Seed Bank Community Research Articles

Dynamic Analysis of Arbor Species Germinated from Soil Seed Bank under Watering Strategies Driving

The watering gradient is an important factor affecting the composition and structure of the soil seed bank community. The germplasm resources in the soil seed bank have their corresponding water germination intervals. The soil seed bank of Tianjin Guangang Forest Park was selected as the research object and different watering gradients were set to test. Through statistical analysis and regression equation model, we could analyse and evaluate the morphological features of arbor species in soil seed bank under different watering gradients and find out the soil moisture interval which was most suitable for the restoration effect of soil seed bank in Tianjin. The study results showed that: (1) the watering gradient was set to 1000 mL, the arbor population in the experimental dish had the highest plant height, the largest canopy cover and the best arbor community; when the water content was less than 1000 mL, it couldn’t meet the water demand of plant growth and the number of seed germination was greatly reduced; while above 1000mL, the soil was in flooded state, inhibited the germination of some seeds; (2) under the same watering gradients, the average height and canopy cover of Fraxinus chinensis species showed great advantages compared with Robinia pseudoacacia L. and Koelreuteria paniculate species; (3) the average height and canopy cover of three arbor species were positively correlated by regression analysis, and when the watering gradient was set to 1000mL, its correlation was best.

Legacy effects of afforestation on prairie plant and seed bank communities in a northern Canadian prairie

Afforestation resulting from fire suppression, modified grazing, plantation establishment and climate change poses a threat to northern prairie ecosystems. Trees alter the composition and function of plant and soil fauna communities and can compromise the restoration of afforested prairies. To evaluate the hypothesis that legacies of afforestation persist in restored prairie communities and decrease the potential for restoration, we examined the composition, structure, and diversity of plant and seed bank communities along a 20year chronosequence of plantation tree removal from a northern fescue prairie in Riding Mountain National Park, Manitoba, Canada. Tree removal increased the abundance of weedy species in the plant and seed bank communities of restored prairies and plant diversity peaked and declined over the 20year period of passive restoration. As a result, time since tree removal and the encroachment of invasive species were key in explaining the composition of restored prairie communities. Low correlation between the species composition of plant and seed bank communities, including the complete absence of Festuca hallii in restored treatments, demonstrated that legacies of afforestation compromised the potential of seed banks to facilitate prairie restoration. We conclude that tree removal alone is insufficient for the restoration of northern fescue prairies and that, in the absence of active management, the persistence of low-diversity plant and seed bank communities constitutes an important legacy of afforestation and an important barrier to future restoration.

Microbial Community Structure and Functional Potential Along a Hypersaline Gradient.

Salinity is one of the strongest environmental drivers of microbial evolution and community composition. Here we aimed to determine the impact of salt concentrations (2.5, 7.5, and 33.2%) on the microbial community structure of reclaimed saltern ponds near San Francisco, California, and to discover prospective enzymes with potential biotechnological applications. Community compositions were determined by 16S rRNA amplicon sequencing revealing both higher richness and evenness in the pond sediments compared to the water columns. Co-occurrence network analysis additionally uncovered the presence of microbial seed bank communities, potentially primed to respond to rapid changes in salinity. In addition, functional annotation of shotgun metagenomic DNA showed different capabilities if the microbial communities at different salinities for methanogenesis, amino acid metabolism, and carbohydrate-active enzymes. There was an overall shift with increasing salinity in the functional potential for starch degradation, and a decrease in degradation of cellulose and other oligosaccharides. Further, many carbohydrate-active enzymes identified have acidic isoelectric points that have potential biotechnological applications, including deconstruction of biofuel feedstocks under high ionic conditions. Metagenome-assembled genomes (MAGs) of individual halotolerant and halophilic microbes were binned revealing a variety of carbohydrate-degrading potential of individual pond inhabitants.

Seed bank dynamics in wetland complexes associated with a lowland river

The existence of a dormant “bank” of plant seeds plays an important role in maintaining and preserving species and genetic diversity. However, information on the spatial heterogeneity of the pool of dormant seeds among wetland complexes along riverine systems is limited. In this study we collected sediment from 18 wetlands within six wetland complexes along the Murray River, Australia. The germinable, residual and viable seed banks in each wetland complex were assessed by undertaking a germination trial, counting seeds (morphotypes) and viability testing. A diverse and viable seed bank exists within all the complexes however seed bank communities differed among wetland complexes. There was no difference in the viability of seeds within the sediment profile, however more seeds occurred in the surface layers of sediment and communities differed with sediment profile depth. In general, the number of species germinating was fewer than the number of seed morphotypes counted. Management actions need to be targeted not only at preserving the extant plant communities but also to ensure the seed bank is replenished. This may also involve allowing wetlands to dry sufficiently to enable cracking of wetland sediment and seeds to become buried to maximise the longevity of the seed store.

A historical legacy of antibiotic utilization on bacterial seed banks in sediments

The introduction of antibiotics for both medical and non-medical purposes has had a positive effect on human welfare and agricultural output in the past century. However, there is also an important ecological legacy regarding the use of antibiotics and the consequences of increased levels of these compounds in the environment as a consequence of their use and disposal. This legacy was investigated by quantifying two antibiotic resistance genes (ARG) conferring resistance to tetracycline (tet(W)) and sulfonamide (sul1) in bacterial seed bank DNA in sediments. The industrial introduction of antibiotics caused an abrupt increase in the total abundance of tet(W) and a steady increase in sul1. The abrupt change in tet(W) corresponded to an increase in relative abundance from ca. 1960 that peaked around 1976. This pattern of accumulation was highly correlated with the abundance of specific members of the seed bank community belonging to the phylum Firmicutes. In contrast, the relative abundance of sul1 increased after 1976. This correlated with a taxonomically broad spectrum of bacteria, reflecting sul1 dissemination through horizontal gene transfer. The accumulation patterns of both ARGs correspond broadly to the temporal scale of medical antibiotic use. Our results show that the bacterial seed bank can be used to look back at the historical usage of antibiotics and resistance prevalence.

Invasion by Rhododendron ponticum depletes the native seed bank with long-term impacts after its removal

The soil seed bank plays an important role in determining what plant species emerge following the removal of monodominant invasive species. A depleted seed bank may provide a substantial barrier to site restoration, however, little is known about what changes occur in the seed bank during invasion and following clearance. This study used greenhouse germination trials to quantify and compare the seed bank present in 30 Scottish Atlantic oak woodland sites under three treatments: (1) sites featuring dense stands of the non-native invasive shrub Rhododendron ponticum; (2) sites that had been previously subject to dense R. ponticum stands but which had been cleared; and (3) uninvaded control sites. Seed banks of densely invaded and cleared sites had significantly lower species richness than those of uninvaded control sites with a lower abundance of graminoid, and to a lesser extent forb seeds than the uninvaded controls. The seed bank community composition differed significantly between the three site types. Uninvaded sites featured a wide array of species, densely invaded sites were dominated by R. ponticum seeds and cleared sites were dominated by birch (Betula sp.) seeds. Cleared sites contained very few R. ponticum seeds indicating that once effective clearance had been achieved, re-invasion would be unlikely to occur from the soil seed bank. Our findings revealed that the soil seed bank present in cleared sites was very different from the seed bank of uninvaded control sites, with clear implications for site restoration.

Factors affecting soil seed banks of riparian communities in an agricultural ecosystem: potential for conservation of native plant diversity

AbstractQuestionsDo agricultural land use and nitrogen (N) enrichment have negative effects on riparian soil seed banks? What is the potential of the soil seed bank for the conservation and restoration of native riparian plant diversity? Are non‐native dominant grass species affected by agriculture and do they affect species richness?LocationSouth Nation River watershed (an agricultural watershed), Ontario, Canada.MethodsWe examined the riparian above‐ground vegetation at 24 sites located across a large (~4000 km2) North American watershed and identified the corresponding soil seed bank composition from soil cores using the seedling emergence method. The above‐ground vegetation and soil seed bank species compositions were compared in terms of species richness, percentage of non‐native species and a floristic quality index. Factors affecting these descriptors of plants communities (concentration of in‐stream nitrate and percentages of surrounding natural habitat and annual crop land) were assessed. The effects of agriculture on two dominant non‐native grasses species and their effects on species richness were also assessed.ResultsIn total, 274 plant taxa were identified, including 181 taxa in the soil seed bank and 231 taxa in the vegetation. Overall species richness was high in both the soil seed bank and above‐ground vegetation and was unaffected by measures of agricultural intensity (surrounding annual crop land and N enrichment). Above‐ground vegetation species richness was strongly negatively affected by the widespread and dominant non‐native grasses, Phalaris arundinacea and Bromus inermis, whereas soil seed bank species richness was unaffected. The community compositions of both the soil seed bank and vegetation were negatively affected by the loss of natural habitat and by N enrichment. In fact, an increase in the percentage of non‐native species and a decrease in floristic quality were observed along a gradient of agricultural intensity.ConclusionsSpecies richness of the soil seed bank demonstrated resilience to invasions by P. arundinacea and B. inermis, and the soil seed bank showed good potential for conservation of taxonomic diversity. However, the loss of natural habitat and N enrichment had negative effects on the soil seed bank community composition that may lead to an eventual decline in above‐ground species richness.

Where does the community start, and where does it end? Including the seed bank to reassess forest herb layer responses to the environment

AbstractQuestionBelow‐ground processes are key determinants of above‐ground plant population and community dynamics. Still, our understanding of how environmental drivers shape plant communities is mostly based on above‐ground diversity patterns, bypassing below‐ground plant diversity stored in seed banks. As seed banks may shape above‐ground plant communities, we question whether concurrently analysing the above‐ and below‐ground species assemblages may potentially enhance our understanding of community responses to environmental variation.LocationTemperate deciduous forests along a 2000 km latitudinal gradient in NW Europe.MethodsHerb layer, seed bank and local environmental data including soil pH, canopy cover, forest cover continuity and time since last canopy disturbance were collected in 129 temperate deciduous forest plots. We quantified herb layer and seed bank diversity per plot and evaluated how environmental variation structured community diversity in the herb layer, seed bank and the combined herb layer–seed bank community.ResultsSeed banks consistently held more plant species than the herb layer. How local plot diversity was partitioned across the herb layer and seed bank was mediated by environmental variation in drivers serving as proxies of light availability. The herb layer and seed bank contained an ever smaller and ever larger share of local diversity, respectively, as both canopy cover and time since last canopy disturbance decreased. Species richness and β‐diversity of the combined herb layer–seed bank community responded distinctly differently compared to the separate assemblages in response to environmental variation in, e.g. forest cover continuity and canopy cover.ConclusionsThe seed bank is a below‐ground diversity reservoir of the herbaceous forest community, which interacts with the herb layer, although constrained by environmental variation in e.g. light availability. The herb layer and seed bank co‐exist as a single community by means of the so‐called storage effect, resulting in distinct responses to environmental variation not necessarily recorded in the individual herb layer or seed bank assemblages. Thus, concurrently analysing above‐ and below‐ground diversity will improve our ecological understanding of how understorey plant communities respond to environmental variation.

Methodological bias in the seed bank flora holds significant implications for understanding seed bank community functions.

Persistent seed banks are a key plant regeneration strategy, buffering environmental variation to allow population and species persistence. Understanding seed bank functioning within herb layer dynamics is therefore important. However, rather than assessing emergence from the seed bank in herb layer gaps, most studies evaluate the seed bank functioning via a greenhouse census. We hypothesise that greenhouse data may not reflect seed bank-driven emergence in disturbance gaps due to methodological differences. Failure in detecting (specialist) species may then introduce methodological bias into the ecological interpretation of seed bank functions using greenhouse data. The persistent seed bank was surveyed in 40 semi-natural grassland plots across a fragmented landscape, quantifying seedling emergence in both the greenhouse and in disturbance gaps. Given the suspected interpretational bias, we tested whether each census uncovers similar seed bank responses to fragmentation. Seed bank characteristics were similar between censuses. Census type affected seed bank composition, with >25% of species retrieved better by either census type, dependent on functional traits including seed longevity, production and size. Habitat specialists emerged more in disturbance gaps than in the greenhouse, while the opposite was true for ruderal species. Both censuses uncovered fragmentation-induced seed bank patterns. Low surface area sampling, larger depth of sampling and germination conditions cause underrepresentation of the habitat-specialised part of the persistent seed bank flora during greenhouse censuses. Methodological bias introduced in the recorded seed bank data may consequently have significant implications for the ecological interpretation of seed bank community functions based on greenhouse data.

Soil seed bank depletion as a mechanism of Lantana camara L. invasion

Lantana camara is an invasive plant in South Africa with a wide range of impacts. This study assessed the impact of L. camara invasion on the soil seed bank. The study asked the question, does species density and diversity of soil seed banks differ between L. camara invaded and uninvaded sites? The study was conducted over a 10-month period under greenhouse conditions using soils collected from five L. camara invaded and uninvaded sites that were located between Port Alfred and East London in the Eastern Cape province of South Africa. The study measured species density, diversity and identified seedlings that germinated in trays containing soils from invaded and uninvaded sites. Species density and diversity were lower in L. camara invaded sites compared with uninvaded sites, an indication that L. camara invasion has the potential to deplete the soil seed bank of other species. The study concluded that L. camara invasion reduces the soil seed bank community composition and structure.

Weed Seedbank Characterization in Long‐Term Cotton–Tomato Rotations in California

This article characterizes the weed seedbank after a 12‐yr rotation of cotton (Gossypium hirsutum L.)–tomato (Lycopersicon esculentum L.) under standard tillage (ST) and conservation tillage (CT) with and without cover crops in Five Points, CA, from 1999 to 2011. Treatment comparisons included standard tillage with no cover crop (STNO), standard tillage with cover crop (STCC), conservation tillage with no cover crop (CTNO), and conservation tillage with cover crop (CTCC). Weed density, by species, in each plot was assessed in 2003, 2006, and 2011. In 2011, soil cores were taken from each plot and seedlings that emerged from these cores were monitored in the greenhouse, counted by species, and the data were subjected to canonical discriminant analysis. Differences in weed densities were not consistent between CT and ST plots but they were generally greater in plots with cover crops than in those without, particularly in the CT system. The seedbank size was largest in the CTCC system. The weed seedbank community composition of this system was also distinctly different from the other systems. Shepherd's‐purse (Capsella bursa‐pastoris L. Medik.), black nightshade (Solanum nigrum L.), henbit (Lamium amplexicaule L.), and common chickweed (Stellaria media L. Vill.) were associated with the CTCC system. Barnyardgrass (Echinochloa crus‐galli L. Beauv.) and horseweed (Conyza canadensis L. Cronq.) were associated with the CTNO system. Although differences in the aboveground weed densities were inconsistent between the tillage systems, the weed seedbank size was greater in the CT system and having a cover crop further increased the seedbank size.

Invasion by Solidago species has limited impacts on soil seed bank communities

Increasing attention in invasion biology is being paid to measuring and understanding the impacts of invasive species. For plant invasions, however, the impact of invasion on soil seed bank communities has been under-studied. At six sites in southern Germany, we investigated whether areas invaded by Solidago gigantea and Solidago canadensis experienced a reduction in seed bank species richness, size and diversity, and a change in species composition compared to adjacent uninvaded areas. We found no overall effect of invasion on seed bank size, or on species richness and diversity. Seed bank size significantly decreased from 0–5cm to 5–10cm depth in both invaded and uninvaded areas. A significant amount of variation in species composition was explained by invasion, but it was only one-tenth of that explained solely by site effects. Our study suggests that invasion by Solidago species may not have the same impacts on the soil seed banks of native species as other invasive perennial forbs that have so far been studied.

Weed seed-bank responses to long-term fertilization in a rice-wheat rotation system

We studied the heterogeneity of soil weed seed-bank in a rice-wheat rotation system after long-term application of different organic or non-organic fertilizers, and the effects of major nutrients on the characteristics of the weed seed-bank. The soil was sampled in the Taihu area after a 31-year long-term fertilization experiment. Weed seeds were identified and counted in the surface soil of 12 differentially treated areas using microscopic examination, and analyzed by the Simpson, Shannon, Margalef, and Pielou indexes. The long-term application of organic fertilizers could significantly reduce the density of soil weed seed-bank; non-organic fertilizers and a combination of non-organic and organic fertilizers had a significant influence on the number of species and diversity of weeds. The application of organic fertilizers improved the Simpson, Shannon and Pielou indexes of soil weed seed-bank community and stabilized the community structure. In terms of the soil nutrient system itself, the soil organic materials and total nitrogen content are the main environmental factors affecting the distribution of soil weed seed-bank.

Assessing wetland mitigation efforts using standing vegetation and seed bank community structure in neighboring natural and compensatory wetlands in north-central Texas

It is often presumed plant recruitment from the soil seed bank and nearby wetlands will be sufficient to establish a wetland plant community following the restoration or creation of wetland hydrology. This approach to wetland restoration was examined in four compensatory wetlands and a natural oxbow wetland (Oxbow) in a floodplain of the West Fork Trinity River in north-central Texas. We assessed: (1) similarities in vegetation and seed bank composition among natural and compensatory wetlands, (2) within site similarity of vegetation relative to its seed bank community, and (3) the effects of hydrology (Wet vs. Drained soil) on the germination of seeds from the seed bank. Species richness of the standing vegetation was variable across sites and years, however when pooled across years (2008–2009) vegetation and seed banks showed similar species richness (66 vs. 70 species). Fewer wetland species (i.e., species occurring in wetlands >50 % of the time) were observed in the vegetation relative to the seed bank (25 vs. 41 species), and seed banks of compensatory wetlands were more similar to the natural wetland than was the standing vegetation. In the seed bank study, location (i.e., site) significantly affected total species richness, wetland species richness, diversity, and germinated seeds m−2, however no significant effect of hydrology was detected. These results suggest hydrology alone is not sufficient to establish a desired wetland plant community in a created wetland and the inclusion of seed bank surveys with field vegetation surveys provides a more complete assessment of wetland creation and restoration.

Changes in the species and functional trait composition of the seed bank during semi‐natural grassland assembly: seed bank disassembly or ecological palimpsest?

AbstractQuestionUnlike above‐ground plant community assembly, the processes that govern assembly of the soil seed bank following severe habitat disturbance are poorly understood. Two hypotheses have been put forward in this context: (1) the ‘ecological palimpsest hypothesis’ assumes a gradual accumulation of species in the seed bank; and (2) the ‘community disassembly hypothesis’ assumes a gradual deterministic loss of species from the seed bank. Here, we investigated which hypothesis is applicable to the seed bank assembly of semi‐natural grasslands, following forest clearance. Furthermore, we asked whether seed bank community divergence occurred at the species and at the functional trait level.LocationRestored and ancient (old) calcareous grasslands in south Belgium.MethodsThe species composition of 106 seed bank samples from three restoration age classes were obtained through a germination experiment. Community‐weighted means were calculated for 26 functional traits. We evaluated changes in species and functional composition with increasing grassland age. Differentiation in species and trait composition was compared between age groups. Finally, we tested for the occurrence of nestedness of the seed bank communities according to age.ResultsSeed bank species richness decreased with time since restoration, at the trait level reflected by the replacement of traits associated with generalist therophytes by traits typical for chamaephytes and grassland specialists. Whereas species differentiation remained relatively constant, trait differentiation decreased with time since restoration. The seed bank composition of old grasslands was a nested subset of that of young grasslands.ConclusionsOur results suggest that the ‘community disassembly hypothesis’ is applicable to the community assembly of semi‐natural grasslands. Directly following forest clearance, a diverse seed bank is formed, followed by a gradual net loss of species. Surprisingly, this species loss is not governed by seed persistence traits but by functional changes in the above‐ground community. This disassembly process results in one deterministic end state at the trait level, but not at the species level.

Soil seed bank community structure of pastures and hayfields on an organic farm

Sanderson, M. A., Stout, R., Goslee, S., Gonet, J. and Smith, R. G. 2014. Soil seed bank community structure of pastures and hayfields on an organic farm. Can. J. Plant Sci. 94: 621–631. Understanding the composition of seed banks in pasture soils would help farmers anticipate and manage for weed problems. We characterized the soil seed bank in eight pastures and hayfields [two alfalfa (Medicago sativa L.) and two predominantly grass hayfields; two recently established and two permanent pastures] within an organic dairy farm in southeastern New Hampshire. Seed banks were sampled in the upper 5 cm of soil in each field at a point scale in 2007 and 2010. In 2010, the seed bank was characterized at the field scale by taking soil samples on six 52-m transects in each field. Seed banks sampled at the field scale in 2010 contained 66 plant species. The total number of seeds in the seed bank ranged from 1560 m−2 in grass hayfields in autumn to more than 20 000 m−2 in alfalfa hayfields in summer. Annual forbs dominated the seed bank of alfalfa fields and recently established pastures, whereas perennial graminoids dominated in one grass hayfield and the permanent pastures. These results suggest that management history affects soil seed bank composition and abundance, and these effects should be considered before implementing management practices that could stimulate recruitment from the seed bank.

Impact of invasions by alien plants on soil seed bank communities: Emerging patterns

Much of our current understanding of the impact of invasive species on plant communities is based on patterns occurring in the above-ground vegetation, while only few studies have examined changes in soil seed banks associated with plant invasions, despite their important role as determinants of vegetation dynamics. Here, we reviewed the literature on the impact of plant invasions on the seed bank and we provide a quantitative synthesis using a meta-analysis approach. Specifically, (1) we quantified the impact of 18 invasive alien plants on (i) species richness and (ii) density of the seed banks of invaded communities, based on 58 pair-wise invaded-uninvaded comparisons (cases); we identified (2) the invasive taxa that are responsible for the largest changes in the seed bank; and (3) the habitats where substantial changes occur. Our study showed three major findings: (1) species richness (68% of cases) and density (58% of cases) were significantly lower in native seed banks invaded by alien plants; (2) species richness and density of native and alien species were remarkably lower in seed banks invaded by large, perennial herbs compared to uninvaded sites; and (3) invaded seed banks were often associated with a larger richness and/or abundance of alien species. This study indicates a need for additional seed bank data in invasion ecology to characterize species-specific and habitat-specific impacts of plant invasions, and to determine whether changes in the seed banks of native and alien species are a symptom of environmental degradation prior to a plant invasion or whether they are its direct result. The findings of this study help improve our capacity to predict the long-term implications of plant invasions, including limitations in the recruitment of native species from the seed bank and the potential for secondary invasions by seeds of other alien species.

Warming increases plant biomass and reduces diversity across continents, latitudes, and species migration scenarios in experimental wetland communities

Atmospheric warming may influence plant productivity and diversity and induce poleward migration of species, altering communities across latitudes. Complicating the picture is that communities from different continents deviate in evolutionary histories, which may modify responses to warming and migration. We used experimental wetland plant communities grown from seed banks as model systems to determine whether effects of warming on biomass production and species richness are consistent across continents, latitudes, and migration scenarios. We collected soil samples from each of three tidal freshwater marshes in estuaries at three latitudes (north, middle, south) on the Atlantic coasts of Europe and North America. In one experiment, we exposed soil seed bank communities from each latitude and continent to ambient and elevated (+2.8°C) temperatures in the greenhouse. In a second experiment, soil samples were mixed either within each estuary (limited migration) or among estuaries from different latitudes in each continent (complete migration). Seed bank communities of these migration scenarios were also exposed to ambient and elevated temperatures and contrasted with a no-migration treatment. In the first experiment, warming overall increased biomass (+16%) and decreased species richness (-14%) across latitudes in Europe and North America. Species richness and evenness of south-latitude communities were less affected by warming than those of middle and north latitudes. In the second experiment, warming also stimulated biomass and lowered species richness. In addition, complete migration led to increased species richness (+60% in North America,+100% in Europe), but this higher diversity did not translate into increased biomass. Species responded idiosyncratically to warming, but Lythrum salicaria and Bidens sp. increased significantly in response to warming in both continents. These results reveal for the first time consistent impacts of warming on biomass and species richness for temperate wetland plant communities across continents, latitudes, and migration scenarios.

Seed bank and its restoration potential in Estonian flooded meadows

AbstractQuestionsWhat is the overall restoration potential of the persistent soil seed bank of abandoned flooded meadows? To what degree does the share of typical flooded meadow species in the soil seed bank change during secondary succession from traditionally managed hayfields to stages overgrown by woody vegetation?LocationFlooded meadows in Alam‐Pedja Nature Reserve, central Estonia (26°14′ E, 58°33′ N).MethodsThe species composition of above‐ground vegetation and the persistent soil seed bank were investigated with PerMANOVA and non‐metric multidimensional scaling in mown, 25‐yr abandoned and 50‐yr abandoned sedge and tall forb meadows subjected to annual flooding. Particular attention was given to typical flooded meadow species in the persistent soil seed bank. General linear models and non‐parametric tests were used to assess successional trends in seed bank richness, density, similarity to target vegetation and percentage of flooded meadow species to assess the restoration potential of the soil seed bank.ResultsThe cessation of traditional management has led to considerable changes in both above‐ground and seed bank communities, differences between successional stages being more pronounced in the soil seed bank. The density of the seed bank was higher in abandoned meadows. Diversity in the vegetation and soil seed bank was lowest in the 25‐yr abandoned tall forb meadows. Although the soil seed bank similarity to above‐ground mown meadows (locally defined target vegetation) was relatively low across different successional stages, the proportion of flooded meadow species in the seed bank remained high – even after 50‐yr abandonment, on average 42% of emerged seeds from sedge meadow and 34% from tall forb meadow were typical flooded meadow species.ConclusionsAbandoned floodplain meadows in central Estonia still contain a relatively large grassland community species pool, including a large and effective soil seed bank. The soil seed bank could thus play an important role in the restoration of abandoned and overgrown meadow communities. Targeted experiments addressing the optimal techniques for activating the soil seed bank in flooded meadow soil are needed.

Effects of sediment removal on vegetation communities in Rainwater Basin playa wetlands

Sedimentation from cultivated agricultural land use has altered the natural hydrologic regimes of depressional wetlands in the Great Plains. These alterations can negatively affect native wetland plant communities. Our objective was to determine if restored wetlands are developing plant communities similar to reference wetland conditions following hydrologic restoration. For this study, hydrology was restored via sediment removal. Thirty-four playa wetlands in reference, restored, and agricultural condition within the Rainwater Basin Region of Nebraska were sampled in 2008 and 2009. In 2008, reference and restored wetlands had higher species richness and more native, annual, and perennial species than agricultural wetlands. Restored wetlands had similar exotic species richness compared to reference and agricultural wetlands; however, reference wetlands contained more than agricultural wetlands. Restored wetlands proportion of exotics was 3.5 and 2 times less than agricultural wetlands and reference wetlands respectively. In 2009, reference and restored wetlands had higher species richness, more perennial species, and more native species than agricultural wetlands. Restored wetlands contained a greater number and proportion of annuals than reference and agricultural wetlands. Canonical Correspondence Analysis showed that reference, restored, and agricultural wetlands are dominated by different plant species and guilds. Restored wetland plant communities do not appear to be acting as intermediates between reference and agricultural wetland conditions or on a trajectory to reach reference conditions. This may be attributed to differing seed bank communities between reference and restored wetlands, dispersal limitations of perennial plant guilds associated with reference wetland conditions, and/or management activities may be preventing restored wetlands from reaching reference status.