404 research outputs found
Network properties data and code used in "Ecological plasticity governs ecosystem services in multilayer networks".
No full textCode and network properties data used in the analyses presented in "Ecological plasticity governs ecosystem services in multilayer networks". Further information can be requested of the author David A. Bohan ([email protected])
Ballooning dispersal in arthropod taxa: conditions at take-off
No full textWe have solved a long-standing and seemingly paradoxical set of questions that relate to the conditions which govern spider ballooning. We show that observations of spider ballooning excursions are best explained by meteorological conditions which maximize dispersal. Dispersal is predicted to be most effective in terms of distance when the stability of the atmosphere is non-ideally convective and is less effective during purely convective or neutrally stable conditions. Ballooners are most likely to travel a few hundred metres, but dispersal distances of several hundred kilometres are possible
Atlanta’s Desegregation Era Social Studies Curriculum: An Examination of Georgia History Textbooks
No full textAuthor accepted manuscript version of a chapter published in:
Bohan, C. H. & Randolph, P. (2012). Desegregation era social studies curriculum: An examination of Georgia History textbooks. Chapter seven in C. Woyshner and C. H. Bohan (Eds.) Histories of social studies and race, 1890–2000. (pp. 135−158). New York: Palgrave MacMillan.</p
Conceptualizing pathways to sustainable agricultural intensification
No full textThere is widespread consensus among scientists, policy makers, and practitioners that agriculture should become more sustainable, while maintaining the ability to meet future food demand. However, there are still many diverging views on what sustainable intensification means, and how to get there. In this article, we present a conceptual framework to navigate agricultural intensification pathways. The conceptual framework aligns three research themes central to improving the sustainability of agriculture: (1) What are the social, economic, and environmental trade-offs of alternative agricultural intensification options? (2) How do land managers decide on intensification strategies, and how can the adoption of sustainable practices be made more attractive? (3) How do socio-political, technological, and environmental mega-trends and other drivers of change affect sustainable intensification measures and agricultural landscapes? The framework presented here goes beyond earlier frameworks by considering multiple dimensions of intensity and sustainability, drawing from both natural and social science theories. Also, it operates across spatial and temporal scales, and is outcome-focused while explicitly considering the linkages between decision making processes and sustainability outcomes. We argue that given these novelties the conceptual framework can serve as a blueprint to assess pathways towards sustainable agricultural intensification
The challenges of linking ecosystem services to biodiversity : lessons from a large-scale freshwater study
No full textWe explore some of the key challenges and opportunities that lie in assessing the role of freshwater biodiversity in sustaining ecosystem services, using the recent large interdisciplinary NERC-DURESS project (www.nerc-DURESS.org) as an exemplar case study of wider issues. The conceptual and methodological challenges raised are identified, explored and a range of methods are proposed to quantify how freshwater ecoservices, such as fish production or water quality regulation, depend on river organisms, and how we might identify biodiversity thresholds under which a service is likely to be compromised. We conclude that interdisciplinary, large scale, in situ approaches like these are needed to (i) fully understand how river biodiversity sustains ecosystem services; (ii) help evaluate if, where, and how the ecosystem approach can benefit long-term resource management and (iii) maximise impacts on policy, practice and decision making, which can be especially effective where strong ‘co-production’ partnerships with a broad range of stakeholders are developed and nurtured from a project's outset
Disentangling the Pathways and Effects of Ecosystem Service Co-Production
No full textResearch on ecosystem services has become a dominant field within environmental management, framing the way in which human–nature relationships are understood and managed. Although ecosystem services are usually defined as ‘the benefits that humans receive from nature’, our work shows that most services are actually co-produced by a mixture of natural capital and various forms of social, human, financial and technological capital. Here, we review how ecosystem services are co-produced, and then we assess how this affects the quantity, quality, trade-offs, resilience and the equity of the distribution of ecosystem services. Then we discuss the implications of co-production for sustainability. Finally, we present some challenges for an adequate consideration of co-production within the assessment of ecosystem services
Prey choice by carabid beetles feeding on an earthworm community analysed using species- and lineage-specific PCR primers
No full textThe carabid beetle Pterostichus melanarius is a major natural enemy of pests, such as aphids and slugs in agricultural systems. Earthworms are a dominant non-pest component of the diet of P. melanarius which help sustain the beetles during periods when the pest population is low or absent. In this study we wanted to test whether this predator exercises prey choice among different earthworm species or ecological groups. High levels of genetic diversity within morphological species of earthworm necessitated the development of primers that were specific not just to species but lineages and sub-lineages within species as well. Gut samples from beetles were analysed using multiplex-PCR and fluorescent-labelled primers. Calibratory feeding trials were undertaken to calculate median detection times for prey DNA following ingestion. Extensive testing demonstrated that the primers were species-specific, that detection periods were negatively related to amplicon size and that meal size had a highly significant effect on detection periods. Monte Carlo simulations showed that, in general, worms were being predated in proportion to their densities in the field with little evidence of prey choice, other than probable avoidance of the larger, deep-living species. There was no evidence that epigeic species were being taken preferentially in comparison with endogeic species. There was also no evidence that defensive secretions by Allolobophora chlorotica reduced predation pressure on this species by P. melanarius. We concluded that any management system that increases earthworm densities generally, regardless of component species, is likely to be optimal for increasing numbers of this beneficial beetle predator
Spatial co-occurrence networks predict the feeding histories of polyphagous arthropod predators at field scales
No full textIn agricultural systems, polyphagous beetles and spiders are abundant components of the beneficial arthropod community. Although data on the dietary ranges of these groups is increasing, remarkably little is understood regarding how individuals interact with their prey at small spatial scales. We demonstrate the utility of a spatially-explicit network model that integrates predator behaviour using predator-prey co-occurrences. Three co-occurrence matrices, one each for June, July and August, were generated using Vortis suction sample data collected from an 80 point grid imposed on a field of winter wheat. Heuristic predator-prey linkages, based on positive spatial co-occurrence, were imposed on these three matrices to create networks. It was found that primary consumers were highly aggregated and showed a strong tendency to co-occur. This contrasted with patterns of predator-predator or predator-prey co-occurrences that either aggregated to their prey or were weak and more scattered. These patterns could not be explained by either competition for resources or body size differences. Procrustean methods indicated that the networks were temporally dynamic, consistently achieving rates of turnover > 60%. A negative relationship was found between decreasing predator-prey co-occurrence in the network and the number of prey positives in the guts of those predators. For large polyphagous beetles, the closer they were to their prey at the field scale, the more likely they were to have eaten them. This simple underlying relationship suggests that spatial co-occurrence networks can be used to predict feeding behaviour and could make a valuable contribution to food web structuring
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Protecting an ecosystem service: approaches to understanding and mitigating threats to wild insect pollinators
No full textInsect pollination constitutes an ecosystem service of global importance, providing significant economic and aesthetic benefits as well as cultural value to human society, alongside vital ecological processes in terrestrial ecosystems. It is therefore important to understand how insect pollinator populations and communities respond to rapidly changing environments if we are to maintain healthy and effective pollinator services. This chapter considers the importance of conserving pollinator diversity to maintain a suite of functional traits and provide a diverse set of pollinator services. We explore how we can better understand and mitigate the factors that threaten insect pollinator richness, placing our discussion within the context of populations in predominantly agricultural landscapes in addition to urban environments. We highlight a selection of important evidence gaps, with a number of complementary research steps that can be taken to better understand: (i) the stability of pollinator communities in different landscapes in order to provide diverse pollinator services; (ii) how we can study the drivers of population change to mitigate the effects and support stable sources of pollinator services and (iii) how we can manage habitats in complex landscapes to support insect pollinators and provide sustainable pollinator services for the future. We advocate a collaborative effort to gain higher quality abundance data to understand the stability of pollinator populations and predict future trends. In addition, for effective mitigation strategies to be adopted, researchers need to conduct rigorous field testing of outcomes under different landscape settings, acknowledge the needs of end-users when developing research proposals and consider effective methods of knowledge transfer to ensure effective uptake of actions
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