This thesis offers the first detailed palaeoenvironmental analysis of wetland areas within sub-Arctic enclosed homefield’s. Significance of meadows were previously mentioned only briefly in the literature, suggesting influences in settlement site selection as well as importance in quality fodder production, producing up to two thirds of total hay resources in a somewhat marginal agricultural landscape. Given the importance of hay resources in Iceland it seems unusual these areas have received so little attention to date, despite extensive research on all other aspects of the Norse farm system. The organic sediments within the meadows, given their development in-situ over extended time periods, have the ability to record aspects of the intimate relationship between societal and environmental change, and so in a robust and holistic way our methods set integrates radiocarbon measurement, tephrochronology, palynology and thin section micromorphology from the same core; reflecting these findings against existing paleoclimate and archaeological site data. This combined application of the core techniques – palynology and soil micromorphology, has proven successful in creating effective human ecodynamic records from each of the study farms. Records obtained from the three farm sites in northwest and northern Iceland exposed the varying importance and differing utilisation of these wetland areas. Meadows would appear to have played an import role in choice of settlement site across northern Iceland, through the provision of open areas, and additional and immediately available fodder resources at settlement, in a landscape dominated by dense scrub. Meadows were found to have been in continuous use, albeit at varying levels of intensity, from settlement to the present day. In this respect the semi-natural resources are found to be remarkably resilient, demonstrating little alterations to their composition following severe climatic downturns, including that of the Little Ice Age, and volcanic eruption. Acting as a robust resource and safety buffer for settlements, contributing to fodder resources where reliability of other resources is jeopardised by environmental conditions. Research in the more marginal northwest peninsula provides the first evidence of artificially created wet meadows in Iceland, developed to give sustained fodder production for over-wintering livestock in an environment that inherently had a short growing season and lacked soil fertility. A further example of the nuanced land management practices adopted in the agriculturally fragile farmscapes of the Norse North Atlantic. The findings of the thesis have wider implications for understanding the emergence of resilient and sustainable communities in agriculturally marginal environments; to this end there remains many opportunities to use palaeoenvironmental research to study ecosystem responses to natural and anthropogenic stresses, giving us a better understanding of capacities to withstand future stresses.

Increased nutrient input into wet-meadow ecosystems can affect activity of decomposers and carbon cycle in soil. This thesis observed the effect of fertilization on carbon sequestration and mineralization in soils of wet meadows, which differed in quantity and quality of soil organic matter. Studied locations are situated in the protected area Třeboňsko.

This thesis is an extension of my Bc. thesis. Based upon previously conducted research in a wet grassland, Mokré Louky, near Třeboň, Czech Republic, a mesocosm experiment was designed for investigating the effect of two nutrient regimes (non fertilized / fertilized) and three flooding regimes (saturated / spring flood / flooded) on Carex acuta and Phalaris arundinacea plants to determine the effect of management type for restoring a more diverse wet meadows system.

Nutrient leakage into streams and rivers can lead to eutrophication, which negatively impact aquatic ecosystems. A commonly used tool to mitigate nutrient leakage is the implementation of wetlands into the polluted system. This study focuses on the levels of N and P in the river Fyris.n in Uppsala, Sweden, and the possible effects from restoration of a wetland near the river’s outlet. The results show a potential reduction of 41% and 45% for N and P respectively. The results point to a need for more wetlands further up in the catchment system to mitigate the nutrient load in the subcatchments, as the high nutrient levels there would not be affected by the proposed wetland. There are also several uncertainties due to the lack of reference material, and the results proves the need for further studies on this subject.

Water is a limited and highly valued resource in the semi-arid Great Basin. Surface water sources are often small and widely spaced apart, comprising only 1-3% of the surface area of the overall landscape. Despite their small size, these springs and surrounding wet meadows have a substantial effect on the surrounding environment. Springs provide drinking water, forage and cover for livestock and wildlife, habitat for diversity of plant species and a resource for human-related activities. In recent years, many of these springs have become dewatered due to diversions of groundwater for municipal water and agriculture, and climatic shifts in precipitation affecting recharge. These hydrologic changes can cause a drop in the local water table that promotes a shift in the plant community from wetland-obligates to species that have more drought-tolerance. The root masses of the new plant community are insufficient to secure soils resulting in the erosion of the thalweg. This leads to channelization through the wet meadow, which drives the water table further underground. As degradation progresses, springs and wet meadows lose their ability to store water. The purpose of this thesis is to examine the responses of both the hydrologic and biologic factors to different springbox restoration techniques. Twenty-four spring sites were chosen in the Sheldon National Wildlife Refuge in northwestern Nevada. Each site was randomly assigned one of six different treatment designs. Variables for these studies included: surface soil moisture, soil moisture at varying depths, flow rates, water chemistry, plant community cover and frequency, biomass, wildlife visits and wildlife species numbers. We observed soil moisture increase over the majority of our sites, while flow rates only increased at the control sites. This may indicate that more water is being held in the soils around the spring source instead of being allowed to flow downstream. Biomass increased in four of our six treatments. All treatment types exhibited a similar effect on springs with none having a clearly more restorative effective than any others. This research suggests that springs in the Great Basin have unique characteristics and responses to restoration, and may need individualized approaches. Additionally, studies have shown that it may take many years for plant communities to recover after hydrologic restoration. Yearly variation caused by increased precipitation may be partially responsible for changes in hydrologic and biologic aspects of springs and wet meadows. Further data collection is needed to determine the true extent of treatment and yearly effects on spring restoration. In spite of the need for individualized approaches, restoration is possible. Simple solutions may be sufficient to recover hydrologic processes that maintain ecologic resilience.

No description available.

<h2>BIOGAS POTENTIAL IN GRASSES FROM WETLANDS</h2><p><em>Marvin Martins</em></p><p>The purpose of this study has been to survey wetlands that are suitable for mowing and to analyze the biogas potential in the harvested grasses. A preformed investigation showed that there are suitable wetlands, which can be harvestable, namely those mowed formerly in traditional haymaking. The practice of traditional haymaking is dying out in Sweden today but there are several good reasons why it should to be reconsidered. Nature- and cultural values are obvious, also the unutilized energy in the grass.</p><p>The suitable types of wetland that were specifically studied were the productive wetlands; meadow marshes and wet meadows. These wetlands are represented in the Swedish meadow- and pasture inventory database; (TUVA) and the Swedish national wetland inventory (VMI). Going through the databases showed that they largely complement each other. A geographical mapping was also carried out of wetlands in relation to areas of interest for the future establishment of biogas plants, so called “hotspots”. The geographical survey shows that there is ample amount of grass from wetlands within a 30-kilometer radius that can supplement the plants main substrate, manure. The map layer Swedish Ground Cover Data (SMD) together with GIS software was used to analyze the extent of overgrowth for the older VMI objects in Uppsala County, with the result that half of the VMI objects are no longer of interest. They have become either woodland and bogs, or reed beds.</p><p>There is very little information on wetland-grasses and methane production. Instead, a theory was evaluated regarding the possibility of transforming nutritional values for grass and sedges into biogas potentials. It was shown that this method does not capture the total biogas potential, but offers a minimum value that can be considered rather reliable. The energy transformation showed that late harvested grasses from wetlands has a biogas potential about 0, 21Nm³methane/ (kg, DM) which is about 60 % of the biogas potential for grass-legume forages. The gas yield after 20 days is also relatively low. It could though be favorable to try grasses from wetlands in methane production, because co-digestion with these grasses and other suitable materials could produce a higher net gas yield for the plant, than using the materials solely by themselves. The derived biogas potential showed that there is at least 4, 4 GWh biogas energy in grasses from wetlands in Uppsala county at a low estimate. Harvesting costs were however shown to be too high in the present to achieve a plus result.</p> / <h2>BIOGASPOTENTIAL HOS VÅTMARKSGRÄS</h2><p><em>Marvin Martins</em></p><p>Syftet med detta arbete har varit att kartlägga våtmarker i Biogas Östs region lämpliga att skörda samt att undersöka biogaspotentialen i detta våtmarksgräs. Undersökningen visar att det finns lämpliga våtmarker, så kallade slåtterängar, i den undersökta regionen. Traditionell slåtter är en utdöende företeelse i Sverige men det finns flera goda argument till varför den borde återupptas. Natur- och kulturvärden är givna sådana men även den outnyttjade energin i gräset.<em></em></p><p>Våtmarkstyper som specifikt har studerats är de produktiva våta slåtterängarna; fuktängar, strandängar och mader. Dessa våtmarker finns representerade i Ängs- och betesmarksinventeringens databas; TUVA och våtmarksinventeringens VMI. En genomgång av databaserna visade att de i stor utsträckning kompletterar varandra. En geografisk kartläggning har även utförts på slåttermarker i förhållande till intressanta områden för framtida biogasanläggningar, så kallade ”hotspots”. Kartläggningen visar att det finns gott om våtmarksgräs inom en tremilsradie som kan komplettera anläggningarnas huvudsubstrat, gödsel. Kartskiktet Svenska Marktäckedata (SMD) tillsammans med GIS-programvara har använts för att analysera hur mycket de äldre VMI-objekten i Uppsala län har växt igen, med resultatet att hälften av VMI-våtmarkerna är inaktuella i dagsläget. De har antingen växt igen med mossor och träd eller blivit vassbälten.</p><p>Det finns ytterst begränsat med information kring rötdata på våtmarksgräs. Istället utvärderades en teori, om fodervärden för ett par gräs- och starrarter kan omvandlas till biogaspotentialer. Det visade sig att denna metod inte ger den maximala biogaspotentialen men ett minimivärde erhålls som kan betraktas som ganska tillförlitligt. Energiomvandlingen visar att sent slåttat våtmarksgräs har en biogaspotential runt 0,21 Nm³ metan/(kg, TS) vilket är omkring 60 % av den odlade åkervallens biogaspotential. Gasutbytet efter 20 dagars rötning är också relativt lågt. Trots detta kan det vara fördelaktigt att röta våtmarksgräs, eftersom samrötning mellan detta och annat lämpligt material kan ge ett högre nettogasutbyte för anläggningen än rötning av de enskilda materialen var för sig. Den framtagna biogaspotentialen visar att det finns minst 4,4 GWh biogasenergi i våtmarksgräs från till exempel Uppsala län, lågt räknat. Slåtterkostnaderna har dock visat sig vara för höga för att få det att gå ihop ekonomiskt i dagsläget.</p>

BIOGAS POTENTIAL IN GRASSES FROM WETLANDS Marvin Martins The purpose of this study has been to survey wetlands that are suitable for mowing and to analyze the biogas potential in the harvested grasses. A preformed investigation showed that there are suitable wetlands, which can be harvestable, namely those mowed formerly in traditional haymaking. The practice of traditional haymaking is dying out in Sweden today but there are several good reasons why it should to be reconsidered. Nature- and cultural values are obvious, also the unutilized energy in the grass. The suitable types of wetland that were specifically studied were the productive wetlands; meadow marshes and wet meadows. These wetlands are represented in the Swedish meadow- and pasture inventory database; (TUVA) and the Swedish national wetland inventory (VMI). Going through the databases showed that they largely complement each other. A geographical mapping was also carried out of wetlands in relation to areas of interest for the future establishment of biogas plants, so called “hotspots”. The geographical survey shows that there is ample amount of grass from wetlands within a 30-kilometer radius that can supplement the plants main substrate, manure. The map layer Swedish Ground Cover Data (SMD) together with GIS software was used to analyze the extent of overgrowth for the older VMI objects in Uppsala County, with the result that half of the VMI objects are no longer of interest. They have become either woodland and bogs, or reed beds. There is very little information on wetland-grasses and methane production. Instead, a theory was evaluated regarding the possibility of transforming nutritional values for grass and sedges into biogas potentials. It was shown that this method does not capture the total biogas potential, but offers a minimum value that can be considered rather reliable. The energy transformation showed that late harvested grasses from wetlands has a biogas potential about 0, 21Nm3 methane/ (kg, DM) which is about 60 % of the biogas potential for grass-legume forages. The gas yield after 20 days is also relatively low. It could though be favorable to try grasses from wetlands in methane production, because co-digestion with these grasses and other suitable materials could produce a higher net gas yield for the plant, than using the materials solely by themselves. The derived biogas potential showed that there is at least 4, 4 GWh biogas energy in grasses from wetlands in Uppsala county at a low estimate. Harvesting costs were however shown to be too high in the present to achieve a plus result. / BIOGASPOTENTIAL HOS VÅTMARKSGRÄS Marvin Martins Syftet med detta arbete har varit att kartlägga våtmarker i Biogas Östs region lämpliga att skörda samt att undersöka biogaspotentialen i detta våtmarksgräs. Undersökningen visar att det finns lämpliga våtmarker, så kallade slåtterängar, i den undersökta regionen. Traditionell slåtter är en utdöende företeelse i Sverige men det finns flera goda argument till varför den borde återupptas. Natur- och kulturvärden är givna sådana men även den outnyttjade energin i gräset. Våtmarkstyper som specifikt har studerats är de produktiva våta slåtterängarna; fuktängar, strandängar och mader. Dessa våtmarker finns representerade i Ängs- och betesmarksinventeringens databas; TUVA och våtmarksinventeringens VMI. En genomgång av databaserna visade att de i stor utsträckning kompletterar varandra. En geografisk kartläggning har även utförts på slåttermarker i förhållande till intressanta områden för framtida biogasanläggningar, så kallade ”hotspots”. Kartläggningen visar att det finns gott om våtmarksgräs inom en tremilsradie som kan komplettera anläggningarnas huvudsubstrat, gödsel. Kartskiktet Svenska Marktäckedata (SMD) tillsammans med GIS-programvara har använts för att analysera hur mycket de äldre VMI-objekten i Uppsala län har växt igen, med resultatet att hälften av VMI-våtmarkerna är inaktuella i dagsläget. De har antingen växt igen med mossor och träd eller blivit vassbälten. Det finns ytterst begränsat med information kring rötdata på våtmarksgräs. Istället utvärderades en teori, om fodervärden för ett par gräs- och starrarter kan omvandlas till biogaspotentialer. Det visade sig att denna metod inte ger den maximala biogaspotentialen men ett minimivärde erhålls som kan betraktas som ganska tillförlitligt. Energiomvandlingen visar att sent slåttat våtmarksgräs har en biogaspotential runt 0,21 Nm3 metan/(kg, TS) vilket är omkring 60 % av den odlade åkervallens biogaspotential. Gasutbytet efter 20 dagars rötning är också relativt lågt. Trots detta kan det vara fördelaktigt att röta våtmarksgräs, eftersom samrötning mellan detta och annat lämpligt material kan ge ett högre nettogasutbyte för anläggningen än rötning av de enskilda materialen var för sig. Den framtagna biogaspotentialen visar att det finns minst 4,4 GWh biogasenergi i våtmarksgräs från till exempel Uppsala län, lågt räknat. Slåtterkostnaderna har dock visat sig vara för höga för att få det att gå ihop ekonomiskt i dagsläget.