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Seed Bank (seed + bank)

Distribution by Scientific Domains
Life Sciences63%
Earth and Environmental Science33%
Distribution within Life Sciences
Ecology & Organismal Biology46%
Plant Science7%

Kinds of Seed Bank

  • persistent seed bank
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  • persistent soil seed bank
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  • soil seed bank
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    Terms modified by Seed Bank

  • seed bank composition
  • seed bank density
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  • seed bank dynamics
  • seed bank persistence
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    Selected Abstracts

    Seed Dynamics in Relation to Gaps in a Tropical Montane Rainforest of Hainan Island, South China: (II) Seed Bank

    JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2008
    Run-Guo Zang
    Abstract Spatial and temporal patterns of seed bank dynamics in relation to gaps in an old growth tropical montane rainforest of Hainan Island, South China, were studied over two consecutive years. From June 2001 to June 2003, soil seed bank sampling blocks were taken near each of the four sides of each seed trap and immediately put into a nursery for observation of seedling emergence dynamics in four seasons (each experiment in each season). The abundances of seedlings that emerged from seed banks showed the trend of vine functional group (VFG) > shrub functional group (SFG) > tree functional group (TFG) > herb functional group (HFG), but the trend in species richness of seedlings that emerged from the soil seed banks was TFG > VFG > SFG > HFG. The abundances of seedlings that emerged from seed banks in the three gap zones showed no significant differences, but significant differences did exist for the species richness. The time of sampling or seasons of experiments had significant influences on both the species richness and seedling abundances. The seedling emergence processes of each experiment all revealed the unimodal patterns. Few emergences occurred 1 year after each experiment. Compared with those under closed canopies, the recruitment rates from seed to seedlings and from seedlings to saplings in gaps were higher, but the mortality rates from saplings to big trees were also higher in the gaps. [source]

    Disturbance Effects on the Seed Bank of Mexican Cloud Forest Fragments,

    BIOTROPICA, Issue 3 2005
    C. Alvarez-Aquino
    ABSTRACT The density and floristic composition of the soil seed bank was assessed in six cloud forest fragments with different levels of human disturbance in central Veracruz, Mexico. A total of 8416 seeds germinated in 60 soil samples, at 5-cm depth, corresponding to 107 species, 85 genera, and 48 families. Significant differences were found among study sites in seed densities with values ranging from 873 to 3632/m2. Tree species contributed 20 percent of the total soil seed bank in four sites and herbs accounted for the majority of the species in each site. Among tree species, Trema micrantha displayed the highest seed density, accounting for 84 percent of the germinated seeds. In general, the tree species composition of the soil seed bank did not closely reflect the composition of the tree community. Results suggest that disturbance produced by human activities (trail use, selective cutting of trees, livestock) may influence the size and composition of the soil seed bank in forest fragments. Sites where human activity has been reduced showed the highest proportion of dormant seeds. RESUMEN La densidad y composición florística del banco de semillas del suelo se determinó en seis fragmentos de bosque de niebla con distinto nivel de alteración humana, en Veracruz, México. Un total de 8416 semillas germinaron en 60 muestras de suelo, correspondientes a 107 especies, 85 géneros y 48 familias. Se encontraron diferencias significativas entre los sitios de estudio, con valores desde 873 a 3632 semillas/m2. La mayoria de las especies fueron hierbas y en cuatro de los sitios las especies arbóreas contribuyeron un 20 por ciento al total de semillas del banco del suelo. Entre las especies arbóreas, Trema micrantha (L.) Blume (Ulmaceae) presentó la mayor densidad de semillas (84% de las semillas germinadas). En general, la composición de especies arbóreas en el banco del suelo no reflejó la composición de la comunidad de árboles en cada sitio. Los resultados sugieren que la alteración causada por actividad humana (uso de senderos, tala selectiva y pastoreo) puede influir en el tamaño y composición del banco de semillas del suelo en fragmentos de bosque. Los sitios donde la actividad humana es reducida tienen la mayor proporción de semillas latentes. [source]

    The Role of Soil Seed Banks in the Rehabilitation of Degraded Hillslopes in Southern Wello, Ethiopia,

    BIOTROPICA, Issue 1 2000
    Kebrom Tekle
    ABSTRACT The species composition in the soil seed bank of degraded hillslopes in southern Wello, Ethiopia, was assessed using the seedling emergence method and compared with that of the standing vegetation. Surface soils were sampled at 0-to 5-cm depth from 49 plots of four physiognomic vegetation classes (hereafter vegetation classes): forests, shrublands, grasslands, and degraded sites. Soils were spread on sterile sand in a glasshouse and watered. Emerging seedlings were recorded for five months until no new seedlings emerged. A total of 3969 seedlings belonging to 71 species and 30 families germinated. The species composition of the seed bank was dominated by 53 herb species (75%) compared to 2 tree species which accounted for only 3 percent of the total number of species. Seedling density differed significantly among vegetation classes and ranged from 391 to 7807 seeds/m2. Mean species richness also differed significantly among the vegetation classes. Forty-two species were found to be common to the seed banks and the standing vegetation; however, correspondence between species numbers and composition of the seed banks and the standing vegetation was poor. Although most of the species that germinated in the seed banks were herbs and grasses, they can develop a vegetative cover and contribute to reduction of soil erosion. Regeneration of the tree species (some of which have seed viability up to four years) however, requires both time and the presence of mature individuals. Together with hillside closure and soil conservation measures (e.g., terracing), planting of native woody seedlings might help to expedite rehabilitation of degraded hillslopes devoid of trees and shrubs. [source]

    The Importance of Where to Dump the Refuse: Seed Banks and Fine Roots in Nests of the Leaf-Cutting Ants Atta cephalotes and A. colombica,

    BIOTROPICA, Issue 1 2000
    Alejandro G. Farji-Brener
    ABSTRACT The location of the nutrient-rich organic refuse produced by a leaf-cutting ant colony varies among ant species. Atta cephalotes locate their organic refuse in subterranean chambers, whereas A. colombica place their organic refuse on the soil surface near the nest. We studied the effect of the absence or presence of external organic refuse on the abundance of fine roots and seed bank composition in the superficial horizons of ant nests. We sampled soils from ant nests or dumps and adjacent areas of 15 adult nests of A. cephalotes at La Selva (LS), Costa Rica, and of 15 of A. colombica nests on Barro Colorado Island (BCI), Panama. Soils from A. cephalotes nests did not differ from adjacent soils in abundance of fine-root and seed diversity. In contrast, organic refuse from A. colombica nests was less diverse in seed composition (due to the great abundance of Miconia argentea) and had a greater abundance of fine roots than adjacent areas. Thus the external location of the ant-nest organic refuse is potentially important in determining the different types of plant recolonization in abandoned or dead ant nests. The relative abundance of these Atta species may influence the structure and/or composition of tropical forests. RESUMEN En las hormigas cortadoras de hojas, la ubicación de los desechos orgánicos ricos en nutrientes producidos por el hongo que cultivan varía segun la especie. Mientras Atta cephalotesubica sus desechos orgánicos en cámaras subterráncas, A. colombicalos coloca sobre la superficie del suelo cerca del nido. Nosotros estudiamos el efecto de la presencia o ausencia de desechos orgánicos externos sobre la abundancia de raíces finas y la composición del banco de semillas en los suelos superficiales cerca de los hormigueros. Para ello sacamos muestras de basureros o suelo superficial en 15 nidos y areas adjacentes de A. cephalotesen La Selva (LS), Costa Rica, y en 15 nidos de A. colombica ubicados en Barro Colorado (BCI), Panamá. Los suelos de A. cephalotesno difirieron de los suelos adjacentes en abundancia de raíces finas ni en la diversidad de semillas. Por el contrario, los desechos orgánicos externos en nidos de A. colombicafueron menos diversos en composición de semillas (debido principalmente a la gran dominancia de Miconia argentea) y tuvieron una mayor concentración de raices finas que los suelos adyacentes. La ubicación de los desechos es poten-cialmente importance en determinar los diferentes tipos de plantas que pueden recolonizar los nidos abandonados o muertos. Por lo tanto, la abundancia relativa de estas especies de Atta pueden influir en la estructura y/composicion de los bosques tropicales. [source]

    Seed bank, seed dispersal and vegetation cover: Colonization along a newly-created river channel

    JOURNAL OF VEGETATION SCIENCE, Issue 5 2006
    A.M. Gurnell
    Stace (1999) Abstract Question: What is the relative importance of the initial seed bank and subsequent seed dispersal for floristic composition of bank vegetation two years after creation of a newly-cut reach of a river channel? Location: River Cole, West Midlands, United Kingdom. Methods: We took bank and bed sediment samples from a 0.5-km reach of a new river channel cut into intact flood-plain. After river diversion, seed samples deposited on artificial turf mats placed on the river banks and flood-plain edge were taken in summer and winter 2002 and 2003. Seed rain samples from funnel traps were taken during summer 2002 and 2003. We undertook greenhouse germination trials to assess viable seed species within these samples. In summer 2004, we surveyed river bank vegetation. Agglomerative cluster analysis was used to investigate floristic similarity between seed bank, seed rain, seed deposition samples and final bank vegetation cover. DCA was used to explore contrasts between the samples and to assess whether these reflected interpretable environmental gradients. Results: Seed rain samples contained a small subset of species in the summer depositional samples. 38 species were found within the final vegetation, the seed bank, and at least one of the four sets of depositional samples; a further 30 species not present in the seed-bank samples were present in at least one of the four sets of depositional samples and the final vegetation. Floristic composition of the vegetation was most similar to the depositional samples from winter 2002 and 2003 and summer 2003. DCA axis 1 reflected a time sequence from seed-bank samples through depositional samples to the final vegetation. Conclusions: Newly cut river banks were colonized rapidly. Seed remobilization and hydrochorous transport from the upstream catchment are important for colonization. Species richness was highest in samples deposited during winter when high river flows can remobilize and transport viable seeds from upstream. This process would also have enhanced the species richness of seed production along the banks during the second summer (2003). [source]

    The role of the seed bank, seed rain and the timing of disturbance in gap regeneration

    JOURNAL OF VEGETATION SCIENCE, Issue 1 2005
    R.J. Pakeman
    Abstract. Question: Does the degree and timing of disturbance contribute significantly to the pattern and process of regeneration in plant communities as a consequence of the availability and number of species of propagules present? Location: Acid grassland at 230 m a.s.l., eastern Scotland, UK. Methods : Plots were surface disturbed or had their soil profile inverted at monthly intervals at 12 dates during a year. Seed bank and seed rain were assessed at each treatment time. The effect of disturbance intensity and timing on the regenerating vegetation was assessed. Results: Removing the seed bank significantly slowed regeneration, as it contributed 43 % of developing cover after one year where it was present. At an individual seed level, seed in the seed rain had a much higher likelihood of contributing to the regenerating vegetation than a seed in the seed bank. Some species showed a reliance on the seed bank for regeneration, and hence there was a significant difference in the vegetation that developed between plots with the seed bank intact and those where it was removed. Winter disturbed plots (little seed rain) had slower rates of re-vegetation than summer disturbed plots. Timing had little effect on species composition, though a significantly higher cover of perennial forb species developed on the winter disturbed plots. Conclusion: Removing the contribution of the seed bank had a greater effect on the composition of regenerating vegetation than the effect of seasonal variation on the seed rain. [source]

    Size traits and site conditions determine changes in seed bank structure caused by grazing exclusion in semiarid annual plant communities

    ECOGRAPHY, Issue 1 2006
    Yagil Osem
    1. Contrasting patterns of change in the seed bank of natural grasslands are frequently found in response to grazing by domestic herbivores. Here, we studied the hypotheses that a) patterns of change in seed bank density and composition in response to grazing depend on spatial variation in resource availability and productivity, and b) that variation among species in patterns of seed bank response to grazing is linked to differences in species size traits (i.e. size of plant, dispersal unit and seed). 2. Effects of sheep grazing exclusion on the seed bank were followed during five years in a semiarid Mediterranean annual plant community in Israel. Seed bank density and composition were measured in autumn, before the rainy season, inside and outside fenced exclosures in four neighboring topographic sites differing in vegetation characteristics, soil resources and primary productivity: Wadi (dry stream terraces, high productive site), Hilltop, South- and North-facing slopes (less productive sites). 3. Topographic sites differed in seed density (range ca 2500,18000 seed m,2) and in seed bank response to grazing exclusion. Fencing increased seed density by 78, 51 and 18% in the Wadi, South- and North-facing slopes, respectively, but had no effect in the Hilltop. At the species level, grazing exclusion interacted with site conditions in determining species seed bank density, with larger or opposite changes in the high productive Wadi compared to the other less productive sites. 4. Changes in seed bank structure after grazing exclusion were strongly related to species size traits. Grazing exclusion favored species with large size traits in all sites, while seed density of tiny species decreased strongly in the high productive Wadi. Species with medium and small size traits showed lesser or no responses. 5. The size of plants, dispersal units and seeds were strongly correlated to each other, thus confounding the evaluation of the relative importance of each trait in the response of species to grazing and site conditions. We propose that the relative importance of plant size vs seed size in the response to grazing changes with productivity level. [source]

    Seedling dynamics of shrubs in a fully closed temperate forest: greater than expected

    ECOGRAPHY, Issue 5 2004
    N. A. Laskurain
    Shrub seedling emergences were studied in a beech-birch forest in the Basque Country (Spain). During four years (1998,2001) all emerging shrubs were tagged and regularly monitored in 198 1 m2 plots. Seedling emergence was intense during the entire study period and primarily occurred in early spring. Emerging seedlings mainly belonged to Hedera helix, Rubus gr. glandulosus and several heath species (including genera Erica, Calluna and Daboecia). In contrast, some dominant species components of the shrub layer (Vaccinium myrtillus and Lonicera periclymenum) showed no emergences. While small seeded species (heath species and Rubus) showed clear microsite preferences, avoiding litter for emergence, that was not the case of large seeded Hedera helix. Strict microsite requirements appear clearly associated with having seed bank, suggesting that this trait may allow these species to select favourable microenvironment prior to germination. Average life varied largely among the different taxa. It was very low for Rubus (7.4 months) and heath (4.9), and high for Hedera seedlings (23.1). Final survival was extremely low in the case of small-seeded species. Survival of Hedera seedlings was high, although their growth was very low, suggesting the existence of a conspicuous seedling bank. Our results clearly show that several shrubs species have dramatic seedling dynamics in full closed forest stands. Small seeded species preferentially emerge on bare surfaces in early spring from the soil seed banks. On the other hand, Hedera seedlings are able to emerge on litter and maintain a conspicuous seedling bank based on an efficient dispersal capability. [source]

    Comparative seed ecology of the endangered shrub, Pimelea spicata and a threatening weed, Bridal Creeper: Smoke, heat and other fire-related germination cues

    ECOLOGICAL MANAGEMENT & RESTORATION, Issue 1 2003
    Anthony J. Willis
    SummaryPimelea spicata R. Br. is a nationally listed endangered Australian shrub threatened with extinction by habitat fragmentation and environmental weed invasion. Bridal Creeper (Asparagus asparagoides L. W. Wight) is the primary weed threat to the largest remaining populations of P. spicata in the Cumberland Plain. Fire, as part of an integrated pest management program, offers the potential to stimulate P. spicata populations while controlling Bridal Creeper. It is important, therefore, to understand how the components of fire affect the germination and growth of both species. Using laboratory experiments we investigated the effects of smoke, heat, ash and/or light on the germination of P. spicata and Bridal Creeper. We found a significant promotive effect of smoke and indication of an inhibitory heat shock (90°C for 10 min) effect on the germination of P. spicata seeds. The response of Bridal Creeper seeds to the same factors was complex; while the results of one experiment suggested an inhibitory effect of smoke and a promotive effect of heat, subsequent trials were contradictory, implying that Bridal Creeper, like many weeds, is able to germinate under a wide range of environmental conditions. Other experiments investigated the optimal germination temperature and innate dormancy of P. spicata in the absence of fire-related germination cues. Of the incubation temperatures investigated, the optimal diurnally fluctuating regime for P. spicata germinations was 10°C and 20°C in the night and day, respectively. The innate dormancy of freshly produced seeds disappeared after 3 months. In contrast to Bridal Creeper, we found a persistent germinable seed bank of about 97 P. spicata seeds/m2 located in the top 5 cm of the soil profile. While fire alone is unlikely to kill Bridal Creeper plants, fire may help to manage local infestations of the weed by limiting germination and providing opportunity for herbicide treatment of regrowth. [source]

    Biogeography of wetland rice methanotrophs

    ENVIRONMENTAL MICROBIOLOGY, Issue 4 2010
    Claudia Lüke
    Summary We focused on the functional guild of methane oxidizing bacteria (MOB) as model organisms to get deeper insights into microbial biogeography. The pmoA gene was used as a functional and phylogenetic marker for MOB in two approaches: (i) a pmoA database (> 4000 sequences) was evaluated to obtain insights into MOB diversity in Italian rice paddies, and paddy fields worldwide. The results show a wide geographical distribution of pmoA genotypes that seem to be specifically adapted to paddy fields (e.g. Rice Paddy Cluster 1 and Rice Paddy Cluster 2). (ii) On the smaller geographical scale, we designed a factorial experiment including three different locations, two rice varieties and two habitats (soil and roots) within each of three rice fields. Multivariate analysis of terminal restriction fragment analysis profiles revealed different community patterns at the three field sites, located 10,20 km apart. Root samples were characterized by high abundance of type I MOB whereas the rice variety had no effect. With the agronomical practice being nearly identical, historical contingencies might be responsible for the field site differences. Considering a large reservoir of viable yet inactive MOB cells acting as a microbial seed bank, environmental conditions might have selected and activated a different subset at a time thereby shaping the community. [source]

    Flooding, soil seed bank dynamics and vegetation resilience of a hydrologically variable desert floodplain

    FRESHWATER BIOLOGY, Issue 2 2006
    SAMANTHA J. CAPON
    Summary 1. This paper explores soil seed bank composition and its contribution to the vegetation dynamics of a hydrologically variable desert floodplain in central Australia: the Cooper Creek floodplain. We investigated patterns in soil seed bank composition both temporally, in response to flooding (and drying), and spatially, with relation to flood frequency. Correlations between extant vegetation and soil seed bank composition are explored with respect to flooding. 2. A large and diverse germinable soil seed bank was detected comprising predominantly annual monocot and annual forb species. Soil seed bank composition did not change significantly in response to a major flood event but some spatial patterns were detected along a broad flood frequency gradient. Soil seed bank samples from frequently flooded sites had higher total germinable seed abundance and a greater abundance of annual monocots than less frequently flooded sites. In contrast, germinable seeds of perennial species belonging to the Poaceae family were most abundant in soil seed bank samples from rarely flooded sites. 3. Similarity between the composition of the soil seed bank and extant vegetation increased following flooding and was greatest in more frequently flooded areas of the floodplain, reflecting the establishment of annual species. The results indicate that persistent soil seed banks enable vegetation in this arid floodplain to respond to unpredictable patterns of flooding and drying. [source]

    The specialist seed predator Bruchidius dorsalis (Coleoptera: Bruchidae) plays a crucial role in the seed germination of its host plant, Gleditsia japonica (Leguminosae)

    FUNCTIONAL ECOLOGY, Issue 2 2002
    K. Takakura
    Summary 1,This paper describes the germination mechanism of hard seeds of a species of honey locust, Gleditsia japonica, which can germinate only when externally damaged, in relation to four germinating factors: feeding damage by two specialist seed predators, a bean weevil (Bruchidius dorsalis) and a cydid bug (Adrisa magna); feeding damage by a generalist seed predator, a wild mouse (Apodemus speciosus); and physical damage. 2,In laboratory experiments, both the bean weevil and physical damage facilitated germination, while damage by the cydid bug and wild mouse did not. 3,In contrast to laboratory findings, field censuses of G. japonica seed survival revealed that more than 99% were damaged either by B. dorsalis or A. magna. Therefore, less than 0·5% of the seeds remained intact, preventing formation of a seed bank. 4,In addition, all germinating seeds found in the field contained B. dorsalis larvae. 5,These results strongly suggest that damage by B. dorsalis is a prerequisite for G. japonica germination, in contrast to the conventional view that physical disturbance, possibly flooding, is the primary germinating factor for hard seeds. [source]

    Climate change and bet-hedging: interactions between increased soil temperatures and seed bank persistence

    GLOBAL CHANGE BIOLOGY, Issue 10 2009
    MARK K. J. OOI
    Abstract In order to predict the long-term consequences of climate change, it is necessary to link future environmental changes to mechanisms that control plant population processes. This information can then be incorporated into strategies to more accurately model climate change impacts on species or to estimate future extinction risks. We examined the impact of increased temperatures on the longevity and dynamics of the persistent soil seed banks of eight ephemeral species from arid Australia. We found that the predicted global temperature increases under climate change will be reflected in increased soil temperatures, and that seeds in the soil seed bank will be exposed to long durations of high temperatures over the summer months. Three of the eight species studied had significantly greater levels of germination after exposure to predicted increased soil temperatures. Another species displayed a dramatic decrease in seed viability after such exposure. The capacity of such species to use the seed bank to bet hedge against rainfall events that cause germination but are insufficient to allow plant maturation, is compromised by increased germinability and subsequent loss or reduction of seed bank persistence. These predicted changes in the dynamics of soil seed banks increase the risk of local extinctions of these species, while the composition of the community may be altered by changes in species abundance. Our results show that the risk spreading mechanism provided by persistent seed banks could be compromised by the mechanistic impact of forecast temperature increases in arid habitats, and highlight the need to understand mechanisms that control population dynamics when attempting to address likely future impacts of climate change on biodiversity. [source]

    Transgenic weed beets: possible, probable, avoidable?

    JOURNAL OF APPLIED ECOLOGY, Issue 4 2002
    Benoît Desplanque
    Summary 1Weed beets pose a serious problem for sugar beet Beta vulgaris crops. Traditionally, the only efficient method of weed control has been manual removal, but the introduction of transgenic herbicide-tolerant sugar beets may provide an alternative solution because non-tolerant weed beets can be destroyed by herbicide. We evaluated the possibility that new, transgenic, weed beets may arise by gene flow between wild and crop plants. 2In a study area in northern France, weed beets were present in variable densities in sugar beet fields of up to 80 weed beet plants m,2. Weed beets arise from a long-lived seed bank, with seeds germinating from depths of 5 cm or less. In addition, diploid F1 crop,wild hybrids and triploid variety bolters (individuals with a low vernalization requirement) were present in low densities in virtually all sugar beet fields. We found gene flow to be possible between all forms, illustrated by both overlapping flowering periods in the field and successful controlled cross-pollinations. 3The F1 crop,wild hybrids result from pollination in the seed-production region by wild plants possessing the dominant bolting allele B for flowering without experiencing a period of cold. In the case of a transgene for herbicide tolerance incorporated into male-sterile seed-bearer plants, such hybrids will contain both the herbicide-tolerance and the bolting allele. Contamination of the fields by transgenic weed beets will be the result unless bolters are removed manually. The same will apply in the case of a cytoplasmically inherited transgene. 4Incorporation of the transgene into the pollinator plants will prevent the immediate formation of transgenic weed beets. However, in sugar beet fields, variety bolters may successfully cross-pollinate with weed beets in neighbouring fields. The use of diploid pollinator plants instead of tetraploids will considerably enhance gene flow towards wild beets, and is not, therefore, an attractive option. 5In conclusion, the appearance of transgenic weed beets is possible but can best be retarded if the transgene for herbicide tolerance is incorporated into the tetraploid pollinator breeding line. [source]

    Restoration of species-rich grassland on arable land: assessing the limiting processes using a multi-site experiment

    JOURNAL OF APPLIED ECOLOGY, Issue 2 2002
    Richard F. Pywell
    Summary 1Agricultural intensification has resulted in the reduction and fragmentation of species-rich grasslands across much of western Europe. 2We examined the key ecological processes that limit the creation of diverse grassland communities on ex-arable land in a multi-site experiment over a wide variety of soil types and locations throughout lowland Britain. 3The results showed it was possible to create and maintain these communities successfully under a hay-cutting and grazing management regime. Furthermore, there was a high degree of repeatability of the treatment effects across the sites. 4Lack of seed of desirable species was the key factor limiting the assembly of diverse grassland communities. Sowing a species-rich seed mixture of ecologically adapted grassland plants was an effective means of overcoming this limitation. Community assembly by natural colonization from the seed bank and seed rain was a slow and unreliable process. However, there was no evidence to suggest that sowing a species-poor grass-dominated seed mixture made the vegetation any less susceptible to colonization by desirable species than allowing natural regeneration to take place. 5Deep cultivation caused significant reductions in soil P and K concentrations across the sites. This had a significant beneficial effect on the establishment and persistence of sown forbs in all years. It also resulted in a significant reduction in the number of unsown weedy grasses. However, for both variables these differences were very small after 4 years. 6Sowing a nurse crop significantly reduced the number of unsown grass species, but had no beneficial effect on the establishment of desirable species. 7Treatments sown with the species-rich seed mixture following deep cultivation corresponded most closely to the specified target communities defined by the UK National Vegetation Classification. Natural regeneration and treatments sown with the species-poor seed mixture were much less similar to the target. The sites on circum-neutral soils achieved the greatest degree of similarity to the target. Those on calcareous and acid soils failed to achieve their targets and most closely resembled the target for neutral soils. This reflected the poor performance of the sown preferential species for these communities. [source]

    Reciprocal distribution of two congeneric trees, Betula platyphylla var. japonica and Betula maximowicziana, in a landscape dominated by anthropogenic disturbances in northeastern Japan

    JOURNAL OF BIOGEOGRAPHY, Issue 12 2005
    Katsuhiro Osumi
    Abstract Aim, Information has been compiled on disturbance regimes and the life-history characteristics of Betula platyphylla var. japonica (Miq.) Hara and B. maximowicziana Regel to investigate the impact of humans on the present distribution patterns of these two congeneric tree species. Location, The study area is in the central region of the northern Kitakami Mountain Range, located in the northeast of Honshu Island, Japan. Methods, First, the present distributions of B. maximowicziana and B. platyphylla var. japonica were mapped at the landscape scale. To examine the factors affecting the distribution patterns, topographic features and past land use were taken into account. Second, life-history traits of both species were clarified at various growth stages either by fieldwork or through a literature search. Previous studies have provided some information on seed production, seed dispersal, seedling dynamics, sprouting, and growth. In the present study, field observations and experiments were conducted regarding seed-bank formation, size and age at reproduction, and the life span of canopy trees. Results,Betula platyphylla var. japonica and B. maximowicziana were spatially segregated in the studied landscape (14,000 ha). The distribution of each species was correlated more strongly with land use at the beginning of the twentieth century than with site environmental factors such as altitude or slope angle. Betula platyphylla var. japonica was distributed more frequently on former grasslands, whereas B. maximowicziana was almost exclusively limited to past old-growth forests. As typical pioneers, the two species showed similar life-history traits but differed in several critical points. Betula platyphylla var. japonica has a vigorous sprouting ability, which might increase its resistance to burning and logging, whereas B. maximowicziana forms a persistent seed bank in the soil, indicating an advantage in regenerating in disturbances found in forest communities. Other critical differences were detected in age-related characteristics such as minimum age of reproduction and life span. Main conclusions, The earlier reproductive maturity and the shorter life span of B. platyphylla var. japonica indicate a shorter population cycle than that for B. maximowicziana. The latter would be excluded from grasslands that were burned frequently, as a result of the longer time span before initial reproduction and its poor sprouting ability. In contrast, B. platyphylla var. japonica would be excluded from old-growth forests, where disturbance was infrequent, owing to its shorter life span and lack of a persistent seed bank. [source]

    Spatial and temporal variability in seed dynamics of machair sand dune plant communities, the Outer Hebrides, Scotland

    JOURNAL OF BIOGEOGRAPHY, Issue 5 2001
    N. W. Owen
    Aim The subjects of seed banks and seed rain represent comparatively neglected areas of biogeography, yet at the community scale, exhibit interesting patterns in both space and time. This paper describes the seed bank and seed rain characteristics of the machair sand dune communities of the Outer Hebrides. As well as looking at individual species distributions and variability, the seed banks and seed rain are examined in terms of their detailed subcommunity composition and its local spatial and temporal variation. The machair plant (sub)communities show extensive degrees of anthropogenic modification because of past and present agricultural management, including cultivation for cereals over wide areas and for potatoes in large numbers of ,lazy beds' or small patches. Thus over the historical period, large areas of machair have undergone regular ploughing and cultivation, which have provided the opportunity for a patchwork of secondary succession to occur. This pattern continues to the present day. Furthermore, most other non-cultivated plant (sub)communities are intensively grazed, primarily by cattle and also by sheep and rabbits. Location South Uist, the Outer Hebrides, north-west Scotland. Methods At two carefully selected locations, a range of these various successional subcommunities have been sampled for their seed banks, by taking cores and for their seed rain, by using specially designed traps located where each seed bank sample was removed. This paired sampling strategy allowed direct comparison of the seed bank and the seed rain. Both individual species distributions and the community assemblages of seed bank/seed rain species are examined in space and time using techniques of numerical classification [two-way indicator species analysis (TWINSPAN)] and ordination [detrended correspondence analysis (DCA)]. Results and conclusions There is considerable heterogeneity within and between machair subcommunities in terms of seed bank and seed rain characteristics. The soil seed banks and seed rain of the agriculturally disturbed machair subcommunities are consistently more dense and more species rich than non-cultivated areas of the machair. Overall, machair seed banks are small and stable with no discernible seasonal trends in either size or species composition. In contrast, seed rain on the machair is characterized by a distinct temporal trend. Both seed banks and seed rain are potentially very poor sources of propagules for recolonization following disturbance, indicating that the majority of revegetation following anthropogenic and/or environmental interference is through vegetative reproduction. [source]

    The production, storage and viability of seeds of Acacia karroo and A. nilotica in a grassy savanna in KwaZulu-Natal, South Africa

    AFRICAN JOURNAL OF ECOLOGY, Issue 3 2003
    Michele Walters
    Abstract African Acacias are often major contributors to the progressive increase in the woody component of savannas, a phenomenon commonly referred to as bush encroachment. They produce large quantities of seed and may have large soil-stored seed banks. In Hluhluwe,Umfolozi Park, the number of adult Acacia nilotica trees per hectare far exceed that of A. karroo adults. The relative dominance is reversed in the juvenile stage with A. karroo outnumbering A. nilotica threefold outside closed woodlands. Acacia karroo trees were smaller than A. nilotica trees on average, but produced more seeds for a given basal diameter size class. Acacia karroo showed less bruchid infestation than A. nilotica at all stages of pod development. Unlike A. nilotica, a proportion of A. karroo seeds was able to germinate after bruchid attack. We detected no difference between the two species in the soil-stored seed bank or in the viability of seeds found in the seed bank. Résumé Les acacias africains sont souvent des contributeurs majeurs de l'augmentation progressive des composants ligneux de la savane, un phénomène connu comme l'envahissement du bush. Ils produisent de grandes quantités de semences et il peut y avoir de grands stocks de semences dans le sol. Dans le Parc de Hluhluwe-Umfolozi, le nombre d'Acacia nilotica adultes par hectare dépasse de loin celui d'A. karroo adultes. Cette dominance relative est inversée au stade juvénile, les A. karrooétant trois fois plus nombreux que les A. nilotica en dehors des forêts fermées. Les Acacia karroo sont en moyenne plus petits que les A. nilotica, mais ils produisent plus de graines pour une classe de diamètre donnée. Les A. karroo présentent une moindre infestation par les bruchidés que les A. nilotica, à tous les stades de développement de la gousse. Contrairement aux graines d'A. nilotica, une certaine proportion de celles d'A. karrooétaient capables de germer après une attaque de bruchidés. Nous n'avons décelé aucune différence entre les deux espèces en ce qui concerne le stock de graines dans le sol ou la viabilité des semences que l'on y trouve. [source]

    Temporal and spatial genetic variation in a metapopulation of the annual Erysimum cheiranthoides on stony river banks

    JOURNAL OF ECOLOGY, Issue 1 2009
    Olivier Honnay
    Summary 1Metapopulation dynamics , the recurrent extinction and colonization in spatially discrete habitats , is expected to strongly affect within and between population genetic diversity. So far, however, accounts of true plant metapopulations are extremely scarce. 2We monitored the colonization and extinction dynamics of an assemblage of populations of the annual Erysimum cheiranthoides on stony river banks during three consecutive years. Each year, winter flooding drives some populations to extinction, while vacant banks may become colonized. We describe the dynamics of these ephemeral populations using amplified fragment length polymorphism (AFLP) markers to quantify changes in the metapopulation genetic structure over time, and assessing the direction and relative amount of migration and colonization events. 3Average extinction and colonization rates were high (0.39 and 0.34, respectively). While population genetic differentiation (FST) tripled from 0.06 in 2005 to 0.17 in 2007, total metapopulation genetic diversity remained fairly constant through the years. Genetic assignment analyses allowed assigning more than 50% of the genotyped individuals to populations extant the year before. Colonizing individuals originated from different source populations (, << 1) and there was considerable evidence of upstream seed dispersal. 4The degree and pattern of spatial genetic structure varied between years and was related to variation in the flooding intensity of the Meuse River through the years. Possibly, activation of the soil seed bank also played a role in structuring the genetic make-up of the populations. 5Because migration and colonization events were qualitatively equal, and colonizing individuals originated from different sources, the increase in FST was in agreement with previous theoretical work. Very high migration and colonization rates, and the short monitoring period, may explain why there was no loss of genetic diversity from the metapopulation through recurrent extinction and colonization events. 6Synthesis. This study gives one of the first accounts of the dynamics of a true plant metapopulation. Temporal monitoring of genetic variation gave evidence of extensive and bidirectional seed dispersal, highly variable and increasing genetic differentiation, and rather constant within population genetic diversity. An important suggestion from this research is to include a dormant seed stage in further theoretical work on (meta) population genetics. [source]

    Population dynamics in Digitalis purpurea: the interaction of disturbance and seed bank dynamics

    JOURNAL OF ECOLOGY, Issue 6 2007
    NINA SLETVOLD
    Summary 1Plant ecologists have long since realized that the persistence of many facultative biennial plants depends upon disturbance. However, we still have a limited knowledge of the population-level effects of disturbance, and the connection between adult and seed bank dynamics. 2Using data from a 3-year demographic study combined with experimental gap-opening in a large population of Digitalis purpurea, we parameterized stochastic transition matrix models in ,disturbed' vs. ,undisturbed' areas. We simulated different gap sizes (fraction of population that was disturbed) and temporal disturbance patterns (constant, random, regular and irregular return intervals) and evaluated the effects on population growth rate and seed bank dynamics. To explore seed bank importance we used two alternatives for seed bank survival rate (0.75/0.35) and three alternatives for seed bank recruitment fraction (0.9/0.5/0.1). 3Observed background recruitment levels were insufficient to ensure a positive population growth rate. Increased amounts of gap-opening led to higher growth rates, and population persistence was predicted at moderate disturbance levels if seed bank survival was high (0.75). 4Temporal disturbance pattern affected model results; random and interval scenarios resulted in lower population growth rates and higher extinction risks than constant scenarios of the same average disturbance level. Small and frequent disturbances led to considerably higher growth rates than large and rare disturbances. 5Stochastic elasticity analyses identified the seed bank as the most important life cycle stage with respect to population growth and persistence in most scenarios, and its relative impact was positively related to seed bank survival rate and negatively related to disturbance level. Variation in the recruitment fraction from seed bank vs. seed rain affected both population growth rate and elasticity patterns, indicating the large impact of spatial variation in seed bank density. 6Synthesis: Despite the existence of a large seed bank, our data suggest that recruitment may be locally seed-limited due to a patchy seed bank structure. Local population development may consequently differ widely from gap to gap. These results illustrate how spatial structures in both seed bank, adult population and gap formation interact to shape plant population dynamics, as well as the occurrence of microsite- vs. seed-limitation. [source]

    Spatial genetic structure links between soil seed banks and above-ground populations of Primula modesta in subalpine grassland

    JOURNAL OF ECOLOGY, Issue 1 2006
    A. SHIMONO
    Summary 1The spatial genetic structure of soil seed banks establishes the initial template for development of spatial genetic structure in above-ground plants, but is rarely evaluated. 2We used kinship coefficients to analyse the fine-scale spatial genetic autocorrelation of plants and of seed banks from different soil depths for Primula modesta at a subalpine fen site on Mt Asama, central Japan. 3The spatial genetic structure of surface seeds (0,1 cm depth) was significant, while deeper seeds (1,5 cm depth) had no significant genetic structure. We also detected a more pronounced spatial genetic association between the surface seeds and flowering genets than between the deeper seeds and flowering genets. 4These results suggest that the surface seed bank accounts for a large proportion of the previous season's seed dispersal and therefore represents the transient seed bank, whereas the deeper (persistent) seed bank pools the reproductive output of multiple generations. 5Directional analysis indicated that secondary dispersal by running water modifies the spatial genetic structure and extends dispersal distances. Over time, this may impact on the spatial pattern of soil seeds, possibly accounting for the absence of spatial genetic structure in deeper seeds. 6Emerging seedlings and flowering ramets were strongly clustered together at distances up to 20 cm. Surviving seedlings were aggregated at short distances because of the patchy spatial distribution of safe sites for establishment, allowing development and strengthening of the marked fine-scale spatial genetic structure. [source]

    The effect of initial seed density on the structure of a desert annual plant community

    JOURNAL OF ECOLOGY, Issue 3 2002
    Christopher J. Lortie
    Summary 1,Few experiments directly test the role of density dependence in natural plant communities. 2,We tested (i) whether different initial seed densities of the entire seed bank of an annual plant community affected performance (emergence, mean plant biomass and survival) and (ii) whether density-dependent processes were operating within the communities. We also tested whether life-stage, year and soil moisture (both on a topographic gradient and in an experimental manipulation) influenced the effects of seed density. 3,We considered two distinct phases: seed to emergent seedlings, and emergent seedlings to established plants. 4,The seed bank was collected from a semistabilized sand dune in the Negev Desert, Israel. This was added to sieved sand in plots at the same site at four different initial seed densities: 1/16×, 1/4×, 1× (natural seed density) and 2×. The experiment was repeated for three consecutive growing seasons. 5,Emergence of seedlings was significantly influenced by initial seed density in all 3 years, with higher initial seed densities having lower rates of emergence. 6,Mean final plant size was negatively density dependent and consistently unaffected by the initial seed density sown. 7,In general, there were no strong interactions of topographic position with initial seed density, processes within the vegetation were not density dependent and the experimental addition of water did not influence any of the performance measures tested. Density-dependent processes vary from year to year, while moisture effects do not. 8,We conclude that seedling emergence and some processes in the established plant community are density dependent, but the established plant community is also affected by other processes, such as resource limitation. [source]

    Fruit dispersal and seed banks in Atriplex sagittata: the role of heterocarpy

    JOURNAL OF ECOLOGY, Issue 2 2001
    Bohumil Mandák
    Summary 1Atriplex sagittata, an arly succesional, annual species of disturbed habitats in Central Europe, produces three types of fruits. We studied the differences in dispersal between the fruit types in order to investigate their ecological roles. 2The typical positive relationship between dispersal ability and germinability is not found in this species. Type A (ebracteate) fruits produced deeply dormant seeds and had the lowest dispersal potential, but of the two fruits with bracts, type B, with dormant seeds, was better dispersed by both water and wind than type C, which produces non-dormant seeds. 3Wind, temperature and precipitation have significant effects on fruit release but their effects differ between fruit types. The release of fruit types with bracts was positively correlated with wind whereas all fruit types tended to be negatively correlated with precipitation and temperature range. 4Type C fruit, which contains non-dormant seed, are absent from the soil in summer and have a Type II transient seed bank. Type A and B fruits, containing dormant seeds, form a persistent seed bank. 5Heterocarpy, where fruit types show distinct ecological behaviour, enables colonizing species such as A. sagittata to survive both major disturbance (by ensuring that some seeds persist) and unfavourable conditions (by spreading germination over a long period). 6In A. sagittata, seed dynamics can be explained by the germination behaviour of seeds produced by the three types of fruit. All fruit types mature in autumn, but few of Type A fall from the mother plant until spring, when germination is probably inhibited because of insufficient stratification. Type C fruit, however, show peak dispersal in winter and the majority of these non-dormant seeds are able to germinate as soon as conditions become more suitable. [source]

    Post-dispersal fate of seeds in the Monte desert of Argentina: patterns of germination in successive wet and dry years

    JOURNAL OF ECOLOGY, Issue 6 2000
    Luis Marone
    Summary 1,Patterns of seed germination of grass and forb species were studied in open Prosopis woodland of the central Monte desert (Argentina) during several years, to test the hypotheses that (i) seed germination is positively affected by both rainfall and protection afforded by vegetation cover (a facilitative effect), (ii) the number of surviving plants is positively influenced by rainfall but negatively affected by established vegetation (a competitive effect), and (iii) seed loss from soil banks owing to germination is lower than that caused by granivorous animals. 2,Forb species germinated during restricted periods, either in early autumn or in spring. Grasses, however, germinated throughout the growing season, but because seedlings could not be identified to species level, it was impossible to discern whether different species germinated in particular seasons, or if all grasses germinated in all seasons. Grass and forb germination were generally of similar magnitude, but grass germination increased by an order of magnitude during a summer of unusually abundant rainfall related to an El Niño Southern Oscillation (ENSO) event. 3,Overall, the spatial distribution of neither germinating seeds nor surviving plants could be explained by interactions with established vegetation (facilitation and competition effects, respectively). An alternative explanation may be provided by the distribution of forb and grass seeds in the soil. 4,Seed loss owing to germination was low in both dry and rainy years. For forbs, such loss totalled <,1% of soil-seed reserves, and no forb species suffered losses >,4%. Total grass-seed loss to germination was usually <,0.5%, and the 5% reached in 1997,98 corresponded to an interruption of a prolonged drought by unusually abundant rainfall associated with a reduced seed bank. 5,Grass-seed loss caused by germination was one to two orders of magnitude lower than that reported due to autumn-winter granivory in the central Monte desert. [source]

    Soil seed banks in Mediterranean Aleppo pine forests: the effect of heat, cover and ash on seedling emergence

    JOURNAL OF ECOLOGY, Issue 4 2000
    Ido Izhaki
    Summary 1 ,East Mediterranean Aleppo pine (Pinus halepensis) forests are subjected to periodic stand-replacing fires. We simulated two of the effects of fire on the germinable soil seed bank in four pine stands on Mt. Carmel, Israel, that differed in their post-fire ages. Soil samples were heated to 100 °C, or covered by pine ash. Vermiculite was used to simulate litter cover. 2 ,Heat exposure increased overall seedling density, richness and taxon diversity in all stands, but density of annual taxa (e.g. grasses and legumes) were not clearly affected. 3 ,Ash cover dramatically decreased germination of all taxa and highest germination was achieved with heating and no cover. Vermiculite cover resulted in intermediate germination levels. 4 ,The combined effect of heat exposure and ash cover, simulating a post-fire situation under a canopy of pine, reduced the germination level of all taxa in the soil seed bank. However, it also creates conditions that facilitate the establishment of pine seedlings from the canopy stored seed bank. [source]

    Seed dynamics of the mast seeding tussock grass Ampelodesmos mauritanica in Mediterranean shrublands

    JOURNAL OF ECOLOGY, Issue 3 2000
    Montserrat Vilà
    Summary 1,The Mediterranean perennial grass Ampelodesmos mauritanica may have the potential to expand its range. We analysed temporal variability of its reproductive components (seedfall, seed bank, seed predation, seed germination, seedling emergence, survival and growth) in three microsites (open areas, beneath Ampelodesmos and beneath shrubs) at two sites. 2,Reproductive components prior to seedling emergence were both closely linked and very similar between microsites within a site. Seedling survival and growth differed between microsites, being lowest in open areas. Recruitment patterns cannot therefore be predicted from seedfall. 3,Abundant seed production in 1996 was followed by successful germination and high seedling survival. In the following (non-masting) year, although Ampelodesmos has a low-density persistent seed bank, recruitment was much lower because germination was low and post-dispersal seed predation was high. 4,Our results suggest that Ampelodesmos reproduction is episodic. Expansion of its distribution may be triggered by intermittent seedling recruitment following masting, but is otherwise constrained by seed limitation, post-dispersal seed predation and a loss of viability in the seed bank. [source]

    Can the seed bank be used for ecological restoration?

    JOURNAL OF VEGETATION SCIENCE, Issue 6 2008
    An overview of seed bank characteristics in European communities
    Abstract 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. [source]

    Dispersal and recruitment dynamics in the fleshy-fruited Persoonia lanceolata (Proteaceae)

    JOURNAL OF VEGETATION SCIENCE, Issue 6 2007
    Tony D. Auld
    Abstract Question: What is the role of dispersal, persistent soil seed banks and seedling recruitment in population persistence of fleshy-fruited obligate seeding plant species in fire-prone habitats? Location: Southeastern Australia. Methods: We used a long-term study of a shrubby, fleshy-fruited Persoonia species (Proteaceae) to examine (1) seed removal from beneath the canopy of adult plants; (2) seedling recruitment after fire; (3) the magnitude and location of the residual soil seed bank; and (4) the implications for fire management of obligate seeding species. We used demographic sampling techniques combined with Generalised Linear Modelling and regression to quantify population changes over time. Results: Most of the mature fruits (90%) on the ground below the canopy of plants were removed by Wallabia bicolor (Swamp wallaby) with 88% of seeds extracted from W. bicolor scats viable and dormant. Wallabies play an important role in moving seeds away from parent plants. Their role in occasional long distance dispersal events remains unknown. We detected almost no seed predation in situ under canopies (< 1%). Seedling recruitment was cued to fire, with post-fire seedling densities 6-7 times pre-fire adult densities. After fire, a residual soil seed bank was present, as many seeds (77-100%) remained dormant and viable at a soil depth where successful future seedling emergence is possible (0-5 cm). Seedling survival was high (> 80%) with most mortality within 2 years of emergence. Plant growth averaged 17 cm per year. The primary juvenile period of plants was 7,8 years, within the period of likely return fire intervals in the study area. We predicted that the study population increased some five-fold after the wildfire at the site. Conclusions: Residual soil seed banks are important, especially in species with long primary juvenile periods, to buffer the populations against the impact of a second fire occurring before the seed bank is replenished. [source]

    Seed bank, seed dispersal and vegetation cover: Colonization along a newly-created river channel

    JOURNAL OF VEGETATION SCIENCE, Issue 5 2006
    A.M. Gurnell
    Stace (1999) Abstract Question: What is the relative importance of the initial seed bank and subsequent seed dispersal for floristic composition of bank vegetation two years after creation of a newly-cut reach of a river channel? Location: River Cole, West Midlands, United Kingdom. Methods: We took bank and bed sediment samples from a 0.5-km reach of a new river channel cut into intact flood-plain. After river diversion, seed samples deposited on artificial turf mats placed on the river banks and flood-plain edge were taken in summer and winter 2002 and 2003. Seed rain samples from funnel traps were taken during summer 2002 and 2003. We undertook greenhouse germination trials to assess viable seed species within these samples. In summer 2004, we surveyed river bank vegetation. Agglomerative cluster analysis was used to investigate floristic similarity between seed bank, seed rain, seed deposition samples and final bank vegetation cover. DCA was used to explore contrasts between the samples and to assess whether these reflected interpretable environmental gradients. Results: Seed rain samples contained a small subset of species in the summer depositional samples. 38 species were found within the final vegetation, the seed bank, and at least one of the four sets of depositional samples; a further 30 species not present in the seed-bank samples were present in at least one of the four sets of depositional samples and the final vegetation. Floristic composition of the vegetation was most similar to the depositional samples from winter 2002 and 2003 and summer 2003. DCA axis 1 reflected a time sequence from seed-bank samples through depositional samples to the final vegetation. Conclusions: Newly cut river banks were colonized rapidly. Seed remobilization and hydrochorous transport from the upstream catchment are important for colonization. Species richness was highest in samples deposited during winter when high river flows can remobilize and transport viable seeds from upstream. This process would also have enhanced the species richness of seed production along the banks during the second summer (2003). [source]

    The fate of seeds in Mediterranean soil seed banks in relation to their traits

    JOURNAL OF VEGETATION SCIENCE, Issue 1 2006
    Juan Traba
    Abstract Question: Is there any change in seed density and species richness in Mediterranean surface soil banks during summer? Are there any relationships between these summer variations and seed traits (weight, length and shape), without and with controlling the phylogenetic effect? Location: Central Spain. Methods: Samples of the surface soil seed bank were collected in two Mediterranean systems, grassland and scrubland, at two points in the year: immediately after the summer production peak and immediately prior to the autumn germination peak. We used Canonical Correspondence Analysis ordination to check for changes in floristic composition and ANOVAs to check for changes in seed density and species richness between summer and autumn samples. We used multiple regression analysis to analyse the relationship between summer variations in soil seed density and form traits, with and without controlling phylogenetic relations. Results: Soil seed density dropped significantly during the summer in the two systems (28% in grasslands, repeated measures ANOVA test; F = 58.19, P < 0.01; 72% in scrublands, repeated measures ANOVA test; F = 75.67, P < 0.001). Species richness, however, only dropped significantly in the scrubland (32%; repeated measures ANOVA test; F = 9.17, P < 0.05). Variation in the floristic composition of the shallow banks was only significant in the scrubland. Changes in shallow bank density were related significantly to seed morphology features, with greater drops in species with heavier seeds in grasslands and species with longer seeds in scrubland. Conclusions: Our results show a substantial loss of seeds in the uppermost soil layer during the summer period between the point of peak production and the autumn germination peak. This drop was clearer in the scrubland than in the grassland. Longer and/or heavier seeds underwent the greatest declines in density at the end of summer, indicating a more intense effect of post-dispersal predation on large-seeded species. [source]