Search for dissertations about: "tree-line"

Showing result 1 - 5 of 8 swedish dissertations containing the word tree-line.

  2. 1. Mosses as mediators of climate change : implications for tree seedling establishment in the tundra

    Author : Signe Lett; Ellen Dorrepaal; David Wardle; Marie-Charlotte Nilsson; Vigdis Vandvik; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; arctic; alpine; B. pubescens; bryophytes; competition; facilitation; mosses; P. sylvestris; precipitation changes; seedlings; traits; tree line; warming;

    Abstract : Alpine and arctic tree line expansion depends on the establishment of tree seedlings above the current tree line, which is expected to occur with climate warming. However, tree lines often fail to respond to higher temperatures. Other environmental factors are therefore likely important for tree seedling establishment. READ MORE

  4. 2. Holocene vegetation dynamics and climate changes in the Torneträsk area, northern Sweden

    Author : Lena Barnekow; Kvartärgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Paleobotanik; palynology; phylogeny; Palaeobotany; northern Sweden; Torneträsk; Abisko; lake-level; radiocarbon dating; forest history; Holocene; tree-line; climate; Vegetation; fylogeni; palynologi; Physical geography; geomorphology; pedology; cartography; climatology; Fysisk geografi; geomorfologi; marklära; kartografi; klimatologi;

    Abstract : The aim of this study was to reconstruct the Holocene vegetation history and the climate changes in a subarctic area. The results are based on pollen and macrofossil records from six lakes in the Torneträsk area. The lakes are situated at altitudes between 370 and 999 m a.s. READ MORE

  5. 3. Reproductive patterns of birches (Betula spp.) in northern Sweden

    Author : Stig-Olov Holm; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Reproduction; Betula; seed-quality; seed-set; pollination; pollen-limitation; pollen-competition; tree-line; environmental gradient; seed weight; seedling survival; Semudobia;

    Abstract : The aim of this thesis was to study patterns of reproduction of Betula pendula and B. pubescens coll. along an altitudinal, coastal-inland, gradient in northern Sweden. The altitudinal variation was related to the distribution of the birch taxa along the gradient. READ MORE

  6. 4. The role of vegetation dynamics in the control of atmospheric CO2 content

    Author : Stephen Sitch; Biologiska institutionen; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Atmospheric CO2 content; climate change; plant functional types; terrestrial biosphere model; DGVM; vegetation dynamics; land use; land cover change; Plant ecology; Växtekologi;

    Abstract : This thesis contains a description of the Lund-Potsdam-Jena Dynamic Global Vegetation Model (LPJ-DGVM) and its application to infer the role of vegetation dynamics on atmospheric CO2 content at different time-scales. The model combines vegetation dynamics and biogeochemistry in a modular framework. READ MORE

  7. 5. Distribution and abundance of genetic variation in the arctic fox

    Author : Love Dalén; Anders Angerbjörn; Robert K. Wayne; Stockholms universitet; []
    Keywords : population genetics; DNA; ecology; population history; gene flow; Alopex lagopus;

    Abstract : This thesis investigates how changes in population size and spatial movements of individuals have shaped the distribution and abundance of neutral genetic variation in the arctic fox. This is done through mitochondrial and microsatellite DNA analyses on samples covering most of the species’ distribution, but with special emphasis on Scandinavia. READ MORE