Syftet med det här projektet är att göra en paleoekologisk studie för att utvärdera om makrofossilanalys kan användas som självständigt redskap för att göra en miljöbeskrivning av sedimentborrkärnan från Lina myr, samt att se om det finns tillräckligt material i borrkärnan för att göra kol-14 dateringar. Makrofossil är alla spår av djurliv och växtliv i jordlagren som man kan observera okulärt, exempelvis fröer, benrester och träkol. Genom att studera makrofossil så är det möjligt få en bild av resursutnyttjandet i ett område eller se spår av biologiskt liv. Projektet baseras på material som kommer från Lina myr som ligger på den östra delen av Gotland. Området är ca 900 hektar stort och ligger på en kalkstensgrund. Under hösten 2016 påbörjades ett projekt med syfte att undersöka landskapets och människans interaktion i området med fokus på Lina myr där landskapsförändringar som skett under 8 000 år ska studeras med hjälp av olika metoder. Studierna kombinerar paleoekologiska, arkeologiska och samhällsgeografiska perspektiv.  Genom våtsiktning och med hjälp av mikroskop studerades material från borrkärnan tagen vid Lina myr. Ett fåtal fröer hittades tillsammans med en del insektsdelar och molluskskal. Förhoppningen var att hitta material för en kol-14 datering, men endast mycket små delar träkol hittades och de flesta av fröerna var inte lämpliga för datering. Tolkningen av de artbestämda fröernas ekologi resulterade i slutsatsen att det funnits vatten i området länge som varit sött och/eller bräckt. Detta antagande stärktes av fynd av Chara som återfanns i prover från nästan alla lager. Dock fanns det för lite material för att göra en miljöbeskrivning av området. En rekommendation var att även utföra en diatoméanalys och eventuellt även en pollenanalys, för att få en tydligare bild av landskapsutvecklingen.

<p>Mires surface energy and water budgets govern the conditions for climatic, hydrological, ecological and carbon balance processes. The components of the water and surface energy budgets were quantified over two growing seasons for an open boreal mire. The measurements of fluxes were complemented with data on the spatial variation of water content and temperature in different micro-relief elements (hummocks and hollows). Since measurements on mires are scarce, special investigations of aerodynamic properties were done as well as a calibration of TDR function for peat. The partitioning of available energy at the surface depended mainly on air temperature and relative humidity. There was a trend of falling Bowen ratio both during the day and during the season from May (monthly value 0.9) to September (0.6). The bulk surface resistance (<i>r</i>_s) to evapotranspiration was considerable and varied little (mean <i>r</i>_s = 160 s m^-1). The cause of its relatively large value could be found in a great aerodynamic resistance within the canopy layer, and the peat wetness variation influenced little. In the scale of the whole mire, the water storage were similar over the central, open areas. On a smaller scale, the presence of a pronounced micro-topography caused a variation of the surface wetness. This was also reflected in the spatial variation of soil temperatures. The heat storage in hummock was largely influenced by lateral heat fluxes. There were considerable effects of peat elasticity and approximately 40 % of the changes in water storage was caused by swelling/shrinking of the whole peat mound. This effect should be incorporated in future models of mire-water dynamics.</p>

Mires surface energy and water budgets govern the conditions for climatic, hydrological, ecological and carbon balance processes. The components of the water and surface energy budgets were quantified over two growing seasons for an open boreal mire. The measurements of fluxes were complemented with data on the spatial variation of water content and temperature in different micro-relief elements (hummocks and hollows). Since measurements on mires are scarce, special investigations of aerodynamic properties were done as well as a calibration of TDR function for peat. The partitioning of available energy at the surface depended mainly on air temperature and relative humidity. There was a trend of falling Bowen ratio both during the day and during the season from May (monthly value 0.9) to September (0.6). The bulk surface resistance (rs) to evapotranspiration was considerable and varied little (mean rs = 160 s m-1). The cause of its relatively large value could be found in a great aerodynamic resistance within the canopy layer, and the peat wetness variation influenced little. In the scale of the whole mire, the water storage were similar over the central, open areas. On a smaller scale, the presence of a pronounced micro-topography caused a variation of the surface wetness. This was also reflected in the spatial variation of soil temperatures. The heat storage in hummock was largely influenced by lateral heat fluxes. There were considerable effects of peat elasticity and approximately 40 % of the changes in water storage was caused by swelling/shrinking of the whole peat mound. This effect should be incorporated in future models of mire-water dynamics.

Peatlands are important ecosystems that provide ecohydrological functions related to carbon storage and cycling, water quality, flood attenuation, and groundwater recharge. One key characteristic that gives peatlands these functions is the capacity to swell and shrink upon wetting and drying, commonly referred to as peat volume change. This property of peat volume change is closely related to the fluctuations of the water table and has a buffering effect on the water table depth relative to the peat surface, which acts as an important control on many ecohydrological functions such as carbon cycling, vegetation composition, and biogeochemical processes. In an attempt to fill a gap of knowledge, this thesis investigated peat volume change for multiple Northern peatlands close to Umeå, Sweden, using groundwater level and mire surface level data obtained during the summer of 2021. The objectives were to investigate the temporal trends and characteristics of changes in the water table and peat volume at the studied site and to determine how peat volume change capacity differs for mires of different ages, as well as different land management such as natural, drained and restored peatlands. It was found that old (older than 2000 years) mires have a significantly smaller peat volume change capacity compared to young mires (younger than 1000 years), as well as smaller specific storage, indicating that factors that change as the peatland evolves are important for the ability to expand and contract. It was also found that the relationship between the mire surface and water level was linear for some mires but not for others, including drained and old mires. For the drained mires this could be explained by very deep water tables compared to the natural mires, however, they did not stand out among the natural mires concerning peat volume change capacity. The comparison between a restored mire and a drained gave ambiguous results. It was also found that the specific storage, which is directly related tothe compressibility of the peat, was greater during drying conditions compared to rewetting conditions, highlighting peatlands ability to maintain wet conditions. The study provides a deeper understanding of peat volume change in Northern peatlands and the factors related to this phenomenon, which is crucial for further studying of peatland ecohydrology. / Torvmarker är viktiga ekosystem som bidrar med ekohydrologiska funktioner relaterade till kollagring och kolcykling, vattenkvalitet, minskad översvämningsrisk och grundvattenbildning. En egenskap hos torv som är viktig för dessa funktioner är förmågan att svälla under våta perioder och krympa under torrperioder. Denna torvvolymförändring är relaterad till fluktuationer i grundvattennivå och kan även ha en buffrande effekt på grundvattendjupet (avståndet från markytan till grundvattenytan), vilket påverkar flertalet ekohydrologiska funktioner såsom kolcykling, vegetationssammansättning, och biogeokemiska processer. I ett försök att fylla en lucka i kunskapen kring detta fenomen undersökte detta examensarbete torvvolymförändringar för flera torvmarker, eller myrar, i närheten av Umeå baserat data för grundvattennivåer och nivån på myrars markyta som erhållits under sommaren 2021. Syftet var identifiera trender och egenskaper hos de olika myrarnas förändring i grundvattennivån och myrnivå, samt att ta reda om det finns någon skillnad i torvens kapacitet för att svälla och krypa hos myrar med olika ålder, samt olika markskötsel såsom naturliga, dränerade och restaurerade myrar. Resultatet visade att äldre (äldre än 2000 år) myrar har en betydligt mindre kapacitet att svälla och krympa jämfört med yngre myrar (yngre än 1000 år), samt mindre specifik magasinkoefficient, vilket indikerar att faktorer som förändras när myren blir äldre är viktiga för förmågan att svälla och krympa. Resultatet visade också att förhållandet mellan myrens marknivå och grundvattennivå var linjärt för vissa myrar men inte för andra, inklusive dränerade och gamla myrar. För de dränerade myrarna kunde detta förklaras av mycket djupa grundvattennivåer jämfört med de naturliga myrarna, men de stack inte ut bland de naturliga myrarna vad gäller förmåga att svälla och krympa. Jämförelsen mellan en restaurerad myr och en dränerad gav tvetydiga resultat. Man fann också att den specifika magasinkoefficienten, som är direkt relaterad till torvens kompressabilitet, var större under torra perioder jämfört med våta perioder, vilket visar på myrens förmåga att upprätthålla våta förhållanden. Studien gav en djupare förståelse för myrars förmåga att svälla och krympa och faktorerna relaterade till detta fenomen, vilket är av betydelse för vidare forskning om torvmarkers ekohydrologi.

The phosphatidylinositol 3' kinase (PI3K) pathway is involved in many cellular processes including cell proliferation, survival, and glucose transport, and is implicated in various disease states such as cancer and diabetes. Though there have been numerous studies dissecting the role of PI3K signaling in different cell types and disease models, the mechanism by which PI3K signaling regulates embryonic stem (ES) cell fate remains unclear. It is believed that in addition to proliferation and tumorigenicity, PI3K activity might also be important for self-renewal of ES cells. Paling et al. (2004) reported that the inhibition of PI3K led to a reduction in the ability of leukemia inhibitory factor (LIF) to maintain self-renewal causing cells to differentiate. Studies in our lab have revealed that ES cells completely lacking GSK-3 remain undifferentiated compared to wildtype ES cells. GSK-3 is negatively regulated by PI3K suggesting that PI3K may play a vital role in maintaining pluripotency in ES cells through GSK-3. By using a modified Flp recombinase system, we expressed activated alleles of PDK-1 and PKB to create stable, isogenic ES cell lines to further study the role of the PI3K signaling pathway in stem cell fate determination. In vitro characterization of the transgenic cell lines revealed a strong tendency towards maintenance of pluripotency, and this phenotype was found to be independent of canonical Wnt signal transduction. To assess growth and differentiation capacity in vivo, the ES cell lines were grown as subcutaneous teratomas. The constitutively active PDK-1 and PKB ES cell lines were able to form all three germ layers when grown in this manner – in contrast to ES cells engineered to lack GSK-3. The resulting PI3K pathway activated cells exhibited a higher growth rate which resulted in large teratomas. In summary, PI3K signaling is sufficient to maintain self-renewal and survival of stem cells. Since this pathway is frequently mutationally activated in cancers, its effect on suppressing differentiation may contribute to its oncogenicity.

The phosphatidylinositol 3' kinase (PI3K) pathway is involved in many cellular processes including cell proliferation, survival, and glucose transport, and is implicated in various disease states such as cancer and diabetes. Though there have been numerous studies dissecting the role of PI3K signaling in different cell types and disease models, the mechanism by which PI3K signaling regulates embryonic stem (ES) cell fate remains unclear. It is believed that in addition to proliferation and tumorigenicity, PI3K activity might also be important for self-renewal of ES cells. Paling et al. (2004) reported that the inhibition of PI3K led to a reduction in the ability of leukemia inhibitory factor (LIF) to maintain self-renewal causing cells to differentiate. Studies in our lab have revealed that ES cells completely lacking GSK-3 remain undifferentiated compared to wildtype ES cells. GSK-3 is negatively regulated by PI3K suggesting that PI3K may play a vital role in maintaining pluripotency in ES cells through GSK-3. By using a modified Flp recombinase system, we expressed activated alleles of PDK-1 and PKB to create stable, isogenic ES cell lines to further study the role of the PI3K signaling pathway in stem cell fate determination. In vitro characterization of the transgenic cell lines revealed a strong tendency towards maintenance of pluripotency, and this phenotype was found to be independent of canonical Wnt signal transduction. To assess growth and differentiation capacity in vivo, the ES cell lines were grown as subcutaneous teratomas. The constitutively active PDK-1 and PKB ES cell lines were able to form all three germ layers when grown in this manner – in contrast to ES cells engineered to lack GSK-3. The resulting PI3K pathway activated cells exhibited a higher growth rate which resulted in large teratomas. In summary, PI3K signaling is sufficient to maintain self-renewal and survival of stem cells. Since this pathway is frequently mutationally activated in cancers, its effect on suppressing differentiation may contribute to its oncogenicity.