Résumé
Understanding the population dynamics of rare and endangered plant species is essential to elaborate correct management plans for their conservation. Demographic monitoring of individual species provides valuable information here. However, demographic studies are limited to species for which one can follow individuals through their life history. They are also time consuming, making it difficult to make simultaneous studies of several species with different populations in order to have a more general assessment of rare species dynamics in a given region. In this paper, we illustrate how the use of an approach based on transition frequencies allows for the simultaneous study and comparison of trends in 32 populations of six species with very different life histories and growth forms in the Mediterranean region of the South of France. The results show significant effects of spring rainfall deficit on annual population dynamics but not for perennial species that show a delayed response, and illustrate population declines due to direct human impacts on populations in the study region. Our study illustrates the alarming overall vulnerability of populations and is simple and rapid to apply in a multi-population and multi-species context. It could thus be used by conservation management staff to construct assessments of population vulnerability elsewhere.