Functional traits shape plant-plant interactions and recruitment in a hotspot of woody plant diversity

Abstract

SummaryUnderstanding and predicting recruitment in species-rich plant communities requires identifying the functional determinants of both density-independent performance and interactions.In a common-garden field experiment with 25 species of the woody plant genusProtea, we varied the initial spatial and taxonomic arrangement of seedlings and followed their survival and growth during recruitment. Neighbourhood models quantified how six key functional traits affect density-independent performance, interaction effects and responses.Trait-based neighbourhood models accurately predicted individual survival and growth from the initial spatial and functional composition of species-rich experimental communities. Functional variation among species caused substantial variation in density-independent survival and growth that was not correlated with interaction effects and responses. Interactions were spatially-restricted but had important, predominantly competitive, effects on recruitment. Traits increasing the acquisition of limiting resources (water for survival, soil P for growth) mediated a trade-off between competitive effects and responses. Moreover, resprouting species had higher survival but reduced growth, likely reinforcing the survival-growth trade-off in adult plants.The combination of field experiments and trait-based neighbourhood analyses holds substantial potential for community ecology. It permits the identification of traits that mediate performance trade-offs promoting coexistence in species-rich communities and contributes key knowledge to guide conservation and restoration of biodiversity hotspots.