Patterns of seed persistence in South African fynbos

In fire-prone communities such as fynbos, many species rely on regeneration from seed banks in the soil. Persistent seed banks are particularly important for species with life spans shorter than the average fire cycle, in order to counter local extinction. Persistent seed banks also give potential for restoring ecosystems following disturbances such as alien plant invasion. This study investigated the seed persistence patterns of 25 perennial species, representing several growth forms and life histories, during a three-year burial. Long-term persistence (i.e., seed bank half-life exceeding two years) was found in the hard-seeded Fabaceae and Pelargonium, and the nut-fruited Proteaceae. In this group, germinability was low and dormancy increased further following burial, resulting in a highly viable, dormant seed bank after three-year's burial. A second group with potentially long-term persistent seeds includes four taxa (Pseudopentameris, Passerina, Elegia and Restio) that either have low germinability or develop secondary dormancy following burial. Dormancy in the latter group was partially countered by exposure to smoke-seed primer. Of the small-seeded species, only two Erica species with high initial dormancy had long-term persistent seed banks. The other species mostly displayed high initial germinability and short-term persistent seed banks (i.e., seed bank half-life less than two years). This group included taxa with short to medium life-spans (Syncarpha, Roella) that were expected to have long-term persistent seeds in order to buffer against local extinction following average to long fire-return intervals. We hypothesize that light may play a role in overcoming secondary dormancy in those species, and could have resulted in an underestimate for seed persistence in this study. Alternatively, those short to medium life-span species persist via inter-fire recruitment in gaps or long-distance dispersal (of the smallest seed). No correlations were found between seed persistence and seed mass or variance in seed dimensions. Nor was a correlation found between seed persistence and phenol concentration. In fynbos, seed burial of larger seeds by ants and rodents are major processes that operate in conjunction with passive burial of small seeds. Selection for persistence can be expected to operate across all seed sizes and shapes in fire-prone communities.     

Alpine species seed longevity in the soil in relation to seed size and shape – A 5-year burial experiment in the Central Alps

Long-term persistent seeds are generally expected to be small and spherically shaped. In contrast, transient seeds are often large, flattened and elongated. We hypothesized that alpine species follow these trends, and that most species of unstable alpine habitats have the potential to form long-term persistent seed banks. The latter would enable them to delay germination until favourable conditions are present in their environment thereby increasing the likelihood for establishment of seedlings. We selected nine alpine species of more or less unstable habitats (i.e. Achillea moschata, Artemisia genipi, Anthyllis vulneraria ssp. alpicola, Geum reptans, Linaria alpina, Oxyria digyna, Saxifraga aizoides, Saxifraga oppositifolia, and Trifolium pallescens) for this study. Seed longevity was estimated by a 5-year burial experiment in the field with seed excavations after 1 winter, 2 years and 5 years. Germination experiments in the growth chamber and viability tests were performed after each excavation. We detected longevity patterns ranging from transient to long-term persistent. Two species were classified as transient. All other species have the potential to form persistent seed banks, with almost half of the investigated species showing a trend for long-term persistence. Despite contradictory reports, long-term persistent seed banks are an important life history trait of species of unstable alpine habitats. We found that seed shape and hard-seededness are good predictors of seed persistence of alpine species. Seed size seems to be less important. The data from this study support the general hypotheses describing the relationship among seed size, seed shape and seed persistence in the soil.     

Assessing the impact of plant invasions on soil seed bank communities: use of univariate and multivariate statistical approaches

Questions: Are soil seed banks affected by invasions of alien plants? How can we rigorously assess alterations in seed bank communities associated with invasive species and account for the high spatial variability of seed bank data? How do multivariate approaches compare with more traditional approaches based on analysis of variance? Location: Three riparian sites, Ireland. Methods: A protocol based on a combination of multivariate techniques was used to characterize soil seed bank communities associated with the herbaceous invasive species Heracleum mantegazzianum in May and October. Permutational multivariate analysis of variance (PERMANOVA) was used to test the effects of the factors “invasion”, “site”, “plot” and “depth” on the soil seed bank, while multivariate analysis of dispersion (PERMDISP) provided a measure of the variability of seed bank data at different spatial scales. Similarity percentages analysis (SIMPER) was used to identify the species that contributed most to the differences between invaded and uninvaded communities. A comparison between the results of PERMANOVA and ANOVA analyses was also made. Results: The composition of seed bank communities invaded by H. mantegazzianum differed significantly from that of uninvaded seed banks. Invaded seed banks were less diverse and had reduced abundance, and were dominated by only a few species, such as Urtica dioica and Juncus effusus. Such patterns were recorded at each of three depth categories, indicating that invasive plants can affect both the transient and the more persistent component of the soil seed bank. Seed bank variability was significantly higher within uninvaded areas, supporting the notion that invasions tend to lead to more homogeneous communities. Conclusion: The analytical protocol used in this study was effective in quantifying the effect of plant invasions, at different spatial scales, providing a statistically robust analysis of alterations in soil seed bank communities. Compared to ANOVA, this protocol provided more biological information and was more appropriate for analysis of the data. This approach is therefore recommended in soil seed bank and invasion ecological studies.     

Do seed harvesting ants threaten the viability of a critically endangered non-myrmecochorous perennial plant population? A complex interaction

This study analyzes the fate of seeds removed by ants, as well as the seed supply, seedling survival, and the ability to form persistent seed banks in the soil, in a critically endangered population of the non-myrmecochorous perennial halophyte Helianthemum polygonoides, in order to determine the extent to which seed removal by ants represents a real bottleneck for recruitment and thus a threat for long-term population viability. Apparently, the impact of seed-harvester ants was dramatic: the primary seed shadow was reduced by up to 93% by the activity of Messor bouvieri and Aphaenogaster dulcineae. However, M. bouvieri lost 7% of fruits collected by dropping them on trunk trails, mostly under plant cover, the most propitious microenvironment for recruitment. In addition, some seeds were mistakenly rejected in refuse piles, although here recruitment was extremely low. A significant fraction of seeds (≈40%) remained viable in the soil for over 2 years. In addition, H. polygonoides had the ability to form short-term persistent seed banks, in spite of the intense ant seed removal. In general, seedling recruitment was very low, denoting the scarcity of safe sites in the habitat. Overall, the data corroborate that seed removal by ants, although highly intense, does not compromise the viability of perennial-plant populations, because seed supply and seed reserve in the soil are enough to exploit current and future safe sites. A population viability analysis demonstrated that other threats affecting the survival of reproductive H. polygonoides plants actually constitute the real risk for the conservation of this critically endangered species.     

Relationships among the seed rain,seed bank and vegetation of a Hawaiian forest

Abstract. Hawaiian ecosystems are prone to invasion by alien plant species. I compared the seed rain, seed bank, and vegetation of a native Hawaiian forest to examine the potential role that seed ecology plays in allowing alien species to invade native forest. Absolute cover of seed plants in the forest was 126 %, annual seed rain was 5 713 seeds m^-2 yr^-1, and the mean density of seedlings emerging from the seed bank averaged across four seasons was 1 020/m². The endemic tree Metrosideros polymorpha was the most abundant species in the vegetation, seed rain and winter seed bank. Overall, native seed plants comprised 95 % of the relative cover in the vegetation and 99 % of the seeds in the seed rain, but alien species comprised 67 % of the seeds in the seed bank. Alien species tended to form persistent seed banks while native species formed transient or pseudo-persistent seed banks. Dominance of the seed bank by alien species with persistent seed banks suggests that aliens are favorably placed to increase in abundance in the vegetation if the forest is disturbed.     

Restoration prospects of abandoned species‐rich sandy grassland in Hungary

Abstract. Secondary succession and seed bank formation was studied in a formerly grazed, abandoned, eastern Hungarian sandy steppe‐meadow (Pulsatillo‐Festucetum). The vegetation was sampled at different elevations of a sand dune which became partly invaded by the tree Robinia pseudo‐acacia ca. 10 yr ago. Pre‐abandonment vegetation records were used as historic references. Though composition of the non‐invaded grassland only changed moderately, dominance of tall grasses (Elymus hispidus, Poa angustifolia) increased significantly at the cost of annuals and low stature perennials. In the stand invaded by Robinia most grassland species were lost and replaced by nitrophytes. Vertical position influenced species abundance, but affected the composition only moderately. Fine‐scale zonation of the vegetation also changed with time. Species richness of the above‐ground vegetation and the seed density of soil samples at the lower elevation were slightly greater than at the higher sites. Seed banks of sensitive grassland specialists (e.g. Pulsatilla pratensis subsp. hungarica) disappeared during grass encroachment. Following extinction from above‐ground vegetation, restoration must rely on dispersal from adjacent areas. In contrast, several annuals and perennials, which survived this degradation stage in the above‐ground vegetation, possessed seed banks. Many of these species became extinct from the vegetation during the Robinia invasion but left viable persistent seeds. This fact is promising for restoration of the Potentillo‐Festucetum sandy pasture. Competitive weedy species and sprouting Robinia can, however, limit seedling establishment.     

Similarities in the impact of three large invasive plant species on soil seed bank communities

Invasions by alien plant species may substantially alter soil seed bank communities. While decreases in seed bank species richness, diversity, and composition as a consequence of plant invasions have been reported, the characteristics of seed banks associated with different invasive species have not been compared in any detail. Here, we describe changes in the characteristics of soil seed banks invaded by three large herbaceous invasive plants, Fallopia japonica, Gunnera tinctoria, and Heracleum mantegazzianum. The study was carried out at the spatial scales of site and plot, to reduce variability in seed bank data. Information on seed bank persistence was inferred from seed depth (0–5, 5–10, and 10–15 cm) and from time of sampling (May and October). Despite differences in the reproductive strategy and geographic distribution of these invaders, as well as in the standing vegetation and habitat types examined, the seed banks of invaded areas were similar in composition and in the relative abundance of different species. Invaded seed banks were dominated by seeds of a few agricultural weed species and/or rushes, suggesting that common features of the invaders, including a large standing biomass, extensive litter production, and the formation of mono-species stands may result in comparable selection pressures that favors traits that are largely genera or species-specific. These findings have a direct relevance for the development of strategies aimed at restoring previously-invaded sites while also improving our understanding of the long-term implications of plant invasions.     

兰坪铅锌矿区植被恢复初期土壤种子库与地上植被关系的研究

尾矿废弃地是一种极端的生态系统,其植被恢复的研究将丰富传统的生态学理论。该研究通过野外植被调查与室内萌发实验相结合的方法,探讨了兰坪铅锌矿区植被恢复初期不同群落类型地上植被、土壤种子库及其相互关系。结果显示:（1）与对照群落（云南松林、高山栎灌丛）相比,尾矿区恢复期各群落（早熟禾人工草地、魁蒿群落、马桑灌丛）地上植被及土壤种子库的物种数、物种多样性均较低。（2）植被恢复时间较短的2个群落（魁蒿群落、人工草地）土壤种子库较地上植被物种多样性高。（3）尾矿区恢复期各群落地上植被及土壤种子库的优势种均主要由风播、种子繁殖的植物组成,菊科、禾本科占较大比例,这些植物在尾矿区植被恢复初期起重要作用。（4）尾矿区恢复期各群落土壤种子库与地上植被的物种相似性较高,各群落之间地上植被及土壤种子库的相似性则较低。研究表明,尾矿区恢复初期土壤种子库与地上植被紧密联系,群落改造方式、恢复时间对土壤种子库具有重要影响。     

The role of the soil seed bank in vegetation recovery on an oceanic island severely damaged by introduced goats

Question: Are the seed banks of an isolated subtropical oceanic island capable of naturally regenerating vegetation either with species of the historical forest community or with the existing grassland community after severe damage to the vegetation by goats? Location: Nakoudojima Island, Bonin Archipelago (Ogasawara Shoto), Japan. Methods: Soil samples were collected at 0–5 cm and 5–10 cm depths from seven plots in forests, grasslands, artificially matted areas and bare land. Soil seed banks were assessed using the seedling emergence method followed by the hand‐sorting of ungerminated seeds. We determined the size and composition of the seed banks in upper soil layers of plots and compared the seed banks to the standing vegetation. Results: A total of 12 220 seedlings belonging to 42 species from 20 families germinated. Total mean seed density (0–5 cm depth) was low in all plots within forest, grassland, and heavily degraded vegetation types (34.7 ± 8.6 to 693.5 ± 123.6, 58.6 ± 7.8 to 107.1 ± 10.0, and 1.1 ± 0.5 to 7.2 ± 2.3 seeds/m², respectively). Forbs and graminoids dominated the seed banks of grassland and forest plots including Cyperus brevifolius, Gnaphalium pensylvanicum, Oxalis corniculata and Solanum nigrum, and these alien species comprised 90% of the density of the seed bank. There was little correlation between seed banks and standing vegetation of the island (Sørensen similarity coefficient values 0.26 to 0.45). Conclusions: If natural regeneration occurs from the seed bank of the island, future vegetation will not move toward the original forest community, because the seed bank is dominated by non‐native herbaceous grassland species. Though isolated, a few forest remnants with low species richness could be an important source for the natural re‐establishment of forest on the island; however, seed availability may be limited by either poor dispersal or pollination so that woody species will probably recover very slowly on this goat‐impacted island.     

Seed Bank and Vegetation Development of Sandy Grasslands After Goose Breeding

Four hypotheses were tested using long-term observations of vegetation development (12 years) and present-day seed bank data in a sandy grassland area overgrazed by domestic geese: i) Gap regeneration is crucial in maintaining species richness; thus, closed vegetation of the lower sites prevents continuous establishment of short-lived species. ii) Short-lived, early successional species comprise most of the seed banks and late successional perennials have at most sparse seed banks. iii) Composition of seed banks is more similar to pioneer vegetation than to later successional stages. iv) The similarity is higher between vegetation and seed banks in the upper-positioned plots than in the closed, lower-positioned ones. Two sites, located in the upper part of dune slopes, and another two, positioned on the lower part, were studied. In each site five 2?×?2 m permanent plots were surveyed between 1991 and 2002. Percentage cover was estimated three times a year. In the last study year, soil seed banks were sampled. Two vertical segments (0–5, 5–10 cm) were separately analyzed. The seedling emergence method was applied on concentrated samples. We found that the vegetation developed from open, annual dominated weedy assemblages to grasslands dominated by perennial graminoids. In the lower-positioned sites perennial clonal grasses (Cynodon dactylon, Poa angustifolia and P. pratensis) formed more closed vegetation, which was accompanied by lower species richness compared to the upper-positioned sites. Seed density varied between 10,300 and 40,900 seeds/m². Significantly higher seed densities were found in upper sites than in the lower ones. Annuals and short-lived perennial dicots comprised most of the seed bank. The dominant perennial graminoids also built up dense seed banks. We found a low to medium similarity between vegetation and the seed bank; similarity was the highest with the vegetation of the 1994–1998 period. In the upper sites the similarity between seed bank and the vegetation of the last studied years was also high. The vertical position had a significant effect on regeneration after overgrazing. The large cover of grasses in lower sites decreased species richness and it also decreased the seed density preventing the seed bank formation of annuals and short-lived perennials. Here, further management practices are needed to increase the species richness.     

Species Recruitment following Flooding,Sediment Deposition and Seed Addition in Restored Riparian Areas

In recent years an increasing number of streams have been restored to improve conditions for natural fen and meadow vegetation to develop in the associated riparian areas, but with modest success. Here we apply a controlled and replicated approach to investigate the role of flooding, sediment deposition, and seed addition for species recruitment in riparian areas with different types of standing vegetation. We expect that species recruitment is restricted in areas where the vegetation is dominated by fast‐growing productive species because competition for light will make the establishment of new species difficult, especially for low‐productive target species. We found that the naturally recruited species were few, mostly common, and widely distributed species. A majority of the recruited species, including target species added as seeds into the sediments, emerged in all areas independent of the characteristics of the standing vegetation. We observed significant temporal changes in compositional patterns throughout the experimental period (May to October). These changes were especially pronounced in areas with fen/fen‐meadow vegetation and were closely associated with the emergence and growth of species originating from the deposited sediments (e.g. Equisetum pratense, Poa trivialis, Urtica dioica), including the seeded target species (Lychnis flos‐cuculi and Lotus pedunculatus) and with a decline in fen‐associated mosses and small sedges. Compositional changes were also associated with shifts toward more productive species in areas previously dominated by low and intermediately productive species. We infer that flooding and sediment deposition play a limited role for recruitment of target species in riparian areas and that sediment deposition may entail a risk of losing diversity in riparian areas.     

Weed seed banks in arable fields under contrasting pesticide regimes

Viable weed seed banks on a clay soil were estimated for five years from 11 arable fields receiving one of three levels of pesticide application. Low seed densities, averaging 2000 m^-2, were recorded, but dicotyledonous weed seed numbers usually increased following oilseed rape crops, reaching 26 000 m^-2 in one field. Field-to-field variability was large. Samples could be grouped using multivariate techniques into those dominated by grass weed seeds and those containing mainly dicotyledonous weed seeds. Within TWINSPAN classifications, most fields maintained similar seed banks during the study period, indicating relative stability of communities. Differences present at the outset of the experiment, including variation between fields in the same treatment area, were maintained for the five years. Patterns were not associated with straw disposal or spring herbicide application. Oilseed rape crops did not cause qualitative change in seed bank communities, but allowed certain species, notably Stellaria media and Sonchus asper, to increase seed numbers. Smaller and less diverse seed banks in the area receiving most herbicide were not statistically significant. Seed banks gave poor predictions of following weed populations.     

Spatial patterns in seed bank and vegetation of semi-natural mountain meadows

Soil seed bank composition and vegetative spatial patterns were studied in four mountain meadow communities in the Broto Valley (N. Spain), in order to analyse the differences that might exists between the two life forms. Soil and vegetation samples were taken at 1 m intervals from 10 m × 10 m quadrats in each meadow in one-year study. The spatial distribution of species was analysed along with the calculation of an autocorrelation coefficient which takes account of the relative position of samples: (Moran’s I). The results indicate that the abundance of the majority of the species in the seed bank and in the vegetation are randomly distributed, the percentage of species with a clumped distribution only exceeds 35% in the vegetation of one meadow and none of the taxa identified showed a uniform spatial organisation. The species that were distributed in the seed bank in a clumped pattern in more than one meadow were those of the pioneer species (Anagallis arvensis, Centaurium erythraea, Lamium purpureum and Stellaria media). All of these formed long-term persistent seed banks but were absent in the established vegetation in these meadows. According to the results, there exist not only differences between the spatial distribution of the species present in the same community, but also, that some species change their pattern of distribution according to the life form and to the grassland type in which they are found.     

Indirect interactions between browsers and seed predators affect the seed bank dynamics of a chaparral shrub

Interactions between herbivores and seed predators may have long-term consequences for plant populations that rely on persistent seed banks for recovery after unpredictable fires. We assessed the effects of browsing by deer and seed predation by rodents, ants and birds on the densities of seeds entering the seed bank of Ceanothus cuneatus var. rigidus, a maritime chaparral shrub in coastal California. Ceanothus produced many more seeds when protected from browsers in long-term experimental exclosures than did browsed plants, but the seed densities in the soil beneath browsed and unbrowsed Ceanothus were the same at the start of an intensive one-year study. The density of seeds in the soil initially increased in both treatments following summer seed drop: while densities returned to pre-drop levels within a few weeks under browsed plants, soil seed densities remained high for 5–8 months beneath unbrowsed plants. Rodent abundance (especially deer mice) was higher near unbrowsed plants than >30 m away, and rodents removed Ceanothus seeds from dishes in the experimental plots. At least in the short term, rodent density and rates of seed removal were inversely related to the intensity of browsing. Our data have management implications for maintaining viable Ceanothus populations by regulating the intensity of browsing and the timing, intensity and frequency of fires.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at .     

Persistent soil seed bank and standing vegetation at a high alpine site in the central Chilean Andes

The persistent soil seed bank (viable seeds >1 year) and standing vegetation were investigated in the upper alpine belt (3250 m) in the Andes of central Chile, 33° S. Nine species (eight in standing vegetation) were found in a total persistent seed bank of 899 seeds m⁻². Seven additional species were represented by physically intact, non-viable seeds. Over 90% of the persistent seed bank was concentrated in Montiopsis sericea (Portulacaceae), Pozoa coriacea (Umbelliferae), Phacelia secunda (Hydrophyllaceae) and Oxalis compacta (Oxalidaceae). Examination of the seed/cover ratio revealed different propensities for persistent seed bank formation among species, and annuals formed persistent seed banks more frequently than perennial species. Abundance in the standing vegetation had predictive value for abundance in the persistent seed bank only when non-persistent seed bank species in the standing vegetation were discarded from the analysis. At the local scale, species diversity in the persistent seed bank and standing vegetation were correlated, but compositional similarity was low. Secondary down-slope dispersal promoted by frost heaving in combination with runoff, and life-form correlates are discussed as possible factors accounting for poor correspondence between the persistent seed bank and the standing vegetation at a local scale. The high Andean seed bank is similar to or larger than that reported for two Arctic tundra sites, but smaller than for a northern hemisphere subalpine site. If seed bank size is considered in relation to plant cover, the Andean seed bank greatly exceeds that of one Arctic site. Our study constitutes the first demonstration of a sizable persistent seed bank at an alpine site in the South American Andes and in southern hemisphere temperate mountains in general. Received: 26 May 1998 / Accepted: 21 November 1998     

Shrub invasion into subalpine vegetation: implications for restoration of the native ecosystem

The ability of plant communities to recover after non-native species invasion will depend upon the nature of their soil seed bank and seed rain characteristics. This study assessed changes in the soil seed bank and seed rain associated with the invasion of the non-native shrub Cytisus scoparius in subalpine vegetation. Soil seed bank and seed rain composition, density and richness were investigated at three areas of different stages of invasion: (i) recent (8–10 years), (ii) mature (15–16 years) and (iii) long-term (25 years). There were few changes in seed bank composition or richness regardless of invasion stage. By contrast, the seed rain composition, richness and density was substantially different within long-invaded areas. Very few seeds were able to colonise the dense barrier characteristic of larger, more mature C. scoparius stands. Some prominent herbs from the native vegetation were under-represented or absent from the seed bank, both in invaded and uninvaded areas. Laboratory germination experiments demonstrated that most native species germinate easily, which may imply a transient seed bank, rather than a persistent one. The majority of herbaceous and shrub species were capable of resprouting vegetatively. Therefore, regeneration appeared more reliant on the bud and tuber bank than a persistent soil seed bank. The dominance of graminoid species and C. scoparius rather than other herbaceous, shrub or tree species suggests that the regenerating vegetation will be dominated by grass species and/or C. scoparius. Hence, in areas where long-invaded C.␣scoparius stands are present the recovery of native subalpine vegetation maybe difficult. Recovery may only be possible through wind dispersal from the surrounding intact vegetation or through actively reseeding the area. This study highlights the importance of early intervention in invasive species management.     

Seed bank persistence of clonal weeds in contrasting habitats: implications for control

The ability of weeds to form a seed bank is important for their population dynamics and management because it provides a refuge enabling reinvasion after established target plants have died. However, knowledge of the differential seed behaviour of individual species over multiple years and varying environmental conditions is surprisingly rare but necessary for effective control of diverse weed populations. We established a seed burial experiment in alpine habitats differing in management regime (i.e., forest, hay meadow and pasture) to determine whether seeds of the unpalatable perennial weeds, Veratrum album (white hellebore) and Gentiana lutea (yellow gentian) were able to delay germination and remain viable over 3 years. Our study shows that both species formed a short-term persistent seed bank; in the third-year, the soil seed banks of both species were nearly depleted, having declined to <5% of their original size. Both species had strikingly different germination strategies: G. lutea seeds mainly germinated in their first-year, whilst the majority of V. album seeds germinated in their second-year. The fraction of dormant G. lutea seeds increased with seed age, indicating that seeds remained viable after forgoing germination in the previous year. Habitat-specific differences in seed germination increased with seed age, with germination fractions being lowest in moist hay meadows. This suggests that the negative effects of anoxic conditions became more pronounced as seeds aged in hay meadows. Conversely, seed dormancy was equal among habitats. The absence of a long-term persistent seed bank has important implications for the management of both nuisance and endangered-plant populations. In the case of V. album and G. lutea, re-colonization of habitats from the seed bank is unlikely after established plants have been removed.     

Restoration of the Cirsio dissecti‐Molinietum in The Netherlands: Can we rely on soil seed banks?

Abstract. Vegetation and soil seed banks of a threatened Atlantic fen meadow community were studied using recent phytosociological records and seedling emergence from soil samples. Similarly managed but differently degraded stands that suffered different levels of species impoverishment were compared. The actual vegetation was related to a set of phytosociological references representing the subassociations of the community. DCA positions of reference relevés from the different subassociations were overlapping, suggesting that in all references many common species occur. Recent records were positioned in‐between the seed bank samples and the references. The soil seed banks of all stands were dominated by ordinary species. Most character species had at most sparse seed banks and no seedlings of locally extinct character species, mentioned in historic floristic records, were detected. In contrast species of pioneer and small‐sedge communities as well as those of heathlands were abundant in the seed banks. Based on the vertical distribution of seeds in the soil layers most fen meadow species were classified into transient or short‐term persistent seed bank types. We concluded that complete restoration of the Cirsio dissecti‐Molinietum without reintroduc‐tion is only likely in stands that were degraded only a few years ago. On the other hand, the presence of viable seeds of Nanocyperion and Parvocaricetea species is promising for the restoration of these communities even after decades. Recreation of pioneer habitats by sod cutting will preserve these species.     

Effects of ungulates and prairie dogs on seed banks and vegetation in a North American mixed-grass prairie

The relationship between vegetation cover and soil seed banks was studied in five different ungulate herbivore-prairie dog treatment combinations at three northern mixed-grass prairie sites in Badlands National Park, South Dakota. There were distinct differences in both the seed bank composition and the aboveground vegetation between the off-prairie dog colony treatments and the on-colony treatments. The three on-colony treatments were similar to each other at all three sites with vegetation dominated by the forbs Dyssodia papposa, Hedeoma spp., Sphaeralcea coccinea, Conyza canadensis, and Plantago patagonica and seed banks dominated by the forbs Verbena bracteata and Dyssodia papposa. The two off-colony treatments were also similar to each other at all three sites. Vegetation at these sites was dominated by the grasses Pascopyrum smithii, Bromus tectorum and Bouteloua gracilis and the seed banks were dominated by several grasses including Bromus tectorum, Monroa squarrosa, Panicum capillare, Sporobolus cryptandra and Stipa viridula. A total of 146 seedlings representing 21 species germinated and emerged from off-colony treatments while 3069 seedlings comprising 33 species germinated from on-colony treatments. Fifteen of the forty species found in soil seed banks were not present in the vegetation, and 57 of the 82 species represented in the vegetation were not found in the seed banks. Few dominant species typical of mixed-grass prairie vegetation germinated and emerged from seed banks collected from prairie dog colony treatments suggesting that removal of prairie dogs will not result in the rapid reestablishment of representative mixed-grass prairie unless steps are taken to restore the soil seed bank.     

Species trait shifts in vegetation and soil seed bank during fen degradation

Fens in Central Europe are characterised by waterlogged organic substrate and low productivity. Human-induced changes due to drainage and mowing lead to changes in plant species composition from natural fen communities to fen meadows and later to over-drained, degraded meadows. Moderate drainage leads to increased vegetation productivity, and severe drainage results in frequent soil disturbances and less plant growth. In the present article, we analyse changes in plant trait combinations in the vegetation and the soil seed bank as well as changes in the seed bank types along gradient of drainage intensity. We hypothesize that an increase in productivity enhances traits related to persistence and that frequent disturbance selects for regeneration traits. We use multivariate statistics to analyse data from three disturbance levels: undisturbed fen, slightly drained fen meadow and severely drained degraded meadow. We found that the abundance of plants regenerating from seeds and accumulating persistent seed banks was increasing with degradation level, while plants reproducing vegetatively were gradually eliminated along the same trajectory. Plants with strong resprouting abilities increased during degradation. We also found that shifts in trait combinations were similar in the aboveground vegetation and in soil seed banks. We found that the density of short-term persistent seeds in the soil is highest in fen meadows and the density of long-term persistent seeds is highest in degraded meadows. The increase in abundance of species with strong regeneration traits at the cost of species with persistence-related traits has negative consequences for the restoration prospects of severely degraded sites.