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Visar resultat 21 - 24 av 24 avhandlingar som matchar ovanstående sökkriterier.

  1. 21. 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

  3. 22. Carbon exchange in boreal ecosystems: upscaling and the impacts of natural disturbances

    Författare :Julia Kelly; BECC: Biodiversity and Ecosystem services in a Changing Climate; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Carbon fluxes; CH4; Climate change; CO2; Drought; Ecosystem respiration; Forest; Peatland; Remote sensing; Temperature; Thermal camera; UAV; Wildfire;

    Sammanfattning : Boreal forests and peatlands are globally significant carbon stores but they are threatened by rising air temperatures and changes in precipitation regimes and the frequency of natural disturbances. Predicting how the boreal biome will respond to climate change depends on being able to accurately model and upscale the greenhouse gas fluxes between these ecosystems and the atmosphere. LÄS MER

  4. 23. Large-Scale Multi-Source Satellite Data for Wildfire Detection and Assessment Using Deep Learning

    Författare :Xikun Hu; Yifang Ban; Martin Wooster; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Wildfire; Remote Sensing; Active Fire Detection; Burned Area Mapping; Burn Severity Assessment; Sentinel-2; Landsat; Sentinel-1; Deep Learning; Semantic Segmentation; Image Translation; Skogsbrand; fjärranalys; aktiv branddetektering; kartläggning av bränt område; bedömning av brännskador; Sentinel-2; Landsat; Sentinel-1; djupinlärning; semantisk segmentering; bildöversättning.; Geoinformatik; Geoinformatics;

    Sammanfattning : Earth Observation (EO) satellites have great potential in wildfire detection and assessment at fine spatial, temporal, and spectral resolutions. For a long time, satellite data have been employed to systematically monitor wildfire dynamics and assess wildfire impacts, including (i) to detect the location of actively burning spots, (ii) to map the spatial extent of the burn scars, (iii) to assess the wildfire damage levels. LÄS MER

  5. 24. Impacts and drivers of insect herbivory on element cycling in forests globally

    Författare :Bernice Hwang; MERGE: ModElling the Regional and Global Earth system; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; biogeochemical cycling; folivory; insect cadavers; insect frass; insect herbivory; litter decomposition; nutrient cycling; carbon; nitrogen; phosphorus; silicon; silica;

    Sammanfattning : The effects of insect herbivores on forest functioning are not well understood even though they can have important impacts on ecosystem processes by intercepting foliage before resorption and depositing nutrient-rich materials to the soil. In this thesis, I investigated the impact and drivers of insect folivores on carbon (C), nitrogen (N), phosphorus (P) and silica (Si) cycling in broadleaf forests, and how this varies with major climate variables. LÄS MER