The distribution of epiphyte growth-forms in the canopy of a Colombian cloud-forest

Cloud forests are known for their abundance in epiphytes. The growth-form composition of the epiphytic vegetation in the crowns of two tree-species in an upper-andean forest in Colombia is described. Bryophytes formed the bulk of the living epiphytic biomass, with tall turfs and smooth mats (sensu Richards 1984) as commonest growth-forms. Vascular plants and lichens were subordinate to bryophytes. Along the canopy-branches a clear sequence of growth-forms could be demonstrated. Analysis of this gradient by Detrended Correspondence Analysis (DCA), Two Way Indicator Species Analysis (TWINSPAN) and calculation of association-indices between growth-forms revealed two basic groups. One group is typical for the inner canopy, another for the outer canopy. An important determinant of the growth-form composition was the phorophyte species. The vegetational gradient was interpreted in terms of gradual changes in microclimatological factors, water- and nutrient availability and substratumage.     

Material Recycling and the Myth of Landfill Diversion

Proponents of material recycling typically point to two environmental benefits: disposal (landfill/incinerator) reduction and primary production displacement. However, in this paper we mathematically demonstrate that, without displacement, recycling can delay but not prevent any existing end‐of‐life material from reaching final disposal. The only way to reduce the amount of material ultimately landfilled or incinerated is to produce less in the first place; material that is not made needs not be disposed. Recycling has the potential to reduce the amount of material reaching end of life solely by reducing primary production. Therefore, the “dual benefits” of recycling are in fact one, and the environmental benefit of material recycling rests in its potential to displace primary production. However, displacement of primary production from increased recycling is driven by market forces and is not guaranteed. Improperly assuming all recycled material avoids disposal underestimates the environmental impacts of the product system. We show that the potential magnitude of this error is substantial, though for inert recyclables it is lower than the error introduced by improperly assuming all recycled material displaces primary material production. We argue that life cycle assessment end‐of‐life models need to be updated so as not to overstate the benefits of recycling. Furthermore, scholars and policy makers should focus on finding and implementing ways to increase the displacement potential of recyclable materials rather than focusing on disposal diversion targets.     

Closing the Loop on E‐waste: A Multidisciplinary Perspective

This paper describes the challenges faced, and opportunities identified, by a multidisciplinary team of researchers developing a novel closed loop system to recover valuable metals and reduce e‐waste, focusing on mobile phones as a case study. This multidisciplinary approach is contrasted with current top‐down approaches to making the transition to the circular economy (CE). The aim of the research presented here is to develop a product service system (PSS) that facilitates the recovery of valuable functional components and metals from mobile phone circuit boards. To create a holistic solution and limit unintended consequences, in addition to technological solutions, this paper considers appropriate component lifetimes; the (often ignored) role of the citizen in the circular economy; customer interaction with the PSS; environmental life cycle assessment; and social impacts of the proposed PSS. Development of enabling technologies and materials to facilitate recovery of components and metals and to provide an emotionally durable external enclosure is described. This research also highlights the importance of understanding value in the CE from a multifaceted and interdisciplinary perspective.     

Closing the loop on platinum from catalytic converters: Contributions from material flow analysis and circularity indicators

In this study, material flow analysis (MFA) is applied to quantify and reduce the obstacles for advancing a circular economy (CE) of platinum (Pt) from catalytic converters (CC) in Europe. First, the value chain and related stakeholders are mapped out in an MFA‐like model to both facilitate the assessment of stocks and flows, and get a comprehensive view of potential action levers and resources to close‐the‐loop. Then, through the cross analysis of numerous data sources, two MFA are completed: (i) one general MFA, and (ii) one sector‐specific MFA, drawing a distinction between the fate of Pt from (a) light‐duty vehicles, under the European Union's End of Life Vehicle Directive 2000/EC/53, and (b) heavy‐duty and off‐road vehicles. Key findings reveal a leakage of around 15 tons of Pt outside the European market in 2017. Although approximately one quarter of the losses are due to in‐use dissipation, 65% are attributed to insufficient collection and unregulated exports. Comparing the environmental impact between primary and secondary production, it has been estimated that halving the leakage of Pt during usage and collection could prevent the energetic consumption of 1.3 × 10³ TJ and the greenhouse gases emission of 2.5 × 10² kt CO₂ eq. Through the lens of circularity indicators, activating appropriate action levers to enhance the CE performance of Pt in Europe is of utmost importance in order to secure future production of new generations of CC and fuel cells. Moreover, the growing stockpile of Pt from CC in use indicates the need for better collection mechanisms. Also, the CC attrition during use and associated Pt emissions in the environment appears non‐negligible. Based on the scarce and dated publications in this regard, we encourage further research for a sound understanding of this phenomenon that can negatively impact human health.     

Capitalist Contexts for Darwinian Theory: Land, Finance, Industry and Empire

When socio-economic contexts are sought for Darwin’s science, it is customary to turn to the Industrial Revolution. However, important issues about the long run of England’s capitalisms can only be recognised by taking a wider view than Industrial Revolution historiographies tend to engage. The role of land and finance capitalisms in the development of the empire is one such issue. If we historians of Darwin’s science allow ourselves a distinction between land and finance capitalisms on the one hand and industrial capitalism on the other; and if we ask with which side of this divide were Darwin and his theory of branching descent by natural selection aligned, then reflection on leading features of that theory, including its Malthusian elements, suggests that the answer is often and largely, though not exclusively: on the land side. The case of Wallace, socialist opponent of land capitalism, may not be as anomalous for this suggestion as one might at first think. Social and economic historians have reached no settled consensuses on the long-run of England’s capitalisms. We historians of Darwin’s science would do well to import some of these unsettled states of discussion into our own work over the years to come.     

The Moral Economy of Tobacco

ABSTRACT   Even faced with overwhelming evidence that tobacco threatens human health, along with economic developments undermining their status as independent producers, North Carolina tobacco farmers view tobacco production in ways congruent with a moral economy. A shift from independent to contract production of tobacco and the dismantling of government price supports have challenged this moral economy, converting tobacco producers into a quasi–working class dependent on tobacco companies while leading to fewer tobacco farms and an increase in the average tobacco farm's size. These changes signal a shift away from a moral economy of tobacco, although moral-economic dimensions remain. Producers today emphasize different moral dimensions of economic behavior, such as producing quality human beings, than during earlier eras, when moral-economic actors pressed for state intervention in economic crises. Moral-economic principles are not restricted to either non-Western or historical peoples but, rather, influence economic production and ideology in advanced capitalist settings today.     

Integrating dark and light bio-hydrogen production strategies: towards the hydrogen economy

Biological methods of hydrogen production are preferable to chemical methods because of the possibility to use sunlight, CO₂ and organic wastes as substrates for environmentally benign conversions, under moderate conditions. By combining different microorganisms with different capabilities, the individual strengths of each may be exploited and their weaknesses overcome. Mechanisms of bio-hydrogen production are described and strategies for their integration are discussed. Dual systems can be divided broadly into wholly light-driven systems (with microalgae/cyanobacteria as the 1st stage) and partially light-driven systems (with a dark, fermentative initial reaction). Review and evaluation of published data suggests that the latter type of system holds greater promise for industrial application. This is because the calculated land area required for a wholly light-driven dual system would be too large for either centralised (macro-) or decentralised (micro-) energy generation. The potential contribution to the hydrogen economy of partially light-driven dual systems is overviewed alongside that of other bio-fuels such as bio-methane and bio-ethanol.     

一类灰色项时间序列模型及其应用

利用灰色系统理论与时间序列分析,提出了带灰色项的时间序列模型,对这类模型进行了分析,给出了建模与预报方法,并将其应用于我国农业产值问题的预报与研究之中,模型的正确性得到了检验．     

Suites of plant traits in species from different stages of a Mediterranean secondary succession

The aim of this study was to detect suites of traits related to whole plant and seed morphology, phenology and resource use – including water – in species differing in successional status. Twenty traits were measured on 55 species representative of 5 successional stages in Mediterranean southern France, including eight pertaining to phenology and five to water economy. Suites of traits that changed along succession in agreement with the acquisition/conservation trade-off were completed by continuous changes in phenology. Early successional species had leaves with a high specific leaf area that were produced and lost continuously through the growing season. Late-successional species were taller with long-lived, high δ¹³C leaves produced during short periods, most of them persisting during summer, and produced large seeds requiring a long ripening period. Replacement of species occurred with change in strategies of drought survival: early successional species escaped drought by dying before summer; later herbaceous species maintained favourable water status in relation to leaf shedding during summer; late successional trees with a large body allowing access to a large pool of resources, produced dense leaves that could tolerate desiccation. These changes occurred concomitantly with a shift in CSR strategies, using traits related to resource use, plant size and flowering phenology: ruderal herbs were replaced by more stress-tolerant herbs and shrubs throughout the succession, with competitive trees dominating the latest successional stage. These results suggest that the breadth of functional variability found in natura is not predicted by the CSR framework, and calls for a more integrated view of whole plant functioning.     

Current knowledge on non‐native freshwater fish introductions

This review provides a contemporary account of knowledge on aspects of introductions of non‐native fish species and includes issues associated with introduction pathways, ecological and economic impacts, risk assessments, management options and impact of climate change. It offers guidance to reconcile the increasing demands of certain stakeholders to diversify their activities using non‐native fishes with the long‐term sustainability of native aquatic biodiversity. The rate at which non‐native freshwater fishes have been introduced worldwide has doubled in the space of 30 years, with the principal motives being aquaculture (39%) and improvement of wild stocks (17%). Economic activity is the principal driver of human‐mediated non‐native fish introductions, including the globalization of fish culture, whereby the production of the African cichlid tilapia is seven times higher in Asia than in most areas of Africa, and Chile is responsible for c. 30% of the world's farmed salmon, all based on introduced species. Consequently, these economic benefits need balancing against the detrimental environmental, social and economic effects of introduced non‐native fishes. There are several major ecological effects associated with non‐native fish introductions, including predation, habitat degradation, increased competition for resources, hybridization and disease transmission. Consideration of these aspects in isolation, however, is rarely sufficient to adequately characterize the overall ecological effect of an introduced species. Regarding the management of introduced non‐native fish, pre‐introduction screening tools, such as the fish invasiveness scoring kit (FISK), can be used to ensure that species are not introduced, which may develop invasive populations. Following the introduction of non‐native fish that do develop invasive populations, management responses are typified by either a remediation or a mitigation response, although these are often difficult and expensive to implement, and may have limited effectiveness.