Soil, Vegetation, and Seed Bank of a Sonoran Desert Ecosystem Along an Exotic Plant (Pennisetum ciliare) Treatment Gradient

Ecological conditions following removal of exotic plants are a key part of comprehensive environmental management strategies to combat exotic plant invasions. We examined ecological conditions following removal of the management-priority buffelgrass (Pennisetum ciliare) in Saguaro National Park of the North American Sonoran Desert. We assessed soil, vegetation, and soil seed banks on seven buffelgrass site types: five different frequencies of buffelgrass herbicide plus hand removal treatments (ranging from 5 years of annual treatment to a single year of treatment), untreated sites, and non-invaded sites, with three replicates for each of the seven site types. The 22 measured soil properties (e.g., pH) differed little among sites. Regarding vegetation, buffelgrass cover was low (≤1 % median cover), or absent, across all treated sites but was high (10–70 %) in untreated sites. Native vegetation cover, diversity, and composition were indistinguishable across site types. Species composition was dominated by native species (>93 % relative cover) across all sites except untreated buffelgrass sites. Most (38 species, 93 %) of the 41 species detected in soil seed banks were native, and native seed density did not differ significantly across sites. Results suggest that: (1) buffelgrass cover was minimal across treated sites; (2) aside from high buffelgrass cover in untreated sites, ecological conditions were largely indistinguishable across sites; (3) soil seed banks harbored ≥12 species that were frequent in the aboveground vegetation; and (4) native species dominated post-treatment vegetation composition, and removing buffelgrass did not result in replacement by other exotic species.     

Rarefaction and nonrandom spatial dispersion patterns

Rarefaction estimates how many species are expected in a random sample of individuals from a larger collection and allows meaningful comparisons among collections of different sizes. It assumes random spatial dispersion. However, two common dispersion patterns, within-species clumping and segregation among species, can cause rarefaction to overestimate the species richness of a smaller continuous area. We use field studies and computer simulations to determine (1) how robust rarefaction is to nonrandom spatial dispersion and (2) whether simple measures of spatial autocorrelation can predict the bias in rarefaction estimates. Rarefaction does not estimate species richness accurately for many communities, especially at small sample sizes. Measures of spatial autocorrelation of the more abundant species do not reliably predict amount of bias. Survey sites should be standardized to equal-sized areas before sampling. When sites are of equal area but differ in number of individuals sampled, rarefaction can standardize collections. When communities are sampled from different-sized areas, the mean and confidence intervals of species accumulation curves allow more meaningful comparisons among sites. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

Incentive compatibility tests of choice experiment value elicitation questions

This paper uses laboratory experiments with induced values to address fundamental issues related to the incentive compatibility of choice experiment value elicitation questions. In particular, we compare two- versus three-option choice sets and the effect of using alternative provision rules, including one where the outcome is influenced by both participant and “regulator” votes. We find the overall proportion of choices that are inconsistent with induced preferences is rather low. However, there are more deviations from induced preferences for two-option choice sets, and for alternatives to a simple plurality vote implementation rule. A multinomial probit analysis of choices in tandem with a mixed logit welfare analysis suggests there is a statistically significant but modest degree of bias towards selecting the status quo option.     

Incorporation of Seasonal Nitrogen Dynamics within a Long-Term Acidification Model

This paper describes an application of the long termdynamic model, MAGIC, on a monthly timestep, enablingincorporation of the seasonal dynamics associated with abroad understanding of the ecosystem N cycle. The modelhas been applied to the Dargall Lane catchment in theGalloway region of Scotland where marked seasonal Ndynamics are apparent. Mean monthly proportions ofrainfall, runoff, deposition fluxes and net retention ofN are utilised to drive the model on a monthly timestep.Calibration of the model has successfully reproduced thepresent day observed seasonal variation in streamNO₃ and ANC. Prediction of recovery at the siteunder the second sulphur protocol indicates that,although mean annual ANC increases, mean monthly ANC doesnot rise above zero for all months of the year until2010.     

Hurricane Harvey and Greater Houston households: comparing pre-event preparedness with post-event health effects,event exposures,and recovery

Most disaster studies rely on convenience sampling and ‘after-only’ designs to assess impacts. This paper, focusing on Hurricane Harvey (2017) and leveraging a pre-/post-event sample of Greater Houston households (n=71) in the United States, establishes baselines for disaster preparedness and home structure flood hazard mitigation, explores household-level ramifications, and examines how preparedness and mitigation relate to health effects, event exposures, and recovery. Between 70 and 80 per cent of participants instituted preparedness measures. Mitigation actions varied: six per cent had interior drainage systems and 83 per cent had elevated indoor heating/cooling components. Sixty per cent reported home damage. One-half highlighted allergies and two-thirds indicated some level of post-traumatic stress (PTS). Three-quarters worried about family members/friends. The results of generalised linear models revealed that greater pre- event mitigation was associated with fewer physical health problems and adverse experiences, lower PTS, and faster recovery. The study design exposed the broad benefits of home structure flood hazard mitigation for households after Harvey.     

Research priorities for managing the impacts and dependencies of business upon food,energy, water and the environment

Delivering access to sufficient food, energy and water resources to ensure human wellbeing is a major concern for governments worldwide. However, it is crucial to account for the ‘nexus’ of interactions between these natural resources and the consequent implications for human wellbeing. The private sector has a critical role in driving positive change towards more sustainable nexus management and could reap considerable benefits from collaboration with researchers to devise solutions to some of the foremost sustainability challenges of today. Yet opportunities are missed because the private sector is rarely involved in the formulation of deliverable research priorities. We convened senior research scientists and influential business leaders to collaboratively identify the top forty questions that, if answered, would best help companies understand and manage their food-energy-water-environment nexus dependencies and impacts. Codification of the top order nexus themes highlighted research priorities around development of pragmatic yet credible tools that allow businesses to incorporate nexus interactions into their decision-making; demonstration of the business case for more sustainable nexus management; identification of the most effective levers for behaviour change; and understanding incentives or circumstances that allow individuals and businesses to take a leadership stance. Greater investment in the complex but productive relations between the private sector and research community will create deeper and more meaningful collaboration and cooperation.     

Adaptation policy and community discourse: risk,vulnerability, and just transformation

How can public engagement assist in the development of just processes and outcomes in adaptation discourse and policymaking? A concern with justice is at the center of thinking about adaptation that is not only resilient, but also public, engaging, and transformative. Theoretically, the intersection of adaptation, transformation, and environmental and climate justice is examined, before exploring the specific concerns and normative foundations for adaptation policy articulated by local governments, environmental groups, and local residents engaged in adaptation planning in Australia. Despite a discursive disconnect between governmental focus on a risk or resilience-based approach and a community concern with the vulnerability of basic needs and capabilities of everyday life, deliberative engagement in adaptation planning can both address issues of justice and represent a transformative practice.     

Presenting Triple-Wins? Assessing Projects That Deliver Adaptation,Mitigation and Development Co-benefits in Rural Sub-Saharan Africa

The concept of climate compatible development (CCD) is increasingly employed by donors and policy makers seeking ‘triple-wins’ for development, adaptation and mitigation. While CCD rhetoric is becoming more widespread, analyses drawing on empirical cases that present triple-wins are sorely lacking. We address this knowledge gap. Drawing on examples in rural sub-Saharan Africa, we provide the first glimpse into how projects that demonstrate triple-win potential are framed and presented within the scientific literature. We identify that development projects are still commonly evaluated in terms of adaptation or mitigation benefits. Few are framed according to their benefits across all three dimensions. Consequently, where triple-wins are occurring, they are likely to be under-reported. This has important implications, which underestimates the co-benefits that projects can deliver. A more robust academic evidence base for the delivery of triple-wins is necessary to encourage continued donor investment in activities offering the potential to deliver CCD.     

Pyrethroid pesticide effects on behavioral responses of aquatic isopods to danger cues

The present study sought to evaluate the behavioral responses of non-target organisms in order to determine whether phototactic responses of isopods to danger cues are altered as a function of exposure to the pyrethroid pesticides λ-cyhalothrin and bifenthrin. Experiments conducted on Gnorimosphaeroma oregonensis identified sublethal behavioral responses to pyrethroids, λ-cyhalothrin and bifenthrin at concentrations 0.15 ng/mL, 0.025 ng/mL, and 0.005 ng/mL. Experimental setup tested isopod phototactic responses across six treatments: control, pyrethroid, hemolymph, predator, hemolymph?+?pyrethroid, and predator?+?pyrethroid. Isopods exhibited no preference for phototactic responses in the control and pyrethroid treatments. When exposed to danger cues (hemolymph or predator), isopods exhibited significant negative phototaxis, as expected. When exposure to danger cues was combined with pyrethroids, isopods again exhibited no preference for phototactic response. Experiments indicate that pyrethroids diminish isopod’s negatively phototactic response to danger cues.     

Use of Calluna vulgaris to detect signals of nitrogen deposition across an urban–rural gradient

Densely populated cities can experience high concentrations of traffic-derived pollutants, with oxides of nitrogen and ammonia contributing significantly to the overall nitrogen (N) budget of urban ecosystems. This study investigated changes in the biochemistry of in situ Calluna vulgaris plants to detect signals of N deposition across an urban–rural gradient from central London to rural Surrey, UK. Foliar N concentrations and δ¹⁵N signatures were higher, and C/N ratios lower, in urban areas receiving the highest rates of N deposition. Plant phosphorus (P) concentrations were also highest in these areas, suggesting that elevated rates of N deposition are unlikely to result in progressive P-limitation in urban habitats. Free amino acid concentrations were positively related to N deposition for asparagine, glutamine, glycine, phenylalanine, isoleucine, leucine and lysine. Overall, relationships between tissue chemistry and N deposition were similar for oxidised, reduced and total N, although the strength of relationships varied with the different biochemical indicators. The results of this study indicate that current rates of N deposition are having substantial effects on plant biochemistry in urban areas, with likely implications for the biodiversity and functioning of urban ecosystems.