| 1. |
- Bergkvist, Bo, et al.
(författare)
-
Pools and fluxes of carbon in three Norway spruce ecosystems along a climatic gradient in Sweden
- 2008
-
Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 89:1, s. 7-25
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents an integrated analysis of organic carbon (C) pools in soils and vegetation, within-ecosystem fluxes and net ecosystem exchange (NEE) in three 40-year old Norway spruce stands along a north-south climatic gradient in Sweden, measured 2001-2004. A process-orientated ecosystem model (CoupModel), previously parameterised on a regional dataset, was used for the analysis. Pools of soil organic carbon (SOC) and tree growth rates were highest at the southernmost site (1.6 and 2.0-fold, respectively). Tree litter production (litterfall and root litter) was also highest in the south, with about half coming from fine roots (< 1 mm) at all sites. However, when the litter input from the forest floor vegetation was included, the difference in total litter input rate between the sites almost disappeared (190-233 g C m(-2) year(-1)). We propose that a higher N deposition and N availability in the south result in a slower turnover of soil organic matter than in the north. This effect seems to overshadow the effect of temperature. At the southern site, 19% of the total litter input to the O horizon was leached to the mineral soil as dissolved organic carbon, while at the two northern sites the corresponding figure was approx. 9%. The CoupModel accurately described general C cycling behaviour in these ecosystems, reproducing the differences between north and south. The simulated changes in SOC pools during the measurement period were small, ranging from -8 g C m(-2) year(-1) in the north to +9 g C m(-2) year(-1) in the south. In contrast, NEE and tree growth measurements at the northernmost site suggest that the soil lost about 90 g C m(-2) year(-1).
|
|
| 2. |
- Björk, Robert G., 1974, et al.
(författare)
-
Long-term warming effects on root morphology, root mass distribution, and microbial activity in two dry tundra plant communities in northern Sweden
- 2007
-
Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 176:4, s. 862-873
-
Tidskriftsartikel (refereegranskat)abstract
- center dot Effects of warming on root morphology, root mass distribution and microbial activity were studied in organic and mineral soil layers in two alpine ecosystems over > 10 yr, using open-top chambers, in Swedish Lapland. center dot Root mass was estimated using soil cores. Washed roots were scanned and sorted into four diameter classes, for which variables including root mass (g dry matter (g DM) m(-2)), root length density (RLD; cm cm(-3) soil), specific root length (SRL; m g DM-1), specific root area (SRA; m(2) kg DM-1), and number of root tips m(-2) were determined. Nitrification (NEA) and denitrification enzyme activity (DEA) in the top 10 cm of soil were measured. center dot Soil warming shifted the rooting zone towards the upper soil organic layer in both plant communities. In the dry heath, warming increased SRL and SRA of the finest roots in both soil layers, whereas the dry meadow was unaffected. Neither NEA nor DEA exhibited differences attributable to warming. center dot Tundra plants may respond to climate change by altering their root morphology and mass while microbial activity may be unaffected. This suggests that carbon may be incorporated in tundra soils partly as a result of increases in the mass of the finer roots if temperatures rise.
|
|
| 3. |
- Björklund, Elisabeth, 1945-
(författare)
-
Att erövra litteracitet : Små barns kommunikativa möten med berättande, bilder, text och tecken i förskolan
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is based on an ethnographic field study among a group of monolingual children from one and a half to three years old at a pre-school in a Swedish village. The primary aim of the study has been to gain knowledge about how young children conquer and express literacy in their everyday lives. One assumption was that children are active and competent in their search for meaning when dealing with texts, signs and images. A second aim has been to investigate whether children’s literacy could have an impact on the social and cultural context of pre-school.Research questions addressed in the study focus on children’s participation in literacy events and their actions in literacy practice. An additional question was whether children were contributing to literacy practice when interacting with other children in the group.The theoretical framework draws upon socio-cultural theory. The empirical material consists of video recordings and the focus of observation has been on children’s actions related to literacy, expressed as early literacy, including reading and writing as well as telling and retelling narratives, singing and other verbal and non verbal communication. In children’s literacy events and literacy practice the specific context was of central interest. All the material collected has been transcribed and transferred into text and constitutes the basis for analyzing what children are performing in actual events and practices. The guiding principle for description was at first to give a close reproduction of children’s verbal utterances and their acting linked to the concept of early literacy. Secondly, the aim was to describe and analyze whether the utterances and actions could be linked to the specific social and cultural context.The analysed material demonstrates how children participate and interact with each other while engaged in literacy and the material also displays the content of their communication. Two different kinds of literacy appear: one is narrative tellings and the other is reading and drawing/writing. A deeper analysis shows that children are building knowledge of telling and also creating a specific manifesto of literacy. The children also underline what they are doing through verbal expressions where they defined themselves as both readers and writers.The result gives a contribution to new knowledge and an understanding of early literacy among very young children as something they have created in pre-school as a social and cultural environment. Literacy in the studied group of children uncovers many more expressions, including several actions with regard to written material, than we usally relate to the youngest children in pre-school.
|
|
| 4. |
- Burström, Lage, 1954-, et al.
(författare)
-
Acute effects of vibration on thermal perception thresholds
- 2006
-
Ingår i: Diagnosis of injuries caused by hand-transmitted vibration - 2nd International workshop, Göteborg, 2006. - : Springer Science and Business Media LLC.
-
Konferensbidrag (refereegranskat)abstract
- Objective This study focuses on the acute effects of vibration and how vibrations influence the measures of the thermal perception thresholds during different vibration magnitudes, frequencies, and durations.Methods The fingers of ten healthy subjects, five males and five females, were exposed to vibration under 16 conditions with a combination of different frequency, intensity and exposure time. The vibration frequency was 31.5 and 125 Hz and exposure lasted between 2 and 16 min. The energy-equivalent frequency weighted acceleration, according to ISO 5349-1, for the experimental time of 16 min was 2.5 or 5.0 m/s(2) (r.m.s.), corresponding to a 8-h equivalent acceleration, A(8) of 0.46 and 0.92 m/s(2), respectively. A measure of the thermal perception of cold and warmth was conducted before the different exposures to vibration. Immediately after the vibration exposure the acute effect was measured continuously on the exposed index finger for the first 75 s, followed by 30 s of measures at every minute for a maximum of 10 min. If the subject's thermal thresholds had not recovered, the measures continued for a maximum of 30 min with measurements taken every 5 min.Results For all experimental conditions and 30 s after exposure, the mean changes of the thresholds compared with the pre-test were found to be 0.05 and -0.67C for the warmth and cold thresholds, respectively. The effect of the vibration exposure was only significant on the cold threshold and only for the first minute after exposure when the threshold was decreased. The warmth threshold was not significantly affected at all. The frequency and the exposure time of the vibration stimuli had no significant influence on the perception thresholds for the sensation of cold or warmth. Increased equivalent frequency weighted acceleration resulted in a significant decrease of the subjects' cold threshold, not the warmth. The thresholds were unaffected when changes in the vibration magnitude were expressed as the frequency weighted acceleration or the unweighted acceleration.Conclusion When testing for the thermotactile thresholds, exposure to vibration on the day of a test might influence the results. Until further knowledge is obtained the previous praxis of 2 h avoidance of vibration exposure before assessment is recommended.
|
|
| 5. |
- Cornelissen, Johannes H C, et al.
(författare)
-
Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
-
Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 6. |
- Eliasson, Ingegärd, 1961, et al.
(författare)
-
Climate and behaviour in a Nordic city
- 2007
-
Ingår i: LANDSCAPE AND URBAN PLANNING. - : Elsevier BV. - 0169-2046 .- 1872-6062. ; 82:1-2, s. 72-84
-
Tidskriftsartikel (refereegranskat)abstract
- Four urban public spaces, representing various designs and microclimates, were investigated in Gothenburg, Sweden, in order to estimate how weather and microclimate affect people in urban outdoor environments. The research strategy was both multidisciplinary and interdisciplinary and included scientists from three disciplines: architecture, climatology and psychology. The project is based on common case studies carried out during four seasons, including measurements of meteorological variables, interviews and observations of human activity at each place. Multiple regression analysis of meteorological and behavioural data showed that air temperature, wind speed and clearness index (cloud cover) have a significant influence on people's assessments of the weather, place perceptions and place-related attendance. The results support the arguments in favour of employing climate sensitive planning in future urban design and planning projects, as the physical component of a place can be designed to influence the site-specific microclimate and consequently people's place-related attendance, perceptions and emotions.
|
|
| 7. |
- Eliasson, Ingegärd, 1961, et al.
(författare)
-
Klimatet vänder turistströmmar
- 2009
-
Ingår i: Miljöforskning. ; 1, s. 24-25:1, s. 24-25
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 8. |
- Gullberg, Annica, et al.
(författare)
-
Prospective teachers’ initial conceptions about pupils’ understanding of science and mathematics
- 2008
-
Ingår i: European Journal of Teacher Education. - : Informa UK Limited. - 0261-9768 .- 1469-5928. ; 31:3, s. 257-278
-
Tidskriftsartikel (refereegranskat)abstract
- Earlier reports have shown that prospective teachers' conceptions about teaching science to a high degree are resistant and do not change substantially during the teacher-training programme. In our investigation we elucidate the prospective teachers' initial conceptions about pupils' understanding of science and mathematics. We applied 'The Lesson Preparation Method' and used a phenomenographic approach in order to reveal the range of conceptions that the prospective teachers hold. A third of the prospective teachers did not consider pupils' conceptions when planning lessons. The rest of the 32 participants expressed awareness; some of the prospective teachers even referred to subject-specific teaching experience. Also regarding the prospective teachers' conceptions about pupils' knowledge and beliefs, as well as about pupils' difficulties, there was a significant diversity. By raising these issues about pedagogical content knowledge the prospective teachers' conceptions can be extended and developed during the education.
|
|
| 9. |
- Haglund, Björn, 1962, et al.
(författare)
-
Afterschool Programs and Leisure-Time Centres: Arenas for Learning and Leisure
- 2009
-
Ingår i: World Leisure Journal. - : Informa UK Limited. - 0441-9057 .- 1607-8055 .- 2333-4509. ; 51:2, s. 116-129
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract Afterschool programs in the United States and leisure-time centres in Sweden could emphasize children’s leisure as well as be of importance to children’s learning. However, in both cases, the association to leisure is mostly ignored and the acceptance is not widely practiced. Instead, other discourses that partly are more related to the field of education serve as a guide for programming in afterschool programs and leisure-time centres. The authors present the argument that afterschool programs and leisure-time centres could be more associated with leisure activities and presented in a new way with the guidance from the field of leisure that also could be beneficial for educational research. Existing definitions of leisure, and their possible consequences for the activities, are discussed in terms of the framework of afterschool programs and leisure-time centres. The authors argue that knowledge grounded in understanding the importance of leisure and its potential to develop and satisfy people could be a means to develop both the activities and the current work of the staff in afterschool programs and leisure-time centres.
|
|
| 10. |
|
|
