548 research outputs found

    Homogenisation of Monotone Parabolic Problems with Several Temporal Scales: The Detailed arXiv e-Print Version

    Full text link
    In this paper we homogenise monotone parabolic problems with two spatial scales and finitely many temporal scales. Under a certain well-separatedness assumption on the spatial and temporal scales as explained in the paper, we show that there is an H-limit defined by at most four distinct sets of local problems corresponding to slow temporal oscillations, slow resonant spatial and temporal oscillations (the "slow" self-similar case), rapid temporal oscillations, and rapid resonant spatial and temporal oscillations (the "rapid" self-similar case), respectively.Comment: 57 pages, no figures. Intended as a detailed version of a journal paper. Revised with some added reference

    Integrating animal tracking datasets at a continental scale for mapping Eurasian lynx habitat

    Get PDF
    Aim The increasing availability of animal tracking datasets collected across many sites provides new opportunities to move beyond local assessments to enable detailed and consistent habitat mapping at biogeographical scales. However, integrating wildlife datasets across large areas and study sites is challenging, as species' varying responses to different environmental contexts must be reconciled. Here, we compare approaches for large-area habitat mapping and assess available habitat for a recolonizing large carnivore, the Eurasian lynx (Lynx lynx).LocationEurope.Methods We use a continental-scale animal tracking database (450 individuals from 14 study sites) to systematically assess modelling approaches, comparing (1) global strategies that pool all data for training versus building local, site-specific models and combining them, (2) different approaches for incorporating regional variation in habitat selection and (3) different modelling algorithms, testing nonlinear mixed effects models as well as machine-learning algorithms.Results Testing models on training sites and simulating model transfers, global and local modelling strategies achieved overall similar predictive performance. Model performance was the highest using flexible machine-learning algorithms and when incorporating variation in habitat selection as a function of environmental variation. Our best-performing model used a weighted combination of local, site-specific habitat models. Our habitat maps identified large areas of suitable, but currently unoccupied lynx habitat, with many of the most suitable unoccupied areas located in regions that could foster connectivity between currently isolated populations.Main Conclusions We demonstrate that global and local modelling strategies can achieve robust habitat models at the continental scale and that considering regional variation in habitat selection improves broad-scale habitat mapping. More generally, we highlight the promise of large wildlife tracking databases for large-area habitat mapping. Our maps provide the first high-resolution, yet continental assessment of lynx habitat across Europe, providing a consistent basis for conservation planning for restoring the species within its former range

    Paying for an Endangered Predator Leads to Population Recovery

    Get PDF
    Keeping viable predator populations on a human-dominated planet will require innovative approaches that promote local coexistence with human activities. Conservation performance payments, which are linked specifically to the production of a desired environmental output, have received increasing attention but their effectiveness in predator conservation remains undocumented. Here, we show that paying Sami reindeer herders for wolverine (Gulo gulo) reproductions has been instrumental in the recovery of wolverines in Sweden. Adult female wolverines were significantly less exposed to illegal killing and this allowed the population to more than double in a decade. We argue that this program provides protection for adult female wolverines through a combination of direct monetary value and indirect protection because of monitoring activities. The program's success, even in a system where livestock is the main prey for the predator, reveals an exceptional potential for future implementations in large carnivore conservation

    Insatsen ingen ville samordna

    Get PDF
    During Sweden’s commitment in the international intervention in Afghanistan the policymaking regarding the civil-military coordination measures failed. The Swedish government stated and emphasized in their appropriations and strategies that their intent – cooperation and synergies – were a crucial point for mission success. Even so, the government didn´t take any actions clarifying how their intent should be met. Who, how and why were questions left unanswered from the government to the authorities and personnel on the field level in Afghanistan. The research question guiding us through this thesis is: Why did the government fail in the implementation process of the civil-military cooperation on the field level in Afghanistan? To narrow down the extent of the thesis the author has chosen three management theories – decentralization, legitimacy and implementation – incorporated in three hypotheses. After using these three hypotheses as an analytic tool the author has come to the following conclusions: Because of traditional Swedish governance and the lack of an appointed process manager, the questions who, how and why could only be answered by authorities and field personnel from their own perspective. Because of these circumstances there never was a coherent Swedish contribution regarding civil-military cooperation

    Wolverine denning behaviour and its implications for monitoring reproductive females

    Get PDF
    Knowledge about the number of reproductive females is important for monitoring population dynamics, and can be critical for managing human-wildlife conflicts. For wolverines Gulo gulo, counts of reproductive females is the basis for estimates of population size in Scandinavia, as well as a key measure for compensation payments to Sami reindeer-herders in Sweden. However, documenting wolverine reproductive events in the field is challenging and requires knowledge of female denning behaviour. Furthermore, females may shift den sites, presenting difficulties in determining whether two den sites belong to the same or two neighbouring females. In this study, we used data from 18 GPS-collared wolverine females, monitored intensively during the denning season (15 February-31 May) in 2004-2014, to provide baseline information on denning behaviour. We documented reproductive events in 32 of 54 potential denning seasons, and identified a total of 245 den sites. Females used 8.8 +/- 8.5 (mean +/- SD) den sites per denning season (median = 6, range: 1-28). The number of den site shifts, the distance between subsequent den sites, and the time and distance females spent away from a den site increased during the denning season; while distances between neighbouring females' den sites remained constant. From late April, the distance between consecutive den sites used by the same female overlapped with distances between neighbouring females' den sites, resulting in increased uncertainty regarding whether two den sites belonged to one or two females. Using Bayesian modelling we calculated probabilities that two den sites belonged to the same female, or neighbouring females, conditional on the time of season and the distance between den sites. These findings will allow the monitoring program to adapt its methods for determining if multiple den sites belong to one or two reproductive events, using seasonally-dynamic threshold based on an understanding of wolverine denning behaviour

    Large grazing birds and agriculture—predicting field use of common cranes and implications for crop damage prevention

    Get PDF
    Increasing numbers of previously threatened large grazing birds (cranes, geese and swans) are causing crop damage along their flyways worldwide. For example, the number of reported incidents of crop damage caused by common cranesGrus grus, followed by regulated inspections and governmental compensation in Sweden, has increased over the last few decades and was valued at ∼200,000 Euros in 2012. Consequently, their impact on agriculture is escalating which raises the need for evidence-informed preventative strategies. We surveyed arable fields for autumn staging common cranes in an area surrounding a wetland reserve in Sweden. We assessed the following factors in relation to the probability of cranes being present on fields: crop stage, crop type, distance to roost site, time of day, field size and time since harvest. Stubble fields had the highest probability of crane presence, progressively decreasing through grassland and grazing grounds, bare soil to growing crop. A stubble field at 5km from a roost site had a predicted probability (95% CI) of hosting cranes of 0.25 (0.19–0.32). The probability of cranes visiting a field was linearly and negatively related to distance to the roost site. For example, the probability of crane presence increased from 0.05 (0.03–0.07) to 0.09 (0.06–0.15) when distance decreased from 5 to 1km. At stubble fields, the probability of crane presence decreased with time since harvest and was highest for barley with progressively lower probability on wheat and oat. Illustrative scenario predictions developed from the models demonstrated that probability of crane presence could be high, 0.60 (0.42–0.77), if all favorable factors were combined (e.g. barley stubble, 1 day after harvest, 1km from roost site). Given the existing framework of international conventions and prohibition of culling, there is a need for preventative strategies to reduce crop damage. Based on our results, such strategies should focus on providing cereal stubbles as diversionary fields, especially close to wetland roosting sites. Stubble field availability can be achieved by careful crop rotation planning. We suggest that crop rotation and time of harvest should be added to flyway management plans recently developed for some large grazing bird species to facilitate stable co-existence between conservation practices and agricultural interests

    Порівняльний аналіз зовнішньоекономічної функції Російської Федерації

    Get PDF
    Electronic-grade GaN (0001) epilayers have been grown directly on Al2O3 (0001) substrates by reactive DC-magnetron sputter epitaxy (MSE) from a liquid Ga sputtering target in an Ar/N2 atmosphere. The as-grown GaN epitaxial film exhibit low threading dislocation density on the order of ≤ 1010 cm-2 obtained by transmission electron microscopy and modified Williamson-Hall plot. X-ray rocking curve shows narrow fullwidth at half maximum (FWHM) of 1054 arcsec of the 0002 reflection. A sharp 4 K photoluminescence peak at 3.474 eV with a FWHM of 6.3 meV is attributed to intrinsic GaN band edge emission. The high structural and optical qualities indicate that MSEgrown GaN epilayers can be used for fabricating high-performance devices without the need of any buffer layer.On the day of the defence date the status of this article was: Manuscript.Original Publication:Muhammad Junaid, Ching-Lien Hsiao, Justinas Palisaitis, Jens Jensen, Per Persson, Lars Hultman and Jens Birch, Electronic-grade GaN(0001)/Al2O3(0001) grown by reactive DC-magnetron sputter epitaxy using a liquid Ga target, 2011, Applied Physics Letters, (98), 14, 141915.http://dx.doi.org/10.1063/1.3576912Copyright: American Institute of Physicshttp://www.aip.org

    Recolonization following past persecution questions the importance of persistent snow cover as a range limiting factor for wolverines

    Get PDF
    Globally, climate is changing rapidly, which causes shifts in many species' distributions, stressing the need to understand their response to changing environmental conditions to inform conservation and management. Northern latitudes are expected to experience strongest changes in climate, with milder winters and decreasing snow cover. The wolverine (Gulo gulo) is a circumpolar, threatened carnivore distributed in northern tundra, boreal, and subboreal habitats. Previous studies have suggested that wolverine distribution and reproduction are constrained by a strong association with persistent spring snow cover. We assess this hypothesis by relating spatial distribution of 1589 reproductive events, a fitness-related proxy for female reproduction and survival, to snow cover over two decades. Wolverine distribution has increased and number of reproductive events increased 20 times in areas lacking spring snow cover during our study period, despite low monitoring effort where snow is sparse. Thus, the relationship between reproductive events and persistent spring snow cover weakened during this period. These findings show that wolverine reproductive success and hence distribution are less dependent on spring snow cover than expected. This has important implications for projections of future habitat availability, and thus distribution, of this threatened species. Our study also illustrates how past persecution, or other factors, that have restricted species distribution to remote areas can mask actual effects of environmental parameters, whose importance reveals when populations expand beyond previously restricted ranges. Overwhelming evidence shows that climate change is affecting many species and ecological processes, but forecasting potential consequences on a given species requires longitudinal data to revisit hypotheses and reassess the direction and magnitude of climate effects with new data. This is especially important for conservation-oriented management of species inhabiting dynamic systems where environmental factors and human activities interact, a common scenario for many species in different ecosystems around the globe
    corecore