Sökning: "subarctic"

Visar resultat 11 - 15 av 75 avhandlingar innehållade ordet subarctic.

  1. 11. Carbon gas biogeochemistry of a northern peatland - in a dynamic permafrost landscape

    Författare :Kristina Bäckstrand; Patrick M. Crill; Torben R. Christensen; David Bastviken; Kimberly P. Wickland; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Carbon balance; Carbon exchange; Peatland; Subarctic; Climate change; Earth sciences; Geovetenskap; geokemi; Geochemistry;

    Sammanfattning : This thesis is about biogeochemical processes of a northern peatland and their importance as a link between the climate and the terrestrial system. Increased temperatures on a global level, and particularly in the Arctic, have led to melting permafrost and changes in hydrology. LÄS MER

  3. 12. 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

  4. 13. Holocene climate and environmental change in high latitudes as recorded by stable isotopes in peat deposits

    Författare :Päivi Kaislahti Tillman; Steffen Holzkämper; Stefan Wastegård; Peter Kuhry; Thomas W. D. Edwards; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; stable isotopes; Holocene; subarctic; climate; Sphagnum fuscum; kvartärgeologi; Quarternary Geology;

    Sammanfattning : In this thesis, stable carbon and oxygen isotopes in α-cellulose isolated from Sphagnum fuscum moss remains were used as climate proxies. The main focus was to implement the methods in records from high latitude peatlands in the Northern Hemisphere (west-central Canada and north-eastern European Russia), reconstruct palaeoclimate of the studied regions during the Holocene, and evaluate the compatibility of results with other proxy records, especially tree-ring isotope time-series. LÄS MER

  5. 14. Temperature effects on UV-B induced DNA damage and repair in plants and a lichen

    Författare :Markus Paulsson; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Tobacco Nicotiana tabacum ; Temperature; Subarctic; Plants; Photoreactivation; Photolyase; Lichen; DNA damage; Cyclobutane pyrimidine dimers CPD ; 6-4 Photoproducts; Cladonia arbuscula ssp. mitis; Ultraviolet radiation; UV-B; Vaccinium vitis-idaea; Plant genetics; Växtgenetik;

    Sammanfattning : All living organisms have DNA and since DNA is essential to life it must be repaired when damaged. UV radiation is one of the major DNA damaging agents, which photosynthetic organisms cannot avoid. LÄS MER

  7. 15. 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