Browsing by study line "Ympäristömuutos"
Now showing items 101-120 of 143
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Siirtonurmen ja metsäkuntan vaikutus päiväkoti- ikäisten lasten ihon mikrobiomin monimuotoisuuteen (2022)Immune-mediated diseases, such as various allergies and asthma, are increasing rapidly in an urbanized world where biodiversity is steadily declining. Decreased biodiversity and homogenous microbiota have been associated with weaker immune defence. Studies show that contact with the natural environment enriches the human microbiota, promotes immune response, and protects against allergies and inflammatory diseases. For this reason, in order to prevent immune-mediated diseases, solutions have been sought from nature-based approaches in which the immune system encounters environmental microbial stimuli in a natural way. The aim of this master's thesis was to study how different nature-based materials (sod and forest floor) affect the skin microbiota of kindergarten-age children and to examine how different factors such as varying weather conditions and different sampling times affect the results. The results supported the hygiene hypothesis and previous research according to which increasing biodiversity can have a positive effect on human skin microbial communities. A positive effect on children's skin was achieved with sod alone, which is important information in the development of suitable biodiverse materials for urban planning. The results also supported the surmise that different weather conditions and sampling methods can significantly affect the results.
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Soil nitrogen content and isotope ratios in urban remnant forests: What have dogs got to do with it? (2024)Keeping dogs (Canis familiaris) affects the environment. One significant effect of dogs in the environment is the production and deposition of urine. Unlike other waste, dog urine cannot be easily collected by owners, leading to unfiltered introduction into the soil. Dog urine is high in urea, which hydrolyzes to ammonium and nitrate. These soil nitrogen forms have the potential to change other soil properties that may cause harm in plant or microbial health, and contributing to eutrophication. In this thesis I investigate the impacts of dogs on soil nitrogen properties and their connection with human population density and closeness to walking paths in urban remnant forests. To evaluate the level of impact of dogs and to gain knowledge on the current nitrogen content and δ15N in urban remnant forests, five urban remnant forests were examined. Within each forest, soil nitrogen forms, δ15N in the soil and foliage samples, as well as total carbon and nitrogen content of the soil were compared, besides basic soil properties between dog-affected and control areas. The study revealed elevated levels of soil electrical conductivity, ammonium, and nitrate, as well as soil and foliage δ15N in dog-affected areas. Unexpectedly, soil acidity was lower in samples taken next to paths where dogs can potentially urinate. Organic matter content and total nitrogen and carbon content of the soils were higher where dogs are not frequent visitors, meanwhile the carbon-to-nitrogen ratio was also higher. These findings show that the impacts of dog urine on the soil should be considered in urban planning and further research is needed to understand the significance of it.
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(2021)Underwater light climate in mountain lakes is controlled by dissolved organic carbon concentrations and by lake ice regimes. Both are affected by local, regional and global variables linked to anthropogenic disturbances such as climate change and atmospheric pollution. Aim of this work was to investigate changes in underwater light climate over the past ~200 years in two oligotrophic mountain lakes and how it reflects on diatom (Bacillariophyceae) guild distribution. For these aims, diatom communities and ecological guilds were analyzed from sediment core and contemporary habitat samples along a depth gradient. In addition, sediment inferred chlorophyll a (CHLa) and lake water total organic carbon (TOC) were analyzed to detect development of primary production and lake water carbon content. Results showed that acidification of the lakes together with climate induced changes have been important drivers of the ecology of the lakes. Lake water TOC showed a decline and subsequent increase in line with the acidification and subsequent recovery of the lakes, likely affecting underwater light climate in the lakes. However, this did not reflect unambiguously into changes in diatom functionality. Warming has likely contributed to diversification of the diatom community over the study period while no distinct increases were observed in whole lake primary production. Overall, if the present study could not distinguish the exact role of underwater light in driving changes in diatom communities and functional traits, the result show that human pressures have left distinct imprints in the development of biotic communities in these remote mountain lakes.
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(2024)As an almost enclosed sea, the Baltic Sea is generally defined as eutrophic, as external nutrient loading has exceeded the natural processing capacity of the system during the last 50-100 years. Nutrients have also accumulated in the sediments of the Baltic Sea. The Baltic Sea is naturally sensitive to eutrophication due to the combination of very long residence times and stratification increasing deep sea anoxia. Research questions for this systematic review are: how much have the nutrient concentrations and the trophic state of the Baltic Sea changed from the Litorina stage to the end of the pre-industrial era compared with the industrial era – year 2000, how has the nutrient status of the Baltic Sea changed between the year 2000 and the 2020´s and how do the future (modelled) scenarios of eutrophication of the Baltic Sea compare to the present state? This systematic review followed the PRISMA process. To be included in this thesis, each article found in the search had to fulfil at least one inclusion criterion without any exclusion criteria. The aim of the criteria was to find all time-unlimited original studies and necessary review articles. The databases of my thesis are Helka, Helda, Scopus, Web of Science and Google Scholar. Moreover, I included in my thesis some relevant reports from HELCOM, Finnish Environment Institute, Natural Resources Institute Finland, and Ministry of the Environment. Overall, 89 articles qualified answering at least one research question. 66 articles answered one research question. 19 articles answered two research questions 1-2 and 2-3, but none discussed the combination 1 and 3. Four articles answered all research questions. Over the millennia, hypoxia and cyanobacteria blooms took place in many parts of the Baltic Sea. As the Litorina Sea stabilized, there was more oxygen in the deep basins whilst phosphate decreased in the surface waters. At the beginning of the industrial era, nitrogen and phosphorus loads started to rise significantly. When it comes to the future scenarios of the eutrophication of the Baltic Sea, the trophic state might generally 1) decrease, 2) improve somewhat, or 3) improve to a good status in most basins. A near-pristine Baltic Sea is not reached in any of the scenarios.
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(2024)Kiertotaloutta on esitetty ratkaisuksi rakennussektorin kestävyyshaasteisiin, sillä kiertotalouden perusstrategiat tehostavat rakennus- ja purkujätteen sisältämien materiaalien hyötykäyttöä, vähentävät syntyvän jätteen määrää ja kasvattavat resurssitehokkuutta. Suomi on sitoutunut hyödyntämään kaikesta rakennus- ja purkujätteestä materiaalina vähintään 70 %, mutta tavoitteen saavuttaminen vaatii lisätoimia. Kaupungeilla on merkittävä rooli kiertotalouden mukaisen materiaalikierron edistämisessä. Tämä tutkielma liittyy Lahden kaupungin organisoimaan Niemi Living Lab -pilottihankkeeseen, jossa suunnitellaan Lahdessa sijaitsevan Niemen alueen muutosta teollisuusalueesta asuin- ja virkistysalueeksi. Hankkeen perusajatuksena on miettiä, miten alueen purkumateriaalit saataisiin hyödynnettyä mahdollisimman tehokkaasti kiertotalouden periaatteita noudattaen. Tutkimuksen tavoitteena oli tehdä yleistason kartoitus alueelta ensimmäisenä purettavien tehdasrakennusten purkumateriaaleista ja niiden uudelleenkäyttö- ja kierrätysmahdollisuuksista sekä selvittää, millaisia haasteita purkumateriaalien uudelleenkäytölle ja kierrätykselle on alan yritysten näkökulmasta. Tutkimus on tyypiltään tapaustutkimus, jonka aineisto koostui kenttäpäivien havainnoista, materiaalilaskelmista ja asiantuntijahaastatteluista. Tiedonkeruussa hyödynnettiin lisäksi rakennus- ja purkujätteitä käsittelevien yritysten internetsivuja ja ajankohtaisia dokumentteja. Haastateltavia yrityksiä olivat Purkupiha Oy, Gles-yhtiöt, Umacon Oy, Salpamaa Oy, Tarpaper Recycling Finland Oy, Kuusakoski Oy, EcoUp Oyj ja Remeo. Aineiston analyysissa käytettiin sisällönanalyysin menetelmiä. Tulosten perusteella tehdasrakennuksista syntyy noin 101 499 tonnia purkumateriaalia. Kartoitettuihin materiaalijakeisiin kuuluivat betoni, tiili, metalli, mineraalivilla, puu, kattohuopa eli bitumikate, lasi, muovi ja kumi, kipsi, keramiikka, asfaltti ja sähkö- ja elekroniikkalaiteromu (SER). Uudelleenkäyttöpotentiaalia on esimerkiksi ilmanvaihtolaitteilla, kuljettimilla, pumpuilla, teräksisillä rakennusosilla, liimapuutuotteilla ja tiilillä. Kaikille materiaalijakeille voidaan lähtökohtaisesti osoittaa jokin kierrätysväylä, mutta jakeisiin sisältyy joitakin materiaalityyppejä tai -laatuja, joita ei kyetä kierrättämään. Useita arvoa lisääviä kierrätysmenetelmiä on jo olemassa, mutta purkumateriaaleja hyödynnetään yhä paljon energiatuotannossa tai alhaisen arvon menetelmillä. Uudelleenkäytön ja kierrätyksen haasteissa korostuivat erityisesti taloudelliset näkökulmat sekä lainsäädännön vaikutus liiketoimintaan ja markkinoiden kehitykseen.
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Testing a novel methodology to assess carbon degradation in different coastal soft-sediment habitats (2023)Coastal habitats contribute significantly to global carbon cycling. These ecosystems store carbon into the sediment and provide a crucial ecosystem service of sequestering carbon from atmosphere. In situ carbon degradation assessment methods in coastal sediments have not been widely developed. A novel, cost-effective method for assessing degradation rates, ROMA (rapid organic matter assessment), has been developed recently, but it has not been tested yet in cool, shallow subtidal coastal areas. In this Master’s thesis, the aim is to test the ROMA methodology in shallow coastal habitats in Northern Baltic Sea. To investigate the method, following research questions were studied: (1) can carbon degradation be assessed by using the ROMA- method in the shallow coastal habitats, (2) whether carbon degradation rates differ between two sites with varying sediment characteristics, (3) how various diversity metrics and environmental context can be linked to carbon degradation rates. Results of this study show that ROMA method is feasible to assess carbon degradation rates in shallow coastal areas. There was a difference in the degradation rates between the study sites with different environmental characteristics, but the driver for the carbon degradation still seemed somewhat unclear. The methodology should be developed and trialled further, as it is promising cost-effective way to measure carbon degradation in situ.
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(2022)Mercury (Hg) is a heavy metal acknowledged as a worldwide contaminant that accumulates in organisms and biomagnifies in food webs. The organic methylmercury (MeHg) species is harmful to animals, including humans, and mainly derived from the diet. The dietary Hg consumed by fish is mostly removed through the intestine, but some of the MeHg bioaccumulates, especially in the white muscle tissue of fish. Perch (Perca fluviatilis) and roach (Rutilus rutilus) are commonly found fish species in Finland. Perch has additional im-portance as it is the national fish of Finland, a popular food fish, as well as a monitoring species used to evaluate the chemical status of lakes. Seasonal variation of Hg in muscle tissue of fish is supposedly caused by starvation in winter, which condenses Hg in the muscle, and growth dilution in summer, which refers to fast somatic growth during the growing season, which dilutes Hg in the muscle. Similar to winter, spawning has also been found to condense Hg in muscle tissue of fish due to high energy investment into gonad development. Seasonal variation of Hg and variables driving seasonal changes have been shown to differ between fish species. Seasonal variation has been studied mainly during the open-water season. However, less is known about how winter conditions under ice affect Hg levels in fish. In this MSc thesis, I asked (Q1) How total mercury (THg) content in the muscle tissue of perch and roach change annually? (Q2) How THg bioaccumulation in the muscle tissue of perch and roach change annually? (Q3) What are the factors explaining annual variation in THg content in the muscle tissue of perch and roach? The practical application of results was to discuss if annual variation should be considered in monitoring programs and human health questions. The materials used in this study were collected from Lake Pääjärvi monthly from March 2020 to March 2021. Fish were collected using gillnet series. Length, weight, sex, sexual maturity, stomach fullness, Fulton’s condition factor (K), and muscle THg were determined from each fish. The annual length-corrected THg content variation was tested using analysis of variance. The annual THg bioaccumulation variation in the relationship between muscle and fish length was tested using simple linear regression analysis, and the seasonal variation in THg bioaccumulation was tested with LOESS regression analysis. Variables affecting seasonal variation were tested with stepwise multiple linear regression analysis. THg content of perch was the highest in winter and spring and the lowest in fall, while roach showed no significant seasonal variation. THg bioaccumulation of both species was highest in winter, spring, and early summer and lowest in fall. Perch displayed more substantial seasonal variation than roach. Biological and environmental variables that explained the THg content of perch were length, ice thickness, gonadosomatic index (GSI), light, and condition factor. Variables that explained the THg content of roach were length, sex, and total phosphorus (Tot-P). This study confirmed that starvation in winter, growth dilution in summer, and spawning in spring/early summer are vital factors driving seasonal variation. Due to evident seasonal variation, monitoring month should be pre-set in current monitoring programs.
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(2024)Climate change has caused a vital need to identify the coastal ecosystems with high carbon sequestration capacity, i.e. Blue Carbon ecosystems. The ability of these ecosystems to sequester carbon is strongly influenced by the physical environment. However, previous research on Blue Carbon potential of coastal macrophyte ecosystems has mainly focused on single seagrass species whereas research on multispecies meadows along environmental gradients, such as wave exposure has been scarce. Nonetheless, exposure and depth are known to shape the functional structure of macrophyte communities. The aim of this study was to investigate if exposure and depth affect the functional structure and biomass-bound carbon stocks of macrophyte communities along an exposure gradient in an archipelago area in the western Gulf of Finland, northern Baltic Sea. Macrophyte samples were collected at two different depths (1-2 m and 3-4 m) from 20 soft-bottom sites with different exposure levels. At each site, the functional community structure was quantified by measuring four functional traits (maximum height, root depth, root-to-shoot ratio, specific leaf area), associated with the variation in plant life history strategies and in addition, the plant biomass-bound carbon was determined. The results showed that when moving from the outer to the inner archipelago, the species composition shifted from marine to limnic species, and the community functional structure was shaped by environmental conditions (i.e. wave exposure, light availability, salinity) and depended on the depth. The plant carbon stocks did not differ significantly along the exposure gradient in the shallow areas, while at increasing depth, exposed sites had the highest plant carbon stocks, which can be likely explained with the environmental factors such as light availability. To conclude, these results highlight the need for further research that investigates the connection between environmental drivers, functional traits, and plant carbon stocks to assess the Blue Carbon potential of multispecies macrophyte communities in heterogenous environments.
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(2020)Cladocerans play a key role in the aquatic ecosystem. They are abundant in lakes and are an essential part in the carbon and energy transfer of the food webs. These species are, however, prone to various environmental changes. Estimates have shown that dissolved organic carbon (DOC) concentrations in northern lakes are likely to increase in the future. This increase of DOC in lakes has multiple impacts ranging from nutrient levels to shading impacts reducing primary productions. Investigating changes in cladocerans along a DOC gradient could help us understand how these species might develop in the future in our changing climate. In this Master’s Thesis, I studied how the cladoceran body length and community structure varied between 9 lakes with dissolved organic carbon (DOC) concentration ranging from 2.4-33.5 mg l-1. For the analyses, these lakes where divided into two groups with a threshold of 12 mg l-1 or into groups of three based on their DOC concentrations. Then, the results were compared with cladoceran length data from an earlier study. Additionally, the changes in phytoplankton abundances and communities as well as the relation between DOC concentration and other environmental variables were analysed. The results showed an increase in the cladoceran body length above the DOC threshold. Moreover, the changes in body length varied between the studied genera. Both Ceriodaphnia sp. and Diaphanosoma sp. body length decreased in groups with higher DOC concentrations while Bosmina sp. were larger at high DOC concentrations. DOC concentration did not have any significant effect on the community structure of zooplankton. The studied lakes varied from their environmental condition making comparisons and general statements challenging. The results indicated that DOC concentration regulates the planktonic communities, but it is solely an imprecise predictor for changes in zooplankton communities. However, cladoceran densities seemed to benefit from increased DOC concentrations as nutrient levels also increased. Changes in cladoceran body lengths were challenging to interpret, because there are multiple factors that can have an impact both alone and combined with others.
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(2022)More than half of the global population lives in urban areas. Urban sprawl and densification have affected urban ecosystems and the services they provide. Urban vegetation is one of the most important providers of ecosystem services. Previous studies have shown that plant functional type and age of parks/trees affect soil properties in urban environments. However, knowledge on the effects of plant roots on ecosystem services is limited. In this thesis I focused on exploring the contribution of root biomass to soil carbon and nitrogen accumulation under evergreen and deciduous trees in urban greenspaces. In addition, I explored how soil properties differ based on tree type and age of the park/tree, and how sampling distance from the tree affects root biomass and soil properties. Soil samples were taken at five distances: 1) under the canopy (midway between the trunk and the canopy edge), 2) at the canopy edge, and 3)–5) 1 m apart, starting from the canopy edge. This transect of five distances was replicated three times per tree (30 trees in total). Trees belonging to two functional types were sampled, evergreen (mostly Norway spruce, Picea abies (L.) H. Karst.) and deciduous (Linden, Tilia x europaea L.) trees. Sampling was done in young (ca. 15 years) and old (>70 years) urban parks in Lahti and Helsinki. The results show higher root biomass under young trees than old trees, and spruces had higher root biomass compared to lindens. Root biomass was positively correlated with soil organic matter, soil carbon and soil nitrogen. Sampling distance from the tree affected both root biomass and soil properties in young and old parks. Plant functional type affected soil organic matter, soil carbon, C/N ratio and acidity, but not soil nitrogen. Irrespective of tree type, soil properties varied less in old parks than in young parks between the sampling distances. Soils under old spruces had higher total carbon content compared to young spruces, whereas for lindens, tree age affected soil carbon less on. Total nitrogen content was higher in old parks than in young parks for both tree types. My study provides new information about how park tree roots affect urban park soil carbon and nitrogen accumulation. There are no previous studies on how far this root effect extends, and my study fills this knowledge gap. My results show that tree roots are an important factor in urban park carbon stocks. I also showed that age of the park/tree has an evident effect on urban soil properties. In the light of my research findings, it seems that a significant portion of ecosystem services provided by urban vegetation is produced underground.
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(2021)Microbial diversity can be found everywhere around us. The diversity is however declining globally and the diversity loss is most visible in highly urbanized areas. The lack of microbial biodiversity has been linked to increased risk of certain im-mune mediated diseases most prevalent within urban population. Understanding how diversity differs between urban and rural areas can help us to figure out mechanisms behind biodiversity loss and higher frequency of immune-mediated dis-eases and develop prevention methods for the latter. The aim of the thesis is to study how bacterial communities differ between urban and rural areas using indicator species as proxy. The aim is also to find out if the results support the biodiversity hypothesis. The results of the thesis found out significant differences in diversity indexes between bacterial communities in urban and rural areas, which supports the biodiversity hypothesis. The study also found differences in Proteobacteria diversity index-es, which have been linked to some immune mediated diseases in previous studies.
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(2020)Iron-manganese (FeMn) concretions are found on soft sediment bottoms both in the deep sea and coastal sea areas, formed as a result of a combination of biogeochemical and microbial processes. It has been estimated that concretions occur at least in 11 % of the Finnish marine areas. Concretions form hard substrates on predominantly soft seafloors, and they are therefore suggested to increase geodiversity and habitat complexity of the seafloor. This has been found to correlate with biodiversity of the benthic fauna. Despite their widespread occurrence in the northern Baltic Sea, the ecological importance of FeMn concretions has been left unaddressed. In the recent assessment of threatened habitat types in Finland, concretion fields were classified as a data deficient habitat type. The aim of this study is to examine the role of FeMn concretions as habitats in the Baltic Sea ecosystem. Benthic biodiversity was investigated utilizing two approaches; the abundance of mobile fauna and sessile macrofauna were studied with point-dives. The data was compared to pre-existing data from similar soft bottoms where there are no observations of concretions, collected in the Finnish Inventory Programme for the Underwater Marine Environment (VELMU). Samples for sediment in-fauna were taken with a Van Veen Grab Sampler, and additional data was gathered also from Environmental Information System HERTTA (administered by Environmental Administration). The shape and quantity of concretions appear to affect the abundance of sediment in-fauna. Similarities to the invertebrate composition of soft sediment habitats depends of the soft sediment availability in the habitat, which is dependent on concretion shape and quantity. Crusts seem to affect the faunal composition more than spheroidal and discoidal concretions, as they offer the most complex habitats, significantly different from bare seafloors. Based on this study, the concretion fields should not necessarily be considered as just one habitat type, since the faunal composition appears to differ according to the shape of the concretions.
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(2024)As global temperatures rise due to anthropogenic greenhouse gas emissions, it is becoming increasingly important to mitigate climate change. Agriculture, one of the major contributors to greenhouse gas emissions, has the potential for mitigation by implementing carbon sequestration practices. Biochars, carbon-rich materials derived from biomass pyrolysis, have drawn attention for their potential to sequester carbon and enhance crop growth. However, limited yield effects have been reported in boreal agricultural soils after applying pure biochars to soils. Therefore, application of activated and nutrient enriched biochar has been proposed as an amendment for getting most use of the practice due to slow release of nutrients and carbon sequestration. However, the effects of these new activated biochars on soil biota remain unknown. The study investigates the impact of acid and slurry activated biochar on earthworm community in agricultural soil in southern Finland, focusing on their implications for soil physical properties and ecosystem health. Through a split-plot designed field experiment, with biochar (applied at rate 0 t ha-1 and 20 t ha-1) being the main factor and fertilizer level the sub-plot factor, the interaction between nutrient enriched biochar and earthworm population was examined by assessing earthworms' abundance, biomass, and mean weight. There was no significant effect of the treatments on earthworm abundance, biomass, or mean weight. However, the mean weight showed a notable response to the interaction effect of biochar x fertiliser. Biomass and mean weight were negatively correlated by temperature. Among the other variables, soil water content had positive correlation with temperature. These findings highlight a possible association influenced by soil physicochemical parameters, microbial dynamics, and environmental conditions, even though biochar had no apparent impacts on earthworm density, biomass, or mean weight. In this first-ever field experiment with a high rate of acid and slurry-activated biochar applied to agricultural soil, biochar had no adverse effect on earthworm populations. Thus, the present findings confirm that the application of large amounts of biochar treated with acid and cattle slurry in Nordic agricultural soil is a safe C sequestration method for earthworms at least for a short time period. However, the long-term effect is still a knowledge gap. Addressing this knowledge gap is crucial to apply sustainable agriculture methods that enhance soil properties and health.
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(2020)Northern peatlands have a major role in the global carbon cycle due to their carbon stocks and fluxes of carbon dioxide (CO2) and methane (CH4). Anthropogenic climate change may affect peatland carbon dynamics through changes in e.g. primary production, hydrology, and permafrost dynamics. It is uncertain whether these changes will lead to northern peatlands becoming significant sources of carbon to the atmosphere. Changes in moisture conditions especially can be an important factor in determining the carbon sink potential of northern peatlands. In this thesis I examine the palaeohydrology and peat accumulation over the past centuries in a permafrost peatland complex in Lovozero, Kola Peninsula, Russia. I used testate amoebae as a proxy of past changes in moisture conditions. Other study methods used here are detrended correspondence analysis (DCA) and 14C and 210Pb dating. The results were also supplemented with plant macrofossil and carbon accumulation data provided by other members of the research team. The results show varying responses of the peatland hydrology and peat accumulation to the past climatic shifts, suggesting that the changes have been driven more by autogenic factors rather than climate. However, all three sites indicated a drying trend and an increased peat accumulation for the last century. Yet, the last decade is charachterised by a wet shift. The wet shifts suggest that the peatlands may have crossed a threshold where increased evapotranspiration is exceeded by increased moisture due to thawing permfrost. The surface peat layers of all three sites were dominated by mixotrophic testate amoebae, which may have contributed to the high peat accumulation. The inconsistency of past successional pathways identified at Lovozero peatlands and the drying trend over the past century correspond to the previous studies from northern peatlands elsewhere. However, the most recent surface wetting during the last decade differs from what has been reported for the other northern sites. This suggests that the response mechanisms of peatlands to the anthropogenic climate change may not be uniform. Thus, further research is inevitably needed to increase our understanding of peatland-climate intercations.
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The effect of mowing height on CO2 fluxes and drivers of a clay soil under mixed forage cultivation (2023)Enhancement of soil carbon sink has large potential to mitigate climate change. Earlier studies have suggested that improved management practices could promote climate change mitigation and improve soil fertility. To find out if the carbon sink of a clay soil under improved grassland management in Southern Finland can be enhanced by increasing mowing height at harvest, an experiment was set up with two different mowing heights (6 and 15 cm). Net ecosystem carbon exchange, based on total ecosystem respiration and photosynthetic capacity were monitored with chamber methods during three growing seasons from 2019 to 2021. Also, plant biomass, leaf area index, soil temperature, soil pH, soil water retention capacity, and soil grain size distribution were studied at both mowing height treatments. In this study, negative value is the CO2 flux from the atmosphere to the ecosystem and positive value is the CO2 flux from the ecosystem to the atmosphere. Negative NEE means that the ecosystem gains C when the absolute value of GPP is greater than TER and vice versa. The higher mowing height increased CO2 uptake by plants and caused more negative NEE for the higher mowing height after the grass was harvested. These results indicate that higher mowing height might be better for mitigating climate change. However, mowing height did not have a significant effect on biomass, LAI, TER or soil properties in the experiment. Short lasting and non-existent differences between mowing heights are probably explained by more pronounced compensation growth reaction at the lower mowing height as growth conditions were otherwise similar except for mowing height treatment at both treatments. More frequent measurements, especially after the harvest, could better reveal the dynamics of grass height differences and its effects on GHGs. Better detection of the effect of mowing height on the carbon balance would require even more regular and continuous measurements after harvesting and fertilization in different soil types with experimental setups such as applied in this study.
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(2023)Agroforestry is a collective name for land-use systems and technologies where woody perennials are deliberately used on the same land-management units as agricultural crops and/or animals. Silvopasture is a type of agroforestry that integrates trees, livestock, and forage crops on the same piece of land. This topic is specifically interesting because silvopasture is already present in Finland, mostly in the form of traditional biotopes, despite these being endangered habitats. Agroforestry is also recognized by the Kyoto Protocol as an afforestation practice that has several advantages. These include environmental benefits, increased productivity, and animal welfare. However, there has been discussion on detrimental effects of animal presence to the trees as well. This research aims to explore the effects of silvopasture on trees, cattle, and the environment in South-western Finland traditional biotopes. Several individual criteria are assessed in three categories: woodland, animal performance and biodiversity. Data was collected on three farms on four pastures through field surveys and farmer interviews. The data is analyzed through multi criterium decision analysis (MCDA) with normalized values from agriculture and forestry to assess performance of silvopastures on three separate categories. Results from four pastures follow a somewhat similar pattern but variation occurs. High scores of forest indicators are reached in woodland category whereas biodiversity category results are lower. Silvopasture negatively affects forest regeneration but otherwise does not have adverse effects. Cattle performance is positive outcome whereas biodiversity category has room for improvement. To get more accurate and comprehensive results the research should be conducted during growing season and with several farms around Finland. However, silvopasture is a meaningful measure to diversify habitats, contribute to animal wellbeing and strengthen ecosystem services.
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(2023)Anticipated climate change-related shifts in precipitation patterns in Finland may lead to increased off-season rainfall, potentially causing soil waterlogging. Agricultural soils have significant long-term organic carbon stabilization potential due to organic matter interactions with soil minerals, especially iron (hydr)oxides, which play a key role in stabilizing organic matter. However, iron's sensitivity to redox changes during waterlogging can trigger reduction reactions of iron that lead to iron (hydr)oxide dissolution, releasing the carbon stabilized by iron (hydr)oxides. Given the critical role of soil organic carbon in food production and climate change mitigation, it is imperative to expand our understanding of how altered climate conditions affect particularly soil carbon stabilized by soil minerals, across various soil types and depths. The aim of this work was to investigate interactive effects of climate change induced soil moisture changes and cover crop on concentration and fate of dissolved organic carbon (DOC), dissolved iron and total dissolved carbon (DC; including inorganic and organic C) in two different agricultural mineral soils. In greenhouse experiment, the undisturbed soil monoliths of clay and coarse soil were used to investigate if off-season waterlogging could release organic carbon stabilized by soil minerals. Soil monoliths were saturated with water and pore water samples were collected from three different depths prior, during and after water saturation to monitor changes in the concentrations of iron, DOC and DC. Soil moisture and redox potential (Eh) were also monitored throughout the experiment. The effect of soil type, depth and cover crop on DC as well as differences in concentrations with time were statistically tested using linear mixed effects model and Tukey comparison test. The results of this study showed that waterlogging did not lead to reduction of iron and dissolution of iron (hydr)oxides, and consequently, no organic carbon adsorbed on iron (hydr)oxides was released. The presence of a cover crop did not significantly affect concentration of DOC or iron (hydr)oxide dissolution. However, signs of root exudate mineralization were observed under the cover crop treatment in the topsoil. Clay soil exhibited greater DC concentrations compared to coarse soil. Coarse soil showed signs of downward DOC movement during drainage, while clay soil's mid (30 cm) and bottom (50 cm) layers remained less responsive to soil moisture and Eh changes due to its more compact structure. In the future studies it would be important to focus on improving our understanding of the vulnerability of stabilized organic carbon to changing redox conditions in natural soil systems.
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(2022)Kiihtyvän ilmastonmuutoksen aikana on entistä tärkeämpää löytää tapoja vähentää päästöjä ja sitoa hiiltä. Biohiilen käyttö on yksi keino ilmastonmuutoksen hillitsemiseen, ja sillä on potentiaalia parantaa maatalouden satoja. Ennen kuin biohiilen käyttö voi yleistyä, sen mahdolliset ulkoisvaikutukset, kuten vaikutukset maaperän eliöstöön, on kuitenkin ensin selvitettävä. Tässä opinnäytetyössä tutkittiin biohiilen käytön vaikutuksia mikrobien suhteelliseen runsauteen, kastematoyhteisöihin ja mikrobibiomassaan. Vain lauhkean ja boreaalisen vyöhykkeen kenttätutkimukset olivat osana tutkimusta. Biohiilen vaikutukset mikrobiryhmien suhteelliseen määrään selvitettiin kirjallisuuskatsauksella. Kirjallisuuskatsaus tehtiin myös selvittäessä biohiilen vaikutuksia kastematoihin. Biohiilen vaikutukset mikrobibiomassaan selvitettiin meta-analyysillä. Meta-analyysissä käytetyt tutkimukset luokiteltiin muuttujien, kuten biohiilen raaka-aineen, pyrolyysilämpötilan, maaperän pH:n, SOC:n, maaperän rakenteen ja biohiilen levitysmäärän perusteella. Tätä kautta voitiin selvittää, voisiko jokin näistä muuttujista selittää meta-analyysin tulokset. Mikrobien suhteellisen runsauden havaittiin muuttuvan biohiilen lisäyksen myötä, mutta reagoivat organismiryhmät vaihtelivat suuresti ja vaikutus yleensä haihtui ajan myötä. Biohiilen lisääminen ei vaikuttanut kastematoihin merkittävästi. Meta-analyysien tulokset viittaavat siihen, että biohiilellä ei myöskään ole merkittävää vaikutusta mikrobien kokonaisbiomassaan. Eri muuttujilla tehdyt meta-analyysit viittaavat siihen, että biohiilen lisäyksellä on positiivisin vaikutus mikrobien biomassaan happamissa maaperissä, joissa on karkea rakenne ja korkea SOC-pitoisuus, kun biohiiltä tuotetaan 500 °C–700 °C:ssa ja levitetään määrinä, jotka ovat suurempia tai yhtä suuri kuin 30 t ha-1. Biohiilen raaka-aineella ei havaittu olevan merkittävää vaikutusta. Yhteenvetona voidaan todeta, että mikrobi- ja kastematoyhteisöt pysyvät yleensä vakaina biohiiltä käytettäessä. Tämä mahdollistaisi biohiilen käytön mm. hiilen sitomiseen ja maaperän hedelmällisyyden lisäämiseen maaperän eliöstöä vahingoittamatta. Lisätutkimusta kaivataan kuitenkin erityisesti boreaalisilla alueilla sekä biohiilen ja pääviljelykasvin mahdollisista vuorovaikutuksista. Tutkia kannattaisi myös mahdollisuuksia käyttää biohiiltä yhdessä muiden orgaanisten käsittelyjen, kuten lannan tai kompostin kanssa biologisen monimuotoisuuden ja sadon parantamiseksi.
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(2024)Agnico Eagle Ltd. gold mine in Kittilä, Northern Finland has released treated process and dry-ing waters into River Loukinen since December 2020. The effects of incoming mine discharge waters to brown trout behavior and movements in the river were studied for the first time in 2021. The monitoring was repeated in 2023 according to the terms of the environmental permit. The results of the 2023 study were used in this master’s thesis for determining whether the mine discharge waters affect brown trout behavior by causing avoidance of the area, migration hindrance, or changes in movement activity in the vicinity of the discharge pipe. Electrical con-ductivity (EC) was used as an indicator of the water quality changes caused by the discharge water. Twenty brown trout equipped with external transmitters were released at the site of the discharge water pipe in River Loukinen. Fish movements were tracked for 49 days in August - October 2023 with 11 stationary receivers and occasional location of individual fish with a hand-held receiver while boating in the river. Observation of bypasses and fish movement activity were specifically targeted within the discharge area by mounting several receivers in the vicinity of the pipe. Water quality of the river was monitored above and below the discharge pipe, to determine the level of impact of the discharge waters on river water and its possible effects on fish behavior. The river area below the discharge pipe seemed to be favorable habitat for brown trout with moderate flow rate and heterogenous bottom. Several individuals spent long periods below the discharge pipe regardless of the continuous EC impact of the discharge waters. Many of the monitored brown trout moved widely in the river and even to the main river (11 km downstream) yet returning to the vicinity of the discharge pipe. The results indicate no evident disadvantage or altered behavior of brown trout even under the direct influence of mine discharge waters. However, there was some indication of lower movement activity during periods of higher or increasing EC and decreasing river flow, but this is most likely due to the observed strong negative correlation between flow and EC. Increasing river flow is generally known to enhance fish movement. Even if the EC measurements downstream of the discharge pipe were higher than the natural EC of the river, studied brown trout seemed to behave in a species-typical way considering the habitat preferences and seasonal variations, and the mine discharge waters showed no clear impact on fish movements.
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(2023)Suot ovat tärkeä osa maailmanlaajuista hiilen kiertokulkua, koska ne varastoivat suuria määriä hiiltä eloperäiseen materiaaliin turpeen muodossa, joka muodostuu biomassan hitaasta hajoamisesta kylmän, hapettoman ja matalan pH:n ympäristön vuoksi. Soista vapautuu myös metaania (CH4), joka on voimakas kasvihuonekaasu, jonka lämmityspotentiaali on 28 kertaa voimakkaampi kuin hiilidioksidin (CO2). Turvemaiden netto-C-päästöt riippuvat suotyypistä ja ympäristöolosuhteiden muutoksista, kuten pohjaveden korkeudesta tai turpeen lämpötilasta, ja niistä johtuvasta tasapainosta CH4-päästöjen ja turpeen muodostumisesta johtuvan hiilinielun välillä. Tämän tutkimuksen tavoitteena oli selvittää, miten kasviyhteisöt ja muut säätelevät tekijät, kuten lämpötila, pohjaveden korekus, LAI ja suotyyppi vaikuttavat sekä ilmakehän hiilivirtaan että turpeen CH4- ja CO2-pitoisuuksiin. Lisäksi tehtiin stabiiliin hiili-13 isotoopin mittauksia, jolla saadaan lisätietoa metanogeneesin biogeokemiasta. Mittaukset otettiin rahkasammalvaltaisista mättäistä ja saravaltaisista välipinnoista. Mittauspisteille tehtiin kolme kasvillisuuden manipulointia, joilla selvitettiin kasvillisuuden vaikutuksia hiilidynamiikkaan 1. putkilokasvien ja sammaleiden poisto, 2. pelkkä putkilokasvien poisto, 3. Kaikki kasvillisuus tallella. Tutkimuspaikka sijaitsee Etelä-Suomessa Siikanevan suoalueella. Mittaukset tehtiin vuonna 2018 touko-syyskuussa ombrotrofisessa keidasrämeessä ja oligotrofisessa saranevassa. Mittauskausi oli poikkeuksellisen kuiva ja pohjavedenkorkeus oli keskiarvoa matalammalla. Tästä johtuen monia aikaisemmin havaittuja korrelaatioita ei löytynyt. CH4-virtojen suuruus riippui suotyypistä ja kasvillisuuden manipuloinnista. Keskimääräiset turpeen CH4 ja CO2 pitoisuudet olivat hieman korkeammat mittauspisteissä saranavevalla. Pitoisuudet kasvoivat nopeasti syvyyden myötä, 50 cm:n syvyydessä pitoisuudet olivat useita suuruusluokkia suurempia kuin 7-20 cm:n syvyyksissä korkeimpien, mittausten ollessa yli 500 000 ppm. δ13C-CH4-arvot muuttuivat negatiivisemmiksi tyypillisesti syvyyden myötä, kun hydrogenotrofinen metanogeneesi yleistyi. Kasvillisuuden manipuloinneilla oli vaihtelevia vaikutuksia CH4-vuohon, eikä lehtipinta-alaindeksi osoittanut vahvaa lineaarista korrelaatiota CH4:n kanssa. CH4-virtaus oli myös epäherkkä pohjaveden korkeudelle, mutta kasvien välittämä CH4-kuljetus ei todennäköisesti ollut syynä, koska kasvillisuuden poistokäsitellyt mittauspisteet osoittivat myös samanlaista epäherkkyyttä veden korkeudelle. Putkilokasvien ja sammaleiden poistaminen vähensi yleensä CH4-virtoja. Mättäissä, joissa putkilokasvit oli poistettu, mutta sammaleita ei, oli alhaisimmat CH4-virrat. Yhteenvetona voidaan todeta, että useimmat ympäristömuuttujat eivät osoittaneet vahvaa korrelaatiota CH4:n kanssa. Mikään yksittäinen muuttuja ei selittänyt selvästi eroja CH4-vuossa. Turpeen CH4 ja CO2 pitoisuudet riippuvat voimakkaasti syvyydestä ja suotyypistä. Kasvillisuuden poistaminen tyypillisesti vähensi CH4-virtoja.
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