Browsing by Subject "Environmental Change"

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  • Korhonen, Henni (Helsingin yliopisto, 2021)
    The focus of this thesis is on environmental agency in two different video games, The Sims 4 Eco Lifestyle and Final Fantasy VII Remake. The research questions aim to answer how the player can act as an environmental agent in these two games and what are the key differences between these games. The study is executed in a form of qualitative two-case case study with the help of close reading. With close reading eight different types of agencies that form the typology of this study, will be analysed in order to answer the research questions. The data for this thesis was collected by playing both games and taking notes by following close reading. The notes were then analysed with the different types of agencies. The results showed clear overlapping of the types of agencies, and it could be said that environmental agency can be used better in the game when the overlapping is happening. The agencies complemented each other and made the possible learning process in the game more fulfilling. The main difference between the game seems to be that The Sims 4 Eco Lifestyle as a life simulation game offers more diverse possibilities for environmental player agency. The studies about environmental games are mainly focused on serious games and not so much on commercial games. Video games hold great potential to engage people in environmental things especially with the help of player agency. It offers the player the ability to make meaningful choices and if they are structure well, the player can see the consequences of their agency which serves as an effective feedback which could lead to positive learning. In this case, the environmental agency in the game could be transformed into real-life environmental agency. As video games have become more immersive and their environments more realistic, it could be worth considering that separating virtual environment from the real-life one might not be necessary anymore. Therefore, games like The Sims 4 Eco Lifestyle and Final Fantasy VII Remake could serve as an example of how environmental agency within them could be harnessed into wider use.
  • Hanstén, Magnus (Helsingin yliopisto, 2019)
    An increasing number of fisheries utilize rights-based management approaches for achieving economic, social and environmental sustainability. It is widely accepted that fisheries management is to a large extent about managing human behaviour, hence social acceptance is prerequisite for a successful management regime. Based on stakeholder interviews, this study analyses the opinions related to the recently implemented individual transferable quota (ITQ) system for the Finnish herring and sprat fisheries. Similarly, opinions were collected in 2007 by Kulmala et al. related to a possible implementation of ITQs, thus creating a unique opportunity to compile results from both a pre and post individual quota management implementation scenario. In 2007, it was suggested that fishers would largely support an ITQ system in Finland. Accordingly, this study implies that most of the Finnish stakeholders are content with the properties of the new system, however inequalities were perceived among fishers targeting fish for human consumption. In general, the system is expected to achieve its primary goal of improved economic efficiency within the fishery industry.
  • Azam, Gausul (Helsingin yliopisto, 2020)
    Dog activities (urination and defecation) can be a source of nitrogen accumulation in the snowpack of urban parks. Urban parks are commonly visited by urban residents and excessive buildup of nitrogen in snowpack can be a health concern. This accumulation of nitrogen in snowpack may wash away during spring with the runoff of melting snow, which can cause the eutrophication and deterioration of lake ecosystems. In this study, I investigated the concentration of some nitrogen-related compounds along with a few physical parameters in the snowpack of urban parks and compared these between areas with high dog activities and areas with no dog activities. I hypothesized that, nitrogen concentrations will be higher in areas with high dog activities, like snowpack beside paths than in areas with no dog activities. The study was performed in 10 parks of two cities in Finland; Helsinki and Lahti. In these parks, samples were collected from snowpack immediately next to walking paths (path edge), and in control areas 8 m away from these paths, where dogs were unlikely to visit. Samples were collected from February to April of 2019. The concentration nitrogen from snow samples of both parts of parks were compared. The study showed that, the concentration of most nitrogen species, e.g. Total Nitrogen (TN), ammonium (NH4+), Total Organic Nitrogen (TON), and electrical conductivity followed a similar pattern of having higher values in snow from path edges where dog activities were the highest. However, the concentration of NO3 – and pH values were both slightly lower in the path edge samples compared to control areas undisturbed by dogs, but differences were not statistically significant. Information from this study can be useful for understanding the connection between dog activities and nitrogen build up in snowpack of urban parks, and can also be helpful for designing urban parks by considering environmental and health effects of nitrogen accumulation in the snow from dog activities. My findings can also be useful to urban waterbody related studies, e.g. eutrophication, and the accumulation of nutrients in lakes.
  • Kivilompolo, Sanna-Kaisa (Helsingin yliopisto, 2021)
    Aims of this study. Previous studies have shown cyanobacterial dominance and harmful cyanobacterial blooms to increase due to recent climate warming. The increase of aggressively blooming species and toxin-producing strains of cyanobacteria has been predicted to further increase in the future. However, information on the response of cyanobacteria communities to environmental forcing in the Arctic region – which is experiencing warming at over twice the rate compared to the global average – has been insufficient. Thus, it is crucial to study how algal and cyanobacterial communities have developed after industrialization to better understand and predict future trends of subarctic algal communities as well as changes within cyanobacteria communities experiencing environmental forcing. This study aims to provide information on the effect of recent climate warming and lake browning on algal communities in subarctic lakes, with a special focus on cyanobacteria and cyanotoxins. Materials and methods. Modern and historical primary producer group abundances of 23 subarctic lakes located on an ideal temperature and vegetation gradient were studied using sedimentary algal pigments as a proxy. The top-bottom method was used to study both changes within algal communities during the last ca. 150 years and the broader trends in algal communities of subarctic lakes. Pigment data was analyzed together with environmental data using ordination analyses (principal component analysis (PCA) and redundancy analysis (RDA)) as well as other statistical analyses in order to determine possible trends of change and to reveal the environmental variables that have the strongest impact on cyanobacterial abundance. Results and conclusions. Algal communities have changed during the last ca. 150 years and show a general trend of increased primary production as well as lake browning in the spruce, pine and birch (SPB) vegetation zone. Siliceous algae generally dominate modern algal communities, and relative abundances of cyanobacteria have declined throughout the vegetation gradient. Within the Barren (Ba)- and mountain birch woodland (MBW) vegetation zones, cyanobacteria communities show a marked decline in the abundance of assumed benthic species based on pigment data, and low abundances of planktic picocyanobacteria. However, due to climate warming and lake browning, abundances of cyanobacteria have increased in several sites within the SPB vegetation zone and are suspected to indicate an increase of harmful planktic species. The most significant environmental variables controlling the abundance of cyanobacteria were total phosphorus, temperature and the amount of organic matter. The results highlight the urgent need to mitigate climate warming in order to preserve the unique biota and characteristics of Arctic and subarctic lake ecosystems, and to prevent the possible harmful increase of cyanotoxins in these sensitive ecosystems.
  • Raubenheimer, Marie-Claire (Helsingin yliopisto, 2020)
    Oil spillages represent a serious environmental hazard for flora and fauna of marine and coastal ecosystems. Though marine oil spills have decreased since the 1970s, the increasing production of petroleum goods remains a potential source of pollution due to its use and transportation. When aquatic organisms, including fish, are exposed to toxic oil compounds, this can cause sublethal morphological changes and increase mortality. In this context, herring have been frequently studied, and results suggest that particularly herrings eggs and larvae are highly susceptible to oil toxicity. In this thesis, a Bayesian meta-analysis was conducted to investigate the effects of crude and fuel oil on the mortality of herring eggs from the genus Clupea. Observations from laboratory studies, collected during a literature review, served as input for the statistical analysis. To this end, Bayesian inference modeling was applied to generate posterior probability distributions for additional mortality caused by exposure to oil mixtures. Also, oil concentration, oil type, exposure time, and temperature were analyzed to study possible correlations with mortality impacts. The results of this study suggest that acute mortality of exposed herring eggs is similar to mortality observed for individuals exposed to only small concentrations or none at all. Of all evaluated oil types, medium grade crude oil caused the most significant change in instantaneous mortality with increasing oil concentration. Generally, distinct oil types had a greater influence on mortality outcomes than temperatures at the given concentrations. For the lowest temperatures, some correlations for increased mortality were found. Overall, the unexplained variability between the reviewed studies has a relatively small influence on mortality outcomes. In conclusion, the mortality of exposed herrings eggs is most likely delayed due to sublethal effects, rather than immediate, at the modeled concentrations. Altogether, uncertainty amongst the posterior probability distributions is high, indicating a wide possibility range for the monitored parameters' actual values. The reasons for elevated uncertainty likely stem from diverse experimental setups, biological differences between tested species, relatively small sample sizes, and model-related issues. Thus, future research could consider additional variables, information from observational studies and other fish species to reduce uncertainty in mortality outcomes.
  • Lahtela, Eero (Helsingin yliopisto, 2021)
    Municipal environmental authorities are required to conduct environmental monitoring. Unmanned aerial vehicles, UAVs, may be helpful in environmental monitoring but their applicability as a tool for municipal environmental monitoring has not been studied. In this thesis it was studied, how municipalities have been utilizing UAVs. Additionally, UAVs applicability for environmental monitoring and inspection work was tested using a litter monitoring experiment as an example. In the first part of the study, a questionnaire was sent to municipal environmental authorities in Finland, to municipalities in Sweden and to those participating in Eurocities WG Waste group (n = 512), covering the used applications, their utilization frequencies and successfulness, reasons for failures and future plans. The results were analyzed using descriptive statistics. In the second part of the study, a UAV was utilized in a litter monitoring experiment on four sites in Helsinki. Litter by category and leaves were counted based on visual observations from UAV imagery. The accuracy of UAV imagery detection was assessed by comparing its and ground assessment (GA) results. On one site, a control group also carried out UAV imagery detections in order to assess the magnitude of bias or offset occurring when both the GA and the litter detection from UAV imagery are conducted by a single individual. The Wilcoxon signed rank and Cronbach’s α reliability tests were used for statistical analysis of the results. Response rate of the questionnaire was low, 3.7% (n = 19). The pool of used applications was extensive and covered a variety of monitoring and inspecting targets with emphasis on the presumably manually piloted applications. Utilization was very successful. The most important reasons for failures were poor weather followed by lack of information and expertise. UAVs were included in the future plans of most participants for municipal environmental monitoring purposes. The UAV imagery detection accuracies of litter and leaves compared to the GA results were high, 90.5% for litter and 87.5% for litter and leaves, and no statistically significant differences existed between the assessment results. Especially leaves proved challenging to detect from UAV imagery. The control group’s detection accuracies were 67.9% without and 49.0% with leaves, and with leaves the results differed with statistical significance (p = 0.028). The internal reliability of the control group was relatively high, α = 0.776 without and α = 0.805 with leaves. UAVs are deemed sufficiently accurate and versatile as monitoring and inspecting tools for municipal environmental authorities. They have the capability to complement ground assessments or, with certain prerequisites, even function as an independent monitoring method. Further application and detection method development and research on municipal UAV utilization are needed.
  • Repetti, Sonja I. (Helsingin yliopisto, 2022)
    My master’s thesis aims to determine the effect of salinity on phytoplankton traits related to nutrient acquisition, and particularly how this interacts with resource availability. Salinity is an important driver structuring phytoplankton communities in the Baltic Sea. Salinity can also influence nutrient uptake by increasing metabolic rates required for osmotic adjustment. Thus, interaction between salinity and nutrient availability is expected to change community structure by altering phytoplankton traits determining resource competition. This is a particularly relevant area of study for the Baltic Sea due to predicted future freshening of the sea’s upper layer. We performed a microcosm experiment using artificial communities of 10 diverse phytoplankton species grown under different combinations of salinity (0, 5, 12 and 24), Nitrogen to Phosphorus molar ratio (N:P ratio = 2, 10, 16 and 80) and light (10 and 130 µmol photon m-2 s-1) conditions. A three-way interaction among these environmental parameters influenced phytoplankton traits associated with resource competition, as well as the presence and proportions of phytoplankton taxa. Light limitation inhibited community growth under all salinity conditions, but allowed diatom Phaeodactylum tricornutum to dominate. Community growth rate was higher under high light, but also more variable between salinity conditions. The strongest negative effects of nutrient limitation (N, P, and both nutrients together), both on growth rate and taxonomic diversity, were observed in the highest salinity treatment. In the freshwater treatment with the highest proportion of green algae Monoraphidium sp., N-limitation did not inhibit phytoplankton community growth and P-limitation had a more profound negative effect on community performance. Decreasing salinity appeared to decrease community C:N and C:P ratios. This shift is in opposition to the increasing C:N and C:P predicted as a consequence of other climate change-related drivers. Our results emphasise the importance of a trade-off between salinity and resource limitation in functioning of phytoplankton communities and suggest that future freshening of the Baltic Sea is likely to modify phytoplankton community composition and performance.
  • Vikkula, Sami (Helsingin yliopisto, 2021)
    Oil spills in aquatic environments are devastating disasters with both biological and economic impacts. Fish populations are among the many subjects of these impacts. In literature, there are numerous assessments of oil spill impacts on fish populations. From all applied research methods, the focus of this thesis is on Bayesian methods. In prior research, several Bayesian models have been developed for assessing oil spill impacts on fish populations. These models, however, have focused on the assessment of impacts from past spills. They have not been used for predicting impacts of possible future oil spills. Furthermore, the models have not utilized data from laboratory studies. Some examples can be found of models assessing economic impacts of oil spills on fish populations however, none of them assess the economic impacts that follow from decreases in biomass. The aim of this thesis is to develop a Bayesian bioeconomic prediction model, which would be able to predict oil spill impacts on Baltic Sea main basin herring population, and the consequential economic impacts on fishermen. The idea is to predict the impacts of several hypothetical oil spill scenarios. As a result of this thesis, a bioeconomic prediction model was developed, which can predict both biological and economic impacts of oil spills on Baltic Sea main basin herring through additional oil induced mortality of herring eggs. The model can be applied to other fish populations in other regions as well. The model utilizes laboratory studies for assessing population level impacts. The model can be used for both assessing risks of the impacts of possible future oil spills, and for decision analysis after a spill has already occurred. Furthermore, the model can be used for assessing unknown aspects of past oil spills. The economic predictions can be used, for example, to estimate the compensations that could possibly be paid to fishermen. In the future, the prediction model should be developed further, especially regarding its stock-recruitment relationship assumptions. In addition, the model’s assumptions regarding the calculation of oil induced additional mortality and the economic impacts, should be expanded.
  • Courroux, Maxime (Helsingin yliopisto, 2021)
    The changes in lake diatom assemblages as a response to climate warming over the past three decades were examined in 26 lakes across Northwestern Finnish Lapland using multivariate statistical techniques. The lakes are distributed along a steep climatic and vegetational gradient, covering three distinct vegetation zones spanning boreal coniferous forest, mountain birch woodland, and treeless tundra. Lakes were selected following a study realised by Weckström and Korhola in 2001, who had sampled the same lakes for surface-sediment diatom assemblages, physical, and chemical limnological variables. Climate data from the past 30 years was retrieved, showing a slow and steady yearly increase in temperature, with strong seasonal fluctuation and fall months experiencing the strongest warming. Surface sediment samples were taken from the lakes and their diatom communities analysed. A total of 185 diatom taxa representing 27 genera were recorded. Ordination techniques (DCA, CCA) at the genus and species level were performed to identify the main patterns of variation between diatom data from the original data set and the current study, and their relationship to environmental variables. Strong changes were recorded in four of the lakes with major shifts in dominant diatom species. Moderate changes were recorded in eight lakes, where dominance changes were recorded for a few species while the majority remained unchanged. The remaining 14 lakes did not show noticeable changes over the 30-year period. Changes observed in the studied lakes did not follow a widely observed pattern in northern Hemisphere lakes. The results indicate that while climate change is a driving factor behind changing lake dynamics with increasing temperatures and decreasing lake ice cover duration, it cannot be the only force responsible.
  • Lahtinen, Oskari (Helsingin yliopisto, 2022)
    Agriculture is emitting ~6.2 Gt CO2-Eq. annually, which accounts for ~12 % of the total annual net anthropogenic greenhouse gas (GHG) emissions globally. Agriculture emits N2O and CH4, and it is responsible globally for ~79% of N2O emissions and ~40% CH4 emissions. These emissions are vital since N2O and CH4 are 273- and 27-times greater GHG than CO2, respectively. There are many different food production systems developed to reduce these emissions. One of the most promising systems is agroforestry. Agroforestry is a complex system where trees and/or shrubs are interacting with crops and/or animals. Agroforestry is an old practice which can provide plenty of advantages, e.g., increased yields, increased biodiversity, and increased carbon sequestration. Therefore, the interest towards it has been increasing in the last decades. In this master’s thesis the different maize production systems in Zambia were studied. The comparison was conducted between low-input maize monoculture where only external input was maize seed for sowing; high-input maize monoculture where mineral fertilizers and seeds for sowing were used; and maize-Faidherbia albida agroforestry system where only external input was maize seed for sowing. The goal of this master’s thesis was to find out, which production system is having the lowest climate change potential in the Central Province of Zambia. To conduct this study, Life Cycle Assessment (LCA) -method was used. Two cases were used in LCA, i.e., Case 1 with functional unit (FU) of 1000 kg d.m. maize grain, and Case 2 with FU of 3 ha maize field. Also, four sensitivity analyses were conducted. The result from this study indicates that agroforestry system had the lowest climate change potential in both cases, and in most of the sensitivity analyses. Only exception was found in the sensitivity analysis where above-ground biomass of F. albida was substituting hydropower. In this sensitivity analysis the monoculture without external inputs had the lowest climate change potential. Since the food production in Zambia must increase in the future to reduce the hunger, the high-input system or agroforestry system are more favourable options as they produce higher crop yields. When taking the climate change potential into account, according to the results of this thesis, the agroforestry system provides more benefits. The results of this thesis can provide new knowledge which could be used in the future decision-making processes. Yet, in the future studies, more complex agroforestry systems with more sustainability pillars should be considered to provide improved information for decision-making.
  • Pykäri, Janina (Helsingin yliopisto, 2022)
    Light is crucial for aquatic ecosystems, as photosynthesis supports the higher trophic levels. Light attenuates in water due to absorption and scattering by optically active substances (OAS), the main ones in coastal environments being chlorophyll-a (chl-a), particulate matter and coloured dissolved organic matter (CDOM). Light attenuation measurements are also important indicators of many environmental changes. Traditionally, Secchi depth has been used to monitor changes in light attenuation. However, Secchi depth (ZS) is a not an accurate estimate of light attenuation, and conversion to light attenuation coefficient (Kd) is needed to study light conditions as aquatic organisms observe them. Therefore, calibration between methods is important. In this study, light attenuation was estimated with Secchi disc, a light meter and light loggers to scrutinize the possibilities of autonomous measurements in this context. The aims of the study were 1) to compare three methods for estimating light attenuation and 2) to identify the environmental drivers affecting the relationships and accuracy of these methods, and 3) to assess the possibility of using conductivity as a proxy for light attenuation. The main hypotheses were that the differences in conversion between ZS and the two sensor-based methods in different concentrations of optically active substances can be explained by contribution of scattering to light attenuation, and that variation in different Kd-estimates is due to the different measurement spectra. The effect of three OASs (chl-a, particulate matter, CDOM) on differences among light attenuation estimates were quantified in Pohjanpitäjänlahti bay. Light attenuation was mainly controlled by CDOM, followed by particulate matter and chl-a. Conductivity was found to be a good proxy for light attenuation. However, there was a mixed signal if the differences among methods could be explained by OAS concentrations or conductivity, as the hypotheses were supported with one device pair but not with the other. Therefore, the differences among light measurement methods might stem from the characteristics of the devices or measurement errors. However, all the methods were found suitable for tracking changes in light attenuation and a summary table of the advantages and disadvantages of each method is presented to help choose a suitable method to estimate light attenuation e.g., in future studies or environmental monitoring.
  • Skogberg, Mikko (Helsingin yliopisto, 2020)
    Static floating chamber (FC) measurements of CH₄ and CO₂ fluxes from northern boreal river Kitinen were analyzed for this thesis. Measurements were carried out in summer 2018. Spatiotemporal variability was measured in the fluxes by comparing three chamber measuring locations: the opposite river banks and the middle of the river. Mean CO₂ flux estimate was 0.83±0.54 μmol CO₂ m⁻² s⁻¹ (mean ± SD, n = 73), consistent with other estimates for similar systems, with a corresponding k₆₀₀ CO₂ gas transfer velocity estimate of 17±9 cm h⁻¹ . Nonlinear modelling of CO₂ flux was found useful for analyzing floating chamber data from a river. The mean CH₄ flux was 0.0084±0.0047 μmol CH₄ m⁻² s⁻¹ , slightly lower than the median for different river systems in literature. The flux estimates were compared with eddy covariance measurements (EC). FC measurements are expected to give larger results, but additionally chambers are known to overestimate fluxes in flowing water. The comparison yielded chamber fluxes 3.3 and 2.9 times the EC median values for CO₂ and CH₄ respectively. Fluxes were similar between the three locations, and they peaked in late July for both gases in all loca- tions. Some differences over the river cross-section were observed. Discharge was significantly correlated to fluxes in the middle of the river, which could be explained by inhomogeneous flow. On two measuring days in early August, the mid-river CO₂ fluxes were three times those observed near the banks. The difference was also measured in methane. No clear cause was determined, but measuring spatial variation in surface water gas concentrations and flow could clarify the causes of similar observations in further studies.
  • Karvonen, Lassi (Helsingin yliopisto, 2021)
    As water flow encounters an object on the sea floor, its hydrodynamics change. Accelerated currents and vortices develop around the object with changing intensity as a function of distance from its proximity. This leads to erosion and aggradation of sediment, known as scour. Studies focusing on formation processes of scour often involve locating visible scour sites by sonar scanning the geomorphology of the seafloor. However, the effects of scour on macroinfauna and small-scale sediment characteristics are not visible in sonar images. In this Master’s thesis, scour at a shipwreck of a timber-built historic sailing ship, the Joskär shipwreck, was first identified by scanning the study area with side-scan sonar, and by measuring water depth contours around the shipwreck by scuba diving. Sediment samples were then taken inside the area assumed to be under the most pressure from scour. Samples from three separate distances on two transects drawn outwards from the hull of the shipwreck were collected and analysed for sediment grain size, organic content, and species assemblages of macroinfauna. In addition, macrofauna were analysed for individual lengths, number of individuals, diversity index, and functional groups. All samples were collected with a core tube sampler operated by a scuba diver. The methods used in this Master’s thesis widen the concept of scour past the sole physical processes observable with sonar to a more holistic level that considers the quality of biological, geological, and chemical characteristics of the benthic environment. The results of the present Master’s thesis show that the quality of the sediment near Joskär shipwreck varies within a relatively small scale. Organic content of the sediment was the most potent descriptor of scour at the study site, exhibiting a consistent decreasing trend as distance to the shipwreck increased on both sampled transects. Sediment grain size became finer as distance to the shipwreck increased. However, compared to grain size, based on visual observations of the sediment samples, shell debris content of the sediment could possibly act as a better measure of presence of scour. The variability of characteristics of macroinfaunal communities as a function of distance from Joskär shipwreck was not a viable tool to describe the presence of scour, as no consistent trends of the variables were observed. As no control site was included in the study design, the characteristics of the benthic environment inside the scour around Joskär shipwreck could not be compared to the seafloor unaffected by scour. Further research could reveal possible variation between these distinct habitats, and that way produce valuable indicators of scour. The hypothesis in the present thesis was that macroinfaunal assemblages and sediment characteristics would exhibit variation between the sampling sites as a function of distance from the shipwreck. The observed trends of sediment characteristics validated a part of the hypothesis, showcasing the utility of sediment characteristics in describing scour at Joskär shipwreck. However, a part of the hypothesis was rejected, as no consistent trends of macroinfaunal features were present.
  • Vikfors, Sofia (Helsingin yliopisto, 2020)
    Microplastics (MPs) are widespread environmental pollutants that have been detected in virtually all environmental compartments. Despite this, research has mainly focused on the impacts of microplastic on shorelines and at sea. The effects of MPs on terrestrial ecosystems has been sparsely investigated, and there are only a few studies on direct effects on terrestrial plants. Although plastic polymers are considered inert and non-hazardous, toxic additives are often added to the polymers during manufacture which may leach out into the environment, displaying ecotoxic effects. In this work, the effects of microplastic particles and microplastic leachate on the germination and growth of Lolium multiflorum (Italian ryegrass) was investigated. High density polyethylene (HDPE), which is one of the plastic polymers with the largest annual production, was chosen as the plastic material for investigation. New MPs, artificially aged MPs, MPs from the Lahti region, and MPs from Port Elizabet, South Africa was used in parallel to compare the effects of ageing and regional environmental factors on the ecotoxicity of MPs. The total germination percentage, mean germination rate, synchronization index, germination index, and time to 50% germination was investigated, as well as the root lengths, shoot lengths, root/shoot ratio, and fresh weights of the seedlings. The results showed that exposure to new and Lahti MPs and leachates severely inhibited the extent and speed of the germination of L. multiflorum, whereas all categories of MPs and leachates inhibited the growth to some extent. Most severe inhibition in germination and growth was seen for the new MP and new leachate, followed by Lahti MP and Lahti leachate. The root growth, shoot growth, and plant biomass were also severely reduced for these exposure media. For the aged and Port Elizabeth material, there were slight but significant (p < 0.05) inhibition in root lengths and fresh weights, but no significant inhibition in the germination parameters. These findings indicate that ageing severely reduces the ecotoxic effects of MPs, and that regional environmental factors affect the ecotoxicity of MPs. Microplastics from Port Elizabeth were significantly less toxic to L. multiflorum than MPs from the Lahti region, possibly due to the warmer climate in South Africa. Another explanation could be that the plastic material collected in Port Elizabeth wast older than the one from Lahti. There was little to no difference in germination and growth between seeds exposed to MPs or leachates of the same origin, indicating that it is the substances leaching out of the MPs that are responsible for their ecotoxicity.
  • Turunen, Pauliina (Helsingin yliopisto, 2021)
    Peatlands play an important role in the carbon cycle. Natural peatlands are in general sinks of carbon dioxide (CO2) and sources of methane (CH4), whereas drained peatland forests are CH4 sinks but their CO2 emissions increase compared to natural peatlands. Rotational even-aged forestry followed by ditch network maintenance (DNM) affect the water dynamics of the soil by increasing the water table level (WTL) first during clear-cut after which the WTL is lowered by DNM. Rising of WTL causes more anaerobic conditions and risk that CH4 sink turns into CH4 emissions. Lowering the WTL causes more aerobic conditions and strengthens the CH4 sink function but also increases CO2 emissions. In continuous cover forestry (CCF) where only part of the trees are removed, WTL would be naturally maintained. This could maintain CH4 sinks while lowering CO2 emissions by keeping the WTL at an adequate depth. Net emissions of CO2 and CH4 could be expected to follow the changes in CO2 and CH4 concentrations in soil. To understand the processes isotopic values can be used to interpret the production pathways of CO2 and CH4 since different pathways produce different isotope values. In this master’s thesis the aim was to study how the concentration of CO2 and CH4 as well as CO2 isotope values change in a peat soil and how partial harvest affects them. Gas samples were collected from the peat profile (5 – 65cm) at two different drained peatland forests, Lettosuo and Paroninkorpi, from control plots and partial harvested plots during 2019 and 2020. Samples were also collected from the moss layer. In addition, WTL, temperature of peat and O2 concentrations were measured. Concentrations and isotope values were analysed the laboratory with gas chromatography and isotope analyser (Picarro G2201-i). Water table level and temperature were generally higher in partial harvested areas than in control. Highest concentrations of both CO2 and CH4 were found in the deeper layers of the soil. Partial harvest had higher CO2 and CH4 concentrations in the deep layers (50 – 65cm) than control. The differences between partial harvest and control areas could be explained with the higher WTL in partial harvest. The measured isotopic values of CO2 indicated that most of the CO2 in the soil was derived from atmosphere or heterotrophic respiration and only <<20 % of CO2 was derived from CH4 oxidation. Even though both in control and in partial harvest the CH4 concentrations in the deep soil layers were high, the oxidation processes decrease the concentrations under the atmospheric CH4 concentration maintaining the CH4 sinks in both treatments. In partial harvest the CH4 sink is not in risk due to oxidation even though the WTL is higher. This should be verified with gas flux measurements.
  • Karimaa, Anna-Elina (Helsingin yliopisto, 2021)
    Pollinator abundance and diversity are declining at an alarming rate around the world, which poses a threat to ecosystem stability and human wellbeing. There are signs that growing pollination deficits are limiting agricultural yields in Finland and globally. More information is urgently needed on how changes in pollinator communities affect crop yields and how adequate pollination services could be achieved across a range of crops and locations. This study explores the effects of pollinator abundance and diversity on caraway (Carum carvi L.) pollination and yield. Caraway is partly wind-pollinated, but insect pollination has been shown to increase its yield. Flower visits of pollinating insects were monitored on 30 caraway fields in southern Finland in summer 2019. Yield samples were collected from open-pollinated plants and from control plants excluded from pollinators. Pollinator exclusion reduced caraway fruit set by 13.2% and seed yield by 39.6%. Fruit set, 100-seed weight and seed yield increased with increasing flower visitation. Pollinator species richness and Shannon index had no significant effect on the yield components, but evenness of the pollinator community had a negative effect on seed yield and the numbers of umbels and umbellets in the caraway plants. The most abundant pollinators visiting caraway were syrphid flies, non-syrphid Diptera and honeybees. Visits by syrphid flies and honeybees increased seed yield, while visits by non-syrphid Diptera, solitary bees and Lepidoptera had no significant effect on the yield components. Flower visits by beetles reduced 100-seed weight. The results show that syrphid flies provide an important pollinator service for caraway cultivation. It would be beneficial to study which syrphid fly species are the most effective pollinators for caraway and how to manage fields and farmland landscapes to increase their numbers. Relying only on managed honeybees to enhance caraway pollination may not be advisable due to their potential negative effects on wild pollinators. While increased pollinator diversity did not improve caraway pollination or yield in this one-season study, it may be important for the stability of pollinator services in long term.
  • Berglund, Nora (Helsingin yliopisto, 2022)
    In Finland and in many other European countries, indoor housing of dairy cattle has been increasing at the expense of grazing. According to Finnish legislation, only dairy cows housed in tie-stalls are obligated to graze for 60 days per year between May and September. Pressure to intensify production leads to increase in herd sizes, regional concentration, lack of suitable pastureland near large barns, and automation of milking. Conversely, grazing is regarded as important for animal welfare, maintenance of biodiversity and cultural landscapes. Farmer perceptions towards grazing have not been studied in Finland comprehensively, which need to be understood better in order to provide adequate support for sustainable management of grazing. The research aims at gaining understanding of the external and internal factors driv- ing the farm-level decision making related to grazing regimes. Concept of good farming ideal is used to examine farmers’ decision-making. The data was collected from 26 cattle farms with a gradient of grazing from zero to maximum. Firstly, an online questionnaire was sent out to farmers and secondly, semi-structured inter- views were conducted with 7 dairy producers, to further explore farmer views about grazing, biodiversity, and animal welfare. The results show farmers who practice grazing to perceive it more positively than the farmers who do not graze. Some of the farmers who grazed seemed to consider it almost as an intrinsic value, whereas farmers with no grazing saw it as an inef- ficient production method, which they were afraid would become an obligation. The most im- portant internal factors driving decision-making about grazing based on the questionnaire and interviews, were animal welfare, decreased workload because of grazing, infrastructure of the farm, economic aspects, and benefits of grazing to biodiversity and landscape values. Exter- nal factors found to affect the decision of grazing were incentives, regulations, and consumer expectations. Animal welfare was found to be a basis for production for many and the most important feature valued for good farming, to which grazing was seen to contribute. The re- sults imply subsidies regarding grazing should be higher for grazing to be considered profita- ble and more enjoyable by farmers.
  • Ahonen, Veronica (Helsingin yliopisto, 2019)
    Permafrost peatlands have the capacity to store significant amounts of carbon, and thus they act as important controllers of the climate. Approximately 14% of the world’s soil organic carbon pool is stored in permafrost peatlands, which are sensitive to climatic fluctuations due to their location in the high latitudes of the subarctic zone. Permafrost peatlands also act as a habitat for a large number of moisture-sensitive organisms, such as bryophytes and testate amoebae, which can be used to study how the hydrology of peatlands has changed and will continue to change throughout time, giving us an opportunity to predict the future of peatlands under a changing climate. In this Master’s Thesis I examined the testate amoebae composition and used these species as indicators to study hydrological fluctuations from three subarctic permafrost peatland cores extracted from Taavavuoma and Abisko in northern Sweden. The species compositions were combined with radiocarbon (14C) and lead (210Pb) dates to reconstruct the past water table levels for the late Holocene, spanning four climatic periods. The reconstructions were then compared to past studies on testate amoebae to understand how permafrost peatlands and their species assemblages respond to changes in the hydrology of the active layer of the peat. Out of the study sites only the Taavavuoma cores spanned the Dark Age Cold Period (DACP) and Medieval Climate Anomaly (MCA). Species compositions in both cores indicated fluctuating water tables during the DACP, but during the MCA the results began to contradict with one site showing a wetter, and the other a drier MCA. Two out of three study sites indicated a wetter Little Ice Age and a drier Post-Industrial Warming, supporting past studies indicating similar results, whereas one study site gave opposite results. The results indicated large variability in testate amoebae assemblages throughout time, indicating that the hydrology of peatlands can change very abruptly and vary considerably even on a local scale. Modelling is however complicated by the poorly known ecology of testate amoebae, which is why a multi-proxy approach is essential to reliably predict the future fate of permafrost peatlands.
  • Boxström, Agneta (Helsingin yliopisto, 2021)
    Abstract: Northern boreal peatlands form one of the biggest carbon pools in the biosphere, thus having great potential to cause major changes to the global carbon cycle. The ongoing recent warming may affect the carbon dynamics though factors, such as, vegetation, hydrology and permafrost balance. As the future is still uncertain there are no definitive answers on how the peatlands will react in the future. Fortunately, moisture sensitive organisms such as, bryophytes and testate amoeba is preserved in the peat and can therefore be used to reconstruct past climatic shifts. In this thesis I studied palaeohydrology and peat accumulation over the last two millennia, from three peat cores originating in a permafrost peatland in Rogovaya, Russia. I used testate amoeba as a proxy of past moisture conditions and plotted the taxa composition of each core against 14C and 210Pb dated samples, to reconstruct past moisture shifts. The results were also supplemented by plant macrofossil and carbon accumulation data for more robust results. Of the three cores, Rog11 provided the oldest testate amoeba dataset by reaching the Dark Ages Cold Period. During this period there were indications of dry moisture conditions followed by a wet Medieval Warm Period. The Little Ice Age gave indications of a drying trend, while toward the end of the LIA Rog8 indicated opposite moisture conditions. From the end of the LIA onwards a general trend of drying and increased carbon accumulated is noted. Yet, during the last decade the trend has turned. The wet shift might indicate that the threshold for the peatland has been reached and the amount of melting permafrost has exceeded the evapotranspiration rate. As a conclusion my result indicates that the dynamics of both hydrology and carbon are complicated processes affected by both autogenic and allogenic factors, therefore causing large variability even on a local scale. The absence of widely spread observations of the most recent wet shift also indicates that the response of the peatland to the recent warming might be unequal. To rectify this situation, continued research is crucial, so that we can increase our understanding of climate-peatland interactions.
  • Keränen, Fanny (Helsingin yliopisto, 2021)
    This study aimed to identify conservation landscapes with potential to be mutually beneficial for people and African savanna elephants (Loxodonta africana) in South Africa through spatial conservation planning analyses that integrate ecological and socioeconomic data. The research questions were: (i) what are the most ecologically suitable areas for the reintroduction of elephants, and (ii) which of these areas provide the best opportunities for also sustaining socioeconomic development of local people. The first question was answered with an ecological model that predicts habitat suitability for elephants, developed by a combination of literature review, expert opinion, and GIS-based methods. The second question was answered by combining the ecological model with socioeconomic criteria in Zonation spatial conservation planning software. The results show that the central part of South Africa holds most potential for elephant conservation as it has the largest uniform area of high-quality habitat, while the area also meets the socioeconomic criteria. The priority areas for the conservation of elephants were classified into top priority classes of 1%, 2%, 5%, 10% and 20%. The identified areas hold an unrealized opportunity in the wildlife and ecotourism sectors, and the reintroduction of elephants to those areas could provide the foundation for long-term economic activity of local communities e.g. in the form of elephant-based ecotourism, while contributing to the conservation of elephants. Conserving just the top 5% priority areas would grow South African protected area estate by approximately three million hectares and increase the current elephant range by approximately 75%. Ideally, the results of this study could be used to inform the on-going decision-making process on where to allocate resources for elephant conservation in South Africa.