56 research outputs found

    Growth, nutrient uptake and ectomycorrhizal function in Pinus sylvestris plants exposed to aluminium and heavy metals

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    The potential role of aluminium (Al) toxicity to trees has been of particular concern to forest owners and scientists since the early 1980’s when Ulrich hypothesised that both A1 and heavy metals were involved in forest dieback because of their increased concentrations in soil due to acidfication. Since then, numerous studies have examined the effects of metals upon nutrient uptake by plants. However, most of these investigations have been carried out in the absence of mycorrhizal fungi, which, in most ecosystems, are crucial components in nutrient uptake by plants. The present work focused on the effects of elevated concentrations of A1 and heavy metals on Scots pine (Pinus sylvestris L.) and the potential role of ectomycorrhiza in modifying these effects. Ectomycorrhizal colonisation enhanced the growth and nutrient uptake by seedlings. To some extent, colonisation also alleviated reduced nutrient uptake which was a feature of seedlings growing in the presence of the metals. This effect was particularly noticeable with respect to P uptake. In general, mycorrhizal seedlings grew better and had an improved P, K, Mg and S status compared with non-mycorrhizal seedlings. Significant differences were also found in nutrient uptake among seedlings colonised by different fungi. One fungus, Hebeloma cf. longicaudum, was more sensitive to the A1 treatment than the pine seedlings. The use of the base cation / A1 ratio as an indicator of the potential detrimental effects to trees to acidification and A1 is discussed. The production of oxalic acid was found to increase when mycorrhizal and nonmycorrhizal seedlings were exposed to A1 or Cu. Colonisation by Suillus variegatus or Rhizopogon roseolus, in particular, resulted in a marked increase. These results demonstrate that there is a capacity, especially by certain ectomycorrhizal fungi, for increased production of the metal-chelating oxalic acid when root systems are exposed to increased levels of metals. In a field experiment, spraying with solutions of Ni/Cu sulphate or acidified water did not affect the growth of small pine trees. As part of the same experiment, defoliation was carried out on the pine trees in order to reduce carbon supply below-ground. Defoliation altered the proportions of different mycorrhizal morphotypes: Tuberculate types decreased and smooth types increased. The treatment did not affect the level of mycorrhizal colonisation of short roots, which was nearly 100%

    Strategic, fundamental and means objectives of different stakeholders in collaboration between universities and surrounding society

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    Universities play an important role in the development of society. However, it is not always clear what the objectives of collaboration between a Higher Education Institution (HEI) and external stakeholders from the surrounding society are. In this study, value-focused thinking was applied to construct structures of strategic, fundamental and means objectives of different stakeholders working practically with collaboration between an HEI and the surrounding society. Respondents in three groups of stakeholders from a university and external parties were interviewed. Focus in this study is on general objectives of collaboration between an HEI and the surrounding society. Based on the interviews and feedback, objectives were identified and SSFMO (Structure of Strategic, Fundamental and Means Objectives) was constructed from each respondent’s answer. Generally, the fundamental objectives differed more between the stakeholders than the means objectives did. How SSFMOs could be used in practical collaboration projects is discussed in the paper

    Does visual saliency affect decision-making?

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    In the present study, we explore potential effects of visual saliency on decision quality in context of multi-criteria decision-making (MCDM). We compare two visualization techniques: parallel coordinates (PC) and scatterplot matrices (SPM). We investigate the impact of saliency facilitated by means of either color or size. The saliency and visualization techniques were factors in our analysis, and effects were evaluated in terms of decision quality, attention, time on task, and confidence. Results show that the quality of choice and attention were comparable for all saliency conditions when SPM was used. For PC, we found a positive effect of color saliency both on the quality of choice and on attention. Different forms of saliency led to varying times on task in both PC and SPM; however, those variations were not significant. A comparison of PC and SPM shows, users spent less time on the task, obtained better decision quality, and were more confident with their decision when using PC. To summarize, our findings suggest that saliency can increase attention and decision quality in MCDM for certain visualization techniques and forms of saliency. Another contribution of this work is the novel suggestion of the method to elicit of users’ preferences; its potential benefits are discussed in the end of the paper

    How do people aggregate value? An experiment with relative importance of criteria and relative goodness of alternatives as inputs

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    The concept of importance of criteria is used as a central element in several decision making contexts, specifically in value aggregation, e.g. as an input to decision support tools. For example, in the analytic hierarchy process (AHP) decision makers are asked to estimate how much more important one criterion is than another. However, it is not clear how people understand aggregation models based on importance of criteria in decision making situations. The purpose of this descriptive study is to investigate if people find an aggregation model in simple value aggregation tasks which remind of the way AHP elicits the input. Further, the purpose is to investigate if people's tendency to find a model depends on their cognitive abilities. In an exploratory laboratory experiment, participants assessed which of two alternatives is the best, based on information about the importance of two criteria and how good the two alternatives are compared to each other with respect to these criteria. The results confirm that people are willing to use importance of criteria and goodness of alternatives as input in value aggregations and show three main models for aggregation. More participants with higher numeracy applied a clear model compared to those with lower numeracy. None of the identified models was one of AHP's models but one of them reminded of one of the ways input can be aggregated in the AHP. The three models identified in the experiment are based on lexicographic order, multiplication and a combination of multiplication and addition. How the results could be used in a prescriptive context is discussed in the paper

    Geospatial Decision-Making Framework Based on the Concept of Satisficing

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    Decision-making methods used in geospatial decision making are computationally complex prescriptive methods, the details of which are rarely transparent to the decision maker. However, having a deep understanding of the details and mechanisms of the applied method is a prerequisite for the efficient use thereof. In this paper, we present a novel decision-making framework that emanates from the need for intuitive and easy-to-use decision support systems for geospatial multi-criteria decision making. The framework consists of two parts: the decision-making model Even Swaps on Reduced Data Sets (ESRDS), and the interactive visualization framework. The decision-making model is based on the concept of satisficing, and as such, it is intuitive and easy to understand and apply. It integrates even swaps, a prescriptive decision-making method, with the findings of behavioural decision-making theories. Providing visual feedback and interaction opportunities throughout the decision-making process, the interactive visualization part of the framework helps the decision maker gain better insight into the decision space and attribute dependencies. Furthermore, it provides the means to analyse and compare the outcomes of different scenarios and decision paths

    GISwaps : A new method for decision making in continuous choice models based on even swaps

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    This article describes how continuous GIS-MCDM problems are commonly managed by combining some weighting method based on pairwise comparisons of criteria with an aggregation method. The reliability of this approach may be questioned, though. First, assigning weights to criteria, without taking into consideration the actual consequences or values of the alternatives, is in itself controversial. Second, the value functions obtained by this approach are in most cases linear, which is seldom the case in reality. The authors present a new method for GIS-MCDM in continuous choice models based on Even Swaps. The method is intuitive and easy to use, based on value trade-offs, and thus not relying on criteria weighting. Value functions obtained when using the method may be linear or non-linear, and thereby are more sensitive to the characteristics of the decision space. The performed case study showed promising results regarding the reliability of the method in GIS-MCDM context

    Multi-criteria reasoning models for value aggregation in wind power permit application assessment

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    Assessment of an application for wind power establishment is a multi-criteria problem including the coreproblem: whether to grant permission or not. In Sweden, County Administrative Boards decide the outcomes of these kinds of applications. Five permit officers were interviewed to investigate the difficultiesand the type of value aggregation in this work, and to test reasoning models as possible decision supporttools. The commonly used type of aggregation was condition-based aggregation. Aggregation based onvalue differences, which means weighing together aspects for and against the wind power establishment,was considered difficult to apply by the respondents. Most of them agreed that some of the aspects thatspeak against granting permission could be aggregated but that aggregation of all aspects would be harddue to differences between aspects. In addition, the value of the main aspect that speaks for permission,climate friendly energy supply, is very difficult to estimate. Thus, aggregation based on value differencesis a difficult question and how it could be performed is discussed in the paper. If policymakers wish tomake it possible to take both positive and negative aspects into consideration and to discuss thetrade-offs transparently, the investigated method can be a way forward
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