Altitudinal species richness patterns of vascular plants in the south-eastern Pyrenees and nearby mountains of Catalonia

Abstract

Background: Studying how species richness varies with altitude has become an important part of investigations on mechanisms explaining regional-scale plant species diversity. Altitudinal diversity patterns are poorly known in the Pyrenees and elsewhere in the main mountain massifs in Catalonia (north-eastern Iberian Peninsula).

Aim: We examine the altitudinal patterns of species richness in the Catalan Pyrenees and compare them with those in other mountains in Catalonia. Altitude patterns of species richness in the Pyrenees are compared for functional and taxonomic groups of vascular plants.

Methods: Data on vascular plants were obtained from the Biodiversity Data Bank of Catalonia. We used rarefaction and interpolation to quantify the altitudinal diversity patterns.

Results: The interpolated and rarefied richness generally peaked in the lower part of the altitudinal gradient, but with remarkable variation depending on the taxonomic or functional groups considered. Using all species, there was little variation between the different mountains, but the altitude at which richness started to decrease varied between them.

Conclusions: The pronounced differences among different taxonomic groups and life-forms indicate a strong phylogenetic and adaptive signal on the altitudinal diversity pattern in the Catalan Pyrenees. The lack of regional differences within Catalonia is probably due to small differences in the intensity of climatic gradients across mountains.

Keywords:

• altitudinal gradient
• endemism
• interpolation
• life-forms
• plant species richness
• Pyrenees
• rarefaction

Acknowledgements

We are indebted to all the botanists who have been collecting plants, making observations and identifying samples from the Catalan Pyrenees and other mountainous areas across Catalonia for many decades and whose data made this study possible. We thank all those people who have contributed to building the Biodiversity Data Bank of Catalonia. We also thank Daniel Gómez and Aaron Pérez-Haase for valuable comments on earlier versions of the manuscript, and Eglantine Chappuis for useful discussions on the distribution of hydrophytes. Oriol Grau was funded by a FI fellowship from the Comissionat per a Universitats i Recerca of the Generalitat de Catalunya and the European Social Fund. This study also received financial support from the Spanish Government through the research projects CGL2006-13421-C04-01/BOS (Ministry of Education and Science) and 069/2005 (Ministry of the Environment).