REVIEWS Ecological Monographs, 83(4), 2013, pp. 419–439 Ó 2013 by the Ecological Society of America The past ecology of Abies alba provides new perspectives on future responses of silver fir forests to global warming WILLY TINNER, 1,2,3,11 DANIELE COLOMBAROLI, 1,2 OLIVER HEIRI, 1,2 PAUL D. HENNE, 1,2,3 MARCO STEINACHER, 2,4 JOHANNA UNTENECKER, 5 ELISA VESCOVI, 1,2 JUDY R. M. ALLEN, 6 GABRIELE CARRARO, 7 MARCO CONEDERA, 8 FORTUNAT JOOS, 2,4 ANDRE ´ F. LOTTER, 9 JU ¨ RG LUTERBACHER, 5 STE ´ PHANIE SAMARTIN, 1,2 AND VERUSHKA VALSECCHI 10 1 Paleoecology, Institute of Plant Sciences, University of Bern, Altenbergrain 21, CH-3013 Bern, Switzerland 2 Oeschger Centre for Climate Change Research, University of Bern, Zachringerstrasse 25, CH-3012 Bern, Switzerland 3 Forest Ecology, Institute of Terrestrial Ecosystems, ETH Zurich, Universita ¨tstrasse 16, CH-8092 Zurich, Switzerland 4 Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, CH-3012 Bern, Switzerland 5 Climatology, Climate Dynamics and Climate Change, Department of Geography, Justus Liebig University of Giessen, Senckenbergstrasse 1, D-35390 Giessen, Germany 6 School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE United Kingdom 7 Dionea SA, Environmental Consulting, CH-6600 Locarno, Switzerland 8 Insubric Ecosystems, Swiss Federal Institute for Forest, Snow and Landscape Research WSL, via Belsoggiorno 22, CH-6500 Bellinzona, Switzerland 9 Paleoecology, Department of Physical Geography, Utrecht University, Budapestlaan 4, NL-3584 CD Utrecht, The Netherlands 10 Institute of Evolution Sciences, CNRS, Place Euge `ne Bataillon, F-34090 Montpellier, France Abstract. Paleoecology can provide valuable insights into the ecology of species that complement observation and experiment-based assessments of climate impact dynamics. New paleoecological records (e.g., pollen, macrofossils) from the Italian Peninsula suggest a much wider climatic niche of the important European tree species Abies alba (silver fir) than observed in its present spatial range. To explore this discrepancy between current and past distribution of the species, we analyzed climatic data (temperature, precipitation, frost, humidity, sunshine) and vegetation-independent paleoclimatic reconstructions (e.g., lake levels, chironomids) and use global coupled carbon-cycle climate (NCAR CSM1.4) and dynamic vegetation (LandClim) modeling. The combined evidence suggests that during the mid-Holocene (;6000 years ago), prior to humanization of vegetation, A. alba formed forests under conditions that exceeded the modern (1961–1990) upper temperature limit of the species by ;5–78C (July means). Annual precipitation during this natural period was comparable to today (.700–800 mm), with drier summers and wetter winters. In the meso-Mediterranean to sub-Mediterranean forests A. alba co-occurred with thermophilous taxa such as Quercus ilex, Q. pubescens, Olea europaea, Phillyrea, Arbutus, Cistus, Tilia, Ulmus, Acer, Hedera helix, Ilex aquifolium, Taxus, and Vitis. Results from the last interglacial (ca. 130 000–115 000 BP), when human impact was negligible, corroborate the Holocene evidence. Thermophilous Mediterranean A. alba stands became extinct during the last 5000 years when land-use pressure and specifically excessive anthropogenic fire and browsing disturbance increased. Our results imply that the ecology of this key European tree species is not yet well understood. On the basis of the reconstructed realized climatic niche of the species, we anticipate that the future geographic range of A. alba may not contract regardless of migration success, even if climate should become significantly warmer than today with summer temperatures increasing by up to 5–78C, as long as precipitation does not fall below 700–800 mm/yr, and anthropogenic disturbance (e.g., fire, browsing) does not become excessive. Our finding contradicts recent studies that projected range contractions under global-warming scenarios, but did not factor how millennia of human impacts reduced the realized climatic niche of A. alba. Key words: Abies alba; bioclimatic envelope models; climate models; climatic niche; dynamic vegetation models; global change; paleoclimatology; paleoecology; realized niche. INTRODUCTION Paleoecology can provide essential insights about the long-term impacts of changing climate, disturbance, and land-use regimes on species and ecosystems. Manuscript received 21 December 2012; revised 15 March 2013; accepted 18 March 2013. Corresponding Editor: A. W. D’Amato. 11 E-mail: willy.tinner@ips.unibe.ch 419