Search for dissertations about: "shrub birch"

Found 5 swedish dissertations containing the words shrub birch.

2. 1. Circumpolar impacts of herbivores on Arctic tundra vegetation

   Author : Elin Lindén; Johan Olofsson; Maja K. Sundqvist; Mariska te Beest; Elisabeth S. Bakker; Umeå universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; herbivores; grazing; Arctic; circumpolar; tundra; vegetation; plant defence; secondary metabolites; shrub birch; exclosures; vegetation; species diversity; biology; biologi;

   Abstract : Arctic tundra vegetation provides many ecological services that have implications for the global climate. However, the tundra biome is currently changing in response to increasing temperatures. Herbivores may mitigate some of these responses to warming through their impact on Arctic vegetation. READ MORE

4. 2. Temporal variation and phytotoxicity of Batatasin-III produced by Empetrum hermaphroditum

   Author : Anna Wallstedt; Biologiska institutionen; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Palaeobotany; nitrogen uptake; photosynthesis; inhibition; temporal variation; chemical interference; boreal forest; Empetrum hermaphroditum; batatasin-III; phylogeny; palynology; Paleobotanik; fylogeni; palynologi; Biology; Biologi;

   Abstract : In northern Sweden, the clonal dwarf shrub Empetrum hermaphroditum Hagerup exerts strong inhibitory effects on other plant species. These inhibitory effects may, at least in part, be attributed to the high production of the secondary metabolite, batatasin-III, which is released from leaves and transported to the soil by rain (throughfall) and snowmelt. READ MORE

5. 3. Mechanisms of below-ground carbon cycling in subarctic ecosystems

   Author : Maria Olsrud; Institutionen för naturgeografi och ekosystemvetenskap; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; cartography; climatology; Fysisk geografi; geomorfologi; marklära; kartografi; klimatologi; pedology; geomorphology; Physical geography; subarctic tundra; phosphorous mobilization; organic acids; open top chamber experiment; 15N natural abundance; Ericoid mycorrhizas; global change; 14C pulse-labelling; Carbon allocation;

   Abstract : Some components of the below-ground carbon (C) cycle in terrestrial ecosystems are still poorly understood. A better understanding will be necessary to predict adequately the impacts of global change factors on C cycling and storage, especially in high-latitude ecosystems, where much of the C is stored below-ground. READ MORE

6. 4. Effects of herbivory on arctic and alpine vegetation

   Author : Åsa Lindgren; Ove Eriksson; Jon Moen; Anders Angerbjörn; Ingibjörg S Jónsdóttir; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; herbivory; reindeer; rodents; functional traits; plant species composition; arctic; alpine; tundra; seed limitation; Carex bigelowii; Biology; Biologi; Plant Ecology; växtekologi;

   Abstract : The distribution of plant species and functional traits in alpine and arctic environments are determined by abiotic conditions, but also by biotic interactions. In this thesis, I investigate interactions among plants and herbivory effects on plant community composition and plant functional traits in three different regions: Swedish Lapland, Beringia (USA/Russia) and Finnmark (Norway). READ MORE

7. 5. Effects of enhanced ultraviolet-B radiation on subarctic ecosystems

   Author : Carola Gehrke; Biologiska institutionen; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; pigmentation; photosynthesis; dark respiration; shoot morphology; shoot growth; phanerogams ; species composition cryptogams; productivity; decomposition; dwarf shrubs; bryophytes; peatland ecosystem; heath ecosystem; UV-B; ozone depletion; Plant ecology; Växtekologi;

   Abstract : Biologically harmful ultraviolet-B radiation (UV-B, 280-320 nm) is increasing at the Earth´s surface owing to stratospheric ozone depletion. This is of global concern due to potential impacts of enhanced UV-B radiation on the biosphere. READ MORE