Sökning: "subarctic tundra"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden subarctic tundra.

  1. 1. The hidden life of plants : fine root dynamics in northern ecosystems

    Författare :Gesche Blume-Werry; Roland Jansson; Ann Milbau; Scott D. Wilson; Isla Myers-Smith; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Arctic; belowground; boreal; climate change; fine roots; heath; meadow; minirhizotron; permafrost; phenology; plant community; root biomass; root growth; root litter; root production; subarctic; tundra;

    Sammanfattning : Fine roots constitute a large part of the primary production in northern (arctic and boreal) ecosystems, and are key players in ecosystem fluxes of water, nutrients and carbon. Data on root dynamics are generally rare, especially so in northern ecosystems. LÄS MER

  3. 2. Soil Organic Matter Dynamics and Methane Fluxes at the Forest – Tundra Ecotone in Fennoscandia

    Författare :Sofie Sjögersten; Gaius Shaver; Uppsala universitet; []
    Nyckelord :Decomposition; forest – tundra ecotone; environmental change; Fennoscandia; methane; soil organic matter; subarctic.; naturgeografi; Physical Geography;

    Sammanfattning : This thesis presents results from several studies that have focused on the carbon and nutrient dynamics in soils at the forest – tundra ecotone in Fennoscandia. The main objectives of the study were: (i) to investigate the links between the physical environment, above-ground vegetation communities, soil carbon storage, nutrient status and the chemical composition of the soil organic matter (SOM), and (ii) to quantify trace gas fluxes (methane and carbon dioxide) between mesic soils and the atmosphere. LÄS MER

  4. 3. Phosphorus availability and microbial respiration across biomes : from plantation forest to tundra

    Författare :Camilla Esberg; Reiner Giesler; David A. Wardle; Bente J. Graae; Dan Binkley; Umeå universitet; []
    Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; phosphorus availability; microbial bioassay; soil respiration; microbial growth rate; Hedley fractionation; soil sorption; weathered soils; boreal forest; subarctic and tundra;

    Sammanfattning : Phosphorus is the main limiting nutrient for plant growth in large areas of the world and the availability of phosphorus to plants and microbes can be strongly affected by soil properties. Even though the phosphorus cycle has been studied extensively, much remains unknown about the key processes governing phosphorus availability in different environments. LÄS MER

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

    Författare :Maria Olsrud; Institutionen för naturgeografi och ekosystemvetenskap; []
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

  7. 5. Temporal and spatial variability of carbon cycling in a subarctic landscape

    Författare :Torbjörn Johansson; Institutionen för naturgeografi och ekosystemvetenskap; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geologi; physical geography; Geology; Växtekologi; Plant ecology; Permafrost; Herbivory; Subarctic; Aerial photography; Vegetation change; Carbon balance; fysisk geografi;

    Sammanfattning : This thesis deals with the carbon balance in a subarctic landscape at different temporal and spatial scales. Its focus is mainly on the peatland and mountain birch forest (Betula pubescens ssp. czerepanovii) ecosystems within the Abisko area in northernmost Sweden. This is an area with a temperature close to the 0 OC mean annual isotherm. LÄS MER