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- Cornelissen, Johannes H C, et al.
(author)
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Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
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In: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
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Journal article (peer-reviewed)abstract
- Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide.Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.
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| 2. |
- Camuffo, I, et al.
(author)
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State of the art and eVALUE scope
- 2008
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Reports (other academic/artistic)abstract
- eVALUE will address the real function of ICT-based safety systems and their capability to perform the function through two courses of action: defining and quantifying the function output to be achieved by the safety system and developing the testing and evaluation methods for the ICT-based safety systems. The safety systems within the eVALUE scope are classified into four clusters: longitudinal, lateral and yaw/stability. The fourth cluster remains open for upcoming systems. Based on market availability and penetration rate, the consortium decided to focus on eight preventive or mitigating safety systems: ACC, FCW and CM by braking, in the longitudinal assistance domain; BSD, LDW and LKA, in the lateral assistance domain; and finally, ABS and ESC, in the yaw/stability assistance domain. Following the description of current test and evaluation methods, sensor technologies, system function output and ECUs globally applicable to ICT based safety systems, the report covers these technologies and components for the eight selected systems in detail. As a next step to this deliverable and according to the work plan, concepts for design reviews, physical vehicle testing as well as laboratory testing will be analysed. The result will be an in-depth understanding of the possibilities to investigate and evaluate the eight active safety systems within the first phase of the project. The different concepts will then support the decision about the development of the testing and evaluation methods that are able to point out the safety benefit of those systems in the most representative way.
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| 3. |
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| 4. |
- Westin, Jonas, et al.
(author)
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Analyzing model uncertainty and economies of scale of the Swedish National Freight model to changes in transport demand
- 2016
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In: European Journal of Transport and Infrastructure Research. - : Editorial Board EJTIR. - 1567-7133 .- 1567-7141. ; 16:4, s. 619-632
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Journal article (peer-reviewed)abstract
- The purpose of the paper is to analyze model uncertainty and economies of scale of the Swedish national freight transport model system Samgods to changes in its zone-to-zone base matrices. Even though economies of scale is important for freight transport, few studies analyze model uncertainty and economies of scale at a national level. Compared to many large scale network-based freight models working on aggregated transport flows, an important feature in Samgods is that it simulates logistics behavior at a disaggregated firm level. The paper studies effects on total tonne- and vehicle-kilometre, modal split, consolidation and logistics costs when the base matrices are scaled up and down and estimates economies of scale for Swedish freight transports. The results indicate that the logistics model can find new logistics solutions for larger demand volumes, mainly by shifting freight to sea transport. If transport volume increases with one percent, average logistics cost per tonne is reduced by around 0.5 percent. Part of the cost reduction comes from increased consolidation of shipments due to larger transport volumes. The results derived in the paper can serve as a reference for empirical validation and comparisons with other large scale freight models. The paper is a first contribution that tries to fill the knowledge gap on the impact of base matrices on transport model outcomes, such as economies of scale, in the context of a full-fledged real-world freight transport model.
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