Plant colonization of ex-arable fields from adjacent species-rich grasslands: The importance of dispersal vs. recruitment ability

Species-rich semi-natural grasslands have declined drastically in Europe over the last century and occur in modern landscapes as small and isolated fragments. Recreation of these species-rich plant communities and increasing connectivity of remaining grasslands are important goals for nature conservation. Ex-arable fields located adjacent to species-rich grasslands have been suggested as targets for such recreation, but we still lack knowledge about the processes determining colonization from grasslands to ex-arable fields. We examined transects from species-rich semi-natural grasslands to ex-arable fields in a nature reserve located in southeast Sweden, and analysed relationships between observed colonization of ex-arable fields and two characteristics of species: dispersal ability and recruitment ability. Colonization of ex-arable fields was not related to dispersal ability, assessed as adhesive potential to animal coat, wind dispersal potential and seed mass (related to seed production), but was positively related to recruitment ability, assessed by sowing experiment. The same relationships appeared when using a performance index from sowing experiments conducted in the UK. We conclude that recruitment ability is a key factor for colonization of ex-arable fields. In our study, around 50% of semi-natural grassland species were able to colonize adjacent ex-arable field margins spontaneously within a time window of less than 50 years. Seed sowing is however needed to increase the speed of the colonization process, because increasing seed density promotes colonization of species with poor recruitment in ex-arable fields. Actions to increase area and connectivity of species-rich grasslands should consider incorporating ex-arable fields.     

Review of drivers and barriers for nuclear power in the UK

There has been resurgence in interest in new nuclear power stations over the last couple of years. The UK Government has taken steps to encourage the private sector to build new stations in the UK, a change in its previous neutral stance toward nuclear power. This paper examines the change in government policy asking what drivers have led to this decision and what barriers were preventing new nuclear power in the past and what barriers are still faced by both government and industry. Three main drivers are discussed: security of energy supply; diminishing energy generation capacity; and climate change. The paper also examines other key factors that play a part in facilitating a shift in government policy, namely economics, public perception and waste management policy. Barriers are identified through examination of public perception, and policy. The changes to the planning system are also discussed. The paper concludes by comparing drivers and barriers for other technologies and contrasting the UK experience with that of other countries.     

Genotypic and phenotypic diversity in populations of plant-probiotic <Emphasis Type="Italic">Pseudomonas</Emphasis> spp. colonizing roots

Several soil microorganisms colonizing roots are known to naturally promote the health of plants by controlling a range of plant pathogens, including bacteria, fungi, and nematodes. The use of theses antagonistic microorganisms, recently named plant-probiotics, to control plant-pathogenic fungi is receiving increasing attention, as they may represent a sustainable alternative to chemical pesticides. Many years of research on plant-probiotic microorganisms (PPM) have indicated that fluorescent pseudomonads producing antimicrobial compounds are largely involved in the suppression of the most widespread soilborne pathogens. Phenotype and genotype analysis of plant-probiotic fluorescent pseudomonads (PFP) have shown considerable genetic variation among these types of strains. Such variability plays an important role in the rhizosphere competence and the biocontrol ability of PFP strains. Understanding the mechanisms by which genotypic and phenotypic diversity occurs in natural populations of PFP could be exploited to choose those agricultural practices which best exploit the indigenous PFP populations, or to isolate new plant-probiotic strains for using them as inoculants. A number of different methods have been used to study diversity within PFP populations. Because different resolutions of the existing microbial diversity can be revealed depending on the approach used, this review first describes the most important methods used for the assessment of fluorescent Pseudomonas diversity. Then, we focus on recent data relating how differences in genotypic and phenotypic diversity within PFP communities can be attributed to geographic location, climate, soil type, soil management regime, and interactions with other soil microorganisms and host plants. It becomes evident that plant-related parameters exert the strongest influence on the genotypic and phenotypic variations in PFP populations.     

Climate change, aerobiology, and public health in the Northeast United States

The epidemiological implications with respect to climate change and public health (e.g., shifts in disease vectors) are beginning to be acknowledged. Less recognized however, are the potential links between climate, plant biology and public health. In addition to being affected by climate (e.g., temperature determines plant range), carbon dioxide (CO₂) represents the raw material needed for photosynthesis and its rapid increase in the atmosphere is expected to stimulate plant growth. While there are a number of means by which plant biology intersects with human health (e.g., plant nutrition), one of the most widely recognized is aerobiology; specifically, the ability of plants to both produce pollen and to serve as a substrate for molds/fungi (e.g., sporulation). The current review represents an initial attempt to coalesce what is known regarding the likely impacts of climate/CO₂ on plant pollen/fungal spores and associated allergic disease that are, or could be, specific to the Northeast United States. Although the current results indicate a number of potentially unfavorable effects, we wish to stress that the current data are based on a small number of experiments. Additional data are crucial to both reduce epidemiological uncertainty and to derive a robust set of mitigation / adaptation strategies.     

Behavioral genomics of honeybee foraging and nest defense

The honeybee has been the most important insect species for study of social behavior. The recently released draft genomic sequence for the bee will accelerate honeybee behavioral genetics. Although we lack sufficient tools to manipulate this genome easily, quantitative trait loci (QTLs) that influence natural variation in behavior have been identified and tested for their effects on correlated behavioral traits. We review what is known about the genetics and physiology of two behavioral traits in honeybees, foraging specialization (pollen versus nectar), and defensive behavior, and present evidence that map-based cloning of genes is more feasible in the bee than in other metazoans. We also present bioinformatic analyses of candidate genes within QTL confidence intervals (CIs). The high recombination rate of the bee made it possible to narrow the search to regions containing only 17–61 predicted peptides for each QTL, although CIs covered large genetic distances. Knowledge of correlated behavioral traits, comparative bioinformatics, and expression assays facilitated evaluation of candidate genes. An overrepresentation of genes involved in ovarian development and insulin-like signaling components within pollen foraging QTL regions suggests that an ancestral reproductive gene network was co-opted during the evolution of foraging specialization. The major QTL influencing defensive/aggressive behavior contains orthologs of genes involved in central nervous system activity and neurogenesis. Candidates at the other two defensive-behavior QTLs include modulators of sensory signaling (Am5HT ₇ serotonin receptor, AmArr4 arrestin, and GABA-B-R1 receptor). These studies are the first step in linking natural variation in honeybee social behavior to the identification of underlying genes.     

Prüfanforderungen des Umweltbundesamtes zur Bewertung der Auswirkungen von Pflanzenschutzmitteln auf terrestrische Pflanzen

The fundamental data requirements for the authorization of plant protection products and the inclusion of active ingredients in Annex I of Council Directive 91/414/EEC are described in the Annexes II and III of this Directive. Definite instructions with regard to preconditions and for implementation and methodology (guidelines) concerning investigations with terrestrial plants are deficient. In the following, the scientific data requirements are explained for assessing the effects of plant protection products on terrestrial plants.     

Eintragspfade von PCDD/PCDF-Belastungen über landwirtschaftliche Rohstoffe und Futtermittel in die menschliche Nahrungskette

Ohne Zusammenfassung     

Identifying the antecedents of coping with an organizational acquisition: a structural assessment

This study used Lazarus and Folkman's ( 1984 ) cognitive–phenomenological model of coping and Lazarus's ( 1991 ) theory of emotions to develop and test a model of how individuals cope with an organizational acquisition. The model identifies the origins and process used to select both problem‐focused and emotion‐focused coping strategies. Covariance structure analysis of data from 172 individuals indicated that problem‐focused coping was directly influenced by primary appraisal and negative emotion, while only certain types of emotion‐focused coping were directly related to negative emotion. All coping strategies were impacted by social support. Furthermore, negative emotion was predicted by primary appraisal, which in turn was related to perceived control, coping efficacy, and environmental conditions. Recommendations for future research and applications are discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

Communication with police supervisors and peers as a buffer of work‐related traumatic stress

Traumatic events are a particular type of stressor that may affect police officers engaged in front line duties. In this study, specific types of social support predicted to buffer the psychological and physical health effects of trauma are drawn from theory and empirical evidence in the area of post‐traumatic stress. Social support, measured as the content of communication, and the ease of talking about trauma was tested with 527 working police officers who responded to a questionnaire survey. Hierarchical regression analysis showed that the communication variables contributed to the variance in post‐traumatic stress disorder and physical symptoms with differential effects for different aspects of communication. Analysis of the effects of traumatic stress on symptoms for sub‐groups at different levels of communication showed that some types of communication, such as the ease of talking about trauma or positive communications about work, moderate the effects of stress for police officers, in that higher levels are associated with a weaker trauma–strain relationship. However, some types of communication buffered stress only at moderate levels and other types may not be protective. These results are discussed in terms of the types and sources of social support that are likely to buffer post‐traumatic stress at work. Copyright © 2000 John Wiley & Sons, Ltd.