Seed supply, recruitment, and assembly: quantifying relative seed and establishment limitation in a plant community context

There is growing consensus that the relative constraints of seed limitation and establishment limitation in recruitment strongly influence abundance patterns in plant communities. Although these constraints have direct relevance to coexistence, most investigations utilize a seed addition approach that offers limited insight into these dynamics. Here we report results of an assembly experiment with annual plant species of California grasslands to examine how propagule pool characteristics (dominant species abundance, functional diversity) influence establishment and seed limitation (density independence and density dependence across a gradient of seed supply) for each species, and how these constraints affect community diversity. Species were predominantly co-limited by seed and establishment constraints, exhibiting saturating recruitment functions with increased seed supply. Consistent with competition-colonization trade-off predictions, recruitment constraints often depended on the deg...