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Complex Landscapes (complex + landscapes)
Selected AbstractsMorphological clines in dendritic landscapesFRESHWATER BIOLOGY, Issue 9 2007A. CHAPUT-BARDY Summary 1. In complex landscapes such as river networks, organisms usually face spatio-temporal heterogeneity and gradients in geomorphological, water, ecological or landscape characteristics are often observed at the catchment scale. These environmental variables determine developmental conditions for larval stages of freshwater insects and influence adult phenotypic characteristics. Environmental clines are therefore expected to generate morphological clines. Such a process has the potential to drive gradual geographical change in morphology-dependent life history traits, such as dispersal. 2. We studied the influence of aquatic and terrestrial environmental factors on morphological variations in Calopteryx splendens across the Loire drainage. To investigate these effects we took explicitly into account the hierarchical structure of the river network. 3. We analysed eight morphological traits. Results showed significant body size variation between tributaries and the presence of a morphological cline at the drainage scale. We observed an effect of pH and water temperature on body size. Individuals in downstream sites were larger than individuals in upstream sites, and adults whose larval stages were exposed to alkaline pH and high temperatures during summer were larger. 4. Body size affects flight abilities in insects. Thus, our results suggest that morphological clines may generate an asymmetric dispersal pattern along the downstream,upstream axis, downstream populations dispersing farther than upstream ones. Such a process is expected to influence population genetic structure at the drainage scale if larval drift and floods do not balance an asymmetrical dispersal pattern of adults along the downstream,upstream gradient. To assess the influence of environmental gradients on the variation of life history traits it is important to understand the population biology of freshwater insects, and more generally of riverine organisms. It is also essential to integrate such data in conservation or restoration programmes. [source] Disability and Development: Different Models, Different PlacesGEOGRAPHY COMPASS (ELECTRONIC), Issue 3 2007Cheryl McEwan Debates about disability within geography, as well as in disability studies more generally, have been largely urban, Anglophone and Western-centric. Not only have industrialised societies remained the predominant focus of attention, but the debates themselves are rooted within an often unacknowledged Western context. In the light of this, this article aims to bring together debates about disability and development, which have until relatively recently tended to be mutually exclusive, and provides a critical review of recent debates about disability issues in developing countries. By doing so, it furthers debates about the significance of geography in disability studies, challenges the Western-centric focus of disability models and extends understanding of the shifting and complex landscapes of disability in developing countries. [source] Modelling blowing snow redistribution to prairie wetlandsHYDROLOGICAL PROCESSES, Issue 18 2009X. Fang Abstract Blowing snow transports and sublimates a substantial portion of the seasonal snowfall in the prairies of western Canada. Snow redistribution is an important feature of prairie hydrology as deep snowdrifts provide a source of meltwater to replenish ponds and generate streamflow in this dry region. The spatial distribution of snow water equivalent in the spring is therefore of great interest. A test of the distributed and aggregated modelling strategies for blowing snow transport and sublimation was conducted at the St. Denis National Wildlife Area in the rolling, internally drained prairie pothole region east of Saskatoon, Saskatchewan, Canada. A LiDAR-based DEM and aerial photograph-based vegetation cover map were available for this region. A coupled complex windflow and blowing snow model was run with 262,144 6 m × 6 m grid cells to produce spatially distributed estimates of seasonal blowing snow transport and sublimation. The calculation was then aggregated to seven landscape units that represented the major influences of surface roughness, topography and fetch on blowing snow transport and sublimation. Both the distributed and aggregated simulations predicted similar end-of-winter snow water equivalent with substantial redistribution of blowing snow from exposed sparsely vegetated sites across topographic drainage divides to the densely vegetated pothole wetlands. Both simulations also agreed well with snow survey observations. While the distributed calculations provide a fascinating and detailed visual image of the interaction of complex landscapes and blowing snow redistribution and sublimation, it is clear that blowing snow transport and sublimation calculations can be successfully aggregated to the spatial scale of the major landscape units in this environment. This means that meso and macroscale hydrological models can represent blowing snow redistribution successfully in the prairies. Copyright © 2009 John Wiley & Sons, Ltd. [source] Diffusion models for animals in complex landscapes: incorporating heterogeneity among substrates, individuals and edge behavioursJOURNAL OF ANIMAL ECOLOGY, Issue 5 2008John D. Reeve Summary 1Animals move commonly through a variety of landscape elements and edges in search of food, mates and other resources. We developed a diffusion model for the movement of an insect herbivore, the planthopper Prokelisia crocea, that inhabits a landscape composed of patches of its host plant, prairie cordgrass Spartina pectinata, embedded in a matrix of mudflat or smooth brome Bromus inermis. 2We used mark,release,resight experiments to quantify planthopper movements within cordgrass,brome and cordgrass,mudflat arenas. A diffusion model was then fitted that included varying diffusion rates for cordgrass and matrix, edge behaviour in the form of a biased random walk and heterogeneity among planthoppers (sessile vs. mobile). The model parameters were estimated by maximum likelihood using the numerical solution of the diffusion model as a probability density. Akaike's information criterion (AIC) values were used to compare models with different subsets of features. 3There was clear support for models incorporating edge behaviour and both sessile and mobile insects. The most striking difference between the cordgrass,brome and cordgrass,mudflat experiments involved edge behaviour. Planthoppers crossed the cordgrass,brome edge readily in either direction, but traversed the cordgrass,mudflat edge primarily in one direction (mudflat to cordgrass). Diffusion rates were also significantly higher on mudflat than for cordgrass and brome. 4The differences in behaviour for cordgrass,brome vs. cordgrass,mudflat edges have implications for the connectivity of cordgrass patches as well as their persistence. Higher dispersal rates are expected between cordgrass patches separated by brome relative to mudflat, but patches surrounded by mudflat appear more likely to persist through time. 5The experimental design and diffusion models used here could potentially be extended to any organism where mass mark,recapture experiments are feasible, as well as complex natural landscapes. [source] Migrant women in male-dominated sectors of the labour market: a research agendaPOPULATION, SPACE AND PLACE (PREVIOUSLY:-INT JOURNAL OF POPULATION GEOGRAPHY), Issue 1 2008Parvati Raghuram Abstract There is a growing literature on female labour migration, but much of this focuses on women who move to work in labour-market sectors where a large proportion of workers are women. This paper argues that there has been much less study of women who migrate to work in male-dominated sectors of the labour market, and explores the nature of this lacuna within research on female migration. It then highlights the increasing presence of women migrants in the ICT sector as one example of an area that has received little study. Finally, the paper explores some reasons why a study of female migrant's experiences in male-dominated sectors of the labour market is important, and what it can add to existing research on female migration more generally. In particular, it urges us to view gender as it intersects and overlaps with other social divisions to produce complex landscapes of female mobility. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||