No abstract

We investigated geographic patterns of herbivory and resource allocation to defense, growth, and reproduction in an invasive biennial, Alliaria petiolata, to test the hypothesis that escape from herbivory in invasive species permits enhanced growth and lower production of defensive chemicals. We quantified herbivore damage, concentrations of sinigrin, and growth and reproduction inside and outside herbivore exclusion treatments, in field populations in the native and invasive ranges. As predicted, unmanipulated plants in the native range (Hungary, Europe) experienced greater herbivore damage than plants in the introduced range (Massachusetts and Connecticut, USA), providing evidence for enemy release, particularly in the first year of growth. Nevertheless, European populations had consistently larger individuals than US populations (rosettes were, for example, eightfold larger) and also had greater reproductive output, but US plants produced larger seeds at a given plant height. Moreover, flowering plants showed significant differences in concentrations of sinigrin in the invasive versus native range, although the direction of the difference was variable, suggesting the influence of environmental effects. Overall, we observed less herbivory, but not increased growth or decreased defense in the invasive range. Geographical differences in performance and leaf chemistry appear to be due to variation in the environment, which could have masked evolved differences in allocation.

The success of long-term sustainable biofuel production on agricultural lands is still questionable. To this end, we investigated the effects of crop prices on the changes of agricultural land use for biofuel canola production in three wheat crop management zones in North Dakota. The effects of canola hydroprocessed esters and fatty acids (HEFA) production on greenhouse gas (GHG) emissions and energy demand were investigated along with different allocation methods. The Environmental Policy Integrated Climate (EPIC) and Alternative Fuel Transportation Optimization Tool (AFTOT) models were used to simulate the life cycle assessment (LCA) inputs for two key stages of the HEFA pathway: cultivation and transportation. From the EPIC model results, the increase in canola price had a significant impact on predicted farmer decisions to displace food crops with energy crops and particularly on resulting changes in soil carbon (C). The LCA results suggested that to increase soil C sequestration, energy canola should be grown in the place of the fallow whenever possible to guarantee the long-term soil C sustainability of canola HEFA. Other possible ways to mitigate the GHG emissions included using anhydrous ammonia as the nitrogen fertilizer for cultivation and H2 integration (use of HEFA coproducts in H2 production) for HEFA conversion.

to describe the steps involved in bringing plant-based feedstocks to market for aviation biofuels production. A candidate feedstock is assigned a FSRL level from 1 through 9, indicating an increasing level of maturity towards commercialization. The FSRL level also communicates the state of development of a feedstock concurrent with its readiness for use with a conversion process. There are four components to the FSRL (production, market, policy, and linkage to conversion process), each with one to four tollgate descriptions per readiness level. The FSRL tool was structured to complement the Fuel Readiness Level (FRL) tool in use by the aviation industry as an internationally recognized communication best practice. Similarly, the FSRL can be used to identify gaps in any feedstock supply chain designed for any biofuel or conversion process that provides a market for feedstocks. This integrated feedstock and conversion technology approach can facilitate a coordinated allocation of resources to effectively plan for and develop a viable aviation biofuels industry.

No abstract

To evaluate the relationship between aircraft noise exposure and the quality of national park visitor experience, more than 4600 visitor surveys were collected at seven backcountry sites in four U.S. national parks simultaneously with calibrated sound level measurements. Multilevel logistic regression was used to estimate parameters describing the relationship among visitor responses, aircraft noise dose metrics, and mediator variables. For the regression models, survey responses were converted to three dichotomous variables, representing visitors who did or did not experience slightly or more, moderately or more, or very or more annoyance or interference with natural quiet from aircraft noise. Models with the most predictive power included noise dose metrics of sound exposure level, percent time aircraft were audible, and percentage energy due to helicopters and fixed-wing propeller aircraft. These models also included mediator variables: visitor ratings of the "importance of calmness, peace and tranquility," visitor group composition (adults or both adults and children), first visit to the site, previously taken an air tour, and participation in bird-watching or interpretive talks. The results complement and extend previous research conducted in frontcountry areas and will inform evaluations of air tour noise effects on visitors to national parks and remote wilderness sites.

Abstract. Biofuels are being pursued for their potential greenhouse gas (GHG) emissions benefits, among other reasons. In order to maximize productivity, avoid food-fuel conflicts, and minimize GHG emissions, many advanced biofuel feedstock crops, such as those desired by the aviation community, are under consideration based on traits, such as high biomass and/ or seed production, tolerance of marginal cultivation conditions, and short generation times, that may also be predictors of potential invasiveness risk. Biofuel-related invasion risks can be mitigated through careful feedstock crop selection and cultivation techniques developed from the invasion science literature. Existing voluntary best practices and some state and federal regulatory requirements in the United States recommend and/or require the use of such risk mitigation strategies. However, other policies and programs allow or provide incentives for biofuel production without conditions requiring the use of these strategies. We have synthesized information on the scientific knowledge of invasive species predictors and their use (or absence) in voluntary codes and U.S. regulatory frameworks and incentive programs. We highlight the existing tools and approaches for assessing invasion risk and avoiding the introduction and spread of invasive species as a result of biofuel feedstock cultivation. A wellcoordinated combination of species restrictions, biosecurity requirements, and incentives for selection of less risky biofuel crops may effectively balance the desire for increased biofuel production while minimizing invasion risk.

The aviation sector's commitments to carbon‐neutral growth in international aviation starting in 2020, and the desire to improve supply surety, price stability, and the environmental performance of aviation fuels, have led to broad interest in sustainable alternative jet fuels. Here, we use the system‐dynamics‐based biomass scenario model (BSM), focused on alternative jet fuel production capacity evolution, and the geospatially explicit Freight and Fuel Transportation Optimization Tool (FTOT), focused on optimal feedstock and fuel flows over the transportation system, to explore the incentive effects on alternative jet fuel production capacity trajectories and potential geospatial patterns of production and delivery in the USA. Scenarios presented here focus on readily available waste feedstocks (waste fats, oils and greases, municipal solid waste, and crop and forestry residues) and conversion technologies included in the ASTM D7566 synthesized aviation turbine fuels specification. The BSM modeling of possible deployment trajectories from 2015 to 2045 suggests that up to 8 billion gallons may be available by 2045 depending on the policies and incentives implemented. Both approaches suggest that 200 million to 1 billion gallons per year of alternative jet fuel production are possible in 2030 given multiple incentives and a favorable investment climate, and that capital costs and technology maturation rates will affect deployment of different fuel production technologies, and therefore the feedstocks needed. Further collaboration on these modeling approaches would reduce methodological blind spots while providing insights into future industry trajectories. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd