Aquatic landscape change,extirpations, and introductions in the Chicago Region

Urban Ecosystems - Prior to European settlement, swamps, marshes, lakes, and streams were the major landscape features of the Chicago region. Much of this has been altered or lost in the past...     

Explanatory models for disability: perspectives of health providers working in Malawi

Health providers’ understanding of disability determines how disabled people are treated, and hence it is imperative to address conceptualisations of disability, as this will contribute to better opportunities and realisation of human rights for disabled people. This article will use data from a qualitative study exploring conceptualisations of disability by 22 health service providers from the total health care system in Malawi, including the professional sector (e.g. medical doctors and nurses) and the folk sector (healers and indigenous practices). We will discuss how these perceptions influence the lives of disabled people, using the case of a health service user with physical and speech impairment as an example. Our data show that health providers largely conceptualise disability according to the medical model for disability, contributing to the exclusion of disabled people. The bio-psycho-social model for disability, largely absent as an explanatory model for disability among our informants, is the most inclusive and rights based.     

Direct and indirect effects of human population density and land use on physical features and invertebrates of Iowa (U.S.A.) streams

To improve understanding of human impacts on headwater stream condition, we quantified relationships between human, terrestrial landscape, and stream system variables in 29 central Iowa watersheds. Across study watersheds, between 0 and 100 % of total land area was characterized as “urban” (developed and barren land), whereas cultivated land constituted between 0 and 71 % of watershed area. Several variables were measured for each stream and associated watershed. Strengths of correlative relationships were used to select variables for path analysis, which we used to gain insight into factors affecting stream condition by evaluating direct and indirect effects of human system variables, terrestrial landscape variables, and physical stream variables on stream invertebrates. Results indicated that in predominantly urban watersheds, contaminant inputs to streams (measured by streamwater conductivity) negatively affected invertebrates, including EPT taxa (Ephemeroptera, Plecoptera, Trichoptera), and streamwater contaminant concentrations increased with impervious surface and human population density in the watershed. In rural watersheds, high streamwater nitrogen concentrations associated with cultivated land were related to declines in invertebrate taxon richness. Independent of land use, invertebrate abundance and taxonomic diversity were positively related to coarse substrate abundance on the streambed. Additionally, stream flow (discharge) increased with watershed area, which in turn increased invertebrate taxonomic diversity. Apparently, mechanisms responsible for human impacts on stream condition in central Iowa depend on dominant land use in the watershed. Additionally, stream ecosystems with high quality benthic habitat, and those located in large watersheds with greater flow, appear to be more resilient to land use effects.