Effects of regional climate and small-scale habitat quality on performance in the relict species Ramonda myconi

Abstract

The Mediterranean Basin harbours paleo-endemic species with a highly restricted and fragmented distribution. Many of them might also be of the remnant type, for which the regional dynamics depends on the persistence of extant popu- lations. Therefore, a key issue for the long-term persistence of these species is to assess the variability and effects of ecologi- cal factors determining plant performance. We investigated the spatio-temporal variability in plant traits and ecological factors of Ramonda myconi, a preglacial relict species with remnant dynamics, in 5 populations over 4-7 yr. Ecological factors contributing to fecundity showed a high degree of between-year variability. Pre-dispersal fruit preda- tion had a minor influence on total reproductive output, and most of the variability was found among individuals within populations and years. Spatio-temporal variability in growth and survival was rather low but significant, whereas recruit- ment showed important between-population variability. Among-year variability in fecundity and growth was related to climatic fluctuations on a regional scale, notably rainfall and temperature in a particular period, while the spatial variability in survival and recruitment was explained by within-popula- tion (patch) habitat quality. Although R. myconi is able to withstand repeated periods of drought, water availability seems to be the most important factor affecting plant performance in all the study populations. These findings suggest that the long- term persistence of species showing remnant population dy- namics in habitats under the influence of Mediterranean cli- mate might be threatened by increased aridity as a result of climate change.