| 1. |
- Arnell, Matilda, 1987-, et al.
(författare)
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Reproductive success, fruit removal and local distribution patterns in the early-flowering shrub Daphne mezereum
- 2023
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Ingår i: Nordic Journal of Botany. - 0107-055X .- 1756-1051. ; :10
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Tidskriftsartikel (refereegranskat)abstract
- In insect-pollinated, bird-dispersed plants, both investment in reproduction and reproductive success involve interactions between plants and their pollinators and dispersers. The outcome of these plant–animal interactions may be affected by the number of flowers and fruits, as well as by the plants' local environment and by spatial associations among plants. In this study we mapped the spatial distribution of individuals in a population of the early flowering, fleshy-fruited shrub Daphne mezereum, in a forest in boreo-nemoral Sweden. For all mapped individuals we collected data on numbers of flowers and fruits and fruit removal, for three consecutive years. We analysed spatial associations among individuals, and the effects on reproductive performance and fruit removal of plant height, numbers of flowers and fruits, distance to forest edge, and neighbouring flower and fruit density. Our results show that the density of D. mezereum increases with increasing proximity to forest edge. The number of flowers produced, as well as fruit set and fruit removal, show the same positive relationship with increasing proximity to forest edges. We further show that individuals are aggregated up to distances of about 10 m. The flower production of neighbouring conspecific individuals within 10 m is negatively related to fruit set whereas the fruit production of neighbours is positively related to fruit removal. Our main conclusion is that the spatial distribution of D. mezereum affects reproductive success and fruit removal, which in turn has the potential to feed back to the spatial distribution pattern. Combining studies of reproduction with spatial analyses is important to advance our understanding of the dynamics of plant populations.
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| 2. |
- De Schuyter, Wim, et al.
(författare)
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Declining potential nectar production of the herb layer in temperate forests under global change
- 2024
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Ingår i: Journal of Ecology. - 0022-0477 .- 1365-2745. ; 112:4, s. 832-847
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Tidskriftsartikel (refereegranskat)abstract
- Wild pollinators are crucial for ecosystem functioning and human food production and often rely on floral resources provided by different (semi-) natural ecosystems for survival. Yet, the role of European forests, and especially the European forest herb layer, as a potential provider of floral resources for pollinators has scarcely been quantified.In this study, we measured the potential nectar production (PNP) of the forest herb layer using resurvey data across 3326 plots in temperate forests in Europe, with an average time interval of 41 years between both surveys in order to assess (i) the importance of the forest herb layer in providing nectar for wild pollinators, (ii) the intra-annual variation of PNP, (iii) the overall change in PNP between survey periods and (iv) the change in intra-annual variation of PNP between survey periods. The PNP estimates nectar availability based on the relative cover of different plant species in the forest herb layer. Although PNP overestimates actual nectar production, relative differences amongst plots provide a valid and informative way to analyse differences across time and space.Our results show that the forest herb layer has a large potential for providing nectar for wild pollinator communities, which is greatest in spring, with an average PNP of almost 16 g sugar/m2/year. However, this potential has drastically declined (mean plot-level decline >24%).Change in light availability, associated with shifts in canopy structure and canopy composition, is the key driver of temporal PNP changes.Synthesis. Our study shows that if management activities are carefully planned to sustain nectar-producing plant species for wild pollinators, European forest herb layers and European forests as a whole can play key roles in sustaining wild pollinator populations.
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| 3. |
- Eriksson, Ove, 1956-, et al.
(författare)
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Concepts for Integrated Research in Historical Ecology
- 2018
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Ingår i: Issues and Concepts in Historical Ecology: ThePast and Future of Landscapes and regions. - Cambridge : Cambridge University Press. - 9781108420983 - 9781108355780 ; , s. 145-181
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Bokkapitel (refereegranskat)
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| 4. |
- Eriksson, Ove, 1956-
(författare)
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Domesticated Forest Landscapes in Central Scandinavia during the Iron Age : Resource Colonization for Iron and Subsistence Strategies based on Livestock
- 2023
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Ingår i: Journal of field archaeology. - : Informa UK Limited. - 0093-4690 .- 2042-4582. ; 48:4, s. 315-326
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Tidskriftsartikel (refereegranskat)abstract
- This study explores how resource colonization for iron in central Sweden during the early Iron Age may have affected the use of forest landscapes. Slag heap volume at iron production sites was used to estimate the amount of forest resources required for charcoal production. Forest resources required for livestock grazing and fodder were estimated from literature sources. To produce charcoal at iron production sites, forests were harvested, creating conditions suitable for grazing. Production of livestock winter fodder, leaf-hay, became a constraint due to the conflict between grazing grounds and fodder producing areas near main settlements. Although availability of forest was not limiting, a combination of opportunities and constraints is suggested to have promoted a new spatial ordering of land use. This included land closest to the main settlements allocated to fodder production and development of secondary seasonal settlements (shielings) at iron production sites, which could be exploited for livestock grazing.
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| 5. |
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| 6. |
- Eriksson, Ove, 1956-
(författare)
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The power of observation : Eugen Warming (1918) Om Jordudløbere (‘Underground runners') and the ecology and evolution of clonal plants
- 2023
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Ingår i: Nordic Journal of Botany. - 0107-055X .- 1756-1051. ; 2023:7
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Forskningsöversikt (refereegranskat)abstract
- Although often overlooked, the Danish botanist Eugen Warming was one the founders of ecology as a science. He also wrote extensively on plant life forms, including an essay from 1918, Om Jordudløbere (‘Underground runners'), which specifically focused on clonal plants. As was common among naturalists during the 19th century, Warming was exceptionally skillful in drawing conclusions from plain observation. The present paper examines how Warming understood and interpreted the ecology and evolution of clonal plants, and compares his insights with those emanating during the revival of research on clonal plants from the late 1970s onward. Several of the key topics in this revival were treated already by Warming, particularly clonal plants' ability of mobility by horizontal growth, the features affecting the ‘splitting' of genets into independent ramets, and how clonal life forms evolve. Despite these thematic similarities, Warming's direct impact on later research was limited, with the possible exception of the concept of plant functional types. This does not preclude that Warming's insights have bearing on the current research agenda on the ecology and evolution of clonal plants. The paper ends with a brief discussion of horizontal growth as a means to extend genet lifespan, thereby providing a basis for evolution of clonal plant life form through processes acting within genets.
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| 7. |
- Johansson, Karl-Axel, et al.
(författare)
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The quality assurance process for the ARTSCAN head and neck study - a practical interactive approach for QA in 3DCRT and IMRT.
- 2008
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Ingår i: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 87:2, s. 290-9
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Tidskriftsartikel (refereegranskat)abstract
- AIM: This paper describes the quality assurance (QA) work performed in the Swedish multicenter ARTSCAN (Accelerated RadioTherapy of Squamous cell CArcinomas in the head and Neck) trial to guarantee high quality in a multicenter study which involved modern radiotherapy such as 3DCRT or IMRT. MATERIALS AND METHODS: The study was closed in June 2006 with 750 randomised patients. Radiation therapy-related data for every patient were sent by each participating centre to the QA office where all trial data were reviewed, analysed and stored. In case of any deviation from the protocol, an interactive process was started between the QA office and the local responsible clinician and/or physicist to increase the compliance to the protocol for future randomised patients. Meetings and workshops were held on a regular basis for discussions on various trial-related issues and for the QA office to report on updated results. RESULTS AND DISCUSSION: This review covers the 734 patients out of a total of 750 who had entered the study. Deviations early in the study were corrected so that the overall compliance to the protocol was very high. There were only negligible variations in doses and dose distributions to target volumes for each specific site and stage. The quality of the treatments was high. Furthermore, an extensive database of treatment parameters was accumulated for future dose-volume vs. endpoint evaluations. CONCLUSIONS: This comprehensive QA programme increased the probability to draw firm conclusions from our study and may serve as a concept for QA work in future radiotherapy trials where comparatively small effects are searched for in a heterogeneous tumour population.
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| 8. |
- Larsén, Eva, 1980-
(författare)
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Phylogeny and macroevolution in Isoetes (Isoetales)
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis has focused on the evolutionary history of Isoetes (Isoetales, Lycopsida), its phylogeny, megaspore morphology and evolutionary path through deep time. With a broadened sampling of species to include more of the worldwide diversity of the genus compared to previous work an unexpected sister to the rest of the genus was found. Isoetes wormaldii Sim is a critically endangered species from the southeastern Cape region in South Africa, which grows in ponds and slow-moving streams. There are only a few, small populations, and they are very sensitive to habitat changes. The rest of Isoetes is divided into five major clades, which show complex and not readily understandable biogeographic patterns, and by which processes the species came to live in their current locations in the world is often a conundrum. The age of the extant Isoetes is intriguing as it could potentially explain some of the baffling geographic distributions. Analyses based on whole chloroplast genomes and nuclear cistrons found that the choice of clock model and which genome dataset the dating analysis is based on matter greatly when trying to date the genus as the results were highly inconsistent. The solution to the dating analysis woes might be dependent on finding new bases, e.g., fossil evidence, for age calibrations which would require the morphology of Isoetes to be better understood. Our study of megaspore morphology found substantial differences among species of Isoetes in both ornamentation and surface texture/structure. While no major clade within the genus could be unambiguously defined by their spore morphology there are some characteristics of smaller clades and patterns of ornamentation and surface texture across the phylogeny. Our tentative hypothesis is that a pustulate megaspore ornamentation and a cobwebby texture are ancestral features in the megaspore of Isoetes.
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| 9. |
- Zackrisson, Björn, et al.
(författare)
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Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma - The ARTSCAN study
- 2011
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Ingår i: Radiotherapy and Oncology. - : Elsevier. - 0167-8140 .- 1879-0887. ; 100:1, s. 41-48
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: Studies on accelerated fractionation (AF) in head and neck cancer have shown increased local control and survival compared with conventional fractionation (CF), while others have been non-conclusive. In 1998 a national Swedish group decided to perform a randomised controlled clinical study of AF. Materials and methods: Patients with verified squamous cell carcinoma of the oral cavity, oropharynx, larynx (except glottic T1-T2, N0) and hypopharynx were included. Patients with prior chemotherapy or surgery were excluded. Patients were randomised to either CF (2Gy/day, 5days/week for 7 weeks, total dose 68Gy) or to AF (1.1Gy+2.0Gy/day, 5days/week for 4.5weeks, total dose 68Gy). An extensive quality assurance protocol was followed throughout the study. The primary end point was loco-regional tumour control (LRC) at two years after treatment. RESULTS: The study was closed in 2006 when 750 patients had been randomised. Eighty-three percent of the patients had stages III-IV disease. Forty eight percent had oropharyngeal, 21% laryngeal, 17% hypopharyngeal and 14% oral cancers. There were no significant differences regarding overall survival (OS) or LRC between the two regimens. The OS at two years was 68% for AF and 67% for CF. The corresponding figures for LRC were 71% and 67%, respectively. There was a trend towards improved LRC for oral cancers treated (p=0.07) and for large tumours (T3-T4) (p=0.07) treated with AF. The AF group had significantly worse acute reactions, while there was no significant increase in late effects. Conclusion: Overall the AF regimen did not prove to be more efficacious than CF. However, the trend towards improved results in AF for oral cancers needs to be further investigated.
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