Soil seed banks of woodland, heathland, grassland, mire and montane communities, Cairngorm Mountains, Scotland

The size and species composition of soil seed banks were assessed at 111 altitudinally diverse sites in the Cairngorm Mountains. Mean densities of germinable seeds varied from 83 000 m^–2 in Scots pine (Pinus sylvestris L.) woodland at 230–490 m to 200 m^–2 in moss (Racomitrium lanuginosum (Hedw.) Brid.) heath at 1000–1120 m. Seed banks were dominated by Calluna vulgaris (L.) Hull, not only wherever it was prominent in the vegetation, but also at some sites with less than 5% cover of parent plants in the ground vegetation. Many species conspicuous in the vegetation were under-represented in or absent from the seed bank and surface vegetation generally was more species rich than was the underlying seed bank, especially in high montane communities. Multiple regression was used to examine the relationship between the density of buried Calluna seeds and the abundance of parent plants in the vegetation, site altitude and the organic matter content of the soil. The model fitted to woodland communities accounted for 95% of the variation in seed density. The heathland model was less predictive but still explained 52% of the variation in seed bank size. In mire communities there was no relationship, collective or individual, between buried seed density and the measured environmental variables, possibly due to variations in the duration and frequency of waterlogging at these sites. The potential role of seed banks for initiating the recolonisation of disturbed ground is discussed. Densities of buried seeds at most Calluna-dominant sites were probably sufficient to generate successful recolonisation but the prospects for recovery were poor at other sites, particularly in graminaceous communities at 800 m or higher.     

Unusually high‐quality soil seed banks in a Midwestern U.S. oak savanna region: variation with land use history,habitat restoration,and soil properties

An overarching conclusion in the literature is that soil seed banks rarely contain many restoration‐target species and are often liabilities rather than assets to restoration. Our objective was to evaluate composition and spatial variation of seed banks and their potential contributions to restoration, including restoration‐target species such as rare species and those characterizing historical habitats. On 64 sites in a Midwestern U.S. oak savanna landscape, we sampled soil seed banks in seven habitat types (restored oak savannas, oak woodlands, and mesic prairies; unmanaged upland oak and mesic forests; and unmanaged and managed pine plantations). The germinable seed bank was exceptionally rich in restoration‐target species. In total for the 64 sites, seedlings of 127 species emerged from seed bank samples. Of the 101 native species, 56 were restoration‐target species, an unusually high number among seed bank studies. Restoration‐target species in seed banks included 13 threatened or endangered species, in addition to 43 other specialist species associated with high‐quality native habitats or on a floral list thought to characterize historical ecosystems. When analyzed across the 64‐site gradient, seed banks differed among the seven habitat types and varied with historical (1939) land use, recent management activities that restored open‐structured habitats, and biophysical gradients of tree density, soil drainage, and soil texture. While not all restoration‐target species were detected in the seed bank, the unusually high‐quality seed bank is a potential asset to restoration and was partly structured along environmental gradients across the landscape.     

Role of soil seed bank along a disturbance gradient in an alpine meadow on the Tibet plateau

We examined the role of the soil seed bank along a grazing disturbance gradient and its relationship with the vegetation of alpine meadows on the Tibet plateau, and discussed the implications for restoration. The seed bank had a high potential for restoration of species-rich vegetation; 62 species were identified in the vegetation and 87 in the seed bank, 39 species being common to both. Mean seed density was 3069–6105 viable seeds m⁻². The density of buried seeds increased significantly with increasing disturbance, indicating that restoration of disturbed areas is not seed limited. Seed density and species richness decreased with depth. The proportion of perennial species decreased with decrease in disturbance both in seed bank and in vegetation. A large portion of species with persistent seeds in the disturbed areas indicate that this seed type can be regarded a strategy of adaptation to current disturbances. Detrended correspondence analysis (DCA) showed significant differences of species composition between seed bank and vegetation, except for the seriously disturbed site. Our results suggest that the establishment of new species in severely disturbed areas is more dependent on the seed bank. By contrast, the restoration in less-disturbed and mature meadows does not rely on seed banks, and the establishment of the vegetation in these communities is more likely to rely on seed dispersal from the standing vegetation and on species with vegetative reproduction.     

The relationship between soil seed bank,above‐ground vegetation and disturbance intensity on old‐field successional permanent plots

Questions: How does disturbance and successional age influence richness, size and composition of the soil seed bank? What is the potential contribution of the soil seed bank to the plant community composition on sites differing in their successional age or disturbance intensity? Location: Experimental Botanical Garden of Göttingen University, central Germany. Methods: Above‐ground vegetation and soil seed bank were studied on formerly arable fields in a 36‐year‐old permanent plot study with five disturbance intensities, ranging from yearly ploughing via mowing to long‐term uninterrupted succession. We compared species compositions, seed densities and functional features of the seed bank and above‐ground vegetation by using several methods in parallel. Results: The seed bank was mainly composed of early successional species typical of strongly disturbed habitats. The difference between seed bank composition and above‐ground vegetation decreased with increasing disturbance intensity. The species of greatest quantitative importance in the seed bank was the non‐native forb Solidago canadensis. Conclusions: The ability of a plant community to regenerate from the soil seed bank dramatically decreases with increasing time since abandonment (successional age) and with decreasing disturbance intensity. The present study underlines that plant species typical of grasslands and woodlands are limited by dispersal capacity, owing to low capacity for accumulation of seeds in the soil and the fact that most species do not build up persistent seed banks. Rare and target species were almost absent from the seed bank and will, after local elimination, depend on reintroduction for continuation of their presence.     

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.     

Seasonal wetlands on the Lake Wales Ridge, Florida: does a relict seed bank persist despite long term disturbance?

Wetlands maintain biodiversity and provide numerous ecosystem services, so the pressure to perform successful restoration consequently is high. However, restoration projects rarely include an in-depth assessment of wetland potential for recovery, and restoration techniques may not be tailored to site-specific concerns. This study examined the seed bank of disturbed wetlands slotted for hydrologic, but not vegetation, restoration to determine if a seed bank comparable to that of nearby undisturbed wetlands persisted despite long-term anthropogenic disturbance. We compared the aboveground vegetation and seed bank compositions under drained, drawdown, and flooded conditions between undisturbed and historically ditched (“disturbed”) wetlands. Disturbed and undisturbed wetlands shared fewer than 30 % of total aboveground species. While undisturbed wetlands were dominated by graminoids, disturbed wetlands had greater cover of forbs. The seed banks of disturbed wetlands had high species diversity, but their composition was dissimilar to that of nearby undisturbed wetlands. In total, the seed banks of both disturbance histories germinated 56 species; drained conditions had the fewest germinants while flooded conditions had the most. Germinant richness was significantly affected by disturbance, moisture, and their interaction; evenness was significantly affected by moisture, and Shannon diversity by disturbance. Because the seed bank of disturbed wetlands included many fast-growing wetland plants, passive vegetation restoration and active hydrologic restoration may result in wetlands overgrown with weedy species and with fewer conservative wetland plants. An understanding of the capacity for seed banks to re-vegetate wetlands post-restoration and approximate undisturbed wetlands is crucial to the overall success of restoration projects.     

Recruitment limitation of native species in invaded coastal dune communities

Recruitment limitation may limit the ability of sites to regenerate after disturbances such as weed invasion and weed management. We investigated seed bank constraints and dispersal limitation in coastal dune communities on the east coast of Australia. The ability of sites to regenerate naturally following weed removal was assessed in coastal dune communities invaded by the invasive alien, bitou bush (Chrysanthemoides monilifera subsp. rotundata). To investigate recruitment limitation, seed banks and vegetation of invaded, native, intensively managed (selective application of herbicide and some re-vegetation) and extensively managed (large-scale, non-selective herbicide application) sites were compared. We investigated the dispersal mechanisms of species in the seed bank and vegetation to determine if communities might be dispersal-limited, i.e. contain significant numbers of species with only short-distance dispersal capabilities. Species richness and composition of soil seed banks differed from the vegetation in foredunes and hinddunes. Invasion depleted seed banks further. About half of the species had short-distance dispersal mechanisms indicating the potential for dispersal limitation. Secondary weed invasion following management was evident although alien species occurred in both seed banks and vegetation. Our results indicated that coastal dune communities suffer recruitment limitation. Native, managed and invaded dune communities appear to be both seed bank and dispersal-limited although management and invasion exacerbates recruitment. Regeneration of coastal dune communities will require active reintroduction of species, particularly those with short-distance dispersal mechanisms.     

Depth distribution and composition of seed‐banks in alien‐invaded and uninvaded fynbos vegetation

South African fynbos vegetation is threatened on a large scale by invasive woody plants. A major task facing nature conservation managers is to restore invaded areas. The aim of this study was to determine the restoration potential of fynbos following dense invasion by the Australian tree Acacia saligna. The impacts of dense invasion on seed‐bank composition and depth distribution were investigated to determine which fynbos guilds and species have the most persistent seed‐banks. Soil samples were excavated at three different depths for invaded and uninvaded vegetation at two sand plain and mountain fynbos sites. Seed‐banks were determined using the seedling emergence approach. Invasion caused a significant reduction in seed‐bank density and richness at all sites. There was a significant, but smaller, reduction in seed‐bank density and richness with soil depth at three sites. Seed‐bank composition and guild structure changed following invasion. Low persistence of long‐lived obligate seeders in sand plain fynbos seed‐banks indicates that this vegetation type will be difficult to restore from the seed‐bank alone following alien clearance. The dominance of short‐lived species, especially graminoids, forbs and ephemeral geophytes, suggests that regenerating vegetation will develop into a herbland rather than a shrubland. It is recommended that seed collecting and sowing form part of the restoration plan for densely invaded sand plain sites. As seed density remained higher towards the soil surface following invasion, there is no general advantage in applying a mechanical soil disturbance treatment. However, if the shallow soil seed‐bank becomes depleted, for example following a hot fire through dense alien slash, a soil disturbance treatment should be given to exhume the deeper viable seed‐bank and promote recruitment.     

The seed bank in an estonian calcareous grassland: Comparison of different successional stages

Seed bank species-composition and seed-density were determined in a successional calcareous (alvar) grassland in western Estonia. Three similar study areas were chosen to compare two different successional stages: open alvar grassland and overgrown areas with young pine forest 30 to 40 years old. In both successional stages, the centre and the edge of a relatively uniform stand were examined. Fifteen soil samples (7 cm in diameter, 5 cm deep) were taken from each of twelve sampling sites. The seedling emergence method was used to estimate seeds in the soil samples. A total of 69 species were detected in the seed bank, of which 18 did not occur in the vegetation. Eighty-nine taxa were recorded in the vegetation and of these 38 were not detected in the seed bank. Fifty-one species occurred both in the seed bank and in the vegetation. The three most abundant taxa in the seed bank wereCarex tomentosa, Linum catharticum andPlantago media, which together made up 49% of the seedlings recorded. Differences in the species compositions of seed bank samples from grassland and forest sites were negligible, although the species richness per area of the above-ground vegetation was significantly higher in the open grassland. The only species tending to be lost from forest site vegetation but still occurring in the forest soil seed bank wereArenaria serpylifolia, Cerastium fontanum andLinum catharticum. About half of all the emerged species from all samples belonged to the transient or short-term persistent seed bank. In the grassland sites there were more species which belonged to the transient seed bank than in the forest sites, where the seed bank contained more short-term persistent type seeds. The seed density was significantly higher in forest sites and lower in grassland sites, which may be explained by the better germination conditions in well-illuminated communities. On the basis of the current study it might be assumed that the soil seed banks of overgrown alvar grasslands which include young pine forests can play a certain role in grassland restoration management.     

Can Managers Bank on Seed Banks When Restoring Pinus taeda L. Plantations in Southwest Georgia?

In the southeastern United States, private forestland managers are under increased pressure to provide wildlife habitat and biodiversity in addition to commercial products such as timber. This study used a stand classification scheme based on vegetation biodiversity from Hedman et al. to compare seed bank composition of benchmark (BM) and nonbenchmark (NBM) Loblolly pine ( Pinus taeda ) stands. In the Hedman et al. study, BM stands contained species associated with Longleaf pine ( P. palustris )/Wiregrass ( Aristida stricta ) communities, whereas NBM stands contained species associated with disturbed sites. The current vegetation of the BM and NBM stands had an average cover of 7.9%/m² and an average richness of 11 species/m². The intent for this study was to assist in understanding the potential role of the seed bank during stand development and restoration. We collected seed bank samples from six pine plantations in the winter of 2006. Seed bank samples yielded 2,885 germinants representing 56 unique species but only 4 were found in both current herbaceous vegetation plots and seed bank. The seed bank was dominated by native dicots. In BM stands, 76% of species were native, whereas in NBM stands, 69% were native. Seed bank samples from NBM stands had greater species richness ( p = 0.03) and total germinants ( p = 0.03) than BM stands. Although the seed bank in all stands was dominated by native species, our data suggest that the seed bank under P. taeda stands should not be viewed as the sole source of native species for most restoration goals.     

Restoration of ditch bank plant species richness: The potential of the soil seed bank

Abstract. Small‐scale landscape elements, such as ditch banks, play an important role in preserving plant species richness in agricultural landscapes. In this study, we investigate whether the seed bank might be useful for restoring the above‐ground plant species richness. We studied the vegetation and seed bank composition at six species‐rich and six species‐poor ditch banks, where agri‐environment schemes are running to maintain and enhance ditch bank plant diversity. We show that the number of species in the seed bank was low, regardless of the number of species in the established vegetation. Moreover, the seed bank was always dissimilar to the established vegetation. Target species for nature conservation were occasionally present in the seed bank at both species‐poor and species‐rich sites, but rarely so if the species was absent from the established vegetation. We conclude that the potential use of the seed bank for restoration of ditch banks is minimal. At present, plant species richness seems to be largely controlled by germination opportunities; high biomass and competition appear to hamper germination at species‐poor sites. We recommend continued nutrient reduction at such sites. Soil disturbance measures and deliberate sowing should also be considered.     

A comparison between reclamation stockpile and boreal forest seed banks and plant communities

Soil stockpiles are essential to the reclamation of large‐ and small‐scale mining and other industrial sites. However, stockpiling soils can lead to the degradation of seed banks. This study examines the diversity, composition, depth of seed storage, and relationships between the aboveground and seed bank plant communities in stockpiles and compares them to the nearby boreal forest. The seed bank and aboveground vegetation sampled at eight stockpiles and six mature forest sites were near Fort McMurray (57.337°N, 111.755°W) and Cold Lake (54.695°N, 110.730°W), Alberta, Canada. Seed bank samples were taken from the forest floor (LFH) and depths of 0–5, 5–10, 10–20, 20–30, >50 cm. Aboveground vegetation cover was also estimated at these locations. The seed bank composition was determined using the seedling emergence method in a greenhouse. Stockpile seed banks had higher seedling abundance and species richness than nearby forested sites but were dominated by grasses and non‐native forbs. Most seeds germinated from the surface layer, with 92% of seeds germinating from the LFH layers in the forested sites, and 68% from the 0 to 5 cm layer in the stockpiles. Mature forest sites had more similar aboveground and seed bank communities than the stockpiles. Overall, integrating information on seed bank and aboveground plant communities would improve reclamation decisions, rather than relying on aboveground vegetation alone.     

Seed banks are biodiversity reservoirs: species–area relationships above versus below ground

Soil seed banks offer plants the possibility to disperse through time. This has implications for population and community dynamics, as recognised by ecological and evolutionary theory. In contrast, the conservation and restoration literature often find seed banks to be depauperate, weedy and without much conservation value or restoration potential. One explanation for these contrasting views might lie in a systematic bias in the sampling of seed banks versus established plant communities. We use the species–area relationship as a tool to assess and compare the per‐area species richness and spatial structuring of the diversity of the established plant community versus soil seed banks. To allow this direct comparison we extensively survey the species–area relationship of the vegetation and underlying seed bank of a grassland community across twelve sites spanning regional bioclimatic gradients. We also compile a global dataset of established vegetation and seed banks from published sources. We find that seed banks have consistently higher intercepts and slopes of the relationship, and hence higher diversity at any given spatial scale, than the vegetation both in the field and literature study. This is consistent across habitat types, climate gradients, and biomes. Similarity indices are commonly used to compare vegetation and seed bank, and we find that sampling effort (% of the vegetation area sampled for seed bank) was the strongest predictor of vegetation–seed bank similarity for both the Sørensen (R² = 0.70) and the Raup–Crick (R² = 0.25) index. Our study suggests that the perception that seed banks are intrinsically less diverse than established plant communities has been based more on inadequate sampling than on biological reality. Across a range of ecosystems and climatic settings, we find high diversity in seed banks relative to the established community, suggesting potentially important roles of seed banks in population dynamics and diversity maintenance.     

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.     

Land‐use history,historical connectivity,and land management interact to determine longleaf pine woodland understory richness and composition

Restoration and management activities targeted at recovering biodiversity can lead to unexpected results. In part, this is due to a lack of understanding of how site‐level characteristics, landscape factors, and land‐use history interact with restoration and management practices to determine patterns of diversity. For plants, such factors may be particularly important since plant populations often exhibit lagged responses to habitat loss and degradation. Here, we assess the importance of site‐level, landscape, and historical effects for understory plant species richness and composition across a set of 40 longleaf pine Pinus palustris woodlands undergoing restoration for the federally endangered red‐cockaded woodpecker in the southeastern United States. Land‐use history had an overarching effect on richness and composition. Relative to historically forested sites, sites with agricultural histories (i.e. former pastures or cultivated fields) supported lower species richness and an altered species composition due to fewer upland longleaf pine woodland community members. Landscape effects did not influence the total number of species in either historically forested or post‐agricultural sites; however, understory species composition was affected by historical connectivity, but only for post‐agricultural sites. The influences of management and restoration activities were only apparent once land‐use history was accounted for. Prescribed burning and mechanical overstory thinning were key drivers of understory composition and promoted understory richness in post‐agricultural sites. In historically forested sites these activities had no impact on richness and only prescribed fire influenced composition. Our findings reveal complex interplays between site‐level, landscape, and historical effects, suggest fundamentally different controls over plant communities in longleaf pine woodlands with varying land‐use history, and underscore the importance of considering land‐use history and landscape effects during restoration.     

May seed banks contribute to vegetation restoration on paths in temperate deciduous forest?

Forest paths are characterised by a zonation in vegetation composition as a result of gradients in abiotical conditions and continued recreational impact. Little is known about how much seed bank composition is affected by recreation and the existing path structure. As it is difficult to assess the contribution of seed banks to vegetation restoration, this study imparts relevant knowledge to restore vegetation on paths which are closed for recreational use. We surveyed seed bank and field layer vegetation composition in transects across path ecotones in deciduous forest. Analysis concentrated on seed bank characteristics and similarities of the seed bank and field layer vegetation in terms of ecological and seed size groups. A total of 74 species and 9,815 seedlings germinated out of the seed bank samples. The total seed density does not differ between path zones, but significant differences exist in the depth distribution and composition of the seed bank throughout transects. There is a large discrepancy between the composition of the seed bank and the vegetation. Small seeded species of disturbed environments dominate in each path zone. Typical forest species dominate in the vegetation while their contribution to the seed bank is low. Only with reference to the proportion of species of forest edges and clearings, the seed bank and vegetation do not differ significantly. Similarity between the seed bank on the path centre and the vegetation in the respective path zones decreases towards the undisturbed forest vegetation. Some competitive species like Urtica dioica and Lythrum salicaria are excessively represented in the seed bank and efficiently may obstruct further visitor use. However, these early successional species may not contribute to the conservation values of forests. Therefore management should carefully consider alternative amendments (e.g. soil scarification and seeding) to stimulate vegetation restoration.     

The seed banks of English lowland calcareous grasslands along a restoration chronosequence

We investigated whether the seed banks of ex-arable lowland calcareous grasslands underwent restoration similar to that of the above-ground restoration, and whether this was influenced by seed-sowing or environmental conditions. We compared 40 sites, where some form of restoration work had been implemented between 2 and 60 years previously, with 40 paired reference sites of good quality calcareous grassland with no history of ploughing or agricultural improvement. We analysed differences between sites and between above- and below-ground vegetation using both a multivariate approach and proportions of selected plant attributes. Seed banks of reference sites were more characteristic of late successional communities, with attributes such as stress tolerance, perenniality and a reliance on fruit as the germinule form more abundant than in restoration sites. In restoration sites, these tended to decrease with restoration site isolation and increase with restoration site age and where soil nutrient conditions were more similar to reference sites (i.e. with relatively low phosphorus and high nitrogen). Seed bank communities of all sites differed considerably from above-ground communities, however, and no overall significant responses to site age, isolation or soil nutrients were detected by multivariate analyses of similarity of species between pairs of sites. Responses to different seeding methods were also barely detectable. While there is some indication from the plant attribute data that the regeneration potential contained in the seed banks of restored sites increasingly resembles that of references sites over time, even seed banks of good quality calcareous grassland are dominated by ruderal species. It is likely, therefore, that permanent seed banks do not facilitate the restoration of ex-arable grasslands.     

Effects of the litter layer of Pteridium aquilinum on seed banks under experimental restoration

Questions: Does the litter layer of Pteridium aquilinum (bracken) act as a barrier to certain species in the seed bank? Does bracken control/restoration treatment affect seed transfer through the litter layer? Location: Five experiments at three sites across the UK covering two major vegetation types; acid‐grassland and heath‐land. Methods: At each experiment a range of bracken control and vegetation restoration treatments were applied for about ten years. The seed bank was sampled in both the bracken litter and the soil. The cover (%) of each species in the vegetation and the bracken litter abundance (cover and depth) was also estimated. Results: The bracken litter layer acts as an inert barrier as it contained a large proportion of seeds available in the litter‐soil profile (38%– 67% of the total). Bracken litter depth and cover also influenced significantly the seed bank composition in both the bracken litter and the soil. These effects were site‐specific, and species‐specific. The application of treatments changed significantly the balance between seed inputs and outputs in the bracken litter layer for some species. This was either a positive or negative response relative to the untreated control plots. Conclusion: For heathland and acid‐grassland restoration, the bracken litter layer may be an important seed source, but it must be disturbed particularly before seed addition.     

Soil seed bank in different vegetation types in the Loess Plateau region and its role in vegetation restoration

In the Loess Plateau region, soil erosion is a serious problem. Vegetation restoration is an effective approach to control soil erosion and improve ecosystems. The soil seed bank generally plays an important role in vegetation restoration after disturbance. Thus, we reviewed soil seed bank studies to reveal the soil seed bank characteristics and its role in vegetation restoration in three vegetation types (forest, forest‐steppe, and steppe). We selected 38 seed bank studies and analyzed several seed bank characteristics, such as seed density, species composition, and the relationship between seed size and seed bank. We also assessed the role of the soil seed bank in vegetation restoration. The soil seed bank density ranged from 2,331 ± 1,993 to 6,985 ± 4,047 seeds/m² among the different vegetation types. In the soil seed bank, perennial herbs and grasses accounted for 51.5% of the total species. Native species that were dominant or common in the standing vegetation usually had relatively high seed bank densities. Moreover, species with smaller seeds generally had higher soil seed bank densities. The present study indicates that the soil seed bank plays a significant role in spontaneous vegetation restoration, especially during the early successional stages in abandoned slope farmlands and grazing‐excluded grasslands. However, species with large seeds or transient soil seed banks should be reintroduced through seeding to accelerate target species restoration. More studies on soil seed banks need to be conducted to comprehensively reveal their characteristics.     

The potential of soil seed banks of a eucalypt wetland forest to aid restoration

Soil seed banks can play an important role in the regeneration of wetland vegetation. However, their potential role in the restoration of degraded wetland forests is less certain. I surveyed the soil seed bank and extant floras of four sites across a eucalypt wetland forest of variable vegetation condition. At each site, the extant vegetation was surveyed within two 5 × 5 m² quadrats, each from which five composite soil seed bank samples were collected. Across the four sites, 57 (including 18 exotic) species were identified in the extant vegetation, while from the seed bank samples 6379 seedlings emerged from 80 taxa, 33 of which were exotic species. The soil seed bank was dominated by native and exotic monocots, and contained very few seeds of wetland tree or shrub species. Overall, the similarity between the extant and seed bank floras was very low (~24 %). Soil seed banks are likely to be of limited use in the restoration of degraded wetland forests, because the dominant species in such systems—woody and clonal plants—are typically absent from the soil seed bank. Wetland soil seed banks may contribute to the maintenance and diversity of understorey vegetation, however, they may also act as a source of exotic plant invasions, particularly when a wetland is degraded.