| 1. |
- Axelsson, Josefine, 1992-
(författare)
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Interglacial climates in proxies and models : Utilizing sampled oxygen isotopes and model simulations to understand past Indian summer monsoon variability
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The study of Earth's climate system, including the mechanisms driving monsoon systems, is a key area of research within environmental sciences. Monsoons, vital for billions of people, are complex atmospheric phenomena influenced by various global factors, including orbital changes and natural climate variability. Among monsoon systems, the Indian summer Monsoon (ISM) is of particular interest due to its significant impact on the South Asian climate, agriculture, and water resources. Despite extensive study, comprehending the ISM's historical variability and its future implications remains a challenge. Utilizing natural archives like speleothems, along with stable water isotopes from precipitation and advanced climate model simulations, this thesis aims to decipher the ISM's responses to natural forcings across key interglacial periods—the Last Interglacial and the Holocene.Our findings indicate that the ISM's strength is critically influenced by slight variations in orbital configurations, leading to significant shifts in monsoon patterns. Our research also highlights the dual influence of local geographical features and distant atmospheric conditions on the ISM's annual variability. Most notably, we observed discrepancies between δ18O values obtained from isotope-enabled climate models and those derived from speleothems. This insight indicates that the models need refinement to accurately mirror the complexities observed in the proxy records and that the uncertainty parameter in speleothem records needs to be improved.The alignment between proxy and model data is crucial for a more accurate reconstruction of past climates and for enhancing the predictive capabilities of future monsoon behavior under changing climatic conditions. By advancing our knowledge of the ISM's past, we are better equipped to anticipate its future. To achieve that, this thesis stresses the importance of bridging the gap between proxy data insights and climate model simulations. This would not only enrich our historical climate knowledge but also inform future climate projections, highlighting the indispensable role of interdisciplinary research in climate science challenges.
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| 2. |
- Bennich, Therese, 1989-
(författare)
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The transition to a bio-based economy : Toward an integrated understanding
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The bio-based economy has gained increasing attention in societal and academic debates over the past two decades, and is argued to hold solutions to several pressing sustainability challenges. However, it is not yet clear if the high-reaching aspirations of the bio-based economy can be realized. The bio-based economy discourse has been criticized for being promissory, vague, and single-sector focused, thereby overlooking larger systemic impacts, trade-offs, and unintended consequences that may result from pursuing the goals of the bio-based economy. Against this background, this thesis aims to advance an integrated and systemic understanding of the transition to a bio-based economy and what it implies for sustainability. Sweden is used as an empirical case, where specific bio-based economy goals, as well as their interactions and sustainability outcomes, are examined. The focus is primarily on developments in the forestry, agriculture, and energy sectors. The analysis also seeks to identify how goals related to the bio-based economy are interconnected with goals promoted by parallel sustainability initiatives, specifically the 2030 Agenda and the associated Sustainable Development Goals (SDGs). Integration is achieved by using systems analysis tools and methods. Further, the weak and strong sustainability paradigms, and the opposing definitions of sustainability they provide, are used to assess the contribution of the bio-based economy to sustainability. The integrated analysis provides a detailed and operational conceptualization of transition pathways to a Swedish bio-based economy. The goals of the Swedish bio-based economy are divergent and broad-reaching, emphasizing that there is no general agreement on what the transition to a bio-based economy entails. The results point to multiple barriers that need to be addressed to realize the goals of the Swedish bio-based economy. Goal conflicts constitute one such barrier. These are found internal to as well as across the bio-based economy and the parallel 2030 Agenda. Additional hindrances include policy resistance, negative cross-sectoral spillovers, and patterns of path dependency. However, the results also highlight several opportunities for supporting the transition process in a Swedish context. These opportunities include the identification of goals and interventions with synergetic potential, which offer a basis for developing efficient implementation strategies with high systemic impact. There is also large potential to support cross-sectoral collaboration and learning, based on shared interests and challenges. Finally, the results emphasize the importance of better understanding and addressing perceptions about risk, conflict, legitimacy, and trust in the transition process.In terms of the overarching question of what the bio-based economy implies for sustainability, the results find that the bio-based economy has been contributing to developments that align primarily with weak sustainability. From the perspective of the strong sustainability paradigm, the prospects of the bio-based economy are less promising, potentially leading to outcomes that could worsen ongoing environmental and social issues. For the future, fundamental changes to the way the bio-based economy is conceptualized and implemented are needed for it to contribute to sustainability according to the notion of strong sustainability.
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| 3. |
- Berntell, Ellen, 1989-
(författare)
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Understanding West African Monsoon Variability : Insights from Paleoclimate Modelling of Past Warm Climates
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Sahel, a water-vulnerable region in West Africa, relies heavily on rainfed agriculture. The region experienced pronounced droughts during the 20th Century, emphasising the socio-economic importance of understanding the drivers of the rainfall variability. However, future rainfall projections remain uncertain due to the complex nature of the West African Monsoon (WAM), which is influenced by internal climate variability, external forcing, and feedback processes. Limited observational records in West Africa and the need for longer time series further complicate the understanding of these drivers. This thesis uses paleoclimate modelling to investigate internal and external drivers of monsoon variability in West Africa across four distinct periods. Our study confirms that atmosphere-only model simulations can capture the observed multidecadal rainfall variability in the 20th Century, even though reanalyses struggle to reproduce the correct timing. Analysis of a last millennium simulation using the Earth System Model EC-Earth3 identified two drivers of multidecadal rainfall variability, accounting for 90% of the total co-variability between the West African rainfall and Atlantic sea surface temperatures (SSTs). This finding strengthens our understanding of SST-WAM relationships observed during the 20th Century. An ensemble of climate model simulations (PlioMIP2) shows that high CO2 levels and a different paleogeography during the mid-Pliocene Warm Period led to increased rainfall and a strengthened WAM. Our study emphasised vegetation's crucial role in enhancing the monsoon in past climates. However, simulations forced with prescribed vegetation only capture a one-directional forcing. A mid-Holocene simulation using an Earth System Model with dynamic vegetation revealed that vegetation feedbacks strengthen the WAM response to external orbital forcing but are insufficient to shift the monsoon northward or increase vegetation cover over the Sahara. These results reveal a dry bias and under-representation of simulated vegetation compared to proxy records, highlighting the importance of model development and the need for additional feedback processes in driving an enhanced, northward WAM and extending vegetation to the Sahara. Overall, this thesis advances our understanding of the drivers of West African monsoon variability and provides valuable insights for improving future rainfall projections in this vulnerable region.
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| 4. |
- Chakrawal, Arjun, 1992-
(författare)
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Novel approaches in modeling of soil carbon : Upscaling theories and energetics
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soils contain more carbon (C) than terrestrial (above ground) and atmospheric carbon combined. Mismanagement of soil C could lead to increased greenhouse gas emissions, whereas practices leading to increased C storage would help mitigate climate change while improving soil fertility and ecological functions. At the center of these complex feedbacks, soil microorganisms play a pivotal role in the cycling of C and nutrients, and thus in soil-climate interactions. However, this role is not fully understood; therefore, developing new methods for studying their dynamics is essential for an understanding of bio-physicochemical processes leading to mineralization or stabilization of soil organic matter (SOM).Current soil C cycling models lack a robust upscaling approach that links SOM decomposition from process (μm) to observation scale (cm to km). Moreover, these models often neglect energy fluxes from microbial metabolism, which may provide additional constraints in model parameterization and alternative observable quantities such as heat dissipation rate to study decomposition processes. In this doctoral work, I investigated two aspects of microbial processes and their consequences for SOM dynamics: 1) use of energetics to constrain SOM dynamics by explicitly accounting for thermodynamics of microbial growth, and 2) spatial constraints at microscale resulting from the non-uniform distribution of microorganisms and substrates.In the first part of the thesis, I developed a general mass and energy balance framework for the uptake of added substrates and native SOM. This framework provided the theoretical underpinnings for understanding variations in the calorespirometric ratios—the ratio of rates of heat dissipation to CO2 production—a useful metric used as a proxy for microbial carbon-use efficiency (CUE). Moreover, in a follow-up work, I extended this mass-energy framework to describe dynamic (time-varying) conditions, which was used to interpret rates of heat and CO2 evolution from different soils amended with glucose. The dynamic mass-energy framework was also used as a tool for data-model integration and estimation of microbial functional traits, such as their CUE and maximum substrate uptake rates. In the second part of the thesis, I linked the micro and macroscale dynamics of decomposition using scale transition theory. The findings of this study were further validated from laboratory experiments, in which spatial heterogeneity in the added substrate was manipulated.Results from the first part show that the calorespirometric ratios can be used to identify active metabolic pathways and to estimate CUE. Further, the heat dissipation rate can be used as a reliable complement or alternative to mass fluxes such as respiration rates for estimating microbial traits and constraining model parameters. In the second part, I show that the co-location of microorganisms and substrates increased, and separation decreased the microbial activity measured as heat dissipation from the incubation experiment. These results were in line with the expectation from the scale transition theory. In summary, this work provides novel approaches for studying soil C cycling and explicitly highlights a way forward to address two fundamental issues in microbial decomposition—the role of spatial heterogeneities and of energetic constraints on microbial metabolisms.
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| 5. |
- Guasconi, Daniela, 1992-
(författare)
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The hidden half of the meadow : Interactions between drought, soil carbon, roots and soil microbial communities
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Soil is a hidden ecosystem which harbours plant roots and countless microorganisms, vital for sustaining life aboveground. These belowground communities provide essential ecosystem services like soil stabilisation and organic matter decomposition. Soil is also one of the largest terrestrial carbon repositories, and land management strategies aimed at increasing organic matter inputs from plants, such as compost additions, can promote further soil carbon accumulation. Because organic carbon is important for soil water retention, this management may also help to increase resilience against more frequent and intense droughts. Although roots and microbial communities are largely acknowledged to play a key role in regulating the carbon cycle, there are still many open questions regarding the link between above- and belowground processes and ecosystem functions. Observing climate- and management-driven changes in the soil habitat is fundamental for understanding how ecosystems respond to environmental change.The aim of this thesis is to explore the relationship between soil properties, plant communities, and soil microbial communities in response to environmental changes. The research builds on a meta-analysis of drought effects on grasslands, and a multifactorial field experiment which combined three years of precipitation reduction and a compost treatment in two Swedish grasslands. We analysed the response of roots and soil microbial communities to drought and compost amendments, and identified environmental factors behind their large spatial variability. Finally, we tested the effects of compost additions on soil carbon storage and its interactions with drought.The results of the meta-analysis indicate that, on a global scale, grassland roots and shoots have diverging responses to drought duration and intensity, with long-term climate mediating that difference. At the local scale assessed in the field experiment, we observed that the spatial patterns of soil microbial communities were driven by soil properties and vegetation. Growing season drought affected roots only at trait level, but did not significantly affect microbial communities. Positive effects of compost on aboveground plant productivity and fungal growth were detectable after three years. Compost amendments also increased the percentage of total soil carbon, but no net increase in soil carbon stocks was detected. Spatial variability in roots and microbial communities was larger than the treatment effects, and was important in shaping microbial community composition and determining grassland responses to drought.Taken together, these findings suggest that roots and microbial communities are likely to be tolerant to drought a within the timescale of this experiment, but we did not observe an increase soil carbon sequestration or drought resilience when adding compost. This thesis highlights the importance of considering soil processes as complementary to aboveground observations when studying carbon dynamics, predicting ecosystem responses to environmental change, and developing sustainable land management practices.
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| 6. |
- Holmes, Felicity Alice, 1995-
(författare)
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Glacier-Ocean Interactions in the Arctic : Contemporary calving and frontal melt from field observations, remote sensing, and numerical modelling
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Globally, glaciers are losing mass as a result of the changing climate, with this mass loss having a considerable societal impact through rising sea levels. Glaciers which terminate in the oceans are particularly vulnerable to changing external conditions as a result of high sensitivity at their marine margins. Both changing meteorological patterns as well as changing ocean heat content and transport have been previously identified as potential drivers for contemporary rapid glacier retreat and acceleration. However, uncertainties remain and provide motivation for studies which improve our process understanding. Here, we use a combination of field data, remotely sensed data, and targeted numerical modelling experiments to investigate marine terminating glacier response to external changes. This is done in order to address uncertainties around mass loss at the inaccessible glacier-ocean interface. In particular, focus is paid to the processes of submarine melt and calving, together referred to as frontal ablation. Submarine melt is the melting of glacier termini by warm ocean waters below the waterline, whilst calving is the breaking off of icebergs from glacier termini. The two processes are interlinked, with submarine melting undercutting the glacier terminus and contributing to calving, whilst calving events can expose larger areas of the glacier margin to submarine melt. To look for relationships between frontal ablation and external forcings, four glacier-fjord systems were studied to varying extents; two grounded glaciers in Svalbard (Kronebreen and Tunabreen) and two glaciers with floating ice tongues in Greenland (Ryder glacier and Petermann glacier). Both submarine melt and calving were examined at various different scales, both temporally and spatially. Specifically, analysis was carried out from the scale of individual calving events up to decadal long time series of glacier margin change. Much of the data used focused on specific glaciological variables such as satellite-derived velocities, margin positions, model simulations, and time-lapse photography of calving events. However, as glaciers and their adjacent fjord or ocean environments impact on each other, data such as water temperatures were also collected from glacier proximal fjord environments. The results from both the observational data and model experiments suggest that ocean temperatures are of great importance for the frontal ablation of glaciers in the Arctic, but that the relationship is complex. Heterogeneous glacier response to external forcings highlights how site specific factors such as bathymetry and fjord geometry can add an additional layer of complexity and make it challenging to scale up results from one glacier to an entire region. However, there are some strong indications that it is the presence of warm air temperatures in conjunction with warm ocean temperatures that is most important for driving frontal ablation - highlighting the need to situate glacier behaviour within a wider environmental context.
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| 7. |
- Kapás, Rozália E., 1988-
(författare)
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Grassland restoration : Connectivity, plant community change and cows
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ecological significance of semi-natural grasslands is high because these habitats provide a home for a diverse flora and fauna and support a range of associated ecosystem services. Due to large-scale land-use changes the extent of grassland habitat has declined. Hence, restoration efforts to mitigate grassland losses are now being prioritized across the globe and there is an increasing need to understand the drivers behind the recovery of degraded habitats. Since many restoration initiatives rely on spontaneous dispersal of plant species from sources at both local- and landscape-scales, community assembly is influenced by a range of factors which interact both over time and across spatial scales. Given this complexity over the scales, gaps remain in our understanding of how post-restoration management can be designed to facilitate the effective dispersal and establishment of target species in restored grasslands.In this thesis, I examined colonization patterns in Swedish grasslands by comparing plant communities in both ancient and restored grasslands and under contrasting management regimes. At small spatial scales and over the short-term following restoration, I investigated species recruitment sources and their relative contribution to colonization and regeneration. At larger temporal and spatial scales, I examined how the composition of vegetation and seed bank communities is determined by local environmental factors together with distance to species pool and presence of grazing livestock.I found that species mostly colonized spatially from local species sources through seed rain. The seed bank contributed to species colonization to a greater extent in ancient grasslands than in restored grasslands. Management through livestock grazing and shorter distance to species pool were positively associated with the number of species found in grasslands. Grazing livestock facilitated target species establishment into restored sites and the differences between ancient and restored grassland communities were smaller when grazing was active, highlighting that ancient sites can provide a source of colonizing species for restored sites. I found that plant species associated with former land-use declined immediately following restoration, while the occurrence of target species generally increased. However, there was a high initial stochasticity in the establishment of the target species and communities in restored grasslands were still distinct from continuously managed sites even after several decades.These results demonstrate that species presence in nearby ancient grasslands and potential dispersal from the local seed sources drives species colonization in restored and ancient grasslands. Livestock grazing was shown to be an important driver of grassland recovery, either by mediating spatial dispersal of seeds or improving site conditions for establishment. Target species are able to accumulate in the vegetation and seed bank over the long-term, as restored grasslands age. This accumulation will ensure an increasing resilience of grassland communities against future disturbances or changes in the climate. However this depends upon active management, for example by implementing management plans which include continued livestock grazing, and upon conserving remaining ancient grasslands as hotspots for biodiversity within the wider landscape.
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| 8. |
- Katrantsiotis, Christos, 1982-
(författare)
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Holocene environmental changes and climate variability in the Eastern Mediterranean : Multiproxy sediment records from the Peloponnese peninsula, SW Greece
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents multiproxy reconstructions of the mid to late Holocene climate and environmental changes in the Peloponnese peninsula, SW Greece. The combined dataset consists of diatom, biomarker and X-ray fluorescence spectrometry (XRF) elemental data in radiocarbon-dated sediment cores taken from the Agios Floros fen and the Gialova Lagoon in SW Peloponnese and the Ancient Lake Lerna in NE Peloponnese. Overall, the results highlight the complex interaction between climate, tectonics and human activities in the landscape development and further reveal changes in the W-E precipitation/temperature gradient over the peninsula connected to shifts in the large-scale atmospheric circulation patterns.The Agios Floros study provides a 6000-year hydrological record based on diatoms and hydrogen isotopic (δD) analysis of aquatic plant-derived n-C23 alkanes. The records indicate two decadal-long periods of deep water conditions at ca 5700 and 5300 cal BP, largely attributed to local tectonic processes and the hydrological anomalies of the nearby karst springs. A period of intermediate water level at ca 4600 cal BP is dominated by the new fossil species Cyclotella paradistinguenda described in this thesis. The gradual development of a fen at ca 4500 cal BP is attributed to a combination of human activities and drier conditions, the latter culminating in SW Peloponnese mainly after ca 4100 cal BP. From ca 2800 cal BP and onwards, there is evidence for flooding events probably related to marked rainfall seasonality.The n-alkane δD profiles and XRF data analyzed in the Gialova core co-vary with each other indicating a common climate signal during the last 3600 years, which resembles the Agios Floros record. The n-alkane δ13C values show high contribution of aquatic vegetation to sedimentary organic matter during wet/cold periods. The n-alkane δD signals from the Lake Lerna also exhibit a similar pattern to each other providing further evidence for precipitation/temperature changes over the last 5000 years.Comparison of the δD records reveals sometimes similar and sometimes opposing signals between NE and SW Peloponnese, which can be attributed to the relative dominance of high latitude and low latitude atmospheric patterns over the peninsula. The records show wet conditions at ca 5000-4600 cal BP likely associated with the weakening of the Hadley circulation. High humidity is also evident at ca 4500-4100, ca 3000-2600 (more unstable in SW) and after ca 700 cal BP with drier conditions at ca 4100-3900 and ca 1000-700 cal BP. These periods correspond to regional climate changes, when the North Atlantic Oscillation (NAO) likely exerted the main control with NAO (+) creating conditions of reduced moisture. A NE-SW climate see-saw with drier conditions in NE Peloponnese is evident at ca 4600-4500, ca 3200, ca 2600-1800 and ca 1200-1000 cal BP and a reversal at ca 3900-3300 ca 3200-3000 and ca 1800-1300 cal BP. The dipole pattern is likely driven by shifts in the North Sea–Caspian Atmospheric pattern (NCP), with NCP (+) leading to wetter and colder conditions in NE Peloponnese. The opposing signal can also be explained by changes in summer temperatures driven by the Asian monsoon intensity. Strong monsoonal periods coincide with cool summers in Lerna, due to the northerly winds (Etesians), in contrast to SW Peloponnese, located on the lee side of the mountain and most affected by the large-scale air subsidence.
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| 9. |
- Ketzer, Daniel, 1988-
(författare)
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Land Use Conflicts between Agriculture and Energy Production : Systems Approaches to Allocate Potentials for Bioenergy and Agrophotovoltaics
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The developments towards a bio-based economy and a renewable energy-based power supply require thorough assessments of feedstocks and frameworks. In the past, political targets for increasing shares of renewable energies for combatting climate change have triggered direct land use changes (LUCs) and even indirect land use changes (iLUCs). As a consequence, residues from grassland and agriculture, which are not used for other purposes, got into the focus of renewable energy policies. Despite the technical feasibility, a general approach for assessing amounts of residues has been lacking, making planning processes for bioenergy highly customized. This study introduces a general, uniform modeling-approach based on Geographic Information Systems (GIS) and publicly available statistical and map data to locate potentials on a 1 km-grid throughout the European Union (EU). Sustainable potentials were calculated for five model regions in Northwest Europe considering input data such as animal livestock, regional (elevation-dependent) yield data, protection areas, and residue-to-crop ratios. Framing two scenarios, the model results were fed into a Decision Support Tool (DST) as a planning tool for bioenergy. Agricultural residues and surplus grass may provide significant potentials on regional levels, e.g. up to 52,236 TJ/ a from straw and 1,301 TJ/ a from root crop residues in Northrhine-Westphalia, or 9,141 TJ/ a from oil plant residues in Île de France, and 12,226 TJ of surplus grass in Rhineland-Palatinate.At the same time, ground mounted PV-systems were installed on arable land formerly used for food or feed production. Hence, high quality soils were taken out of agricultural production. For addressing this type of conflict, Agrophotovoltaic (APV) systems combine agricultural biomass and solar power production on the same site and time for increasing area use efficiency. Even though APV might prove suitable in the technical sense, it might be rejected by society i.e. due to its landscape impact. The Responsible Research and Innovation (RRI)-concept was applied for APV by involving stakeholders already in the technology development process. In a series of workshops with citizens and experts, a comprehensive analysis of the driving and restraining forces for APV was done. A System Dynamics approach with Causal Loop Diagrams (CLD) visualizes and reveals the internal and external dynamics of the APV-technology. Stakeholders have pointed out the importance of defining a good framework for APV first, i.e. roof and industrial areas for PV system shall be exploited first. Any change in the set-up for the PV-system impacts the conditions for the agricultural cultivation conditions, i.e. the height and width of the mounting system influences the working conditions and distribution of water. The shading of the plants can increase the yields in dry and hot summers, while it may lead to yield reductions in other years. The acceptance level is driven by regional aspects such as tourism, local recreation and landscape impact. In this way, local knowledge from participatory studies is seen as prerequisite for a legitimate framework.
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| 10. |
- Larsson, Simon A., 1990-
(författare)
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Ashes to ashes : Applications of tephrochronology in Scandinavia
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The project presented in this thesis provides two examples of applications of tephrochronology in Scandinavia. The usage of tephra deposits preserved in sediments—i.e. horizons of volcanic ashes, detected either as visible layers or as low-concentration “cryptotephras”—is demonstrated to be a strong and versatile tool for chronological control of individual sediment sequences and for correlation between study sites on both local and wider-regional scales.Fieldwork was done at a number of study sites in southernmost Sweden and mid-Norway to sample sediments formed in lakes and peatlands during the Last Glacial–Interglacial Transition, i.e. c. 16,000–8,000 years ago. Labwork was then performed to analyse the sediments by methods to estimate organic matter, organic and carbonate carbon, and elemental contents as well as to find datable macrofossils and to detect tephra occurrences. Among the detected tephras between the different study sites, identifications were made of the Fosen Tephra, the Hässeldalen Tephra, the Vedde Ash, and the Laacher See Tephra. These were used for the purposes of either application in the project; (1) a palaeoclimate reconstruction at Körslättamossen, with new proxy analyses and correlations to a previous study of the same site as well as to other studies in Europe via linkages established by the tephras, and (2) a palaeoglaciological reconstruction on the Fosen peninsula, based on correlations between study sites using the detected tephras to assess the timing of glacial retreat in the area.The palaeoclimate reconstruction at Körslättamossen and correlation to previous studies provides new information about the climatic development in Europe after the end of the last ice age, specifically regarding the timing of the cold stage known as the Younger Dryas. Detailed knowledge of such events, spatially and temporally, is necessary to understand the behaviour of the climate system in the past and, thereby, its behaviour in the present and the future. This is one of several studies demonstrating the usefulness of tephrochronology for such research questions.The palaeoglaciological reconstruction on the Fosen peninsula, also relating to the Younger Dryas, is one of a few recent studies which demonstrate the strengths of tephra investigations in providing evidence for the timing of events on more local scales than the wider spatial perspective more often utilised in tephrochronological applications. Other than resulting in a significantly revised chronology for the retreat of the Scandinavian Ice Sheet in the study area, this study should also encourage new, similar tephra studies in future Quaternary research.In addition to the direct results of either study (mainly presented in the related scientific papers) and the addition of new reference data for later tephra studies, the thesis also discusses further implications of the results and observations made with emphasis on considerations and study design issues in Quaternary research at large and for the tephrochronologist in particular.
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| 11. |
- Livsey, John, 1983-
(författare)
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Sustainable agriculture : From global challenges to local land management
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite the success of agriculture management practices in increasing the availability of food needed to meet the requirements of the expanding global population, there are increasing demands placed on the resources on which the sector depends. Opportunities for the development of agricultural systems are constrained by increasing competition, from other sectors, for shared resources. In tackling this constraint, agricultural management solutions are often narrowly focused on problems related to single resources. But this single focus may lead to unintended trade-offs. To make sound management decisions, there is a need to better understand trade-offs which may occur from resource use efficiency solutions implemented in the agricultural sector. With a particular focus on soil and water resources, the aim of this thesis was to investigate trade-offs that occur, when meeting demands placed on agriculture systems, if management solutions are narrowly focused. Broadly, we hypothesize that approaches to land management that take a more holistic view of agricultural systems being part of an ecosystem mosaic should be adopted to ensure sustainability. A global assessment of potential land requirements shows that national level production of sufficiently nutritious food may be constrained by land availability, such that allocation of land to nutritious crop production might come at the cost of lost land for other crops or uses. This constraint will be the most prevalent in African states. In further studies, we focused on the management of water resources, which are becoming particularly limiting for crops that have high water demands, such as rice. Through a meta-analysis of paired plot experiments, which assessed the effect of water saving irrigation in rice production, and soil sampling within An Giang, a major rice producing province of Vietnam, we examined the effect of water management practices on soil properties. The meta-analysis finds that significant reductions in soil organic carbon, and potentially organic matter bound nutrients, have been observed when water efficient practices replace continual flood irrigation. This suggests that, although yield reductions may not be seen in the short term, water saving irrigation may, over time, lead to reductions in soil fertility and yields. Within An Giang province, there are concerns regarding the loss of flood-borne, nutrient rich, sediments in fields where the annual flood waters have been completely regulated. However, we find that this complete regulation does not result in reduced soil nutrient properties when compared to areas where floods are only partially regulated. The effect of different land management practices on soil properties were further explored within the Kilombero Valley, Tanzania. Comparing farming practices along a gradient of intensity, we found contrasting effects of irrigation and fertilization, with irrigation increasing soil organic carbon and fertilization reducing soil organic carbon. Overall, the results of this thesis highlight the importance of looking beyond meeting short term needs, which can have negative long term consequences. The success of land management practices implemented now do not, necessarily, equate to their continued success in the future. As demands placed on agriculture are going to increase, the long term trade-offs which may occur from present practices must be at the forefront of agricultural management.
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| 12. |
- Maneas, Georgios, 1980-
(författare)
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Towards co-management of Gialova Lagoon : A Natura 2000 coastal wetland in Messinia, Greece
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The management of Natura 2000 sites is considered as the cornerstone for the conservation and restoration of biodiversity within Europe. However, protected ecosystems provide a plethora of benefits to local societies, and support the local economy. Thus, to seek solutions for complex environmental issues within Natura 2000 sties it is imperative to approach the site of concern as a connected social-ecological system, and to strengthen the participation of stakeholders in decision-making following a co-management approach.Gialova Lagoon wetland, in Messinia, Greece represents an example of Natura 2000 site which needs to be managed. The overall aim of the PhD thesis was to assess the problem of lagoon salinization, and provide policy recommendations for wetland restoration and management of associated freshwater resources under a changing climate. The thesis has followed a social-ecological approach, by integrating DPSIR framework with participatory Systems Dynamic modelling and the concept of ecosystem services. Knowledge gaps about major social and ecological components were assessed by applying a variety of methods, namely (a) field monitoring and observations, (b) GIS analyses, (c) consultation with stakeholders, (d) modelling and scenarios.The thesis results suggested that past human interventions had multi-fold effects on the Gialova Lagoon wetland, namely hydrology alteration, ecosystem fragmentation, loss and transformation of natural habitats. Furthermore, the combined effects of alterations in hydrology and climate change have led to increased salinity in the wetland over time. These alterations had profound implications on wetland ecosystem services such as the diversity of habitats and waterbirds and the provision of fish. Under contemporary hydrological connectivity and on-going climatic conditions, the mean annual salinity of the lagoon has increased from approximately 35 g/L during the period 2016-2018 to approximately 40 g/L during the period 2021-2023 indicating a salinization increase of approximately 1 g/L per year. To identify restoration alternatives, the work under the PhD thesis has engaged scientists with local stakeholders from the sectors of agriculture, fishing, tourism, and public administration, in a co-management approach. The end product, an SDM (Systems-Dynamics model) co-created with stakeholders, was suitable for exploring scenarios for salinity regulation and management of associated freshwater resources, under a changing climate (RCP 4.5). The derived management suggestions, namely restoration of the connectivity with the surrounding freshwater bodies (river, artesian springs) and between habitats (e.g., lagoon-marshes), could result in the de-salinization of the lagoon within a 10-year period, and could be applied within the Natura 2000 framework as they consider social and ecological needs (e.g. enhancement of biodiversity and fish production). However, under current abstraction rates for irrigation and municipal water-supply, there is a high risk of groundwater scarcity during years with dry conditions, and thus investments in water-saving technologies (e.g. smart irrigation) should be promoted to ensure adequate water availability for restoration, and enhanced resilience of the local economy against groundwater scarcity.
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| 13. |
- Mas e Braga, Martim, 1991-
(författare)
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Modelling ice surface elevation changes in Dronning Maud Land, East Antarctica : Bridging the gap between in-situ and numerical model reconstructions
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ice sheets are an active component of Earth's climate system. Their topography influences atmospheric circulation and changes in their volume alters freshwater fluxes to the oceans, affecting ocean water masses, atmospheric carbon uptake, and global sea level. Sea-level rise has a marked societal impact, and thus ice sheet models are indispensable tools to predict it. To increase confidence on sea-level rise projections, it is necessary that ice sheet models accurately represent the relevant processes governing ice sheet dynamics. Given the fact that ice sheets respond to geological-scale changes in Earth's system, it is necessary that their performance is compared with in-situ data of past geological periods, which are discrete in space and time. One useful constraint used for validating model results is past ice surface elevation, which is reconstructed based on rock samples taken from nunataks (mountain summits that pierce through the ice sheet surface). However, two main problems prevent reliable comparisons of past ice surface elevations between model and empirical results. First, data-model comparisons are hindered by the fact that most large-scale ice sheet models capture neither the timing nor the magnitude of ice thinning reconstructed for the last deglaciation. Second, the complex subglacial topography of regions where nunataks are present is also reflected on the ice sheet surface, through pronounced elevation gradients. As a result, the choice of a reference point on the present-day ice sheet, which can be subjective, is a significant source of uncertainty when computing thickness-change estimates. In this thesis, I aim to reconstruct changes in ice sheet geometry over Dronning Maud Land (DML, East Antarctica) during periods that were warmer and colder than present, and the climate drivers behind such changes. I assess whether the comparison between empirical and model results can be improved by resolving local features in ice sheet models, and by using data and models in an iterative way (using data to constrain the model, and models to interpret the data). The results of this thesis demonstrate that ice flow in areas of complex topography is poorly resolved in continental-scale ice sheet models and requires modelling in high resolution to match results from empirical constraints. High-resolution ice-sheet models, in turn, show that accurate ice sheet surface elevation reconstructions from empirical data require systematic sampling and definition of reference points over the modern ice sheet surface. Moreover, a consistent reconstruction of regional ice-thickness changes needs both empirical and ice sheet model results. Based on constrained models and empirical datasets, the ice sheet in DML responds to an interplay between sea level, ocean warming, surface mass balance, and subglacial topography. Samples from nunataks mainly reflect local ice surface elevation changes, potentially missing catchment-scale (regional) changes. Accurately determining regional changes using high-resolution modelling plays a significant role when interpreting the evolution of ice streams. Hence, the work presented here highlights that accurately reconstructing past ice sheet geometry is an effort that can only be truly successful if field scientists and ice sheet modellers work in tandem, at experiment-design, sampling, and result-interpretation stages.
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| 14. |
- Mulokozi, Deogratias, 1986-
(författare)
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Integrated Agriculture and Aquaculture Systems (IAA) for Enhanced Food Production and Income Diversification in Tanzania
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aquaculture production in Tanzania has increased in recent years, responding to an increased demand for fish, partly because of an increasing population and declining catches of wild fish. However, the current aquaculture production is still low, dominated by small scale farming systems, that are struggling with a number of challenges such as lack of improved fish breeds, feeds, technical skills and low adoption rates.This thesis aims to assess the status of fish pond farming with a focus on integrated agriculture and aquaculture (IAA) systems in Tanzania, and to provide guidance on how these systems could be further developed to help local farmers to diversify their food production and income generation.Methodologies included field observations, interviews, structured questionnaires, field experiments and laboratory analyses. Two field surveys in six districts and seven regions of Tanzania provided insights on the current status and the contribution of small-scale pond farming and IAA to household income and food production. Differences between IAA and non-IAA fish farming practices, and their influence on farm productivity and profitability were assessed. Also, opportunities, constraints and farmers’ future plans for fish farming were explored. Two field experiments were conducted on selected IAA systems identified during the surveys. One assessed the effect of including amaranth (Amaranthus hybridus) waste in locally produced fish feed on the yield of Nile tilapia (Oreochromis niloticus). Another investigated how the combination of different vegetables (A. hybridus and Brassica rapa pekinensis) and stocking densities of O. niloticus affected the water use efficiency, need for synthetic fertilizers and overall farm productivity and profitability.The results show that small scale fish farming contributed with 13% of the farmers’ income. 38% of the fish was used for consumption and the remaining part was sold, contributing to both food security and livelihood diversification. Integration of tilapia and vegetables was the most common type of IAA system applied. Local feed ingredients contained medium to high content of crude protein, with high fat content in some animal by-products. The fish yield from the IAA ponds was 60% higher compared to non-IAA ponds because of a more frequent use of on-farm resources and better management. The net income from IAA ponds was 175% higher compared to non-IAA ponds, due to reduced costs and higher yields. Major constraints included water problems, lack of technical skills and good quality fish seeds and feeds. Overall, fish farmers had a positive attitude towards fish farming and the majority were willing to continue with fish farming, with IAA farmers being more positive than non-IAA farmers. The use of amaranth wastes as a fish feed ingredient in a tilapia-amaranth integrated system did not affect the fish growth and yield, but rather improved the feed conversion ratio. The multiple use of water in integrated tilapia-vegetable systems increased the water use efficiency and reduced the need for synthetic fertilizers. Although water from high fish stocking densities increased the vegetable yield, the overall farm productivity in the IAA system was negatively affected because of low fish growth and survival rates. Since agriculture is already popular and fish farming is expanding, promotion of IAA systems could provide an entry point for an increased adoption of aquaculture among rural farmers.
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| 15. |
- Nyangoko, Baraka, 1989-
(författare)
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Managing Mangrove Ecosystem Services for Local Livelihoods and Adaptations in Tanzania
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Recognizing the importance of ecosystem services (ES) for peoples' livelihoods and well-being is important for decision-making processes on conservation. Mangrove ecosystems in Tanzania are protected by law, but they continue to be exposed to degradation and loss, and there is still limited information about the awareness, preferences, status and trends of the ES they provide. This thesis aims to explore the link between mangrove ecosystem services (MES) and community livelihoods, changes in MES and associated drivers of change, adaptation options and their management in Tanzania, using the Rufiji Delta and Pangani Estuary as case studies. A mixed framework of methods including focus group discussions, key informant interviews, household surveys, direct observations, and literature reviews was used to gather data. Provisioning services were the most commonly identified MES, and they were more often reported to be deteriorating than regulating, cultural, and supporting services. Proximity to mangrove forest and residence time were positively associated with communities' awareness of all identified MES. Poles for building, firewood for cooking, coastal protection, and fisheries habitats were perceived as the most important MES for sustaining local livelihoods, though perceptions varied between sites. Reliance on mangrove resources was significantly predicted by household residence time, household main occupation, household size, and the cost of alternative resources to substitute mangrove wood as a source of domestic fuel. Illegal harvesting of mangrove poles, rice cultivation, climate change and inadequate governance and conservation measures were identified as the most critical drivers of mangrove degradation, but differed significantly from place to place. Fishing was perceived as the most impacted livelihood occupation compared to the other groups of occupations. Potential ways to adapt to environmental changes in the study areas included reliance on MES for ecosystem-based adaptation (EbA), switching of occupation, diversifying crops, offshore fishing, and migrating to other areas. This thesis argues that the linkage between MES and human well-being is site-specific, and drivers impacting on mangroves and their associated services vary spatially and is greatly accelerated by anthropogenic disturbances. Raising more awareness about the multifunctionality of mangroves and committing to participatory forest management that involves local people, as well as reforming the current forest policy by incorporating clear legal mechanisms for engaging communities around mangrove management and diversifying livelihood options are re-emphasized as appropriate ways to improve mangrove conservation. Furthermore, investment by providing adequate funding for conservation in long run rather than relying on short-term international donor-funded projects are recommended to government institutions as a basis for sustainable management of mangrove forests in Tanzania.
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| 16. |
- Oostdijk, Maartje, 1988-
(författare)
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Fisheries Management under Individual Transferable Quota : Outcomes for Ecology and Equity
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The management of marine resources pose a difficult commons problem as monitoring behavior is difficult and benefit flows from the resources are uncertain. Implementing individual transferable quota (ITQ) is a management regime in which quasi-property rights are assigned for an often mobile and uncertain environmental resource, fish or marine invertebrates. This thesis addresses sustainability impacts of ITQ’s as a fisheries management tool. The findings demonstrate that fisheries management regimes in which fisheries opportunities are allocated as quota and / or are allocated individually experience reduced overfishing compared to controls that do not have these attributes (Paper I), however the analysis found less support for transferability and no support for longer duration being associated to any change in the probability of overfishing. In addition, a longitudinal study showed that with an adaptive design ecological and economic goals could be balanced in an important mixed fishery in Iceland (Paper II), and based on such findings suggested that several policy changes could be implemented to modify the ecological risk of catch-quota balancing allowances. Additional longitudinal analyses allowed to conclude that rapid consolidation in an important small-boat fishing sector in Iceland, which may have had negative implications for local fishing communities (Paper III), and that on average since the introduction of ITQ’s total amount of quota traded stayed below around 60% for the main commercial species in the Icelandic ITQ system. Moreover, the results of Paper IV also show that in case of a credible announcement of quota revocation in the future there would be scope for policy reform. Finally, research is beginning to emerge that shows that marine species are unequally affected by climate change. In a final chapter the analyses show that under different scenarios of global change a re-shaping of the Icelandic foodweb is likely (Paper V). The re-shaping of the foodweb will be to the benefit of some resource users and to the loss of others. In general, the findings from all the analyses together demonstrate that there could be benefits to individual quota implementation for fisheries sustainability and that some of the hypothesized trade-offs could potentially be balanced, the thesis highlights ways forward in investigating the common pool problems in fisheries management.
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| 17. |
- Page, Jessica Faye, 1991-
(författare)
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Sustainable Urban and Regional Development and Related Ecosystem Services and Water-Climate Interactions
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To accommodate a growing global population while mitigating climate change, urban areas must grow while minimising environmental impacts. To achieve this, a city must be treated as a complex socio-ecological system in which many actors and subsystems act in unclear and unpredictable ways. This thesis explores the workings and interactions of this complex socio-ecological system by assessing how urban and regional planning and policy decisions affect the contributions of cities to climate change, and whether appropriate planning and policy tools can minimise these contributions. Computer models were developed to investigate and couple planning and policy decisions and their potential impacts on the environment, particularly in terms of greenhouse gas (GHG) emissions to the atmosphere. The models were then employed for generation of scientific knowledge and for converting this knowledge into practical planning tools and recommendations.Methods used in developing models that reflect complex urban systems included cooperation with experienced county planners to improve model accuracy; coupling of sub-system models in a socio-ecological framework for scenario analysis of the outcomes of planning and policy decisions in terms of GHG emissions; systems breakdown analysis of green-blue contributions to the urban carbon cycle; and modelling to identify how these contributions could be harnessed to reduce net urban emissions. The main study area was Stockholm County, Sweden, with later extension of the modelling approach to 54 major European cities. Cooperation with Stockholm County planners during model development resulted in an improved tool for scientific research that was also suited to practical planning, increasing the potential for knowledge developed through scientific research to be applied in reality. Scenario analysis of policies for Stockholm County revealed that zoning reduced the extra GHG emissions associated with necessary urban growth by 72% compared with a baseline scenario. Analysis of the urban carbon cycle in Stockholm County showed that vegetative carbon sequestration helped offset GHG emissions locally, but that re-emissions via surface waters compromised the potential to reach ‘net-zero’ emissions from Stockholm County. However, climate action goals for Stockholm could still be achieved if its ambitious emissions reduction plans are realised and if the current sequestration capacity of Stockholm County’s many green areas can be maintained in coming decades. Extensive modelling of urban emissions in multiple European cities showed potential for green-space sequestration and revealed that nature-based solutions (NbS) applied at city scale could help reduce urban emissions. Incorporation of NbS into climate action plans for these cities would maximise the associated GHG emissions reduction and increase the likelihood of the cities achieving their climate action goals. In conclusion, the climate change impacts of future urban expansion could be mitigated by incorporating planning and policy tools such as zoning, protection of green-blue spaces and NbS into whole-system urban and regional development plans. This could bring cities closer to achieving truly sustainable urban development.
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| 18. |
- Rocha, Eva, 1985-
(författare)
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Trees and the environment : Possibilities and challenges in tree-ring research across spatial and temporal scales based on case studies in Sweden.
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The need to understand and quantify the magnitude and frequency of past and current environmental changes increased the demand for high-resolution proxy data across spatial and temporal scales. Due to their long lifespan and global distribution, trees provide a unique and continuous record of environmental variability. More specifically, trees can be used as proxies of environmental conditions since their physical and chemical characteristics reflect the conditions in which they have been growing.Focused on case studies from Sweden, this thesis presents a sample of applications where different tree-ring parameters were combined and compared with meteorological records, historical documents and soil profiles to provide information on natural and human-induced changes in the environment. Tree-ring width (TRW) measurements from living trees and subfossil wood from Jämtland, west-central Sweden, were combined to develop a two-millennia-long chronology from Norway spruce, a species that has been traditionally overlooked in dendroclimatic assessments in the region. This record enabled delivery of new perspectives on past regional climate variability and represents an important achievement for inter-and intraregional proxy analyses.A unique maximum latewood density (MXD) chronology was developed from trees growing in drought-prone environments in the Stockholm Archipelago and used to reconstruct past precipitation variability for east-central Sweden. The results showed that MXD provides a stronger climate–growth relationship than TRW and allows a broader target seasonal average (May - July) to be reconstructed.The resolution provided by ring width and density measurements is insufficient to understand growth responses to environmental stress at intra-annual scales. A pilot study using stem radial increment data retrieved from several dendrometers placed in the Stockholm area provided important insights into daily and seasonal growth dynamics in response to site-specific conditions. The main results show that short-term events, such as droughts, can significantly impact trees’ climate–growth relationship and their vegetative period.Annually resolved time-series of wood elemental composition were used to investigate environmental contamination at a glassworks site in southern Sweden. The dendrochemical signals showed large variability both between and within the species in analysis, suggesting a strong control of the soil properties and species-specific uptake on trees’ elemental composition.The findings presented in this thesis show that tree rings can be a highly suitable proxy to understand past and ongoing environmental changes and the link between ecosystems, climate and human activities. Overall, regionally developed networks of tree-ring data elucidated processes behind large-scale climate dynamics and provided new insights on past regional climate variability. In addition, locally-focused studies revealed fine-grained variations and the challenges of understanding the numerous physiological interactions between individual trees and the surrounding environment.
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| 19. |
- Roth, Nina, 1984-
(författare)
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Grasslands in a changing climate : Summer drought and winter warming effects on grassland vegetation
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Grasslands harbour a high biodiversity of both plants and animals, and they provide many ecosystem services such as fodder production, pollination, and carbon storage. Climate change is likely to alter grassland ecosystems, with the effects varying according to the exact nature and timing of changes. Hence, understanding of seasonal climate change effects on grasslands and how negative impacts can be reduced is important to maintain biodiversity and to ensure continued delivery of ecosystem services.In this thesis I explored how seasonally specific aspects of climate change, i.e. summer drought and winter warming, affect aboveground plant biomass, plant community composition, and floral resources for pollinating insects. Moreover, I aimed to outline ways to mitigate potential negative climate change effects by adapting conventional grazing and mowing regimes and/or by applying soil amendments (i.e. compost) as a novel management method. Soil amendments have been suggested as a method to increase carbon sequestration and they might mitigate negative drought effects. However, there is no empirical evidence of how European grassland ecosystems would be affected should such measures be applied.A literature review of climate change studies revealed that the terms ‘wetter’ and ‘drier’ can be defined by a variety of hydroclimatic variables, or are not defined at all, making it difficult to synthesise climate change effects on ecosystems and societies. In two in-situ experiments I investigated the effects of summer drought (using rain-out shelters), soil amendments and mowing on four Swedish grasslands, and the effects of winter warming (using open-top chambers) and sheep grazing on three British Upland grasslands. The experimental summer drought caused a non-significant decline in aboveground plant biomass (i.e. fodder production), plant species diversity, and floral resources. Applying soil amendments increased aboveground plant biomass and floral resources (in yearly mown plots), but these positive effects were reduced under drought. There were signs of negative soil amendment effects on legumes. Winter warming led to an increase in graminoid biomass and a decrease in bryophyte biomass. Sheep grazing buffered the growth of a competitive species under winter warming but had only minor effects overall.My thesis emphasizes that it is important to clearly define terms like ‘wetter’ and ‘drier’ when studying effects of climate change on ecosystems, since clarifying the effects of climate across habitats and management interventions will require the synthesis of results across a range of experimental and observational systems. My field experiments indicate that even relatively small climatic changes affect grassland plant biomass and biodiversity, and that these effects depend on the season and grassland site in question. Furthermore, soil amendments have mainly positive effects on the grassland vegetation, indicating that they have potential for broad-scale application as a method to increase carbon sequestration. Given that my experiments were set up in-situ in grasslands and the treatments were rather mild and realistic in magnitude according to local climate change predictions, the observed vegetation changes within only three years are quite remarkable. They therefore highlight the need for detailed empirical and mechanistic understanding of how climate change processes are likely to affect grassland ecosystems.
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| 20. |
- Senkondo, William, 1982-
(författare)
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Modelling water resources despite data limitations in Tanzania’s Kilombero Valley
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Water is a vital resource for survival on the Earth. Sustainable management of water resources is therefore required for the wellbeing of present and future generations. A cornerstone of water resources management is scientific guidance supported by relevant data (in terms of quantity and quality). Most developing regions, where such guidance is crucial due to the intimate connection between natural resources and livelihoods, unfortunately face data limitations. This thesis aims to develop systematic approaches for informing water resources management in data limited regions. Specifically, this work targets Tanzania’s Kilombero Valley (KV) basin as an exemplar of a data limited region undergoing social-economic development through expansion and intensification of agriculture and other water-related interventions. Through a synthesis of lessons learned from the ongoing evolution of hydrological modelling development for water resources management in the Eastern Africa, several promising approaches were identified that could potentially be robust despite data limitations across the region. Putting these approaches into practice, recession analysis based on non-continuous discharge data in conjunction with estimations of the actual evapotranspiration (ET) using remote sensing techniques provided a basis to improve process understanding and help characterize the hydrological systems in the KV basin. This understanding translated into more-informed parameter estimation and improved accuracy when integrated into the development of a hydrological modelling framework using the Soil and Water Assessment Tool (SWAT) model. The modeling framework established for KV has potential to be used as tool for estimating impacts of water resources management strategies relative to future anthropogenic pressures and climatic changes. What is even more promising, is the possibility to derive scientific guidance to assist water resources management in a data limited region through implementation of an integrated workflow which employs state-of-the-science approaches. The methodological framework for model development adopted in this thesis could be applied in any data limited region facing similar challenges as those of the KV basin.
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| 21. |
- Vigouroux, Guillaume, 1991-
(författare)
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Managing coastal eutrophication : Land-sea and hydroclimatic linkages with focus on the Baltic coastal system
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Eutrophication endangers coastal ecosystems all over the world and is most often associated with an increase in anthropogenic nutrient loads to coastal waters, which fuel the growth of algae and create a variety of environmental problems. This is also the case for the Baltic Sea where coastal waters may be affected by various land, coast-sea, and hydroclimatic drivers and feedbacks, over different scales, including the eutrophic open sea. This thesis aims at improving our understanding of how these drivers affect coastal eutrophication and its management opportunities across the various coupled scales of the Baltic land-coast-sea system. To achieve this aim, the interactions between land-catchment, coastal, and open sea processes, and their influences on coastal eutrophication have been investigated through water quality modelling with applications to specific Baltic coastal waters. Hydroclimatic influences on the propagation of change-impacts through the land-coast-sea continuum to coastal eutrophication have also been investigated via the water quality modelling and additional analysis of actual water quality trends over the last 30 years along the Swedish coast. Moreover, coastal eutrophication research on the Baltic Sea system has been investigated through scientific literature analysis with focus on how the reported research has accounted for and linked components in the land-coast-sea system, and the aim to identify possible research gaps.Results show that impacts of water quality improvements in the open sea propagate to a large share of the coastal waters, especially for phosphorus and phytoplankton, while impacts of reducing nutrient loads from land are more localised and more pronounced for nitrogen than for phosphorus. Therefore, reducing coastal nitrogen, phosphorus and phytoplankton concentrations requires both regional measures for open sea improvements and local land-catchment measures for reduction of nutrient loads to the specific coast. Moreover, data analysis shows that trends in coastal Summer chlorophyll a (Chl-a) are well correlated with those in open sea Summer Chl-a and in riverine nitrogen loads. Regarding hydroclimatic drivers, warmer and wetter conditions are found to complicate remediation of coastal eutrophication in comparison to drier and colder conditions. In addition, trends in coastal Summer Chl-a are well correlated with those in sea-ice conditions. These results highlight the various land-based, coastal, open sea, and hydroclimatic drivers and conditions that mix, interact in and influence the coastal waters. The various driver, management, and ecosystem components involved are overall included in Baltic coastal eutrophication research. However, specific coastal management measures, and feedbacks between drivers and impacts of coastal eutrophication are under-investigated, and the social and ecological components of the whole land-coast-sea system are not well-connected in the research.Furthermore, long-lived legacy sources on land, as well as at sea, have not been much accounted for in coastal eutrophication research so far. This calls for further research on recovery time scales and specific remediation measures that can be effective against such sources, like mussel farming and wetlands. Finally, coastal eutrophication management needs to account for the influences on local coastal conditions from a melting pot of multi-scale drivers and biogeochemical as well as ecological impacts and feedbacks.
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| 22. |
- Watts, Hannah, 1994-
(författare)
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Exploring beneath the surface of glacial landscapes : Implementing and improving geophysical investigations in glaciated environments
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The warming climate is having profound impacts on glacier dynamics and extents. To improve our predictions of future ice mass changes, we require an enhanced understanding of both past and present glacial processes. The physical properties and structure of glacial sediments and landforms aid reconstructions of past environments and ice dynamics on numerous scales. Traditionally, these factors have been studied using glacial geological techniques such as sedimentary logging. While this provides valuable in situ data, there are numerous limitations, namely the limited availability and spatial extent of exposures. In recent decades, near-surface geophysical techniques have gained in popularity within the fields of glaciology, geomorphology, and sedimentology. Geophysics offers a non-invasive means of obtaining spatially extensive data on substrate properties and architecture, however issues such as signal scattering and interpretation ambiguity in complex glaciated environments restrict its application.This thesis exemplifies how near-surface geophysical techniques can aid glacial landscape interpretations focusing on ground-penetrating radar, seismic refraction, and multi-channel analysis of surface waves. It explores the current limitations of the methods and outlines solutions to improve their applicability, in terms of geophysical campaign success, as well as uncertainty estimation and visualisation. The reliability of geophysical interpretations can be improved by including direct substrate observations in campaigns. Here, the benefits of performing detailed sediment logging alongside geophysical surveys are exemplified, together with descriptions and explanations of associated method adaptations.Through a combination of method updates and applied studies, this thesis highlights the great potential for geophysical techniques in improving our understanding of glacial processes and outlines potential avenues for further work in this area.
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| 23. |
- Åhlén, Imenne, 1991-
(författare)
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Ecosystem services of wetlands and wetlandscapes under hydro-climatic change : Impacts of water flow and inundation patterns
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Wetlands provide ecosystem services valuable for human society and are therefore often considered as nature based solution to different environmental problems. However, with centuries of wetland degradation due to anthropogenic pressures, such as agricultural expansion and forest industry, as well as pressures from climate change, there are large challenges for sustainable wetland management. Thus, for wetland protection and restoration practices to be successful, a deepened understanding on the actual mechanisms controlling wetland functions is required. Understanding how wetlands are connected, with and influenced, by their surrounding environment is also needed. Although most pressures experienced by wetlands operate on scales beyond the individual wetland scale, relatively few studies have thus far addressed large-scale functions and ecosystem service provision from hydrologically interconnected wetlands at the scale of wetlandscapes (i.e., the wetlands’ aggregated hydrological catchments in the landscape). The aim of this thesis is to investigate ecosystem service delivery from wetlands and wetlandscapes under hydro-climatic changes, considering 25 different wetlandscapes located in four different climate zones of the world. The thesis also systematically quantifies ecohydrological characteristics important for ecosystem service delivery and biodiversity support of wetlands and wetlandscapes in the Norrström Drainage basin located near Stockholm, Sweden. Conducted hydro-climatic analyses showed that impacts of climate change on wetlandscapes cannot be fully understood from average changes in climatic variables of the climate zones within which the wetlandscapes are located. This may be due to the fact that wetlands are not randomly and evenly distributed within climate zones, but may be located in areas subject to stronger climatic changes than regional means. In addition, anthropogenic pressures were on average shown to have higher impacts on runoff in wetlandscapes in comparison to climate change. The pressures however showed relatively large variability between different wetlandscapes, which needs to be considered in mitigation strategies against wetland degradation and deterioration. Similarly, regarding wetlandscape ecohydrological characteristics, results indicated that there are variability between wetlandscapes of different sizes, where larger wetlandscapes showed features that can support ecosystem services to larger degree than small wetlandscapes. Large spatial variability in wetland ecohydrological characteristics was also seen within a wetlandscape. For instance, water storage dynamics and buffering capacity varied depending on the position of the wetland in the landscape. These differences in hydrological conditions were shown to result in different inundation dynamics between wetlands, which for instance also showed to impact insect community composition.Overall, this thesis shows that assessments of wetland ecosystem services need to be addressed using a wetlandscape approach, combined with actual on site hydrological measurements. The approach used in this thesis could help decrease uncertainties related to the impacts of hydro-climatic changes and anthropogenic pressures on wetlands and wetlandscapes, supporting location-specific wetland management strategies related to creation, restoration and sustainable use of wetlands and their ecosystems.
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| 24. |
- Österlin, Carl, 1984-
(författare)
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Nature conservation, landscape change and indigenous rights : The role of Sámi reindeer herding for environmental objectives in the Swedish mountain landscape
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The 14th Swedish national environmental objective, ‘a Magnificent Mountain Landscape’, requires a mountain landscape characterized by reindeer grazing. The Swedish mountains landscape, part of the Scandes, has been shaped by traditional indigenous Sámi reindeer herding and its grazed environments are dependent on reindeer. In spite of this, the mountain region is often referred to as the last wilderness in Europe. Twenty years since its adoption the aims of this environmental objective for the Swedish mountains is still not achieved. Sweden is internationally often seen as a frontrunner for environmental ambitions, but formal indigenous rights remain relatively weak. In the case of the Magnificent Mountain Landscape objective, the environmental ambitions are dependent on the continuation of a traditional indigenous livelihood and land use based on reindeer herding. While the mountain objective explicitly focus on the mountain area the attainment of the objective is dependent on developments in the whole reindeer grazing area that encompasses vast areas outside the Scandes. Reindeer herding is, however, under increasing pressure from multiple anthropogenic pressures like climate change and encroachments from various types of natural resource extraction on traditional grazing grounds. Land use planning that ensure the continuation of a viable reindeer herding in the whole reindeer herding landscape, not only the mountain areas proper, is therefore essential if the Magnificent Mountains Landscape objective is to be achieved. The thesis is guided by three main research questions: 1/ how have multiple pressures developed in the reindeer herding area in northern Sweden, 2/ how has Sámi participation in land use planning unfolded in northern Sweden, and 3/ what possibilities/conditions are there in place to maintain/sustain the environmental state in the Swedish mountain region given current multiple pressures and planning processes? Based on a transdisciplinary systems approach as well as on quantitative and qualitative methods the results show that stressing weather events have increased in the reindeer herding area, alongside with rapid and significant increase in industrial land use for natural resource extraction. The actual process of rapidly increasing, as well as cumulative, industrial land use also reduce the ability for Sámi reindeer herding communities to influece land use planning. Meanwhile the cumulative effects assesssments for proposed industrial projects poorly describe cumulative effects on reindeer herding. Protected areas in the mountain region that should be requesting the ecosystem services of reindeer grazing also unsufficiently do so because of a too dominant view of its nature as a wilderness, with the implication that reindeer herding is less valued in nature conservation management. If the ambitious environmental objectives for the Swedish mountain range are to be reached it also means that the continuation of traditional Sámi reindeer herding needs to be safeguarded in the whole reindeer herding area, also outside the mountains.
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