Seeds In Soil Research Articles

Persistence of Triticale Seed in the Soil Seed Bank

ABSTRACTSpring triticale (×Triticosecale Wittm. ex A. Camus) is being developed as a bio‐product crop for the Canadian prairies and may involve the use of genetic modification. Seed loss before or during harvest from genetically modified (GM) triticale could impact its ability to coexist with conventional crops. Experiments were conducted in Alberta, Canada, to determine if spring triticale exhibits primary dormancy relative to wheat (Triticum aestivum L.) and whether seeds persist in the seed bank. Primary dormancy was assessed for four triticale cultivars, AC Alta, Blue Aleurone, Tyndal, and AC Ultima, and AC Barrie wheat by quantifying germination weekly from anthesis to postharvest. Seed persistence was assessed for the same cultivars by placing seed‐filled mesh bags on the soil surface (0 cm) and at 2 and 12 cm burial depths. Before harvest in 2009, germinations were less than 56% for all cultivars. After harvest, AC Barrie and Blue Aleurone exhibited a short period of primary dormancy. In 2010, wet conditions were conducive to preharvest sprouting. Germinations ranged from 46 to 85% preharvest with no lingering primary dormancy postharvest. Seeds buried to 12 cm germinated readily, removing them from the seed bank within 7 mo, while 99% of seeds buried to 2 cm were nonviable 11 mo after burial. Seeds on the soil surface persisted longest; however, 99% were nonviable after 26 mo. Like wheat, triticale has little or no primary dormancy, and results from this study suggest triticale seed does not persist in the seed bank.

Primary myelofibrosis and the "bad seeds in bad soil" concept

Primary Myelofibrosis (PMF) is a chronic myeloproliferative neoplasm characterized by a clonal myeloproliferation and a myelofibrosis. The concomitant presence of neoangiogenesis and osteosclerosis suggests a deregulation of medullar stem cell niches in which hematopoietic stem cells are engaged in a constant crosstalk with their stromal environment. Despite the recently discovered mutations including the JAK2Val617F mutation, the primitive molecular event responsible for the clonal hematopoietic proliferation is still unknown. We propose that the "specificity" of the pathological process that caracterizes PMF results from alterations in the cross talk between hematopoietic and stromal cells. These alterations contribute in creating a abnormal microenvironment that participates in the maintenance of the neoplasic clone leading to a misbalance disfavouring normal hematopoiesis; in return or simultaneously, stromal cells constituting the niches are modulated by hematopoietic cells resulting in stroma dysfunctions. Therefore, PMF is a remarkable "model" in which deregulation of the stem cell niche is of utmost importance for the disease development. A better understanding of the crosstalk between stem cells and their niches should imply new therapeutic strategies targeting not only intrinsic defects in stem cells but also regulatory niche-derived signals and, consequently, hematopoietic cell proliferation.

Seed treatment and soil drench with dl-β-amino butyric acid for the suppression of Meloidogyne javanica on tomato

Due to the recent environmental concerns, increasing amounts of research have been diverted to investigating natural products for the control of nematodes. dl-β-Amino butyric acid (BABA) could play a part in limiting nematode damage to plants. In this study, different concentrations of BABA were used as soil drench and seed treatment to determine if they can control Meloidogyne javanica on tomato. In an in vitro test, BABA did not impair mobility of second-stage juveniles of the nematode but 10 and 25 mg/l concentrations reduced hatch. Both of the application methods tested (drenching soil and/or pre-treating seeds with 25 mg/l of BABA) for the treatment of nematode infested tomato plants reduced the numbers of galls and egg masses by 82 %; nematode reproduction rates on these plants were reduced to one and, compared with untreated control plants, final nematode density was decreased by nearly 87 %. Increasing BABA concentrations of the treatment solutions to 200 and 500 mg/l resulted in further reduction in nematode damage and reproduction on treated plants, although the differences between the concentrations were not significant. Compared with untreated tomato, gall and egg mass production were decreased by an average of 92 %, and reproduction rates were held below one by both the 200- and 500-mg/l BABA rates. When seeds pretreated with 25 mg/l were also soil drenched with three BABA concentrations, the effects were slightly greater than when each method was used alone. Treated plants showed slight improvement in growth and weight.

Application of silver nano-particles for protection of seeds in different soils

To investigate the possibility of using silver nano-particles for protection of a living organism, wheat seeds were nano-coated and planted. Effect of nano-treatment on seed germination and protection against fungi was compared with that of a conventional preplanting fungicide (Carboxitiram). Influence of soil conditions on the effectiveness of nano-seed treatment was also investigated. Soil conditions included different levels of nutrients, pH and moisture content. Results showed that soil conditions do not affect seed protection provided by silver nano-particles against fungi, and this effect is completely independent of soil conditions. Data analysis indicated that silver nano-particles do not reduce seed germinability. Moreover, seed protection afforded by silver nano-particles and Carboxitiram was not significantly different. Thus, nano-coating may be considered as potential preplanting fungicide. Key words: Silver nano-particles, seed treatment, preplanting fungicide.

Soil seed bank techniques for restoring wetland vegetation diversity in Yeyahu Wetland, Beijing

In recent years, wetland restoration measures have created extensive concerns globally. The theory and practice of restoring wetland vegetation diversity in wetlands through soil seed banks is discussed in this paper. A comparative study on soil seed bank and species composition in Yeyahu Wetland, Beijing, was conducted in 2007. Species and quantities of seeds from 12 sample sites were counted and measured by the seed-germinating method. After germination, 27 species belonging to 16 families and 23 genera were recorded, with an average of 11.75 species per sample site, and total average density of 24831.0individuals/m2. There were significant differences between the soil seed bank and vegetation in spring, summer and autumn, with similarity coefficients of 0.2620±0.0868, 0.2580±0.0778 and 0.1953±0.0452, respectively. Also in 2008, by using the seed bank technique, vegetation diversity was restored in a degraded wetland near Maying River of Yeyahu Wetland through the processes of spot selection, topographic surveying, water level monitoring, and vegetation management. The results showed that in the restored regions, both species and diversity coefficients of vegetation observably increased: 73.68% of the hydrophytic species we discovered were transplanted from provenance regions; germination of seeds in the soil lasted until late September; and many species completed their life history and produced new seeds to renew the seed bank. In addition, the results suggested that seed bank technique not only increased richness and multiplicity of vegetation, but also provided food chains with animal diversity in wetlands.

Burial increases seed longevity of two Artemisia tridentata (Asteraceae) subspecies

Seed longevity and persistence in soil seed banks may be especially important for population persistence in ecosystems where opportunities for seedling establishment and disturbance are unpredictable. The fire regime, an important driver of population dynamics in sagebrush steppe ecosystems, has been altered by exotic annual grass invasion. Soil seed banks may play an active role in postfire recovery of the foundation shrub Artemisia tridentata, yet conditions under which seeds persist are largely unknown. We investigated seed longevity of two Artemisia tridentata subspecies in situ by retrieving seed bags that were placed at varying depths over a 2 yr period. We also sampled naturally dispersed seeds in litter and soil immediately after seed dispersal and before flowering in subsequent seasons to estimate seed persistence. After 24 mo, seeds buried at least 3 cm below the soil surface retained 30-40% viability whereas viability of seeds on the surface and under litter declined to 0 and < 11%, respectively. The density of naturally dispersed seeds in the seed bank was highly heterogeneous both spatially and temporally, and attrition varied significantly by region. Our study suggests that Artemisia tridentata has the potential to form a short-term soil seed bank that persists longer than has been commonly assumed, and that burial is necessary for seed longevity. Use of seeding techniques that promote burial of some seeds to aid in formation of a soil seed bank may increase restoration potential.

서해안 염생식물 퉁퉁마디의 발아지속과 복원

Salicornia europaea (glasswort) is succulent, annual, halophytic plant mainly distributed throughout reclaimed land or salt marsh. It has strong tolerance to salt so that it plays the part of the pioneer species in the first succession. According to domestic and foreign studies, S. europaea contains plenty of minerals and antioxidant in the body. Since people take note of an availableness of this plant as health diet, the natural growth sites are threatened. In addition to development of salt marsh and sea shore, imprudent harvest has a bad effect to S. europaea population maintenance. To seek ways to preserve the population of this plant, we carried out the continuity of seed germination and restoration test. Seokmo Island, Daebu Island, Youngjong Island and Sudokwon landfill in Korea are selected sites for research. Result of germination continuity shows that most S. europaea seeds germinate on March but no more after July. However the germination was occurred after that time in the greenhouse. So we concluded that no germination after July is a matter of environmental condition not the number of remaining seeds. Also germination was seldom occurred in the spot where seeds production was not happened. In result of continuity test of seed germination by soil depth, germination was occurred vigorously only in top soil. From these results, we note that most S. europaea germinate in the early spring, and germination is finished by July. And this rapid germination speed makes the number of seeds in soil seed bank rare. If a large number of S. europaea in some area are harvested after July, the number of this species will dramatically decrease in that area the following year. In Seokmo Island, we carried out reintroduction experiment by sowing S. europaea seeds. On the first year, a small number of S. europaea settled and they produced seeds successfully. On April 2010, the second year, we observed many S. europaea in seed sowing sites. And we found out that plowing is more efficient than treatment sea water for settlement of S. europaea.

The invasive status of wild barley (Hordeum spontaneum Koch) in Iranian flora

The success of a weed’s biological pathway is dependent on several factors including the mechanism(s) of dispersal, longevity of seeds in the soil seed bank, adaptation to varying environmental conditions and, competitive and reproductive abilities. In Near East barley, some races can be identified as wild but in other races wild and weed forms are confounded. Wild barley has wider distribution than the wild wheat and is spread over a wide area in the East Mediterranean basin and West Asiatic countries. In the Fertile Crescent countries, Hordeum spontaneum occupies a whole array of secondary man-made habitats. Invasive weeds possess a variety of characteristics that enable them to disperse rapidly into new areas. A variety of both aboveground and belowground plant traits can be used for identifying invasive species. Wild barley has some considerable traits including high genetic variation, high allelopathic potential, high relative growth rate, root characteristics, high competitive abilities and, became an invasive species in many habitats of Iran. Further studies are essential to evaluate the other mechanism(s) of invasiveness of wild barley in alien environment. Key words: Wild barley, Hordeum spontaneum, habitat, distribution, invasive weed.

Floristic composition and spatial distribution of germinable seeds in a spruce plantation

The logging of several spruce plantations is planned for the next years in the Eifel National Park (Western Germany). To understand the ecological mechanisms of spontaneous forest regeneration that follows these impacts, it is crucial to investigate the species composition and functional diversity of the buried germinable seeds in those stands. We analysed the soil seed bank by germination method and characterised germination dynamics and distribution of seedlings throughout the samples according to a sigmoid model and cumulative curves, respectively. To compare the proportions of functional and syntaxonomical groups between seed bank and aboveground vegetation, we applied the Fisher’s exact test. Additionally, we described the spatial distribution of the species in the seed bank according to semivariograms. The studied seed bank reached a density of about 5,300 seed m−2. Most of the species detected in the seed bank are related to open vegetation, forest fringes and early successional stages of forest regeneration. In spite of a low floristic similarity between seed bank and aboveground vegetation, the functional and syntaxonomical composition is very similar. Further studies considering the distribution of seeds in the soil and the changes of the seed bank composition during the regeneration process are required.

旱直播条件下强弱化感潜力水稻根际微生物的群落结构

运用末端限制性片段长度多态性(T-RFLP)技术,以强化感水稻品种PI312777和弱化感水稻品种Lemont为材料,研究了旱直播模式下5叶期和7叶期化感水稻根际土壤微生物的组成和结构。结果显示:Hae Ⅲ和MspⅠ2种内切酶分别检测到9-87个TRFs、15-89个TRFs,各个样本的TRFs排序间存在极显著差异,表明各样本的微生物的相对丰富度存在极显著差异。用物种丰富度(<em>S</em>)、香隆指数(<em>H</em>)、Simpson多样性指数(<em>D</em>)、均匀度指数(<em>E</em>)评价了6个样本中TRFs的多样性,香隆指数最能体现2个酶切片断中TRFs的多样性,PI7中TRFs多样性最高。聚类分析和主成分分析表明旱作条件下强弱化感潜力水稻在生育前期(5叶期以前)根际微生物群落的组成与结构相似性较大,而7叶期强弱化感水稻及对照之间微生物群落差异较大,表明水稻根际微生物的组成既受生育期的影响又受水稻品种的影响。7叶期的化感水稻根际微生物呈现最大物种丰富度和香隆-威尔指数多样性,在其特有的34个菌中有7个属于粘细菌目,另外还有一些滑行菌和一些与氮循环相关的细菌等。粘细菌可能通过次生代谢产物抑制伴生杂草种子的萌发,降低杂草的密度从而提高化感水稻的化感作用潜力。;Terminal restrain fragment length polymorphism (T-RFLP) technique was employed to investigate the microbial community structure and composition in the rhizosphere of weak and strong allelopathic rice varieties directly sowing on dry paddy field at 5-leaf stage and 7- leaf stage. The results showed that 9-87 TRFs and 15-89 TRFs were detected from the soil DNA digested with two restriction enzymes Hae Ⅲ and MspⅠ, respectively. The rank-abundance of TRFs from different samples showed extremely significant difference, indicating that relative abundance of rhizosphere bacteria was markedly different. The diversity indices including species abundance(<em>S</em>), Shannon-wiener diversity index(<em>H</em>), Pilow diversity index(<em>D</em>) and evenness index(<em>E</em>) were used to analyse the diversity of TRFs in 6 samples. The analysis of correlation coefficients among species indices showed that Shannon-wiener diversity index was the best one for the invesitigation of the species diversity. The Shannon-wiener diversity in the sample of PI7 was the highest compared with those in the others. The cluster analysis and principle analysis suggested the similarity among the 3 samples of 5-leaf stage was greater than that of 7- leaf stage. Especially, the three samples of 7-leaf stage were separated by not only principal component Ⅰbut also principal component Ⅱ, which implicated that the composition and structure of soil microorganism community could be regulated by both growth stage of rice and rice variety. The Shannon-wiener diversity index and species richness of PI7 were the highest in all samples, and 34 genera were special in PI7, in which 7 genera belonged to myxobacteria. Some sliding bacteria and N-fixing bacteria were also found in those special genera of PI7. Secondary metabolites of Myxobacteria might improve the allelopathic potential of allelopathic rice by inhibiting germination of weed seeds in soil seed bank and decreasing the density of weeds in the field of rice.

The effect of tillage simplifications and mineral fertilisation level on the number and distribution of weed seeds in soil

In the present paper, results of a study on the effect of a reduction in the number of ploughings in a crop rotation on the seed weed bank in the soil are presented. The study was carried out in the second and fourth year of a crop rotation (potato- spring wheat- pea- winter wheat). A reduction in the number of ploughings to three in the crop rotation decreased weed infestation of the plough layer, whereas when only one ploughing was made there was clearly more weed diaspores in the soil than after plough tillage. In the first period of the study, the mineral fertilisation level did not differentiate the weed seed bank in the soil, whereas after the end of the rotation its significant increase was noted as a result of more intensive fertilisation. In all the experimental treatments, diaspores of &lt;i&gt;Chenopodium album&lt;/i&gt;, &lt;i&gt;Viola arvensis&lt;/i&gt;, &lt;i&gt;Galinsoga&lt;/i&gt; sp. and &lt;i&gt;Apera spica-venti&lt;/i&gt; occurred in greatest numbers.

Spatio-Temporal Distribution of Nests and Influence of Ant (Formica cunicularia Lat.) Activity on Soil Property and Seed Bank after Revegetation in the Tengger Desert

In Shapotou, northeast of the Tengger Desert in China, Formica cunicularia Lat. proliferated after mobile sand dune stabilization by artificial revegetation. In the present paper, the anthill properties of F. cunicularia after sand stabilization were systematically investigated along a chronosequence. The soil properties and soil seed banks in the anthill and adjacent soils without anthills were also examined. The results showed that the revegetation age, landform, and their interactions significantly affected the anthill density, anthill coverage, and soil turnover capacity of F. cunicularia. The longer the dunes were stabilized, the more ant nests proliferated in the dunes. More nests were located in the hollow and windward slopes than in the dune top and leeward slopes. Soil organic matter, total and available N, P, and K, electrical conductivity, as well as soil water content were all significantly higher in the nests than in the adjacent soils without anthills. The soil seed bank in the anthill was much greater than in the adjacent soil for both moss- and algal-crusted soils. The current research suggested that the occurrence of F. cunicularia after mobile sand dune stabilization greatly influenced both soil properties and soil seed bank.

Protection of melon plants against Cucumber mosaic virus infection using Pseudomonas fluorescens biofertilizer

This study was carried out to characterize a virus causing severe mosaic, yellowing, stunting and leaf deformation on melon ( Cucumis melo L.), and evaluate the capacity of Pseudomonas fluorescens as biofertilizer to improve plant growth and restrict the accumulation of the virus in the plant. The virus was identified as an isolate of Cucumber mosaic virus (CMV) by means of symptoms on indicator plants, serological characteristics using double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA) and immunochromatography, and molecular weight of coat protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The source of the virus infection was also determined by the same means. P. fluorescens was used as seed treatment and soil applications. The seedling grown from bacterial treated seeds in non-treated soil and those grown from non-treated seeds in bacterial treated soil were mechanically inoculated with CMV extract at the primary leaf stage. Two proteins representing CMV coat protein appeared on 10% SDS-PAGE of 24 and 26 kD. It has been found that 9 of 35 weed plants harbor CMV. Treatment seeds and soil with P. fluorescens suspension induced significant reduction in virus accumulation in the plants as proved by absorbance values of ELISA- reactions. Minimum absorbance values of ELISA reactions at 405 nm were found to be 0.160 and 0.298 for seed and soil treatments, respectively when compared with 1.190 for samples from CMV-inoculated plants (control). The inhibition activity of P. fluorescens against CMV continued to be significant up to 20 days of virus inoculation with absorbance values of ELISA-reactions (0.460 and 0.930) for seed and soil treatment, respectively. The results indicate that P. fluorescens is able to induce systemic resistance against CMV in the plants. Key words : Cucumber mosaic virus (CMV), Cucumis melo , melon, plant growth promoting microorganisms (PGPM), Pseudomonas fluorescens , viral diseases management.

Tipos de substratos para germinação de sementes de palmeira- real-australiana (Archontophoenix alexandrae H. Wendl. & Drude)

Os objetivos deste trabalho foram avaliar o desempenho germinativo de sementes de palmeira-australiana em diferentes substratos e estabelecer a granulometria e intensidade de umedecimento adequado. A semeadura foi realizada com quatro repetições de 25 sementes em solo, areia, rolo de papel e em vermiculita de diferentes granulometrias: mícron (0,15-0,20 mm), superfina (0,21-0,30 mm), fina (0,30-0,50 mm) e média (1,19-0,50 mm), umedecidas com 0,5; 1,0; 1,5; e 2,0 vezes o seu peso em água. O teste de germinação foi conduzido a 20-30 °C, avaliando-se a primeira contagem do teste aos sete dias após a semeadura e, semanalmente, a germinação (plântulas normais) até os 35 dias, quando foram contabilizadas, também, as plântulas anormais e as sementes mortas. Calcularam-se o tempo médio e frequência relativa de germinação. A vermiculita mícron umedecida com uma vez o seu peso em água apresentou o melhor desempenho como substrato para o teste de germinação de sementes de palmeira-real-australiana, por possibilitar a máxima germinação das sementes (90%) e velocidade de germinação, demandando tempo médio de 15,3 dias nesse processo.

Effect of using co- inoculums bacteria (Bradyrhizobium japonicum and Pseudomonas puteida ) to the improvement environment and Soybean growth and yield

The present study was carried out to regulate the microbial activity in soil environment to be suitable for soybean so as the increase the activity of rhizobia fertelizering forming nodules and increasing the microbial inoculum activity through providing plant nutrients. A pot experiment was conducted by culturing soybean seeds (gesa-65)in sandy loam soil. Tow isolates of Bradyrhizobium japonicum and Pseudomonas puteida were used after evaluating their activities in the laboratory as co- inoculums in addition to the treatment of a single B. japonicum as well as a control treatment . Results have showd the ability of two isolates to produce IAA and dissolve phosphate compounds. P. puteida was able to produce NH3 and HCN as well as sidrophores and inhibit the growth of F. oxysporum mycelium. The co- inoculums of the two isolates were efficient for activity the highest rate of plant growth 93%, and nodules formation estimated after month of plant growth 42 nodule 90% activity. Also, the two isolates improved the nutrient status N, P ( 20.3,210 mg/kg soil) They increase the microbial density that dissolves phosphates and nitrogen fixation in the plant environment (5.26 ,5.32 Log cfu/g).The activity of the two isolates in soil environment was increasing the dry weight of the roots, vegetables, number of nodules , yields( 22.12 ,74.32 ,80 , 85.3 / plant), P and N conteats and protein percentage 36.25%.

Edaphic factors influence the longevity of seeds in the soil

A thorough understanding of the rate of depletion of ungerminated seeds in soil is necessary to understand and model the population dynamics of many plant species. To assess how edaphic conditions influence seed survival over time a long-term field study was set up. Mesh bags of seeds of 12 species were buried under 12 contrasting semi-natural and grassland habitats and retrieved at intervals over 10 years. Seed survival and viability were assessed through germination trials and chemical staining. There were clear differences in the rate of depletion of ungerminated seed between species and also differences in the variability of this measure between habitats. Seed survival was longer in soils with a higher pH, lower moisture content and lower soil C:N. Soil characteristics need to be taken into account within studies of plant populations that depend on regeneration from seed, particularly for species where seed survival is sensitive to edaphic conditions. Ignoring this influence of the dynamics of seeds under different soil conditions may have a serious impact on the success of population modelling.

Advanced lentil lines screened for resistance to Fusarium oxysporum f. sp. lentis under greenhouse and field conditions

Fusarium oxysporum f. sp. lentis is the most important pathogen of lentil plants, and most areas under lentil cultivation are reported to have a fusarium wilt disease background. The plants are infected in the seedling stage and later stages of their development. Fusarium wilt disease, which has appeared at high incidence rates during recent years, has caused sharp drops in the yield, especially in Moghan, in the northwest of Iran. Forty-five isolates of the pathogen were collected from different regions of the country with two isolates from ICARDA in the summer of 2008 and identified using Nelson’s key. The pathogenicity of the collected isolates was studied on a sensitive line (ILL 4605) under greenhouse conditions and significant differences in pathogenicity were found among them. The most pathogenic isolates from three provinces, East Azerbaijan (EA 30), Ardebil (Ar 3) and Khorasan (Kh 45), were selected and used in screening of 55 developed lines under greenhouse and field conditions. In the greenhouse, test plants were inoculated by immersing root tips in spore suspension and sowing seeds in pre-infested pot soil. Field tests were carried out in a naturally highly infested farm. At all stages, the plant response to the disease was based on the percentage of dead plants. Cluster analyses of the greenhouse and field data led to the selection of three lines (81S15, FLIP2007-42 L and FLIP2009-18 L) that were resistant under greenhouse and field conditions.

Seed germination cues and the importance of the soil seed bank across an environmental gradient in the Serengeti

Soil seed banks are an important source of new individuals for many plant populations and contribute to future genetic variability. In general, the size and persistence of soil seed banks is predicted to be greater where growth occurs in unpredictable pulses, where opportunities for disturbance‐related recruitment are frequent and where the probability of recruitment failure is high. In savanna ecosystems, characterized by disturbance from fire and unpredictable water availability, soil seed banks should be relatively important sources of recruitment. However, the few studies conducted in savannas are inconclusive about the importance of soil seed banks and, more specifically, how seed banks should change across environmental gradients. We determined the number of viable seeds in the soil seed bank across savanna‐grasslands in the Serengeti, an ecosystem characterized by frequent fire and seasonal drought. Soils were exposed to a combination of smoke and heat, cues which may be required to break seed dormancy in such ecosystems. Our a priori expectation was to observe large seed banks in regions characterized by seasonal drought and comparatively smaller seed banks in regions of higher moisture availability and high fire frequencies. In contrast to our hypothesis, seed germination increased strongly with precipitation and fire frequency. In addition, there was a significant interaction effect between fire and rainfall: low rainfall sites with frequent fire had greater seed germination than low rainfall sites with low fire frequency. Moreover, in laboratory experiments, heat had a negative, smoke a positive effect on final seed germination numbers. Together, these findings suggest that fire may be a key factor in driving herbaceous seed bank dynamics in tropical savannas.

Effects of Long-Term Trampling on the Above-Ground Forest Vegetation and Soil Seed Bank at the Base of Limestone Cliffs

Exposed limestone cliffs in central Europe harbor a highly divers flora with many rare and endangered species. During the past few decades, there has been increasing recreational use of these cliffs, which has caused local environmental disturbances. Successful restoration strategies hinge on identifying critical limitations. We examined the composition of aboveground forest vegetation and density and species composition of seeds in the soil seed bank at the base of four limestone cliffs in mixed deciduous forests that are intensively disturbed by human trampling and at four undisturbed cliffs in the Jura Mountains in northwestern Switzerland. We found that long-term human trampling reduced total aboveground vegetation cover at the base of cliffs and caused a significant shift in the plant-species composition. Compared with undisturbed cliffs, total seed density was lower in disturbed cliffs. Human trampling also altered the species composition of seeds in the soil seed bank. Seeds of unintentionally introduced, stress-tolerant, and ruderal species dominated the soil seed bank at the base of disturbed cliffs. Our findings indicate that a restoration of degraded cliff bases from the existing soil seed bank would result in a substantial change of the original unique plant composition. Active seed transfer, or seed flux from adjacent undisturbed forest areas, is essential for restoration success.

Seed persistence in the soil on eroded slopes in the hilly-gullied Loess Plateau region, China

AbstractThe soil seed-bank is an important component of vegetation dynamics. Its presence affects both ecosystem resistance and resilience. A persistent seed-bank is especially important in disturbed habitats and harsh environments. In the hilly-gullied Loess Plateau region, serious soil erosion causes decreases in soil water capacity and constrains vegetation recolonization. A stable and long-term persistent soil seed-bank is necessary for natural vegetation recolonization. We used an integrated measure of the depth distribution of seeds in the soil and the seasonal dynamics of soil seed-banks to analyse the persistence of seeds in soil and to investigate the correlation of seed longevity with seed size/shape and the species' life history. The results showed a significant tendency for small seeds and seeds of annuals/biennials to persist longer in soil than large seeds and seeds of perennials. However, seed shape was not related to persistence. The main dominant speciesArtemisia scoparia, Lespedeza davurica, Heteropappus altaicus, Stipa bungeana, Artemisia gmelinii, and Bothriochloa ischaemun in the different successional stages in this region can form a persistent and stable soil seed-bank. The pioneer species A. scoparia is especially significant because it can form a large, long-term, persistent seed-bank. These species can play a role in the recolonization of the eroded abandoned slope lands by vegetation.