Plant trait variation has been a transformative tool in plant ecological theory and applications (e.g., conservation and restoration). Functional traits influence plant fitness in response to the abiotic and biotic environment, providing a general means to predict how communities will respond to environmental change across space or time. While efforts have largely explored the utility of adult trait variation related to resource uptake/use, species differences in regeneration success can fundamentally shape population dynamics and community assembly. Post-germination seedling survival (i.e. prior to true leaf emergence) is a critical stage of vulnerability, yet very few efforts have been made to characterize functional differences across species or the implications of this variation for fitness, demography, or community assembly. For the first time, we explored a range of embryonic root and leaf traits and their links to survival across 16 annuals in order to advance our understanding of post-germination ecological strategy and lay a foundation for trait-based inferences during recruitment. We expected to find trait tradeoffs between resource acquisition and conservation across species that were significantly linked to post-germination survival.
Results/Conclusions
We used a range of traits collected in the first four days following germination (elongation rates, widths, and tissue densities of young roots and shoots), trait plasticity in response to water potential, and seedling survival times to assess the extent and implications of post-germination functional variation in 16 annuals of a Mediterranean scrub system. Using multivariate analyses, we characterized trait-based strategies of tissue investment and growth across species. We then used regression to identify links between traits and survival. The data suggest that water availability in the short window around germination can substantially impact the development and growth of young seedlings. However, even within annuals, species varied substantially in post-germination traits and plasticity, which may be important in explaining survival. Our results demonstrate that functional trait variation during regenerative processes can be extensive; while critical recruitment stages are often short-lived, this trait variation is likely to have meaningful implications for how communities assemble.