Spatial diversity of recent trends in Mediterranean tree growth

Abstract

Increasing temperatures and shifting precipitation regimes define the Mediterranean Basin (MB) as one of the world's most sensitive climate change hot spots. Among various ecological effects, disruptions in the growth-climate response of Mediterranean forest species have been recently observed. Complex topographical and climatological factors, however, may result in contrasting patterns of recent tree growth, with their biotic and abiotic drivers often remaining debatable. Here, we compile dendrochronological evidence from 878 cases at 645 sites reported in 66 peer-reviewed publications to assess modern (post-1970) growth trends across the MB (30°-46° N and 10° W-40° E). This collection mainly reveals positive trends in temperate environments across the northwestern part of the Basin, whereas negative trends were often found at xeric sites in the southwestern and eastern regions. Although these response patterns are indicative for both beneficial as well as detrimental effects of climate change on pan-Mediterranean forest ecosystem function and productivity, our review is slightly biased by selective sampling efforts that focused on higher elevations and older trees within a few countries in the northwest. This imbalance emphasizes the need for more evenly distributed study sites and age classes that better reflect ecological rather than political and methodological criteria. © 2014 IOP Publishing Ltd. ; We thank three anonymous reviewers for their insightful comments which helped us to improve a preliminary version of the manuscript. We also thank Linda Feichtinger (WSL) for her assistance in R scripting, and Franco Biondi and Jordi Martínez-Vilalta for providing us with geographical information regarding their publications included in this review. UB was supported by the Czech project 'Building up a multidisciplinary scientific team focused on drought' (No. CZ.1.07/2.3.00/20.0248). We also acknowledge the support of projects 012/2008 and 387/2011 (OAPN, Spain). ; Peer Reviewed