| 1. |
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| 2. |
- Abrahamsson, Markus, et al.
(författare)
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Saproxylic beetle assemblages in artificially created high-stumps of spruce (Picea abies) and birch (Betula pendula/pubescens) – does the surrounding landscape matter?
- 2009
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Ingår i: Insect Conservation and Diversity. - : Wiley. - 1752-458X .- 1752-4598. ; 2, s. 284-294
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Tidskriftsartikel (refereegranskat)abstract
- Abstract. 1. To create high-stumps (snags) is a common conservation action during final felling in Swedish production forests. However, many wood-living beetle species are only found in certain areas with higher overall biodiversity, so called hotspots. It has been argued that it is efficient to concentrate conservation efforts to hotspots. 2. The saproxylic beetle fauna was sampled on ten clearcuts inside hotspots and ten clearcuts outside the hotspots. They were collected with window traps mounted on 2- and 4-year-old spruce and birch high-stumps. We also used environmental data (e.g. tree species composition) to confirm differences between the surroundings of two, the clearcut types. 3. High-stumps on the hotspot clearcuts did not attract more saproxylic beetle species, or red-listed species, than high-stumps outside the hotspots. The environmental data showed that the clearcuts differed in several important aspects, for instance, were there a higher proportion of broadleaved trees around the hotspot compared with the clearcuts outside the hotspots. In a Canonical Correspondence Analysis, the proportion of coniferous and broadleaved forest was an important explanatory variables. The hotspot variable did contribute significantly in explaining the beetle composition on the birch high-stumps, but not on the spruce high-stumps. 4. In general, the study suggests that concentrating high-stumps to hotspot areas will not benefit more species. However, the result indicates birch high-stumps could be prioritised in a biologically rich landscape. The hotspot effect may be more noticeable in the future as the high-stumps decay and their importance for late successional species increase
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| 3. |
- Felton, Adam, et al.
(författare)
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Forest biodiversity and ecosystem services from spruce-birch mixtures : The potential importance of tree spatial arrangement
- 2022
-
Ingår i: Environmental Challenges. - : Elsevier BV. - 2667-0100. ; 6
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Forskningsöversikt (refereegranskat)abstract
- There is increasing empirical support for the biodiversity and ecosystem service (ES) benefits of mixed-species production forests. However, few studies control for the spatial arrangement of the trees within mixtures to determine the influence that clustering the tree species (patch scale mixtures), versus evenly dispersing them (intimate scale mixtures), may have for biodiversity and ES outcomes. To highlight the potential implications of altering tree spatial arrangement in mixtures, and the need to fill related knowledge gaps, here we provide a qualitative multi-disciplinary overview of ecological and socio-economic drivers with the potential to alter biodiversity, ecosystem services, and management-related outcomes from patch versus intimate scale mixtures. We focused our overview on even-aged mixtures of Norway spruce (Picea abies) and birch (Betula pendula or B. pubescens) in Sweden, which enabled us to contrast findings within a biogeographical and silvicultural setting. Specifically, we targeted implications for biodiversity (understory vascular plants, epiphytic lichens, saproxylic beetles, birds), biomass production, harvesting costs, management ease, recreation and aesthetics, cervid game, as well as abiotic and biotic risks (wind, fire, pathogens, pests, browsing damage). In the absence of direct empirical evidence, we primarily relied on expert inference from theory and relevant empirical studies sourced from the Fennoscandian region, and further afield if needed. Collectively these efforts allowed us to develop a number of informed hypotheses indicating that for spruce-birch mixtures in this region, patch scale mixtures may have the potential to favour the diversity of several forest dependant taxonomic groups, cervid game and reduce harvesting costs, whereas intimate mixtures may have the potential to reduce pathogen and pest damage, and likewise, potentially benefit production outcomes. Current knowledge was too limited, inconsistent or context dependant to even tentatively infer outcomes for fire risk, wind damage, browsing damage, management ease, recreational and aesthetic outcomes. We emphasize that our hypotheses require testing, but are sufficient to (1) highlight the likely importance of spatial-scale to biodiversity and ecosystem services outcomes in mixed-species production forests, (2) caution against generalization from mixture studies that lack scale considerations, and (3) motivate the targeted consideration of spatial grain in future mixture studies.
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| 4. |
- Niklasson, Mats, et al.
(författare)
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Sensorimotor therapy : Physical and psychological regressions contribute to an improved kinesthetic and vestibular capacity in children and adolescents with motor difficulties and concentration problems
- 2010
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Ingår i: Social behavior and personality. - : Scientific Journal Publishers Ltd. - 0301-2212 .- 1179-6391. ; 38:3, s. 327-346
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Tidskriftsartikel (refereegranskat)abstract
- Our aim was to gain increased understanding of the effects of sensorimotor therapy on the physical and psychological development of children and young people when using the method Retraining for Balance. The records of 8 children who had completed the program were randomly selected from a cohort of 232 with sensorimotor difficulties and concentration problems. The participants, 7 boys and 1 girl, averaged 9 years of age. The Empirical Phenomenological Psychological method (the EPP-method, Gunmar Karlsson, 1995) was used for this analysis, which resulted in 29 categories which yielded 3 overarching themes: a) the introduction of sensorimotor exercises, b) regression to earlier sensorimotor and psychological behaviors, and c) transformations in which the sensorimotor and psychological skills of the children matured and developed. The themes formed the kinesthetic-vestibular developmental model illustrating how sensorimotor exercises push the therapy process forward while recurrent regressions are followed by positive developmental phases. The results of the study were generalized to the remaining 224 children in the cohort by comparing each individual’s records to the kinesthetic-vestibular model.
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| 5. |
- Niklasson, Mats, et al.
(författare)
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Sensorimotor Therapy : Using Stereotypic Movements and Vestibular Stimulation to Increase Sensorimotor Proficiency of Children with Attentional and Motor Difficulties
- 2009
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Ingår i: Perceptual and Motor Skills. - : SAGE Publications. - 0031-5125 .- 1558-688X. ; 108:3, s. 643-669
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Tidskriftsartikel (refereegranskat)abstract
- The current naturalistic study examined whether sensorimotor therapy utilizing the training program, Retraining for Balance, might be an appropriate technique for sensorimotor proficiency. The 232 children (181 boys, 51 girls), whose mean age was 9.3 yr. (SD = 2.7), presented attentional and motor difficulties (according to the School Health Care) as indicated by their parents before starting therapy. The children were divided into three groups, i.e., a younger group (7 yr. old or younger, n = 65), a middle group (8 to 10 yr. old, n =91), and an older group (11 yr. old or older, n = 76). The program has seven parts, including fetal and neonatal movements, vestibular and auditory perceptual stimulation, and gross motor movements, among others. The treatment period was close to 3 yr. on the average. Analyses in a repeated-measures design indicated significant improvement of sensorimotor skills among the three age groups, but the older children performed better than the others on several tests. There were only a few sex differences. Retraining for Balance may be a functional technique for training children and youth with sensorimotor difficulties and might constitute a complement to regular treatment of Developmental Coordination Disorder, Learning Disability, and ADHD, but controlled studies are necessary before more decisive conclusions can be drawn.Read More: http://www.amsciepub.com/doi/abs/10.2466/pms.108.3.643-669
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| 6. |
- Agestam, E, et al.
(författare)
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Productivity scenarios for the Asa Forest Park
- 2002
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Ingår i: Developing principles and models for sustainable forestry in Sweden. - 1402009992 ; , s. 355-380
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Amsten, Karin, et al.
(författare)
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Fire- and herbivory-driven consumer control in a savanna-like temperate wood-pasture: An experimental approach
- 2021
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 109, s. 4103-4114
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Tidskriftsartikel (refereegranskat)abstract
- 1. Fire and herbivory are fundamental top-down processes, structuring grass-tree ratios in ecosystems across a diversity of climates. Both are plant consumers that can strongly control the recruitment of woody seedlings and saplings to taller height classes. Without consumer control, many grass-dominated ecosystems would convert into woodlands or forests. While extensively studied in savannas, few have explored the effects of these disturbance regimes on woody recruitment under temperate conditions.2. We exposed saplings of five common European tree species to fire and herbivory in a full factorial experiment in a savanna-like wood-pasture. After 3 years, we evaluated the effects of fire and herbivory on tree sapling survival and height increment. The tree species used, varying in traits and in expected response to fire and herbivory, were Scots pine Pinus sylvestris, Norway spruce Picea abies, European oak Quercus robur, Silver birch Betula pendula and Small-leaved lime Tilia cordata.3. Fire and herbivory had a negative effect on sapling survival for all species except for Q. robur, which was not affected by fire. Both processes reduced height increment of B. pendula, while only herbivory reduced the height increment of P. sylvestris and Q. robur. At the same time, B. pendula and P. sylvestris had some of the highest increments, together with P. abies, which had unaffected height increment in all treatments. T. cordata, on the other hand, had a negative height increment across all treatments. Overall, the combined effect of fire and herbivory was similar to the effect of herbivory alone on both survival and height increment, indicating no additional effect of fire when herbivores were present.4. Synthesis. Our experiment showed how fire and herbivory can strongly affect the recruitment of European temperate tree saplings on a wood-pasture, potentially leading to comparable consumer control described for ecosystems elsewhere (e.g. savannas). Two strategies to deal with fire and herbivory were identified: tolerance (Q. robur) and avoidance (P. sylvestris and B. pendula). We conclude that both fire and herbivory may have been important drivers of structure and species composition in open ecosystems in temperate Europe in the past.
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| 8. |
- Amsten, Karin, et al.
(författare)
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Pyric herbivory in a temperate European wood-pasture system
- 2024
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Ingår i: Journal of Applied Ecology. - 0021-8901 .- 1365-2664. ; 61, s. 1081-1094
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Tidskriftsartikel (refereegranskat)abstract
- The term pyric herbivory was first introduced in 2009, describing how fire shapes herbivory as burned areas attract herbivores and, simultaneously, herbivory shapes fuel load and fire behaviour. Pyric herbivory results in a mosaic of patches with varying levels of herbivory and grazing intensity fire intensity and frequency. The importance of pyric herbivory for ecosystem heterogeneity and biodiversity has been described for North American, Australian and African systems, but the concept remains largely untested in a European context. We introduced fire and herbivory in a full-factorial experiment in a temperate European wood-pasture system to test whether pyric herbivory operates in ways comparable to grassy systems elsewhere in the world. Using camera traps, we observed the behaviour of cattle in burned subplots (49 m2) compared with unburned subplots. We measured grass height and the proportion of the subplot that burned as variables affecting cattle preference and to assess how grazing affects fire behaviour. We also examined the effect on plant species and life-form composition after six seasons of treatment. Cattle spent more time grazing in burned than in unburned subplots in the most productive paddock, where a larger proportion of the subplot burned. The proportion of a subplot that burned was positively related to pre-fire grass height. Moreover, both grass height and the proportion of subplot burned declined in the burned subplots during the 6-year study period and fire and cattle grazing altered the relative cover of graminoids and shrubs (Rubus spp.), with more graminoids in grazed and/or burned subplots and more shrubs in ungrazed subplots at the end of the study. Synthesis and applications. In our temperate European wood pasture, fire and (cattle) grazing interacted in ways comparable to pyric herbivory in grassy ecosystems elsewhere in the world, especially in the most productive paddock. Fire attracted grazing, with cattle grazing longer on subplots that burned more fully. Grazing also affected fire, where over the course of our experiment cattle grazing reduced grass height and the proportion of a subplot that burned. We suggest that pyric herbivory is an interesting management method to further explore in the European context to address the loss of biodiversity in open ecosystems, particularly in more productive sites.In our temperate European wood pasture, fire and (cattle) grazing interacted in ways comparable to pyric herbivory in grassy ecosystems elsewhere in the world, especially in the most productive paddock. Fire attracted grazing, with cattle grazing longer on subplots that burned more fully. Grazing also affected fire, where over the course of our experiment cattle grazing reduced grass height and the proportion of a subplot that burned. We suggest that pyric herbivory is an interesting management method to further explore in the European context to address the loss of biodiversity in open ecosystems, particularly in more productive sites.image
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| 9. |
- Bergner, Adam, et al.
(författare)
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Influences of forest type and habitat structure on bird assemblagesof oak (Quercus spp.) and pine (Pinus spp.) stands in southwesternTurkey
- 2015
-
Ingår i: Forest Ecology and Management. - : Elsevier. - 0378-1127 .- 1872-7042. ; 336, s. 137-147
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Tidskriftsartikel (refereegranskat)abstract
- The Mediterranean basin exhibits a multitude of forest habitats affected by former and current exploitation and management. Recent afforestation programs have resulted in an increase in the proportion of coniferous trees, while oak stands, formerly utilized for coppicing and grazing, are abandoned or converted into coniferous plantations. The loss of oak stands might negatively affect birds dependent upon broadleaved forests. Studies confirming or rejecting that statement are scarce, particularly in the eastern part of the region. Using a study area in southwestern Turkey we applied a guild-based approach to investigate how pine and oak stands across a chronosequence differ in their capacity to support forest bird assemblages. Variables describing the vegetation were sampled to characterize the stands and relate bird assemblages to stand structure. Bird abundance and species richness was positively associated with age for both stand types. Richness and diversity was highest in oak stands, while there were no differences in bird abundance between the two forest types. Pine stands supported a different bird species composition compared to oak stands of the same age. Stand age and structure, rather than forest type, held the highest explanatory powers for bird assembly structure. Primary cavity-nesters and ground-nesters were more abundant in oak stands, possibly reflecting differences in stand structure and resource distribution. To support these birds with suitable habitats, oaks stands need conservation. Management practices in pine stands should strive for increasing the amount of old trees and retain vegetation in the understory to benefit breeding birds.
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| 10. |
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| 11. |
- Chantzi, Efthymia, et al.
(författare)
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COMBImage : a modular parallel processing framework for pairwise drug combination analysis that quantifies temporal changes in label-free video microscopy movies
- 2018
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Ingår i: BMC Bioinformatics. - : Springer Science and Business Media LLC. - 1471-2105. ; 19
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Tidskriftsartikel (refereegranskat)abstract
- Background: Large-scale pairwise drug combination analysis has lately gained momentum in drug discovery and development projects, mainly due to the employment of advanced experimental-computational pipelines. This is fortunate as drug combinations are often required for successful treatment of complex diseases. Furthermore, most new drugs cannot totally replace the current standard-of-care medication, but rather have to enter clinical use as add-on treatment. However, there is a clear deficiency of computational tools for label-free and temporal image-based drug combination analysis that go beyond the conventional but relatively uninformative end point measurements.Results: COMBImage is a fast, modular and instrument independent computational framework for in vitro pairwise drug combination analysis that quantifies temporal changes in label-free video microscopy movies. Jointly with automated analyses of temporal changes in cell morphology and confluence, it performs and displays conventional cell viability and synergy end point analyses. The image processing algorithms are parallelized using Google's MapReduce programming model and optimized with respect to method-specific tuning parameters. COMBImage is shown to process time-lapse microscopy movies from 384-well plates within minutes on a single quad core personal computer.This framework was employed in the context of an ongoing drug discovery and development project focused on glioblastoma multiforme; the most deadly form of brain cancer. Interesting add-on effects of two investigational cytotoxic compounds when combined with vorinostat were revealed on recently established clonal cultures of glioma-initiating cells from patient tumor samples. Therapeutic synergies, when normal astrocytes were used as a toxicity cell model, reinforced the pharmacological interest regarding their potential clinical use.Conclusions: COMBImage enables, for the first time, fast and optimized pairwise drug combination analyses of temporal changes in label-free video microscopy movies. Providing this jointly with conventional cell viability based end point analyses, it could help accelerating and guiding any drug discovery and development project, without use of cell labeling and the need to employ a particular live cell imaging instrument.
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| 12. |
- Chantzi, Efthymia, et al.
(författare)
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COMBImage2 : a parallel computational framework for higher-order drug combination analysis that includes automated plate design, matched filter based object counting and temporal data mining
- 2019
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Ingår i: BMC Bioinformatics. - : BMC. - 1471-2105. ; 20
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Pharmacological treatment of complex diseases using more than two drugs is commonplace in the clinic due to better efficacy, decreased toxicity and reduced risk for developing resistance. However, many of these higher-order treatments have not undergone any detailed preceding in vitro evaluation that could support their therapeutic potential and reveal disease related insights. Despite the increased medical need for discovery and development of higher-order drug combinations, very few reports from systematic large-scale studies along this direction exist. A major reason is lack of computational tools that enable automated design and analysis of exhaustive drug combination experiments, where all possible subsets among a panel of pre-selected drugs have to be evaluated.Results: Motivated by this, we developed COMBImage2, a parallel computational framework for higher-order drug combination analysis. COMBImage2 goes far beyond its predecessor COMBImage in many different ways. In particular, it offers automated 384-well plate design, as well as quality control that involves resampling statistics and inter-plate analyses. Moreover, it is equipped with a generic matched filter based object counting method that is currently designed for apoptotic-like cells. Furthermore, apart from higher-order synergy analyses, COMBImage2 introduces a novel data mining approach for identifying interesting temporal response patterns and disentangling higher- from lower- and single-drug effects.COMBImage2 was employed in the context of a small pilot study focused on the CUSP9v4 protocol, which is currently used in the clinic for treatment of recurrent glioblastoma. For the first time, all 246 possible combinations of order 4 or lower of the 9 single drugs consisting the CUSP9v4 cocktail, were evaluated on an in vitro clonal culture of glioma initiating cells.Conclusions: COMBImage2 is able to automatically design and robustly analyze exhaustive and in general higher-order drug combination experiments. Such a versatile video microscopy oriented framework is likely to enable, guide and accelerate systematic large-scale drug combination studies not only for cancer but also other diseases.
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| 13. |
- Christiansson, Rolf, et al.
(författare)
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Studier av sprängskador i Äspö-laboratoriet
- 2005
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Ingår i: Bergsprängningskommittén Diskussionsmöte BK 2005. - : Bergsprängningskommittén. ; , s. 139-152
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- En ny tunnel med 70 m längd byggdes på 450 m djup i Äspölaboratoriet 2003. Det ställdes speciella krav på begränsning av sprängskadezonens djup med hänsyn till planerade experiment.Tunneln drevs med galleri och bågformad låg pall för att minimera sprängskador i sulan. I huvuddelen av tunneln användes initieringsystemet Nonel MS och LP. I de tre sista salvorna av galleriet testades elektroniksprängkapslar. Skonsamhetsgraden för vägg och tak var normal med en tillåten skadezon på 0,3 m. Däremot tillämpades samma skonsamhetsgrad även för botten. I övrigt användes normal sprängteknik och normala sprängämnen som Dynotex 17 och Dynorex.Arbetet följdes noggrant genom dokumentation av utfört arbete. Vibrationsmätningar utfördes på nära håll samt på stort avstånd, 1,5 km från arbetsplatsen. Språng¬skador har undersökts genom sågning och sprickkartering.Föredraget kommer att presentera projektet, framförallt (1) erfarenheter från vibra¬tionsmätningar av samtliga sprängsalvor (noggrannheten i geofonmätningarna; totala antalet spränghål i salvorna; bomsalvor; avståndet från salvorna och geo¬logiska strukturer), (2) P-vågshastigheten i tunnelns närområde, (3) faktorer som påverkar utvecklingen av sprängskador, och (4) förslag på kontrollåtgärder som kan leda till att begränsa skadezonen i praktiskt tunnelarbete.
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| 14. |
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| 15. |
- Crawford, Elizabeth, et al.
(författare)
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Using Video Footage for Observing Honey Bee Behaviour at Hive Entrances
- 2022
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Ingår i: Bee world. - : Taylor & Francis Group. - 0005-772X .- 2376-7618. ; 99:4, s. 139-142
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Tidskriftsartikel (refereegranskat)abstract
- Video recording is a common method to study animal behaviour. In honey bee studies, short video-recordings are often used to learn more about a behaviour, but rarely used for their quantification. Standard methods for observing bee behaviour involve behavioural assays or direct observation of a limited subset of marked bees within an observation hive. This means that behaviour at the hive entrance may be overlooked. Here we describe a 4-camera set up for the study of behaviour at hive entrances. With minimal disturbance, we were able to record and quantify all previously described behaviours (9 in total - including self-grooming in drones) on and around the hive entrance. We briefly discuss the general feasibility of video footage and the relative frequency of each observed behaviour. Our conclusion is that video footage is a useful and perhaps overlooked method for unbiased quantification and comparisons of bee behaviour at the hive entrance. With this paper we are publishing some example short video-recordings as online supplementary material for educational purposes.
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| 16. |
- Drobyshev, Igor, et al.
(författare)
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A 700-year record of large fire years in northern Scandinavia shows large variability and increased frequency during the 1800s
- 2015
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Ingår i: Journal of Quaternary Science. - : Wiley. - 1099-1417 .- 0267-8179. ; 30:3, s. 211-221
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Tidskriftsartikel (refereegranskat)abstract
- Years with climatically mediated increases in boreal forest fire activity, referred to as large fire years (LFYs), contribute to a disproportionally large portion of the burned area over centuries, and are important drivers of ecosystem processes by affecting forest structure, biodiversity, and carbon balance at regional and continental scales. We analysed changes in LFY return intervals in northern Sweden (the area above 60°N) over 1273-1960 using a network of 29 sites with dendrochronologically reconstructed fires, complemented by documentary records of fires available from forestry statistics. We observed large variability in return intervals of LFYs, an increase in LFY frequency during the 1800s, and consistent associations between LFY occurrence and 500-hPa pressure anomalies over the European sub-continent over 1800xps2#1960. An increase in LFY frequency during the 1800s might be climatically driven, and would thus long precede the period of likely human-induced climatic changes of the 1900s. Long-term variability in climatically driven LFYs may present a challenge in partitioning the effects of human-related and human-independent components of climatic forcing upon forest fire activity. © 2015 John Wiley & Sons, Ltd.
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| 17. |
- Drobyshev, Igor, et al.
(författare)
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A mixture of human and climatic effects shapes the 250-year long fire history of a semi-natural pine dominated landscape of Northern Latvia
- 2019
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 441, s. 192-201
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Tidskriftsartikel (refereegranskat)abstract
- Fire has been shown to shape successional pathways and dynamics of forest vegetation. However, its role in European hemiboreal forests remains poorly understood. Here we provide the first annually resolved reconstruction of fire history from the Eastern Baltic Sea region, developed in the pine-dominated landscape of Slitere National Park (SNP), northwestern Latvia, over the last 250 years. Our results suggest that forest fires have been a common disturbance factor in the studied landscape. In total, we dated 62 single fire years, with the mean-point scale fire return interval of 46 years and the length of the fire cycle ranging from 45 to 80 years. We identified periods of high (1750-1950) and low (1960-2000) fire activity, with the corresponding lengths of fire cycles being 45-68 and 58-80 years, respectively. Although both long-term (century and decade-long) and annual dynamics of fire activity in SNP was closely linked to socio-political changes in Latvia, fire activity in SNP was also affected by climate, as indicated by the close positive association of years with increased area burned and positive SST anomalies in the Baltic and North Seas. Future management of SNP should make fire an important element of natural forest dynamics and consider using prescribed fires of various spatial extent and severity.
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| 18. |
- Drobyshev, Igor, et al.
(författare)
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Atlantic SSTs control regime shifts in forest fire activity of Northern Scandinavia
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the drivers of the boreal forest fire activity is challenging due to the complexity of the interactions driving fire regimes. We analyzed drivers of forest fire activity in Northern Scandinavia (above 60 N) by combining modern and proxy data over the Holocene. The results suggest that the cold climate in northern Scandinavia was generally characterized by dry conditions favourable to periods of regionally increased fire activity. We propose that the cold conditions over the northern North Atlantic, associated with low SSTs, expansion of sea ice cover, and the southward shift in the position of the subpolar gyre, redirect southward the precipitation over Scandinavia, associated with the westerlies. This dynamics strengthens high pressure systems over Scandinavia and results in increased regional fire activity. Our study reveals a previously undocumented teleconnection between large scale climate and ocean dynamics over the North Atlantic and regional boreal forest fire activity in Northern Scandinavia. Consistency of the pattern observed annually through millennium scales suggests that a strong link between Atlantic SST and fire activity on multiple temporal scales over the entire Holocene is relevant for understanding future fire activity across the European boreal zone.
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| 19. |
- Drobyshev, Igor, et al.
(författare)
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Did forest fires maintain mixed oak forests in southern Scandinavia? A dendrochronological speculation
- 2021
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 482
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Tidskriftsartikel (refereegranskat)abstract
- In northern Europe, a long history of human exploitation effectively eliminated legacies of natural disturbances in mixed oak forests and we currently lack understanding of the role of natural disturbance factors in affecting oak regeneration into the forest canopies. We compiled dendrochronological, observational and paleochronological data from Southern Sweden to discuss the role of forest fires in oak (Quercus spp.) dynamics. We analyzed oak age structure and its growth dynamics in six southern Swedish forests, which experienced fires between 42 and 158 years prior to our sampling. Extending our analysis over longer time frames, we studied the relationship between sediment charcoal and oak pollen in an area of south-eastern Sweden, where oak has been a common canopy species. In three of the study sites, forest fires resulted in increased oak regeneration. Although fires were generally not associated with a wave of growth releases in surviving trees, the mean basal area growth rate of oaks increased by a range of 108% to 176%, following the fires. The overall pattern indicated that historical fires in oak-dominated forests were of low severity, did not kill canopy oaks, and yet provided a window of regeneration opportunities for that species. Post-fire sprouting of oak and an increase in oak seedling densities following modern prescribed fires are consistent with this explanation. Consistent with this conclusion were significant positive correlations between charcoal concentration and the oak pollen percentage in a site in southeastern Sweden. We discuss the co-occurrence of oak and pine in the historical southern Swedish landscape, as a possible analogy to eastern North American oak-pine forests. Modern conservation policies aimed at the preservation of oak in the southern Swedish landscape should consider the use of low severity fires to maintain natural oak regeneration.
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| 20. |
- Drobyshev, Igor, et al.
(författare)
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Forest fire activity in Sweden: Climatic controls and geographical patterns in 20th century
- 2012
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923 .- 1873-2240. ; 154-155, s. 174-186
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Tidskriftsartikel (refereegranskat)abstract
- We used Swedish county-scale forest fire statistics to quantify modern fire activity, identify its main temporal and geographical patterns, and evaluate statistical performance of six fire-related weather indices as proxy of fire activity in Sweden over 1942–1975 and 1996–2008, the periods with available countyscale fire statistics. The analyzed indices were monthly precipitation, SPI, MDC, PDSI, calibrated PDSI, and DI, a Drought Index calculated as a ratio between actual and equilibrium evapotranspiration. The modern fire cycle (FC) in the northern part of Sweden varies between 2 × 103 and 3 × 104 years, whereas in southern Sweden the FC is somewhat shorter (103–2 × 104 years). No temporal trend in average FC was evident at the country scale between the two periods. Significant and negative values of a Mantel test, obtained on county data for both periods (r = −0.494, p = 0.001 for 1942–1975 and r = −0.281 and p = 0.015 for 1996–2008) indicated the presence of a geographical pattern in annual forest fire activity. Over 1942–1975, PCA revealed that the central and northern counties formed one group with synchronized fire activity, and the southern and south–western counties formed another group. This pattern became less evident during the more recent period (1996–2008). Over 1996–2008, the analysis showed little synchronicity in annual fire activity across different parts of the country. The geographical position of a county had a clear effect on seasonal pattern of forest fires. In southern Sweden, the peak in the number of fires and the burnt area was in April–May, during a relatively short dry period immediately following the snowmelt. In northern Sweden, fires in the second half of fire season dominated the total annual area burnt. Analyzed indices differed considerably in their predictive power in respect to counties’ records of annual area burnt. Calibrated PDSI was a superior proxy of fire activity for the southern region (R2 = 60.8% in regression against total annual area burnt for respective provinces), and DIlate (Drought Index for the first half of the growing season) was superior for the northern counties (R2 = 73.3%). Predictive power of the indices was much higher for the recent period (1996–2002), with R2 values staying within 81.2 and 97.8%. Even if modern levels of forest fire activity in Sweden are very low from historical perspective, there is a strong spatiotemporal association between fire activity and climatic variability at regional scales, which provides a basis for modeling of the future fire hazard.
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| 21. |
- Drobyshev, Igor, et al.
(författare)
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How old are the largest Southern Swedish oaks: a dendrochronological analysis
- 2010
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Ingår i: Broadleaved Forests in Southern Sweden: Management for Multiple Goals. - 9781405188869 ; 53:53, s. 155-163
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Bokkapitel (refereegranskat)abstract
- In the southern Scandinavian landscape, large oaks Quercus robur provide habitat for a wide range of species, including a large number species on the national Red list and the EU habitat directive. Since most of these trees are hollow and have likely been growing in conditions different from the ones of an “average” oak in today’s more forested landscape, direct inference of their age from diameter may be biased. To provide support for the management of these trees, we estimate their age by combining inventory data on diameter distribution of the largest oaks (n = 236) in the Swedish province of Scania and ring width distribution for large (> 1 m in stem diameter) oaks collected in seven oak-dominated stands (both woodland-type and denser closed-canopy forests) in southern Sweden (ntrees = 69, nrings = 12399). The mode of ring-width distribution was 1.26 mm /year. The central 90% of ring width distribution was within 0.54 and 3.38 mm, demonstrating the high growth plasticity of the species. Both ring width distribution in large oaks, divided into 16 width classes, and cumulative 20-yr diameter increments (19 classes) were well approximated by the log-normal function. The largest oaks in Scania are unlikely to exceed 1000 yr, the most probable age estimates of the majority of the inventoried oaks were centered around 500-700 yr. The age distribution of 18 large (69.4 - 178 cm dbh) non-hollow oaks suggesting the maximum age being around 400-600 yr. Conservation-oriented management of oak populations should address the need for preservation of such old trees
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| 22. |
- Drobyshev, Igor, et al.
(författare)
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Influence of annual weather on growth of pedunculate oak in southern Sweden
- 2008
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Ingår i: Annals of Forest Science. - : INRA, EDP Sciences. - 1286-4560 .- 1297-966X. ; 65:5, s. 512-512
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Tidskriftsartikel (refereegranskat)abstract
- A network of oak (Quercus robur L.) chronologies containing 49 sites and 635 single trees was analysed to identify weather variables affecting annual tree-ring increment dynamics in southern Sweden during 1860-2000. We analysed (1) the growth response of oak to non-extreme weather, and (2) the temporal and spatial patterns of regional growth anomalies (pointer years) and associated climatic extremes resolved on a monthly scale. Growth was controlled by precipitation in the current (June-July) and the previous growing season (August) in 48% and 22% of all sites, respectively. Temperature during July of the current year and August of the previous year was negatively correlated with growth in 29% and 43% of the sites, respectively. Growth was positively correlated with temperature in October of the previous season in 72% of the sites. The most extensive growth anomaly occured in 1965 and was probably caused by intrusion of cold Artic air masses into the region at the end of March that year. During the climatically non-extreme years, oak growth is driven mostly by the dynamics of summer precipitation. Many of the negative growth anomalies, however, were associated with temperature extremes. Southern Swedish oak pointer years tend not to coincide with the pan-European pointer years.
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| 23. |
- Drobyshev, Igor, et al.
(författare)
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Lifespan and mortality of old oaks - combining empirical and modelling approaches to support their management in Southern Sweden
- 2008
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Ingår i: Annals of Forest Science. - : Springer Science and Business Media LLC. - 1286-4560 .- 1297-966X. ; 65:4, s. 401-401
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Tidskriftsartikel (refereegranskat)abstract
- Old oaks (Quercus robur L.) play an important role in the southern Scandinavian landscape by providing habitat for a wide range of species, a large proportion of them being currently on the National Redlists. To provide support for the management of these trees, we review data on oak mortality and formulate a mortality-driven stochastic model analysing interactions between mortality rate, oak recruitment rate into 100-150 age class, and amount of oaks older than 200 years. Empirical annual mortality rates varied between 0 and 13% with average 1.68%. Trees older 200 years had an average mortality rate of 1.1%. Oaks in the high density forests showed higher mortality (3.2%) as compared to the trees growing in the low density forests (1.2%). A 400-year long modelling exercises indicated that under current mortality rates (regular mortality being centred around 1% annually; and irregular mortality 7% with average return time of 13 years) the long-term maintenance of 20 trees older than 200 years per ha would require an input rate of 1 to 5 trees x year(-1) x ha(-1) into the 100-150 years old class. The modelling highlighted the importance of initial oak abundance affecting amount of old trees at the end of shorter (100 years) simulation period.
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| 24. |
- Drobyshev, Igor, et al.
(författare)
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Marginal imprint of human land use upon fire history in a mire-dominated boreal landscape of the Veps Highland, North-West Russia
- 2022
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 507
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Tidskriftsartikel (refereegranskat)abstract
- Dendrochronological reconstructions inform us about historical climate-fire-human interactions, providing a means to calibrate projections of future fire hazard. Most of these reconstructions, however, have been developed in landscapes with a considerable proportion of xeric sites that could potentially inflate our estimates of the historic levels of fire activity. We provide a 420-year long reconstruction of fires in a mire-dominated landscape of the Veps Nature Park, North-West Russia. The area has mostly escaped large-scale forestry operations in the past and is an example of pristine mid-boreal vegetation with a high (approximately 30% for the area studied) proportion of waterlogged areas with ombrotropic mires. The historical fire cycle was 91.4 years (90% confidence intervals, CI 66.2-137.6 years) over the 1580-1720 period, decreasing to 35.9 (CI 28.1-47.6 years) between 1730 and 1770, and then increasing again to 122.7 years (CI 91.0-178.0 years) over the 1780-2000 period. Early season fires dominated over late season fires during the reconstruction period. We documented a higher fire activity period between 1730 and 1780, resulting from the increase in early season fires. This period coincided with one of the largest multi-decadal declines in the reconstructed spring precipitation since 1600 CE, although we found no significant relationship between fire and precipitation over the whole reconstructed period. The nine largest fire years were associated with negative summer precipitation and positive summer temperature anomalies over the study region. Land-use history of the area did not appear to have an effect on historical fire dynamics. Modern (1996-2016) fire records indicate a regional fire cycle of ~ 1300 years, featuring a pronounced pattern with early (April-May) and late (July-September) season fires. The uniform fire cycle in the area since 1780, occurrence of nine largest fire years during years with spring-summer droughts, and low ignition frequencies over the last 420 years (0.005 to 0.037 ignitions per year and km2) suggest that the fire regime of the Veps Highland remained largely natural until the onset of the 20th century.
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| 25. |
- Drobyshev, Igor, et al.
(författare)
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Masting behaviour and dendrochronology of European beech (Fagus sylvatica L.) in southern Sweden
- 2010
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 1872-7042 .- 0378-1127. ; 259:11, s. 2160-2171
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Tidskriftsartikel (refereegranskat)abstract
- To identify weather controls of beech diameter growth and masting in southern Sweden, we analyze records of monthly weather, regional masting record, and tree-ring chronologies from five beech-dominated stands. The results indicate a strong weather control of temporal pattern of masting events in southern Sweden over the second half of the 20th century. Negative summer temperature anomaly 2 years prior to a mast year, coupled with positive temperature anomaly in the year immediately preceding the same mast year, is a characteristic weather pattern associated with known mast years. Strong dependence of beech masting behavior on temperature explains the high degree of regional synchronization of masting events. Growth of beech in southern Sweden is strongly and negatively correlated with previous year's summer temperature and positively - with previous year's October temperature. The present study does not provide a conclusive answer in identifying a full set of direct and indirect effects of climatic variables controlling tree-ring growth, since the negative effect of previous year's summer temperature may be a result of a temperature-controlled increase in the beech nut production in the current year. Consistent and significant negative departures of ring-width index during mast years support the hypothesis about a trade-off between investment of bioassimilates into production of beech nuts and tree-ring growth. Alternative explanation of growth anomalies in mast years, relating such anomaly to a negative impact of previous year's growing season, was not supported by the data. We found a limited effect of masting on diameter growth in the following years, indicating that decline in the overall wood production, associated with heavy masting, is short term and typically occurs in the year of actual masting. (C) 2010 Elsevier B.V. All rights reserved.
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| 26. |
- Drobyshev, Igor, et al.
(författare)
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Multi-century reconstruction of fire activity in Northern European boreal forest suggests differences in regional fire regimes and their sensitivity to climate
- 2014
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 102:3, s. 738-748
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Tidskriftsartikel (refereegranskat)abstract
- Forest fires are one of the main disturbance agents in boreal and temperate ecosystems. To decipher large-scale temporal and spatial patterns of past fire activity in Scandinavia, we analysed the synchronicity of dendrochoronologically reconstructed fire events in a large network of sites (n=62; 3296 samples, 392 individual fire years) covering a wide geographical gradient (56.5-67.0 degrees N and 9.3-20.5 degrees E) over AD 1400-1900. We identified large fire years (LFY) as years with regionally increased forest fire activity and located the geographical centres of climatic anomalies associated with synchronous LFY occurrence across the region, termed LFY centroids. The spatial pattern of LFY centroids indicated the presence of two regions with climatically mediated synchronicity of fire occurrence, located south and north from 60 degrees N. The return intervals of LFYs in Scandinavia followed a Weibull distribution in both regions. Intervals, however, differed: a period of 40years would carry a 0.93 probability of LFY occurrence in the southern region, but only a 0.48 probability of LFY occurrence in the northern region. Over 1420-1759, the northern region was characterized by significantly higher temporal variability in LFY occurrence than the southern region. Temporal correlation of LFYs with reconstructed average summer temperature and total precipitation was evident mainly for the northern region. LFYs in this region were associated with positive temperature and negative precipitation anomalies over Scandinavia and with colder and wetter conditions in more southern parts of the European subcontinent. Synthesis. Historical patterns of the occurrence of large fire years (LFY) in Scandinavia point towards the presence of two well-defined zones with characteristic fire activity, with the geographical division at approximately 60 degrees N. The northern and mid-boreal forests, although exhibiting lower LFY frequencies, appeared to be more sensitive to past summer climate, as compared to the southern boreal forests. This would imply that fire regimes across Scandinavia may show an asynchronous response to future climate changes.
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| 27. |
- Drobyshev, Igor, et al.
(författare)
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Reconstruction of a 253-year long mast record of European beech reveals its association with large scale temperature variability and no long-term trend in mast frequencies
- 2014
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Ingår i: Agricultural and Forest Meteorology. - : Elsevier BV. - 0168-1923 .- 1873-2240. ; 192, s. 9-17
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Tidskriftsartikel (refereegranskat)abstract
- Synchronous production of large seed crops, or mast years (MYs), is a common feature of many Fagus species, which is closely linked to the dynamics of forest ecosystems, including regeneration of canopy trees and changes in animal population densities. To better understand its climatic controls and check for the presence of long-term temporal trends in MY frequencies, we reconstructed MY record of the European beech (Fagus sylvatica L.) for the southern Swedish province of Halland over 1753-2006. We used superimposed epoch analysis (SEA) to relate MY (a) to summer temperature fields over the European subcontinent and (b) to the patterns of 500 mb geopotential heights over the 35-75 degrees N. For the MY reconstruction, we used newly developed regional beech ring-width chronology (1753-2006), an available summer temperature reconstruction, and a discontinuous historical MY record. A Monte Carlo experiment allowed identification of the thresholds in both growth and summer temperature anomalies, indicative of historical MYs, which were verified by dividing data into temporally independent calibration and verification sub-periods.MYs were strongly associated with both the 500 mb height anomalies and average summer temperatures during two years preceding a MY: a mast year (t) followed a cold summer two years (t-2) prior to the mast year and a warm summer one year prior (t-1) to the mast year. During t-2 years, the geographical pattern of 500 mb height anomalies exhibited a strong height depression in the region centered in the Northern Sea and extending toward eastern North America and statistically significant (p<0.05) temperature anomalies covering predominantly southern Scandinavia (area below 60 N) and British Isles. A year immediately preceding a mast year (t-1) was characterized by a strong regional high pressure anomaly centered in southern Scandinavia with significant temperature anomalies extended mostly over southern Scandinavia and Germany.The long-term mean MY return interval was 6.3 years, with 50 and 90% probabilities of MY occurrence corresponding to 6 and 15 years, respectively. Periods with intervals significantly shorter than the long-term mean were observed around 1820-1860 and 1990-2006 (means 3.9 and 3.2 years, respectively). However, the difference in return intervals between two sub-periods themselves was not significant.Geographically large and temporally rapid changes in atmospheric circulation among years, responsible for summer temperature conditions in the Northern Europe, are likely primary environmental drivers of masting phenomenon. However, decadal and centurial variability in MY intervals is difficult to relate directly to temperature variability, suggesting the presence of conditions "canceling" would-be MYs. Long-term MY reconstruction demonstrates high variability of reproductive behavior in European beech and indicates that a period with shorter MY intervals at the end of 20th may be not unique in a multi-century perspective. (C) 2014 Elsevier B.V. All rights reserved.
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| 28. |
- Drobyshev, Igor, et al.
(författare)
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Reconstruction of a regional drought index in southern Sweden since AD 1750
- 2011
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 21:4, s. 667-679
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Tidskriftsartikel (refereegranskat)abstract
- We used a network of eight pedunculate oak (Quercus robur L.) sites (n(trees) = 70) and one Scots pine (Pinus sylvestris L.) site (n(trees) = 53) to develop drought-sensitive master chronologies for the two areas in southern Scandinavia: a SW-area centred on 57AN 12.7AE and a NE-area centred on 58.8AN 18.2AE. The ratio of actual to equilibrium evapotranspiration (AET/EET) was used as a measure of drought during the growing season defined as the period with average daily temperatures above 9 degrees C. Instrumental data were used to parameterize the relationship between tree-ring data and the drought index (DI) over 1922-2000 for the SW area and over 1922-1995 for the NE area. The DI reconstructions explained 29.7% (SW area) and 43.7% (NE area) of the variance in the observed DI index in the calibration period, and were extended back to AD 1770 for the SW area and to AD 1750 for the NE area. Reconstructed drought dynamics suggested strong decadal- and century-scale temporal variability and limited regional synchronicity over 1770-2000. Large variations in DI were observed in both regions in the second half of the 1700s. Dry conditions were synchronously reconstructed in both sub-regions during 1781-1784, 1853-1855, and, to a lesser degree, during 1974-1978. Over the 1945-1975 period the SW area exhibited a trend towards drier growing seasons, whereas no such trend could be identified for the NE area. Analysis of correlation maps indicated that regional DI dynamics reflected two different climate regimes, associated with the Kattegat area (SW reconstruction) and southeastern Swedish coast of the Baltic sea (NE reconstruction).
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| 29. |
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| 30. |
- Felton, Adam, et al.
(författare)
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Replacing monocultures with mixed-species : Ecosystem service implications of two production forest alternatives in Sweden
- 2016
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 45:Suppl. 2, s. 124-139
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Tidskriftsartikel (refereegranskat)abstract
- Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Picea abies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinus sylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures.
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| 31. |
- Felton, Adam, et al.
(författare)
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Replacing monocultures with mixed-species stands : Ecosystem service implications of two production forest alternatives in Sweden
- 2016
-
Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 45, s. 124-139
-
Tidskriftsartikel (refereegranskat)abstract
- Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Picea abies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinus sylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures.
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| 32. |
- Fritz, Örjan, et al.
(författare)
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Bjurkärr – en småländsk bokskog med unika lavar och svampar.
- 2014
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Ingår i: Svensk Botanisk Tidskrift. - 0039-646X. ; 108:3–4, s. 2-18
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Tidskriftsartikel (refereegranskat)abstract
- The old beech forest (250–300 yr) at Bjurkärr (core area 30 ha) in the province of Småland, S Sweden, was surveyed for epiphytic lichens of conservation concern in 1993–94. Several rare red-listed lichens were recorded, many with large populations. In 2011 the most endangered lichens were resurveyed due to the incorporation of Bjurkärr in the forthcoming national park of Lake Åsnen. Most species of the 1993–94 survey were rediscovered, whereas some apparently had vanished as a result of substrate decomposition. In addition, ten more red-listed lichens were recorded in 2011, e.g., Arthonia arthonioides and Collema fragrans. We also recorded Biatora ligni-mollis, not previously reported from Sweden. In all, 39 red-listed lichens are currently known from the area. Few areas in Sweden host such a large number of red-listed epiphytic lichens. In addition, the wood-inhabiting fungi on beech logs and snags were surveyed in 2011. The content of dead wood was high. A large number of red-listed or otherwise interesting wood-inhabiting fungi were recorded, e.g., Hericium erinaceus. Eleven fungal indicator species for valuable beech forests in Europe were recorded, the highest number for any Swedish beech forest. Factors explaining the high number of species of conservation concern include the long continuity of old, often slow-growing and damaged trees, the favourable geographical position in south Sweden, the suitable microclimate caused by the large neighboring lake and the exemption from modern forestry.
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| 33. |
- Fritz, Örjan, et al.
(författare)
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Tree age is a key factor for the conservation of epiphytic lichens and bryophytes in beech forests
- 2009
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Ingår i: Applied Vegetation Science. - 1402-2001. ; 12, s. 93-106
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Tidskriftsartikel (refereegranskat)abstract
- Questions: What factors limit the distribution of epiphytic lichens and bryophytes at plot and tree level in beech forests? At what ages do epiphytic species, and species of conservation concern in particular, occur along a chronosequence of beech?Location: South-west Sweden.Method: Five hundred and seventy-one age-determined trees from 37 plots distributed among 29 beech-dominated stands were Surveyed along with a number of environmental (16) and substrate (seven) variables in a landscape of ca. 550ha. Non-metric multidimensional scaling (NMS) and indicator species analysis (ISA) were used for data analysis.Results: Plots containing old trees, confined to the base of slopes and with low impacts of recent forestry (thinning), generally had a high richness of species of conservation concern. Richness of common species and red-listed bryophytes were mostly related to the surveyed bark area. At tree level, primary factors explaining both species richness and composition were age, diameter at breast height and moss cover. There was a gradual replacement of tree age ranges for 58 lichens and 37 bryophytes along the chronosequence of beech. Red-listed lichens favoured damaged beech trees ( >= 180 years), whereas red-listed bryophytes were found on old and young steins in dense stands.Conclusions: Tree age exerts a profound influence on epiphytic lichens and bryophytes growing on beech. Many of the habitat specialists were found mainly on old beech because they inhabit specific substrates that occur on older trees. The association to high tree age commonly excludes red-listed lichens from conventionally managed beech forests with a 100- to 140-year rotation period.
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| 34. |
- Fröberg, Lars, et al.
(författare)
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Age and epiphytic lichen diversity of the dwarf shrub Helianthemum oelandicum on the island of Öland , Sweden
- 2009
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Ingår i: The Lichenologist. - : British Lichen Society. - 0024-2829 .- 1096-1135. ; 41:5, s. 537-545
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Tidskriftsartikel (refereegranskat)abstract
- Lichen cover and diversity was analysed on the dwarf shrub Helianthemum oelandicum (L.) Dum.Cours.at one site in the calcareous grassland of the area known as the 'Great Alvar' on the Island of Öland, Sweden. The age of 22 phorophytes was determined by ring counting and varied from 8 to 41 years and was accurately predicted by the root diameter. A total of 18 lichen species were found, with a range between 0 and 13 species per phorophyte. The number of lichen species on living H. oelandicum was correlated with the phorophyte age. The number of lichen species and their coverage was greater on dead compared with living phorophytes. The species number was also higher on thin branches compared with thick branches and roots and some of the species showed preferences for dead phorophytes, and for thin branches. This study of lichen colonization and growth on dwarf shrubs in relation to phorophyte age is a new application of herbchronology.
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| 35. |
- Gillberg, Christopher, 1950, et al.
(författare)
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Co-existing disorders in ADHD -- implications for diagnosis and intervention.
- 2004
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Ingår i: European Child & Adolescent Psychiatry. - : Springer Science and Business Media LLC. - 1018-8827 .- 1435-165X. ; 13 Suppl 1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: It is only recently that "comorbidity" in ADHD has come to the forefront as one of the most important aspects of the disorder. It is agreed that, often, these problems are at least as important as ADHD in contributing to the longer term outcome in the individual child. OBJECTIVE: To provide the reader with basic information about clinics and treatment of "comorbidity" in ADHD. METHOD: Review of the empirically based literature. RESULTS: ADHD exists in a surprisingly high frequency together with a broad range of child neuropsychiatric disorders. This is accompanied with many still unresolved treatment problems. CONCLUSION: It would not be appropriate to develop ADHD-services where clinicians would only have expertise in ADHD as such. Anyone working with children, adolescents and adults with ADHD would need to have training in general neuropsychiatry. Further research in this field is urgently needed.
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| 36. |
- Granström, Anders, et al.
(författare)
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En brandhistorisk analys av Rossenområdet i västra Hälsingland
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Länsstyrelsen gav 2003 Anders Granström, universitetslektor vid institutionen för skoglig vegetationsekologi vid SLU i Umeå, och Mats Niklasson, forskare vid institutionen för sydsvensk skogsvetenskap på SLU i Alnarp, i uppdrag att göra en detaljerad analys av brandhistoriken i Rossenområdet. Det är ett cirka 1000 hektar stort talldominerat skogsområde väster om sjön Rossen i Ljusdals kommun. Den generella bild som träder fram för Rossenområdet är en brandregim med relativt täta bränder, som vanligen varit av så pass låg intensitet att trädskiktet av äldre tall överlevt, medan klenare ungtall samt gran dödats. Nu och då har elden dödat även bland äldre tall. Detta har antagligen skett på en skala från mindre fläckar upp till områden av flera hektar. De exakta mönstren är svåra att belägga, men de två mer koncentrerade provtagningarna som vi gjorde indikerar att nyrekrytering inom bestånden huvudsakligen har följt på de bränder som verkligen dödat i kronskiktet, och att det då inte rört sig om enstaka träd utan grupper. Det är troligt att bland annat topografin inverkat på denna storskaliga skogsstruktur. Inom delar av området var det mycket svårt att hitta riktigt gammalt (pre-1600) vedmaterial. Det gäller främst områdena väster och norr om Klimparna, där det är sannolikt att en brand under 1600-talet dödade på bred front. Områden med bruten topografi och inslag av myrmarker och öppet vatten har ofta ett större inslag av multipelt ljudad tall, troligen en följd av att brandfronten i sådana områden tenderar att brytas upp, med åtföljande sänkning av brandintensiteten (Granström opublicerat). Brandintervallen har varit korta, med ett medel av bara 40 år! En mycket stor del av bränderna har inträffat så pass kort tid efter föregående brand att bränslebädden inte varit fullt återställd (Schimmel & Granström 1997). Detta bör ha bidragit till den generellt låga brandintensiteten. Även i ett nationellt perspektiv är brandintervallen i Rossenområdet korta; väsentligt kortare än i Norra Norrlands inland och snarast i paritet med delar av Sydsveriges skogsbygder. Likaså inträder det obligatoriska brandavslutet tidigt i Rossen. En gradvis minskning av antalet bränder sker redan under slutet av 1700-talet och processen fullbordas före 1850. Det är några decennier tidigare än i övre Norrland och liknar återigen snarast situationen i södra Sverige (Niklasson opublicerat).
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| 37. |
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| 38. |
- Ji, Yu-Xia, et al.
(författare)
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Thermochromic VO2 films by thermal oxidation of vanadium in SO2
- 2016
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Ingår i: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 144, s. 713-716
-
Tidskriftsartikel (refereegranskat)abstract
- Thermochromic films of VO2 were prepared by a two-step procedure: Sputtering was first used to deposit metallic vanadium, and such layers were subsequently oxidized in SO2 at a temperature in the 600-650 degrees C range. X-ray diffraction, Raman spectroscopy, measurements of temperature-dependent electrical resistance, and spectrophotometric transmittance data at different temperatures were employed to demonstrate that the films consisted of polycrystalline VO2 with good thermochromism, especially when oxidized at the highest temperature. Oxidation in SO2 is able to produce VO2 without the stringent process control that can be an obstacle for making VO2 by oxidation in O-2.
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| 39. |
- Johansson, Malin B, 1972-, et al.
(författare)
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Porous Fractals of MAPbI3 Perovskite : Characterization of Crystal Grain Formation by Irreversible Diffusion-Limited Aggregation
- 2018
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Konferensbidrag (refereegranskat)abstract
- Isopropanol solution based methylammonium lead triiodide (MAPbI3) is studied during the crystallization process. The crystal growth starts in an unstable suspension far from equilibrium by forming different dendritic patterns and terminates with aggregation of stable cubic crystalline grains into fractal clusters. Using transmission electron microscopy (TEM), the time evolution of a newly mixed suspension was studied over a period of two weeks at room temperature and a sequence of the morphological changes was observed. The crystallization process started with single dendritic growth exhibiting branches at 90 degrees angles to one another. After 4 hours, a multi-dendritic growth pattern and a transformation into small crystalline quantum dots were observed. After a week, clusters of crystal grains were formed into a fractal pattern and these patterns appear to be stable also during the second week. Electron and x-ray diffraction revealed the crystallinity of the quantum dots and the clusters of micrometer-sized crystals. Scanning transmission electron microscope (STEM) together with energy dispersive X-ray spectroscopy (EDS) showed that newly formed large grains, from a one hour old solution, displayed a core-shell structure with higher percentage of Pb atoms as compared to iodine at the surface. In the inner core of the grains the percentage of iodine was slightly higher. The electron diffraction (ED) scan over the newly formed grains revealed a polycrystalline surface whereas the inner part had a single crystal pattern. The same solution, now one-week-old, contained grains with only single crystal patterns in the ED scan and showed no core-shell character or polycrystalline surface. The measured percentage of iodine atoms compared to lead was 2:1 throughout the cross section, which is a quantitative value within the measurement. It can be concluded from these measurements that the suspension approaches higher crystallinity of the perovskite grains in an irreversible process, where the perovskite grains are insoluble in isopropanol. The perovskite material has also been characterized with scanning electron microscopy (SEM) and photoluminescence (PL) mapping where both techniques showed a very porous crystalline material. The PL mapping revealed two peaks at 730 and 760 nm for a thin film spin coated from a newly mixed solution, while a film deposited from a one week old solution showed three peaks, the last one at 830 nm. Because of the high crystallinity, it is suggested that all three peaks are due to band-to-band transitions and not due to localized states. These data will be analyzed further; however, the results contain information of the content of quantum dots versus larger crystals, as well as displaying emission intensity variations at different positions of the grains. The purpose with this project is to understand these phenomena of crystal growth. A new mesoporous perovskite material has been designed for optoelectronic purposes.
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- Leidenberger, Sonja, et al.
(författare)
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Nordiskt honungsbi studeras på Nordens ark
- 2019
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Ingår i: Yrfän. - : Sveriges entomologiska förening. - 2002-1151. ; :3, s. 22-25
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Tidskriftsartikel (populärvet., debatt m.m.)
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- Leidenberger, Sonja, et al.
(författare)
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Vetenskapliga studier av honungsbin
- 2022
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Ingår i: Fauna och flora. - : Naturcentrum AB. - 0014-8903. ; 117:2, s. 28-32
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 48. |
- Lindbladh, Matts, et al.
(författare)
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Long-time record of fire and open canopy in a high biodiversity forest in southeast Sweden
- 2003
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Ingår i: Biological Conservation. - 1873-2917. ; 114:2, s. 231-243
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Tidskriftsartikel (refereegranskat)abstract
- We studied a ca 200 ha large forest site that holds an exceptionally large number of red-listed saproxylic beetles. We conducted pollen, charcoal and dendroecological analyses to reveal the long-term stand-level history of the site. We also investigated which of the red-listed saproxylic beetles recorded at the site are probably dependent on forest fires or structures that are created by fires. Pollen from Pinus and Betula dominate the pollen diagram, and the pollen record shows that the canopy is more closed today than ever during the last 2500 years. Large amounts of charcoal fragments were found throughout the core except during three shorter periods, one of which is the latest ca 200 years. The dendroecological investigation revealed I I different fires, the earliest dated to AD 1586 and the last dated to AD 1868. Of the 105 red-listed saproxylic beetles recorded at the site, at least 12 are associated with open forests with Pinus sylvestris or Birch spp. trees. We conclude that the fires, as recorded both by the charcoal and dendroecological analysis, kept the site largely open in the past, and this is likely one important explanation for the high conservation value of the site today. Other important factors could be that the site is rich in boulders, the relatively warm summer climate in the region, that Picea abies has not been planted in the surroundings until recently, and finally the presence of many old trees. The study supports the theory that fire could have been an important factor for keeping some forest types open before the large human impact on the northwestern European forests started.
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| 49. |
- Menkis, Audrius, et al.
(författare)
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Endophytes dominate fungal communities in six-year-old veteranisation wounds in living oak trunks
- 2022
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Ingår i: Fungal Ecology. - : Elsevier BV. - 1754-5048 .- 1878-0083. ; 59
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Tidskriftsartikel (refereegranskat)abstract
- Old trees are rare in the landscape, as are many of their associated species. Veteranisation is a method by which attempts are made to create microhabitats, otherwise found only in old trees, in younger trees at an earlier stage than would occur naturally. Here, we analysed the early fungal succession in 6 y-old veteranisation wounds in ca. 100 y old living oak trunks by DNA-barcoding of the wood at eight sites in Sweden and Norway. We hypothesised basidiomycetes would be most abundant, and exposed sapwood and heartwood would select for different communities. We identified 686 fungal taxa, mainly ascomycetes, with a large overlap in species composition and surprisingly similar species richness, i.e. 325 vs. 308–360, between intact and different types of damaged wood, respectively. Endophytes continued to be present and common in damaged wood. The results demonstrate that damage to sapwood and heartwood partly select for different fungi and that 6 y is too early to evaluate if veteranisation can positively favour fungi of conservation interest.
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