Recruitment niche segregation of halophytes along the tidal gradient

Abstract

Recruitment is a critical component of the plant life cycle, but little is known about its contribution to community assembly in comparison to later plant stages. We aimed to analyze the relevance of recruitment niche segregation in community assembly using tidal salt marshes in a Mediterranean climate. With this objective, we recorded the spatio-temporal distribution of seedling emergence and its relationships with propagule density and environmental conditions at the community level along the tidal gradient. Results indicate that seedling recruitment was strongly influenced by differential establishment abilities and the effects of sedimentary and meteorological factors that vary seasonally and along the tidal gradient. Taxa colonizing the same habitats showed some similarities in their recruitment patterns, but they also presented enough differences to configure almost a unique recruitment pattern for each taxa. Sediment characteristics segregated recruitment niches at both extremes of the tidal gradient, and the few species colonizing habitats between these two extremes also showed contrasted spatial recruitment patterns. In addition, sequential differences in seedling emergence segregated within high marsh taxa. Most of the taxa exhibited a continuous germination strategy associated to prolonged flowering periods and the ability to germinate along broad salinity ranges. Our results shed light on the importance of recruitment niche segregation to the assembly of plant communities, which is key for understanding their functioning and guiding their management