A. 2001. Recruitment in a Mediterranean annual plant community: seed bank, emergence, litter, and intra-and inter-specific interactions. -Oikos 95: 485-495.Recruitment of reproductive individuals in plant communities is influenced by multiple interacting factors which can be arranged in a number of sequential and distinct stages. Numerous studies have addressed the issue of recruitment in relatively simple conditions under experimental constraints (see Harper 1977, Fenner and Kitajima 1999, Fenner 2000 for extensive reviews). However, it is necessary to approach the subject by testing multiple causal factors within a community context under field conditions. Recruitment of reproductive individuals of annual plants depends chiefly on the abundance of germinable seeds, and emergence and survival of seedlings. Abundance of germinable seeds has been found to be a key factor, particularly in early successional phases (Moore 1980). Under such dynamical conditions, species com-

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Summary1. Some plant functional traits evolved with high temporal resource variability and disturbance in ecosystems where these factors are prevalent. Persistence of characteristics of these functional traits in ecosystems may depend on continued resource variability and disturbance, which in turn may promote functional diversity. In Mediterranean ecosystems, experiments that eliminate temporal resource variability and disturbance are needed to detect functional trait dependence on these factors. 2. The purpose of this study was to experimentally assess how interannual rainfall variability, summer drought and seasonal grazing modify the characteristics of functional traits (life span, flowering time, seed size and plant size) in old-field (6-15 years) Mediterranean herbaceous communities. 3. We designed a 9-year factorial field experiment that manipulated Mediterranean rainfall variability in three ways: (i) constant water availability with no summer drought; (ii) autumn and spring water availability but with summer drought; and (iii) no water supplied to rainfall; and grazing regimes: (i) autumn grazing; (ii) spring grazing; and (iii) non-grazing, in each of the three scenarios of water availability. At a community scale, we measured abundance of different categories within four plant functional traits: plant life span (annual and perennial), flowering time of annuals (spring and summer) and seed and plant sizes of spring annuals (small and large). 4. Interannual rainfall variability in autumn and spring (IRVAS), summer drought and grazing reduced perennial cover. IRVAS was necessary for the persistence of small-seeded and small-size spring annuals. IRVAS and summer drought increased spring annuals in grazed treatments. 5. Results suggest that IRVAS, summer drought and grazing favour the coexistence of species, through improved functional diversity in seed and plant sizes and increased abundance of spring annuals, the most species-rich functional group. Both effects may be the reason for the high species richness in grazed Mediterranean herbaceous communities.

Early succession on large landslides in highly humanized areas that have a tropical dry climate is not well studied. This study documented vegetation recovery during the first 4 years after disturbance at a landslide on Casita Volcano, Nicaragua. We aimed to determine the main pathways and causes of change in community features, such as richness, biovolume, and species composition and verify the role played by environmental heterogeneity. Data consisting on number, covers and mean height of woody species and several abiotic factors related to fertility and stability of substrates were obtained from permanent plots in previously defined zones. Pathways of early succession were highly contingent on abiotic heterogeneity and landscape context and were mainly controlled by abiotic factors associated with fertility of substrates, and incidence of human disturbances. Those results might form the basis of a model of early succession on landslides located in densely populated areas within tropical dry ecosystems. Our results suggest that, rather than focusing research on large-scale disturbances, the study of succession in landslides of the type that occurred on Casita Volcano must point towards the response of ecosystems to a much more complex disturbance regime, in which human-induced disturbances play a major role.

In the last decade, probably in response to global changes and the environmental crisis, the use of the term "social-ecological system" (SES) in scientific literature has grown. This is certainly a sign that the need and importance of transdisciplinary research has been recognized. Here, we explore whether the use of the term is a buzzword or, rather, actually represents a key concept in the integration of social and ecological research. We compiled a database of publications (N = 1289) that mentioned SES in the title, keywords and abstract. Subsequently, we analyzed the authors' affiliations, type of work (conceptual, empirical or review), study site, prevailing human use, temporal and spatial scales of the analysis, kind of variables analyzed (socioeconomic or biophysical), and the method/s used to integrate them. We detected four time spans in the use of the term ). Our results suggest that SES is a widely invoked concept in the study of the interface between social and ecological systems. Most works show some common elements, such as the analysis of resilience, ecosystem services, sustainability, governance and adaptive management. However, the majority of studies do not study SES as a whole, integrating both social and ecological variables and their feedback loops. We consider SES as a concept still in construction in order to build a necessary framework for the integration of social and ecological sciences. For a robust evolution, we recommend that one focus on: (i) A conscious, discussed and agreed effort of scientists to conduct the transdisciplinary research needed to study SES; and (ii) the development of methodological tools for the true integration of social and ecological data.