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  • Purkamo, Lotta (Helsingin yliopisto, 2015)
    Microbial life in the deep subsurface contributes significantly to overall biomass on Earth. Although the microbial communities inhabiting the deep subsurface are abundant, little is known about their diversity, activity, interactions and role in global biogeochemical cycles. The diversity of microbial life in the deep terrestrial subsurface of the Fennoscandian shield was studied with molecular biological methods. The Outokumpu Deep Drill Hole provides access to crystalline bedrock fluids that are estimated to be tens of millions of years old. Characterization of the indigenous bacterial and archaeal communities in addition to microbial communities with important functional properties in bedrock fluids was done from a depth range of 180 m to 2300 m. Microbial community profiling and assessment of possible functional processes was done with molecular fingerprinting, cloning and sequencing methods combined with suitable statistical and bioinformatics analyses. Low cell numbers but high diversity was characteristic to the microbial communities of the Outokumpu deep subsurface. The microbial communities in the fracture zones had in general fewer cells than those in the mixed fluids of the drill hole. Comamonadaceae, Peptococcaceae and Anaerobrancaceae were prevalent bacterial members of the microbial communities in the fracture fluids. Archaea were a minority in microbial communities. Sulfate-reducing bacteria and methanogens were detected at several depths. Microbial communities resembled those detected from other deep Fennoscandian Shield subsurface sites. Furthermore, sulfate reducing communities and archaeal communities resembled those found from the deep subsurface of South Africa. Investigation on carbon assimilation strategies of the microbial communities revealed that mainly heterotrophic Clostridia were responsible for CO2 fixation in this habitat. Representatives of Burkholderiales and Clostridia formed the core microbial community and these were also identified to be the keystone genera. The microbial communities of Outokumpu fractures share similarity with those of serpentinization-driven ecosystems. Energy and carbon substrates formed in serpentinization reactions of ophiolitic rocks in Outokumpu may sustain the microbial communities in this deep subsurface environment.
  • Keriö, Susanna (Helsingin yliopisto, 2015)
    During their life, conifers are attacked by fungal pathogens and insects. In the European forests, Heterobasidion annosum sensu stricto (s.s.) attacks Scots pine (Pinus sylvestris) roots, whereas Heterobasidion parviporum causes the majority of decay in Norway spruce (Picea abies), both causing severe economic losses. Another significant health problem of Scots pine is caused by Hylobius abietis, the large pine weevil, which damages newly established Scots pine stands. Several defence reactions in trees are activated upon fungal infection and insect attack, but these reactions have not been comprehensively studied in conifers. In this dissertation, the responses of mature Norway spruce and Scots pine trees to Heterobasidion spp. inoculation, and the responses of Scots pine saplings to Hylobius abietis feeding were studied. Also the ability of homokaryotic Heterobasidion spp. isolates to infect mature conifer hosts and elicit defensive responses was investigated. Terpene and transcript profiles of Scots pine to H. annosum s.s. and H. abietis challenge were studied, and a customised oligonucleotide microarray with 36.5K cDNA elements designed based on the P. taeda transcriptome was used to study the Scots pine transcriptome. The used homokaryotic Heterobasidion spp. isolates were able to colonize and evoke defence responses in the host trees with varying levels of susceptibility. Insect feeding and fungal inoculation induced terpene production in Scots pine. The results indicated that high accumulation of terpenes is not necessarily an effective defence against H. annosum, but δ-3-carene might be associated with higher tolerance to H. annosum in Scots pine. Only few genes related to terpene synthesis were induced in response to H. annosum infection and weevil feeding. Induction of genes related to biotic and abiotic stress responses indicated a wide transcriptomic reprogramming in response to fungal infection and weevil feeding. Genes related to signal perception and defence responses were induced especially in the trees less susceptible to H. annosum inoculation. In addition to these genes, Scots pine δ-3-carene synthases are promising candidates for further research on the Scots pine resistance to H. annosum.
  • Aalto, Juho (Helsingin yliopisto, 2015)
    Boreal forests are the most significant source of volatile organic compounds (VOCs) in Northern Europe, emissions originating both from trees and forest floor. The VOCs are reactive trace gases that participate in chemical reactions in the atmosphere, thus affecting aerosol formation and climate. The overall aim was to characterize the temporal and spatial variability of VOC emissions and explain the processes and phenomena affecting those. Extensive field measurements were used, including both gas chromatograph and mass spectrometer as VOC analyzers. A dynamic enclosure method was utilized in measuring VOC fluxes from the forest floor and emissions from Scots pine shoots. The genetic background determines the blend of terpenoids emitted by Scots pine, thus having effect on the atmospheric composition. Forest floor and soil also has substantial effect on VOC fluxes on the ecosystem scale. In addition to the considerable spatial variation in VOC fluxes from the forest floor, there is variation of VOC emissions from Scots pine shoots; differences were associated with needle age, seasonality and growth processes. New foliage dominates the VOC emissions from Scots pine foliage during spring and early summer, when growth processes release significant amounts of VOCs, especially monoterpenes. Scots pine shoots are a strong source of monoterpenes during the early stages of photosynthetic recovery; these periods last from a couple of days to about one week and are likely related to the protection of evergreen foliage against photo-oxidative stress. The studies challenge the presumption of constant emission capacities, which is currently a common presumption in VOC emission inventories. Atmospheric concentrations of VOCs result from an output of the existing sources and their seasonal and spatial variation; this underlines the relevance and importance of details on large a scale. The findings provide new opportunities for developing VOC emissions models based on underlying physico-chemical processes.
  • Immonen, Aino-Maria (Helsingin yliopisto, 2015)
    This study investigates the manifestation of emotional influences in the context of two different instances of consumer food choice: price vs. ethicality trade-off decisions in everyday food purchase decision contexts, and the acceptance of genetically modified food products. This study has a particular emphasis on the intricacies that can be uncovered in the emotional influences, by putting focus on the unique compositions and motivational properties of different discrete emotions, and the anomalies and tensions that emerge when mixtures of emotions are experienced. The theoretical background of this study draws from emotion literature, previous research on consumer emotions, and consumer food choice. As a result of a literature review on these topics, this study proposes four key conceptual dimensions that need to be identified and defined in order to gain a better understanding of the role of discrete emotions in particular contexts of consumer food choice. The empirical investigation of this study was conducted with a quantitative approach. Two sets of consumer data (N = 855; 267) were acquired by means of survey questionnaires. The data were analysed with SPSS- and LISREL-softwares by using correlation analysis, analysis of variance, analysis of multiple mediation, moderation analysis, and structural equation modelling. The findings indicate that the salience of an explicit price vs. ethicality trade-off in food purchase decisions induces mixed consumer emotions. This emotionally ambivalent experience has an attenuating effect on the favourability of consumer responses to ethical food purchases with a premium price, but also to unethical food purchases that appeal to consumers with a low price. The findings also indicate that the specific combinations of discrete positive and negative emotions that arise in response to the two types of price vs. ethicality trade-offs are qualitatively distinct. This notion allows for identifying discrete emotional drivers that motivate and inhibit ethical and unethical food purchase decision-making among consumers, particularly when ethical product characteristics are being evaluated against the product price. The findings in the second empirical context of this study outline two distinguishable consumer response patterns to genetically modified (GM) food products, which are intertwined with consumers fearful and angry responses to the genetic modification of food (the GM of food). The findings indicate that the fear and anger that consumers experience towards the GM of food are rooted in different types of substantive concerns, and fearful and angry consumers have a preference for distinct modes of coping with the perceived threat of GM food products. The findings have implications for disentangling the nuances of the affectively toned consumer opposition that exists towards the GM of food and GM food products, and for interpreting their distinct impacts on the prospects of GM foods in the consumer market.
  • Jokela, Venla (Helsingin yliopisto, 2015)
    Timothy (Phleum pratense L.) is one of the most important forage grass species grown at high latitudes. Its sward canopy structure determines the quantity and quality of the silage yield. Nonetheless, processes behind the transition to flowering, as well as the formation of stems and the connection with forage quality have not been studied in detail for timothy. Seven experiments were conducted to explore the effect of vernalization, photoperiod and gibberellin treatments on flowering and canopy structure in different cultivars or accessions. In addition, the expression of key regulator genes, VRN1 and VRN3, as well as the flowering repressors VRN2 and MADS10 were studied, and the connection between these and flowering induction and stem formation was revealed. Results showed that photoperiod is the most important regulator of flowering in timothy. In addition, vernalization response was reported in most of the tested accessions, which was seen as faster flowering. It was found that the application of GA3 could not replace the LD requirement for flowering. Moreover, results showed that the requirement for flowering and stem elongation vary. Flowering is also associated with decreased digestibility of grass stems. Our results showed, however, that flowering induction was not required for the development of the lignified sclerenchyma ring in developing stems, but rather lignin accumulation was as a result of stem elongation and requirements for mechanical support. At molecular level, novel vernalization-related partial cDNAs were identified through sequencing. Both PpVRN1 and PpVRN3 homologs induced the transition to reproductive development, but PpVRN3 was required for flowering. These results support the theory of universal flowering-promoting system between species. The expression of the putative repressor homolog, PpMADS10, was connected to the developmental stage of the apex. Results obtained in this thesis shed new light on the regulation of flowering and canopy structure in timothy. It is concluded that large variation exists among accessions in their responses to vernalization and photoperiod. This information can be utilized in breeding for high-yielding new cultivars for different growing conditions at high latitudes and for different harvesting strategies.
  • Korpunen, Heikki (Helsingin yliopisto, 2015)
    Finnish forest industry purchases 50 million cubic meters of wood annually. This means that the economic importance of the business is significant to forest owners. Sawmills, pulp and paper industry, and energy production are most common targets of the wood raw material. It is in mutual interest of both forest owners and the industry that the wood is allocated to right use according to the highest possible value-adding. The path of wood from forest to customers can be described as a value chain where the links are formed of harvesting and forwarding, long distance transportation, wood processing and energy use, and delivery to final customers. This dissertation focuses on the links of wood processing and energy use of the wood value chain by modelling production and costs of sawmill, pulp mill, paper mill, and combined heat and power (CHP) plant. The modelling was done by using activity-based costing (ABC), where the production is divided into processes and the production costs of each process are allocated to products or services according to resource consumption. Finally, all process costs are summed for total production costs of each cost object. The production and cost models were tested with virtual mills. The processes, the resources and the necessary cost factors of production were determined for test calculations. Finally, the capital, the labor, and the energy costs were allocated to the cost objects, which were both the raw materials and the end products. When comparing different mills and their production processes, it was noticed clearly that drying was an expensive process in sawmilling, pulping and papermaking. When focusing on cost factors of each mill, it was noteworthy that the sawing pattern affects the costs of a sawmill, energy production affects the costs of pulp and paper industry, and, likewise the utilization rate affects the combined heat and power plant. Profitability analyses were also made on the pulp mill, the paper mill and the CHP plant in varied market situations. One key finding was that in papermaking, the change of market price of paper was more significant to economics of the mill than a similar change in the market price of energy. The results of this dissertation can be used in estimating the economic performance of forest industry. Process-based approach helps in finding possible bottlenecks and in developing the production systematically. The findings of this study can also be used in finding the most profitable route for wood from the forest to customers.
  • Klimeski, Aleksandar (Helsingin yliopisto, 2015)
    Deterioration in the quality of surface waters worldwide is associated with losses of phosphorus (P) from diffuse sources. Controlling such losses is rather difficult, but their significance in reducing the effects of eutrophication is crucial. Phosphorus losses from diffuse sources represent a significant share of total P transfers to surface waters. Researchers have studied and implemented numerous methods to curb non-point P losses during the past decades, but such studies have generally been insufficient to change the impact of agriculture on the course of surface waters eutrophication. For example, even though inputs of P and nitrogen (N) into the Baltic Sea have significantly decreased over the past two decades, the Baltic Sea still represents a eutrofied body of water. To further reduce P losses from agriculture, current P abatement methods must be amended with additional techniques. One such technique involves the use of P-retaining materials as filters placed in ditches within agricultural areas. This study encompasses a set of laboratory, meso- and large-scale set-ups to identify potential P-retaining materials available in Finland for the treatment of agricultural runoff. The laboratory studies investigated the P retention potential of fresh and weathered Ca-rich (Sachtofer PR®, steel slag, Filtra P®, Filtralite P®) as well as Fe-rich materials (mine drainage residual - MDR) in flow-through tests when applying a high influent P concentration of 50 mg/l. The weathering process served to leach out soluble species such as Ca2+ and OH-, thus mimicking aged filters. In addition, desorption/dissolution tests involved the placement of P-saturated materials in solutions of variable pH as well as one-month extraction with large volumes of water. Sachtofer PR®, steel slag, Filtra P® and MDR retained relatively large amounts of P, varying between 12 and 24 mg P/g material. As desorption/dissolution tests show, two distinct mechanisms controlled the materials retention of P: precipitation of Ca-phosphates and sorption of P onto Fe-hydroxide surfaces. As the most promising material, Sachtofer PR® was further employed in meso- (20 kg) and large-scale (7 tons) filters that treated influents with significantly lower P concentrations, up to 6 mg/l and 0.25 mg/l, respectively. The feed solution in the meso-scale filter alternated between P-enriched tap and river waters, whereas the large filter treated agricultural runoff from 17 ha of cropland. As the application of Sachtofer was scaled up, and influent P concentration declined, cumulative P retention decreased from 19 mg P/g in the laboratory to 0.06 mg P/g in the field. The meso-scale experiment indicated that the P removal efficiency decreased also due to the presence of dissolved organic carbon (DOC) in the influents; the filter retained about 10% of the total amount of DOC added to the system. As for the large filter, the formation of preferential water pathways resulting from material decomposition and freezing-thawing cycles greatly reduced its efficiency. Moreover, in high flow conditions during spring snowmelts or high rainfalls, the large filter treated only a small portion of the incoming flow; the estimated treated flow during the entire test period was about 20%. Maintaining a low effluent limit is rather challenging, and such techniques should instead serve to remove a significant part (e.g., 30-40%) of the dissolved mass of P in agricultural runoff. To justify the potential P recovery from spent filters and to ensure cost-efficiency, the P-retaining material should reach a significant P saturation. In addition, P removal structures should be coupled with other best management practices to minimize losses of P from agriculture. Keywords: P-retaining materials, P retention, precipitation, sorption, upscaled application, dissolved organic carbon, material alteration, preferential flows, high flows, filters, permeable reactive barriers
  • Epie, Kenedy Etone (Helsingin yliopisto, 2015)
    The increasing use of fossil fuel is plagued with problems leading to interest in alternative sources of energies. Bioenergy or biomass energy remains today s important renewable energy source that can contribute to reducing the overall consumption of fossil fuel and can move energy systems towards sustainability and supply security. However, doubts on sustainability impede the acceptance of bioenergy. Hence, the sustainable cropping of reed canary grass (Phalaris arundinacea L., RCG), an established perennial energy grass, was studied. Important sustainability criteria were considered, namely; land use, biomass productivity, emission of greenhouse gas nitrous oxide (N2O) and biodiversity. The general aim of the study was to develop farming methods that would provide biomass feedstock of RCG in a sustainable manner. Field and glasshouse experiments were carried out at the University of Helsinki, Finland, during 2008 to 2013. The suitability of problematic acid sulphate soils managed with raised water tables for cropping RCG was investigated in lysimeter experiments. Growth parameters were measured and biomass yield and energy qualities were determined. In field conditions with soils classified as Gleyic Stagnosol, RCG was supplied with N from inorganic fertilizer and N fixed into soil by intercropped legume galega (Galega orientalis Lam.) and its biomass yields and mineral element composition and other energy qualities were determined. Gases were collected from these fields using closed chambers and greenhouse gas N2O emissions were analysed by gas chromatography. The crop and crop mixture effects on earthworm communities were determined by the extraction of earthworms using mustard oil and manual separation from soil. Reed canary grass grew well in acid sulphate soils and even performed better by producing more biomass with better quality when the water table was raised to reduce acidity and to avoid environmental hazards. Carbon was also sequestered into the soil by RCG root biomass. In the field experiment, RCG galega mixtures produced equally good biomass yields and of better energy quality than the fertilized RCG counterpart. The annual cumulative emissions of N2O from mixtures were marginally lower than those from fertilized RCG soils. Although fertilized RCG produced twice as much biomass and correspondingly higher nitrogen and energy yields, its low emission of N2O per ton of dry matter or per unit of harvestable bioenergy was not significantly different from that of the mixtures. Mixtures also enhanced earthworm abundance and species numbers compared to pure RCG stands. Therefore cropping an RCG galega mixture for biofuel may supply a good quantity of biomass feedstock, result in lower N2O gas fluxes, and sustain earthworm biodiversity but requires management to maintain grass as the major component. Using managed acid sulphate soils for perennial energy cropping will help to reduce the tension between food and energy crop production over arable land and may improve the negative perception of bioenergy as a whole. A 25% Galega- 75% RCG mix has the potential to replace N fertilizer input during energy crop cultivation, meaning reduced cost of production and more income for energy crop farmers. Moreover soil macrofauna diversity will be conserved. With reduced N2O gas emission, this grass-legume mixture could make a significant contribution in mitigating climate change and its effects. All these will come a long way to help in making bioenergy more sustainable.
  • Haltia, Emmi (Helsingin yliopisto, 2015)
    Environmental quality has a direct effect on citizens welfare. To quantify this effect, the four articles of this thesis analyse Finnish citizens willingness to pay (WTP) for increased forest conservation using the contingent valuation (CV) and choice experiment (CE) methods. These methods are based on neo-classical welfare economics augmented with the choice process framework originating from psychology and behavioural economics. Using the CV method, we analyse how WTP is affected by respondents uncertainty, by the share of nonrespondents and by the considerably high share of yes responses at the highest proposed costs to households. The CE data are used to study the effects of different conservation programme characteristics on WTP. The results show that Finnish citizens support increased forest conservation. The median WTP in the contingent valuation was 72 EUR, i.e. 50% of respondents supported increased conservation if the costs per household did not exceed 72 EUR. The mean WTP estimates were sensitive to modelling assumptions and assumptions concerning the nonrespondent preferences. This emphasises the need for careful sensitivity analyses when results are used for welfare measurement and policy planning. Respondents choices in the valuation questions were affected by the household costs of conservation and other socioeconomic characteristics. The results suggest that the choices in valuation tasks are affected by economic and psychological factors. The study gives important insights into the choice behaviour and lower and upper bound estimates of WTP. These estimates are somewhat lower than those in comparable earlier Finnish studies. In CV, respondents seemed insensitive to programme size while the extent of the proposed project had a significant effect on the choices in CE.
  • Chen, Hongxin (Helsingin yliopisto, 2015)
    The basidiomycete white-rot fungus Heterobasidion annosum sensu stricto (s.s.) is one of the most severe conifer pathogens in the Northern Hemisphere. It can live as a saprotroph on dead wood tissues or a necrotroph on living trees. Taking advantage of a sequenced genome from a closely related species, Heterobasidion irregulare, we performed an in-depth transcriptomic analysis of this fungus under various abiotic stresses (temperature stress, osmotic stress, oxidative stress, and nutrient starvation) and during saprotrophic growth on pine bark, sapwood, and heartwood. The results unraveled potential regulatory mechanisms to overcome these conditions. Based on the specific induction in the microarray, cerato-platanins were selected for further study in the interactions between H. annosum s.s. and Pinus sylvestris. As the first step, a genome-wide bioinformatic study of the cerato-platanin family in Dikarya was therefore conducted. The results suggested that they exist in both Ascomycota and Basidiomycota, but were lost in early branches of jelly fungi as well as in some groups with yeast or yeast-like forms in their life cycles. The ancestor of the Dikarya possessed multiple copies of cerato-platanins, which sorted differently in Ascomycota and Basidiomycota, and this gene family might have expanded in Basidiomycota. To gain insight into the role of cerato-platanins as potential virulence factors in H. annosum s.s., we performed the functional study of HaCPL2 by using a recombinant protein produced in Pichia pastoris. Interestingly, HaCPL2 was able to induce cell death in both host (P. sylvestris) and non-host (Nicotiana tabacum) plants. Besides cell death symptoms, HaCPL2 retarded apical root growth of P. sylvestris seedlings and induced phytoalexin production in N. tabacum. Defense-related gene expression was also upregulated in both plants after HaCPL2 treatment. This study has provided valuable information about potential gene regulatory mechanisms in H. annosum s.s. that mediate stress adaptation and growth in different pine wood compartments. Moreover, we propose that HaCPL2, a cerato-platanin protein, could act as an effector and contribute to the virulence in the H. annosum s.s.–P. sylvestris pathosystem. This furthers our understanding of Heterobasidion pathogenesis and provides a future target for disease control.
  • Kymäläinen, Maija (Helsingin yliopisto, 2015)
    The need to replace fossil fuels with renewable energy sources has become an increasingly important field of research and development in order to combat the global climate change. Wood is a well utilised and much studied source of energy that has some inherent problematic characteristics common to all lignocellulosic biomass. Moisture affects the entire supply chain of wood fuels negatively by complicating transport, handling, storage, and combustion. During storage, the wood takes up moisture, which leads to fungal deterioration and consequently losses of heating value. The problem has been addressed by reducing the hygroscopicity of wood through the thermal pre-treatment process of torrefaction. In addition to hydrophobicity, torrefaction leads to other beneficial characteristics that are expected to improve the performance of lignocellulosic biomass in logistics and combustion. Due to hydrophobicity the material is said to be resistant to fungal degradation and subsequent dry matter losses. The combustion would be efficient without the need to evaporate water that can form up to 60% of untreated woody biomass. However, only few studies exist, and the material s performance in storage has been pointed out as an important research area. To tackle this challenge, this thesis aimed to provide much needed answers related to the storage properties of torrefied wood and charcoal, most importantly the effect of moisture. This thesis is made up of four studies, in which the sorption properties and fungal degradation of torrefied spruce and birch, as well as charcoal produced from the same feedstock, were investigated. In one experiment torrefied pellets and steam explosion pellets were compared with the undensified material. It was found that the pyrolysed material adsorbed only minor amounts of water vapour both in laboratory experiments as well as in an outside storage trial. The hydroxyl group accessibility and the particle size of the material were also reduced. However, although the capillary absorption was slower, the capacity for water uptake was increased. This led to high moisture contents during the storage trials. It was also shown that the material can serve as the sole carbon source and is therefore subjected to fungal degradation. The degradation was slow, but significant dry matter losses were recorded from certain samples in laboratory conditions. Furthermore, the fungal activity increased the material s moisture content. The torrefied material hosted abundant fungal flora following outside storage trials, and many of the identified genera were known allergens. Also it was shown that torrefied pellets do not tolerate contact with water. Many of the properties of torrefied wood are favourable in terms of easier handling and improved combustion behaviour. However, the results presented in this thesis show that the storage of the material may not be as easy as speculated. The torrefied wood, whether as chips or pellets, should be stored in covered areas and direct contact with water should be avoided. The working safety issues should be carefully addressed to avoid unnecessary exposure and accidents when handling the pre-treated material.
  • Ramos Diaz, Jose Martin (Helsingin yliopisto, 2015)
    Amaranth (Amaranthus caudatus), quinoa (Chenopodium quinoa) and kañiwa (Chenopodium pallidicaule) have been cultivated in the Andean region of South America since Pre-Hispanic times. They are regarded as formidable nutritious alternatives due their high content of protein (rich in lysine), dietary fibre and bioactive compounds such as tocopherols, phenolic compounds and folate. Despite this, the academic research conducted on their utilisation for human consumption is relatively low. Conversely, lupine (Lupinus angustifolius) is a well-known legume used for animal feed in most of the Nordic countries. The aim of this research was to incorporate amaranth, quinoa, kañiwa and lupine to corn-based snacks, and study their physical, chemical and sensory properties. A co-rotating twin screw extruder was used to obtain corn-based extrudates containing amaranth, quinoa, kañiwa and lupine. In preliminary studies (incorporation up to 20% of solids), Box-Behnken experimental design with three predictors was used: water content of mixture (WCM, 15-19%), screw speed (SS, 200-500 rpm) and temperature of the die (TEM, 150-170 °C). Subsequent studies were conducted using partial least squares regression (PLSR) and L-partial least squares regression (L-PLSR) with nine predictors: Grain type, grain content (20-50% of solids), temperature of die (140-160 °C), screw speed (200-500 rpm), water content of mixture (WCM, 14-18%) as well as contents of protein, ash, fibre and sum content of main fatty acids of blend. In general, WCM and screw speed had the greatest importance for response variables such as torque and pressure at the die during extrusion, sectional expansion index (SEI), stiffness and water content of extrudate; the content of protein and dietary fibre in the blend was particularly relevant during the extrusion of extrudates containing kañiwa and lupine. Regarding the most expanded extrudates, those containing 20, 35 and 50% amaranth, quinoa or kañiwa presented comparable SEIs and stiffness while those containing above 20% lupine suffered from structural collapse. Extrusion reduced the content of fatty acids and tocopherols in the solids but it had a slight effect on the content of total phenolic compounds and folate. In sensory studies, extrudates with higher contents of amaranth, quinoa and kañiwa were rated less crispy, less crunchy and less adhesive with less hard particles. Temporal analysis showed that with increasing contents of amaranth, quinoa and kañiwa, crispiness and crunchiness became the most dominant attributes during mastication while the dominance of roughness reduced considerably. Porosity and wall thickness, measured by X-ray microtomography, were linked to the perception of crispiness and crunchiness, respectively. In storage, whole extrudates containing 20% amaranth, quinoa or kañiwa and exposed to RH of 76% presented the lowest formation of hexanal compared to milled extrudates exposed to RH of 11%. This study showed that expanded corn-based extrudates containing up to 50% amaranth, quinoa and kañiwa and at most 20% lupine of solids can maintain key mechanical and textural properties as well as added nutritional value. This study applied successfully PLSR and L-PLSR modelling techniques to study the incorporation of amaranth, quinoa, kañiwa and lupine to corn-based snacks. This research has expanded the knowledge linked to the development of gluten-free extrudates with added nutritional value.
  • Zou, Ling (Helsingin yliopisto, 2015)
    Factors limiting barley yield have been reduced since the Green Revolution globally. Nevertheless, higher yields are pursued with the pressure to feed the increasing human population and domestic animals. However, sustainability can be impaired by the cereal monocultures, in particular, cereal-specific pathogen inocula can increase at the cost of diversity of soil microfauna. Use of pesticides has selected for resistance in weeds and pathogens. Use of mineral fertilizers has resulted in waste of resources and pollution. In Finland, about half of the arable land is used for continuous cereal production, and barley (Hordeum vulgare), as an important source for food and feed, is the most cultivated cereal crop. In this dissertation, research focused on evaluating the effects of various rotation crops on weeds, pathogenic fungi, soil fertility and yield of subsequent barley. The competitive ability of six crops, namely buckwheat (Fagopyrum esculentum), caraway (Carum carvi), faba bean (Vicia faba), hemp (Cannabis sativa), common vetch (Vicia sativa) and white lupin (Lupinus albus) with weeds was evaluated in glasshouse and field experiments. In the glasshouse experiment, couch grass (Elymus repens) grown with buckwheat accumulated the least dry matter. Activated charcoal was used to exclude the effect of root exudates from donor crops. The results indicated that activated charcoal incorporated in the soil deactivated buckwheat root exudates that apparently inhibited the growth of couch grass. In the field experiment, buckwheat s fast growth and formation of effective leaf area inhibited growth of weeds most effectively among the crops tested. The effect of turnip rape [Brassica rapa L. ssp. oleifera (DC.) Metzg.] on several soil pathogenic fungi was evaluated in a field trial in two growing seasons involving five different cultivation regimes: mixed culture of barley and turnip rape, turnip rape sown after barley, and turnip rape incorporated as green manure either in autumn or in spring, with continuous barley monoculture as a control. Soil fungal community structure was monitored with capillary-based LH PCR of the ITS region using primers ITS1F/ITS4. The mixed culture and sowing turnip rape after barley did not significantly decrease the relative abundance of Fusarium spp. Incorporation of turnip rape plants into the soil, as a source of organic matter and nutrients, was associated with a low relative abundance of Fusarium spp. Fungal diversity was the lowest and the relative abundance of Fusarium spp. the highest in continuous barley. Higher fertilizer application and organic matter incorporation, leading to high fungal diversity, seemed more important in affecting Fusarium spp. than the allelochemicals of turnip rape, as turnip rape extracts did not detectably inhibit the growth of F. culmorum in an in vitro test. In growth media of different nutrient levels, 10 g soil were suspended in 100 mL sterile water, then 400 μL of the suspended solution was spread on the media of each nutrient level with four replicates. The number of fungal colonies was counted. The soil Fusarium CFU count was higher on nutrient-poor growth medium than on rich medium, supporting the results of field experiments. Results of sequencing indicated that Penicillium spp. might also tolerate low nutrient availability. In two experiments that ran 2010-2012 and 2011-2013, faba bean, turnip rape and barley were sown as first crops and their residues were tilled into the soil after harvest in blocks in the first year. In the following year, barley, buckwheat, caraway, faba bean, hemp and white lupin were sown in each block and incorporated either at flowering stage (except barley) or after harvest. Barley yield and grain protein concentration were determined. Mineral N concentrations in the plough layer two months after incorporation of crops and before sowing barley in the following spring were determined. In the third year, all the plots were sown with barley. The beneficial effect of faba bean and turnip rape, as first crops, on yields and grain protein concentration of barley was still detectable in the third year. Barley yields after white lupin, faba bean and hemp, as second crops, were higher than in continuous barley. Barley grain protein concentration was increased after faba bean. In contrast, barley yield and grain protein concentration were not improved after buckwheat and caraway. Incorporation of plants at flowering stage posed a risk of increased N leaching, suggesting that incorporation of plants should be delayed or catch crops should be used during winter to reduce N leaching. The response of barley yields to increased mineralized N from green manure or residues after harvest of rotation crops was significant only in the first experiment conducted in 2010-2012 suggesting that increased mineral N in the plough layer has minor influence on barley yield. Thus, rotation with faba bean, white lupin and hemp was beneficial to barley grain yield. In addition, barley grain protein concentration was increased after rotation with faba bean. Weed growth was most strongly suppressed by buckwheat as a complement to current weed management regime, but, rotation with buckwheat and incorporation of its residues did not improve the yield of the successive barley. The effect of glucosinolates of turnip rape on soil-borne pathogens was outweighed by high fungal bio-diversity suggesting that allelochemicals released from plants sown at a realizable density in the field are unlikely to control pathogens. Maintaining high microbial diversity through sufficient nutrient input is crucial to control pathogenic Fusarium spp. populations.
  • Zhang, Yanlei (Helsingin yliopisto, 2015)
    Type 2 diabetes occurs as a consequence of aging, family history, physical inactivity, unhealthy diet and obesity and it is an increasing public health problem worldwide. The condition is associated with high rates of mortality from co-morbid cardiovascular diseases and poor health-related quality of life (HRQoL). A large proportion of individuals with type 2 diabetes are not diagnosed for up to a decade after onset unless a screening programme has been implemented. The estimated prevalence of undiagnosed diabetes in China accounts for about 60-70% of the diabetes population. Diabetes education that is targeted at the general population is the key to increase public knowledge and awareness and is a fundamental building block for addressing the diabetes epidemic. Screening for identifying undiagnosed diabetes could lead to earlier identification and intervention, and postpone or prevent the onset of diabetes and its complications. However, there is a paucity of study on the impact of education and screening programmes on HRQoL, lifestyle modification of the targeted population, and the cost-effectiveness of such programmes. The objectives of this study were to investigate 1) the cost and effectiveness of a population-based education programme to increase public knowledge and awareness of diabetes; 2) the cost-effectiveness of two different screening tools for undiagnosed diabetes; 3) impact of type 2 diabetes and its complications on individuals HRQoL; 4) impact of a screening programme on individuals overall HRQoL, depression dimension and lifestyle modification. This study was based on data analyses of two population-based diabetes surveys conducted in 2006 (Survey A) and 2009 (Survey C), and a dataset of diabetes high-risk population identified through the Qingdao Diabetes Prevention Program (QD-DPP) between 2007 and 2010 in Qingdao, China (Survey B). The same stratified, random cluster sampling method was used in Surveys A and C to recruit a representative sample of the general population who had lived in Qingdao city for at least five years. A total of 5355 individuals in Survey A and 5110 in Survey C aged 35-74 years participated in the surveys. A total of 3108 rural participants who did not have diabetes at baseline in 2009 were invited for a re-examination and 1782 individuals attended the follow-up survey. A standard 2h 75g oral glucose tolerance test was administrated to all participants in both surveys. Diabetes education and health promotion information and activities under the framework of QD-DPP were given via printed and audio-visual media, the internet, free distribution of information booklets and diabetes risk score (DRS) flyers that targeted the entire population of 1.94 million who lived in the intervention areas. An adult with a DRS more or as much as 14 was considered at high-risk for diabetes and invited to a nearby community clinic for a free capillary blood glucose test. The proportions of participants who correctly marked obesity, physical inactivity and positive family history of diabetes as the risk factors of diabetes were doubled in both urban and rural populations, irrespective of age and gender during the QD-DPP education campaign period. The cheapest way to inform 1000 individuals about type 2 diabetes was to distribute DRS flyers (¥54, ¥ = Chinese yuan), followed by the newspapers articles (¥77), booklets (¥313) and by radio programmes (¥375) (1 ≈7¥, for the year 2015). The fasting capillary glucose (FCG) test and Chinese DRS questionnaire were used as the first-line screening tools and these were evaluated for detecting undiagnosed diabetes in primary care settings. The sensitivity of FCG and DRS was 65.1% and 65.8%, whereas their respective specificity was 72.4% and 55.2%. The costs per undiagnosed diabetes identified at the optimal cut-off values of 6.1 mmol/l for FCG and 14 for DRS were ¥674 and ¥844, respectively. The area under curve (AUC) was higher for FCG than for DRS (75.3% vs. 63.7%, p less than 0.001). People with previously known type 2 diabetes reported that the symptomatic comorbidities had a strong negative impact on HRQoL; no significant difference was detected between people without diabetes and with newly diagnosed diabetes. The screening and labelling as pre-diabetes or normoglycaemia had no adverse impact on the participants overall HRQoL and depression. An improvement in lifestyle as measured by the frequency of physical activity and vegetable intake was observed at 3 years post screening in both groups. In conclusion, the QD-DPP education campaign efficiently increased public knowledge and awareness of diabetes. The DRS questionnaire is a simple, non-invasive and reliable first-line screening tool to identify undiagnosed diabetes at primary care settings. The diabetes screening programme in Qingdao generated positive changes towards a healthy lifestyle and did not result in any harm to the participants.
  • Lienemann, Taru (Helsingin yliopisto, 2015)
    Salmonella is one of the most commonly reported foodborne pathogens and enterohaemorrhagic Escherichia coli (EHEC) is one of the most dangerous. They both spread by zoonotic and person-to-person transmission routes. Most Salmonella infections are characterized by mild-to-moderate self-limited diarrhea but also serious disease resulting in death has been reported.Bloody diarrhea is a common symptom of human EHEC infection and the infection may lead to severe post-infection disease such as hemolytic uremic syndrome (HUS), thrombotic thrombocytopenic purpura (TTP) and even death. The purpose of this thesis was to investigate the diversity of Salmonella and EHEC strains isolated from domestically acquired infections using several pheno- and genotyping methods for surveillance and outbreak investigation purposes as well as evaluate certain epidemiological typing methods in Finland. All Salmonella and EHEC isolates of domestic origin during 2007-2014 in Finland were studied. Serotyping, phage typing, antimicrobial susceptibility testing, phenotype microarray, pulsed-field gel electrophoresis (PFGE) and multilocus variable-number tandem repeat analysis (MLVA) were applied as epidemiological typing tools for Salmonella isolates. EHEC isolates were analyzed using serotyping, phage typing, antimicrobial susceptibility testing, virulence gene detection (stx1, stx2, eae, hlyA and saa) and PFGE. During the study period, the number of domestically acquired Salmonella infections has decreased about one fifth compared to the previous decade whereas the number of domestic EHEC infections have increased about one third.Th e incidence of Salmonella infections was highest in 2012 (7.5/100,000 population) and lowest in 2014 (5.4/100,000 population). The incidence of EHEC infections was highest in 2013 (0.33/100,000 population) and lowest in 2008 (0.07/100,000 population). 15% of all Salmonella strains and 70% of all EHEC strains were considered domestically acquired. A total of 131 different Salmonella serovars were detected. The most common serovars were Typhimurium (32%), Enteritidis (15%) and group B (6%). Among Typhimurium strains, phage types DT1 (37%), RDNC (18%) and DT104 (9%) were the most common ones. The most frequently detected phage types among the domestically acquired S. Enteritidis infections were PT8 (17%), PT1B (14%) and PT4 (13%). Th e majority of domestic Typhimurium and Enteritidis (60%) strains were susceptible to tested antimicrobials. During the study period, a total of 188 infections caused by EHEC were detected. Most of them were caused by serotype O157:H7 (60%). The majority of O157 strains (63%) were unable to ferment sorbitol. PT8 was the most common phage type among the sorbitol-negative and PT88 among sorbitol positive O157 strains. Among non-O157, 22 distinct O:H serotypes were detected. The most common ones were O26:H11, O103:H2 and O145:H-. The majority of domestic EHEC strains (81%) were susceptible to all tested antimicrobials: 96% of O157:H7/H- and 60% of non-O157 strains. All O157 strains carried stx2 (40% in combination with stx1), eae and hlyA genes. In contrast, 55% of non-O157 stains had stx1 gene and 76% carried eae and hlyA genes. The MLVA method was found to be a powerful epidemiological tool for S. Typhimurium with discriminatory power similar to PFGE. In addition, MLVA was faster, cheaper and the results were easier to compare between laboratories. The domestic S. Typhimurium strains were divided into 170 distinct MLVA types (diversity index 0.891). In MLVA, the three most common profiles (3-16-NA-NA-0311, 3-15-NA-NA-0311 and 3-17-NA-NA-0311) counted for 47% of the strains showing that the lack of locus STTR6 and locus STTR10p was characteristic for domestic S. Typhimurium. However, XbaI-PFGE remains a useful genotyping method for investigations of other Salmonella serovars and EHEC strains. The interpretation of XbaI-PFGE profiles can be challenging as demonstrated by a Finnish nationwide outbreak caused by S. Newport and S. Reading -contaminated iceberg lettuce. The S. Reading strains had four diff erent XbaI-PFGE profiles. Based on epidemiological information, all these different variants of the outbreak causing strains were considered as outbreak-related. The sources of the most EHEC outbreaks remained undetermined. In one out four EHEC O157 outbreaks, unpasteurized milk was found as the source of the infections. Although 40% of the domestic EHEC strains were non-O157, only strains of serogroup O157 caused outbreaks in Finland. However, non-O157 strains caused several family clusters and were linked with HUS. In 2009, a sorbitol-fermenting EHEC O78:H-:stx1c:hlyA was detected in blood and fecal samples of a neonate. This EHEC serotype had not been seen in Finland prior to this family-related outbreak and bacteremia caused by EHEC is exceptionally rare. Taken together, Salmonella and EHEC infections are a major public health concern. This thesis provides new information about the characteristics of Salmonella and EHEC strains isolated from domestically acquired infections in Finland and evidence that effective surveillance is needed for early detection and prevention of the spread of Salmonella and EHEC infections. In particular, typing methods used should be internationally harmonized and the results made comparable.
  • Détry, Nicolas (Helsingin yliopisto, 2015)
    Oxidoreductases are found in all living organisms and play essential roles in housekeeping, perception of environmental stress, plant-pathogen interactions, defense reactions, and pathogenicity. In particular, laccase, peroxidases and NADPH oxidase, have been implicated in virulence of phytopathogenic fungi in pathogenicity. Despite its relevance towards plant microbe interaction, the identification and comparative analysis of fungal peroxidase-encoding genes at the genomic level have been limited by the lack of a bioinformatics platform as well as paucity of information on transcript profiling of potential candidate oxidoreductase genes. In this project, one of the primary tasks addressed was the construction and development of a new fungal peroxidase database (fPoxDB). The availability of fPoxDB platform facilitated comparative and evolutionary studies of fungal peroxidases at the genomic level. The database contains 6,113 peroxidase genes of 25 gene families from 331 genomes. The archived genes were subjected to pre-computational analyses using eight different bioinformatic tools: SignalP 3.0, SecretomeP 1.0f, TargetP 1.1b, predictNLS, ChloroP 1.1, TMHMM 2.0c, PSortII, and InterPro Scan. Similarity search tools including HMMER, ClustalW, Blast, and BlastMatrix are provided on the platform. A web interface enables researchers to browse the database via either species or class . Graphics support the work and enhance user-friendliness. Retrieved data can be exported to other family web-systems including the comparative fungal genomics platform (CFGP). In parallel to the above study, the second project was focused on in silico comparative analysis fungal NADPH oxidase (Nox) genes sequences. Nox proteins are transmembrane enzymes found in most eukaryotic organisms and influence many biological processes by generating reactive oxygen species (ROS). In fungi, Nox enzymes play roles in pathogenicity, such as the weakening of plant cell walls by ROS. The enzymes exhibit high sequence similarities to the ferric-reductases (Fre) and ferric-chelate reductases (FRO) proteins, which are involved in reduction of Fe3+ to Fe2+ for iron uptake. A total of 34 eukaryotic genomes, covering 28 fungal, one Oomycota, three animal and two plant species, were subjected to bioinformatic analysis. The results indicate that the properties of fungal Nox genes differ from those of the human and plants, providing novel insights that will enable more accurate identification and characterization of the fungal genes. In the third project, as not much is known is about precise role of oxidoreductase encoding genes in pathogenesis, we explored expression profiling of a typical oxidoreductase gene, laccase, in Heterobasidion conifer pathosystem. Laccases are multi-copper oxidoreductases catalyzing the oxidation of phenolic substrates, and they play diverse roles in plants and fungi. In fungi, laccase have been shown to be involved in pathogenicity, as well as in lignin degradation. To understand the potential roles of laccases of the forest pathogen Heterobasidion annosum, a total of 18 laccase genes was identified in this fungus and phylogenetically analyzed. The expression levels of the genes, and laccase activities, during growth of H. annosum on its host in the presence or absence of additional carbon source, such as glucose and sucrose, were investigated. Based on increased transcript expression levels eight laccases were considered to be potentially involved in H. annosum virulence. In summary, we provide the research community with a database dedicated to fungal peroxidases, and our in silico analysis affords new insights in the structure of fungal NADPH oxidases. Lastly, we present experimental evidence that some H. annosum laccases might be involved in virulence during infection of non-suberized Scots pine seedlings.
  • Garlant, Linda (Helsingin yliopisto, 2015)
    This dissertation is aimed at studying the emergence and invasiveness of a new soft rot bacterium: Dickeya solani. Members of the Dickeya genus cause soft rot and blackleg in potato, which is one of the world s most important food crops. D. solani was first isolated in Finland in 2004; since then, it has been identified in many European countries. It most likely emerged in the Netherlands and spread elsewhere in Europe and beyond via the potato seed trade, and it has rapidly became a major threat for potato production, along with the other commonly known soft rot bacteria D. dianthicola and Pectobacterium species. In this study, the ecological aspects and genomics of D. solani were investigated to elucidate the mechanisms underlying its fast spread and high aggressiveness. A real-time PCR test was developed to analyze plant samples containing Dickeya species. This test ensures the fast determination of the amount of Dickeya cells present in symptomatic plant tissue and avoids lengthy and labored procedures for bacterial cell isolation, thereby representing an advantageous diagnostic tool. Biovar 3 Dickeya isolates were biochemically characterized and found to differ from the other known Dickeya species isolated from potatoes and ornamentals in Europe. Taxonomic analysis indicated that these strains belonged to a new species within the genus Dickeya, which was consequently named D. solani. The genome of a Finnish D. solani strain was sequenced to study the invasive character of this new species. Comparative genomic analysis indicated the presence of a set of specific genes involved in the production of toxic secondary metabolites, which triggered the investigation of the ability of D. solani to outcompete other bacterial species present in the potato environment. A newly identified bacteriocin-like molecule produced by D. solani promoted the growth inhibition of some Pectobacterium species, thus partly explaining the rapid colonization and dominance of the potato environment by this novel soft rot pathogen. This study provides novel information about the ecology, taxonomic status and genomics of the new potato pathogen D. solani. This information is likely to contribute to applied studies to improve potato production and plant health in general in the future.
  • Virtanen, Seija (Helsingin yliopisto, 2015)
    Acid loading from cultivated acid sulphate soils (AS) deteriorates the quality of the recipient waters, especially on the coast of the Gulf of Bothnia. These fields reclaimed in the past without knowing their deleterious consequences still cause long-lasting hazards. The aim of this thesis was to explore redox processes in AS soils in relation to their water management aiming at mitigation the water quality. Redox processes and the quality of pore and discharge water were investigated for 2 ½ years in waterlogged cropped and bare lysimeters as well as in effectively drained cropped lysimeters. This methodology has not been previously used in studies on boreal AS soils. In addition, the level and quality of groundwater was monitored for three years in an AS field. Physical properties of the soil were determined to unravel the ripening processes under different water management systems. The results obtained at the lysimeter and field scales were compared using the similarity approach, a new methodology in soil science. Upon waterlogging, the reduction-induced elevation of pH immobilized Al but concomitantly increased the Fe2+ concentration in pore and discharge water. This reaction pattern maintained the acidity of discharge water. This finding contrasts with the results obtained in warmer environments. The main reasons for the discrepancy were: 1) acidic conditions favour iron reducers before sulphate reducers, 2) the AS soils rich in poorly ordered Fe oxides, 3) low temperature, 4) freshwater used in waterlogging and 5) low labile organic matter in horizons poor in root material. However, intensified drainage caused the oxidation of sulphidic material in subsoils. The oxidation proceeded rapidly, although the most reactive sulphides constituted only 1% of the total sulphides. Ripening processes enhanced the oxidation of sulphides by promoting the diffusion/convection of oxygen and nitrate into the sulphidic horizon. The findings suggest that nitrate may also oxidize sulphides in boreal AS soils. These results highlight the importance of preventing soil ripening in order to keep sulphidic horizons waterlogged and impermeable. The findings reveal that to mitigate environmental hazards it is not rational to waterlog cultivated boreal AS fields close to the plough layer. Otherwise there is a risk that Fe2+ will leach to watercourses, where it will cause acidity as well as oxygen depletion as a result of oxidation and hydrolysis. The study revealed that the acidity retained in the form of secondary minerals retards neutralization and thus counteracts the mitigation measures. Waterlogging of only the transition and sulphidic horizons appears to be the most efficient water management option to improve discharge water quality. This practice can especially be recommended on the coast of the Gulf of Bothnia, where AS soils are abundant in reactive sulphides and may oxidized by nitrate, leading also to increased nitrous oxide emissions.
  • Hovi, Aarne (Helsingin yliopisto, 2015)
    This thesis presents basic research on how airborne LiDAR measurements of forest vegetation are influenced by the interplay of the geometric-optical properties of vegetation, sensor function and acquisition settings. Within the work, examining the potential of waveform (WF) recording sensors was of particular interest. Study I focused upon discrete return LiDAR measurements of understory trees. It showed that transmission losses influenced the intensity of observations and echo triggering probabilities, and also skewed the distribution of echoes towards those triggered by highly reflective or dense targets. The intensity data were of low value for species identification, but the abundance of understory trees could be predicted based on echo height distributions. In study II, a method of close-range terrestrial photogrammetry was developed. Images were shown as being useful for visualizations and even the geometric quality control of LiDAR data. The strength of backscattering was shown to correlate with the projected area extracted from the images. In study III, a LiDAR simulation model was developed and validated against real measurements. The model was able to be used for sensitivity analyses to illustrate how plant structure or different pulse properties influence the WF data. Both simulated and real data showed that WF data were able to capture small-scale variations in the structural and optical properties of juvenile forest vegetation. Study IV illustrated the potential of WF data in the species classification of larger trees. The WF features that separated tree species were also dependent on other variables such as tree size and phenology. Inherent between-tree differences in structure were quantified and the effects of pulse density on the features were examined. Overall, the thesis provides basic findings on how LiDAR pulses interact with forest vegetation, and serves to link theory with real observations. The results contribute to an improved understanding of LiDAR measurements and their limitations, and thus provide support for further improvements in both data interpretation methods and specific sensor design.
  • Saarela, Svetlana (Helsingin yliopisto, 2015)
    Over the past decades it has been shown that remotely sensed auxiliary data have a potential to increase the precision of key estimators in sample-based forest surveys. This thesis was motivated by the increasing availability of remotely sensed data, and the objectives were to investigate how this type of auxiliary data can be used for improving both the design and the estimators in sample-based surveys. Two different modes of inference were studied: model-based inference and design-based inference. Empirical data for the studies were acquired from a boreal forest area in the Kuortane region of western Finland. The data comprised a combination of auxiliary information derived from airborne LiDAR and Landsat data, and field sample plot data collected using a modification of the 10th Finnish National Forest Inventory. The studied forest attribute was growing stock volume. In Paper I, remotely sensed data were applied at the design stage, using a newly developed design which spreads the sample efficiently in the space of auxiliary data. The analysis was carried out through Monte Carlo sampling simulation using a simulated population developed by way of a copula technique utilizing empirical data from Kuortane. The results of the study showed that the new design resulted in a higher precision when compared to a traditional design where the samples were spread only in the space of geographical data. In Paper II, remotely sensed auxiliary data were applied in connection with model-assisted estimation. The auxiliary data were used mainly in the estimation stage, but also in the design stage through probability-proportional-to-size sampling utilizing Landsat data. The results showed that LiDAR auxiliary data considerably improved the precision compared to estimation based only on field samples. Additionally, in spite of their low correlation with growing stock volume, adding Landsat data as auxiliary data further improved the precision of the estimators. In Paper III, the focus was set on model-based inference and the influence of the use of different models on the precision of estimators. For this study, a second simulated population was developed utilizing the empirical data, including only non-zero growing stock volume observations. The results revealed that the choice of model form in model-based inference had minor to moderate effects on the precision of the estimators. Furthermore, as expected, it was found that model-based prediction and model-assisted estimation performed almost equally well. In Paper IV, the precision of model-based prediction and model-assisted estimation was compared in a case where field and remotely sensed data were geographically mismatched. The same simulated population as used in Paper III was employed in this study. The results showed that the precision in most cases decreased considerably, and more so when LiDAR auxiliary data were applied, compared to when Landsat auxiliary data were used. As for the choice of inferential framework, it was revealed that model-based inference in this case had some advantages compared to design-based inference through model-assisted estimators. The results of this thesis are important for the development of forest inventories to meet the requirements which stem from an increasing number of international commitments and agreements related to forests. Keywords: design-based, Landsat, LiDAR, model-based, multivariate probability distribution, sampling.