Learn More
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)
Spatial variation in plant diversity has been attributed to heterogeneity in resource availability for many ecosystems. However, urbanization has resulted in entire landscapes that are now occupied by plant communities wholly created by humans, in which diversity may reflect social, economic, and cultural influences in addition to those recognized by(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−1. Of this, humans deliberately imported or mediated the fixation of 51 Gg N y−1; combustion processes added another 36 Gg y−1. Fixation by desert plants, wet deposition, and surface water input(More)
BACKGROUND Spontaneous supratentorial intracerebral haemorrhage accounts for 20% of all stroke-related sudden neurological deficits, has the highest morbidity and mortality of all stroke, and the role of surgery remains controversial. We undertook a prospective randomised trial to compare early surgery with initial conservative treatment for patients with(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 NO3-N and NH4-N were markedly higher(More)
Urbanization is increasing rapidly in semi-arid environments and is predicted to alter atmospheric deposition of nutrients and pollutants to cities as well as to ecosystems downwind. We examined patterns of wet and coarse dry deposition chemistry over a five-year period at 7 sites across the Central Arizona-Phoenix (CAP) study area, one of two urban sites(More)
Urbanization represents the extreme case of human influence on an ecosystem. Biogeochemical cycling of nitrogen (N) in cities is very different from that of non-urban landscapes due to the large input of reactive forms of N and the heterogeneous distribution of various land uses that alters landscape connections. To quantify the likely effects of human(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)