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Für die Inventurpunkte der zweiten Bundeswaldinventur (BWI2) im Land Brandenburg liegen umfangreiche Bodenund Standortsinformationen vor, die zum einen direkt aus der Bodenzustandserhebung (BZE) stammen und zum anderen mit Hilfe eines ausgewählten Regionalisierungsansatzes generiert wurden. Es erfolgt eine Verknüpfung der Bestandes- und Bodendaten und eine stichprobenbezogene Modellierung der Standorts-Leistungs-Beziehung für die Baumart Kiefer unter Berücksichtigung des Bestandesalters. Die in unterschiedlichen Teilkollektiven ermittelten Regressionsmodelle liefern bei einem R2-Wert von 0,56 identische Einflussgrößen (Nährkraft, Verdunstung) und vergleichbare Parameterkoeffizienten für die Zielgröße der absoluten Höhenbonität. Im Hinblick auf die Bonitäts-Alters-Beziehung ergibt sich aufgrund allgemein verbesserter Standortsbedingungen ein Vorteil der Jungbestände gegenüber den Altbeständen. Dieser Effekt ist umso stärker, je geringer die Stammnährkraft an einem Standort ist.
Im Rahmen eines Waldklimafonds-Projektes werden auf
Basis von Daten der Bodenzustandserfassung im Wald (BZE) und zusätzlichen Bodenprofilen Bodendaten auf die Traktecken der Bundeswaldinventur (BWI) so übertragen, dass nicht nur die Schätzdaten für die Parametrisierung klimasensitiver Wachstumsmodelle verfügbar, sondern auch deren Fehler abgeschätzt werden. Auf der Basis einer unabhängigen Validierung werden klassische Regressionstechniken (OLS, Regression-Kriging) alternativ zu Random-Forestsund BRT-Modellen getestet. Die Beobachtungsdatenbasis für die Modellbildung stammt aus den Messungen und Bodenbeschreibungen der BZE, anderen Projektdaten und der Forstlichen Standortskartierung. Die Regiogalisierung von 13 Zielgrößen (Skelettgehalt, Trockenrohdichte, %Sand, %Schluff, %Ton, Gründigkeit, nFK, Hydromorphie, C-Gehalt, C/N-Verhältnis, Basensättigung, effektive Kationen Austauschkapazität, pHKCl) wird in 1–2 Bodentiefen durchgeführt, was je 25 Regionalisierungsmodelle in 8 aggregierten Bodengroßlandschaften der BÜK1000 ergibt. Für die Modellanwendung werden individuell für die Charakteristika dieser Straten angepasste Prädiktorensets identifiziert und so die Erklärungsgüte der Modelle maximiert. Dieser Beitrag gibt einen Überblick über die bundesweite Auswertungsstruktur, beschränkt sich für methodische Details und Ergebnisse aber hauptsächlich auf die Region Alpenvorland und Nördliche Kalkalpen. Dabei wird gezeigt: 1. dass eine objektive Abgrenzung von Regionalisierungsregionen anhand der naturräumlichen Variabilität der Zielvariablen innerhalb und zwischen Regionen 2. sowie eine länderübergreifende Regionalisierung trotz unterschiedlicher Datenqualitäten in den Ländern mit vertretbarem Fehlerrahmen möglich ist, 3. und die Auswirkung unterschiedlicher Datenqualitäten auf das Regionalisierungsergebnis quantifiziert werden kann. Bisherige Regionalisierungen von Bodendaten haben gezeigt, dass der Anteil der erklärten Parametervarianz zwischen ca. 50 und 80 % zu erwarten ist, dass die Residuen zufällig verteilt und nicht räumlich autokorreliert sind.
Over the last few decades, considerable attention has focused on small-scale studies of invasive plants and invaded systems. Unfortunately, small scale studies rarely provide comprehensive insight into the complexities of biological invasions at macroscales. Systematic and repeated monitoring of biological invasions at broad scales are rare. In this report, we highlight a unique invasive plant database from the national Forest Inventory and Analysis (FIA) program of the United States Forest Service. We demonstrate the importance and capability of this subcontinental-wide database by showcasing several critical macroscale invasion patterns that have emerged from its initial analysis: (1) large portion of the forests systems (39%) in the United States are impacted by invasive plants, (2) forests in the eastern United States harbor more invasive species than the western regions, (3) human land-use legacies at regional to national scalesb may drive large-scale invasion patterns. This accumulated dataset, which continues to grow in temporal richness with repeated measurements, will allow the understanding of invasion patterns and processes at multi-spatial and temporal scales. Such insights are not possible from smaller-scale studies, illustrating the benefit that can be gained by investing in the development of regional to continental-wide invasion monitoring programs elsewhere.
New Zealand harbours a considerable number of alien plants and animals, and is often used as a model region for studies on factors determining the outcome of introductions. Alien birds have been a particular focus of research attention, especially to understand the effect of propagule pressure, as records exist for the numbers of birds introduced to New Zealand. However, studies have relied on compilations of bird numbers, rather than on primary data. Here, we present a case study of the alien yellowhammer (Emberiza citrinella) introduced from the UK to New Zealand, to demonstrate how recourse to the primary literature highlights significant data gaps and misinterpretations in these compilations. We show that the history of the introduction, establishment and spread of the yellowhammer in New Zealand can be reconstructed with surprising precision, including details of the ships importing yellowhammers, their survival rates on board, the numbers and locations of release, and the development of public perception of the species. We demonstrate that not all birds imported were released, as some died or were re-transported to Australia, and that some birds thought to be introductions were in fact translocations of individuals captured in one region of New Zealand for liberation in another. Our study confirms the potential of precise historical reconstructions that, if done for all species, would address criticisms of historical data in the evidence base for the effect of propagule pressure on establishment success for alien populations.
Non-native rats (Rattus spp.) threaten native island species worldwide. Efforts to eradicate them from islands have increased in frequency and become more ambitious in recent years. However, the long-term success of some eradication efforts has been compromised by the ability of rats, particularly Norway rats (Rattus norvegicus) which are good swimmers, to recolonize islands following eradications. In the Falkland Islands, an archipelago in the South Atlantic Ocean, the distance of 250 m between islands (once suggested as the minimum separation distance for an effective barrier to recolonization) has shown to be insufficient. Norway rats are present on about half of the 503 islands in the Falklands. Bird diversity is lower on islands with rats and two vulnerable passerine species, Troglodytes cobbi (the only endemic Falkland Islands passerine) and Cinclodes antarcticus, have greatly reduced abundances and/or are absent on islands with rats. We used logistic regression models to investigate the potential factors that may determine the presence of Norway rats on 158 islands in the Falkland Islands. Our models included island area, distance to the nearest rat-infested island, island location, and the history of island use by humans as driving variables. Models best supported by data included only distance to the nearest potential source of rats and island area, but the relative magnitude of the effect of distance and area on the presence of rats varied depending on whether islands were in the eastern or western sector of the archipelago. The human use of an island was not a significant parameter in any models. A very large fraction (72%) of islands within 500 m of the nearest potential rat source had rats, but 97% of islands farther than 1,000 m away from potential rat sources were free of rats.
Using the MAXENT algorithm, we developed risk maps for eight invasive plant species in southern Transylvania, Romania, a region undergoing drastic land-use changes. Our findings show that invasion risk increased with landscape heterogeneity. Roads and agricultural areas were most prone to invasion, whereas forests were least at risk.
Lantana camara L., considered among the world’s worst invaders is in identity crisis and contentiously referred as Lantana camara L. (sensu lato). Taxonomic ambiguity in L. camara L. (sensu lato), a species complex is one of the grim caveats behind incompetence of its management efforts. Recognizing the extent of variability within the complex, we aim to highlight the need to circumscribe its composition to bring effective management and control efforts into practice. There is a need for clear terminology to examine weedy, naturalized and/or invasive complex constituents that have been placed under the contentious umbrella of 'L. camara L. (sensu lato)'. The time is ripe for invasion ecologists, cytogeneticists and conservationists to collaboratively focus on disentangling the complex and integrate their knowledge and expertise into management and control programs.
Recent critics of invasion biology advocate reduced efforts against nonnative species, arguing that attempts to manage invasions are often costly and futile and that managers are indiscriminately managing species regardless of their impact. Whether this criticism has affected ground-level operations is unknown. A survey of land stewards of a major conservation NGO reveals that this plea has not been heeded; in fact, managers report that they would increase nonnative species management if more resources were available. While respondents overwhelmingly listed nonnative, invasive species as their highest priority for management, we found little evidence supporting the criticism that practitioners focus on nonnative species with minimal ecological impact. Additionally, we found that more conservation practitioners reported managing problematic "weedy" native species over nonnative species that are not invasive. Our results indicate that these managers are selective rather than profligate, targeting species that are having a demonstrable impact or are likely to do so. They feel hamstrung by resource shortages despite their rigorous target selection. Why the increasing literature calling for changed treatment of nonnatives has not led to changed operations is uncertain. Possible reasons are that the critics are not prescriptive or unified about management prioritization, or that these managers simply reject the proposed new paradigm.
The impacts of invasive alien species are greatest when they become dominant members of a community, introduce novel traits, and displace native species. Invasions by alien mollusks represent a novel context by which to compare trait differences between generalist native and introduced herbivores in terrestrial ecosystems. Here, we determined the abundance, habitat, feeding preferences, as well as the metabolic rate of the native Pacific banana slug (Ariolimax columbianus) and the alien black slug (Arion rufus) in the coastal forests of British Columbia, Canada. Through a series of observational and experimental studies, we found that alien slugs are more abundant, differ in their habitat preferences, and consumed more fungi (mushrooms) than native banana slugs. Conversely, in an enclosures experiment we found that herbivory damage by native slugs was higher compared to enclosures with alien only and control enclosures. Finally, metabolic rates were similar for both slug species. These results suggest that alien black slugs possess a suite of traits that make them functionally different from native banana slugs.
Numerous fast growing and highly competitive exotic crops are being selected for production of renewable bioenergy. Tolerance of poor growing conditions with minimal inputs are ideal characteristics for bioenergy feedstocks, but have attracted concern for their potential to become invasive. Miscanthus × giganteus is one of the most promising bioenergy crops in the US, but grower adoption is hindered by high establishment costs due to sterility. Newly developed fertile tetraploid M. × giganteus may streamline cultivation while reducing establishment costs. However, fertile seed dramatically increases the potential propagule pressure, and thus probability of off-site plant establishment. To empirically evaluate the invasive potential of fertile M. × giganteus in the Southeastern US, we compared fitness and spread potential relative to ten grass species comprising 19 accessions under both high and low levels of competition and disturbance. We chose species known to be invasive in the US (positive controls: Arundo donax, naturalized M. sinensis, M. sacchariflorus, Phalaris arundinacea, Sorghum halepense) and non-invasive (negative controls; Andropogon gerardii, ornamental M. sinensis, Panicum virgatum, Sorghum bicolor, Saccharum spp.). This novel design allows us to make relative comparisons of risk among species with varying invasiveness. After three years of establishment and growth in Blacksburg, Virginia, neither aboveground disturbance nor interspecific weed competition influenced fitness for fertile M. × giganteus or our positive and negative control groups. Fertile M. × giganteus produced 346% and 283% greater aboveground biomass than our positive and negative species, respectively. However, fertile M. × giganteus produced 74% fewer inflorescences m-2 than our positive controls and 7% and 51% fewer spikelets inflorescence-1 than the positive and negative control species. After 18 months of growth, we observed the vegetative and seedling spread of three of our positive control species (S. halepense, P. arundinacea, and M. sacchariflorus) outside the cultivated plot into receiving areas of both high and low competition. After 24 months of growth, numerous species were observed outside the cultivated plot including fertile M. × giganteus and 50% of negative control species. Notably, in three years sterile M. × giganteus ‘Illinois’ and Arundo donax never moved from the cultivated plot. The addition of fertile seed appears to increase the potential for offsite movement, but within the geographic confines of our empirical evaluation, fertile M. × giganteus seedlings are more similar to native P. virgatum and were not nearly as fast growing or as competitive as our positive control S. halepense. The use of numerous species providing relative comparisons allow us to draw important conclusions which may help prepare for widespread commercialization, while providing novel methodology for ecological risk assessment of new species.
Identifying factors that underlie invasive species colonisation and change in density could provide valuable insights into the mechanisms of biological invasions and for invasive species management. We examined a suite of factors potentially influencing the landscape-level invasion of Lantana camara L., one of the most ubiquitous invasive species in South Asia. These factors included disturbance factors like forest fires, historical habitat modification, and edge effects, in addition to factors like propagule pressure and habitat suitability. We examined the relative importance of these factors on the colonisation and change in density of L. camara in the Biligiri Rangaswamy Temple Tiger Reserve, Western Ghats, India. We used extensive (1997–2008) datasets tracking the presence and abundance of L. camara and combined these with corresponding data on disturbances, propagule pressure, and habitat suitability. We used an information-theoretic model selection approach to determine the relative importance of each factor on the colonisation and change in density of L. camara. Colonisation was mainly a function of proximity to already established populations (i.e. propagule pressure), whereas increase in L. camara density appeared to be constrained by high fire frequency. Research and management efforts need to recognize the multidimensional nature of mechanisms underlying L. camara’s success during different invasion phases when strategizing interventions to mitigate its effects.
Mutualisms are important structuring forces in ecological communities, influencing ecosystem functions, diversity, and evolutionary trajectories. New interactions, particularly between native and non-native species, are globally increasing in biotic communities as species introductions accelerate. Positive interactions such as novel mutualisms can affect the fitness of organisms in invaded communities. Non-natives can augment native mutualism networks, replace extinct native partners, or disrupt native mutualisms. Because they are actively forming or newly formed, novel mutualisms offer a unique opportunity to examine in real time the factors governing early mutualism formation and stability, including frequency-dependent processes and those relying on specific traits or functions. These central ecological questions have been inferred from long-formed mutualisms, but novel mutualisms may allow a glimpse of successes and failures in ecological time with insights into the relative importance of these factors as ecological systems shift. To this end, this commentary addresses how novel mutualisms inform our understanding of mutualism formation, stability, the importance of functional traits, and niche vs. neutral processes, using examples across multiple systems. Novel mutualism research thus far has been largely limited in both questions and ecosystems, but if more broadly applied could benefit both theoretical and applied ecology.
The trade in plants for planting is a major pathway for the introduction and further spread of alien plants, pests and diseases. Information about the structure of plant trade networks is not generally available, but it is valuable for better assessing the potential risks associated with the trade in live plants and the development of prevention and mitigation measures and policy. The discovery of two larvae of Anoplophora chinensis (citrus longhorn beetle – CLB) in 2009, at a nursery importing Acer palmatum from China in one of the major Dutch tree nursery areas, has resulted in the creation of a detailed dataset on the intra- European Union trade in its potential hosts. This study describes European imports of the primary host of A. chinensis, Acer spp., into the Netherlands (1998-2012) and the effects of the finding in a tree nursery area. In addition, shipments of Acer spp. from 138 producers in the nursery area in 2009 were analysed in a one-off analysis of intra-EU trade. The volume of Acer spp. imports from Asia was stable early during the studied period, and declined to 5% of the initial imports after a period of interceptions, illustrating the effect of regulations. The number of notifications of A. chinensis infestations in imported consignments of Acer spp. increased sharply in the years up to 2007, then declined as imports also reduced. Although plants were shipped to destinations throughout Europe, each producer shipped plants only to few destinations in few countries. Most of the plants were shipped to nurseries in EU countries. These patterns could make it easier to target these high risk destinations for control measures. The lack of transaction records makes it difficult to trace the destination of plants. More systematic electronic record keeping by traders and growers and the data being collated in a database that can be made available to regulatory authorities, together with further studies of plant trade data using network approaches, would be beneficial for improving trace-back and trace-forward and provide better safeguards for plant health and quality.
UV-B radiation represents a potentially selective, yet little studied environmental factor for plant invasions, especially with respect to germination characteristics and seedling establishment in areas of high UV-B exposure such as New Zealand. To explain invasive potential of plant species pre-adaptation and local adaptation to selection factors in the invaded range are two frequently consulted concepts. To test for the relevance of these mechanisms, it is necessary to compare both invasive and non-invasive species, as well as native and exotic origins of invasive species. In the present study, germination success of two congeneric species pairs of the genera Verbascum (Scrophulariaceae) and Echium (Boraginaceae) were investigated under high UV-B intensities. Each genus comprised one species that has successfully invaded New Zealand grasslands and one species that was introduced but has not been invasive in New Zealand. In an among-species approach, pre-adaptation was tested by comparing germination success of native (European) origins of all four species in relation to their different invasive success in New Zealand. In a within-species comparison, native (European) and exotic (New Zealand) origins of the two invasive species were compared to test for local adaptation to UV-B in the invaded range. In both approaches, UV-B radiation inhibited the germination success of all study species. However, the comparison of invasive and non-invasive species of the two genera showed no UV-B-specific pre-adaptation of invasive species to high UV-B intensities. Higher germination success of invasive species probably led to an establishment advantage during colonization of the invaded range. Although local adaptation of exotic populations to UV-B could not be demonstrated in the within-species approach, a genetic shift in germination velocity between native and exotic origins was found. These differences may be ascribed to other relevant environmental factors, e.g. overall irradiation and drought, inducing similar plant responses as under UV-B radiation.
The species of Aequorea attract much scientific interest as they contain the unique Green Fluorescent Protein (GFP). In this work we describe for the first time the discovery of a hydrozoan jellyfish belonging to the genus Aequorea from the Israeli eastern Mediterranean that contains and exhibits fluorescent protein. Finding Aequorea macrodactyla (Brandt, 1835) in the eastern Mediterranean indicates that changes are occurring in the gelatinous fauna of this area. This hydromedusa is known in the seas adjoining the Mediterranean though most of its records are more than four decades old. We examined and identified the newly discovered Israeli Aequorea species by combining two phylogenetic systems, traditional morphological phylogeny and molecular phylogenetics. The molecular identification determined that the species is A. macrodactyla but with minor genetic differences in the mtDNA 16S gene marker. A 1% difference between the Israeli and the Japanese A. macrodactyla was demonstrated, which suggests that the genetic difference between the Israeli and the Japanese population is small but existent. Invasive pathways for this jellyfish were examined by phylogenetic and taxonomic relationships with similar Cnidaria. The results indicate introduction from the Indo-Pacific as invasive pathway, probably by human transportation, and the discovery of A. macrodactyla in the eastern Mediterranean Sea could be interpreted as part of the changes in marine biota as a result of cumulative effects of anthropogenic and global changes that affect the eastern Mediterranean basin.
Status and restoration potential of heathlands and sand grasslands in the southwest of Luxembourg
(2017)
In Europe, semi-natural nutrient-poor ecosystems such as sand grasslands and heathlands have shown extreme declines in surface area and species richness within the last century. The remaining sites are hence of high conservation value. This study analysed the vascular plant species inventory of established and recently restored heathlands and sand grasslands in the southwest of Luxembourg. Analyses to explain differences in vegetation composition between “old” (remnant sites or sites restored a long time ago) and “new” (recently restored) sites in relation to environmental variables were carried out with DCAs and ANOVA/Mann-Whitney-U tests, respectively. The vegetation of old heathlands had few character species of typical heathland communities (Calluno-Ulicetea, Nardetalia), whereas new heathland sites were preponderantly marked by taxa of meso- or eutrophic grasslands and ruderal communities. New heathland sites mainly differed from old sites by higher soil phosphorus contents. Sand grassland vegetation was species-rich and composed by species of the Sedo-Scleranthetea and Festuco-Brometea. With increasing age of the sites, vegetation composition shifted to grass dominance with species of the Molinio-Arrhenateretea. New sand grasslands differed from old sand grasslands by higher soil pH, higher soil potassium content and lower graminoid cover. The differences between new and old sites of both habitat types could mainly be explained by successional processes or were a result of topsoil removal. In some cases, former anthropogenic impact at or in close proximity of restored sites resulted in unsuitable conditions, such as alkaline soil on former landfill sites or highly eutrophic soil due to intensive agriculture. Future management options for the study sites are discussed.
This study describes the vascular flora and community structure of grasslands occurring on heaps of waste rock left by former Zn-Pb mining in relation to the metal content in the soil and other environmental factors. The study was performed on 65 heaps scattered in agricultural land in southern Poland. The sites were described in terms of plant community characteristics, soil physicochemical properties, distance from woodland, altitude and local climate. The number of plant species and proportion of species of the Festuco-Brometea class decreased with increasing heavy metal (Cd, Pb, Zn) content in the soil, and increased with Ca content and pH of the soil. There was a negative relationship between the proportion of the later successional species and heavy metal content in the soil and a positive relationship between plants connected with the earlier stages of succession and metals. Floristic composition was also affected by distance from woodland and height above sea level. The investigated heaps were primarily colonised by native species dispersed by wind, characterised as competitive stresstolerant, ruderal and competitive strategy species. Three types of Carlino acaulis-Brometum erecti (CB) communities were distinguished: CB typicum – dominated by Brachypodium pinnatum, with the highest proportion of calcareous grassland species, CB festucetosum ovinae subass. nova – loose grassland with abundant facultative metallophytes, and the CB rubietosum caesi subass. nova with nutrientdemanding ruderal and woody plants invading from the nearby forest communities. The three subassociations represent different successional stages of Carlino acaulis-Brometum erecti, strongly dependent on both the substrate and spatial relations. The proportions of species traits, especially a high occurrence of endangered species and a very low proportion of alien species show that the post-mining habitats studied have a similar degree of ‘naturalness’ as valuable xerothermic grasslands on nonmetalliferous habitats. They thus may be considered as valuable objects for the protection of plant diversity.
This paper provides a comprehensive survey of the results of phytocoenological research into Alnus incana forests from the alliance Alnion incanae in the Dinarides. Stands from the south-eastern Dinarides (Alnetum incanae = Oxali-Alnetum incanae) were analyzed and compared with those from the north-western Dinarides (Lamio orvalae-Alnetum incanae). The comparison reveals significant differences in the floristic composition and in the degree of differentiation – and particularly in the presence of the species of the Illyrian floristic geoelement. Focus was placed on the area of western Croatia where a geographic variant of Helleborus dumetorum had previously been defined within the association Lamio orvalae-Alnetum incanae. Two of its subtypes, Salix alba and Alnus glutinosa, were determined in our research. The former subtype thrives on occasionally flooded, moist sites, where the floristic composition is dominated by hygrophytes. The latter subtype grows on elevated and drier terraces and is richer in mesophilous species from the surrounding zonal forests. A floristic-sociological comparison of the Lamio orvalae-Alnetum incanae with the related syntaxa indicates the presence of about fourty diagnostic species which accentuate its independence and the need to assess it at the level of an independent, regional association within the alliance Alnion incanae.
The aim of our study was to reveal the differences in the species composition and soil properties of open sandy grasslands dominated by different Festuca species, Festuca vaginata and F. pseudovaginata. Due to the arid conditions, sandy grasslands are generally covered by xerothermic vegetation in which F. vaginata is a typical dominant species. Festuca pseudovaginata, a species newly described by the authors, can also gain dominance in sandy grasslands. However, species composition and soil properties of grasslands dominated by this recently discovered species are still undiscovered. Based on previous coenological studies, we hypothesised that the grasslands characterised by the endemic F. vaginata are more species-rich than those with F.pseudovaginata.
Coenological sampling was carried out in May 2009 at two study sites using the Braun-Blanquet method in quadrats of 2 m × 2 m. Five relevés were sampled in stands dominated by F. vaginata and F. pseudovaginata respectively at two study sites in Central Hungary, resulting in a total of twenty relevés. Analyses were based on the cover scores of vascular plant species and cryptogam crust and values of seven soil properties (pH [KCl], pH [H2O], humus, total N, Ca, P2O5 and K2O) measured in the 0–15 and 15–30 cm soil layers. Soil properties of the grasslands dominated by F. pseudovaginata and F. vaginata (dependent variables) were compared by linear mixed models, where ‘grassland type’ was the fixed factor and ‘site nested in grassland type’ was considered as random factor. Data were analysed by cluster analysis, fusion algorithm was a combinatorial method (minimising increase of variance), and the correlation was used as comparative function. We compared the cover of subordinate species by Mann-Whitney U test. We found that F. pseudovaginata and F. vaginata samples were well separated, and grasslands dominated by F. pseudovaginata had nearly two times more species than those dominated by F. vaginata. Based on the cluster analyses using plant cover and upper 0–15 cm soil layer data, F. pseudovaginata and F. vaginata groups could be well separated. Linear mixed models revealed that F. vaginata grasslands were typical on soils with higher pH, nitrogen, phosphorous and potassium contents compared to F. pseudovaginata grasslands, which indicates a tight connection between the properties of the upper soil layer and the vegetation in sandy grasslands.
Bromus racemosus L. is a rather rare grass species of moist meadows. It has strongly decreased in the course of the 20th century due to intensification of agricultural grassland management, and is therefore included in Red Lists of several European countries. Its winter annual life-cycle is remarkable for a species of permanent grasslands.
The aim of this study is to determine the habitat preference and optimal management of B. racemosus in the Netherlands and surrounding countries. Vegetation, soil and hydrological data from 28 sites in the Netherlands have been compared with B. racemosus cover, and with vegetation data from surrounding countries. The results indicate that B. racemosus is characteristic of Molinio-Arrhenatheretea meadows with good mineralisation and aftermath grazing. The optimum lies in grasslands of the alliance Alopecurion pratensis (Deschampsion cespitosae), but the species ranges from wetter Calthion palustris meadows to drier Arrhenatherion elatioris and Cynosurion cristati grasslands. It prefers intermediate nutrient levels and hydrological conditions (mesic sites), but within this range the highest cover is found in relatively nutrient rich and dry sites. Because of the absence of a seedbank and a low dispersal capability, B. racemosus is vulnerable to changes in grassland management. A management of mowing after 15 June and aftermath grazing is most suitable, since it enables fruit ripening and the maintenance of an open sward, needed for germination and development. The risk of extinction is likely to be higher in flat polders than in floodplain sites with natural relief, where the species may shift between belts in different years.