Title: A global meta-analysis on fire effects in seed survival, germination and dormancy
Fire is a major disturbance shaping plant traits and vegetation dynamics worldwide. The effects of fire on seed germination and dormancy break are well-established in some ecosystems, but to date there is no attempt to evalute fire effects on regeneration from seed at the global level. I will present the results of a global meta-analysis aiming to determine the effects of high temperatures, smoke and their interactions on seed survival, germination and dormancy. Effect sizes will be compared across ecosystems (forests, savannas, mediterranean-like ecosystems and grasslands), life-forms (grasses, herbs, shrubs, trees and climbers), life-history (annuals vs perennials), regeneration strategy (seeder vs resprouter), seed bank type (soil vs canopy), seed dormancy classes and seed size. Our study has the potential to contribute to a better understanding of regeneration ecology and evolutionary responses of species living in a world with increasing fire frequency.
Fernando Silveira is Professor of Plant Ecology at the Federal University of Minas Gerais, Brazil. He is a broadly trained plant ecologist with a focus on the ecology of seeds. He has developed empirical, theoretical and meta-analytical studies on seed germination, dormancy, dispersal and soil seed banks. His main research line aims to determine the functional role of seeds in structuring plant communities. His study models are ancient, nutrient-poor vegetation associated with rocky outcrops, where he is also trying to use knowledge on seed ecology to better inform restoration practices.
Title: All Seasons Seed Mix - Molecular and Physiological Mechanisms of Seed and Fruit Ecology
Plant seeds are nature's packages that deliver the next generation of plant life across space and time. The team of Prof Gerhard Leubner conducts interdisciplinary research with crop, wild and weed diaspores (seeds and fruits) by integrating approaches from molecular biology and biomechanical engineering to diaspore ecology and environmental simulation. Examples from the Brassicaceae family for the diversity in germination, dormancy and longevity mechanisms will be provided which evolved as adaptations to seasons and erratic weather. Aethionema arabicum provides an excellent model system for studying the role of diaspore bet-hedging to survive unpredictable environments. The large genus Lepidium (cress) provides a diversity of very fascinating mechanisms by which the fruit coat (pericarp) mechanically or chemically imposes dormancy and controls the germination of crop and weed diaspores. Ambient temperature and moisture regimes drive hormonome, epigenome and transcriptome changes underpinning diaspore responses to abiotic and biotic stresses.
Gerhard Leubner is the Chair of Plant Biochemistry and Head of the Seed Science and Technology Group at Royal Holloway University of London. He has more than 25 years’ experience in seed research and is the curator of 'The Seed Biology Place' (www.seedbiology.eu) website. He is the lead PI of the ERA-CAPS Consortium SeedAdapt on dimorphic fruits, seeds and seedlings as bet-hedging adaptation mechanisms to abiotic stress and unpredictable environments (www.seedadapt.eu). More applied projects are into weed ecophysiology and improving crop seed quality and seedling performance is crucial for plant/food value supply chain resilience to climate change.
Title: Extending plant defence theory to seeds
Plant defence theory has developed into a powerful framework for understanding interactions between plants and antagonists, and for the interpretation of the functional trait composition of plant communities. While recent work has begun to develop a trait framework for seeds, only limited experimental work has attempted to elucidate the functional role of key defence traits, their phylogenetic relationships, and interaction with, or constraints on, non-defence traits. We established a common-garden seed burial experiment in seasonally moist tropical forest on Barro Colorado Island, Panama, using 16 common seed-bank forming tree species with contrasting seed dormancy types. We sequenced the fungal communities that infected seeds, assessed their impact on seed survival and germination using inoculation experiments, and measured seed physical traits (seed fracture resistance, seed coat thickness, seed permeability) and chemical traits (phenolic compound diversity, phenolic peak area, activity against fungal pathogens and invertebrates), and their relationship with seed persistence. We found that species differed significantly in the microbial communities that infected them, and in the consequences of experimental inoculation on survival and germination. Furthermore, we found that seed permeability – a trait that distinguishes physical dormancy from other dormancy types – was positively associated with chemical defence traits and negatively correlated with other physical traits. Overall, we found three distinct seed defence syndromes that correspond to three dormancy types (quiescent, i.e., non-dormant; physical; physiological) and that reflect differences in seed persistence in the soil. These results highlight the complexity of seed trait interactions and further reveal how dormancy and defence are related for widespread tropical pioneer tree species. We suggest that using defence theory developed for leaf and whole-plant traits can be used to predict both the functional role of equivalent seed or reproductive traits, and the environmental conditions where these traits should be expressed.
James Dalling is Professor and Head of the Department of Plant Biology at the University of Illinois at Urbana-Champaign. He has worked extensively on the ecology of pioneer tree species in tropical forest, and in particular on seed dispersal, seed germination requirements, and soil seed bank dynamics. He currently focuses on the role of plant-soil and plant-fungal interactions in shaping the composition and diversity of tropical tree communities, with a special interest in understanding how seed-microbial interactions influence seed dormancy and defence traits and contribute to population dynamics.
Title: Perspectives on functional traits in seed ecology
How far seed ecology is integrated into plant functional ecology ? What might we understand by using seed functional traits ? I advocate that a link of seed functional traits to four main plant performances, dispersal, persistence, germination timing and seedling establishment will enable new outcomes in the field. These performances are much less studied than growth, survival and vegetative functional traits, and hence I expect that future studies might reveal new axes of variation in seed ecological functions that are independant from whole plant trait variation. Since dispersal, persistence and timing of germination are crucial functions of how plants react to climatic changes, this knowledge might have strong impact on our current understanding of changes in plant communities and distribution. The development of a seed ecological spectrum based on traits will further help to understand how seed functions and seed traits might be coordinated. I also present some example analyses on a seed germination trait data-base examplifying how trait analysis might contribute to understand seed traits in the context of global plant traits and functions. Finally I recall the need for standardizing seed trait measurment methods and the development of a collaborative project to specifically build a seed functional trait data-base. This talk is based on an international workshop on seed functional traits and its synthesis (Saatkamp et al. 2019).