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The rank-abundance distribution (RAD) represents the manner in which species divide resources. Community-specific division rules that determine resource allocation among species, and thereby the shape of the RAD, have been hypothesized to account for observed stability of local species richness over time. While the shape of the RAD has been well studied, the temporal dynamics of this distribution have received much less attention. Here we assess changes in the shape of the RAD through time in a desert rodent community in Arizona (USA). Because energy use may be more appropriate for studying resource division than abundance, we also evaluate an energetic equivalent of the RAD. Significant, directional trends in the shapes of both distributions are present in this community. These changes are driven by trends in the relative abundances (or energy use) of Ranks 2, 3, and 4, and are significantly correlated with variation in total energy use by the community and with compositional change. Our results suggest that (1) rank-abundance and rank-energy distributions are not static and can change directionally through time, (2) species richness and rank distributions are not necessarily as intimately connected as early studies assumed, and (3) rank-abundance and rank-energy distributions are influenced by both the amount of energy available to the community and species-specific interactions. [ABSTRACT FROM AUTHOR]

The article discusses various environmental successes along the U.S./Mexico border in the Arizona/Sonora border region, such as the cooperation between the U.S., Mexico, and environmental organizations to allocate water from the Colorado River to protect the Cienega de Santa Clara in Sonora, Mexico. The authors note that environmental accomplishments result from a strong network between individuals, known as a "network weavers," who are motivated by a love of place. The focus of the article is a study of network members who are dedicated to the conservation and cultural preservation of the Arizona/Sonora border. Topics include an overview of the Arizona/Sonora region and the importance of social networks to successful environmental protection.

Climate is a potential driver of tree allometry. To explore the sensitivity of height-diameter allometry to climate change, we compiled height-diameter pairs of ponderosa pine (Pinus ponderosa) in Arizona, western United States, together with the climate and environmental data of this species' growing sites into a dataset, and selected power-law function as the basic allometric model. Then, the scaling parameters of basic model were re-parameterized to incorporate climate and environmental variables, and ordinary least squares and nonlinear mixed-effects (NLME) methods were used to fit and predict, respectively. The results showed that the NLME height-diameter allometric model performed best in this study. Tree height was positively affected by precipitation and competition from neighbors, while it was negatively affected by the elevation of tree living site. The relative importance analysis showed that competition-related variables were the most important environmental factors that had shaped height-diameter allometric relationship of ponderosa pine. In general, the height-diameter allometry of ponderosa pine was dominated by mechanical constraints, but the allometric variation was mainly caused by the differences of environment. Our results not only help to understand the response mechanism of tree resource allocation to environmental gradients but also contribute to forest management decision-making under future climate changes. [ABSTRACT FROM AUTHOR]

Two critical concerns with the rapid and ongoing expansion of charter schools are that they will segregate students and reduce the per-pupil resources available to conventional public schools. The contradictory prior evidence on such questions is based on potentially misleading cross-sectional comparisons. This study provides new evidence on these issues by conducting panel-based evaluations using school-level data from Arizona and neighboring states. These results suggest that the introduction of charter schools in Arizona has increased pupil–teacher ratios in traditional public schools by 6 percent and reduced the proportion of white non-Hispanic students by 2 percent. [Copyright &y& Elsevier]

This article presents the results of the exploratory study examining how counties in Arizona use the common pool resource of prison space. The author remarks that over time, society appears to have largely abandoned the wide range of punishments that were once available and adopted the perception that there is only one true corrective penalty for criminal behavior, prison. Although criminal justice resource allocation decisions are implied in each of these movements, they are rarely directly addressed or evaluated. Prison space represents an important public good with a finite capacity that may, at times, be expanded to meet exigent needs. In this article, the authors examine to what extent the use of prison space mirrors the tragedy of the commons found in more traditional resource management literature. Conversely, we also investigate the plausibility that the use of prison space actually reflects the needs, crime rates, and criminal justice expenditures of the local jurisdictions sending inmates into the state prison system.

Objectives. We examined the costs of treating American Indian adults with diabetes within the Indian Health Service (IHS). Methods. We extracted demographic and health service utilization data from the IHS electronic medical reporting system for 32052 American Indian adults in central Arizona in 2004 and 2005. We derived treatment cost estimates from an IHS facility-specific cost report. We examined chronic condition prevalence, medical service utilization, and treatment costs for American Indians with and without diabetes. Results. IHS treatment costs for the 10.9% of American Indian adults with diabetes accounted for 37.0% of all adult treatment costs. Persons with diabetes accounted for nearly half of all hospital days (excluding days for obstetrical care). Hospital inpatient service costs for those with diabetes accounted for 32.2% of all costs. Conclusions. In this first study of treatment costs within the IHS, costs for American Indians with diabetes were found to consume a significant proportion of IHS resources. The findings give federal agencies and tribes critical information for resource allocation and policy formulation to reduce and eventually eliminate diabetes-related disparities between American Indians and Alaska Natives and other racial/ethnic populations. [ABSTRACT FROM AUTHOR]

This Note explores a battle for water in the Southwest that may ultimately destroy one of Arizona's most precious rivers. This struggle pits the doctrine of reasonable use against the doctrine of prior appropriation and exposes the need to reconcile the uniquely Arizonan concept of "subflow, "which purports to synthesize the laws of ground and surface water, with scientific reality. The characters in this complicated battle include rural municipalities that plan to pump from the river, headwaters, a major metropolitan utility company with century-old rights to the river, and an environmental advocacy organization seeking to protect endangered species. The plight of the Verde River exemplifies what has become a common tale in the United States-multiple parties with valid rights to the same water under different laws. Its resolution will likely require some difficult decisions about resource allocation, rural and urban growth, and the courts' willingness to side with science in the face of impossibly high stakes and a river in peril. [ABSTRACT FROM AUTHOR]

Pollinator attraction, pollen limitation, resource limitation, pollen donation and selective fruit abortion have all been proposed as processes explaining why hermaphroditic plants commonly produce many more flowers than mature fruit. We conducted a series of experiments in Arizona to investigate low fruit-to-flower ratios in senita cacti, which rely exclusively on pollinating seed-consumers. Selective abortion of fruit based on seed predators is of particular interest in this case because plants relying on pollinating seed-consumers are predicted to have such a mechanism to minimize seed loss. Pollinator attraction and pollen dispersal increased with flower number, but fruit set did not, refuting the hypothesis that excess flowers increase fruit set by attracting more pollinators. Fruit set of natural- and hand-pollinated flowers were not different, supporting the resource, rather than pollen, limitation hypothesis. Senita did abort fruit, but not selectively based on pollen quantity, pollen donors, or seed predators. Collectively, these results are consistent with sex allocation theory in that resource allocation to excess flower production can increase pollen dispersal and the male fitness function of flowers, but consequently results in reduced resources available for fruit set. Inconsistent with sex allocation theory, however, fruit production and the female fitness function of flowers may actually increase with flower production. This is because excess flower production lowers pollinator-to-flower ratios and results in fruit abortion, both of which limit the abundance and hence oviposition rates, of pre-dispersal seed predators. [ABSTRACT FROM AUTHOR]

The water footprint provided a full methodology to operationalise the virtual water concept (the volume of water used along a supply chain to produce products and services). A key theme in the water footprint literature is the efficient allocation of water resources at the global scale given the feasibility of trading water intensive commodities from water rich to water poor areas: this is an economic problem of resource allocation between alternative and competing demands, albeit with a novel international component. Moreover, given that price signals indicating relative scarcity are usually either absent or distorted for water, it is also a problem that can be seen through the lens of environmental (or non-market) valuation. However, to date environmental valuation has not been used to inform the efficient use and allocation of water within and between the different locations encompassed by international supply chains. Drawing on an agri-food supply chain framework that we propose in this paper, we begin by conceptualising the economic values that accrue to water consumption (blue and green water) and degradation (grey water) at different points along a supply chain. Based on this conceptualisation, we assess the extent to which it is possible to approximate these economic values by relying on existing secondary data on the shadow value of water in different contexts. The use of secondary data in this way is known as benefit (or value) transfer. To achieve this, 706 unit estimates of the economic value of water are collected, standardised and reviewed encompassing off-stream water applications (agriculture, industry and municipal) and in-stream ecosystem services (waste assimilation, wildlife habitat, recreation, hydrological functions and passive uses). From this, a proposed methodology for valuing virtual water is presented and illustrated using the case study of global durum wheat pasta production. The case study shows the total value of the virtual water used to produce one tonne of durum wheat pasta ($212). More importantly, the case study also highlights how variations in economic value between multiple locations where durum wheat is cultivated (Saskatchewan $0.10 m3, Arizona $0.08 m3 and Baja California $0.24 m3) indicate relative water scarcity and thus impact, as well as the potential for a more efficient allocation of virtual water. The main conclusion from this research is that when geographical disparities in the economic value of water use within a supply chain are accounted for, what was perhaps considered sustainable in volume terms, might not, in fact, represent the optimal allocation. However, future research opportunities highlight the need for additional data collection on the economic value of water in several contexts. This additional data would help the environmental valuation community to undertake a more comprehensive and robust approach to virtual water valuation. This paper is accompanied by the Data in Brief article entitled "Dataset on the in-stream and off-stream economic value of water." Image 1 • We review estimates of the economic value of water. • We propose a new framework and methodology for estimating the economic value of virtual water. • Geographical disparities in economic value should inform sustainable sourcing and supply chain management. • There is a need for more data on the economic value of water in several categories. [ABSTRACT FROM AUTHOR]