Assessing Intraspecific Variation in Effective Dispersal Along an Altitudinal Gradient: A Test in Two Mediterranean High-Mountain Plants

n August and September 2010, we established 10x10m plots in five populations of both S. ciliata and A. caespitosa distributed along an altitudinal gradient in the in the orophyllous cryophilic pastures of Sierra de Guadarrama, a mountain range located in central Spain. In each study plot, we mapped every S. ciliata and A. caespitosa reproductive plant and seedling using a high-resolution Differential Global Navigation Satellite System (DGNSS) (Viva GS15, Leica, Switzerland) with an accuracy of 5 cm for x and y coordinates. We also measured plant diameter and the number of inflorescences of every reproductive plant. To account for potential seedling sources outside the study area, we also recorded the location, diameter and number of inflorescences of reproductive plants in a buffer zone of two meters around the plots.