Patterns of endemism along an elevation gradient in Sierra Nevada (Spain) and Lefka Ori (Crete, Greece)

H Pauli,D Ghosn,A Merzouki,M Gottfried,G Kazakis,J Molero Mesa,R Fernández-Calzado

doi:10.3989/pirineos.2013.168001

Abstract

Aim: High mountains in the Mediterranean region of Europe are particularly rich in endemic vascular plants. We aimed to compare the altitudinal patterns of vascular plant species richness and the proportion of endemic species in two Mediterranean region: Lefka Ori on the island of Crete (Greece) and Sierra Nevada on the Iberian peninsula. Location: Sierra Nevada, Granada (Spain); Lefka Ori, Crete (Greece). Methods: Data from standardised permanent plots settings on summit sites (comprising eight plot sectors, covering the upeermost 10 altitudinal metres) of different elevations were used (GLORIA Multi-Summit approach; www.gloria.ac.at). Species numbers, rates of endemic species, and soils temperature were compared by means of ANCOVA and linear regression. Results: The two regions, though climatically similar, showed strikingly different patterns: In Sierra Nevada, the proportion of endemic vascular plants (species restricted to Sierra Nevada) showed a stepwise increase from the lowest to the highest summit. In contrast, the proportion of endemic species restricted to Crete was not significantly different between the four summits in Lefka Ori. In both regions the observed trends were largely consistent with the altitudinal distribution of the endemic species obtained from standard floras. Main conclusions: The geographic positions of the two regions, i.e. island versus mainland and the higher elevation of Sierra Nevada are suggested to be the primary causes of the observed differences. The high degree of endemism in the cold environments of Mediterranean mountains’ upper bioclimatic zones indicates a pronounced vulnerability to the impacts of climate change. A continued and intensified species monitoring in the mountains around the Mediterranean basin, therefore, should be considered as a priority research task.

Highlights

The degree of endemism of a region’s flora is considered as a measure of the uniqueness of the flora which attracts and inspires botanists and amateurs (Van Der Werff and Consiglio, 2004)
In the present study we focus on altitudinal gradients of vascular plant species richness and the degree of endemism in two Mediterranean mountain ranges with a different geographic situation: Lefka Ori on the island of Crete and Sierra Nevada on the Iberian Peninsula
The proportion of locally endemic species along the full altitudinal gradient shows a distinct increase with elevation in Sierra Nevada from no endemic species at 1500 m to 100% endemics at 3500 m (Fig. 2c), whereas only a weak altitudinal trend was found for Lefka Ori, ranging from 20% endemics between 0 and 500m to and 35-40% endemics above around 2200 m (Fig. 2d)

Summary

Introduction

The degree of endemism of a region’s flora is considered as a measure of the uniqueness of the flora which attracts and inspires botanists and amateurs (Van Der Werff and Consiglio, 2004). Even though vascular plant species richness generally decreases with altitude, Europe’s alpine life zone, covering around 3% of Europe, show a disproportionately high number of species making up approximately 20% of the continents native flora (Väre et al, 2003). This high plant diversity can be attributed to a compression of thermal zones, to high habitat diversity related to rugged topography above the forest line, and to dispersal barriers between mountain ranges supporting divergent speciation. The importance of endemic plants for the mountain vegetation in southern Europe is well documented, e.g. for Crete (Strid, 1993; Dafis et al, 1996; Phitos et al, 1996; Médail and Quézel, 1999; Bergmeier, 2002) or for the Sierra Nevada in southern Spain (Quézel, 1953; Rivas Goday and Mayor López, 1966; Molero Mesa et al,. 1996; Médail and Quézel, 1999; Mota et al, 2002)

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