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Background and Aims Some plants germinate their seeds enclosed by a pericarp, whereas others lack the outer packaging. As a maternal tissue, the pericarp might impart seeds with different germination strategies. Plants in a community with different flowering times might separately disperse and germinate their seeds; therefore, flowering time can be considered as one manifestation of maternal effects on the offspring. The mass of the seed is another important factor influencing germination and represents the intrinsic resource of the seed that supports germination. Using seeds from a species-rich alpine meadow located in the Hengduan Mountains of China, a global biodiversity hotspot, we aimed to illustrate whether and how the type of seed (with or without a pericarp) modulates the interaction of flowering time and seed mass with germination. Methods Seeds were germinated in generally favourable conditions, and the speed of germination [estimated by mean germination time (MGT)] was calculated. We quantified the maternal conditions by separation of flowering time for 67 species in the meadow, of which 31 produced seeds with pericarps and 36 yielded seeds without pericarps. We also weighed 100 seeds of each species to assess their mass. Key Results The MGT varied between the two types of seeds. For seeds with pericarps, MGT was associated with flowering time but not with seed mass. Plants with earlier flowering times in the meadow exhibited more rapid seed germination. For seeds without a pericarp, the MGT depended on seed mass, with smaller seeds germinating more rapidly than larger seeds. Conclusions The distinct responses of germination to flowering time and seed mass observed in seeds with and without a pericarp suggest that germination strategies might be mother-reliant for seeds protected by pericarps but self-reliant for those without such protection. This new finding improves our understanding of seed germination by integrating ecologically mediated maternal conditions and inherent genetic properties. [ABSTRACT FROM AUTHOR]

In many regions, the climate is changing faster during winter than during the other seasons, and a loss of snow cover combined with increased temperature variability can expose overwintering organisms to harmful conditions. Understanding how species respond to these changes during critical developmental times, such as seed germination, helps us assess the ecological implications of winter climate change. To address this concern, we measured the breaking of seed dormancy and cold tolerance of temperate grassland species in the lab and field. In the lab, we ran germination trials testing the tolerance of 17 species to an extreme cold event. In the field, we deployed seeds of two species within a snow manipulation experiment at three locations and measured germination success biweekly from seeds subjected to ambient and reduced snow cover from winter into spring. From lab trials, cold tolerance varied among species, with seed germination decreasing <10%–100% following extreme cold events. Cold tolerance was related to seed traits, specifically less round seeds, seeds that required cold stratification, and seeds that mature later in the season tended to be more impacted by extreme cold temperatures. This variation in seed cold tolerance may contribute to altered community composition with continued winter climate change. In the field, germination increased through late winter, coinciding with the accumulation of days where temperatures were favorable for cold stratification. Through spring, germination success decreased as warm temperatures accumulated. Collectively, species‐specific seed cold tolerances and mortality rates may contribute to compositional changes in grasslands under continued winter climate change. [ABSTRACT FROM AUTHOR]

Reproduction by perennial plants varies from being relatively constant over years to the production of massive and synchronous seed crops at irregular intervals, a reproductive strategy called mast seeding. The sources of interspecific differences in the extent of interannual variation in seed production are largely unknown. We conducted a global meta‐analysis of animal‐dispersed species to quantify how the interannual variability in seed crops produced by plants can be explained by the seed mass, dispersal mode, phylogeny, and climate. Phylogenetic analysis indicated that the interannual variations in seed production and seed mass tended to be similar in related species due to their shared evolution. The interannual variation in seed production was 1.22 times higher in synzoochorous species dispersed by scatter‐hoarders compared with endozoochorous species dispersed by frugivores. Furthermore, the production of small seeds was associated with higher interannual variation in seed production, although synzoochorous species produced larger seeds than endozoochorous species. Precipitation rather than temperature had a significant positive effect on the interannual variation in seed production. The seed mass and dispersal mode contributed more to the interannual variation in seed production than phylogeny, climate, and fruit type. Our findings support a long‐standing hypothesis that interspecific variation in the masting intensity is largely shaped by interactions between plants and animals. [ABSTRACT FROM AUTHOR]

Premise of research. Seed ontogeny between fertilization and seed maturity is a neglected life history stage in demographic studies, yet this period may have profound consequences for seed set and seedling vigor. For plant species with multiovulate linear fruits, it is possible to record the relative position of each ovule, thereby allowing investigators to assess whether ovule development occurs at random or whether it exhibits unique discernible patterns within fruits. We studied effects of ovule position on patterns of ovule development, seed mass, and seedling size within linear pods of Cercis canadensis. Methodology. Fruits were collected from multiple trees at each of three sites in southeastern Michigan. Intraovary ovule position and developmental fate (i.e., undeveloped ovule, aborted ovule, insect-damaged seed, and mature seed) and seed mass were determined. Seedling performance from three seed size classes was also monitored. Seedling traits included days to emergence, height, leaf area, and seedling biomass. Pivotal results. Three-fourths or more of all ovules within fruits across the populations reached seed maturity. Patterns of seed maturation and abortion were nonrandom and significantly depended on populations, individuals, and ovule positions within fruits. Probability of seed maturation within individual fruits was lowest at the basal end and highest at either the center or the distal end, suggesting the existence of a fertilization gradient. Conversely, frequencies of undeveloped ovules and aborted seeds were highest at the bases of fruits. Insect-damaged seeds accounted for 1%–3% of all ovules and occurred randomly. Seeds located in basal sections of fruits were also smaller than seeds located in central and distal sections. Seed mass was positively correlated with all measures of seedling performance. Conclusions. Patterns of ovule development and seed maturation were determined to be nonrandom within fruits of C. canadensis. Ovule position influences abortion and maturation of seeds, seed mass, and early seedling vigor and has the potential to affect overall plant fitness. [ABSTRACT FROM AUTHOR]

Seed germination and dispersal have an important impact on the establishment and spread of invasive plants. Understanding the extent of intraspecific seed trait variations can enhance our understanding of how invasive plants respond to environmental change after introduction and help predict the dynamic of invasive species under future environmental conditions. However, less attention has been given to the variation in seed traits within species as opposed to among species. We compared seed production, seed morphological traits, dispersal ability, and seedling performance of Chromolaena odorata from 10 introduced populations in Asia and 12 native populations in America in a common garden. The results showed that range (introduced vs. native) and climate affected these traits. Compared with the native population, the introduced populations had higher seed numbers per capitula, lighter seeds, and higher potential dispersal ability seeds (lower terminal velocity) but lower germination rates and seedling lengths. Climatic clines in seed numbers per capitula and pappus length were observed; however, the clines in pappus length differed between the introduced and native populations. Trait covariation patterns were also different between both ranges. In the native populations, there was a trade-off between seed numbers per capitula and seed mass, while this relationship was not found for the introduced populations. These results indicate that C. odorata alters the ecological strategy of seed following invasion, which facilitates its establishment and fast dispersal and contributes to successful invasion in the introduced ranges. [ABSTRACT FROM AUTHOR]

Several ecological filters in deforested and degraded areas reduce seedling emergence and establishment and hinder ecological restoration by direct seeding. Understanding whether functional traits are related to a species' capacity to overcome these filters and predict their field performance might improve the success of direct seeding techniques for ecological restoration. We assessed eight seed functional traits of tropical tree species, seeking those that best explained their establishment success in direct seeding restoration projects. We analyzed a dataset from 52 studies that tested direct seeding techniques with tree species in Brazil. From each study, we collected the mean establishment percentage for all tree species. Seed mass, cotyledon function, and germination speed were the only functional traits that significantly affected the species establishment percentage in direct seeding restoration projects. Species with larger seeds, storage cotyledons, and faster germination had higher establishment percentages. Choosing species with these functional traits for seed mixes will provide higher establishment percentages and, consequently, improve restoration success by direct seeding techniques. [ABSTRACT FROM AUTHOR]

There is some evidence that seed traits can affect the long-term persistence of seeds in the soil. However, findings on this topic have differed between systems. Here, we brought together a worldwide database of seed persistence data for 1474 species to test the generality of seed mass–shape–persistence relationships. We found a significant trend for low seed persistence to be associated with larger and less spherical seeds. However, the relationship varied across different clades, growth forms and species ecological preferences. Specifically, relationships of seed mass–shape–persistence were more pronounced in Poales than in other order clades. Herbaceous species that tend to be found in sites with low soil sand content and precipitation have stronger relationships between seed shape and persistence than in sites with higher soil sand content and precipitation. For the woody plants, the relationship between persistence and seed morphology was stronger in sites with high soil sand content and low precipitation than in sites with low soil sand content and higher precipitation. Improving the ability to predict the soil seed bank formation process, including burial and persistence, could benefit the utilization of seed morphology–persistence relationships in management strategies for vegetation restoration and controlling species invasion across diverse vegetation types and environments. [ABSTRACT FROM AUTHOR]

A fundamental challenge in the field of ecology involves understanding the adaptive traits and life history stages regulating the population dynamics of species across diverse habitats. Seed traits and early seedling vigor are thought to be key functional traits in plants, with important consequences for recruitment, establishment, and population persistence. However, little is known about how diverse seed traits interact with seed and microsite availability to impact plant populations. Here, we performed a factorial experiment involving seed addition and surface soil disturbance to explore the combined effects of seed and site availability using genotypes characterized by varying seed mass and dormancy traits. Additionally, we included hybrids that exhibited recombined seed trait relationships compared with natural genotypes, allowing us to assess the impact of specific seed traits on establishment across different sites. We detected a significant three-way interaction between seed addition, site conditions, and soil surface disturbance, influencing both seedling establishment and adult recruitment in Panicum hallii , a perennial grass found in coastal mesic (lowland) and inland xeric (upland) habitats. This establishment/recruitment pattern suggests that mesic and xeric establishment at foreign sites is constrained by the interplay of seed and site limitations. Notably, soil surface disturbance facilitated establishment and recruitment of the xeric genotype while limiting the mesic genotype across all sites. Our results highlight the importance of seed size and dormancy as key factors impacting seedling establishment and adult recruitment, suggesting a potential interactive relationship between these traits. [ABSTRACT FROM AUTHOR]

Simple Summary: Animal-mediated seed dispersal plays a crucial role in the regeneration of plant populations and the stability of forest ecosystems. In this study, we used the tagging method to measure the effects of seeds of different sizes at different frequencies on seed fate and dispersal distance. We found that rodents consumed more small seeds in situ, dispersed and scatter-hoarded more large seeds, and dispersed large seeds over longer distances. Rodents showed a negative frequency dependence for small seeds and a positive frequency dependence for large seeds on being eaten in situ. Moreover, rodents showed a negative frequency dependence for large seeds and a positive frequency dependence for small seeds on being eaten after removal and scatter-hoarding. These findings provide insights into the frequency dependence of animal predation on seed size, animal-mediated seed dispersal, and the regeneration of plant populations. Frequency-dependent predation is common in predator–prey interactions. Size is an important characteristic of seeds and is crucial in the regeneration stage of plant seeds. However, the frequency dependence of animal predation on seed size has not been reported. In this study, we conducted a field experiment and used different sizes of Liaodong oak (Quercus wutaishanica) seeds to test the frequency dependence of intraspecific seed size selection in rodents. We used the number ratio of large to small seeds as the frequency. The results show that the rate of small seeds being eaten in situ was significantly higher than that of large seeds (p < 0.05). The rates of different-sized seeds being eaten after removal decreased with increasing frequencies, and there was no significant difference between frequencies except for 1:9 and 9:1. The rates of large seeds being scatter-hoarded were significantly higher than those of small seeds at different frequencies (p < 0.05). The eating distances after removal of large seeds were significantly longer than those of small seeds at the same frequencies (p < 0.05). Furthermore, the scatter-hoarding distances of large seeds were significantly longer than those of small seeds at three frequencies (1:9, 3:7, and 9:1) (p < 0.05). That is, rodents consumed more small seeds in situ, dispersed and scatter-hoarded more large seeds, and dispersed large seeds over longer distances. Rodents exhibited a negative frequency dependence for small seeds and a positive frequency dependence for large seeds on being eaten in situ. Moreover, rodents exhibited a negative frequency dependence for large seeds and a positive frequency dependence for small seeds on being eaten after removal and scatter-hoarding. These results reveal the frequency dependence of rodent selection on seed size and provide new insights into animal-mediated seed dispersal and the regeneration of plant populations. [ABSTRACT FROM AUTHOR]

Plants interact extensively with their neighbors, but the evolutionary consequences of variation in neighbor identity are not well understood. Seedling traits are likely to experience selection that depends on the identity of neighbors because they influence competitive outcomes. To explore this, we evaluated selection on seed mass and emergence time in two California grasses, the native perennial Stipa pulchra and the non-native annual Bromus diandrus, in the field with six other native and non-native neighbor grasses in single and mixed species treatments. We also quantified characteristics of each neighbor treatment to further investigate factors influencing their effects on fitness and phenotypic selection. Selection favored larger seeds in both focal species and this was largely independent of neighbor identity. Selection generally favored earlier emergence in both focal species, but neighbor identity influenced the strength and direction of selection on emergence time in S. pulchra but not B. diandrus. Greater light interception, higher soil moisture, and greater productivity of neighbors was associated with more intense selection for earlier emergence and larger seeds. Our findings suggest that changes in plant community composition can alter patterns of selection in seedling traits, and that these effects can be associated with measurable characteristics of the community.

Several high-elevation plant species would experience an increased risk of regional extinction due to various climatic and anthropogenic factors. Information about the effects of climate change is urgently needed for modeling vegetation dynamics because it influences the various seed parameters like seed germination, seed maturation, seed mass, and seed bank in the soil. The present study was conducted at an elevation of 3145–3560 m in the treeline area of the western Himalayan region of India. The change in seed color is correlated with other seed parameters such as seed moisture content, seed germination, seed mass, and seed fall density. A decline in moisture content in maturing seeds is closely related to seed maturity (p < 0.05). Quercus semecarpifolia contains the highest seed mass followed by Abies spectabilis. Reportedly, the species with higher seed mass have an advantage in light-restricted environments for seed germination and seedling development. In addition, the fruit mass was observed to be the highest for Rhododendron campanulatum, while both Betula utilis and R. arboreum had similar fruit mass. The seed fall density varied between 1.55 and 7.85 seeds m–2 and the maximum mortality of up to 32% of seedlings was observed during post-monsoon season from November to February. The potential disruption in the timing of seed fall, soil seed bank, and seed germination due to climatic irregularities has broader implications for forest ecosystems. Generally, the soil in treeline areas gets frozen during winter, resulting in seedlings facing severe water stress and a high rate of transpiration. The present study addresses the issue regarding the survival and proliferation of important treeline species in the western Himalayan region of India.

Abstract: Aim: To determine the relationships between the functional trait composition of forest communities and environmental gradients across scales and biomes and the role of species relative abundances in these relationships. Location: Global. Time period: Recent. Major taxa studied: Trees. Methods: We integrated species abundance records from worldwide forest inventories and associated functional traits (wood density, specific leaf area and seed mass) to obtain a data set of 99,953 to 149,285 plots (depending on the trait) spanning all forested continents. We computed community‐weighted and unweighted means of trait values for each plot and related them to three broad environmental gradients and their interactions (energy availability, precipitation and soil properties) at two scales (global and biomes). Results: Our models explained up to 60% of the variance in trait distribution. At global scale, the energy gradient had the strongest influence on traits. However, within‐biome models revealed different relationships among biomes. Notably, the functional composition of tropical forests was more influenced by precipitation and soil properties than energy availability, whereas temperate forests showed the opposite pattern. Depending on the trait studied, response to gradients was more variable and proportionally weaker in boreal forests. Community unweighted means were better predicted than weighted means for almost all models. Main conclusions: Worldwide, trees require a large amount of energy (following latitude) to produce dense wood and seeds, while leaves with large surface to weight ratios are concentrated in temperate forests. However, patterns of functional composition within‐biome differ from global patterns due to biome specificities such as the presence of conifers or unique combinations of climatic and soil properties. We recommend assessing the sensitivity of tree functional traits to environmental changes in their geographic context. Furthermore, at a given site, the distribution of tree functional traits appears to be driven more by species presence than species abundance.

Functional traits can have intraspecific and interspecific variations essential in the structure and dynamics of natural communities. These traits may have implications in the germination and seedling establishment phases in seeds. The objective of this study was to evaluate the effect of variations in mass, volume, and nutrient content (C, N, and P) on the germination of eight species representative of the tropical dry forest (TDF). Our results showed that seed size, both in terms of mass and volume, did not predict germination rates or percentages, nor were they related to nutrient content. In contrast, N content was the most important trait in the germination phase. Larger seeds did not germinate more or faster, but they could offer better resistance against desiccation, since they had higher C/N ratios in their tissues, a characteristic of orthodox seeds. The species A. guachapele, B. arborea, H. crepitans, and V. tortuosa presented a high biological potential in terms of their regeneration capacity, particularly, because the characteristics of their seeds, as well as the nutrient content, revealed consistent implications in their reproductive success, promoting high germination percentages in less time. In general, the results obtained in this study provide basic knowledge for future research, offering starting points for further exploration of species-specific adaptations and how they may be affected by the environment. [ABSTRACT FROM AUTHOR]

Animal-mediated seed dispersal is very important for plant population regeneration and the stability of forest ecosystems. Seed size and cache density are important factors for seed dispersal, but we still know little about seed size selection at different cache densities. Here, we conducted field experiments in a Larix principis-rupprechtii plantation in the Liupan Mountains in Ningxia province to investigate the effects of tag-marked Quercus wutaishanica seeds of different sizes and cache densities on predation and the scatter-hoarding behavior of rodents. The results showed lower proportions of intact in situ (IIS) and eaten in situ (EIS) large seeds than small seeds at all levels of cache density, with the exception of IIS seeds at a 6.25 seed·m−2 cache density. A higher proportion of small seeds were eaten after removal (EAR), but a higher proportion of large seeds were scatter-hoarded (SH) by rodents at most cache densities. Furthermore, rodents preferentially removed large seeds farther away for eating or scatter-hoarding. The IIS and EIS proportions of both large and small seeds declined, but the proportion of the two types of seeds that were EAR fluctuated, increasing with increasing cache density. Rodents preferred to increase the proportion of scatter-hoarding of large seeds with increasing cache density, whereas the proportion of scatter-hoarding of small seeds was maximized at a cache density of 6.25 seed·m−2. Both the eaten distance after removal (EDAR) and scatter-hoarded distance (SHD) increased with increasing cache density. These results suggest that large seeds are more likely to be scatter-hoarded and removed to longer distances than small ones. Rodents tended to reduce the seed proportion of EIS seeds and increased the proportion of seeds EAR and SH, and accordingly increased EDAR and SHD with increasing cache density. This study provides some scientific basis for animal-mediated seed dispersal. [ABSTRACT FROM AUTHOR]

Aim: To determine the relationships between the functional trait composition of forest communities and environmental gradients across scales and biomes and the role of species relative abundances in these relationships. Location: Global. Time period: Recent. Major taxa studied: Trees. Methods: We integrated species abundance records from worldwide forest inventories and associated functional traits (wood density, specific leaf area and seed mass) to obtain a data set of 99,953 to 149,285 plots (depending on the trait) spanning all forested continents. We computed community‐weighted and unweighted means of trait values for each plot and related them to three broad environmental gradients and their interactions (energy availability, precipitation and soil properties) at two scales (global and biomes). Results: Our models explained up to 60% of the variance in trait distribution. At global scale, the energy gradient had the strongest influence on traits. However, within‐biome models revealed different relationships among biomes. Notably, the functional composition of tropical forests was more influenced by precipitation and soil properties than energy availability, whereas temperate forests showed the opposite pattern. Depending on the trait studied, response to gradients was more variable and proportionally weaker in boreal forests. Community unweighted means were better predicted than weighted means for almost all models. Main conclusions: Worldwide, trees require a large amount of energy (following latitude) to produce dense wood and seeds, while leaves with large surface to weight ratios are concentrated in temperate forests. However, patterns of functional composition within‐biome differ from global patterns due to biome specificities such as the presence of conifers or unique combinations of climatic and soil properties. We recommend assessing the sensitivity of tree functional traits to environmental changes in their geographic context. Furthermore, at a given site, the distribution of tree functional traits appears to be driven more by species presence than species abundance. [ABSTRACT FROM AUTHOR]

Background: Considering the growing demand for plant trait data and taking into account the lack of trait data from Eastern Europe, especially from its steppic region, we launched a new Ukrainian Plant Trait Database (UkrTrait v. 1.0) aiming at collecting all the available plant trait data from Ukraine. To facilitate further use of this database, we linked the trait terminology to the TRY Plant Trait Database, Thesaurus of Plant Characteristics (TOP) and Plant Trait Ontology (TO). For taxa names, we provide the crosswalks between the Ukrainian checklist and international sources, i.e. GBIF Backbone Taxonomy, World Checklist of Vascular Plants (World Checklist of Vascular Plants (World Checklist of Vascular Plants (WCVP), World Flora Online (WFO) and Euro+Med PlantBase. We aim to integrate our data into the relevant global (TRY Plant Trait Database) and pan-European (FloraVeg.EU) databases. The current version of the database is freely available at the Zenodo repository and will be updated in the future. New information: Until now, plant traits for the Ukrainian flora were scattered across literature, often focusing on single species and written mainly in Ukrainian. Additionally, many traits were in grey literature or remained non-digitised, which rendered them inaccessible to the global scientific community. Addressing this gap, our Ukrainian Plant Trait Database (UkrTrait v. 1.0) represents a significant step forward. We compiled and digitised plant traits from local Ukrainian literature sources. Furthermore, we performed our own field and laboratory measurements of various plant traits that were not previously available in literature. In the current version of the UkrTrait, we focus on vascular plant species that are absent from the other European trait databases, with emphasis on species that are representative for the steppe vegetation. Traits assembled from literature include life span (annuals, biennials, perennials), plant height, flowering period (flowering months), life form (by Raunkiaer), plant growth form and others. Our own measured traits include seed mass, seed shape, leaf area, leaf nitrogen concentration and leaf phosphorus concentration. The current version, i.e. UkrTrait v. 1.0, comprises digitised literature data of 287,948 records of 75 traits for 6,198 taxa and our own trait measurements of 2,390 records of 12 traits for 388 taxa. [ABSTRACT FROM AUTHOR]

Responses of post-disposal germination to light play a crucial role in shaping germination niches and determining the success of seedling establishment, ultimately impacting species distribution and community composition. Seed traits are pivotal factors that influence species' germination, dispersal, and life history strategies. However, it remains unclear whether the relationship between seed traits and the light plasticity of germination is regulated by factors such as life history, photoblastic taxa, and dispersal ability.We measured the seed shape and seed mass of 114 species on the grasslands of the Tibetan Plateau. Germination experiments were conducted under two light conditions: dark and light. We also classified species based on photoblastic taxa (photostimulation vs. photoinhibition), life history (annual vs. perennial), and dispersal ability (weak vs. strong). Phylogenetic structural equation models (SEM) were used to test the complex relationship between seed traits, life history, dispersal ability, and light plasticity.We found that neither seed mass nor shape differed between the two photoblastic taxa. Species with photostimulation taxa exhibited a greater light plasticity of germination compared with photoinhibition taxa. Non-spherical seeds (elongated or flat) possessed low light plasticity of germination. The relationship between seed mass and germination light plasticity varied in different photoblastic taxa. Specifically, in photostimulation species, increased seed mass was associated with higher light plasticity of germination, whereas in photoinhibition species, an opposite relationship was evident. Moreover, dispersal ability and life history indirectly influenced the light plasticity of germination via seed shape.Our results imply that different combinations of seed traits can shape germination strategies in response to light stimulation, which in turn may influence the germination niches differentiation and species persistence in soil. Furthermore, life history and dispersal ability can indirectly affect the light plasticity of germination, which implies that the reproductive strategy of species to adapt to the environment may be regulated by multi-faceted life history strategies.

Summary: Information on seed persistence and seedling emergence from the soil seed bank is critical for understanding species coexistence and predicting community dynamics. However, quantifying seed persistence in the soil is challenging; thus, its association with other life‐history traits is poorly known on a broad scale.Using germination phenology for 349 species in a 42‐yr experiment, we quantified the persistence–emergence correlations and their associations with intrinsic regeneration traits using Bayesian phylogenetic multilevel models.We showed no trade‐off between seed persistence and seedling emergence. Physically dormant seeds were more persistent but exhibited lower emergence than nondormant seeds. Monocarpic species had both higher persistence and emergence than polycarpic species. Seed mass posed a marginal proxy for persistence, while emergence almost doubled from the smallest to the largest seeds.This study challenges the traditional assumption and is the first demonstration of noncorrelation between persistence and emergence, probably owing to the complexity of regenerative strategies. Species with short persistence and low emergence would be the most vulnerable for in situ conservation. Our analyses of this unique, long‐term dataset provide a strong incentive for further experimental studies and a rich data resource for future syntheses. See also the Commentary on this article by Meitzel, 241: 521–522. [ABSTRACT FROM AUTHOR]

Summary: Seed dispersal mechanisms play a crucial role in driving evolutionary changes in seed and fruit traits. While previous studies have primarily focussed on the mean or maximum values of these traits, there is also significant intraspecific variation in them. Therefore, it is pertinent to investigate whether dispersal mechanisms can explain intraspecific variations in these traits.Taking seed size as a case study, we compiled a global dataset comprising 3424 records of intraspecific variation in seed size (IVSS), belonging to 691 plant species and 131 families. We provided the first comprehensive quantification of dispersal mechanism effects on IVSS.Biotic‐dispersed species exhibited a larger IVSS than abiotic‐dispersed species. Synzoochory species had a larger IVSS than endozoochory, epizoochory, and myrmecochory species. Vertebrate‐dispersed species exhibited a larger IVSS than invertebrate‐dispersed species, and species dispersed by birds exhibited a larger IVSS than mammal‐dispersed species. Additionally, a clear negative correlation was detected between IVSS and disperser body mass.Our results prove that the IVSS is associated with the seed dispersal mechanism. This study advances our understanding of the dispersal mechanisms' crucial role in seed size evolution, encompassing not only the mean value but also the variation. [ABSTRACT FROM AUTHOR]

Characterising host selection mechanisms and the performance of seed‐predating insects on different hosts has broad implications for ecology and applied entomology.We assessed host selection and performance of endophagous seed‐predating insects on three species of Copaifera, testing two hypotheses: (i) large‐sized trees produce larger seeds and have higher levels of seed predation than their smaller congeneric relatives, and (ii) endophagous seed‐predating insects that develop in larger‐seeded trees exhibit higher body mass, lipid content, and muscle mass as they obtain higher amount of food resources.Unpredated seeds of the large‐sized Copaifera langsdorffii showed greater mass than their smaller congeneric relatives C. arenicola and C. oblongifolia.Two species of endophagous seed‐predating beetles (Rhinochenus brevicollis and Apion sp.) were found attacking seeds of the three Copaifera species. Rhinochenus brevicollis preyed on a higher percentage of seeds than Apion sp. The shrub C. oblongifolia had the highest percentage of seed predation, contradicting our original hypothesis that larger species have a higher percentage of seed predation.Rhinochenus brevicollis preyed on a higher percentage of seeds of larger‐sized species than Apion sp. The higher dispersal ability of R. brevicollis associated with different patterns of plant species distribution may be the mechanism driving differential seed predation among Copaifera species.Adult insects that emerged from C. langsdorffii seeds showed higher body mass and lipidic content. It is likely that insects developing in larger seeds obtain a higher amount of food resources during their development. Finally, we observed a positive relationship between body weight and lipidic content in adults of R. brevicollis. We suggest that studies shedding light onto insect performance in different host‐sized seeds are necessary to understand host selection by beetles. [ABSTRACT FROM AUTHOR]

Small isolated plant populations are one of the consequences of fragmentation of natural habitats by humans. We asked what effect does the creation of smaller populations from larger ones has on the plant fitness-related trait seed germination. Using information on 119 species (142 species entries) in 50 families, we found that seeds in only 35.2% of the species entries from larger populations germinated to higher percentages than those from smaller populations. In the other entries, seeds from large and small populations germinated equally well (57.7% of total entries) or seeds from small populations germinated better (7.0% of total entries) than those from large populations. These results indicate that population size is not a reliable predictor of seed germinability. Furthermore, there was little relationship between seed germination and either seed mass, genetic diversity or degree of population isolation, or between population size and genetic diversity. [ABSTRACT FROM AUTHOR]

Motivation: Due to language and networking barriers, global initiatives to compile trait data often fail to integrate data from sources in non‐English languages or scientists that largely speak and write in non‐English languages. To illustrate the potential for regional databases to fill gaps in trait data, and how such databases may fill critical gaps in global biodiversity databases, we built the Rasgos‐CL Database. Rasgos‐CL provides a comprehensive set of plant traits for the woody flora of Chile by mobilizing and standardizing unstructured data largely from the Spanish‐language literature. We quantified the gains in trait coverage compared to global trait databases and identified phylogenetic and geographic biases of trait data gaps. Main Types of Variables Contained: Rasgos‐CL contains 25,174 trait records, including 2 continuous and 21 categorical traits for 662 woody species. Spatial Location and Grain: National coverage, with species that occur across all ecosystems in continental Chile. Time Period and Grain: Data were extracted from sources published between 1833 and 2023. Major Taxa and Level of Measurement: Rasgos‐CL includes trait data aggregated at the species level for 662 tree and shrub species, and also provides trait records from individual data sources. Software Format: Rasgos‐CL includes four csv files. A GitHub repository contains the csv files. [ABSTRACT FROM AUTHOR]

Although variation in seed mass can be attributed to other plant functional traits such as plant height, leaf size, genome size, growth form, leaf N and phylogeny, until now, there has been little information on the relative contributions of these factors to variation in seed mass. We compiled data consisting of 1071 vascular plant species from the literature to quantify the relationships between seed mass, explanatory variables and phylogeny. Strong phylogenetic signals of these explanatory variables reflected inherited ancestral traits of the plant species. Without controlling phylogeny, growth form and leaf N are associated with seed mass. However, this association disappeared when accounting for phylogeny. Plant height, leaf area, and genome size showed consistent positive relationship with seed mass irrespective of phylogeny. Using phylogenetic partial R²s model, phylogeny explained 50.89% of the variance in seed mass, much more than plant height, leaf area, genome size, leaf N, and growth form explaining only 7.39%, 0.58%, 1.85%, 0.06% and 0.09%, respectively. Therefore, future ecological work investigating the evolution of seed size should be cautious given that phylogeny is the best overall predictor for seed mass. Our study provides a novel avenue for clarifying variation in functional traits across plant species, improving our better understanding of global patterns in plant traits. [ABSTRACT FROM AUTHOR]

Premise of research. Maternal environment can influence the seed ecophysiology, for example, of species that produce fruits in different seasons. Due to seasonal variations in environmental factors, differences in germination responses, seed traits, and seedling size may occur. Using seeds of Piper umbellatum produced in the same population in both the rainy and dry seasons, we evaluated the effects of temperature variations and water availability on germination parameters, root growth, and seed traits. Methodology. Eight temperature treatments (15°C, 20°C, 23°C, 25°C, 28°C, 30°C, 35°C, and alternation between 30°C and 20°C) and four water potentials (0, −0.3, −0.6, and −1.2 MPa) were performed. The following parameters were analyzed: germination onset, germination percentage (G%), mean germination time (MGT), root elongation, seed longevity during ex situ storage, and dry mass of seeds. Pivotal results. All parameters analyzed differed according to the seed production period. The rainy-season seeds had greater germinability and longevity, as they started to germinate first with higher G% and lower MGT values than the dry-season seeds, which were more sensitive to the effects of water deficit in relation to germination parameters. Dry-season seeds had higher dry mass, and their seedlings had greater root growth than those from rainy-season seeds. This balance between germination parameters and traits of seeds and seedlings reflects the existence of an intergenerational memory of stress. Conclusions. The maternal environment during the seed production period influenced germination responses, seed traits, and root growth. The first stages of plant development can be strongly impacted by climate change, and the responses to these changes can vary according to the period of seed production in the same species. [ABSTRACT FROM AUTHOR]

Seed germination and dispersal have an important impact on the establishment and spread of invasive plants. Understanding the extent of intraspecific seed trait variations can enhance our understanding of how invasive plants respond to environmental change after introduction and help predict the dynamic of invasive species under future environmental conditions. However, less attention has been given to the variation in seed traits within species as opposed to among species. We compared seed production, seed morphological traits, dispersal ability, and seedling performance of Chromolaena odorata from 10 introduced populations in Asia and 12 native populations in America in a common garden. The results showed that range (introduced vs. native) and climate affected these traits. Compared with the native population, the introduced populations had higher seed numbers per capitula, lighter seeds, and higher potential dispersal ability seeds (lower terminal velocity) but lower germination rates and seedling lengths. Climatic clines in seed numbers per capitula and pappus length were observed; however, the clines in pappus length differed between the introduced and native populations. Trait covariation patterns were also different between both ranges. In the native populations, there was a trade-off between seed numbers per capitula and seed mass, while this relationship was not found for the introduced populations. These results indicate that C. odorata alters the ecological strategy of seed following invasion, which facilitates its establishment and fast dispersal and contributes to successful invasion in the introduced ranges.

Frequency-dependent predation is common in predator–prey interactions. Size is an important characteristic of seeds and is crucial in the regeneration stage of plant seeds. However, the frequency dependence of animal predation on seed size has not been reported. In this study, we conducted a field experiment and used different sizes of Liaodong oak (Quercus wutaishanica) seeds to test the frequency dependence of intraspecific seed size selection in rodents. We used the number ratio of large to small seeds as the frequency. The results show that the rate of small seeds being eaten in situ was significantly higher than that of large seeds (p < 0.05). The rates of different-sized seeds being eaten after removal decreased with increasing frequencies, and there was no significant difference between frequencies except for 1:9 and 9:1. The rates of large seeds being scatter-hoarded were significantly higher than those of small seeds at different frequencies (p < 0.05). The eating distances after removal of large seeds were significantly longer than those of small seeds at the same frequencies (p < 0.05). Furthermore, the scatter-hoarding distances of large seeds were significantly longer than those of small seeds at three frequencies (1:9, 3:7, and 9:1) (p < 0.05). That is, rodents consumed more small seeds in situ, dispersed and scatter-hoarded more large seeds, and dispersed large seeds over longer distances. Rodents exhibited a negative frequency dependence for small seeds and a positive frequency dependence for large seeds on being eaten in situ. Moreover, rodents exhibited a negative frequency dependence for large seeds and a positive frequency dependence for small seeds on being eaten after removal and scatter-hoarding. These results reveal the frequency dependence of rodent selection on seed size and provide new insights into animal-mediated seed dispersal and the regeneration of plant populations.

Spatiotemporal variation of seed rain reflects the response of plants in terms of their reproductive strategy to environmental gradients. In this study, we collected seeds from four sites in the Dalaoling Nature Reserve, Hubei Province, China, between 2011 and 2014, measured seed output and seed mass as seed rain traits, and compared their interannual and elevational variation. Then, we ran phylogenetic generalized mixed linear models (PGLMMs) to explore the effects of temperature and precipitation as well as interspecific differences on seed rain, and fitted the best regression models for seed rain vs. weather of canopy and understory species. The results showed no correlation between values of seed output and seed mass. However, the variation of the two traits showed significantly positive correlation. Seed output of canopy species generally decreased with increasing elevation, and showed significant interannual difference; however, seed output of understory species and seed mass for both canopy and understory species did not show consistency tends along elevational or in interannual variation. Seed output was significantly affected by temperature and precipitation, while seed mass mainly varied due to interspecific differences. Weather explained more the variation of the seed output of canopy species than that of understory species, with R2 values of 43.0% and 29.9%, respectively. These results suggested that canopy plants contributed more to the reproductive dynamics of the whole communities, and the canopy's buffer effect on the underground weakened the response of understory plants to weather variation in terms of their reproductive strategy.

Plant functional trait frameworks have been increasingly used to understand plant community dynamics, linkages between plants and ecosystem function, and have recently been applied to inform species selection for restoration of many ecosystem types. Yet, despite rapid development in this field over the past decade, the use of plant functional trait frameworks in the context of wetland restoration remains limited. Ambitious wetland restoration goals, and previous difficulties to meet them, underscore the need for continued refinement of science-backed restoration approaches for present and future conditions. Plant functional traits are one approach that deserves additional attention and scientific inquiry to inform restoration in wetlands. We conducted a systematic review of the peer-reviewed literature (published 2000 to 2020) addressing plant functional traits in wetland restoration. Here, we summarize that body of literature and identify factors limiting the inclusion of plant functional trait frameworks in wetland restoration. We emphasize the need for consensus on terminology and trait selection in this field, provide definitive guidelines for moving this field forward for both researchers and practitioners, identify key plant functional traits to inform specific restoration goals, and highlight case studies exemplary of this approach in wetland restoration. A plant functional trait framework has the potential to inform and improve restoration of the world’s wetlands by making important linkages between traits, desired ecosystem functions, and restoration trajectories. However, the use of this approach requires further development and that both research and practice reach a consensus on which traits are most critical to measure. [ABSTRACT FROM AUTHOR]

Context. Australia's tropical montane cloud forests (TMCF) exhibit exceptional species richness and endemism. Determinants of regeneration via seed of these species are next to unknown, limiting our ability to quantify and project their vulnerability to climate change. The ratio of red to far-red light (R:FR) has been shown to influence seed germination of many tropical species. Aims. We investigated germination of six previously unstudied TMCF species in relation to the presence or absence of light (light/dark) and light quality (R:FR). We hypothesised that increased R:FR would lead to increased germination and that small-seeded species would be more likely to have a light requirement and be less sensitive to R:FR compared to larger-seeded species. Methods. Sunlight and polyester filters were used to create a gradient of R:FR ranging from0.1 to 1.14. Seeds were also sown in constant darkness. Key results. Across species we saw varying germination responses. Three of the four smallest-seeded species exhibited an absolute light requirement for germination and did not discriminate between different R:FR. Germination of the small-seeded TMCF endemic Dracophyllum increased exponentially with increasing R:FR. Germination of the largest-seeded species was inhibited by both low and high R:FR, and germination was higher in constant darkness than diurnal light/dark. All six species were able to germinate at remarkably low R:FR values. Conclusions. Light affects seed germination of Australia's TMCF plant species in a variety of ways. Implications. The findings of this study provide insights into plant recruitment in situ, and the acclimation potential of these species under reduced R:FR predicted for the future. [ABSTRACT FROM AUTHOR]

Seed-transfer zones attempt to match seed source and habitat, but the extent of environmental variation within climate-based zones can be substantial and potentially relevant to seed-transfer guidelines. We surveyed abiotic and biotic soil properties across elevation and insolation (amount of solar radiation) gradients within a 5 km2 (1.9 mi2) area in Montana and assessed relationships with plant traits in 5 native species. We detected substantial variation in soil physical, chemical, and biological properties along gradients. Differences in insolation due to topographical features predicted variation in soil moisture and maximum temperature, organic matter content, and magnesium, whereas elevation predicted minimum soil temperature and relative abundance of arbuscular mycorrhizal fungi. Elevation and insolation combined predicted plant productivity, soil potassium, calcium, sulfate, and iron concentrations. Yet, neither elevation nor insolation consistently correlated with variation in plant traits across species, potentially because of insufficient selection pressure or widespread seed dispersal throughout the area. Nonetheless, specific leaf area and seed weight, both heritable traits, correlated with changes in elevation and insolation in some species. Whether this variation is attributable to local adaptation or plasticity requires reciprocal transplant experiments and longer-term monitoring of the survival and fitness of plants. We show that elevation and insolation gradients can be effective predictors of some aspects of the soil environment. Systematically collecting seeds along elevation and insolation gradients can provide a breadth of plant traits to test trait-by-environment interactions in reciprocal transplant studies and reveal if matching heritable traits to environments within a climatic seed zone is beneficial. [ABSTRACT FROM AUTHOR]

Chromosome count, plant height, number of inflorescences per plant, number of seeds per inflorescence, seed weight, germination, and germination energy of plant seeds growing at altitudes of 200, 600, 1300, 2050, 2700, and 3050 m above sea level (Central Caucasus) were studied. The studies were conducted in 2013, 2014, and 2018 at the same sampling points. Chromosome counts were determined by the cytogenetic method. In the T. officinale species, highly polyploid specimens predominate in populations when invading anthropogenically disturbed territories of the highlands. Polyploid plants are larger in size compared to their low ploidy predecessors, but in high-altitude, selection is aimed at preserving smaller phenotypes. The increase in seed mass characteristic of polyploid plants was supported by natural selection and in conditions of highlands. Germination and germination energy did not change with the increase in altitude. [ABSTRACT FROM AUTHOR]

Beyond the study of the mean, functional ecology lacks a concise characterization of trait variance patterns across spatiotemporal scales. Traits are measured in different ways, using different metrics, and at different spatial (and rarely temporal) scales. This study expands on previous research by applying a ubiquitous and widely used empirical model—Taylor's Power Law—to functional trait variance with the goal of identifying general patterns of trait variance scaling (the behavior of trait variance across scales). We compiled data on tree seedling communities monitored over 10 years across 213 2 m2 plots and functional trait data from a subtropical forest in Puerto Rico. We examined trait‐based Taylor's Power Law at nested spatial and temporal scales. The scaling of variance with the mean was idiosyncratic across traits suggesting that the drivers of variation are likely to differ across traits that may make variance scaling theory elusive. However, slopes varied more in space than through time, suggesting that spatial environmental variability may have a larger role in driving trait variance than temporal variability. Empirical models that characterize taxonomic patterns across spatiotemporal scales, like Taylor's Power Law, can provide an insight into the scaling of functional traits, a necessary next step toward a more predictive trait‐based ecology. [ABSTRACT FROM AUTHOR]

Animal-mediated seed dispersal is very important for plant population regeneration and the stability of forest ecosystems. Seed size and cache density are important factors for seed dispersal, but we still know little about seed size selection at different cache densities. Here, we conducted field experiments in a Larix principis-rupprechtii plantation in the Liupan Mountains in Ningxia province to investigate the effects of tag-marked Quercus wutaishanica seeds of different sizes and cache densities on predation and the scatter-hoarding behavior of rodents. The results showed lower proportions of intact in situ (IIS) and eaten in situ (EIS) large seeds than small seeds at all levels of cache density, with the exception of IIS seeds at a 6.25 seed·m−2 cache density. A higher proportion of small seeds were eaten after removal (EAR), but a higher proportion of large seeds were scatter-hoarded (SH) by rodents at most cache densities. Furthermore, rodents preferentially removed large seeds farther away for eating or scatter-hoarding. The IIS and EIS proportions of both large and small seeds declined, but the proportion of the two types of seeds that were EAR fluctuated, increasing with increasing cache density. Rodents preferred to increase the proportion of scatter-hoarding of large seeds with increasing cache density, whereas the proportion of scatter-hoarding of small seeds was maximized at a cache density of 6.25 seed·m−2. Both the eaten distance after removal (EDAR) and scatter-hoarded distance (SHD) increased with increasing cache density. These results suggest that large seeds are more likely to be scatter-hoarded and removed to longer distances than small ones. Rodents tended to reduce the seed proportion of EIS seeds and increased the proportion of seeds EAR and SH, and accordingly increased EDAR and SHD with increasing cache density. This study provides some scientific basis for animal-mediated seed dispersal.

Germination is considered one of the most important stages influenced by environmental factors, with timing and abundance determining plant establishment and recruitment. However, seed germination traits in alpine/subalpine grasslands are poorly understood, despite alpine/subalpine plant populations are vulnerable to climate warming. In order to investigate seed germination response to diurnally alternating temperature (ΔT) and figure out the response differentiation between alpine and subalpine meadow plant populations, we sampled seeds from 140 populations representing 70 species across an elevation gradient on the eastern edge of the Tibetan Plateau. Seeds were exposed to two ΔT treatments to estimate the germination-related traits. Our results showed that germination characteristics in alpine/subalpine meadow populations were closely linked to ΔT. Under higher ΔT, both subalpine and alpine meadow plants exhibited longer MTG (mean germination time) and lower SYN (germination synchrony). The MTG of subalpine and alpine meadow populations were significantly prolonged by 1.40 d and 0.78 d, respectively, and the SYN were reduced by 0.07 and 0.04 respectively, under higher ΔT. The GNP (germination percentage) and UNC (germination uncertainty) of subalpine meadow plants also had significant differences between the two temperature treatments, indicated that subalpine meadow plants were more sensitive to ΔT changes. Furthermore, under higher and lower ΔT treatments, mean MTG of alpine plants was prolonged by 1.010 d and 1.397 d for each 1 mg increase in seed mass, respectively, and the mean SYN decreased by 0.017 and 0.019 for every 1 mg increase in seed mass, respectively. However, subalpine meadow plants only showed a positive correlation between UNC and seed mass, and a negative correlation between SYN and seed mass at higher ΔT when controlling for the effects of phylogeny, life history and plant size. Our results also suggest that rapid synchronous germination and delayed asynchronous germination coexist in taxa.

Plant-plant interactions are integral to the establishment and persistence of diversity in plant communities. For annual plant species that depend on seeds to regenerate, seed characteristics that confer fitness advantages may mediate processes such as plant-plant interactions. Seed mass is known to vary widely and has been shown to associate with species' differences in stress tolerance and competitive effects. However, understanding of how seed mass influences species' responses to competition is less well understood. Using natural assemblages of six closely related annual plant species in Western Australia, we implemented a thinning study to assess how seed mass influences the outcomes of plant-plant interactions. We found relatively weak evidence for competition or facilitation among species. Our strongest results indicated that heavy-seeded species had lower survivorship than light-seeded species when interacting with heterospecifics. Seed mass was also negatively related to overall survival, counter to expectations. These findings indicate some evidence for trade-offs mediated by seed mass in this system. However, we acknowledge that other factors may have influenced our results, such as the use of natural assemblages (rather than using sowing experiments) and the presence of important small-scale environmental variation not captured with our choice of abiotic variables. Further research is required to clarify the role of seed mass in this diverse annual system, ideally including many focal species, and using sowing experiments. [ABSTRACT FROM AUTHOR]

Ecological processes such as seed dispersal or plant–plant interactions and environmental constraints such as climate or soil heterogeneity are known to influence establishment, and thus the spatial patterns of plant communities and populations. In this study, we hypothesized that key functional traits such as the specific leaf area (SLA), reproductive ratio (reproductive/vegetative biomass), seed mass and maximum plant height would influence the spatial patterns of individual species in annual, gypsophilous plant communities, and that these effects would be modulated by both the soil surface structure (biocrust) and climate (precipitation) conditions.We mapped the spatial patterns of all plants found in six 1 × 1 m plots (more than 1000 individuals per plot) in both the seedling (autumn) and adult stages (spring) under two biocrust experimental conditions (intact vs. disturbed biocrust) during two consecutive years which were contrasted in term of precipitation (dry year and wet year). To assess the spatial patterns of seedlings and adults, we fitted four different spatial point pattern models (i.e. Poisson, inhomogeneous Poisson, Poisson cluster and inhomogeneous Poisson cluster processes) to each of the 242 populations of the 26 most abundant species that had more than 15 individuals per plot.Most seedling populations exhibited clustered spatial patterns that persisted in the adult stage, which suggests that short‐distance dispersal is an adaptive trait for soil specialists such as gypsophilous plants. One‐third of the populations fitted an inhomogeneous model best but the physical structure of the biocrust was not related to them. More importantly, we found a connection between the functional strategies of species and the spatial distribution of plants. In particular, during the dry year, irrespective of the biocrust conditions, species with a high SLA and high Rep/Veg mainly exhibited clustered spatial patterns, whereas low SLA and low Rep/Veg were associated with random distributions. Species with heavy and light seed masses had random and clustered patterns, respectively. In both the dry and wet years, species with lower maximum heights had clustered patterns, whereas taller species exhibited random patterns. In addition, species with heavier seeds and greater maximum heights had the largest cluster sizes.Our results confirm that the spatial patterns of seedlings and adult plants are significantly determined by the functional strategy of each species. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The invasion of annual grasses into historically perennial-dominated systems is a global biodiversity threat. While significant, it is not known how evolutionary changes in functional traits during the invasion process may contribute to invader success. We examined how functional traits of a widely distributed invasive annual grass medusahead (Taeniatherum caput-medusae (L.) Nevski) differed across native-range and invaded-range populations and compared these trait values to those of a common native perennial, squirreltail (Elymus elymoides (Raf.) Swezey). In greenhouse and growth chamber studies we screened a range of plant, seed and seedling functional traits and determined how variation in these traits contributed to variation in plant biomass. Our results show medusahead maintains a higher relative growth rate (RGR) than squirreltail, but the mechanism differed depending on origin with native-range medusahead achieving a higher RGR through a higher specific leaf area and the invaded-range medusahead achieving a higher RGR though a higher net assimilation rate. Contrary to previous literature, we did not find that medusahead evolved traits allowing larger biomass in its invaded range. Instead, native-range medusahead populations grew bigger than invaded-range populations, primarily due to differences in seed size. While counter to expectations, smaller seed mass may provide invaded-range medusahead populations an advantage in terms of dispersal and higher seed bank density compared to native-range populations. Thus, life history differences, altered disturbance regimes, and a shift towards production of smaller but a greater number of seeds may act, in combination, to facilitate invasion of annual grasses into perennial dominated systems. [ABSTRACT FROM AUTHOR]

Seeds may differ in terms of dormancy, longevity, sensitivity to desiccation and dry mass, according to the timing (dry season/rainy season) of diaspore dispersal. In addition, seasonal variations in temperature and water availability can act as signals of the season during seed development, influencing germination responses and root growth. We evaluated the effects of temperature variations and water availability on germination parameters, root growth and seed traits of four coexisting Piper species in seasonal vegetation that differed in diaspore dispersal timing.Eight temperature treatments (15, 20, 23, 25, 28, 30, 35 °C, and alternate 30 °C–20 °C) and four induced water potentials (0, −0.3, −0.6 and −1.2 MPa) were used. The parameters germination onset, germination percentage (G%), mean germination time (MGT), root elongation, seed longevity during ex situ storage and dry mass of seeds were evaluated.Germination responses observed were independent of the diaspore dispersal timing, such as variations in germination onset, G% and MGT, both in temperature and water availability treatments. In contrast, root elongation, longevity and dry mass of seeds varied according to the time of diaspore dispersal.Our results corroborate the hypothesis that the timing of diaspore dispersal is an important factor in controlling the initial development of seedlings in seasonal vegetation, but not in germination responses. The predominance of negative effects of temperature increases and water deficit on root growth shows that the initial stages of plant development can be strongly impacted by these environmental factors. [ABSTRACT FROM AUTHOR]

Alterations in global climate via extreme precipitation will have broadscale implications on ecosystem functioning. The increased frequency of drought, coupled with heavy, episodic rainfall are likely to generate impacts on biotic and abiotic processes across aquatic and terrestrial ecosystems. Despite the demonstrated shifts in global precipitation, less is known how extreme precipitation interacts with biophysical factors to control future demographic processes, especially those sensitive to climate extremes such as organismal recruitment and survival. We utilized a field‐based precipitation manipulation experiment in 0.1 ha forest canopy openings to test future climate scenarios characterized by extreme precipitation on temperate tree seedling survival. The effects of planting seedbeds (undisturbed leaf litter/organic material vs. scarified, exposed mineral soils), seedling ontogeny, species, and functional traits were examined against four statistically defined precipitation scenarios. Results indicated that seedlings grown within precipitation treatments characterized by heavy, episodic rainfall preceded by prolonged drying responded similarly to drought treatments lacking episodic inputs. Moreover, among all treatment conditions tested, scarified seedbeds most strongly affected seedling survivorship (odds ratio 6.9). Compared with any precipitation treatment, the effect size (predicted probabilities) of the seedbed was more than twice as important in controlling seedling survivorship. However, the interaction between precipitation and seedbed resulted in a 27.9% improvement in survivorship for moisture‐sensitive species. Seedling sensitivity to moisture was variable among species, and most closely linked with functional traits such as seed mass. For instance, under dry moisture regimes, survivorship increased linearly with seed mass (log transformed; adjusted R2 = 0.72, p < 0.001), yet no relationship was apparent under wet moisture regimes. Although precipitation influenced survival, extreme rainfall events were not enough to offset moisture deficits nor provide a rescue effect under drought conditions. The relationships reported here highlight the importance of plant seedbeds and species (e.g., functional traits) as edaphic and biotic controls that modify the influence of extreme future precipitation on seedling survival in temperate forests. Finally, we demonstrated the biophysical factors that were most influential to early forest development and that may override the negative effects of increasingly variable precipitation. This work contributes to refinements of species distribution models and can inform reforestation strategies intended to maintain biodiversity and ecosystem function under increasing climate extremes. [ABSTRACT FROM AUTHOR]

In the context of climate change in recent years, the fate of woody plant seed has an important impact on forest regeneration. Seed mass is an important reproductive strategy of plants. There are huge differences between gymnosperms (mainly conifers) and angiosperms (flowering plants) in terms of reproduction and hydraulic strategies; however, little is known about changes in seed mass along climate aridity gradients between taxonomical groups such as gymnosperms and angiosperms, which limit our understanding on the fate of woody plants under warming-induced climate drying. We collected seed mass data from a total of 2575 woody plant individuals, including 145 species of gymnosperms and 1487 species of angiosperms, across different climatic zones in China. We mapped the distribution pattern of gymnosperm and angiosperm seed mass in China, with angiosperms being maximal near the 400 mm iso-precipitation line. Our phylogenetic analysis results show that seed mass exhibited significant phylogenic signals (p < 0.001) and was also strongly influenced by functional traits (growth type, fruit type, and dispersal mode). The results of linear regression and hierarchical partitioning analysis showed a stronger correlation between gymnosperm seed mass and environmental factors, and a higher independent aridity index effect on gymnosperm seed mass than angiosperm seed mass. The different patterns of seed mass along a climate aridity gradient between gymnosperms and angiosperms may point to different future fates for these two taxonomic groups, while the higher sensitivity of gymnosperm seed mass to environmental conditions may reduce their reproductive rate under the background of climate warming and drying. [ABSTRACT FROM AUTHOR]

Some research indicates that soil seed banks can promote species coexistence through storage effects. However, the seed bank mechanism that maintains plant assembly and its role in degraded grassland restoration are still not clear. We collected seed bank samples from early, mid and late secondary successional stages of an abandoned subalpine meadow on the Tibetan Plateau, and samples from each stage were exposed to full (i.e., natural), mid, and low light treatments in the field to represent light availability at the bottom/understory (soil surface) of a plant community in the early, mid and late stages of succession, respectively. Species richness, seed density, species composition, and community weighted mean values (CWMs) of seed mass of the species whose seeds germinated in soil samples were evaluated. In response to the light treatments, species richness increased significantly with increased light only for the late successional stage, seed density increased significantly with increased light only in the early and mid successional stages, and seed mass decreased significantly with increased light only in the mid and late successional stages. Species composition differed significantly among the light treatments only in the late successional stage. For the successional series, species richness and seed mass of the species that germinated increased significantly with succession only under mid and full light treatments. Seed density decreased significantly with succession in each light treatment. Species composition differed significantly between the early‐ and late stage and between the mid and late stage in each light treatment. Both the abiotic (light) and biotic (seed mass) factors influence seed bank recruitment to the plant community. Regeneration of small‐seeded species in the seed bank was inhibited under low light in the late successional stage. The balance of stochastic and deterministic processes along a successional gradient was determined by regeneration from the seed bank depending on light intensity change. Differences in seed response to light intensity change largely determined plant community assembly. Our findings should help in the development of effective conservation and restoration strategies. [ABSTRACT FROM AUTHOR]

Most terrestrial plants disperse by seeds, yet the relationship between seed mass, seed dispersal traits, and plant dispersion is poorly understood. We quantified seed traits for 48 species of native and introduced plants from the grasslands of western Montana, USA, to investigate the relationships between seed traits and plant dispersion patterns. Additionally, because the linkage between dispersal traits and dispersion patterns might be stronger for actively dispersing species, we compared these patterns between native and introduced plants. Finally, we evaluated the efficacy of trait databases versus locally collected data for examining these questions. We found that seed mass correlated positively with the presence of dispersal adaptations such as pappi and awns, but only for introduced plants, for which larger-seeded species were four times as likely to exhibit dispersal adaptations as smaller-seeded species. This finding suggests that introduced plants with larger seeds may require dispersal adaptations to overcome seed mass limitations and invasion barriers. Notably, larger-seeded exotics also tended to be more widely distributed than their smaller-seeded counterparts, again a pattern that was not apparent for native taxa. These results suggest that the effects of seed traits on plant distribution patterns for expanding populations may be obscured for long-established species by other ecological filters (e.g., competition). Finally, seed masses from databases differed from locally collected data for 77% of the study species. Yet, database seed masses correlated with local estimates and generated similar results. Nonetheless, average seed masses differed up to 500-fold between data sources, suggesting that local data provides more valid results for community-level questions. [ABSTRACT FROM AUTHOR]

Plants vary in their reproductive allocation to embryo provisioning and seed dispersal. This may be mediated by genetic and/or environmental factors, resulting in varying seed properties among populations and years but few studies have explored this for invasive plants. Chinese Tallow Tree (Triadica sebifera) is a problematic invasive species in the southeastern United States. Its seeds are dispersed by birds that digest the waxy coating and excrete the seed. Here, we determined seed (resources for embryo) and wax mass (reward for disperser) for individual trees from 22 populations along a gradient from Texas to North Carolina over ~ 20 years. We used historical temperature, precipitation, and drought data to explore environmental effects on fruit provisioning. Seed sizes varied little for an individual tree in a given year. Wax mass of populations in locations with wet fall weather on average had greater absolute and relative wax mass. Seed mass was higher in years with wet spring weather and lower with more severe drought in the fall. Wax mass was higher in years with warm, dry winters. This suggests that environmental effects on fruit provisioning of this invasive tree vary by season with allocation to embryo resources sensitive to moisture during early and late fruit development and allocation to dispersal depending more on weather during dormancy. [ABSTRACT FROM AUTHOR]

The establishment of native trees in exotic forest plantations can improve economic and ecological outcomes, and functional traits can help understanding differential responses of growth rates to stand variables. It is well known that growth rates can depend on functional traits and that the associations between functional traits and plant growth vary across ontogenetic stages. Here we studied if the response of growth rate to stand variables, that reflect ecological conditions, is associated with wood density, seed mass and height at maturity and if such relationships differ between saplings and seedlings. We measured the stem diameter increment over two years in 164 seedlings and 290 saplings of 30 tree species in 9 loblolly pine plantations in the Atlantic Forest, Argentina. The relationship between stem diameter increment and stand basal area, mean canopy openness and stand age was evaluated. The growth rate of saplings decreased with basal area and increased with canopy openness in species with wood density < 0.56 g.cm-3 or height at maturity > 23 m. No differences in growth rate response were found along seed mass. No consistent relationships between growth rate and stand variables were found in seedlings. We concluded that seedling growth rate is unrelated to stand variables while responsive species at sapling stage are those with low wood density or medium-high height at maturity. Silvicultural treatments reducing basal area can benefit the planted trees as well as unplanted saplings of medium-high valued native trees. [ABSTRACT FROM AUTHOR]

Seed regeneration is a critical stage in the life histories of plants, affecting species' abilities to maintain local populations, evolve, and disperse to new sites. In this study, we test for local adaptations to drought in germination and seedling growth of two alpine forbs with contrasting habitat preferences: the alpine generalist Veronica alpina and the snowbed specialist Sibbaldia procumbens. We sampled seeds of each species from four populations spanning a precipitation gradient from 1200 to 3400 mm/year in western Norway. In a growth chamber experiment, we germinated seeds from each population at 10 different water potentials under controlled light and temperature conditions. Drought led to lower germination percentage in both species, and additionally, slower germination, and more investment in roots for V. alpina. These responses varied along the precipitation gradient. Seeds from the driest populations had higher germination percentage, shorter time to germination, and higher investments in the roots under drought conditions than the seeds from the wettest populations – suggesting local adaption to drought. The snowbed specialist, S. procumbens, had lower germination percentages under drought, but otherwise did not respond to drought in ways that indicate physiological or morphological adaptions to drought. S. procumbens germination also did not vary systematically with precipitation of the source site, but heavier‐seeded populations germinated to higher rates and tolerated drought better. Our study is the first to test drought effects on seed regeneration in alpine plants populations from high‐precipitation regions. We found evidence that germination and seedling traits may show adaptation to drought even in populations from wet habitats. Our results also indicate that alpine generalists might be more adapted to drought and show more local adaptations in drought responses than snowbed specialists. [ABSTRACT FROM AUTHOR]

Questions: All else being equal, populations of dioecious species with a 50:50 sex ratio have only half the effective reproductive population size of bisexual species of equal abundance. Consequently, there is a need to explain how dioecious and bisexual species coexist. Increased mean individual seed mass, fecundity, and population density have all been proposed as attributes of unisexual individuals or populations that may contribute to the persistence or resilience of dioecious species. To date, no studies have compared sympatric dioecious and cosexual species with respect to all three components of fitness. In this study, we sought evidence for these compensatory advantages (higher seed mass, greater seed production per unit basal area, and higher population density) in dioecious species. Location: Five 20–25 ha forest dynamic plots spanning a latitudinal gradient in China, including two temperate, two subtropical, and one tropical forest. Methods: We used a phylogenetically corrected generalized linear modelling approach to assess the phylogenetic dependence and joint evolution of sexual system, seed mass and production, and ecological abundances among 48–333 species and 32,568–136,237 individuals per forest. Results: Across all five forests, we detected no consistent advantage for dioecious relative to sympatric cosexual species with respect to mean individual seed mass, seed production or the density of stems in any size class. Conclusions: Our study suggests that seed traits may provide compensatory mechanisms in some forests, but most often the coexistence of sexual systems cannot be explained by advantages of dioecy related to seed quality and demographic parameters. Future investigations of the factors that promote coexistence may increase our understanding by expanding the search to include attributes such as lifespan and tolerance or resistance to herbivores.

Abstract Seed regeneration is a critical stage in the life histories of plants, affecting species' abilities to maintain local populations, evolve, and disperse to new sites. In this study, we test for local adaptations to drought in germination and seedling growth of two alpine forbs with contrasting habitat preferences: the alpine generalist Veronica alpina and the snowbed specialist Sibbaldia procumbens. We sampled seeds of each species from four populations spanning a precipitation gradient from 1200 to 3400 mm/year in western Norway. In a growth chamber experiment, we germinated seeds from each population at 10 different water potentials under controlled light and temperature conditions. Drought led to lower germination percentage in both species, and additionally, slower germination, and more investment in roots for V. alpina. These responses varied along the precipitation gradient. Seeds from the driest populations had higher germination percentage, shorter time to germination, and higher investments in the roots under drought conditions than the seeds from the wettest populations – suggesting local adaption to drought. The snowbed specialist, S. procumbens, had lower germination percentages under drought, but otherwise did not respond to drought in ways that indicate physiological or morphological adaptions to drought. S. procumbens germination also did not vary systematically with precipitation of the source site, but heavier‐seeded populations germinated to higher rates and tolerated drought better. Our study is the first to test drought effects on seed regeneration in alpine plants populations from high‐precipitation regions. We found evidence that germination and seedling traits may show adaptation to drought even in populations from wet habitats. Our results also indicate that alpine generalists might be more adapted to drought and show more local adaptations in drought responses than snowbed specialists.

Advancing functional ecology depends fundamentally on the availability of data on reproductive traits, including those from tropical plants, which have been historically underrepresented in global trait databases. Although some valuable databases have been created recently, they are mainly restricted to temperate areas and vegetative traits such as leaf and wood traits. Here, we present Rock n' Seeds, a database of seed functional traits and germination experiments from Brazilian rock outcrop vegetation, recognized as outstanding centers of diversity and endemism. Data were compiled through a systematic literature search, resulting in 103 publications from which seed functional traits were extracted. The database includes information on 16 functional traits for 383 taxa from 148 genera, 50 families, and 25 orders. These 16 traits include two dispersal, six production, four morphological, two biophysical, and two germination traits—the major axes of the seed ecological spectrum. The database also provides raw data for 48 germination experiments, for a total of 10,187 records for 281 taxa. Germination experiments in the database assessed the effect of a wide range of abiotic and biotic factors on germination and different dormancy‐breaking treatments. Notably, 8255 of these records include daily germination counts. This input will facilitate synthesizing germination data and using this database for a myriad of ecological questions. Given the variety of seed traits and the extensive germination information made available by this database, we expect it to be a valuable resource advancing comparative functional ecology and guiding seed‐based restoration and biodiversity conservation in tropical megadiverse ecosystems. There are no copyright restrictions on the data; please cite this paper when using the current data in publications; also the authors would appreciate notification of how the data are used in publications. [ABSTRACT FROM AUTHOR]