Search for dissertations about: "permafrost history"

Showing result 1 - 5 of 6 swedish dissertations containing the words permafrost history.

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

   Author : A. Britta K. Sannel; Peter Kuhry; Peter Jansson; Ian Brown; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; peatlands; permafrost; carbon accumulation; fire; subarctic; Holocene; Physical geography; Naturgeografi;

   Abstract : 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. READ MORE

4. 2. Subarctic ecosystem responses to climate, catchment and permafrost dynamics in the Holocene

   Author : Ulla Kokfelt; Kvartärgeologi; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; subarctic Sweden; palsa mire development; peat; permafrost history; carbon and nutrient cycling; lake sediments;

   Abstract : This thesis assesses aspects of the wetland development, permafrost dynamics and associated changes in carbon and nutrient cycling of the Stordalen Mire in northern Sweden. Various ecological and biogeochemical analyses of one peat and two lake sediment sequences were conducted, including analyses of organic matter and carbonate content, mosses, diatoms, testate amoebae, pigments, carbon and nitrogen and their stable isotopes, near infrared spectroscopy and biogenic silica. READ MORE

5. 3. Temporal and spatial dynamics in subarctic peat plateaus and thermokarst lakes

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

   Abstract : 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. READ MORE

6. 4. The Torneträsk System - A basis for predicting future subarctic ecosystems

   Author : Didac Pascual; BECC: Biodiversity and Ecosystem services in a Changing Climate; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; climate change; carbon fluxes; ecosystem change; climate projections; rain on snow; modelling; impacts; snow; permafrost; winter warming events;

   Abstract : Arctic and subarctic areas have experienced a rapid warming and substantial increases in precipitation in recent decades. The frequency and intensity of some extreme events, such as fires, winter warming events, extreme rainfall, and droughts, has also increased. READ MORE

7. 5. Palaeogenomic reconstruction of woolly mammoth evolutionary history and extinction dynamics

   Author : Marianne Dehasque; Love Dalén; David Díez-del-Molino; Rike Stelkens; Rebecca N. Johnson; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; woolly mammoth; Mammuthus primigenius; extinction; Wrangel Island; ancient DNA; palaeogenomics; radiocarbon dating; structural variants; genome erosion; population structure; Systematic Zoology; zoologisk systematik och evolutionsforskning;

   Abstract : Biodiversity is declining globally. Yet, the biological and genetic processes associated with these declines on a longer timescale are still poorly understood. Ancient DNA is a powerful tool to study evolution in real-time. Despite advances in the field, there is further need for refinement of laboratory and computational techniques. READ MORE