Abstract
AbstractAimThe Mediterranean Basin is a major hotspot of plant biodiversity, including forest trees. Over the past centuries, Mediterranean forests have been fragmented and over‐exploited, to which the threats of climate change are now added. Our aim is to better understand patterns and processes of tree biodiversity in the Mediterranean and to provide indicators complementing the traditional approaches to biodiversity conservation based on species counts and occurrences, using georeferenced phylogenetic diversity and endemism analyses in a spatial ecological context.LocationMediterranean Europe.MethodsUsing a dated phylogeny of the 64 Euro‐Mediterranean tree genera, we calculated phylogenetic diversity for all 50 × 50 km2 grid cells spanning Mediterranean Europe (n = 643) and compared values with those obtained for genus‐level taxonomic diversity. Then, we tested the relative influence of geography, past and present climate, and soil on tree diversity (phylogenetic or taxonomic) and its geographical turnover. Geographical patterns of phylogenetic endemism were inferred using the Categorical Analyses of Neo‐ and Paleo‐Endemism (CANAPE) methodology.ResultsWe showed that phylogenetic and taxonomic diversity within and among cells are correlated and influenced by soil parameters as well as current, Holocene and Late Glacial Maximum climate. Southern Spain, Cyprus and some Aegean islands contained areas of disproportionately high phylogenetic diversity and a concentration of phylogenetic paleo‐endemics, while phylogenetic neo‐endemism was high in eastern Sicily. Mixed phylogenetic endemism regions were detected in southern Spain and Portugal, in the Balkans and in Crete.Main conclusionsOur phylogenetic approach provides relevant indicators for better protecting forests of the Mediterranean, encompassing past and present evolutionary processes and factors. We consider areas that show a concentration of evolutionary history manifested by high phylogenetic endemism as high priority targets for the conservation of the European tree flora.
Highlights
Forests and woodlands harbour immense terrestrial and aquatic biodiversity and represent one of the most species-rich habitat type worldwide (Gibson et al, 2011; Lindenmayer, 2009)
Our study identified 76 grid cells of high phylogenetic endemism (22 paleo-endemism, 10 neo-endemism, 40 mixed- endemism, 4 super-endemism), 38 situated in the western and 38 in the eastern Mediterranean Basin, which mostly match regions considered as regional hotspots of plant biodiversity (Médail & Quézel, 1997; Vela & Benhouhou, 2007) and are refugia-rich in the study of Médail and Diadema (2009) (Figure 7)
The high concentration of mixed phylogenetic endemism that we identified in northern Greece and the Belasca mountains of Bulgaria, and of super-endemism in a few Greek Aegean Islands (Samothraki, Amorgos) were neither detected as regional hotspots of plant biodiversity by Médail and Quézel (1997) or as refugia by Médail and Diadema (2009)
Summary
Forests and woodlands harbour immense terrestrial and aquatic biodiversity and represent one of the most species-rich habitat type worldwide (Gibson et al, 2011; Lindenmayer, 2009). Our specific goal was to single out regions of high phylogenetic neo- and paleo-endemism, thereby increasing our knowledge of biodiversity spatial patterns and of the ecological factors that can explain their emergence, as well as contributing to prioritizing areas of high conservation value. For this aim, we (a) calculated a series of taxonomic and phylogenetic diversity indices for each of the 50 × 50 km grid cells (n = 643) covering the entire European part of the Mediterranean Basin; (b) quantified among-cell variation and identified the main environmental factors explaining genus turnover and (c) calculated grid cell level phylogenetic endemism indicators using the Categorical Analyses of Neo-and Paleo-Endemism (CANAPE) methodology
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