The soil seed bank and understorey regeneration in Eucalyptus regnans forest,Victoria

Abstract The soil seed bank and its relation to the extant vegetation in a Eucalyptus regnans F. Muell. forest in the Central Highlands of Victoria were examined. The average seed density was 430 germinable seeds m^?2 to a depth of 2 cm. There was a polynomial regression relationship between the density and species richness of seeds in soil and forest age (0. 6–54 years). Species richness was not significantly different among soil depths (0- 2 , 2- 5 , 5–10 and 10–20 cm) in the forest stand of 54 years old. More seeds germinated from the 5–10 cm depth than from the other depths. Forbs accounted for 73% of the total germinable seeds and there was no germination of E. regnans. The number of species, particularly woody plant species, germinating from the soil seed bank were significantly lower than in the extant vegetation. However, almost all species present in the soil seed bank were present in the vegetation. The soil seed bank provides an important source for the rapid regeneration of understorey vegetation following clear-cutting and slash-burning in the E. regnans forest. The rapid understorey establishment may play an important role in protecting soil from erosion, in nutrient conservation, replacement and redistribution. The soil seed bank may also be a necessary source of maintaining genetic diversity in the forest over the long term.     

The effect of stand age and microhabitat on soil seed banks in Mediterranean Aleppo pine forests after fire

Soil samples from three microhabitats (gaps, beneath shrubs and beneath trees) in five stands of various post-fire ages (6–55 years) were collected in an east Mediterranean Aleppo pine Pinus halepensis forest. Total germinable seed bank densities varied between 300 and 1300 seeds per m². Herbaceous taxa were the major constituents of the germinable seed bank in gaps, regardless of stand age. Perennials were the major components beneath shrubs in all stands except the youngest stand where herbaceous species were the major components in all microhabitats. Important tree and shrub species (e.g., Pinus halepensis, Quercus calliprinos, Pistacia lentiscus, Phillyrea latifolia) of the mature pine forest were not an important component of the soil seed bank and therefore, little resemblance was observed between the above-ground plant species composition and soil seed bank composition. This is consistent with the fact that these species regenerate by resprouting rather than by germination from the seed bank. Both microhabitats and forest-stands, which were of different ages, contributed to the variation in taxa richness, germinable seed density and diversity among samples. The effect of small-scale spatial heterogeneity (among microhabitats) was much more pronounced. In contrast to other studies, species richness, species diversity, and density of seed banks did not decrease with post-fire age. Moreover, stand age was a poor predictor for these attributes of the soil seed bank in an Aleppo pine forest. The heterogeneity plays an important role in conservation and management of this ecosystem.     

内蒙古锡林郭勒克氏针茅退化草原土壤种子库特征

以内蒙古锡林郭勒地区克氏针茅(Stipa krylovii)草原不同退化等级群落为对象,研究克氏针茅退化草原可萌发土壤种子库特征.结果表明,随着草原退化程度的增加,不论是土壤总种子库还是持久土壤种子库,组成和密度均明显下降, 重度和极度退化草原土壤总种子库密度下降至仅为轻度退化草原的46.8%和11.1%.代表土壤总种子库的4月份取样, 轻度、中度、重度和极度退化草原各样地0～9 cm土壤种子库密度分别为2800、1278、1311和311粒·m-2;代表持久土壤种子库的6月底取样,4个样地土壤种子库密度分别为1667、967、334和167粒·m-2.多数植物土壤种子库主要分布在0～6 cm土层,各样地种子库密度随土壤深度的增加而减少,轻度、中度、重度和极度退化草原4月份0～6 cm土层种子库分别占总种子库(0～9 cm)的98.4、96.5、95.8 和85.7%.不同退化等级草原地上植被与土壤种子库的Sorensen相似性指数介于0.24～0.48.     

Microhabitat variations and seed bank-vegetation relationships in a desert wadi ecosystem

Due to extreme variability in patterns of rainfall, plant seed banks are an important component of desert habitats. Here I report on effects of standing vegetation and three different microhabitats (channel, bank and terrace) on the soil seed bank of a desert wadi ecosystem in the Eastern Desert of Egypt. A total of 450 soil samples at 45 stands were collected to represent the different wadi microhabitats. The germinable seed bank was estimated by controlled counts of seedling emergence. The floristic composition, functional properties and diversity of the soil seed bank, as well as its similarity with the standing vegetation varied among wadi microhabitats. Such variation could be attributed to differences in disturbance intensity among microhabitats (terrace < bank < channel) and variation of soil factors along the microtopographic gradient. Channel showed the highest species richness and size of soil seed bank, followed by bank and then terrace. Moreover the Shannon index of diversity of the seed bank and its similarity with standing vegetation were significantly greater in both channel and bank microhabitats than in terrace. At the level of plant functional groups, number of seeds of annuals was higher in both channel and bank than in terrace. Shrubs were more abundant in seed banks of channel compared to terrace. The size and species richness of seed bank were increased with the total plant cover, annual/perennial ratio and species richness of the standing vegetation.     

Comparison of soil seed banks of habitats distributed along an altitudinal gradient in northern Iran

In this study we investigated the variations in soil seed banks along an altitudinal gradient in the Alborz mountains, Iran, covering three habitats from lower to upper altitudes: forest, forest-subalpine grassland ecotone and subalpine meadow. In each habitat from 1850 to 2400 m, 20 quadrats were established along four transects, and the above-ground vegetation and the germinable seed banks were determined. Results show that the similarity between seed bank and vegetation was lowest in the ecotone located at intermediate altitudes. Together with the contrasting highest density and species diversity of seeds at these altitudes, the ecotonal role of this habitat was confirmed.We found evidence that lower altitudes could act as storage for seeds of some species growing at higher altitudes; the role of the ecotone was more prominent as a reserve for the meadow plant seeds than the role of the forest as a reserve for seeds of the meadow and ecotone habitats. Soil seed banks, particularly from the ecotone, can be used for restoring vegetation in some degraded sites.     

Afromontane old-field vegetation: secondary succession and the return of indigenous species

South‐west Uganda primarily holds afromontane forests within three protected areas: Mgahinga Gorilla National Park, Echuya Forest Reserve and Bwindi Impenetrable National Park. All forests contain portions of old‐field vegetation. The central question of this study, then, is whether and how natural regeneration of afromontane vegetation would take place. A successional pathway consisting of nine plant communities was found for the first 2 years after cessation of agricultural use. A return of afromontane species despite of an initial dominance of neophytes, a diversification of life form spectra and a growing importance of endozoochory with time belonged to the conspicuous characteristics of this secondary succession. To obtain an insight into the role of birds and buffaloes as possible vectors for seed input, I examined their faeces with regard to germinable seeds. Both, bird faeces, as well as buffalo faeces contained germinable seeds originating from the forest flora. Thus, animal dispersal from the forest into the regenerating zones could be documented. The regeneration potential of the soil‐seed bank seems to be limited in its time scale, and only an initial regeneration capacity could be found. A further progressive succession into a secondary afromontane forest depends on an input of diaspores from undisturbed forest sites. Zoochory appears to be one of the most important dispersal mechanisms.     

Seed banks in Danish deciduous forests: species composition, seed influx and distribution pattern in soil

Samples of soil from six forest stands of different age and composition were collected, and the seedlings emerging during germination experiments were recorded Total seed bank densities varied between 2230 and 15,630 seeds m⁻² The seed bank size was positively correlated with the yearly seed influx, which constituted from 400 to 2720 seeds m⁻² Juncus effusus dominated the seed banks with generally 2000 to 3300 seeds m⁻², to exceptionally 10820 seeds m⁻² Seeds of Rubus idaeus, Betula pubescens and Carex spp were also abundant in the soil Similar numbers of species were present in the seed banks and vegetation, but only 7-48% were species in common Anemochorous species were more frequent in soil than above-ground, while zoochorous species were rare in soil but abundant in the vegetation A measure of the occurrence of seeds in relation to soil depth was designed Seeds of species with short-term survival in soil (e g Anemone nemorosa, Epilobium angustifolium, Oxalis acetosella and Stellaria holostea) were confined to the top soil, while many well known long-term survivors (e g Carex piluhfera, Poa annua, Rubus idaeus and Stellaria media) were found predominantly deep in the soil The horizontal distribution of seeds of herbaceous species forming short-term seed banks was largely random, while seeds of herbs capable of long-term survival in soil were significantly aggregated Except for one old and species-poor site, the dormant flora indicated generally high levels of disturbance in the past     

Soil seed bank characteristics in Cameroonian rainforests and implications for post-logging forest recovery

The soil seed bank is considered as an important component for resilience of climacic vegetation. Whereas several related studies have been conducted in Asian, American and some African tropical forests, no investigation has ever been conducted in Central African rainforests, especially in logged forests where the soil seed bank could contribute to regeneration of timber of trees species. We studied the soil seed bank characteristics in relation to the standing vegetation in three Cameroonian forest zones with different disturbance regimes. There was no significant difference between sites in terms of density of the seed bank; the average mean density was 87.6 seeds m⁻². But dissimilarities of the floristic compositions between sites were quite high. Overall, seeds came from 43 species including three commercial tree species. Whereas the seedlings emerging from soil samples mostly came from weedy and short-lived pioneer species, climax species predominated in the extant vegetation, leading to a very weak similarity between soil seed flora and the surrounding vegetation: Sorensen's index ranged from 3.5 to 7.6%. Canopy openness could significantly affect the species richness of soil seed stocks but not the seed density. These results show that the soil seed bank contribution to the resilience of mature tropical forests is low. In particular, very few timber tree species could benefit from soil seed stocks for their regeneration. Therefore, the development of enrichment techniques including use of the soil seed bank as a source of tree regeneration in such a context would be irrelevant.     

Soil seed banks in dry Afromontane forests of Ethiopia

Abstract. The soil seed bank was investigated in four dry Afromontane forests of Ethiopia. At least 167 plant species were identified in the 0–9 cm soil layer with total densities ranging between 12 300 and 24 000 seeds/m². Herbs were represented with the largest numbers of species and seeds in the seed bank, while the contribution of tree species was generally low. The overall vertical distribution of seeds was similar at all sites with the highest densities occurring in the upper three cm of soil and gradually decreasing densities with increasing depth. Relatively high densities also occurred in the litter layer. There were large differences in depth distribution between species, suggesting differences in seed longevity. A large number of species in dry Afromontane forests evidently store quantities of seeds in the soil and this is in contrast to the situation in most tropical rain forests, dry lowland forests and savannas, where both the number of seeds and the number of species are relatively small. It is possible that the strongly seasonal and unpredictable climate of this region may have selected for high levels of dormancy, and that herb regeneration is associated with small scale disturbance. The fact that most of the dominant tree species do not accumulate seeds in the soil suggests that their regeneration from seed would be unlikely if mature individuals disappeared. Most tree species have relatively large seeds and poor long-distance dispersal; this implies that restoration of Afromontane forests after destruction would be difficult. Since there is a diverse seed bank of the ground flora, this component of the vegetation would have a better chance of reestablishing. However, because most cleared forest land is used for agricultural crop production, it is probable that the seed bank will be depleted in only a few years. Therefore, the future of the Afromontane forest flora seems to depend on the successful conservation of the few fragments of remaining natural forest.     

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

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

Seed bank composition and above-ground vegetation in response to grazing in sub-Mediterranean oak forests (NW Greece)

We investigate the persistent soil seed bank composition and its relation to the above-ground flora of grazed and non-grazed sub-Mediterranean deciduous oak forests of NW Greece. Twenty-eight taxa were recorded in the soil seed bank and 83 taxa (70 taxa in plots of seed bank sampling) in the above-ground vegetation. The dominant tree species and many woodland species found in the above-ground vegetation were absent from the soil seed bank. Similarity between the soil seed bank and the above-ground vegetation decreased with grazing, and grazing led to a decrease of species richness in above-ground vegetation and soil seed bank. Beta diversity of vegetation among grazed and among non-grazed plots did not differ, but was significantly higher between grazed and non-grazed areas. Beta diversity of the soil seed bank declined with grazing. When applying classification tree and logistic regression analyses, non-grazed forest sites are clearly differentiated by the presence of Phillyrea latifolia, Euphorbia amygdaloides and Brachypodium sylvaticum. PCA ordination of above-ground species composition reflected a gradient from sites grazed by ruminants to non-grazed sites, but no clear structure was detected in the seed bank.     

Soil seed bank in different habitats of the Eastern Desert of Egypt

The floristic composition and species diversity of the germinable soil seed bank were studied in three different habitats (desert salinized land, desert wadi, and reclaimed land) in the Eastern Desert of Egypt. Moreover, the degree of similarity between the seed bank and the above-ground vegetation was determined. The seed bank was studied in 40 stands representing the three habitats. Ten soil samples (each 25 × 20 cm and 5 cm depth) were randomly taken per stand. The seed bank was investigated by the seedling emergence method. Some 61 species belonging to 21 families and 54 genera were identified in the germinable seed bank. The recorded species include 43 annuals and 18 perennials. Ordination of stands by Detrended Correspondence Analysis (DCA) indicates that the stands of the three habitats are markedly distinguishable and show a clear pattern of segregation on the ordination planes. This indicates variations in the species composition among habitats. The results also demonstrate significant associations between the floristic composition of the seed bank and edaphic factors such as CaCO₃, electrical conductivity, organic carbon and soil texture. The reclaimed land has the highest values of species richness, Shannon-index of diversity and the density of the germinable seed bank followed by the habitats of desert wadi and desert salinized land. Motyka’s similarity index between the seed bank and the above-ground vegetation is significantly higher in reclaimed land (75.1%) compared to desert wadi (38.4%) and desert salinized land (36.5%).     

Can the soil seed bank contribute to revegetation of the drawdown zone in the Three Gorges Reservoir Region?

The drawdown zone of the Three Gorges Reservoir Region was assumed to be completely formed in 2009 and the water level would range from ~145 m in flood season (summer) to ~175 m during non-flood season (winter). The soil seed bank is an important propagule source for vegetation restoration. In order to evaluate the potential of the soil seed bank to revegetate the drawdown zone of this region, we examined the quantitative relationships between the germinable soil seed bank and the established vertical and horizontal vegetation patterns. A total of 45 soil samples at four sites was collected to examine seed bank density, species richness, and composition using the seedling-emergence method. Forty-five species (from 20 families) germinated from the soil seed bank, and the average seed density was 4578 m⁻². The seed bank was dominated by annual plants, suggesting reestablishment of some above-ground species was plausible. However, most established woody plants and perennials were absent from the seed bank indicating a low probability of reestablishment for non-annuals through the seed bank. Thus, due to low species compositional similarity to extant vegetation and the dominance of annual plants, the soil seed bank had a low potential to restore pre-dam vegetation in the drawdown zone of the Three Gorges Reservoir Region, but its potential as a propagule source should be considered regarding the management of the drawdown zone for vegetation cover.     

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.     

Soil seed bank and regeneration potential on eroded hill slopes in the Kondoa Irangi Hills,central Tanzania

Abstract. The soil seed bank of the severely eroded Kondoa Irangi Hills, Tanzania was studied in order to determine the seed density and composition and to establish the relationship between seed bank and standing vegetation. The area had not been grazed for 15 yr prior to the study. A recently grazed area was used for comparison. The seed bank density (at 0 - 5 cm depth) ranged from 344 to 915 8 seeds/m² in the dry season and 172 to 5107 seeds/m² in the wet season. The seed bank was very heterogeneous, both spatially and temporally, and it showed significant variation in size and composition in both sampling periods. The species similarity between the seed bank and the above-ground vegetation in all plots was low (Sørensen's index = 0.00–0.44). The highest similarity was found in the recently grazed area. The seed bank was dominated by annuals and by early successional species. It is concluded that re-vegetating the hill slopes with woody vegetation by using the seed bank will be difficult because seeds of woody species were not found in the soil.     

Seed Stores for Restoration of Species-Rich Shrubland Vegetation Following Mining in Western Australia

The extreme species richness of native shrubland vegetation (kwongan) near Eneabba, Western Australia, presents a major problem in the restoration of sites following mineral sand mining. Seed sources available for post-mining restoration and those present in the native kwongan vegetation were quantified and compared. Canopy-borne seeds held in persistent woody fruits were the largest seed source of perennial species in the undisturbed native vegetation and also provided the most seeds for restoration. In undisturbed vegetation, the germinable soil seed store (140–174 seeds · m^?2) was only slightly less than the canopy-borne seed store (234–494 seeds · m^?2), but stockpiled topsoil provided only 9% of the germinable seeds applied to the post-mining habitat. The age of stockpiled soil was also important. In the three-year-old stockpiled topsoil, the seed bank was only 10.5 seeds · m^?2 in the surface 2.5 cm, compared to 56.1 to 127.6 seeds · m^?2 in fresh topsoil from undisturbed vegetation sites. In the stockpiled topsoil, most seeds were of annual species and 15–40% of the seeds were of non-native species. In the topsoil from undisturbed vegetation, over 80% of the seeds were of perennial species, and non-native species comprised only 2.7% of the seed bank. Additional seeds of native species were broadcast on restoration areas, and although this represented only 1% of the seed resources applied, the broadcast seed mix was an important resource for increasing post-mining species richness. Knowledge of the life-history characteristics of plant species may relate to seed germination patterns and assist in more accurate restoration where information on germination percentages of all species is not available.     

洮河上游紫果云杉群落土壤种子库特征及其与地上植被的关系

该研究以甘肃洮河国家级自然保护区大峪沟林区(TH)、冶力关林区(YLG)、尕海 则岔国家级自然保护区则岔林区(GZ)的紫果云杉(Picea purpurea)天然林群落为研究对象,通过样地调查与萌发实验,分析洮河上游紫果云杉群落土壤种子库特征,以揭示洮河上游紫果云杉群落土壤种子库特征及与地上植被的关系,为紫果云杉群落恢复和管理提供依据。结果表明：(1)3个林区土壤种子库共萌发27科45属50种植物,种子库密度在958~1 129粒/m²之间,草本植物是构成研究区土壤种子库的主体。(2)3个林区紫果云杉群落土壤种子库垂直结构明显,物种数及种子密度随土层的加深呈减少趋势。(3)3个林区地上植被物种数大于土壤种子库物种数,相似性系数在0.15~0.23之间,表现为极不相似性;土壤种子库的多样性指数除Pielou指数高于地上植被外,Margalef指数、Shannon Wiener指数、Simpson指数均低于地上植被。研究认为,洮河上游紫果云杉群落土壤种子库以草本植物为主,乔木和灌木的储量较小,特别是建群种紫果云杉的储量较小;地上植被和土壤种子库之间相互的贡献力较低,仅依靠紫果云杉林土壤种子库进行自然恢复,远不能缓解现阶段紫果云杉林退化的问题,因此需开展人工育苗、造林等措施来促进紫果云杉的更新与发展。     

普洱市周边地区4种土地利用类型土壤种子库特征

通过对云南普洱市周边地区次生季风常绿阔叶林、针阔混交林、人工更新形成的针叶林及茶园等4种土地利用类型的野外调查及土壤种子库的萌发实验,探讨其土壤种子库的密度大小、物种丰富度和组成及与地上植被的关系。结果表明:干扰强度与频度不同导致土地利用类型之间土壤种子库密度与物种丰富度存在较大差异,土壤种子库密度大小顺序为:针叶林(248.67±116.86)粒·m-2>针阔混交林(186.00±43.27)粒·m-2>次生季风常绿阔叶林(107.33±16.48)粒·m-2>茶园(51.67±10.17)粒·m-2;茶园土壤种子库物种丰富度要显著低于其他类型。4种土地利用类型土壤种子库生活型组成差异极显著,主要以草本植物组成,以菊科与禾本科占优势;针阔混交林的草本植物种子密度最多,非森林的原生物种是草本植物的主要组成;针叶林外来物种的种子密度要显著高于其他类型,紫茎泽兰(Eupatorium adenophorum)是其主要组成。土壤种子库与地上植被的相似性系数较低,其大小顺序为:次生季风常绿阔叶林(0.175)<针阔混交林(0.176)<针叶林(0.215)。     

冷蒿草原土壤可萌发种子库特征及其对放牧的响应

（１）采用萌发试验法对内蒙古冷蒿（Ａｒｔｅｍｉｓｉａ ｆｒｉｇｉｄａ）草原土壤种子特征及其在不同放牧压力下的变化进行了研究。（２）冷蒿草原可萌发种子库由４种多年生禾草,１１种种多年生杂草及３种１年生植物所组成。（３）每样中的可萌发种子是变化于４５到３０５之间,平均１０２／样。多年生禾草、多年生杂类草及１年生植物的土壤中种子量分别占总可萌发种子库的４６．５７％、５１．９６％和１．５７％。多年和禾 草     

Soil seed bank in a patchy vegetation of coastal sandy plains in southeastern Brazil

Large seed banks have been found in tropical dry forests and also in habitats with high seasonality in rainfall. However, patchily structured vegetation could induce great spatial variation in the seed bank. We characterized the seed bank in a patchy vegetation of restinga, a common type of coastal vegetation found in the Atlantic forest biome. We also evaluated whether there is any spatial variation between the litter and soil layer, bare sand, and the edge and center of vegetation patches with distinct species dominance. We found 104 seeds/m² in the seed bank using a 5‐cm‐depth sampling. Seven out of 16 species found in the restinga seed bank germinated; two of these were found in the early stages of vegetation patches. We found a higher number of seeds at the edge than in the center of vegetation patches. However, there were no significant differences in the number of seeds in the seed bank between the litter and soil layer, and between vegetation patches with distinct species dominance. Bare sandy soils had lower seed bank densities than vegetation patches. A small seed bank size might be explained by the low proportion of seeds from herbaceous and woody species, which are pioneers in the Atlantic forest. However, seed bank might play an important role in the early stages of the successional process, due to the occurrence of the few species that are able to colonize new young vegetation patches.