55 research outputs found

    Does Conservation Planning Matter in a Dynamic and Uncertain World?

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    We show that while comprehensive reserve network design is best when the entire network can be implemented immediately, when conservation investments must be staged over years, such solutions actually may be sub-optimal in the context of biodiversity loss and uncertainty

    Effects of large-scale heathland management on thermal regimes and predation on adders Vipera berus

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    Management prescriptions for species of conservation concern often focus on creating appropriate habitat conditions, but the spatial scales over which these actions are applied can potentially impact their success. In Northwestern Europe, preventing further loss of lowland heathland through successional changes often involves the mechanical removal of vegetation, creating large blocks of open homogenous habitat. We investigate the influence of this broad-scale habitat management on a heathland specialist, the adder Vipera berus. By deploying temperature loggers and Plasticine adder models in heathland areas with and without complex vegetation cover, we show that (1) cleared areas lack both the temperature variation adders need to thermoregulate effectively and suitable refuges from dangerously high summer temperatures, and (2) attacks by dogs and trampling by grazing livestock are significantly more frequent in cleared areas and closer to footpaths. Habitat management strategies that retain some structural complexity of vegetation within cleared areas, and diverting footpaths away from cleared areas and/or strategic placement of barrier hedging around these areas could potentially reduce the exposure of adders to high predation risk and thermal extremes

    Social environmental impacts on survey cooperation

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    Social environmental influences on survey cooperation are explored using data from six national household surveys in the United States matched to 1990 decennial census data. Consistent with the past literature on prosocial behavior, cooperation rates in these six surveys are found to be lower in urban, densely populated, high crime rate areas. Measures of social cohesion show no evidence of influencing cooperation. The influence of the environmental variables is then observed after introducing statistical controls for household structure, race, age of household members, presence of children, and socioeconomic attributes of households. Over half of the measured influence of the environmental variables is explained by these household-level attributes. These findings have practical import for survey administrators and are informative for the construction of a theory of survey participation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43559/1/11135_2004_Article_BF00153986.pd

    A Survey of mid and large bodied mammals in NĂșcleo Caraguatatuba, Serra do Mar State Park, Brazil

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    NĂłs aplicamos tĂ©cnicas de amostragem complementares para obter uma lista de espĂ©cies de mamĂ­feros de mĂ©dio e grande porte no NĂșcleo Caraguatatuba, Parque Estadual da Serra do Mar, Brasil. As amostragens de campo realizaram-se nos meses de Maio e Setembro de 2011. Utilizou-se, censo ao longo de transectos (212,4 km), armadilhas fotogrĂĄficas (223,2 armadilhas-dias) e armadilhas de pegadas (478 armadilhas-dias). Foram obtidos registros de 18 espĂ©cies, pertencentes a 14 famĂ­lias e oito ordens. NĂłs registramos a presença de sete espĂ©cies consideradas ameaçadas no Estado de SĂŁo Paulo, incluindo primatas (Brachyteles arachnoides), Artiodactyla (Mazama americana e Tayassu pecari), Carnivora (Leopardus pardalis, Leopardus tigrinus e Puma concolor) e Perissodactyla (Tapirus terrestris). Com base em numa extrapolação da riqueza de espĂ©cies (First order jackknife) nĂłs prevemos que existem entre 19 e 32 espĂ©cies de mamĂ­feros de mĂ©dio e grande porte no NĂșcleo. Nosso Mammal Priority Index classificou o NĂșcleo Caraguatatuba como uma ĂĄrea de importĂąncia mĂ©dia para a conservação de mamĂ­feros de mĂ©dio e grande porte na Mata AtlĂąntica. Combinado com o nĂșmero e a diversidade de espĂ©cies registradas, nossos resultados demonstram que este NĂșcleo Ă© uma ĂĄrea importante para a conservação de mamĂ­feros no Estado.We applied complementary survey techniques to obtain a baseline species list of mid and large bodied mammals in NĂșcleo Caraguatatuba, Serra do Mar State park, Brazil. Between May and September 2011 we surveyed the community of mid and large bodied mammals using diurnal line transect census (212.4 km), camera-traps (223.2 camera-trap days) and track-stations (478 track-station days). A total of 18 species were recorded from 14 families in eight orders. We recorded the presence of seven species considered threatened in the State of SĂŁo Paulo, including Primates (Brachyteles arachnoides), Artiodactyla (Mazama cf. americana and Tayassu pecari), Carnivora (Leopardus pardalis, Leopardus tigrinus and Puma concolor) and Perissodactyla (Tapirus terrestris). Based on extrapolated (First order jackknife) species richness estimates we predict that there are between 19 and 32 species of mid and large bodied mammals in the NĂșcleo. Our revised Mammal Priority Index ranked NĂșcleo Caraguatatuba as being of medium overall importance for the conservation of mid and large bodied mammals in the Atlantic Forest. Combined with the number and diversity of species recorded, our results demonstrate that this NĂșcleo is an important area for mammal conservation

    Profitability of dairy farms 1984-1985, and future trends

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    SIGLEAvailable from British Library Document Supply Centre- DSC:3465.063(WSAC-CR--29) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

    Influence of annealing and interfacial roughness on the performance of bilayer donor/acceptor polymer photovoltaic devices

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    Through controlled annealing of planar heterojunction (bilayer) devices based on the polyfluorene copolymers poly(9,9-dioctylfluorene-co-bis(N,Nâ€Č-(4,butylphenyl))bis(N,Nâ€Č-phenyl-1,4-phenylene)diamine) (PFB) and poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) we study the influence of interface roughness on the generation and separation of electron–hole pairs at the donor/acceptor interface. Interface structure is independently characterized by resonant soft X-ray reflectivity with the interfacial width of the PFB/F8BT heterojunction observed to systematically increase with annealing temperature from 1.6 nm for unannealed films to 16 nm with annealing at 200 °C for ten minutes. Photoluminescence quenching measurements confirm the increase in interface area by the three-fold increase in the number of excitons dissociated. Under short-circuit conditions, however, unannealed devices with the sharpest interface are found to give the best device performance, despite the increase in interfacial area (and hence the number of excitons dissociated) in annealed devices. The decrease in device efficiency with annealing is attributed to decreased interfacial charge separation efficiency, partly due to a decrease in the bulk mobility of the constituent materials upon annealing but also (and significantly) due to the increased interface roughness. We present results of Monte Carlo simulations that demonstrate that increased interface roughness leads to lower charge separation efficiency, and are able to reproduce the experimental current-voltage curves taking both increased interfacial roughness and decreased carrier mobility into account. Our results show that organic photovoltaic performance can be sensitive to interfacial order, and heterojunction sharpness should be considered a requirement for high performance devices
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