Can initial intraspecific spatial aggregation increase multi-year coexistence by creating temporal priority?

Both intraspecific spatial aggregation and temporal priority effects have the potential to increase long-term species coexistence. Theory and models suggest that intraspecific aggregation can facilitate coexistence via limited dispersal or asymmetric interaction distances. During community assembly, intraspecific aggregation may also delay interactions between more and less competitive species, thus creating opportunities for priority effects to facilitate longer-term coexistence. Few empirical studies have tested predictions about aggregation and coexistence, especially in the context of community assembly or ecological restoration. We investigated (1) impacts of intraspecific aggregation on the assembly of eight-species communities over three years, (2) the scale dependence of these impacts, and (3) implications for California prairie restoration. We planted eight native species in each of 19, 5 m wide, octagonal plots. Species were either interspersed throughout the plot or aggregated into eight, 2.2-m(2), wedge-shaped, monospecific sectors. Over three years, species diversity declined more quickly in interspersed plots than in aggregated plots. Two species had higher cover or increased more in interspersed than aggregated plots and were identified as "aggressives." Four species had higher cover or increased more in aggregated than interspersed plots and were identified as "subordinates." Within aggregated plots, aggressive species expanded beyond the sector in which they were originally seeded. Cover of aggressive species increased faster and reached higher values in sectors that were adjacent to the originally planted sector, compared to nonadjacent sectors. Cover of aggressive species also increased more and faster near plot centers, compared to plot edges. Areas near plot centers were representative of smaller aggregation patches since species were planted closer to heterospecific neighbors. Two subordinate species maintained higher cover near plot edges than near plot centers. Moreover, two subordinate species maintained higher cover when seeded in sectors farther away from aggressive species. These results suggest that initial intraspecific aggregation can facilitate species coexistence for at least three years, and larger aggregation patches may be more effective than smaller ones in the face of dispersing dominants. The creation of temporal priority effects may represent an underappreciated pathway by which intraspecific aggregation can increase coexistence. Restorationists may be able to maintain more diverse communities by planting in a mosaic of monospecific patches.     

Kinship,nomadism, and humanitarian aid among Somalis in Ethiopia

This paper draws on extended ethnographic and health policy research in eastern Ethiopia to reconsider kinship and nomadism among Somalis, as both of these cultural features transform in the contexts of recurrent humanitarian crises and episodic relief operations. The emergence and importance of new patterns of travel and migration among Somalis in Ethiopia reveal significant changes in the configurations and enactments of Somali kinship, on which many Somalis' mobility depends. Conversely, an analysis of Somalis' dynamic sub‐clan groupings and geographically dispersed kinship networks also highlights emergent patterns of mobility and migration that enable access to training opportunities and employment with relief organisations, as well as to distributions of humanitarian aid. Based on these findings, this paper argues that kinship and nomadism—both long central to Somalis' identities in Ethiopia—remain interdependent, coevolved, and key to their resilience and livelihoods in the face of recurrent crises and intermittent humanitarian responses.     

Extending wipe sampling methodologies to elements other than lead

Wipe sampling is the USA regulatory protocol for determination of "dust lead loadings" in residential environments. Few studies have applied the wipe sampling method to metals other than lead (Pb) for the purpose of residential exposure assessments. This study was undertaken to develop and expand the wipe method for quantifying additional metal(loid)s including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), and antimony (Sb); and to provide information on typical background loadings for these metals in urban Canadian homes. A total of 932 wipe samples, 220 field blanks, and 220 duplicate wipes were collected from 222 homes located in three cities in Ontario, Canada using the ASTM 1728 standard. The wipes were digested using a modified version of the ASTM 1644 standard for Pb, which prescribes a hot nitric acid/hydrogen peroxide digestion. The key modification was the addition of hydrofluoric acid to improve recoveries of the target elements, and determination using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Generally, a large proportion of the results fell below the limits of detection (LOD) and quantification (LOQ). To distinguish "elevated" metal loadings from loadings characterized as "urban background", an upper background threshold for each element was derived using a normality (Q-Q) plot. LOQ was determined to be the appropriate minimum threshold based on quality assurance criteria. It is concluded that wipes are a useful sampling option to investigate multi-element loadings in residential environments.     

Sources and fate of Salmonella and fecal indicator bacteria in an urban creek

This research aimed to understand the sources and fate of Salmonella and fecal bacteria in urban surface waters. An urban creek (San Pedro Creek, California, USA) that had unusually high levels of Salmonella and fecal bacteria relative to other nearby waterbodies was chosen as a model field site. State of the art microbiological methods were used in concert with modeling to investigate Salmonella and fecal bacteria sources, and determine field-relevant dark inactivation and photoinactivation rates. Three along-creek surveys that spanned reaches adjacent to both urban and forested land covers were conducted to measure Salmonella, enterococci, Escherichia coli, and horse- and human-specific Bacteroidales. Salmonella were detected adjacent to and downstream of urban land cover, but not adjacent to forested land cover. No human or horse-specific Bacteroidales fecal markers were detected implicating other urban animal sources of bacteria. Two locations along the creek where Salmonella was consistently detected were sampled hourly for 25 hours and a mass-balance model was applied to determine field-relevant light and dark inactivation rates for Salmonella, enterococci, and E. coli. Sunlight inactivation did not appear to be important in modulating concentrations of Salmonella, but was important in modulating both enterococci and E. coli concentrations. Dark inactivation was important for all three organisms. This is the first study to quantitatively examine the fate of Salmonella within an urban surface water. Although the work is carried out at a single site, the methodologies are extendable to source tracking in other waterbodies. Additionally, the rate constants determined through the modeling will be useful for modeling these organisms in other surface waters, and represent useful benchmarks for comparison to laboratory-derived inactivation rates.     

Benefits and Challenges of Linking Green Infrastructure and Highway Planning in the United States

Landscape-level green infrastructure creates a network of natural and semi-natural areas that protects and enhances ecosystem services, regenerative capacities, and ecological dynamism over long timeframes. It can also enhance quality of life and certain economic activity. Highways create a network for moving goods and services efficiently, enabling commerce, and improving mobility. A fundamentally profound conflict exists between transportation planning and green infrastructure planning because they both seek to create connected, functioning networks across the same landscapes and regions, but transportation networks, especially in the form of highways, fragment and disconnect green infrastructure networks. A key opportunity has emerged in the United States during the last ten years with the promotion of measures to link transportation and environmental concerns. In this article we examined the potential benefits and challenges of linking landscape-level green infrastructure planning and implementation with integrated transportation planning and highway project development in the United States policy context. This was done by establishing a conceptual model that identified logical flow lines from planning to implementation as well as the potential interconnectors between green infrastructure and highway infrastructure. We analyzed the relationship of these activities through literature review, policy analysis, and a case study of a suburban Maryland, USA landscape. We found that regionally developed and adopted green infrastructure plans can be instrumental in creating more responsive regional transportation plans and streamlining the project environmental review process while enabling better outcomes by enabling more targeted mitigation. In order for benefits to occur, however, landscape-scale green infrastructure assessments and plans must be in place before integrated transportation planning and highway project development occurs. It is in the transportation community’s interests to actively facilitate green infrastructure planning because it creates a more predictable environmental review context. On the other hand, for landscape-level green infrastructure, transportation planning and development is much more established and better funded and can provide a means of supporting green infrastructure planning and implementation, thereby enhancing conservation of ecological function.     

100 years running: The need to understand why employee physical activity benefits organizations

Employee physical activity initiatives are commonplace, but management scholarship has not kept pace with theoretical and empirical work to validate such initiatives. In this Incubator, we clarify the employee physical activity construct, present mechanisms linking physical activity to organizationally valued outcomes, and consider the dark side of employee physical activity initiatives. Copyright © 2015 John Wiley & Sons, Ltd.     

Comparing Contaminant Removal Costs for Aquifer Recharge with Wastewater with Water Supply Benefits

The use of waters of impaired quality has been suggested as a means to expand available water resources supply for water‐limited communities. An ongoing concern is the safety of supplies that use wastewater because of the potential for introduction of emerging contaminants such as pharmaceuticals into drinking water supplies. Prior research into contaminants of emerging concerns (CECs) have included a variety of methods, but the only consistent removal is with reverse osmosis (RO) membranes, ultraviolet light (UV), and advanced oxidation processes (AOP). However, few of these prior studies have measurable quantities of these contaminants in the influent wastewater, so determining actual removal percentages is difficult. This project was designed to evaluate the removal of CECs to verify that a 3‐log removal of common constituents was realized. Spike testing was used to compare to prior research and to evaluate whether the project costs were competitive with other forms of reuse or other water supplies. The combination of RO/UV/AOP was effective at obtaining a 3‐log removal of CECs, but the RO and UV/AOP processes alone were not capable of removing all substances. However, despite the extensive treatment, the proposed process was both competitive cost‐wise and met the water quality goals.