| 1. |
- Hedlund, Katarina, et al.
(författare)
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Mycorrhizal colonization of plants in set-aside agricultural land
- 2002
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Ingår i: Applied Soil Ecology. - 0929-1393. ; 19:1, s. 71-78
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural overproduction has led the European Union to encourage long-term abandonment of agricultural land and the adoption of management practices which enhance transition to semi-natural grassland or forest. This paper reports the results of a field study conducted in newly abandoned agricultural land where the development of the mycorrhizal community was investigated in response to manipulation of the above-ground vegetation. The field site consisted of plots where the plant diversity was managed by (1) sowing 15 plant species, (2) sowing four plant species, and (3) allowing plots to be naturally colonized by plants. The plant mixture contained grasses, legumes and forbs that were all expected to occur on the site following succession. Each of the low diversity replicates contained a different subset of the high diversity mixture, in order to avoid confounding diversity effects with sampling effects. A subset of these plots was inoculated with soil cores from a later successional stage and the experiment was arranged in a randomized block design. The catch plants, Fagus sylvatica, Picea abies and Plantago lanceolata, were planted in the experimental plots and the presence of ecto- or arbuscular mycorrhizal (AM) fungi on their roots was determined. The level of AM colonization of P. lanceolata and the ectomycorrhizal colonization of F. sylvatica was lower in the sown treatments with high and low plant diversity compared to areas that were naturally colonized by plants. The survival of catch plants of the tree species was also higher in the naturally colonized plots. Soil inoculations had no effect on either of the mycorrhizal types or the survival of catch plants. The establishment of non-introduced woody plant species was more successful in the naturally colonized treatments. (C) 2002 Elsevier Science B.V All rights reserved.
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| 2. |
- Brewin, C R, et al.
(författare)
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Psychological theories of posttraumatic stress disorder
- 2003
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Ingår i: Clinical Psychology Review. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0272-7358 .- 1873-7811. ; 23:3, s. 339-376
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Forskningsöversikt (refereegranskat)abstract
- We summarize recent research on the psychological processes implicated in posttraumatic stress disorder (PTSD) as an aid to evaluating theoretical models of the disorder. After describing a number of early approaches, including social-cognitive, conditioning, information-processing, and anxious apprehension models of PTSD, the article provides a comparative analysis and evaluation of three recent theories: Foa and Rothbaum's [Foa, E. B. & Rothbaum, B. O. (1998). Treating the trauma of rape: cognitive behavioral therapy for PTSD. New York: Guilford Press] emotional processing theory; Brewin, Dalgleish, and Joseph's [Psychological Review 103 (1996) 670] dual representation theory; Ehlers and Clark's [Behaviour Research and Therapy 38 (2000) 319] cognitive theory. We review empirical evidence relevant to each model and identify promising areas for further research. (C) 2003 Elsevier Science Ltd. All rights reserved.
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| 3. |
- Gormsen, Dagmar, et al.
(författare)
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The influence of collembolans and earthworms on AM fungal mycelium
- 2004
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 27:3, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- Arbuscular mycorrhizal (AM) mycelia are dependent on contact with plant roots for spore formation. In this study, earthworms and collembolans were regarded as potential dispersal vectors of AM fungal spores and hyphae, and we determined how they influenced the extension of AM fungi from host plant roots. Plantago lanceolata seedlings were grown in a mesh bag with an AM inoculurn of dried soil and root pieces from a set-aside agricultural field. The bag was placed in a growth box that was filled with a mixture of irradiated soil and sand, into which fungal hyphae could grow while roots were retained by the mesh. Three treatments with 15 replicates each were established with an addition of either Lumbricus rubellus, Folsomia candida or no soil fauna into the root-free soil. Five replicates of each treatment were harvested after 6, 10 and 15 weeks. The extension of the AM fungi was determined by measuring PLFA 16:1w5 and NLFA 16:1w5 as signature compounds of AM fungal biomass, spore production and mycorrhizal inoculum potential on P lanceolata seedlings. After 10 weeks, all indicators of AM fungal growth showed that the fungi had extended into the whole growth box. Plant shoot biomass of the host plants was greater in the presence of earthworms than other treatments, and the contents of PLFA 16:1w5 were greater in the earthworm than in the collembolan treatment. The reduced amount of PLFA 18:2w6,9 in the collembolan treatment relative to other treatments suggests that saprophytic fungi provided a food source for the collembolans. Spore production and mycorrhizal inoculurn potential were not affected by the presence of soil fauna. We conclude that the biomass of AM fungi was stimulated by earthworms, but that fungal dispersal over 20 cm was not influenced. (C) 2004 Elsevier B.V. All rights reserved.
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| 4. |
- Jonsson, Patrik, 1967
(författare)
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Towards an Holistic Understanding of Disruptions in Operations Management
- 2000
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Ingår i: Journal of Operations Management. - 1873-1317 .- 0272-6963. ; 18:6, s. 701-718
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Tidskriftsartikel (refereegranskat)abstract
- The paper reviews the literature on maintenance management, integrates key dimensions of maintenance within a taxonomy of maintenance configurations, and explores the impact of differing configurations on contextual factors and operational performance. 'Prevention', 'hard maintenance integration' and 'soft maintenance integration' were identifiedas key maintenance variables. Data were collected from 253 Swedish manufacturing companies, and three distinct clusters were identified. 'Proactive Maintainers' emphasized preventive maintenance policies. 'IT Maintainers' relied on computerized and company-wide integrated information systems for maintenance. 'Maintenance Laggers' emphasized all maintenance dimensions to lesser extent than the others. The importance of maintenance prevention and integration differ between contexts. There were subtle performance differences across identified configurations, but preventive and integrated maintenance were more important for companies seeking competitive process control and flexibility. There existed no group with any great emphasis on all three maintenance dimensions, but attaining truly high performance may require a rare mix ofthe three dimensions. This mix of variables could constitute a hypothesized 'World Class Maintenance' group.
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| 5. |
- Söderberg, Katarina, et al.
(författare)
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The microbial community in the rhizosphere determined by community-level physiological profiles (CLPP) and direct soil- and cfu-PLFA techniques
- 2004
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Ingår i: Applied Soil Ecology. - : Elsevier BV. - 0929-1393. ; 25:2, s. 135-145
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Tidskriftsartikel (refereegranskat)abstract
- The composition of the microbial community in the rhizosphere was investigated using three different techniques: direct soil-phospholipid fatty acid (PLFA), cfu-PLFA (using culturable, bacteria only) and community-level physiological profiles (CLPP) using Biolog GN microtitre plates. All three techniques showed that the rhizosphere bacterial community differed from the bulk soil community, when pea plants were grown in pots. The two PLFA techniques also indicated that the effect of roots on microbial communities was greater than differences in the PLFA pattern between different bulk soils. The difference was most prominent using the direct soil-PLFA technique. Both PLFA techniques indicated that gram-negative bacteria were relatively more abundant in the rhizosphere, while PLFAs indicative of gram-positive bacteria were relatively more common in bulk soil samples. The results obtained with the direct soil-PLFA method did not differ between rhizosphere samples taken along a pea root, while this was the case with both the cfu-PLFA technique and the CUP method. According to both techniques, the differences in community composition were greatest near the root tip. Different plant species exhibited different microbial community composition in the rhizosphere, as judged from all three methods, when four different plant species were compared. In all cases, Trifolium differed most from the other species (three different grasses). Although all three methods were found to be suitable for rhizosphere studies, the CLPP method appeared less suitable than the two PLFA methods, since less of the variation in the data could usually be explained.
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