Recruitment limitation – the failure of a species to establish recruits at an available site – is a potential determinant of plant communities’ structure, causing local communities to be a limited subset of the regional species pool. Recruitment limitation results from three mechanisms: i) lack of seed sources (i.e., source limitation), ii) failure of available seeds to reach recruitment sites (i.e., dispersal limitation), and iii) failure of arrived seeds to establish at a location (i.e., establishment limitation). Here, we evaluated the relative importance of these mechanisms in three co-occurring tree species (Dipteryx oleifera, Attalea butyracea, and Astrocaryum standleyanum) that share seed dispersers/predators. The study was set up on Barro Colorado Island (Panama) at 62 1-ha sites with varying tree densities. Source limitation was estimated as the proportion of sites that would be reached by seeds if seeds were distributed uniformly. Dispersal limitation was estimated from the number of sites with seeds in the soil bank. Establishment limitation was evaluated by measuring germination and 1-year survival in seed addition experiments. The effect of conspecific and heterospecific densities on the mechanisms was evaluated at three spatial scales (1, 5 and 9 ha). For all species, seed predation was the most important recruitment component (~80% decrease in seed survival). Establishment varied among species and was affected by conspecific and heterospecific species densities across spatial scales. Given that species identity, distribution and seed dispersal/predation affect recruitment at multiple scales, multiscale studies are required to understand how recruitment limitation determines community structure in tropical forests.

Extent: 62 1ha site located at Barro Colorado Island (Panama)

Species: Attalea butyracea, Astrocaryum standleyanum and Dipteryx oleifera

• Tree mapping using aerial imagery and ground surveys
• Seed density and predation: soil survey in the first 10cm of soil looking for seeds of the species studied
• Seed germination: Seed addition experiment and survey after 4 months and 12 months to record germination and survival.