Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in:Journal of Vegetation Science 26.3 (2015): 538-551 DOI: http://dx.doi.org/10.1111/jvs.12260
Copyright: © 2014 International Association for Vegetation ScienceEl acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscription to upper and lower topographic zones) in two years with contrasting rainfall conditions. 19Community weighted mean (CWM) and Rao quadratic entropy for three key plant ecology 20 strategy traits (specific leaf area, height and seed mass) were calculated for each community. We 21 used null models to estimate functional richness (FR) and functional divergence (FD), the two 22 components of functional diversity with the highest power to detect changes in community 23 assembly processes across environmental gradients. 24Results: The patterns of CWM remained rather constant across years, with the only exception 25 being seed mass, which experienced considerable temporal changes that suggested that heavy-26 seeded species are favored under stressful conditions. Marked and unchanging differences in FR 27 between the two habitats revealed the existence of trait convergence -observed for vegetative 28 traits in unproductive habitats and seed mass in productive ones-and divergence -seed mass in 29 unproductive habitats and vegetative traits in productive ones-for different niche axes. In 30 contrast, the patterns of FD of the vegetative traits changed considerably between years. 31Conclusions: Increased water availability during the wet year had a greater impact on the 32 functional structure of unproductive habitats. The appearance of taller species in unproductive 33 habitats during the wet year suggested a relaxation of the abiotic filters. In addition, differences 34 in the direction of the interannual changes of FD indicated that increased competition for light 35 can lead to increased niche partitioning in unproductive habitats, but also to the exclusion of 36 weak competitors in undisturbed productive sites. Our results show that the temporal changes in 37 the abundance of the species of Mediterranean grasslands largely depend on the species' traits, 38 leading to great interannual changes in its functional structure, and that the patterns of trait 39 convergence/divergence are, not only trait-dependent, but also depend on the complex 40 interaction between productivity and disturbance. 41