Sökning: "introduced species"

Visar resultat 1 - 5 av 185 avhandlingar innehållade orden introduced species.

1. 1. Biologisk mångfald i läroböcker i biologi

   Författare :Maria Ferlin; Högskolan i Borås; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; textbooks; biological diversity; social semiotics; multimodality; meaning making; concept; species; species concept; Utbildningsvetenskap med inriktning mot naturvetenskap; Textbooks; Biological diversity; Social semiotics; Multimodality; Meaning making; Concept; Species; Species concept;

   Sammanfattning : The aim of this thesis is to analyse offered meaning, that is, what and how subject content is communicated to the recipients. In this case the subject content is biological diversity and the communicative artefacts are biology books for the latter grades in the Swedish compulsory school. LÄS MER

3. 2. Instrumental and methodological developments for isotope dilution analysis of gaseous mercury species

   Författare :Tom Larsson; Erik Björn; Holger Hintelmann; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Mercury; gas; species; speciation analysis; isotope dilution analysis; permeation tubes; Analytical chemistry; Analytisk kemi;

   Sammanfattning : This thesis deals with instrumental and methodological developments for speciation analysis of gaseous mercury (Hg(g)), based on isotope dilution analysis (IDA). The studied species include Hg0, (CH3)2Hg, CH3HgX and HgX2 (where X symbolises a negatively charged counter ion in the form of a halide or hydroxyl ion). LÄS MER

4. 3. Biotic resistance in freshwater fish communities

   Författare :Anna Henriksson; Göran Englund; David Wardle A.; Jun Yu; Sebastian Diehl; Donald Jackson; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; biotic resistance; freshwater fish; introductions; invasions; invasion success; invasibility; invasiveness; species richness; saturation; species identity; weighted species richness;

   Sammanfattning : Invasions of non-native species cause problems in ecosystems worldwide, and despite the extensive effort that has been put into research about invasions, we still lack a good understanding for why some, but not other, communities resist these invasions. In this doctoral thesis I test hypotheses on biotic resistance using a large dataset of more than 1000 both failed and successful introductions of freshwater fish into Swedish lakes. LÄS MER

5. 4. Effects of climate change on boreal wetland and riparian vegetation

   Författare :Lotta Ström; Roland Jansson; Christer Nilsson; Sarah Gergel; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; biomass; flooding; hydrologic niche; invasibility; riparian zone; riparian plant species; river margin; climate scenario; seed sowing experiment; species composition; species richness; transplant experiment; Terrestrial ecology; Terrestrisk ekologi;

   Sammanfattning : Models of climate change predict that temperature will increase during the 21th century and the largest warming will take place at high northern latitudes. In addition to warming, predictions for northern Europe include increased annual precipitation and a higher proportion of the precipitation during winter falling as rain instead of snow. LÄS MER

7. 5. The threat from non indigenous species - ecosystem vulnerability, global distribution and co-occurrence with other major threats

   Författare :Helena Berglund; Biodiversitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; threats; distribution range; isolation; endemism; invasions; invaders; vulnerability; non indigenous species; rarity; threatened species;

   Sammanfattning : We live in a globalised world where people and goods travel large distances. Various species are brought along on these journeys, intentionally or as hitchhikers. Some of these species establish populations in regions to which they could not have spread without human assistance, and where they are considered to be non indigenous species (NIS). LÄS MER