Sökning: "lake ecosystem"

Visar resultat 21 - 25 av 81 avhandlingar innehållade orden lake ecosystem.

  1. 21. Towards aquatic assessment of Lake Tumba, DR Congo

    Författare :Lingopa Norbert Zanga; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
    Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES;

    Sammanfattning : The livelihoods of most communities around the 765 km2 Lake Tumba are dependent on fish from the lake. Artisanal fishing and other pressures on the aquatic ecosystem are likely to have increased over the last half century. However, few monitoring programs follow these pressures and their influence on the aquatic ecosystem. LÄS MER

  3. 22. The decline of great Arctic charr in Lake Vättern : empirical and theoretical analyses of suggested causes

    Författare :Malin Setzer; Tomas Jonsson; Bo Ebenman; Mark C. Emmerson; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Naturvetenskap;

    Sammanfattning : Human activity is affecting species and ecosystems all over the world. In aquatic systems negative trends can be seen for many fish stocks and potential consequences of this, for ecosystem structure and functions, are of particular concern. LÄS MER

  4. 23. The natural holocene vegetation development and the introduction of agriculture in northern Norrland, Sweden : studies of soil, peat and especially varved lake sediments

    Författare :Ulf Segerström; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Jordbruk-- Sverige -- Norrbotten; Växtekologi-- Sverige -- Norrbotten; Lule älvdal;

    Sammanfattning : The Holocene vegetation history of northern Norrland was studied by pollen analysis of sediement, peat and soil samples, with the aim to improve our knowledge about vegetation development in northern Norrland, and also about the history of man and the introduction of agriculture in the area. Earlier made pollen analyses from the four northernmost provinces were summarized and a series of new analyses from northern Norrland added. LÄS MER

  5. 24. Terrestrial response to Dansgaard-Oeschger cycles and Heinrich events : the lacustrine record of Les Echets, south-eastern France

    Författare :Daniel S. Veres; Barbara Wohlfarth; John J. Lowe; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; lake sediments; palaeoclimate; organic matter; Dansgaard-Oeschger cycles; Heinrich events; MIS 3; Western Europe; Quaternary geology; Kvartärgeologi; Quarternary Geology; kvartärgeologi;

    Sammanfattning : Marine Isotope Stage (MIS) 3 was an interval characterized by large and abrupt temperature changes on a millennial time scale, the so-called Dansgaard-Oeschger (DO) cycles and Heinrich events. Evidence for this high-frequency climate variability has been identified in many marine and ice core records. LÄS MER

  7. 25. Temporal and spatial dynamics in subarctic peat plateaus and thermokarst lakes

    Författare :A. Britta K. Sannel; Peter Kuhry; Peter Jansson; Ian A. Brown; Serge Payette; Stockholms universitet; []
    Nyckelord :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