Ready for change: Seed traits contribute to the high adaptability of mudflat species to their unpredictable habitat

Abstract

Question: A better understanding of species distribution and establishment requires in-depth information on their seed ecology. We hypothesised that seed traits of mudflat species may indicate a strong environmental adaptation in their highly specialised habitat. Furthermore, we asked the question, do seeds of mudflat species have a specific trait value to contribute high adaptability to small-scale variation in their unpredictable habitat?. Location: Central Europe. Methods: Seeds of 30 typical mudflat species were used to measure 15 traits that govern seed dispersal (buoyancy and production), persistence (seed desiccation, mass and persistence in soil), and germination and establishment (germination response to different light, temperature and oxygen conditions). Cluster analysis and phylogenetic principal components analysis (pPCA) were conducted to define potential mudflat species functional groups as per their ecological optima. Results: Seed production and seed mass displayed extremely high variation while seed buoyancy, desiccation and persistence in soil showed almost no variation. All study species produced buoyant, desiccation-tolerant and long-term persistent seeds. Germination and establishment traits also displayed similarity in their responses to different germination treatments as the majority (73%) of species has a moderate seed germination niche width. They germinated well under light/aerobic conditions irrespective to temperature fluctuations. The cluster analysis and pPCA separated species into three potential plant functional groups as ‘true’, ‘flood-resistant’ and ‘facultative’, mudflat species. Conclusion: Moderate variation in the seed traits of mudflat plants suggests they employ different ecological strategies that seem highly predictive to the peculiarity of their specific micro-habitats, which are largely controlled by the hydroperiod gradient. It implies that seed trait information, which further needs to be tested for their adaptability, can advance our understanding of how community composition at the micro-habitat level depends on trait values of participating species.