64 research outputs found
Species richness of Orthoptera declines with elevation while elevational range of individual species peaks at mid elevation
Species richness has been shown to decrease, and elevational range increase (the Rapoport effect), with elevation as a consequence of biotic and abiotic factors, but patterns are inconsistent across taxonomic groups. Despite being an important indicator taxon and a component of local communities, Orthoptera distributions at higher elevations in Europe remain unclear. We investigated the relationship of Orthoptera species richness and elevational range with elevation in the Pyrenees mountains, Europe. We conducted sweepnetting surveys supplemented by hand-sampling, at 28 sites stratified by elevation, across three study areas. Using generalised linear models, we found that species richness declined with elevation. Elevation was an important predictor of species richness, but sampling effort and vegetation structure (height and cover) also contributed to estimates of species richness. Using a nonlinear regression to model the elevational range of species over the elevational gradient, we did not observe a Rapoport effect, with elevational range peaking at mid-elevation instead. Smaller elevational ranges of species found at high elevations may be due to a combination of sampling over a restricted elevational range and the presence of specialist high-elevation species. We argue that our findings are useful for understanding species distributions with elevation at the interface between local and regional scales. Clarifying the biotic and abiotic predictors of species distribution is important for informing conservation efforts and predicting consequences of climate change
A novel approach to increasing the reliability of accelerator magnets
Abstract — When a very large particle accelerator with about 8000 electromagnets, such as the proposed Next Linear Collider (NLC), has an 85 % overall availability goal, then all these magnets and their power supplies must be highly reliable and/or quickly repairable. An interdisciplinary reliability engineering approach, more commonly applied to aircraft and space vehicles, has been taken to design maximum reliability in the NLC main linac quadrupoles, while maintaining magnetic field performance and reducing cost. A specially assembled team of engineers with a variety of experiences with magnets carried out a Failure Mode and Effects Analysis (FMEA) on a standard SLAC quadrupole magnet system. This process helped them identify which components were less reliable. Then they redesigned the quadrupole to avoid all the potential problems. A prototype magnet will be made and tested to ensure that functionality has not been lost. Index Terms—Magnet, reliability, FMEA. I
The lesser mottled grasshopper, Stenobothrus stigmaticus: lessons from habitat management at its only site in the British Isles
The lesser mottled grasshopper, Stenobothrus stigmaticus, occurs at a single site in the British Isles. This paper describes the history of site protection and management over 30 years including the introduction of conservation grazing management. Successes have been limited, but this has been due largely to issues around recreational access and stakeholder engagement rather than lack of ecological understanding. Despite severe challenges, sufficient experience has been gained to be confident that grazing by sheep can assist in re-establishing the grasshopper over areas of a protected site from which it is now absent or present in only scattered colonies. The grasshopper requires a short, open grassland and pockets of such vegetation occur naturally because of rabbit-grazing and thin, nutrient poor, free-draining soils around rocky outcrops. These small areas have proved to be critical to the species persistence and provide a nucleus from which spread can occur. Grazing management has involved complex negotiations with multiple stakeholders, including landowners, their agents, the landowners’ tenants, and the tenants’ graziers. Public access, cases of dogs worrying grazing livestock, and objections over the introduction of fencing in a once open landscape have made negotiations more difficult. Future success requires that these issues be addressed. Observations on a golf course within the site, with a remnant population of the grasshopper, suggest that winter-cutting of grassland may be a useful supplement to grazing management while such difficulties remain
Impact of enhanced Osmia bicornis (Hymenoptera: Megachilidae) populations on pollination and fruit quality in commercial sweet cherry (Prunus avium L.) orchards
The impact on pollination of supplementing wild pollinators with commercially reared Osmia bicornis in commercial orchards growing the self-fertile sweet cherry variety “Stella” was investigated in each of two years. The quality characteristics used by retailers to determine market value of fruit were compared when insect pollination was by wild pollinators only, or wild pollinators supplemented with O. bicornis released at recommended commercial rates. No effect of treatment on the number of fruit set or subsequent rate of growth was recorded. However, supplemented pollination resulted in earlier fruit set when compared to pollination by wild pollinators alone and offered the potential benefit of a larger proportion of the crop reaching optimum quality within a narrower time range, resulting in more consistent produce. Retailers use five key quality criteria in assessment of market value of cherries (the weight of individual fruit, width at the widest point, fruit colour, sugar content and firmness). Price paid to growers depends both on meeting the criteria and consistency between fruit in these characteristics. In both years, the commercial criteria were met in full in both treatments, but harvested fruit following supplemented pollination were consistently larger and heavier compared to those from the wild pollinator treatment. In the year where supplemented pollination had the greatest impact on the timing of fruit set, fruit size and sugar content were also less variable than when pollination was by wild species only. The implications for the commercial use of O. bicornis in cherry orchards are considered
Inter-observer variation in habitat survey data: investigating the consequences for professional practice
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Observation of Magnetic Resonances in Electron Clouds in a Positron Storage Ring
The first experimental observation of magnetic resonances in electron clouds is reported. The resonance was observed as a modulation in cloud intensity for uncoated as well as TiN-coated aluminum surfaces in the positron storage ring of the PEP-II collider at SLAC. Electron clouds frequently arise in accelerators of positively charged particles, and severely impact the machines performance. The TiN coating was found to be an effective remedy, reducing the cloud intensity by three orders of magnitude
Differences between urban and rural hedges in England revealed by a citizen science project
Background:
Hedges are oth ecologically and culturally important and are a distinctive feature of the British landscape. However the overall length of hedges across Great Britain is decreasing. Current challenges in studying hedges relate to the dominance of research on rural, as opposed to urban, hedges, and their variability and geographical breadth. To help address these challenges and to educate the public on the importance of hedge habitats for wildlife, in 2010 the Open Air Laboratories (OPAL) programme coordinated a hedge-focused citizen science survey.
Results:
Results from 2891 surveys were analysed. Woody plant species differed significantly between urban and rural areas. Beech, Holly, Ivy, Laurel, Privet and Yew were more commonly recorded in urban hedges whereas Blackthorn, Bramble, Dog Rose, Elder and Hawthorn were recorded more often in rural hedges. Urban and rural differences were shown for some groups of invertebrates. Ants, earwigs and shieldbugs were recorded more frequently in urban hedges whereas blowflies, caterpillars, harvestmen, other beetles, spiders and weevils were recorded more frequently in rural hedges. Spiders were the most frequently recorded invertebrate across all surveys. The presence of hard surfaces adjacent to the hedge was influential on hedge structure, number and diversity of plant species, amount of food available for wildlife and invertebrate number and diversity. In urban hedges with one adjacent hard surface, the food available for wildlife was significantly reduced and in rural hedges, one adjacent hard surface affected the diversity of invertebrates.
Conclusions:
This research highlights that urban hedges may be important habitats for wildlife and that hard surfaces may have an impact on both the number and diversity of plant species and the number and diversity of invertebrates. This study demonstrates that citizen science programmes that focus on hedge surveillance can work and have the added benefit of educating the public on the importance of hedgerow habitats
Scenario-led habitat modelling of land use change impacts on key species
© 2015 Gearyet al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Accurate predictions of the impacts of future land use change on species of conservation concern can help to inform policy-makers and improve conservation measures. If predictions are spatially explicit, predicted consequences of likely land use changes could be accessible to land managers at a scale relevant to their working landscape. We introduce a method, based on open source software, which integrates habitat suitability modelling with scenario-building, and illustrate its use by investigating the effects of alternative land use change scenarios on landscape suitability for black grouse Tetrao tetrix. Expert opinion was used to construct five near-future (twenty years) scenarios for the 800 km 2 study site in upland Scotland. For each scenario, the cover of different land use types was altered by 5-30% from 20 random starting locations and changes in habitat suitability assessed by projecting a MaxEnt suitability model onto each simulated landscape. A scenario converting grazed land to moorland and open forestry was the most beneficial for black grouse, and 'increased grazing' (the opposite conversion) the most detrimental. Positioning of new landscape blocks was shown to be important in some situations. Increasing the area of opencanopy forestry caused a proportional decrease in suitability, but suitability gains for the 'reduced grazing' scenario were nonlinear. 'Scenario-led' landscape simulation models can be applied in assessments of the impacts of land use change both on individual species and also on diversity and community measures, or ecosystem services. A next step would be to include landscape configuration more explicitly in the simulation models, both to make them more realistic, and to examine the effects of habitat placement more thoroughly. In this example, the recommended policy would be incentives on grazing reduction to benefit black grouse
Effects of patch characteristics and within patch heterogeneity on the accuracy of urban land cover estimates from visual interpretation
Resource heterogeneity and community structure: A case study in Heliconia imbricata Phytotelmata
Complex or non-additive differences in the distribution and abundance of arthropod species inhabiting the water-filled bracts of Heliconia imbricata can be created by simple manipulations of resource levels. The primary resources for these assemblages are the corollas of the flowers that accumulate in the bracts. Removing or adding corollas to individual bracts changes the pattern in the abundance of arthropod species within each bract such that bracts with different treatments ultimately differ in composition and numerical associations among species. These results suggest that direct and indirect resource-mediated factors can structure or significantly affect the distribution and abundance of species in these and perhaps other assemblages. Thus, in natural communities, if resources are heterogeneous among patches (such as among the bracts in this study) structure in a given patch may be a function of the resource level of that patch and can differ significantly from neighboring patches that provide different resource levels.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47788/1/442_2004_Article_BF00665591.pd
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