| 1. |
- Dinnétz, Patrik, et al.
(författare)
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Population viability analysis of Saxifraga cotyledon, a perennial plant with semelparous rosettes
- 2002
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Ingår i: Plant Ecology. - 1385-0237 .- 1573-5052. ; 159:1, s. 61-71
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Tidskriftsartikel (refereegranskat)abstract
- The aim with this study was to analyse the population dynamics of Saxifraga cotyledon, a rare, long lived herb, with semelparous rosettes. In Sweden, S. cotyledon grows in fragmented habitats at high altitude and is classified as vulnerable according to the IUCN system. From a five year demographical study we estimated population growth rates and extinction risks for one small and one large subpopulation. In the small subpopulation deterministic matrix simulations showed large variation, with two transitions projecting negative and two projecting positive population growth. The large subpopulation also showed large variation, but all yearly transitions projected positive population growth. In both subpopulations survival and growth contributed more than twice as much to population growth rates than did sexual reproduction, vegetative reproduction and the seed bank all taken together. In stochastic simulations the maximum likelihood growth estimator was larger than 1 for both subpopulations. None of the two subpopulations suffer from high extinction rates and although the effect of demographic stochasticity increase extinction risk in small populations it is enough with 70 individuals for a viable population of S. cotyledon. Hence, for the studied population of S. cotyledon, rareness per se is not a good indicator of vulnerability.
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| 2. |
- Gustafsson Gillbrand, Patrik
(författare)
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Stenbruk : Stenartefakter, råmaterial och mobilitet i östra Mellansverige under tidig- och mellanmesolitikum
- 2018
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis examines artefacts, raw materials and lithic technology between c. 9200–6200 cal BC in Eastern Central Sweden. The overall purpose of this study is to investigate when people first came to Eastern Central Sweden and where they came from. More precisely, it provides a typological, geographical and chronological survey of artefacts and the use of different raw materials. The study deals with assemblages with artefacts from more than thirty archaeologically excavated sites and loose finds in Eastern Central Sweden. The objects consist of chubby pecked axes, core axes, flake axes, shaft hole picks, microliths and micro burins, points, burins, rulers, unifacial blade core, conical cores, micro blade cores, blades, drills, retouched blades and micro blades. The artefacts have been compared with established typologies and chronologies for the rest of the Nordic countries and to some extent Russia and the Baltic States. An analysis of different raw materials present at Early and Middle Mesolithic sites in Eastern Central Sweden was also carried out. The materials are put into a chronological and geographical context. The raw materials included in the study are the non-local rocks flint and Cambrian flint, as well as local raw materials such as quartz, greenstone, local vulcanite, mylonite and red porphyry. From 9200 cal BC there is evidence of the first groups of people in the area, just shortly after that the Weichselian ice cap had withdrawn. Throughout the period studied the artefacts as well as the non-local raw materials exhibit great similarities to those found in the western part of Sweden. The study also shows, regarding the use of different raw materials and presence of certain artefacts, that some major events took place, suggesting a new chronological time frame for the Early- and Middle Mesolithic periods. In addition, a discussion regarding mobility and migration in Eastern Central Sweden during Early Post Glacial time is carried out.
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