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Responses to climate change have often been found to lag behind the rate of warming that has occurred. In addition to dispersal limitation potentially restricting spread at leading range margins, the persistence of species in new and unsuitable conditions is thought to be responsible for apparent time-lags.Soil seed banks can allow plant communities to temporarily buffer unsuitable environmental conditions, but their potential to slow responses to long-term climate change is largely unknown. As local forest cover can also buffer the effects of a warming climate, it is important to understand how seed banks might interact with land cover to mediate community responses to climate change.We first related species-level seed bank persistence and distribution-derived climatic niches for 840 plant species. We then used a database of plant community data from grasslands, forests and intermediate successional habitats from across Europe to investigate relationships between seed banks and their corresponding herb layers in 2763 plots in the context of climate and land cover.We found that species from warmer climates and with broader distributions are more likely to have a higher seed bank persistence, resulting in seed banks that are composed of species with warmer and broader climatic distributions than their corresponding herb layers. This was consistent across our climatic extent, with larger differences (seed banks from even warmer climates relative to vegetation) found in grasslands.Synthesis. Seed banks have been shown to buffer plant communities through periods of environmental variability, and in a period of climate change might be expected to contain species reflecting past, cooler conditions. Here, we show that persistent seed banks often contain species with relatively warm climatic niches and those with wide climatic ranges. Although these patterns may not be primarily driven by species' climatic adaptations, the prominence of such species in seed banks might still facilitate climate-driven community shifts. Additionally, seed banks may be related to ongoing trends regarding the spread of widespread generalist species into natural habitats, while cool-associated species may be at risk from both short- and long-term climatic variability and change. Responses to climate change have often been found to lag behind the rate of warming that has occurred. In addition to dispersal limitation potentially restricting spread at leading range margins, the persistence of species in new and unsuitable conditions is thought to be responsible for apparent time-lags. Soil seed banks can allow plant communities to temporarily buffer unsuitable environmental conditions, but their potential to slow responses to long-term climate change is largely unknown. As local forest cover can also buffer the effects of a warming climate, it is important to understand how seed banks might interact with land cover to mediate community responses to climate change. We first related species-level seed bank persistence and distribution-derived climatic niches for 840 plant species. We then used a database of plant community data from grasslands, forests and intermediate successional habitats from across Europe to investigate relationships between seed banks and their corresponding herb layers in 2763 plots in the context of climate and land cover. We found that species from warmer climates and with broader distributions are more likely to have a higher seed bank persistence, resulting in seed banks that are composed of species with warmer and broader climatic distributions than their corresponding herb layers. This was consistent across our climatic extent, with larger differences (seed banks from even warmer climates relative to vegetation) found in grasslands. Synthesis. Seed banks have been shown to buffer plant communities through periods of environmental variability, and in a period of climate change might be expected to contain species reflecting past, cooler conditions. Here, we show that persistent seed banks often contain species with relatively warm climatic niches and those with wide climatic ranges. Although these patterns may not be primarily driven by species' climatic adaptations, the prominence of such species in seed banks might still facilitate climate-driven community shifts. Additionally, seed banks may be related to ongoing trends regarding the spread of widespread generalist species into natural habitats, while cool-associated species may be at risk from both short- and long-term climatic variability and change.

Aim\ud \ud Climate and land use are key determinants of biodiversity, with past and ongoing changes posing serious threats to global ecosystems. Unlike most other organism groups, plant species can possess dormant life‐history stages such as soil seed banks, which may help plant communities to resist or at least postpone the detrimental impact of global changes. This study investigates the potential for soil seed banks to achieve this.\ud \ud \ud \ud Location\ud \ud Europe.\ud \ud \ud \ud Time period\ud \ud 1978–2014.\ud \ud \ud \ud Major taxa studied\ud \ud Flowering plants.\ud \ud \ud \ud Methods\ud \ud Using a space‐for‐time/warming approach, we study plant species richness and composition in the herb layer and the soil seed bank in 2,796 community plots from 54 datasets in managed grasslands, forests and intermediate, successional habitats across a climate gradient.\ud \ud \ud \ud Results\ud \ud Soil seed banks held more species than the herb layer, being compositionally similar across habitats. Species richness was lower in forests and successional habitats compared to grasslands, with annual temperature range more important than mean annual temperature for determining richness. Climate and land‐use effects were generally less pronounced when plant community richness included seed bank species richness, while there was no clear effect of land use and climate on compositional similarity between the seed bank and the herb layer.\ud \ud \ud \ud Main conclusions\ud \ud High seed bank diversity and compositional similarity between the herb layer and seed bank plant communities may provide a potentially important functional buffer against the impact of ongoing environmental changes on plant communities. This capacity could, however, be threatened by climate warming. Dormant life‐history stages can therefore be important sources of diversity in changing environments, potentially underpinning already observed time‐lags in plant community responses to global change. However, as soil seed banks themselves appear, albeit less, vulnerable to the same changes, their potential to buffer change can only be temporary, and major community shifts may still be expected.

The article presents an overview of archaeobotanical research on artificial dwelling mounds, so-called 'terps', in the northern-Netherlands. A total of 40 studies carried out over the past 40 years is evaluated. The vegetation diversity in the area as well as the differences with the present marsh are studied. Seriation, Principal Component Analysis and Sorensen similarity indices are used to assess the diversity of both individual samples and sites. For comparison with the present marshes, an index based on the TMAP vegetation typology was defined. Based on these methods, a selection of the individual samples was analyzed phytosociologically. It is found that all samples represent a mixture of vegetation types, but that the salt marsh species are a constant factor. The variation in the sample composition is not related to their dating, except for some of the latest samples that reflect the earliest endikements. Great similarity to the present marshes is found, but the analysis also testifies of a landscape profoundly disturbed by human activities throughout history.

Plant traits – the morphological, anatomical, physiological, biochemical and phenological characteristics of plants and their organs – determine how primary producers respond to environmental factors, affect other trophic levels, influence ecosystem processes and services and provide a link from species richness to ecosystem functional diversity. Trait data thus represent the raw material for a wide range of research from evolutionary biology, community and functional ecology to biogeography. Here we present the global database initiative named TRY, which has united a wide range of the plant trait research community worldwide and gained an unprecedented buy-in of trait data: so far 93 trait databases have been contributed. The data repository currently contains almost three million trait entries for 69 000 out of the world's 300 000 plant species, with a focus on 52 groups of traits characterizing the vegetative and regeneration stages of the plant life cycle, including growth, dispersal, establishment and persistence. A first data analysis shows that most plant traits are approximately log-normally distributed, with widely differing ranges of variation across traits. Most trait variation is between species (interspecific), but significant intraspecific variation is also documented, up to 40% of the overall variation. Plant functional types (PFTs), as commonly used in vegetation models, capture a substantial fraction of the observed variation – but for several traits most variation occurs within PFTs, up to 75% of the overall variation. In the context of vegetation models these traits would better be represented by state variables rather than fixed parameter values. The improved availability of plant trait data in the unified global database is expected to support a paradigm shift from species to trait-based ecology, offer new opportunities for synthetic plant trait research and enable a more realistic and empirically grounded representation of terrestrial vegetation in Earth system models.

International audience; The ongoing decline of many plant species in Northwest Europe indicates that traditional conservation measures to improve the habitat quality, although useful, are not enough to halt diversity losses. Using recent databases, we show for the first time that differences between species in adaptations to various dispersal vectors, in combination with changes in the availability of these vectors, contribute significantly to explaining losses in plant diversity in Northwest Europe in the 20th century. Species with water- or fur-assisted dispersal are over-represented among declining species, while others (windor bird-assisted dispersal) are under-represented. Our analysis indicates that the 'colonization deficit' due to a degraded dispersal infrastructure is no less important in explaining plant diversity losses than the more commonly accepted effect of eutrophication and associated niche-based processes. Our findings call for measures that aim to restore the dispersal infrastructure across entre regions and that go beyond current conservation practices.

The objective of the study was to characterize annual ryegrass seed population dynamics, managed for natural re-sowing, in no til systems in rotation with soybean, in different chronosequences An area was cultivated for two years with soybean, left as fallow land for the next two years and then cultivated again with soybean for the next two years. The four chronosequences represented different management periods, two with soybean (6 and 8 years old) and the other two resting (3 and 9 years old). Soil samples were taken every month during one year and divided into two depths (0-5 and 5-10 cm). Vegetation dynamics were also evaluated (number of plants, inflorescences and seedlings). Soil seed bank (SSB) dynamics showed structural patterns in time, with a "storage period" in summer, an "exhausting period" during autumn and a "transition period" in winter and spring. Pasture establishment by natural re-sowing was totally dependent on the annual recruitment of seeds from the soil. The influence of the management practices on the SSB was more important than the number of years that these practices had been implemented. Places where soybean was sown showed the largest SSBs. Most of the seeds overcame dormancy and germinated at the end of the summer and beginning of the autumn, showing a typically transitory SSB, but with a small proportion of persistent seeds O estudo objetivou a caracterização da dinâmica de populações de sementes de azevem anual em manejo de revegetação, em um sistema de plantio direto em rotação com soja, em diferentes seqüências. A soja foi cultivada por dois anos e cultivada novamente depois de dois anos de pousio. As quatro seqüências representaram diferentes períodos de manejo, dois deles com soja (6 e 8 anos) e os outros dois restantes (3 e 9 anos). Amostras de solos foram tomadas a cada mês, durante um ano, em duas profundidades (0-5 e 5-10 cm). A dinâmica de vegetação foi também avaliada (numero de plantas, inflorescências e plântulas). A dinâmica do banco de sementes do solo (SSB) mostrou padrão estrutural no tempo, com um período de armazenamento no verão, um período de exaustão durante o outono e um período de transição no inverno e primavera. O estabelecimento de pastagem por revegetação natural 'e' totalmente dependente do banco de sementes do solo. A influência das praticas de manejo no SSB e mais importante do que o numero de anos que estas praticas tem sido implementadas. Locais onde a soja foi cultivada mostraram maior SSB. A maior parte das sementes teve sua dormência quebrada e germinaram no final do período de verão e começo do outono, mostrando um típico SSB transitório, mas com pequena proporção de sementes persistentes.

1. An international group of scientists has built an open internet data base of life-history traits of the Northwest European flora (the LEDA-Traitbase) that can be used as a data source for fundamental research on plant biodiversity and coexistence, macro-ecological patterns and plant functional responses.2. The species-trait matrix comprises referenced information under the control of an editorial board, for ca. 3000 species of the Northwest European flora, combining existing information and additional measurements. The data base currently contains data on 26 plant traits that describe three key features of plant dynamics: persistence, regeneration and dispersal. The LEDA-Traitbase is freely available at www.leda-traitbase.org.3. We present the structure of the data base and an overview of the trait information available.4. Synthesis. The LEDA Traitbase is useful for large-scale analyses of functional responses of communities to environmental change, effects of community trait composition on ecosystem properties and patterns of rarity and invasiveness, as well as linkages between traits as expressions of fundamental trade-offs in plants.

Questions: 1. Which plant traits and habitat characteristics best explain local above-ground persistence of vascular plant species and 2. Is there a trade-off between local above-ground persistence and the ability for seed dispersal and below-ground persistence in the soil seed bank?Locations: 845 long-term permanent plots in terrestrial habitats across the Netherlands. Methods: We analysed the local above-ground persistence of vascular plants in permanent plots (monitored once a year for ca. 16 year) with respect to functional traits and habitat preferences using survival statistics (Kaplan-Meier analysis and Cox' regression). These methods account for censored data and are rarely used in vegetation ecology.Results: Local above-ground persistence is determined by both functional traits (especially the ability to form long-lived clonal connections) and habitat preferences (especially nutrient requirements). Above-ground persistence is negatively related to the ability for dispersal by wind and to the ability to accumulate a long-term persistent soil seed bank ('dispersal through time') and is positively related to the ability for dispersal by water.Conclusions: Most species have a half-life expectation over 15 years. which may contribute to time lags after changes 'in habitat quality or -configuration ('extinction debt'). There is evidence for a trade-off relationship between local aboveground persistence and below-ground seed persistence, while the relationship with dispersal in space is vector specific. The rate of species turnover increases with productivity.

1. Restoration of salt marshes on previously reclaimed land provides an excellent opportunity to study plant colonization and subsequent development of salt-marsh vegetation. Insight into the process of salt-marsh development can guide the design, implementation and evaluation of salt-marsh restoration schemes and help determine appropriate management strategies. 2. We evaluated the process of salt-marsh restoration at a species- and plant-community level and investigated how the sequence of species establishment is related to site suitability, availability of the target species in the local and regional species pools and dispersal traits. 3. It took approximately 5 years for species diversity in the restoration site to become similar to a local reference marsh. The annual species Salicornia spp. and Suaeda maritima colonized and reached maximum abundance first. Perennial species (Puccinellia maritima, Aster tripolium, Spartina anglica, Spergularia media, Atriplex portulacoides and Limonium vulgare) only started to colonize or increase notably in abundance after 3 years of restoration. 4. Plant composition at the highest elevation of the restoration site developed from an annual Salicornia community into a Puccinellia maritima salt marsh, which was similar to the local reference marsh. After 8 years, the lower elevations were still covered by annual Salicornia salt marsh despite the potential for the development of a Puccinellia community. 5. Salt tolerance appeared to be much more important in explaining the sequence of species establishment than the availability of the species in the local or regional species pools or dispersal traits. 6. Synthesis and applications. The prospect of salt-marsh restoration after de-embankment is good, with target species establishing spontaneously and vegetation succession taking place. Because most salt-marsh species are dispersed over short distances, it is important that a well-developed salt marsh is adjacent to the restoration site. The rate of salt-marsh development and species diversity appears to be affected mainly by surface elevation. Proper elevation in relation to tidal inundation is therefore a prerequisite for the successful restoration of salt-marsh vegetation after de-embankment.

This Special Feature includes contributions on dataprocessing of large ecological datasets under the heading ecoinformatics. Herewith the latter term is now also established in the Journal of Vegetation Science. Ecoinfomatics is introduced as a rapid growing field within community ecology which is generating exciting new developments in ecology and in particular vegetation ecology. In our field, ecoinformatics deals with the understanding of patterns of species distributions at local and regional scales, and on the assemblages of species in relation to their properties, the local environment and their distribution in the region. Community ecology using ecoinformatics is related to bioinformatics, community ecology, biogeography and macroecology.We make clear how ecoinformatics in vegetation science and particularly the IAVS Working Group on Ecoinformatics has developed from the work of the old Working Group for Data Processing which was active during the 1970s and 1980s. Recent developments, including the creation of TURBOVEG and SynBioSys in Europa and VEGBANK in the USA, form a direct link with these pioneer activities, both scientifically and personally.The contributions collected in this Special Feature present examples of seco-infeveral types of the use of databases and the application of programmes and models. The main types are the study of long-term vegetation dynamics in different cases of primary and secondary succession and the understanding of successional developments in terms of species traits.Among the future developments of great significance we mention the use of a variety of different large datasets for the study of the distribution and ecology and conservation of rare and threatened species.

Most data mining techniques have rarely been used in ecology. To address the specific needs of scientists analysing data from a plant trait database developed during the LEDA project, a web-based data mining tool has been developed. This paper presents the DIONE data miner and the project it has been developed in. It addresses the nature of plant trait data from a data mining perspective and points out problems that arise when preparing data for this process. The availability of a large amount of high quality data is an essential prerequisite for successful data mining. To ensure this, a software aided reviewing process has been integrated into the LEDA Traitbase system. The process enables third-party contributors to easily commit their data to LEDA, while assuring adherence of the data to the LEDA standard. The paper concludes with information about data mining results on plant trait data achieved so far and gives an outlook on the applicability of data mining to the fields of ecology. (c) 2006 Elsevier Ltd. All rights reserved.

Increased insight into the factors that determine the importance of dispersal limitation on species richness and species composition is of paramount importance for conservation and restoration ecology. One way to explore the importance of dispersal limitation is to use seed-sowing experiments, but these do not enable the screening of large sets of species and habitats. In the present paper we present a complementary approach based on comparing small plots with larger regions with regard to species composition and distribution of functional traits. We developed a GIS tool based on ecological and geographical criteria to quantify species pools at various spatial scales. In this GIS tool, containing floristic, large databases, phytosociological and functional information are exploited. Our premise is that differences in the nature of the species in local and regional species pools with regard to functional traits can give important clues to the processes at work in the assembly of communities. We illustrate the approach with a case study for mesotrophic hay meadows (Calthion palustris). We tested the effects of differences in frequency in the local Habitat Species Pool and differences in dispersal and persistence traits of species on local species composition. Our results show that both species pool effects and functional traits affect the probability of occurrence in small plots. Species with a high propagule weight have, given the frequency in the Local Habitat Species Pool, a lower probability of occurrence in small plots. The probability of local occurrence, however, is increased by the ability to form a persistent soil seed bank and by adult longevity. This provides support for the view that the degree of dispersal limitation is dependent on the degree of spatial isolation of the focal site relative to source populations and moreover that species inherently differ in the degree to which dispersal limitation is a limiting factor for local occurrence.

Contains fulltext : 60338.pdf (Publisher’s version ) (Closed access) 1 Local plant communities can only function within a metacommunity context if they are connected by appropriate dispersal vectors, accommodating the transport of propagules between sites. The capacity for long-distance dispersal may be a key factor in the survival of local populations, especially in fragmented landscapes, and hence may have a large impact on local species composition. Dispersal vectors with a large efficiency for long-distance dispersal included in this study are: water, wind, large mammals and birds. 2 We tested the hypothesis that variation in dispersal traits across plant communities is related to the position of the communities along major environmental gradients. This hypothesis was tested for (i) separate long-distance dispersal vectors and (ii) multiple dispersal vectors (the number of potential long-distance dispersal vectors per species). 3 To quantify linkages between dispersal traits and environmental gradients, we coupled a data base containing dispersal attributes with another data base, containing 40 000 local vegetation descriptions aggregated into 123 plant communities. For each dispersal vector, the proportions of species that have access to this vector per community (weighted trait scores) were projected along three major environmental gradients: soil moisture, nutrient availability and light availability. 4 The potential importance of individual dispersal vectors showed clear differences along the three environmental gradients, with the greatest differences along the light availability gradient. The differences in dispersal traits probably reflect environmental constraints on the availability or efficiency of individual dispersal vectors. 5 The ability to be dispersed by multiple dispersal vectors is a common phenomenon in most plant communities (an average of 2.15 vectors per species). The mean number of potential long-distance dispersal vectors per species increases with light availability. This probably implies that plant communities differ in their response to both habitat fragmentation and habitat restoration. 6 Despite differences in trait spectra among communities, all dispersal syndromes are represented in nearly all communities. An important consequence of this complementarity in dispersal traits is that species within the same community may experience different connectivity. 7 The results emphasize the need for dispersal models based upon multiple dispersal vectors that explicitly include parameters for habitat characteristics.

Summary 1 The diversity and abundance of viable diaspores trapped at the downstream end of a 15-km lowland stream were quantified and related to five potentially predicting variables: species’ occurrence in the species pool, distance to the nearest stand and the life-history traits seed buoyancy, seed production and plant height. 2 From 126 samples, 106 614 individuals of vascular plants developed, 95.8% from vegetative diaspores and 4.2% from seeds. Among these plants, three free-floating, 12 submerged, 22 emergent (aquatic) and 70 riparian (semi-aquatic and terrestrial) species were recorded, respectively, accounting for 24.3%, 71.9%, 1.2% and 2.6% of the total number of viable diaspores trapped. 3 Of the free-floating, submerged and emergent species, 100%, 98.9% and 23.7% of the diaspores were vegetative, respectively, whereas it was 2.9% for riparian species. 4 Diaspores of 79% of the total number of aquatic species and 40% of riparian species observed in the established vegetation were trapped. Minimal dispersal distances ranged from 0 to 6 km. 5 Multiple regression analysis conducted for submerged species, showed that 71% of the variation in the diaspore pool could be predicted by occurrence of species in the vegetation. For emergent species, seed production and occurrence of species explained 54% of the variation, seed production being most important. Mean seed buoyancy of emergent species was higher than that of the other groups. For riparian species, seed production, occurrence and buoyancy explained 48% of the variation in the diaspore pool. Seed production per plant was the most important variable. Linear regression revealed a negative relationship between distance and abundance of the diaspore pool for submerged and riparian species. 6 We conclude that the occurrence of species in the species pool is a significant predictor for the dispersal of free-floating and submerged aquatics that rely on vegetative propagation. Seed production and buoyancy are of additional importance with regard to emergent aquatics. Riparian species with a limited terrestrial dispersal capacity may largely extend their range by hydrochory. That is, if they produce large amounts of (small) seeds and provided that these can reach the water body. Buoyancy and high frequency and abundance in the established vegetation promote this dispersal capacity as well.

There is confusion in the ecological literature between seed dormancy and persistence in soil. Some ecologists seem to assume that dormancy is necessary for persistence, while others imply that dormancy and persistence are virtually synonymous. Here, we show that there is no close relationship between dormancy and persistence and, incidentally, that conventional methods of investigating soil seed banks underestimate the persistence of species with dormant seeds. The confusion appears to arise from the concept of ‘enforced dormancy’, which is not genuinely dormancy at all, and would be eliminated if ecologists adopted the definition of dormancy employed by physiologists. Dormancy is a characteristic of the seed, not of the environment, the degree of which defines the conditions required to make the seed germinate.

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

Dispersal and life span of individual plant species within five plant communities were assessed to obtain a characterization of these communities in this respect. Such a characterization is important in the context of restoration and maintenance. The most frequent species of five communities were ranked in eight classes according to their level of seed dispersal capability, their seed bank formation (dispersal in time and space) and their individual life span. In the communities, all eight classes were found, but communities differed in the distribution of the species over the classes. A theoretical framework was constructed to use the level of specialization of plant species in terms of dispersal in space and time, and life span, to define the characteristics of safe site dynamics within communities. Following simple rules, the relative reliability of the occurrence of safe sites in space and time was defined. After that, the relative reliability of the habitat was linked to the best fitting combination of trait specialization level. Having defined this link, communities could be characterized in a comparative way by their level and pattern of reliability of the opportunities for recruitment in space and time.The meaning of the coexistence of a range of trait combinations in one community was discussed. It was postulated that habitat reliability can explain this by assuming that the habitat of the community is part of a larger system, or consists of several "subsystems". These insights need to be considered in nature conservation. Succession and also specializations beyond the scope of dispersal and life span may influence the occurrence of species in a seemingly unfit habitat (for instance the occurrence of semi parasitic annuals in a community of perennials, because they use the perennial root system of other species). Finally, the meaning of safe site reliability in space and time in the context of restoration of communities was discussed. The reliability in space and time may be different today from that of the past, which restricts the feasibility of restoration of communities.

1 Changes in the species composition of the soil seed bank were determined in a dry and a more species-rich wet chronosequence. Each sequence represented a 25-year hayfield succession following cessation of fertilizer application in the Drentse A Nature Reserve (NL). where the vegetation has been studied since 1972. 2 The number of seeds of many late successional species showed a significant increase during succession with only two characteristic late species present in the seed bank of the early stage of each series. Most of the early successional species showed a decrease in the number of seeds, which paralleled their relative frequency within the vegetation. Overall, seed density and species diversity of the seed bank was higher in the wet than the dry chronosequence. 3 Mean values for seed longevity were calculated for each successional phase in each series using a published seed bank data base, When based simply on the presence of species, the seed longevity index decreased significantly during the wet-series succession in both surface and deeper seed banks and in the vegetation. When based on the relative frequency of species present, the index decreased significantly in both series but only in the surface seed bank and the vegetation. 4 Comparison with data for an ancient undisturbed wet hay meadow in England suggests that seed longevity of hayfield species is generally low. Similarity between seed bank and established vegetation was low in both the undisturbed British meadow (only 47%) and in the relatively young Dutch study sites (c. 50%). 5 The soil seed bank is unlikely to determine hayfield succession in the Drentse A Nature Reserve, since the composition of the soil seed bank tended to follow that of the above-ground vegetation. Increases in plant species richness following the cessation of fertilizer application, the main goal of restoration management, therefore depend to a large extent on an influx of the seeds of most species from outside the site.

The soil seed bank composition was determined at four sites in the dune slack 'Koegelwieck' on the Dutch Wadden Sea island of Terschelling. At three different sites in the slack, where sod-cutting experiments down to the mineral sand had been carried out, the established vegetation and seed bank were assessed after 5, 9 and 39 yr of undisturbed development, respectively. In addition, a fourth site in the slack was investigated, where vegetation development had proceeded for 80 yr since plant colonization of bare soil and where nowadays a vegetation dominated by Calamagrostis epigejos and Salix repens occurs. Together these four sites can be regarded as a chronosequence of dune slack formation.Clear time sequences were detected in the seed bank data. Many late successional species showed a significant increase in the number of seeds during the succession. Some of the early successional basiphilous pioneer species such as Anagallis minima, Centaurium littorale, Littorella uniflora, Radiola linoides and Samolus valerandi, showed either a decrease during the time of succession or an optimum in the vegetation while remaining present in the seed bank in low but detectable numbers. They could, therefore, play a role in re-establishment of the vegetation after sod-cutting. One of the target species, Schoenus nigricans, established within a few years after removal of the sod. However, no seeds of this species have been detected in the soil below either of the successional stages. Based on the species disappearance from the established vegetation and based on the independent data of Thompson et al. (1997) an estimation of seed longevity could be made for several Red List species of wet dune slacks.

1. We investigated the vertical distribution of seeds in the soil, using data from nine studies in five European countries. We discovered significant correlations between seed shape and distributio ...

1. Effects of high nutrient input on the longevity and viability of buried seed are examined. Seeds of 17 fen-meadow species were buried in nylon mesh bags at four sites in the Netherlands and one site in Great Britain in plots to which N, P, K fertilizers are applied. Prior to burial germination tests were conducted on the seeds of each species. This paper describes the results of the viability tests on the seeds that were exhumed after one and 2 years of burial. 2. The percentage of seeds that germinated after 1 year of burial was significantly lower than the pre-burial percentage for the majority of the species. After 2 years of burial the germination percentage further decreased. A few species, such as the Carex species, did, however, show an increase in germination percentage indicating that the burial conditions allowed dormancy controls to be broken. 3. Differences in the edaphic conditions between the sites appeared to affect germination percentages after 1 year of burial. A difference in germination response between sites was observed for Carex acutiformis, Filipendula ulmaria and Lychnis flos-cuculi. 4. A significantly higher germination percentage was found at the Great Britain site for F. ulmaria in the phosphate treatment compared with the potassium treatment and the control after 1 year of burial. In contrast to many literature assessments no significant effects of fertilizer application was found after 2 years. 5. For all sites, except one in the Netherlands, the total number of seeds that germinated was lower in 1996 than in 1995.

I Using the data in a recently published seed bank database for north-west Europe, we describe how a species' seed bank behaviour can be characterized by a single 'longevity index', and investigate how representative the information in the database is of the north-west European flora. We also test the hypotheses that seeds of short-lived species are more persistent than those of long-lived species, and long-lived seeds are characteristic of species living in disturbed habitats. 2 The data are not representative of the north-west European flora as a whole; they are a fair reflection of a research effort that has been largely directed towards grassland and arable weeds. Data for rare species, non-agricultural habitats in general and wetlands, rocky habitats and native woodland in particular, are scarce or absent. 3 Annuals and biennials almost always have more persistent seeds than related perennials, and this difference is most striking when, as in Anagallis arvensis and Aphanes arvensis, the short-lived species have moved well away from the 'core' habitat of the family. Confamilial monocarps and polycarps do not differ consistently in seed mass. 4 Gradients of habitat disturbance are accompanied by predictable changes in seed persistence, which are themselves often (but not always) accompanied by parallel shifts in seed size. These results suggest that increasing habitat disturbance (i.e. increasing density-independent mortality) always selects for increased seed persistence, confirming both theory and previous analyses. However, increased seed persistence is not always associated with reduced seed size. This is because persistence depends not only on seed size, but on other traits, many of them physiological. In many habitats the probability of seed burial is strongly linked to seed size and shape, but in arable habitats cultural practices have broken this link.

Many studies carried out during these last few years have focused on the factors influencing plant diversity in species-rich grasslands. This is due to the fact that these ecosystems, among the most diversified in temperate climates, are extremely threatened; in some areas, they have almost disappeared. The re-establishment of these habitats implies to know the living conditions of the associations to be recreated. Very often, the typical species of these communities have become so rarefied that the seed bank or the seed rain are not sufficient to recreate the plant community. Most of the time, to achieve the restoration of these communities, they have to be totally recreated by sowing. For the restoration or the maintenance of the community, the soil chemical characteristics have also to be appropriate or if not modified. This research tends to establish a relation between some soil chemical factors and the plant diversity of a great number of stations. This research has illuminated the relationship between soil extractable phosphorus and potassium and plant diversity. Over 5 mg of phosphorus per 100 g of dry soil (acetate + EDTA extraction), no station containing more than 20 species per 100 m(2) has been found. The highest number of species is found below the optimum content of the soil for plant nutrition (5-8 mg P/100 g). Concerning the potassium, the highest number of species is found at 20 mg/100, a value corresponcing to an optimum content of the soil for plant nutrition. High potassium contents, in opposition to phosphorus contents, are thus compatible with high values of diversity. Other factors (i.e. pH, organic matter, total nitrogen and calcium) do not show so clearly a relation with plant diversity. Excess of N-NO3 is known for its negative effect on the diversity of plant communities. In these environments, apart from the atmospheric deposits which can be important in some areas, N-NO3 is derived mainly from the symbiotic fixation of atmospheric nitrogen by legumes as well as from the mineralization of the organic matter of the soil. It is possible that, when in small quantities, the available soil phosphorus could be a limiting factor of the N-NO3 supply by these two sources. In this hypothesis, nitrogen would remain the main element limitating plant diversity but its availability would be controlled by phosphorus.

In plant leaves, resource use follows a trade-off between rapid resource capture and conservative storage. This “worldwide leaf economics spectrum” consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf construction and light-interception borne by plants. We conducted a broad-scale analysis of the evolutionary history of LMA across a large dataset of 5401 vascular plant species. The phylogenetic signal in LMA displayed low but significant conservatism, that is, leaf economics tended to be more similar among close relatives than expected by chance alone. Models of trait evolution indicated that LMA evolved under weak stabilizing selection. Moreover, results suggest that different optimal phenotypes evolved among large clades within which extremes tended to be selected against. Conservatism in LMA was strongly related to growth form, as were selection intensity and phenotypic evolutionary rates: woody plants showed higher conservatism in relation to stronger stabilizing selection and lower evolutionary rates compared to herbaceous taxa. The evolutionary history of LMA thus paints different evolutionary trajectories of vascular plant species across clades, revealing the coordination of leaf trait evolution with growth forms in response to varying selection regimes. Fil: Flores, Olivier. Centre d’Ecologie Fonctionnelle et Evolutive; Francia. Université de la Réunion; Francia Fil: Garnier, Eric. Centre d’Ecologie Fonctionnelle et Evolutive; Francia Fil: Wright, Ian J.. Macquarie University. Department of Biological Sciences; Australia Fil: Reich, Peter B.. University of Minnesota. Department of Forest Resources and Institute on the Environment; Estados Unidos. University of Western Sydney. Hawkesbury Institute for the Environment; Australia Fil: Pierce, Simon. University of Milan. Department of Plant Production; Italia Fil: Diaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Pakeman, Robin J... James Hutton Institute; Reino Unido Fil: Rusch, Graciela M.. Norwegian Institute for Nature Research; Noruega Fil: Bernard Verdier, Maud. Centre d’Ecologie Fonctionnelle et Evolutive; Francia Fil: Testi, Baptiste. Centre d’Ecologie Fonctionnelle et Evolutive; Francia Fil: Bakker, Jan P.. Community and Conservation Ecology Group; Países Bajos Fil: Bekker, Renee M.. Community and Conservation Ecology Group; Países Bajos Fil: Cerabolini, Bruno. Universita degli Studi dell’Insubria; Italia Fil: Ceriani, Roberta. Centro Flora Autoctona; Italia Fil: Cornu, Guillaume. Department Environment and Societies Research Unit Forests and Societies; Francia Fil: Cruz, Pablo. Institut National de la Recherche Agronomique; Francia Fil: Delcamp, Matthieu. Department Environment and Societies Research Unit Forests and Societies; Francia Fil: Dolezal, Jiri. Academy of Sciences of the Czech Republic. Institute of Botany; República Checa Fil: Eriksson, Ove. Stockholm University. Department of Botany; Suecia Fil: Fayolle, Adeline. Department Environment and Societies Research Unit Forests and Societies; Francia Fil: Freitas, Helena. University of Coimbra. Centre for Functional Ecology; Portugal Fil: Golodets, Carly. Faculty of Life Sciences. Department of Molecular Biology and Ecology of Plants; Israel Fil: Gourlet Fleury, Sylvie. Department Environment and Societies Research Unit Forests and Societies; Francia Fil: Hodgson, John. The University. Department of Archaeology; Reino Unido Fil: Brusa, Guido. Universitá degli Studi dell’Insubria; Italia Fil: Kleyer, Michael. Carl von Ossietzky University of Oldenburg. Landscape Ecology Group; Alemania Fil: Kunzmann, Dieter. Carl von Ossietzky University of Oldenburg. Landscape Ecology Group; Alemania Fil: Lavorel, Sandra. Universite Joseph Fourier. Laboratoire d’Ecologie Alpine and Station Alpine Joseph Fourier; Francia Fil: Papanastasis, Vasilios. Aristotle University of Thessaloniki. Laboratory of Rangeland Ecology; Grecia Fil: Perez Harguindeguy, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Vendramini, Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina Fil: Weiher, Evan. University of Wisconsin Eau Claire. Department of Biology; Estados Unidos

The biodiversity of the open dune landscapes in the Netherlands is gradually declining due to less intensive use of the dunes, increased deposition of atmospheric nitrogen (5–10 fold increase between 1939 and 1981), and a growing need of drinking water for urban areas that led to desiccation of dune wetlands . Since 1990, numerous restoration projects have been carried out in the coastal area to curb the loss of biodiversity in the dune areas. Grazing was reintroduced in the dry dunes, the technique for drinking water production was modified, rewetting and removing of acidified top soils was applied in interdunal wetlands, and on a small-scale aeolian dynamics was re-initiated to stimulate sand blowing in the dunes. Restoration measures in the dune slacks were generally more successful than in the dry dunes. Most typical, dune slack species returned when hydrological conditions were appropriate. In the dry dunes a few typical dune species returned after restoration measures. Grass encroachment and rapid growth of shrubs could not be stopped by only grazing, due to too high availability of nutrients in the soil and many typical dune species have become so rare that they apparently could not reach the restoration areas.

1. Trait-based approaches are increasingly used to obtain an insight into the functional aspects of plant communities. Since measuring traits can be time-consuming, large international databases of plant traits are being compiled to share the effort. From these databases, average trait values are often extracted per species by averaging trait values of individuals over multiple populations and habitats. However, the accuracy of such aggregated information from regional databases as a surrogate for on-site measurements has seldom been tested. 2. For the local species pool (aggregated at the habitat-level) and the plant communities on the plots (aggregated at the community-level), we quantified how accurately trait values for each species measured at the plot (plot scale) and those averaged per species and site (site scale) can be estimated from those retrieved from a North-west-European trait database. We analysed three widely used plant traits, canopy height (CH), leaf dry matter content (LDMC) and specific leaf area (SLA), of species occurring in a wet meadow and a salt marsh. 3. Database values more accurately predicted traits aggregated at the habitat-level than those aggregated at the community-level. In addition, traits with lower plasticity, such as LDMC, were more accurately predicted by database values. The performance of database values also depended upon the habitat studied, for example, habitat-level SLA values were accurately predicted by database values in the wet meadow but inaccurately predicted in the salt marsh. 4. Synthesis. This study reveals that the accuracy of traits retrieved from a database depends on the level of aggregation (lower at community-level), the trait (lower in plastic traits) and the habitat type (lower in extreme habitats). For studies focussing on processes mainly acting at the site scale (e.g. trait–environment relationships), traits retrieved from a regional database and filtered according to habitat will probably lead to good results. Whereas studying processes acting at the plot scale (e.g. niche partitioning), requires the additional effort of measuring traits on-site.

The role of seed dispersal by mowing machinery in the invasion into a hayfield under restoration management was investigated for the annual hemiparasite Rhinanthus angustifolius (C.C. Gmelin). Therefore, all plants of R. angustifolius in a hayfield were removed before seed production in 1994. As R angustifolius seeds rarely survive for more than 1 year this would almost entirely prevent establishment of seedlings in 1995. In August 1994 the hayfield was divided into three parts. Under fair-weather conditions two of these parts were mown by a clean tractor disk mower combination and a tractor disk mower combination previously contaminated with R angustifolius seeds, respectively. The third part was mown under rainy conditions by a contaminated caterpillar mower. In June 1995 all established R. angustifolius plants within the three parts were mapped. In both parts mown by contaminated machinery more plants of R angustifolius were found as compared to the part mown with clean machinery. The part mown under wet-weather conditions by the caterpillar mower, in particular, contained many established plants of R angustifolius. The results suggest that spatial patterns of establishment are induced by machinery. The conclusion of the experiment is that mowing machinery acted as a dispersal agent of R angustifolius seeds in 1994. This probably applies to other hayfield species as well. Machinery may therefore play a major role in seed dispersal within the nature reserve, enhancing the speed of succession within hayfields. The circumstances under which the experiment took place did not allow us to conclude on separate effects of machinery type or weather conditions on seed dispersal. However, both effects may exist.

Soil seed bank composition along a gradient from dry alvar grassland to Juniperus shrubland.

The interest was the seed longevity dynamics of annual ryegrass in natural conditions as an important tool to explain its dynamics in no tillage systems used in the South of Brazil. The species is commonly managed for natural re-sowing and, in this way, allows cattle grazing with reduced costs during the winter time. In February of 2003, twenty bags of nylon screen containing sterilised soil with 100 seeds in each were randomly buried in the field, 5 cm deep. Around every three or four months, four sacks were exhumed. Seeds were counted and tested using germination and tetrazolium tests.The seeds showed high primary dormancy, which was overcome very fast. After 108, 226, 326, 565 and 732 days of burial there were no significant differences as the secondary dormancy of the seeds that did not germinate in autumn was not high. The last exhumation period was significantly different from the others due to the strong decay on seed viability. As few seeds remained viable after 732 days, the soil seed bank was classified as transient, being evident that in annual pastures the transitory seed banks have a main role in the regeneration of the species.

1. During the last century, many plant species typical of heathland and nutrient-poor acidic grasslands have become rare whereas others have remained common. Habitat restoration often fails to enhance the rare species, which may in part be caused by the failure to restore the biogeochemical conditions suited to these species. Many soil variables have been shown to affect plant fitness but it is unknown what their relative importance is and whether any biogeochemical variable acts as a key factor constraining the persistence of rare heathland species.2. We compiled a data set consisting of 300 vegetation samples and the associated soil chemical properties from a range of studies carried out across the Netherlands. We asked whether growth sites of rare and common species typical of heathland and acidic grasslands differed in their biogeochemical properties, and whether growth sites of rare species displayed less variation in soil biogeochemical variables (e.g. had narrower ecological amplitude).3. Regardless of rarity, the species' growth sites were most accurately described by a curvilinear relationship between pH and Al/Ca ratios. Other soil characteristics did not vary systematically with changing acidity of the soil or the patterns were less pronounced. Acidification will therefore most rapidly and predictably result in an increase in Al/Ca ratio whereas this is not necessarily the case for the other soil variables affecting plant fitness.4. The soil ammonium (NH4) concentration and ammonium/nitrate (NH4/NO3) ratio were 3.5 and 3 times higher, respectively, in growth sites of common species compared with those of rare species. No other measured variable differed significantly between rare and common plant species.5. On average rare species had a significantly narrower ecological amplitude than common species for soil biogeochemical parameters.6. Synthesis and applications. A greater sensitivity to high NH4 concentrations in combination with a narrower ecological tolerance zone for a range of soil biogeochemical factors may explain the demise of rare species adapted to nutrient-poor acidic habitats in recent decades. Conservation management should aim to restore low NH4 concentrations and NH4/NO3 ratios. Experimental studies indicate that the most effective way to do this is through removal of the topsoil in combination with liming.

Despite recent modelling approaches integrating the effects of niche-based processes and dispersal-based processes on local plant species composition, their relative importance is still not clear. We test whether the predictability of local species composition from environmental conditions is influenced by dispersal traits. We analyzed a large database with co-occurrence data, using ordination techniques (DCA and CCA) to identify the major environmental determinants of species composition. The percentage of explained variance in occurrence was quantified for individual species with CCA. Effects of life-history traits on the predictability of occurrence patterns were tested by means of regression analysis, using a generalized linear models approach. The results reveal close correlations between species composition and environmental conditions, implying that the predictability of the set of species that might occur in a given environmental setting ("habitat species pool") is high. The habitat species pool, however, reflects the potential species composition, and not the actual local situation. At the level of individual species, a large proportion (>90%) of the variation in occurrence remained unexplained. Predictability of species occurrence patterns was increased by a greater capacity for long-distance dispersal, greater adult longevity and the capacity to build a persistent seed bank. The results indicate that the predictability of species composition from environmental conditions is reduced by a few orders of magnitude by dispersal limitation and that poor dispersers are underrepresented.

Seed longevity of plant species is an important topic in restoration management, and little is known about the effects of environmental conditions on seed survival and longevity under natural conditions. Therefore, the effect of groundwater level on the survival of seeds in the soil seed bank of a natural grassland community was investigated. Large soil cores, mesocosms, were sampled from a grassland site and transferred to two basins under a glass roof. The mesocosms were subjected to different groundwater-level treatments (high and low, respectively 5 and 30 cm below the soil surface) for nearly three years. After that period the soil seed bank of the mesocosms was sampled. In total 15 789 seeds of 38 taxa emerged from the experiment. Significant differences between the number of viable seeds that emerged in the two treatments were found for several species. More seeds ofGlyceria fluitans, Cardamine pratensisandMyosotis palustrisgerminated in the high water-level treatment, whereas fewer seeds ofJuncusspp.,Cerastium fontanumandStellaria mediawere found in this treatment than in the low water-level treatment. The experiment showed that the anoxic conditions prevailing in the high water-level treatment were beneficial to the survival of seeds of species of wet grassland communities. Species of dry grasslands, although represented by only two species, survived better under aerobic conditions.

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

Summary 1. Soil seed banks of 38 grassland sites in western Europe were sampled and species composition was determined. All sites differed in geographical region, soil type and intensity of management. 2. Relationships between the composition of the seed bank, the established vegetation, and soil and management parameters were analysed using different ordination techniques. 3. Common species in the seed bank of extensively managed grasslands were Juncus without septa, Plantago lanceolata, Holcus lanatus and Cerastiumfontanum. General differences in the species composition reflected the country of origin of the sites. 4. Differences between sites within a chronosequence were used to interpret the impact of management on the proportion of species in the seed bank representing different functional groups. Seed banks were generally dominated by species of mid-range nutrient conditions. Species associated with poor nutrient conditions were relatively scarce at most sites. 5. Intensive agricultural management had a negative effect on the soil seed bank of grassland species, whereas lack of management or abandonment resulted in the loss of grassland species from both the vegetation and the soil seed bank owing to the invasion of woodland species. Restoration management, following long periods of intensive use, took more than 20 years to establish a significant increase in species of poor nutrient conditions. 6. A regeneration index was calculated for each chronosequence to estimate the relative 'distance' between a degraded site and a species-rich target site in the same series. These regeneration indices provide an indication of the timescales required for the restoration of sites towards the species-rich target grassland community types. However, for most agriculturally improved grassland sites, the study indicated that restoration of unimproved or semi-natural types of grassland cannot depend on a high level of recruitment from the seed bank of species which have disappeared from the established vegetation. This implies that maintenance of existing species-rich grassland resources should be given high priority. 7. The results of this seed bank study show that grassland sites with a short history of agricultural improvement or biodiversity degradation are likely to be the most worthwhile for restoration purposes.

The soil seed banks of north west Europe , The soil seed banks of north west Europe , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

1. The seedling emergence method for assessing the size of the seed bank is improved by washing soil samples on a fine sieve and spreading the thus concentrated samples in a 3-5 mm thick layer on sterilized potting compost. 2. The method largely increases the number of seedlings that emerge as compared to unconcentrated samples. Hand-sorting afterwards shows that the germination rates vary between 81 and 100% of the viable seeds present. 3. Ninety-five per cent of the seedlings will emerge within 6 weeks using this method. 4. The method greatly reduces the greenhouse space needed and enables examination of large sample volumes.