Performance Assessment of Rain Gardens1

Abstract: The most widely used approach for evaluating the performance of stormwater best management practices (BMPs) such as rain gardens is monitoring, but this approach can involve a long time period to observe a sufficient number and variety of storm events, a high level of effort, and unavoidable uncertainty. In this paper, we describe the development and evaluation of three approaches for performance assessment of rain gardens: visual inspection, infiltration rate testing, and synthetic drawdown testing. Twelve rain gardens in Minnesota underwent visual inspection, with four determined to be nonfunctional based on one or more of the following criteria: (1) presence of ponded water, (2) presence of hydric soils, (3) presence of emergent (wetland) vegetation, and (4) failing vegetation. It is believed that these rain gardens failed due to a lack of maintenance. For the remaining eight rain gardens, an infiltrometer was used to determine the saturated hydraulic conductivity (K_sat) of the soil surface at several locations throughout each basin in what is termed infiltration rate testing. The median K_sat values for the rain gardens ranged from 3 to 72 cm/h. Synthetic drawdown testing was performed on three rain gardens by filling the basins with water to capacity where possible and recording water level over time. The observed drain times for two of those rain gardens were in good agreement with predictions based on the median of the infiltrometer measurements. The observed drain time for the third rain garden was much greater than predicted due to the presence of a restrictive soil layer beneath the topsoil. The assessment approaches developed in this research should prove useful for determining whether the construction of the rain garden was performed properly, a rain garden is functioning properly, and for developing maintenance tasks and schedules.     

Corticosterone levels in relation to migratory readiness in red-eyed vireos (<Emphasis Type="Italic">Vireo olivaceus</Emphasis>)

We examined the relationship between plasma levels of corticosterone and the migratory activity and directional preference of red-eyed vireos during fall migration at the northern coast of the Gulf of Mexico. Corticosterone is thought to play a role in physiological and behavioural processes before, during, and after long-distance migratory flights. An increase in corticosterone at the onset of migratory flights can be expected in birds that are energetically prepared to migrate in a seasonally appropriate southerly direction. Red-eyed vireos ( Vireo olivaceus) were tested in orientation cages under clear twilight skies. Just prior to the orientation experiments, blood was sampled to assay baseline corticosterone levels. Average corticosterone level for all birds was 22.8 ng/ml. Red-eyed vireos with higher than average baseline levels of corticosterone were significantly more active in orientation cages compared to birds with lower levels of corticosterone. Moreover, birds with higher than average levels oriented in a southwesterly direction, which is consistent with a trans-Gulf flight, whereas individuals with levels below average showed a NNW mean direction. Although there was no significant difference in baseline levels of corticosterone between fat and lean birds, individual mass loss between capture and test was negatively correlated with corticosterone levels. Results from this study clearly demonstrate that corticosterone influences departure decisions and the choice of direction during migration.     

Studying citizen science through adaptive management and learning feedbacks as mechanisms for improving conservation

Citizen science has generated a growing interest among scientists and community groups, and citizen science programs have been created specifically for conservation. We examined collaborative science, a highly interactive form of citizen science, which we developed within a theoretically informed framework. In this essay, we focused on 2 aspects of our framework: social learning and adaptive management. Social learning, in contrast to individual‐based learning, stresses collaborative and generative insight making and is well‐suited for adaptive management. Adaptive‐management integrates feedback loops that are informed by what is learned and is guided by iterative decision making. Participants engaged in citizen science are able to add to what they are learning through primary data collection, which can result in the real‐time information that is often necessary for conservation. Our work is particularly timely because research publications consistently report a lack of established frameworks and evaluation plans to address the extent of conservation outcomes in citizen science. To illustrate how our framework supports conservation through citizen science, we examined how 2 programs enacted our collaborative science framework. Further, we inspected preliminary conservation outcomes of our case‐study programs. These programs, despite their recent implementation, are demonstrating promise with regard to positive conservation outcomes. To date, they are independently earning funds to support research, earning buy‐in from local partners to engage in experimentation, and, in the absence of leading scientists, are collecting data to test ideas. We argue that this success is due to citizen scientists being organized around local issues and engaging in iterative, collaborative, and adaptive learning.     

Transitioning from unstable to stable colony growth in the desert leafcutter ant Acromyrmex versicolor

Like organisms, cohesive social groups such as insect colonies grow from a few individuals to large and complex integrated systems. Growth is driven by the interplay between intrinsic growth rates and environmental factors, particularly nutritional input. Ecologically inspired population growth models assume that this relationship remains constant until maturity, but more recent models suggest that it should be less stable at small colony sizes. To test this empirically, we monitored worker population growth and fungal development in the desert leafcutter ant, Acromyrmex versicolor, over the first 6 months of colony development. As a multitrophic, symbiotic system, leafcutter colonies must balance efforts to manage both fungus production and the growth of the ants consuming it. Both ants and fungus populations grew exponentially, but the shape of this relationship transitioned at a size threshold of 89?±?9 workers. Above this size, colony mortality plummeted and colonies shifted from hypometric to hypermetric growth, with a distinct stabilization of the relationship between the worker population and fungus. Our findings suggest that developing colonies undergo key changes in organizational structure and stability as they grow, with a resulting positive transition in efficiency and robustness.     

The challenge of biased evidence in conservation

Efforts to tackle the current biodiversity crisis need to be as efficient and effective as possible given chronic underfunding. To inform decision-makers of the most effective conservation actions, it is important to identify biases and gaps in the conservation literature to prioritize future evidence generation. We used the Conservation Evidence database to assess the state of the global literature that tests conservation actions for amphibians and birds. For the studies in the database, we investigated their spatial and taxonomic extent and distribution across biomes, effectiveness metrics, and study designs. Studies were heavily concentrated in Western Europe and North America for birds and particularly for amphibians, and temperate forest and grassland biomes were highly represented relative to their percentage of land coverage. Studies that used the most reliable study designs—before-after control-impact and randomized controlled trials—were the most geographically restricted and scarce in the evidence base. There were negative spatial relationships between the numbers of studies and the numbers of threatened and data-deficient species worldwide. Taxonomic biases and gaps were apparent for amphibians and birds—some entire orders were absent from the evidence base—whereas others were poorly represented relative to the proportion of threatened species they contained. Metrics used to evaluate effectiveness of conservation actions were often inconsistent between studies, potentially making them less directly comparable and evidence synthesis more difficult. Testing conservation actions on threatened species outside Western Europe, North America, and Australasia should be prioritized. Standardizing metrics and improving the rigor of study designs used to test conservation actions would also improve the quality of the evidence base for synthesis and decision-making.     

THE POLITICAL ECONOMY OF AGRICULTURE,GROUND WATER QUALITY MANAGEMENT,AND AGRICULTURAL RESEARCH1

ABSTRACT: The growing problem of nonpoint source ground water contamination from agricultural chemicals is conceptualized as an historical outcome of the production environment of capitalist agriculture in the Corn Belt. Chronic overproduction and ground water contamination reveal different aspects of the same technological treadmill. The debate over Iowa's 1987 Ground Water Protection Act symbolizes the contradiction between popular demand for clean water and structural limits on policymaking. Although the Act does provide for expanded research, education, and monitoring, a coalition of commercial farmers, local chemical dealers, and the national chemical industry defeated a tax on pesticide use. Analysis of alternate policy responses - Best Management Practices (BMPs), cross compliance, site-specific regulation of chemical use, and taxation of synthetic chemicals - reveals that all tend to founder on the same structural constraints. Without practical, profitable, low-input technologies that farmers, over time, would choose to adopt, both voluntary and regulatory approaches encounter major political or implementation difficulties. The public agricultural research agenda, therefore, emerges as a central control variable for ground water quality management and a central focus for political struggle.     

Comparison and analysis of different approaches for estimating the human exposure to phthalate esters

The human exposure estimates for dibutyl (DBP) and bis(2-ethylhexyl) phthalate (DEHP) made by two models EUSES and ACC-Human, and by an estimation approach which utilized measured concentrations in exposure media, were compared. The approach which utilized the latest monitoring data for important exposure media, yielded median daily intakes for adult humans for DBP and DEHP of 2.7 and 5.6 microg/kg body weight per day, respectively, which were in the same range as previous estimates based on back-calculation from urinary metabolites. EUSES estimated average daily intakes of DBP and DEHP for humans that were between 8 and 13 times lower. ACC-Human does not estimate average daily intakes, but ACC-Human-estimated human milk concentrations/fugacities were more than a thousand times lower than measured concentrations/fugacities in human milk. It was concluded that the two models underestimate human exposure to phthalate esters because they consider only a few key pathways that are known to be important for other, more persistent, hydrophobic organic compounds. Further, it was shown that there are differences between the two models on the methodology for estimating concentrations in exposure media such as vegetation, milk, beef and fish. ACC-Human uses a mechanistic approach for estimating transfer through aquatic and terrestrial food chains that are known to be important for human exposure to persistent, hydrophobic organics and can, unlike EUSES, account for food chain metabolism. It proved difficult, however, to obtain organism metabolism rates needed as model inputs to ACC-Human. If exposure estimates of phthalate esters are needed, it is recommended to use an estimation approach based on high quality monitoring data as presented here and/or back-calculate daily intake from concentrations of metabolites in human urine samples from the general population.     

An ethical analysis of hydrometeorological prediction and decision making: The case of the 1997 Red River flood

Weather, climate, and flood predictions are incorporated into human decisions in a wide variety of situations, including decisions related to hazardous hydrometeorological events. This article examines ethical aspects of such predictions and decisions, focusing on the case of the 1997 Red River flood in Grand Forks, North Dakota and East Grand Forks, Minnesota (US). The analysis employs a formal ethical framework and analytical method derived from medical and business ethics. The results of the analysis highlight issues related to forecast generation, communication of forecast meaning and uncertainty, responsibility for the use of forecasts in decision making, and trade-offs between the desire for forecast certainty and the risk of missed events. Implications of the analysis for the broader arenas of weather, climate, and flood prediction and disaster management are also discussed.