Comparison of two methods characterising the seed bank of amphibious plants in submerged sediments

We analysed the submerged soil seed bank of three fishponds in the Waldviertel region in Austria. We aimed our study at comparing the efficiency of two methods in detecting seeds quantitatively from soil samples of four characteristic mud-flat species, i.e. Carex bohemica, Coleanthus subtilis, Elatine hexandra, and Eleocharis ovata: the seedling-emergence and the rinsing method. Additionally, the actual vegetation was described based on 65 phytosociological relevés. Soil seed bank analyses were based on 31 samples representing the vegetation zonation. Mixed soil samples were portioned into 62 subsamples further treated with the two methods in parallel.     

Effects of 10-Year Management Regimes on the Soil Seed Bank in Saline-Alkaline Grassland

Background

Management regimes for vegetation restoration of degraded grasslands can significantly affect the process of ecological succession. However, few studies have focused on variation in the soil seed bank during vegetation restoration under different management regimes, especially in saline-alkaline grassland habitats. Our aim was to provide insights into the ecological effects of grassland management regimes on soil seed bank composition and vegetation establishment in mown, fenced, transplanted and natural grassland sites, all dominated by the perennial rhizomatous grass Leymus chinensis.

Methodology

We studied species composition and diversity in both the soil seed bank and aboveground vegetation in differently managed grasslands in Northeast China. An NMDS (nonmetric multidimensional scaling) was used to evaluate the relationship between species composition, soil seed banks, aboveground vegetation and soil properties.

Principal Findings

Fenced and mown grassland sites had high density and species richness in both the soil seed bank and aboveground vegetation. The Transplanted treatment exhibited the highest vegetation growth and seed production of the target species L. chinensis. Seeds of L. chinensis in the soil occurred only in transplanted and natural grassland. Based on the NMDS analysis, the number of species in both the soil seed bank and aboveground vegetation were significantly related to soil Na⁺, Cl^-, RSC (residual sodium carbonate), alkalinity, ESP (exchangeable sodium percentage) and AP (available phosphorus).

Conclusions

Soil seed bank composition and diversity in the saline-alkaline grassland were significantly affected by the management regimes implemented, and were also significantly related to the aboveground vegetation and several soil properties. Based on vegetative growth, reproductive output and maintenance of soil seed bank, the transplanting was identified as the most effective method for relatively rapid restoration of the target species L. chinensis. This approach could be beneficial for the restoration of dominant species in a wide range of degraded grassland ecosystems.     

Persistent soil seed banks and floristic diversity in Fagus orientalis forest communities in the Hyrcanian vegetation region of Iran

We assessed the size of seed bank, species diversity and similarity between seed bank and standing vegetation in four oriental beech (Fagus orientalis Lipsky) community types of the central Hyrcanian forests of northern Iran. For this purpose a total of 52 relevés was established in two associations and two subassociations of the beech forests, and six soil samples (20 × 20 cm square and to a depth of 10 cm) were collected in each relevé in mid-spring, after the germination season had ended. Soil seed bank was investigated using the seedling emergence method. A total of 63 species, 57 genera and 36 families was represented in the persistent soil seed bank of the forest communities. The seed bank contained 28 species not found as adult plants in the vegetation, but these were mostly early successional species. Size of the seed bank ranged from 3740 to 4676 individuals m⁻² in the Rusco hyrcani-Fagetum orientalis and Danae racemosae-Fagetum orientalis associations, respectively. Species composition of seed banks and aboveground vegetation had low similarity with an average of 24.3% in the four plant communities, because only 38% of the species were the same in the vegetation and the seed banks. Most seeds in the seed bank were from early successional species, and the only tree with a large persistent seed bank was the fast-growing pioneer Alnus subcordata. DCA ordination also demonstrated low similarity between soil seed bank and vegetation. The soil seed banks of the four beech communities did not differ significantly in size, composition, diversity and uniformity. Although above ground vegetation in the four community types is floristically distinct, there is considerable overlap among the soil seed banks because they contain in a similar way early successional species. Further, the absence of typical forest species in the soil seed bank indicates that restoration of forest tree species cannot rely on the soil seed bank.     

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.     

Successful restoration of abandoned terraced vineyards and grasslands in Southern Switzerland

Extensively managed semi-natural grasslands represent species-rich habitats and therefore play a key role for the maintenance of biodiversity in agricultural areas. In marginal and poorly accessible areas, the traditional management of grassland is frequently abandoned, which leads to the spread of forest. In Southern Switzerland, terraced vineyards (a special grassland type) and terraced grasslands are part of the cultural heritage and local biodiversity hotspots. Yet, many of them are overgrown by forest. In the past years, several abandoned terraced vineyards and grasslands have been restored by removing the forest, rebuilding the walls and re-introducing the traditional management. We examined restoration success by assessing plant species richness, diversity and species composition in both the aboveground vegetation and soil seed bank in (1) restored, (2) abandoned for 25–50 years, and (3) permanently used areas of six terraced vineyards and six terraced grasslands. Plant species richness and diversity were reduced and species composition altered in the aboveground vegetation of abandoned vineyards and grasslands compared to the permanently used and restored ones. However, species richness, Shannon-diversity and species composition of the aboveground vegetation did not differ between restored and permanently used areas, indicating a successful restoration of the vegetation 10–15 years after restoration. In abandoned vineyards, species richness of plants emerging from the soil seed bank was slightly higher than in permanently used and restored vineyards. No difference in seedling species richness was found between abandoned, permanently used and restored terraced grasslands. Our results showed that the soil seed bank played a minor role for the re-establishment of the above-ground vegetation. We assume that the large species pool in the surroundings and the presence of dispersal vectors are essential for the successful passive restoration of abandoned grassland in this region.     

Seed bank offers potential for active restoration of mountain meadows

The nitrogen‐fixing legume Lupinus polyphyllus invaded semi‐natural mountainous grasslands across Europe during the last decades. This invasion resulted in degraded habitats through changes in the structure and function of the mountain meadow vegetation. In our study, we analyzed (1) the effects of increasing cover of L. polyphyllus on the seed bank of mountain meadows, and (2) the potential of the seed bank of these stands for active restoration of mountain meadows in terms of species composition and number. We conducted a seed bank analysis on 84 plots with increasing cover of L. polyphyllus in three mountain‐meadow types of the Rhön Biosphere Reserve, Germany. Seedlings from 119 species germinated from the seed bank samples, including 17 Red List species but only a few seedlings of L. polyphyllus. The species composition of the seed bank matched distinct patterns of the three meadow types, but differed from the species composition of the current aboveground vegetation in a nonmetric multidimensional scaling ordination. While the influence of L. polyphyllus on the current vegetation was visible, no effects on the seed bank were apparent. L. polyphyllus had no influence on total seed density, seed density of typical mountain‐meadow species, or species numbers in the seed bank. Only the seeds of the Red List species were significantly related to the cover of L. polyphyllus. We conclude that the seed bank offers potential for active restoration of species‐rich mountain meadows, but species absent from the seed bank have to be added by other measures.     

Seasonal variation in seed bank composition and its interaction with nutrient enrichment in the Everglades wetlands

In the Florida Everglades, nutrient enrichment from agricultural outflow and the change in hydrology have collectively contributed to the expansion of cattails (Typha spp.). To assess the effectiveness of prescribed fire in controlling cattails and to predict vegetation dynamics after the fire, it is important to understand the seasonal variation of the soil seed bank and how the seed bank is affected by nutrient enrichment and fire. This paper investigates the effects of season, nutrient enrichment, and fire on soil seed bank species composition, richness, and density along a nutrient gradient in Water Conservation Area 2A (WCA 2A) of the Florida Everglades. Species richness was significantly affected by nutrient enrichment and season but not their interaction. Total seed density, however, was significantly affected by the interaction between nutrient enrichment and season. Yet, at species level, the relationship between seed density, nutrient enrichment and season varied. The highest seed density of cattail occurred in summer at highly enriched sites, but that of sawgrass occurred in fall regardless of enrichment; the seed density of water lily was very low regardless of season and nutrient enrichment, and the highest Amarathus seed density occurred at highly enriched sites year round. Moreover, germination timing differed greatly among species. While cattail seeds had a short incubation period and started to germinate 2–3 days after initiation of the germination assay, sawgrass seeds generally started to germinate 4 weeks later. Further, both the prescribed summer fire at the highly enriched site and the natural winter fire at the moderately enriched site reduced the seed density of cattail but not of sawgrass. Our results suggest that fire application for vegetation recovery in WCA 2A would benefit from explicitly considering seasonal dynamics of the seed bank.     

Repeated mowing to restore remnant native grasslands invaded by nonnative annual grasses: upsides and downsides above and below ground

California grasslands have been severely impacted by the invasion of nonnative annual grasses, which often limit restoration of this important ecosystem. In this study, we explored the use of mowing as a restoration tool for native perennial grasslands at the Santa Rosa Plateau Ecological Reserve in southern California. We sought to evaluate if, over time, mowing would reduce nonnative annual grass cover and benefit native species, especially the native bunchgrass Stipa pulchra. We hypothesized that repeated mowing, carefully timed to target nonnative annual grasses prior to seed maturation, would reduce nonnative seed inputs into the soil and eventually lead to diminished abundance of these species. We monitored vegetation in mowed and unmowed plots for 4 years, and conducted a seed bank study after 5 years to better understand the cumulative effects of mowing on native and nonnative seed inputs. Consistent with our hypotheses, we found that mowing successfully reduced nonnative annual grass cover and benefitted some native species, including S. pulchra. However, we also found that nonnative forb species showed progressive increases in mowed plots over time. We observed similar patterns of species composition in the soil seed bank. Together, these results suggest that mowing can be used to control nonnative annual grasses and increase the abundance of native bunchgrasses, but that this method may also have the unintended consequence of increasing nonnative forb species.     

Resilience,persistence and relationship to standing vegetation in soil seed banks of semi‐arid Australian old fields

Questions: Do soil seed banks of semi‐arid grasslands reassemble after abandonment from cultivation? Do seeds of native and exotic species persist in the soil? Does time since abandonment affect compositional similarity between the vegetation and seed bank? Does the seed bank contribute to resilience in the vegetation? Location: Native grasslands in northern Victoria, Australia. Methods: Seed bank sampling was conducted in spring and autumn over 3 yrs, across a 100‐yr chronosequence. Species richness, composition and germinant density were determined using the seedling emergence method. Seed persistence was assessed by comparing seed densities in spring and autumn. Seed bank composition was compared with the vegetation. Results: The spring seed bank was dominated at all stages by sedges and rushes; hence, native species richness and seed density were largely unaffected by abandonment. In autumn, grassland species contributed more to the seed bank, but richness was reduced after abandonment and showed little recovery, although seed density partially recovered. Seed bank composition showed some recovery in both seasons. Most species had low persistence in the soil. Compositional similarity between the vegetation and seed bank was greater in old fields than uncultivated grasslands in spring, but not autumn. Conclusions: Resilience varied among seed bank parameters and seed banks had low functional importance. Patterns in the seed bank followed, rather than caused, those in the vegetation. Thus, vegetation recovery cannot rely on the seed bank and persistent seeds were not the key mechanism of resilience in the vegetation.     

Small seed bank in grasslands and tree plantations in former grassland sites in the South Brazilian highlands

The soil seed bank can be an important source for vegetation regeneration, and data on the similarity between aboveground vegetation and the seed bank can provide information about successional pathways after disturbances or land-use change. We conducted this study in natural grasslands in the subtropical highland region in southern Brazil. We evaluated the effect of silviculture on richness, density, and composition of the seed bank at former grassland sites converted to pine plantations 25 years ago. We worked at six grassland sites and three pine plantation sites and used the seedling emergence method. Seed bank density and richness in grasslands were lower than those reported in similar environments in other regions. Species richness and density varied considerably within each vegetation type; therefore, richness and density were not statistically significant, while composition varied among vegetation types. In terms of species, the pine plantation seed bank was a small subset of the grassland seed bank. Seeds of typical grassland species were missing in the pine plantation, but also had only low abundances in the grassland, and similarity of seed bank and vegetation were low (less than 20%). The low seed density found in this study, including in grasslands areas, indicates that regeneration of species from the soil seed bank likely is of a limited role for the maintenance of plant populations after disturbances in this system. Our data further suggest that natural regeneration after tree planting in grasslands is reduced due to seed limitation.     

Composition and seasonal flux of the soil seed bank of species-rich Themeda triandra grasslands in relation to burning history

Abstract. Most species-rich grasslands dominated by Themeda triandra in southeastern Australia have been ungrazed and frequently burnt for decades. The seedling emergence technique was used to determine the size and taxonomic composition of the soil seed bank of five grasslands that had different fire histories (i.e. burnt at 1 yr, 3 yr and > 10 yr intervals) and this was compared to the standing vegetation at each site. A nested sampling design (subplot, plot, site) was used to determine the effect of spatial scale on the patterns observed in both the vegetation and the seed bank. Temporal variation in the seed bank was assessed by repeated soil sampling over a two year period. 61 native and 30 exotic species were recorded in the vegetation. Richness varied more between sites than within sites. Sites were therefore internally homogeneous for species richness. However, no correlation between burning frequency and richness was found. DCA ordination separated the sites into distinct groups, but sites with similar fire history did not necessarily group closely. 60 taxa germinated from the soil seed bank, comprising 32 native and 28 exotic species; 11 species, mostly therophytes, were restricted to the seed bank. The richness of the seed bank was significantly lower than the vegetation at all spatial scales. No correlation between seed bank richness and fire history was found. The seed bank of species-rich grasslands is dominated by a limited number of widespread, highly clumped, annual, native and exotic monocots. Most native hemicryptophytes, and perennials in general, were represented in the soil by a transient seed bank. Only 12 % of study species, all therophytes, were considered to form large, persistent seed banks, the size of which was greater in unburnt grasslands at all times of the year. The distinct floristic patterns observed in the vegetation are less clearly represented in the seed bank. The seed bank represents a floristically distinct (and less variable) component of the vegetation when compared to the standing flora. The size of the long-term soil seed bank suggests that it has little functional importance for many native species and probably contributes little to seedling regeneration processes following disturbance. Altering established fire regimes is likely to only change the composition and small-scale richness of the existing site vegetation and will not re-integrate species previously lost from the vegetation due to past management. It is suggested that the maintenance of vegetation remnants and processes that encompass a range of long-term burning histories will be necessary if the flora is to be conserved in situ. Restoration of degraded grasslands cannot rely on the soil seed bank but rather, will be dependent on the reintroduction of propagules.     

天山中部天山云杉林土壤种子库年际变化

通过定点采样,采用萌发法对天山中部天山云杉(Picea schrenkiana Fisch.et Mey.)近熟林(101-120a)和成熟林(121-160a) 2004-2011年(8a)土壤种子库物种组成、种子密度的年际变化和不同间隔年限土壤种子库物种组成的相似性进行了分析.结果表明:(1)土壤种子库中共萌发鉴定出种子植物87种,隶属29科70属,其中乔木种子植物2种,灌木种子植物2种,草本种子植物83种,土壤种子库中草本植物种子密度远远大于木本植物种子密度;8个采样年份土壤种子库恒有种仅有6种;(2)土壤种子库种子密度及其中天山云杉种子密度存在巨大的年际变动,且不具有同步性;土壤种子库种子密度最大(2009年)值为(953.75±66.12)粒/m2,最小(2008年)值为(186.50±20.37)粒/m2,其中天山云杉种子密度最高(2006年)达到(584.50±53.58)粒/m2,最低(2005年)仅有(0.25±0.26)粒/m2;(3)天山云杉林土壤种子库年际间物种组成的相似性不高,Czekanowski相似系数均值仅为0.344,并随间隔年限的增加呈现减小—增大—减小的变化趋势.天山云杉林土壤种子库物种组成和种子密度稳定性差,年际间相差悬殊,物种组成的相似性不高,种子库中天山云杉种子密度主要受其种子库采样前一年天山云杉结实丰歉的影响,属间断型.土壤种子库年际变化特征可为天山森林的更新恢复和可持续经营提供科学依据.     

Germinable soil seed banks in abandoned grasslands in central and western Norway and their significance for restoration

Questions: Could the seed bank increase biodiversity during restoration of abandoned, species‐poor, formerly cultivated vegetation? Is it possible to identify how climate, soil and former and present management and vegetation affected the seed bank? Location: The study sites were eight abandoned grasslands, four in Orkdal, central Norway and four in Gaular, western Norway. Methods: 144 seed bank samples were collected from three depths. Each sample was sown and placed in a greenhouse. After three months, the trays were dried and stored at 4°C in a dry place for two months. This was repeated twice. Results: There was a separation of the two regions along the first DCA axis in both the seed bank and in the vegetation analysis and also a clear separation of the seed bank from the vegetation along the second axis. These results are caused by differences in former management as well as temperature, precipitation and soil type between Gaular and Orkdal. We found more annuals, short‐lived species and species demanding light open conditions in the seed bank than in the vegetation probably because these species have the capacity for producing persistent seeds. Most of the species found only in the seed bank were found in very few samples and with few individuals. Conclusion: These results suggest that it may be difficult to increase vegetation biodiversity through restoration of grasslands such as those investigated if the natural soil seed bank is the main seed source.     

Comparison of aboveground vegetation and soil seed bank composition at sites of different grazing intensity around a savanna-woodland watering point in West Africa

Grazing removes a plant’s aboveground vegetative and reproductive tissues and can modify the soil seed bank, potentially impacting the restoration of preferred species. Knowledge about aboveground vegetation and species composition of soil seed bank and the processes that contribute to vegetation recovery on and surrounding watering points subjected to grazing is lacking. Successful restoration strategies hinge on addressing these knowledge gaps. We assessed the effects of livestock grazing on aboveground vegetation and soil seed bank characteristics along a river bank and surrounding areas subject to different grazing intensities and draw implications for restoration. Plots (50?×?50 m) were established along five transects representing differing levels of grazing intensity. Soil samples were taken from three layers within each plot to determine soil properties and species composition of soil seed bank using the seedling emergence method. Heavy grazing resulted in the disappearance of perennial grasses, a reduction in species diversity and a decrease in soil nutrients with increased soil depth. Overall, the similarity between the extant aboveground vegetation and flora within the soil seed bank was low. The soil seed bank was dominated by herbaceous species and two woody species, suggesting that many woody species are not accumulating in the soil. With increasing soil depth, the seed density and richness declined. Canonical correspondence analyses (CCAs) showed that emerged seedlings from the soil seed bank were significantly influenced by soil carbon, organic matter, total nitrogen, total potassium and soil cation exchange capacity. This finding suggests that current grazing practices have a negative impact on the vegetation surrounding watering points; hence there is a need for improved grazing management strategies and vegetation restoration in these areas. The soil seed bank alone cannot restore degraded river banks; active transfer of propagules from adjacent undisturbed forest areas is essential.     

Soil seed-bank composition reveals the land-use history of calcareous grasslands

We compared soil seed banks and vegetation of recent (established on abandoned arable fields) and ancient (continuously managed as pastures at least since 1830) calcareous grasslands if there is any impact of former arable field use. The study was carried out in two regions of Southern Germany with well-preserved dry grassland vegetation: the western Jurassic mountains (Kaltes Feld) and the climatically drier eastern part of Southern Germany (Kallmünz).Total number of species in the seed bank was similar in both regions, but species composition partly differed, reflecting phytogeographical differences between the regions. The total number of emerged seedlings showed a large disparity (5457 compared to 2523 seedlings/m² in Kaltes Feld and Kallmünz, respectively).Though there were differences in seed bank composition and size, we found a uniform pattern of plant traits (affiliation to phytosociological groups, Raunkiaer plant life-forms and seed longevity), which depended on the age of the grassland.The main conclusion is that seed banks in contemporary calcareous grasslands still reflect the history of former land use – in this case arable cultivation, even though it occurred a long time ago (up to 150 years). Indicators of former arable fields are germinable seeds of weeds which have persisted in the soil to the present. By contrast, weedy species are completely absent from the seed banks of ancient grasslands. Soil seed banks of recent grasslands may be of substantial conservation importance because they may store seeds of rare and endangered weed species such as Kickxia spuria, Silene noctiflora and Stachys annua, the majority of which have already gone extinct from the current vegetation of the study sites.     

Soil seed bank and aboveground vegetation within hillslope vegetation restoration sites in Jinshajing hot-dry river valley

Soil seed bank plays an important role in the composition of different plant communities, especially in their conservation. Although soil seed bank, aboveground vegetation and their relationship have been the subject of much recent attention, little is known about the size and species composition of the soil seed bank and about the aboveground vegetation in the semiarid hillslope grasslands. There is limited understanding of how these components interact to determine the importance of seed banks in regeneration. In this study, the size and species composition of a soil seed bank and aboveground vegetation have been assessed in an experiment using 36 vegetation quadrats and 108 soil samples in terrace, slope, gully, and grazing land. This land represents a range of habitats within a hillslope grassland in Jinshajing hot-dry river valley of Yunnan, China. Terrace, slope, and gully represent restored sites and grazing land typifies unrestored sites. Twenty-one taxa in the seed bank were identified with a median and median density of 7 species/m² and 5498 seeds/m², respectively, whereas in the aboveground vegetation, 19 species were observed with a median and median density of 6 species/m² and 1088 plants/m², respectively. Both seed bank density and aboveground vegetation density among grazing land, gully, slope, and terrace differed significantly. There was an absolutely high proportion of herbaceous species in the seed bank and aboveground vegetation. Gramineae predominated over both seed bank and vegetation. The most frequent seeds and plants were Bothriochloa pertusa (L.) A. Camus and Heteropogon contortus (L.) Beauv that had the highest individual number, importance value, and biomass. In the seed bank, the seeds of Bothriochloa pertusa (L.) A. Camus and Heteropogon contortus (L.) Beauv accounted for 50.68% and 33.10% of the total seeds, respectively. In the aboveground vegetation, the individual number of Bothriochloa pertusa (L.) A. Camus and Heteropogon contortus (L.) Beauv accounted for 55.66% and 29.86% of the total, respectively. The biomass of Bothriochloa pertusa (L.) A. Camus and Heteropogon contortus (L.) Beauv accounted for more than 70% of the total, reaching 206.71 g/m² and 147.76 g/m², respectively. Bothriochloa pertusa (L.) A. Camus and Heteropogon contortus (L.) Beauv had the highest importance value of 193.01 and 159.99, respectively. Density, biomass, species richness, species diversity, and evenness were the highest in terrace land, whereas these were lowest in grazing land. Similarities between the seed bank and the aboveground vegetation were moderately high and not very different among slope, gully, and terrace lands, while for grazing land, they tended to increase when the restorative stage progressed. This result contrasts with some other studies where the seed bank contributes very little to the seedling flora and the vegetative growth clearly overwhelms sexual reproduction. The hypothesis about significant functional correlation between soil seed bank density and aboveground vegetation density is conformed. Correlation between soil seed bank density and aboveground vegetation density can be described in quadratic and cubic curves. The strong similarity between the vegetation and the seed bank is attributed to a large proportion of the species Bothriochloa pertusa (L.) A. Camus and Heteropogon contortus (L.) Beauv., which are seed profusive and whose seeds have a significant viability in the ground. The high density, biomass, species richness, species diversity, and uniformity of the reclaimed site are related to the sufficiency of heat and water supplies for species establishment and growth in the site, which partly reflects the effective efforts for hillslope grassland restoration. It is believed that the efforts for vegetation restoration have altered the microhabitat conditions of the site and have provided a favorable habitat for species to establish and grow.     

The Influence of Time on the Soil Seed Bank and Vegetation across a Landscape‐Scale Wetland Restoration Project

Wicken Fen National Nature Reserve (NNR) in Cambridgeshire, U.K. is a wetland of international importance isolated in a landscape dominated by arable farming. The prospect of species extinctions within the NNR led to the creation of the Wicken Fen Vision, an ambitious project that will eventually expand the reserve boundary by the purchase and restoration of c.50 km² of arable land. We sampled three fields from each of three distinct age‐categories of restoration land (5, 15, and 60 years post‐arable), and three fields within the adjacent, undrained NNR, to determine (1) differences in seed bank composition across age‐categories, (2) relationships between restoration age, the seed bank and standing vegetation, and (3) changes in species traits across age‐categories. Historic arable management contributed to an apparent “vertical mixing” effect in the seed bank of the youngest two age‐categories, with associated and significant differences in species functional traits across the study area. Almost all plants associated with NNR vegetation were absent from restoration area seed banks and standing vegetation. Seed bank species common to all ages‐categories exhibited a bias toward moderate to high Ellenberg F (moisture) values, persistent seed banks, and lateral vegetative spread. Relatively short (c. 6 years) periods of drainage and plowing impact heavily upon seed bank diversity and soils, resulting in a lack of predrainage vegetation, even after decades of subsequent restoration adjacent to intact, species‐rich habitat. However, the seed banks of highly degraded fields can contribute toward the creation of novel wetland vegetation assemblages over time and under suitable environmental conditions.     

Soil seed bank dynamics of fire-prone wooded grassland, woodland and dry forest ecosystems in Ethiopia

In order to reveal the role of soil seed banks in vegetation recovery after fire in savanna, the spatial distribution and temporal changes in the soil seed banks of regularly burning savanna in Gambella, western Ethiopia, was studied. The seedling emergence technique was employed to determine the species composition and density of the soil seed bank of six sites ranging in fire severity from wooded grassland with frequent fires over woodland with intermediate fire frequency to forest with absence of fires. Species composition and density of seeds in the soil were compared between seasons, depths and sites with different types of standing vegetation. Fourteen plant species were recorded in the soil seed bank from the grassland and woodland sites and 6 from the dry forests; 60 % of the taxa in the soil seed bank were annuals and 40 % were perennials. The soil seed banks were largely dominated by graminoids and 48–97 % of the soil seed bank in the grasslands and woodlands was of a single grass species, Hyparrhenia confinis , which was absent from the dry forests. The soil seed pools ranged from less than 100 to 4700 seeds per m² depending upon the season. The soil seed bank of graminoids was nearly empty after the onset of the rainy season whereas seeds of broadleaved herbs and woody species able to germinate were still found after this time. Floristic composition, representation of life forms and density of seeds in soil did not correspond closely with that of the standing vegetation, but within graminoids there was a strong similarity between the soil seed bank and the standing vegetation. The current fire regime of Ethiopian savanna woodlands appears to maintain the dominance of graminoids over broadleaved herbs and woody plants both as seeds in the soil and in the standing vegetation.     

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.     

Disturbance of suburban Fagus forests by recreational activities: Effects on soil characteristics,above‐ground vegetation and seed bank

Questions: How does recreational disturbance (human trampling) affect soil characteristics, the performance of the understorey vegetation, and the density and species composition of the soil seed bank in Fagus sylvatica forests? Location: Suburban forests near Basel, northwestern Switzerland. Methods: We compared various soil characteristics and the performance of the understorey vegetation in six beech forest areas frequently disturbed by recreational activities with those in six undisturbed control areas, in spring 2003. In the same forest areas, the soil seed bank was investigated using the seedling emergence method. Samples were obtained from soil cores in January 2003. Results: We found substantial changes in soil compaction, above‐ground vegetation and in the soil seed bank due to recreational activities. In frequently visited areas, soil compaction was enhanced which caused a decrease in cover, height and species richness of both herb and shrub layers. Compared with control areas, the number of trampling‐tolerant species of the seed bank was significantly higher in disturbed areas, and total species richness tended to be higher in disturbed than in control areas. Furthermore, the similarity in species composition between the above‐ground vegetation and seed bank was significant lower in disturbed than in control areas. Conclusions: The intensive use of suburban forests for recreational activities, mainly picnicking, affects the vegetation of natural beech forests. Our study indicates that a restoration of degraded forest areas from the soil seed bank would result in a substantial change of the vegetation composition.