- We commonly use trait variation to characterize plant function within and among species and understand how vegetation responds to the environment. Seedling emergence is an especially vulnerable window affecting population and community dynamics, yet trait‐based frameworks often bypass this earliest stage of plant life. Here we assess whether traits vary in ecologically‐meaningful ways when seedlings are just days old. How do shared evolutionary history and environmental conditions shape trait expression, and can traits explain which seedlings endure drought?.
- We measured seedling traits in the first four days of life for 16 annual plant species under two water treatments, exploring trait tradeoffs, species‐level plasticity, and the ability of traits to predict duration of survival under drought.
- Nearly half of traits showed the imprint of evolutionary history (i.e., significant phylogenetic signal), often reflecting differences between grasses and forbs, two groups separated by a deep evolutionary split. Water availability altered trait expression in most cases, though species‐level plastic responses also reflected evolutionary history.
- On average, new seedlings exhibited substantial trait variation structured as multiple tradeoffs like those found in mature plants. Some species invested in thick roots and shoots while others invested in more efficient tissues. Separately, some invested in tougher roots and others in deeper roots. We also observed tradeoffs related to growth rates (fast or slow) and biomass allocation (above or belowground). Drought survival time was correlated most strongly with seed mass, root construction and allocation traits, and phylogeny (grasses versus forbs).
- Synthesis. Our results show that seed and seedling trait variation among annual species is substantial, and that a few attributes could capture major dimensions of ecological strategies during emergence. With seedling survival times ranging two‐fold among annuals (from 7.5 to 14.5 days), these strategies could mitigate recruitment responses to more frequent or longer dry spells. Multivariate trait and plasticity strategies should be further explored in studies designed to assess trait‐fitness linkages during recruitment.
Larson, J.E., Anacker, B.L., Wanous, S. & Funk, J.L. (2020) Ecological strategies begin at germination: traits, plasticity, and survival in the first four days of plant life. Functional Ecology. https://doi.org/10.1111/1365-2435.13543
British Ecological Society
Available for download on Friday, February 05, 2021