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1. Despite the disproportionate influence that propagule production, dispersal, seed-to-seedling recruitment and vegetative reproduction can have on plant population and community dynamics, progress has been slow in the directed collection of regeneration traits to inform community assembly outcomes. 2. While seed mass is globally available and linked to growth and reproductive output, there are limits to its explanatory ability. In this essay, we call for expanded efforts to integrate a more diverse set of regeneration traits into community assembly models. 3. First, we extend an existing community assembly framework to conceptualize regeneration as a series of transitional processes whose outcomes are influenced by abiotic filters, biotic interactions and species traits. We then briefly review the literature, highlighting filters and traits of demonstrated or theorized importance for each transition. Finally, we place regeneration in the context of existing and emerging modelling approaches in trait-based community assembly, summarizing key areas of progress needed to integrate regeneration traits into these efforts. 4. Synthesis. By incorporating influential regeneration traits into empirical studies and global data bases, we can begin to disentangle regenerative mechanisms underlying community assembly outcomes and enhance rapidly developing models of species' abundances, distributions and responses to environmental change.

1. Plant defence theory provides a robust framework for understanding interactions between plants and antagonists, and for interpreting broad patterns in the functional‐trait composition of plant communities. However, this framework has been built almost entirely on traits expressed by seedlings and mature plants. 2. No equivalent seed defence theory exists that recognizes the distinct suite of natural enemies that seeds encounter, and the unique constraints to their response. Furthermore, most attention has been paid to insect and vertebrate seed predators active above ground, whereas microbes in soil also have large effects on seed survival, particularly for plants that recruit from soil seed banks. 3. We suggest that concurrent selection on seed dormancy and resistance to microbial antagonists should result in distinct seed defence syndromes. We predict that species with physical seed dormancy will rely on physical defences to exclude predators and pathogens, and rapid seed germination to escape pathogens at the emergence stage. In contrast, species with physiological seed dormancy will deploy a continuum of physical and chemical defences, depending on soil pathogen pressure and duration of seed persistence. Finally, seeds of some species persist in the soil in a non‐dormant, imbibed state, and lack obvious chemical and physical defences. These seeds may be especially dependent upon protection from beneficial seed‐inhabiting microbes. 4. Framing a general ‘seed defence theory' may help to account for the distribution of seed dormancy types across ecosystems. We predict that physiological dormancy will be favoured in dry or well‐drained environments where pathogen pressure is relatively low, germination cues are most unpredictable, and seedling recruitment success is most variable. In contrast, physical dormancy should be favoured in warm and moist environments where pathogen pressure is high, and where germination cues are a stronger predictor of recruitment success. Persistent, non‐dormant seeds are restricted to relatively aseasonal environments where favourable conditions for recruitment can occur over most of the year. 5. Synthesis. Integrating seed defence and dormancy traits can provide new insights into selection on dormancy types, and will help elucidate major trends in seed ecology and evolution. Understanding how seeds are defended also may improve our ability to predict plant regeneration and help develop innovative management strategies for weedy and invasive species.

Seeds of tropical pioneer trees have chemical and physical characteristics that determine their capacity to persist in the soil seed bank. These traits allow seeds to survive in the soil despite diverse predators and pathogens, and to germinate and recruit even decades after dispersal. Defenses in seedlings and adult plants often are described in terms of tradeoffs between chemical and physical defense, but the interplay of defensive strategies has been evaluated only rarely for seeds. Here we evaluated whether classes of seed defenses were negatively correlated across species (consistent with tradeoffs in defense strategies), or whether groups of traits formed associations across species (consistent with seed defense syndromes). Using 16 of the most common pioneer tree species in a neotropical lowland forest in Panama we investigated relationships among four physical traits (seed fracture resistance, seed coat thickness, seed permeability, and seed mass) and two chemical traits (number of phenolic compounds and phenolic peak area), and their association with seed persistence. In addition, seed toxicity was assessed with bioassays in which we evaluated the activity of seed extracts against representative fungal pathogens and a model invertebrate. We did not find univariate tradeoffs between chemical and physical defenses. Instead, we found that seed permeability – a trait that distinguishes physical dormancy from other dormancy types – was positively associated with chemical defense traits and negatively associated with physical defense traits. Using a linear discriminant analysis and a hierarchical cluster analysis we found evidence to distinguish three distinct seed defense syndromes that correspond directly with seed dormancy classes (i.e., quiescent, physical, and physiological). Our data suggest that short and long-term persistence of seeds can be achieved via two strategies: having permeable seeds that are well defended chemically, corresponding to the physiologically dormant defense syndrome; or having impermeable seeds that are well defended physically, corresponding to the physically dormant defense syndrome. In turn, transient seeds appear to have a lower degree of chemical and physical defenses, corresponding to the quiescent defense syndrome. Overall, we find that seed defense and seed dormancy are linked, suggesting that environmental pressures on seed persistence and for delayed germination can select for trait combinations defining distinct dormancy-defense syndromes.

Question: Can seeds in the seed bank be considered as a potential source of material for the restoration of European plant communities including forest, marsh, grassland and heathland? Methods: This study reviews seed bank studies (1990–2006) to determine if they provide useful and reliable results to predict restoration success. We formally selected 102 seed bank studies and analyzed differences between four plant community types in several seed bank characteristics, such as seed density, species richness and similarity between seed bank and vegetation. We also assessed the dominant genera present in the seed bank in each plant community. Results: We observed remarkably consistent trends when comparing seed bank characteristics among community types. Seed density was lowest for grassland and forest communities and highest in marshes, whereas species richness, diversity and evenness of the seed bank community was lowest in heathland and highest in grassland. Similarity between seed bank and vegetation was low in forest, and high in grassland. There was a lot of overlap of the dominant genera of seed bank communities in all studies. Conclusions: The absence of target species and the high dominance of early successional species, in particular Juncus spp., indicate that restoration of target plant communities relying only on seed germination from the seed bank is in most cases not feasible. The exceptions are heathland and early successional plant communities occurring after temporally recurring disturbances. Restoration of plant communities composed of late successional species, such as woody species or herbaceous species typical of woodland or forest rely mainly on seed dispersal and not on in situ germination.

Seed dormancy in plants can have a significant impact on their ecology. Recent work by Rojas-Villa and Quijano-Abril (2023) classified the seed dormancy class in 14 plant species from the Andean forests of Colombia by using germination trials and several microscopy techniques to describe seed anatomy and morphology. The authors conclude that Cecropia species have both physical and physiological dormancy (of which they call physiophysical dormancy) based on seed morphology and mean germination times of over 30 days. Here, we present seed permeability and germination data from neotropical pioneer tree species: Ochroma pyramidale , Cecropia longipes , and Cecropia insignis , as well as Cecropia peltata (present in Rojas-Villa and Quijano-Abril, 2023), to demonstrate that Cecropia species do not exhibit dormancy and also have high levels of seed permeability. We find that the mean germination time for all three Cecropia species in our study was less than 30 days. This suggests a need for reporting the conditions in which germination trials take place to allow for comparability among studies and using seed permeability tests to accurately identify the physical dormancy class of seeds. Further, we present data from the literature that suggests that dormancy is not a requirement for seed persistence in the seed bank.

Background and aims An integrated understanding of the ecophysiological mechanisms of persistence of buried seeds is essential for understanding plant community dynamics and improving our ability to accurately predict seed persistence. However, little is known about how the interaction of precipitation and microorganisms affects persistence of buried seeds and how well seed traits predict seed persistence, especially in a changing environment. Methods Here we determined the combined effect of precipitation and microorganisms on the persistence of buried seeds of 11 species from the Loess Plateau in China, and examined the correlation between seed persistence and seed traits, including seed mass, seed dimensions, seed shape, seed toughness, seed water absorption, total phenolic content, crude protein content and seed longevity. Results Seed persistence of all species decreased with increasing precipitation. Fungicide treatment improved seed persistence of all tested species, while the effect size of fungicide treatment on persistence increased with increasing of precipitation. Persistence was positively correlated with seed longevity (P 50 ), seed toughness and total phenolic content in all treatments. Seed water absorption was not correlated with seed persistence. However, the relationship between seed persistence and seed shape, seed mass, crude protein content, seed germination was strongly dependent on environmental conditions. Conclusions Changes in precipitation not only affected seed persistence but also the relationship between seed persistence and seed traits. Thus, environmental factors should be fully considered in making predictions about seed persistence based on seed traits.

Aims Seeds are usually classified as short- or long-term persistent. It is still hardly understood how environmental conditions influence seed persistence. The study aimed to monitor the long-term effects of different moisture and substrate on seed persistence. Methods Seeds of three Rumex species buried in autumn 2009 in combinations of moisture and substrate were exhumed in spring 2015 and 2021 to test their persistence in the soil after 5.5 and 11.5 years, respectively. Long-term persistence data were compared with data from previous short-term experiment for the same species and environmental conditions reported in Abedi et al. (Plant Soil 374:485-495, 2014). Results No seeds of R.   acetosa were found viable after 1.5 years. Seeds of R.   acetosella retained viability after 11.5 years mostly in dry-loam (~ 60%) and moist-sand (~ 25%) test conditions and moisture levels were identified as the main driver. R.   maritimus retained ≥ 80% viability in moist and wet test conditions and > 40% in the dry test conditions. Conclusions For one ( R. acetosella ) of the three investigated species, the classification of soil seed bank type depended on environmental conditions, emphasizing the need to introduce a more detailed classification scheme for soil seed persistence and to include the information about extrinsic parameters in databases. However, in the other two species with transient ( R. acetosa ) and long-term persistent ( R. maritimus ) seed banks, there are rather intrinsic parameters that affect seed viability. Hence, both site-specific environmental factors as well as seed germination traits need full consideration in the classification of future soil seed bank studies.

Weed emergence time and the longevity of weed seeds within the soil play an important role in implementing a timely and effective weed control program. In this study, the seed longevity and emergence pattern of wild oat (Avena fatua L.) and sterile oat [Avena sterilis ssp. ludoviciana (Durieu) Gillet & Magne] were monitored in field conditions. Fresh seeds of A. fatua and A. ludoviciana were placed into nylon bags (50 seeds per bag in three replications for three locations in eastern Australia: Gatton, Narrabri, and St George) and buried at depths of 0, 2, and 10 cm in November 2017. Bags were exhumed at 6-mo intervals over 30 mo to evaluate seed germination, viability, and decay components. The seed decay component of A. fatua and A. ludoviciana followed an exponential pattern. On both the surface and at the 10-cm burial depth, 50% of the seeds of A. fatua and A. ludoviciana had decayed by 6 mo. The seeds of A. fatua persisted longer at 2-cm depth than at other depths, particularly at St George, where 90% of the seeds decayed after the 30-mo study. However, at Gatton and Narrabri, 90% of the seeds of A. fatua at this depth had decayed after 18 mo of burial in the soil. In the emergence pattern experiment (2017 to 2019), the emergence of A. fatua and A. ludoviciana from different burial depths was also studied. The emergence of A. fatua and A. ludoviciana was greater from 2-cm (29% to 36%) and 5-cm (18% to 43%) soil depths compared with the surface (5% to 10%) and 10-cm (3-9%) soil depth. Avena ludoviciana emerged earlier (2,253 growing degree days [GDD]; March 14, 2018) than A. fatua (3,364 GDD; May 23, 2018). Both species exhibited high emergence between May to June 2018, and the last cohort of each species was observed in October 2018. The highest seedling emergence occurred at the start of the winter season (May), which emphasizes the need for early PRE weed control such as tillage, herbicide application, and cover crops to ensure crops are planted in a clean seedbed. The continued emergence of these weeds into the spring season (October) emphasizes the need for extended periods of A. fatua and A. ludoviciana management. The results also suggest that management strategies that can control all emerged seedlings over 2 yr and restrict seed rain in the field could lead to complete control of Avena spp. in the field.

In temperate plant communities, seed size is often inversely related to seed longevity at the species level. We tested if the inverse relationship between seed size and seed longevity holds among individuals within populations of Ambrosia trifida L. (Asteraceae), a summer annual agricultural weed in the eastern United States Corn Belt that typically emerges in two successive flushes: one before 1 May and one after 1 May. The effects of maternal phenotype on seed morphology, seed weight, late emergence (emergence after 1 May) and seed-bank persistence were determined in two 1-year experiments. All seeds were collected from individuals at weekly intervals for 3 weeks. Sixty seeds per collection were used in the analysis. Despite fluctuating environmental conditions during seed development, seed weight within maternal families remained constant for different maturation times. Differences among families constituted 69% of total variation in seed weight, whereas differences within maternal families composed 31% of the variation in seed weight. Percentage late emergence and percentage seed-bank persistence varied among maternal families. In four maternal families, either 0% or 100% of seedlings emerged after 1 May, but a majority of other maternal families produced seedlings both before and after 1 May. Seed-bank persistence rates ranged from 1 to 51% among maternal families. Percentage late emergence and percentage seed-bank persistence were inversely related to maternal-family mean seed weight in 2006, but not in 2005. These results suggest that the inverse relationship between seed size and seed longevity occurs among individuals of a population, but is affected by the environment.

Salt marshes are highly valuable ecosystems that provide numerous important ecosystem services. Given the global marsh decline, there is a pressing need to understand the natural bottlenecks and thresholds to their establishment and long-term ecological maintenance. Seed presence in the right place and time is a prerequisite for pioneer establishment. We performed field surveys and manipulative seed-bank experiments on 2 mudflats with different levels of exposure in the Westerschelde, The Netherlands, to identify patterns of seed arrival and persistence and their role in determining seed bank abundance. Seed arrival decreased with distance from the seed-source area, i.e. the salt marsh, resulting in seeds being deposited on the mudflat close to the marsh edge. Once arrived, most of the surface seeds were washed away during subsequent tides, with retention of <20%. However, seed burial enhanced seed retention nonlinearly with increasing burial depth. Predation was not a major cause of seed loss. These results point to the importance of hydro dynamic and morphodynamic processes to both lateral seed dispersal and vertical seed burial on tidal flats and, therefore, suggest that saltmarsh establishment and expansion are closely linked to the physical dynamics of the entire estuarine system.