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Rapid urbanization has become an area of crucial concern in conservation owing to the radical changes in habitat structure and loss of species engendered by urban and suburban development. Here, we draw on recent mechanistic ecological studies to argue that, in addition to altered habitat structure, three major processes contribute to the patterns of(More)
A detailed fixed nitrogen (N) mass balance was constructed for the Central Arizona–Phoenix (CAP) ecosystem. Input of fixed N input to the ecosystem was 98 Gg y Ϫ1. Of this, humans deliberately imported or mediated the fixation of 51 Gg N y Ϫ1 ; combustion processes added another 36 Gg y Ϫ1. Fixation by desert plants, wet deposition, and surface water input(More)
Urban ecosystems are profoundly modified by human activities and thereby provide a unique ''nat-ural laboratory'' to study potential ecosystem responses to anthropogenic environmental changes. Because urban environments are now affected by urban heat islands, carbon dioxide domes, and high-level nitrogen deposition, to some extent they portend the future of(More)
We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well as for the desert and urban sites separately. Concentrations of both NO 3-N and NH 4-N were markedly higher(More)
When rat posterior pituitary glands were stimulated by a high concentration of potassium, a peak of cyclic AMP and a peak of cyclic GMP were detected after 0.5 min and 1 min, respectively, whereas the rate of release of vasopressin was maximal only after 2 min. When calcium was omitted from the medium, no significant changes in cyclic nucleotide levels were(More)
A neighborhood's ability to act collectively to address common problems is an indicator of its well-being (Ferguson and Dickens 1999). Today, understanding why individuals in some neighborhoods undertake civic actions is increasingly important as more residential communities opt for gated separation; formalize their neighborhood relationships and rights via(More)
Ecologists increasingly use plot-scale data to inform research and policy related to regional and global environmental change. For soil chemistry research, scaling from the plot to the region is especially difficult due to high spatial variability at all scales. We used a hierarchical Bayesian model of plot-scale soil nutrient pools to predict storage of(More)
Soil chemistry Nitrate-N content of the upper soil profile (0-10 cm depth) at the sites, grouped according to the major land uses. Urban and agricultural soils have markedly higher N contents. The proposed method uses a number of key components as equal contributors to the index. Another possibility is to create sub-indices that are constructs of abstract(More)