Search for dissertations about: "July"

Showing result 1 - 5 of 119 swedish dissertations containing the word July.

2. 1. Diatoms as indicators of Holocene climate and environmental change in northern Sweden

   Author : Christian Bigler; Ingemar Renberg; Roland Hall; N. John Anderson; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Physical geography and sedimentology; diatoms; Holocene; paleolimnology; climate change; lake sediments; transfer functions; quantitative environmental reconstructions; northern Sweden; Abisko; Naturgeografi och sedimentologi; Physical geography; Naturgeografi; naturgeografi; Physical Geography;

   Abstract : The objective of the thesis was to explore the potential of diatoms (Bacillariophyceae) as indicators of Holocene climate and environmental change in northern Sweden (Abisko region, 68°21'N, 18°49'E). A modern surface-sediment calibration set including 100 lakes was developed and lake-water pH, sedimentary organic content (assessed by loss-on-ignition) and temperature were identified as most powerful environmental variables explaining the variance within the diatom assemblages. READ MORE

4. 2. Flagellates in the marine microbial food web : the ecology of a mixotrophic nanoflagellate, Ochromonas sp

   Author : Agneta Andersson-Nordström; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Microbial food web; flagellates; Ochromonas sp.; mixotrophy; size- selective grazing; remineralisation; excretion of DFAA;

   Abstract : Nanoflagellates were found to be abundant in a coastal area of the northern Bothnian Sea. The maximum concentration of nanoflagellates, approximately 8000 cells ml-1, was observed in July, coinciding with a decrease in the abundance of cyanobacteria. READ MORE

5. 3. Insect Diversity in Changing Landscapes

   Author : Markus Franzén; Biologiska institutionen; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; växtparasitologi; Entomologi; plant parasitology; Zoology; Zoologi; Entomology; Ekologi; Ecology; butterfly; bee; dispersal; extinction; Djurekologi; Animal ecology;

   Abstract : During recent decades, concern about the loss of biodiversity has increased. To change this negative trend there is an urgent need for effective conservation measures and there are ample evidence that conservation of organisms without an understanding of their ecology and behaviour is impossible. READ MORE

6. 4. The sensitivity of Swedish alpine lakes to hydro-climatic changes during the Late Holocene

   Author : Annika Berntsson; Gunhild Rosqvist; Peter G. Langdon; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; alpine lake sediments; temperature reconstruction; precipitation; catchment erosion; chironomids; oxygen isotopes; XRF core scanning; geomorphology; grain size analysis; kvartärgeologi; Quaternary Geology;

   Abstract : The thesis objective is to use lake sediments to investigate the relationships between chironomids, as proxy for temperature, and δ18O and minerogenic in-wash, as precipitation proxies, in northern Sweden during the Late Holocene. Three lakes along a N–S transect in the Scandes were studied using biological, geochemical and physical sediment properties, together with numerical methods. READ MORE

7. 5. Seasonal flight patterns of the Spruce bark beetle (Ips typographus) in Sweden : phenology, voltinism and development

   Author : Petter Öhrn; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
   Keywords : LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES;

   Abstract : The major bark beetle threat to Norway spruce (Picea abies (L.) Karst.) in Eurasia is the spruce bark beetle Ips typographus. Beetles cause damage after population build-up in defenseless trees. READ MORE