Landscape Evolution, Potsdam, Germany. Tel.: +49 331 2881915; fax: +49 331 2881302. E-mail address: heinrich@gfz-potsdam.de (I. Heinrich). PALAEO-07721; No of Pages 11 http://dx.doi.org/10.1016/j.palaeo.2016.02.046 0031-0182/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo Please cite this article as: Pritzkow, C., et al., Minimum winter temperature reconstruction from average earlywood vessel area of European oak (Quercus robur) in N-Poland, Palaeogeogr. Palaeoclimatol. Palaeoecol. (2016), http://dx.doi.org/10.1016/j.palaeo.2016.02.046