Intraspecific trait variation and reversals of trait strategies across key climate gradients in native Hawaiian plants and non-native invaders

Background and AimsDisplacement of native plant species by non-native invaders may result from differences in their carbon economy, yet little is known regarding how variation in leaf traits influences native–invader dynamics across climate gradients. In Hawaii, one of the most heavily invaded biodiversity hotspots in the world, strong spatial variation in climate results from the complex topography, which underlies variation in traits that probably drives shifts in species interactions.MethodsUsing one of the most comprehensive trait data sets for Hawaii to date (91 species and four islands), we determined the extent and sources of variation (climate, species and species origin) in leaf traits, and used mixed models to examine differences between natives and non-native invasives.Key ResultsWe detected significant differences in trait means, such that invasives were more resource acquisitive than natives over most of the climate gradients. However, we also detected trait convergence and a rank reversal (natives more resource acquisitive than invasives) in a sub-set of conditions. There was significant intraspecific trait variation (ITV) in leaf traits of natives and invasives, although invasives expressed significantly greater ITV than natives in water loss and photosynthesis. Species accounted for more trait variation than did climate for invasives, while the reverse was true for natives. Incorporating this climate-driven trait variation significantly improved the fit of models that compared natives and invasives. Lastly, in invasives, ITV was most strongly explained by spatial heterogeneity in moisture, whereas solar energy explains more ITV in natives.ConclusionsOur results indicate that trait expression and ITV vary significantly between natives and invasives, and that this is mediated by climate. These findings suggest that although natives and invasives are functionally similar at the regional scale, invader success at local scales is contingent on climate.     

Optimizing Circular Economy Planning and Risk Analysis Using System Dynamics

This article develops a systems dynamics and multi-objective programming model (SDMOP) for planning a regional circular economy. Various risk analyses are conducted using the technique of sensitivity analysis. This SDMOP model includes two modules: the MOP module used to derive optimized parameters as inputs to the systems dynamics model, and the systems dynamics module used to plan the regional circular economy. We demonstrate the application of this SDMOP model to a problem of planning the circular economy of a county in the Sichuan Province of China.     

How much sorting is required for a circular low carbon aluminum economy?

Aluminum recycling follows a downcycling dynamic where wrought alloys are transformed into cast alloys, accumulating tramp elements at every cycle. With the saturation of stocks of aluminum and the reduction of the demand for cast alloy due to electrification of transport, improvement in the recycling system must be made to avoid a surplus of unused recycled aluminum, reduce the overall environmental impacts of the industry, and move toward a circular economy. We aim to evaluate the potential environmental benefits of improving sorting efforts by combining operations research, prospective material flow analysis, and life cycle assessment. An optimization defines the optimal sorting to minimize climate change impacts according to different sorting efforts, dismantling conditions, and collection rates. Results show how the improvement of sorting can reduce by around 30% the greenhouse gas emissions of the industry, notably by reducing unused scrap generation and increasing the recycled content of the flows that supply the demand of aluminum. The best performance is achievable with four different sorting pathways. Further improvements occur with a better dismantling and an increase of collection rates, but it requires more sorting pathways. Results point to different closed-loop recycling initiatives that should be promoted on priority in specific sectors, like the building and construction sector and the aluminum cans industry. To implement a better material circularity, the mobilization of different stakeholders is needed. From a wider perspective, the article shows how operations research can be used to project a circular future in a specific industry. This article met the requirements for a Gold–Gold JIE data openness badge described at http://jie.click/badges .      

A forest beyond the trees: Tree cutting in rural Ghana

In this paper I examine the complexity of human forces involved in tree cutting in a Ghanaian forest region. I provide evidence to link the indiscriminate tree-cutting activities of some local communities to the gradual loss of communal control over land and the replacement of kin group control with state property regimes. I point to the interrelated factors of the state's promotion of an exportled development strategy, the intensification of agricultural commercialization, and household and group variations in access to land as all having deleterious impacts on local traditions of sustainable forestry.     

Living in a World of Smart Everyday Objects—Social,Economic, and Ethical Implications

Visions of Pervasive Computing and ambient intelligence involve integrating tiny microelectronic processors and sensors into everyday objects in order to make them “smart.” Smart things can explore their environment, communicate with other smart things, and interact with humans, therefore helping users to cope with their tasks in new, intuitive ways. Although many concepts have already been tested out as prototypes in field trials, the repercussions of such extensive integration of computer technology into our everyday lives are difficult to predict. This article is a first attempt to classify the social, economic, and ethical implications of this development.     

A framework to open the black box of the use phase in circular economy life cycle assessments: The case of shell jacket reuse

Life cycle assessments of circular economy measures (CE LCA) of consumer products have been criticized for oversimplifying important aspects of the use phase such as user behavior and rebound effects, limiting our understanding of the environmental performance of circular economy measures. This study tests the usefulness of a framework designed to facilitate accounting for such aspects, by applying the framework to a case study of reuse of shell jackets enabled by “premium secondhand” outdoor stores. Methods for collecting use phase data were user surveys and interviews with store managers. Using the framework on this case study generated several novel insights which are interesting in themselves and as inputs to CE LCA. For instance, secondhand shell jackets have a significantly lower frequency of use during their first use span compared to the second and to shell jackets in the linear reference scenario. This implies that reuse in this case does not function as a mere use extension of otherwise similar use phases as is commonly assumed. The generation of such insights, which hitherto have been lacking in CE LCAs, points to the usefulness of the framework as a tool for opening the “black box” of the use phase in CE LCAs to improve understanding of the environmental performance of circular economy measures.     

Can a small island nation build resilience? The significance of resource-use patterns and socio-metabolic risks in The Bahamas

Resource-use patterns may entail systemic risks and cascade effects, which consequently inhibit the ability to deliver socioeconomic services. Identifying resource-use patterns exhibiting systemic risks and reshaping their combinations is a potential lever in realizing the transition to a sustainable, resilient, and resource-secure system. Using an island context to assess the quantity and composition of resource throughput enables a more comprehensive analysis of these risks. This article presents the first mass-balance account of socio-metabolic flows for The Bahamas in 2018, to identify socio-metabolic risks and cascading effects. Socio-metabolic risks are systemic risks related to critical resource availability, material circulation integrity, and (in)equities in cost and benefit distributions. We utilize the economy-wide material flow accounting framework to map the material flow patterns across the economy. In 2018, annual direct material input was estimated at 9.4 t/cap/yr, of which 60% were imports. High masses of waste (1.4 t/cap/yr) remained unrecovered due to the lack of recycling. Total domestic extraction (DE) were dominated by non-metallic minerals with more than 80%, while marine biomass makes up barely 1% of total DE. Due to its linear, undiversified metabolism, and heavy imports dependency, the system is susceptible to socio-metabolic risks and cascading effects including low levels of self-sufficiency, high vulnerability to shocks, commodity price fluctuations, threats to sensitive ecosystems, health impacts, and economic losses, among others. A holistic resource management strategy and nature-based solutions that consider the trade-offs and synergies between different resource-use patterns are critical when exploring potential plans for metabolic risk reduction.     

Fisheries and the evolution of resource management on the lower Amazon floodplain

Traditionally, the ribeirinhoeconomy has been based on strategies of multiple resource use including agriculture, fishing, and small-scale stock raising. In the last two decades though, ribeirinhostrategies of resource management have undergone major changes due to the decline of jute production (the principal cash crop), and the intensification of the commercial fisheries. As a result of these trends, there has been a shift of ribeirinholabor from agriculture to commercial fishing. Today, the diversity which once characterized ribeirinhosubsistence strategies is disappearing, and fishing has become the primary economic activity for the great majority of varzeafamilies. As pressure on varzeafisheries has increased, ribeirinhocommunities have attempted to assert control over local varzealakes and exclude fishermen from outside the community. In a number of cases, ribeirinhocommunities have closed lakes to outsiders and established informal lake reserves under local community management. These lake reserves are a promising strategy for managing lake fisheries on a sustainable basis.