862 research outputs found

    Reading history through constructivist eyes

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    Desde el final de la Guerra Fr√≠a, se ha producido un resurgir del inter√©s por la historia por parte de los estudiosos de Relaciones Internacionales. Los constructivistas han estado a la cabeza de este redescubrimiento, recurriendo a la investigaci√≥n hist√≥rica para destacar el significado contingente y la evoluci√≥n de una mir√≠ada de pr√°cticas internacionales, procesos y estructuras sociales. Sin embargo, ¬Ņen qu√© medida est√° este trabajo guiado por una filosof√≠a de la historia distinta, sea expl√≠cita o impl√≠cita?, ¬Ņleen los constructivistas la historia de una manera particular? Y si as√≠ fuera, ¬Ņcu√°les son los contornos de su enfoque? Este art√≠culo aborda estas cuestiones, argumentando que la historia constructivista es esencialmente ‚Äúskinneriana‚ÄĚ en naturaleza, excluy√©ndola por una parte de la historia realista-materialista y, por otra, de la historia de las ideas. Para ilustrar este enfoque, terminar√© con una breve lectura constructivista de la crisis constitucional que asol√≥ al Imperio espa√Īol tras la invasi√≥n napole√≥nica de 1808Since the end of the Cold War there has been a renaissance in the study of history by International Relations scholars. Constructivists have been at the forefront of this rediscovery, turning to historical inquiry to highlight the contingent meaning and evolution of a myriad of international practices, processes, and social structures. To what extent, however, is this work informed by a distinctive philosophy of history, explicit or implicit? Do constructivists read history in a particular way? If so, what are the contours of their approach? This article takes up these questions, arguing that constructivist history is essentially ‚ÄėSkinnerian‚Äô in nature, marking it off from realist-materialist histories, on the one hand, and histories of ideas, on the other. To illustrate this approach I end with a brief constructivist reading of the constitutional crisis that beset the Spanish Empire in the aftermath of the Napoleonic invasion and usurpation in 180

    Process of stop-motion and motion graphics animation for The Amazing European Bison Journey clip

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    The Amazing European Bison Journey prototype clip shows an extract of the timeline of this species coming back from their near disappearance. It starts in the BiaŇāowieŇľa Forest in Poland in 1919, when they went extinct in the wild. And runs up to 2013 in Zuid-Kennemerland in the Nether-lands, where an initial herd of 6 European bison, translocated in 2007 from Poland, had quadrupled to 24 individuals living in the Dutch dunes. The process of production of this animated documentary is de-scribed starting with the ecological research required. Review of literature, contact with specialist scientists and visitation of Poland and the Netherlands are some of the starting points of the process. Subsequently, the preparation for the animation is described. The initial storyboard was constructed out of the preceding ecological research. Afterwards, the development of the script and its respective narration was recorded. The construction of the sets, props and characters is described; specific emphasis is given to the construction of the European bison. Finally, the assemblage of all the elements is explained and the final results of the animation prototype are revealed. This animation forms part of a broader project, which has research into the effectiveness of a set of visual communication formats at its core, and uses rewilding as its ecological platform. A range of animations, infographics and virtual reality pieces will be eventually compared for their effectiveness using several communication research tools

    Small herbivores and abiotic heterogeneity promote trait variation of a saltmarsh plant in local communities

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    Intraspecific trait variation (ITV) enables plants to respond to global changes. However, causes for ITV, especially from biotic components such as herbivory, are not well understood. We explored whether small vertebrate herbivores (hares and geese) impact ITV of a dominant clonal plant (Elytrigia atherica) in local communities. Moreover, we looked at the relative importance of their direct (e.g., selective grazing) and indirect effects (altering genotypic richness/diversity and abiotic environment) on ITV. We used exclosures at two successional stages in a Dutch saltmarsh, where grazing pressure at the early successional stage was ca. 1.5 times higher than that of the intermediate successional stage. We measured key functional traits of E. atherica including height, aboveground biomass, flowering (flower or not), specific leaf area, and leaf dry matter content in local communities (1 m × 1 m plots) inside and outside the exclosures. We determined genotypic richness and diversity of each plant using molecular markers. We further measured abiotic variations in topography and clay thickness (a proxy for soil total nitrogen). Structural equation models revealed that small herbivores significantly promoted ITV in height and flowering at the early successional stage, while they marginally promoted ITV in height at the intermediate successional stage. Moreover, the direct effects of herbivores played a major role in promoting ITV. Small herbivores decreased genotypic diversity at the intermediate successional stage, but genotypic richness and diversity did not impact ITV. Small herbivores did not alter topographic variation and variation in clay thickness, but these variations increased ITV in all traits at the early successional stage. Small herbivores may not only impact trait means in plants as studies have shown but also their ITV

    Long-term management is needed for conserving plant diversity in a Wadden Sea salt marsh

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    Evaluation of long-term management regimes is important for guiding biodiversity conservation in salt marshes. However, such long-term experiments are sparse. Using a 46-year experiment in a salt marsh, we evaluated long-term effects of eight different management regimes (treatments; control, grazing, mowing, and their combinations) on the expansion of a late successional plant species (Elytrigia atherica), plant species richness and diversity, and community composition (species identities and dominance structure). Results show that E. atherica expanded strongly over time in the control treatment (without grazing or mowing) while plant species richness and diversity declined substantially. By contrast, E. atherica was greatly suppressed while plant species richness and diversity remained relatively unchanged in all other treatments except for the mowing, where species richness declined in the late season mowing treatment and plant diversity declined after 17 years in the both early and late season mowing treatment. Therefore, all management types except for the mowing were effective in conserving plant diversity. The trends for change in species identities reversed: change in species identities accumulated in the control treatment and exceeded that of other treatments 15 years after the start of the experiment. This suggests that results based on shorter-term (< 15 years) experiments may provide misleading conservation recommendations. Also, trends for change in dominance structure (taking abundance into account) were substantially different from those for species identities. Our results highlight the importance of long-term monitoring for guiding conservation management, and that monitoring should not only focus on the number of species but also community composition, to fully identify critical changes.Fil: Chen, Qingqing. University of Groningen; Países BajosFil: Bakker, Jan P.. University of Groningen; Países BajosFil: Alberti, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Smit, Christian. University of Groningen; Países Bajo

    Fitness benefits of the fruit fly <i>Rhagoletis alternata</i> on a non-native rose host

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    Many species have been introduced worldwide into areas outside their natural range. Often these non-native species are introduced without their natural enemies, which sometimes leads to uncontrolled population growth. It is rarely reported that an introduced species provides a new resource for a native species. The rose hips of the Japanese rose, Rosa rugosa, which has been introduced in large parts of Europe, are infested by the native monophagous tephritid fruit fly Rhagoletis alternata. We studied differences in fitness benefits between R. alternata larvae using R. rugosa as well as native Rosa species in the Netherlands. R. alternata pupae were larger and heavier when the larvae fed on rose hips of R. rugosa. Larvae feeding on R. rugosa were parasitized less frequently by parasitic wasps than were larvae feeding on native roses. The differences in parasitization are probably due to morphological differences between the native and non-native rose hips: the hypanthium of a R. rugosa hip is thicker and provides the larvae with the possibility to feed deeper into the hip, meaning that the parasitoids cannot reach them with their ovipositor and the larvae escape parasitization. Our study shows that native species switching to a novel non-native host can experience fitness benefits compared to the original native host

    Nurse plants, tree saplings and grazing pressure: changes in facilitation along a biotic environmental gradient

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    Current conceptual models predict that an increase in stress shifts interactions between plants from competitive to facilitative; hence, facilitation is expected to gain in ecological importance with increasing stress. Little is known about how facilitative interactions between plants change with increasing biotic stress, such as that incurred by consumer pressure or herbivory (i.e. disturbance sensu Grime). In grazed ecosystems, the presence of unpalatable plants is reported to protect tree saplings against cattle grazing and enhance tree establishment. In accordance with current conceptual facilitation-stress models, we hypothesised a positive relationship between facilitation and grazing pressure. We tested this hypothesis in a field experiment in which tree saplings of four different species (deciduous Fagus sylvatica, Acer pseudoplatanus and coniferous Abies alba, Picea abies) were planted either inside or outside of the canopy of the spiny nurse shrub Rosa rubiginosa in enclosures differing in grazing pressure (low and high) and in exclosures. During one grazing season we followed the survival of the different tree saplings and the level of browsing on these; we also estimated browsing damage to the nurse shrubs. Shrub damage was highest at the higher grazing pressure. Correspondingly, browsing increased and survival decreased in saplings located inside the canopy of the shrubs at the high grazing pressure compared to the low grazing pressure. Saplings of both deciduous species showed a higher survival than the evergreens, while sapling browsing did not differ between species. The relative facilitation of sapling browsing and sapling survival - i.e. the difference between saplings inside and outside the shrub canopy - decreased at high grazing pressure as the facilitative species became less protective. Interestingly, these findings do not agree with current conceptual facilitation-stress models predicting increasing facilitation with abiotic stress. We used our results to design a conceptual model of facilitation along a biotic environmental gradient. Empirical studies are needed to test the applicability of this model. In conclusion, we suggest that current conceptual facilitation models should at least consider the possibility of decreasing facilitation at high levels of stres
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