Sökning: "nitrogen accumulation"

Visar resultat 1 - 5 av 61 avhandlingar innehållade orden nitrogen accumulation.

  1. 1. The nitrogen economy of mountain birch : As related to environmental conditions and genotype

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Martin Weih; Uppsala universitet.; [1998]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ecology; Betula pubescens ssp. czerepanovii; growth; nitrogen; subarctic; temperature; ultraviolet radiation; Ekologi; NATURAL SCIENCES Biology Terrestrial; freshwater and marine ecology; NATURVETENSKAP Biologi Terrestisk; limnisk och marin ekologi; ekologisk botanik; Ecological Botany;

    Sammanfattning : Responses of mountain birch growth to changed environmental conditions arestrongly affected by birch genotype, and nitrogen economy is a key factor influencingthe winter survival of first-year seedlings. These are some of the findings of a series ofstudies, in which growth, nitrogen economy and winter survival were analysed usingpot-grown seedlings of mountain birch (Betula pubescens ssp. LÄS MER

  2. 2. Responses of peatland vegetation to enhanced nitrogen

    Detta är en avhandling från Umeå : Ekologi, miljö och geovetenskap

    Författare :Magdalena Wiedermann; Umeå universitet.; [2008]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sphagnum; nitrogen; peatlands; soluble amino acids; gradient study; field experiment; NATURAL SCIENCES Biology; NATURVETENSKAP Biologi;

    Sammanfattning : Human alteration of the global nitrogen (N) cycle has had major impacts on naturally N-limited ecosystems worldwide. Peatlands, dominated by peat mosses, Sphagnum species, represent one such sensitive ecosystem. LÄS MER

  3. 3. The Positive Effect of Nitrogen Alloying of Tool Steels Used in Sheet Metal Forming

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Irma Heikkilä; Uppsala universitet.; [2013]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; galling; nitrogen; tool steel; sliding contact; metal forming; Teknisk fysik med inriktning mot tribomaterial; Engineering Science with specialization in Tribo Materials;

    Sammanfattning : Sheet metal forming processes are mechanical processes, designed to make products from metal sheet without material removal. These processes are applied extensively by the manufacturing industry to produce commodities such as heat exchangers or panels for automotive applications. They are suitable for production in large volumes. LÄS MER

  4. 4. Temporal and spatial dynamics in subarctic peat plateaus and thermokarst lakes

    Detta är en avhandling från Stockholm : Department of Physical Geography and Quaternary Geology (INK), Stockholm University

    Författare :A. Britta K. Sannel; Stockholms universitet.; [2010]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Peatlands; permafrost; subarctic; peat plateau; thermokarst lake; macrofossil analysis; carbon nitrogen ratio; peat accumulation; carbon accumulation; remote sensing; binary encoding; time-series analysis; Physical Geography; naturgeografi;

    Sammanfattning : Permafrost peatlands are widespread at high northern latitudes and are important soil organic carbon reservoirs. A future warming in these areas, as suggested by global climate models, can cause thawing and increased ground subsidence (thermokarst), resulting in changes in surface hydrology and ecosystem functioning. LÄS MER

  5. 5. Holocene dynamics in subarctic peat plateaus of west-central Canada : Vegetation succession, peat accumulation and permafrost history

    Detta är en avhandling från Stockholm : Institutionen för naturgeografi och kvartärgeologi

    Författare :A. Britta K. Sannel; Stockholms universitet.; [2007]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; peatlands; permafrost; carbon accumulation; fire; subarctic; Holocene; NATURAL SCIENCES Earth sciences Exogenous earth sciences Physical geography; NATURVETENSKAP Geovetenskap Exogen geovetenskap Naturgeografi;

    Sammanfattning : Dynamics in vegetation, permafrost and peat and net carbon accumulation rates throughout the Holocene have been studied in two subarctic peat plateaus of west-central Canada through plant macrofossil analysis, geochemical analyses and AMS radiocarbon dating. Peatland formation at the studied sites began around 6600-5900 cal yr BP as a result of paludification of upland forests. LÄS MER