Faculty of Agriculture and Forestry

 

Recent Submissions

  • Greis, Maija (Helsingin yliopisto, 2023)
    The present study concentrates on the prospects of texture perception and consumer acceptance of plant-based (PB) yogurts. Temporal dominance of sensations (TDS) with consumers (N=87) was used to analyze the dynamic mouthfeel. Following TDS, overall and mouthfeel liking were evaluated using a 7-point hedonic scale. Some PB yogurts were found to be similar by their mouthfeel profile and equally liked as dairy yogurts. Physicochemical properties of the yogurts were also analyzed. Significant differences in flow behavior and small deformation rheology were found between them. Among PB yogurts, thick, creamy, thin, and watery mouthfeel sensations were strongly associated with steady shear rates and apparent viscosity. Large deformation rheology proved to be a useful tool to study PB yogurts. The role of selected factors on mouthfeel perception was studied. Generic descriptive analysis (GDA) and TDS with a trained panel were conducted to study the influence of aroma compounds possibly congruent with sweetness perception (N=10 panelists × 4 sessions). Unflavored and flavored (vanilla; 0.05%; 0.1%; lemon: 0.025%; 0.05%) samples were included. The aromas modified the perceived sweetness in PB yogurts; however, aroma and perceived sweetness did not impact the mouthfeel. The role of product information, visual experience, and cross-cultural differences in mouthfeel perception and consumer acceptance were studied with two identical consumer studies: in the US (n=101) and in Finland (n=96). Six blueberry-flavored yogurts were blended in varying plant-to-dairy proportions. Selected texture-related attributes were studied first by appearance and, after tasting, by mouthfeel using the Rate-all-that-apply (RATA) and Just-about-right (JAR) methods. The results showed that product information did not have an impact on the texture perception. The interpretation of mouthfeel descriptors such as creamy can vary depending on the culture, language and the yogurt market. Texture descriptors were emphasized differently by visual experience and mouthfeel, depending on sample and texture characteristics. In overall acceptance, clear differences were found between the samples: PB-labeled samples with a higher dairy content were most liked, but there were no differences between the countries. Interestingly, the PB-labeled yogurt (50:50) was more liked compared to the same yogurt labeled as dairy yogurt, indicating that consumers have different expectations toward PB and dairy yogurts. Creamy was found to be the main driver of liking among the PB-labeled yogurts in the US and in Finland. The present work lays a cornerstone for the dynamic texture profile and physicochemical properties of PB yogurts in relation to dairy yogurts. The current study contributes to the understanding of the basis of the texture and mouthfeel of PB yogurts. While this thesis focuses on PB yogurts with oat as the main plant ingredient, the results will benefit product development and research on other types of PB yogurts, as well as providing insight to the sensory and physicochemical methods suitable for studying food texture and structure with semisolids. Future studies should focus on the effect of different food ingredients on the texture of PB yogurts, as well as on the preferences of segments of the consumer population.
  • Tang, Yu (Helsingin yliopisto, 2023)
    Stable carbon isotope composition (δ13C) in trees responds sensitively to the changing environmental conditions and thus provides a powerful tool for paleoenvironmental reconstructions. The retrospective interpretation of tree δ13C signal depends on comprehensive understanding of how environmental and physiological signals are recorded in δ13C during photosynthesis and how the δ13C signal is modified after photosynthesis. This thesis aims to improve the understanding of photosynthetic and post-photosynthetic isotope fractionation processes, and to examine the suitability of tree-ring δ13C for intra-seasonal reconstructions of intrinsic water use efficiency (iWUE). The former goal was studied by combining compound-specific isotope analysis of organic matter with isotope discrimination models and online δ13C measurements of leaf CO2 fluxes for field-grown mature Scots pine (Pinus sylvestris L.). The latter was achieved via comparing 18-year-long intra-seasonal iWUE chronologies estimated from laser ablation derived tree-ring δ13C, gas exchange and eddy covariance data. Mesophyll conductance and time-integral effect of leaf assimilates had a clear impact on the intra-seasonal dynamics of leaf sugar δ13C. No significant use of reserves was observed for biomass growth of needles, stem or roots of Scots pine. Unlike sucrose, leaf bulk matters had significant δ13C offsets from new assimilates, leading to distorted environmental and physiological signals documented in their δ13C. The reliability of tree-ring δ13C data for intra-seasonal iWUE reconstructions was supported by an agreement of intra-seasonal patterns across the iWUE estimation methods. These results broaden our knowledge of the less well-known photosynthetic and post-photosynthetic isotopic fractionation processes, demonstrate the benefits of analysing sucrose δ13C for understanding plant physiological responses, and show that the tree-ring δ13C-based iWUE reconstructions can be extended to intra-seasonal scale. This information not only helps to better unravel δ13C signal in trees, but also improves reliable reconstructions of environmental and physiological signals from tree-ring δ13C.
  • Puustinen, Markku (Helsingin yliopisto, 2023)
    Abstract From natural areas, the so-called natural leaching consists of volume and concentrations of runoff waters, the latter determined by the natural prop-erties of the area. By draining the land, the water circulation of the area converted to agricultural use speeds up, which affects the quality of the runoff water. The natural material flow, which has changed as a result of the conversion, now forms the basic load level of arable farming on the scale of the drained area. Cultivation practices and methods change this basic level in the annual cycle of cultivation, and the effects extend to downstream water bodies via the drainage and riverbed networks. In this work, a runoff water management model for agricultural areas, the VIHMA tool, was developed. The VIHMA model is intended for the planning and impact assessments of water conservation measures imple-mented in- and outside of arable fields. The basis for the calculation of the load assessment is formed by the specific load coefficients that predict the annual loads of solid matter, nitrogen (N) and phosphorus (P). These coef-ficients are derived from the data collected in Finnish experimental fields. The coeffi-cients cover, by slope class and soil type group, the usual tillage and plant cover options that affect the winter state of the fields in the annual cycle of cultivation. The predicted values of the effects of field-block specific water protection measures are based on changes in cultivation and tillage prac-tices. In other words, on the differences in the specific load factors in the tool with and without measures. Based on Finnish studies, the tool also includes impact figures of buffer zones and wetlands, which are comparable to those of block-specific water protection measures. The VIHMA tool is used to evaluate the long-term average annual loads of solid matter and nutrients caused by farming practices in the examined catchments in two stages. Firstly, the average load without agri-environmental measures and secondly, the total effects of the simulated agri-environmental measures. As applied for the entire arable area of Fin-land, VIHMA's estimates of the annual loads of solid matter and nutrients corresponded to the specific loads of the small catchments of the Finnish agricultural monitoring network. Similarly, when applied in a single catchment, VIHMA's load estimates correspond to the long-term monitor-ing results of the same area. In VIHMA's assessments of agri-environmental measures, the effects of direct sowing were evaluated as a method to replace autumn ploughing. The overall load-reducing effects of gradual implementation of direct sowing, starting from the most sloping fields, were considerably large for both solid matter and nutrients. The ex-ception was a significant increase in leaching of soluble P. In VIHMA's as-sessment, decreasing the P-status of fields from the highest P-concentration categories to average concentration levels was an effective measure to decrease the risk of soluble P leaching. In the development work of the VIHMA tool, the focus was on the com-prehensive integration of different viewpoints, scales, load processes and influencing factors. The tool covers solid matter and nutrient loads’ phe-nomena related to field cultivation and different hydrological years as av-erage long-term estimates. Technically, the tool functions as an Excel-based calculation application, where the input data are distributions de-scribing i) the characteristics of the fields in the area under consideration, ii) basic information on cultivation and iii) implemented or planned envi-ronmental measures. The application of the tool in the planning of water protection measures makes the characteristic features and farming practic-es of the target area transparent and the impact comparisons of alternative measures become the basis for the selection and targeting of measures. The VIHMA tool is applied as it is in different target areas without separate calibration. VIHMA’s use just requires input data describing the area's characteristics and farming practices. Keywords: erosion, nutrient load, particulate phosphorus, soluble phos-phorus, nitrogen, load control, buffer zone, water protection wetland, field measures
  • Rajewicz, Paulina (Helsingin yliopisto, 2022)
    Boreal forests assimilate a substantial fraction of global atmospheric CO2 and thus play a key role in the global carbon cycle. However, due to the prevalence of evergreen species, monitoring photosynthetic dynamics of boreal forests is challenging when using conventional greenness- or vegetation-indices. Fortunately, an increasing body of evidence suggests that chlorophyll-a fluorescence (ChlF) – a weak red-to-far-red radiation emitted by the chlorophyll a molecules nanoseconds after light absorption – can enhance our capacity to assess photosynthetic dynamics in evergreen-dominated ecosystems. However, before extracting complete information embedded in the ChlF, comprehensive understanding and quantitative characterization of the mechanisms that connect the measured ChlF to photosynthesis across various scales are essential. In this thesis, I discuss several challenges that we currently need to face to leverage the full potential of ChlF. I present a roadmap through these challenges, towards a more comprehensive interpretation of ChlF. The main focus is laid on the challenges concerning ChlF measured at a leaf-level in methodological and mechanistic contexts. In other words, this thesis contributes to the interpretation of ChlF by contextualizing the influence that methodological and mechanistic factors have on leaf-level spectral ChlF. An impact of methodological factors, measuring geometry and sample arrangements, on spectral ChlF was analysed. Results indicate that ChlF shape is less dependent on measuring geometry as compared to ChlF magnitude and that if needle-mats are used, measuring geometry does not lower the comparability between studies using different setups. Mechanical factors were investigated in terms of their effect on spatial and temporal variation in spectral ChlF. The diversity of species and light environments within an ecosystem was shown to generate a temporarily-invariant, baseline variation in leaf spectral ChlF, as well as contrasting seasonal photosynthetic acclimation patterns. Consequently, I suggest the need for considering both the methodological and mechanistic contexts in the interpretation of ChlF.
  • Niemi, Mikko (Helsingin yliopisto, 2023)
    In Finland, peatland forests are significant for wood supply, although simultaneously, they are also important for biodiversity, carbon sequestration, water conservation, and recreation. In the 1960s and 1970s, peatland forests in Finland were extensively drained to increase tree growth and fulfil the needs of the forest sector. However, this extensive drainage has negatively impacted on the biodiversity of peatland ecosystems, and substantially increased nutrient and sediment emissions to lakes and rivers resulting in eutrophication, turbidity, and brownification of these water bodies. This dissertation presents a number of approaches to move peatland forest management in a more environmentally sound direction, which may increase the general acceptability of peatland forestry. Airborne LiDAR (Light detection and ranging, i.e., laser scanning) derived 3D point cloud provides useful data, for example, to estimate forest biomass, to identify lowproductive peatland forests, to model overland water flows, and to identify wet areas. The strength of airborne LiDAR is the ability of laser pulses to pass through tree canopies and obtain accurate observations from the ground level. The information derived from airborne LiDAR can enhance the planning of peatland forest management, as much of the planning can be done remotely, and supplementary field work can be implemented in areas of strategic need. This study presented the novel idea of applying local binary patterns for the prediction of terrain trafficability, which should be considered in further studies and practice. The moisture index derived from the local neighborhood can reveal the small-scale variations in terrain moisture. This study also presented the novel idea to create spatial models to identify suitable locations for water protection structures, which may help forest managers to plan water protection of ditch network maintenance or peatland restoration operations. Overall, the utilization of airborne LiDAR-derived information for the development of peatland forestry practices shows great potential.
  • Törmänen, Tiina (Helsingin yliopisto, 2022)
    Sustainable forest management practices are crucial for minimizing environmental impacts, and to keep forests and the underlying soils healthy to maintain productivity, and to improve adaptability to climate change and mitigate it in the long-term. There, carbon and nitrogen cycling play crucial roles in proper functioning of forest ecosystems. The overall aim of this thesis was to explore the effects of logging residues on the early-stage dynamics of the main nitrogen and carbon cycling processes in upland forest soils after final felling. A specific aim was to compare the effects of logging residue piles consisting of different tree species, i.e., Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), and silver birch (Betula pendula Roth.). A special attention was given to the response of soil to different amounts of residues. The effect of logging residues on soil chemical properties and processes was stronger in the organic layer than in the mineral soil layer. Logging residue piles stimulated carbon and nitrogen cycling, especially net nitrification within the first year after the residue treatment. Subsequently, nitrogen was lost via leaching as nitrate and gaseous emission as nitrous oxide. Nitrous oxide fluxes were generally low, although higher in the plots containing logging residues. Spruce residues tended to stimulate nitrous oxide emissions for longer than the residues of the other tree species. Depending on the tree species, nitrous oxide production originated from both autotrophic nitrification and denitrification. Nitrogen concentrations in the soil percolate water already accelerated one year after the establishment of the residue piles. Logging residues increased nitrate and ammonium concentrations, which were highest under birch residues. The effect of logging residue piles on soil was stronger when compared to milder tree species effects. Biological nitrogen fixation activity tended to be higher in branches than in needles or leaves, and higher in coniferous residues. The results of this study raise the importance of more even distribution of logging residues on the forest floor instead of piling them to avoid harmful environmental effects and to maintain soil nutrient balance. The ability of soils to retain nitrogen needs additional attention in forest management practices, especially in boreal areas where nitrogen limits the growth of forests.
  • Resler, Megan (Helsingin yliopisto, 2022)
    Driven by a growth and profit maximization mindset, the corporate food regime has contributed to wide-spread food insecurity, chronic and acute hunger, soil, water, and ecosystem degradation, rapid loss of biodiversity, and a global de-skilling of populations. To re-direct this crisis-bound trajectory, sustainable food system transformation is necessary and urgent. In recent years, the science, practice and social movement of agroecology has gained increasing political and social momentum as an alternative paradigm to the corporate food regime, and as a solution to many cross-cutting socio-cultural and ecological crises. Despite scholarly roots in primarily rural agroecosystems, emerging agroecology research has begun to explore the role(s) agroecology principles and practices can play in urban contexts, which require new spatial perspectives through which to imagine and implement change. Among others, municipally-embedded social infrastructure–that is, the physical conditions shaping, enabling, and constraining, how people interact in urban publics–stands to play a key role in bringing agroecology to scale in the city. The overarching objective of this interdisciplinary thesis is to investigate social infrastructure as an entry-point for scaling urban agroecology. The thesis itself consists of an introductory chapter and three original articles, each framed by a unique agroecology scaling pathway and applied to an illustrative social infrastructure case. Using thematic analysis of qualitative data with community gardeners and regional food policy documents in the case of Seattle, U.S.A, I identify two points of intervention for scaling-up (impacting laws and policy) agroecology in the city: improved deliberative processes across power hierarchies and opportunities for strengthening self-efficacy (Article I). These findings offer a conceptual and empirical contribution to the ongoing conceptualization of agroecological urbanism emerging from the disciplines of agroecology and urban studies. Similarly, through a thematic analysis of qualitative data with allotment gardeners–though, here, integrated with a crisp-set qualitative comparative analysis of name generator materials–I investigate the spatiality of social capital formed among allotment gardeners in the urban allotment gardens of Vantaa, Finland (Article III). The study finds that though boundary-crossing contacts are formed within the social infrastructure, they evidence little potential for ‘scaling resource transfers’ across socially-distant groups. Further, without facilitated inter-cultural dialogue, they evidence the potential for these spaces to foster inter-group tension and reproduce social challenges. To scale-deep urban agroecology (impact hearts and minds), an argument for municipal investment in transformative learning within existing communities of practice is made. Lastly, I zoom out to examine social infrastructure at the network level, putting forth an urban planning tool to assess the distribution of urban greenspace diversity across a municipality (Article II). I apply the tool to the socio-spatially polarizing case of Vantaa, Finland, and find that the distribution of urban greenspace diversity is not currently correlated with the income, age structure, or proportion of residents with a foreign-background in the municipality. To scale-out agroecology (impacting distribution), we argue for the urgent need for current urban greenspace planning practice to move beyond ‘equal access’ urban greenspace planning, and work to integrate indicators that can account for the equitable distribution of environmental risks, impacts, and benefits–including, diverse social infrastructure for agroecology communities of practice. As a whole, this interdisciplinary thesis offers a package of empirical, methodological, and practical contributions to the fields of urban political agroecology, urban planning, and critical geography. While previous empirical urban agroecology research has focused on what types of transitions are needed, and how to enable their implementation, this thesis offers the novel spatial contribution of focusing on where agroecology transitions can scale from in the city-region. The thesis identifies social infrastructure as a key entry-point for urban agroecology transitions working to disrupt the food-disabling modes of the corporate food regime. The empirical baselines established in these studies are a first, necessary, step; applied research and interventions supporting the imagined food futures of civil society actors must follow.
  • Koponen, Sami (Helsingin yliopisto, 2022)
    This dissertation explores the artification of upmarket dining from the perspective of practice theory. Regarding the concept of artification, the study draws on theorisations in the field of aesthetics. Accordingly, it aims to elucidate how the practice of upmarket dining has adopted ways of thinking and acting conventionally associated with the societal domain of modern high art. Concerning practice theory, the study leans on the Schatzkian approach as frequently applied in empirical research on consumption since the early 2000s. The study investigates the artification of upmarket dining in the 2010s in Helsinki, Finland. It aims to elucidate how a more artful mode of dining out has been recently performed as interlinked components of a practice, that is, as materials, practical and general understandings, and ‘teleoaffectivity’. Based on the analysis of these performances and sociological literature on taste, the thesis also aims to provide the more artful mode of dining out with a specific definition. Additionally, the study responds to the question of whether the more artful mode of upmarket dining can be conceptualised as an integrative practice of artful dining. The empirical data consist of media representations of dining out, interviews with diners and restaurant professionals, and participant observation at different types of restaurants and gastronomic events. The data analysis drew on the practice-theoretical notion of practices as consisting of components. The results indicate that performances of a more artful mode of dining out draw on the principles of aesthetic novelty, nonconformity and complexity, the importance of which have been underlined in sociological studies on contemporary taste hierarchies. The results also show that the more artful mode of dining out can be conceptually understood as an integrative practice of artful dining. The difference between conventional upmarket dining, or fine dining, and the practice of artful dining more generally reflects the subtle and distinctive difference between aesthetic and artistic aesthetic (non-art) practices. The emergence of artful dining illustrates the diversification of dining out and upmarket dining. Relatedly, the study suggests that sociologists of consumption focusing on practice theory and dining out could fruitfully grasp the current variety in practices of dining out and upmarket dining through dividing these practices into smaller practice-entities. Lastly, the study looks beyond the restaurant world and calls for critical sociological debate on the role and nature of the aesthetic in late modern food culture.
  • Ryhti, Kira (Helsingin yliopisto, 2022)
    Boreal forest soils are globally one of the most extensive carbon storages, whereas soil respiration (carbon dioxide; CO2 efflux) forms the largest carbon flux from the ecosystem to the atmosphere. Current changes in the world climate may have unpredictable effects on belowground carbon processes, and thereby, on the carbon balance of boreal forests. To better understand the various processes in soil and to quantify the potential changes in the carbon cycle, forest-floor respiration was partitioned into five different components, and tree-root respiration was estimated, using four different methods in a mature boreal Scots pine (Pinus sylvestris L.) stand in southern Finland. Non-structural carbohydrate (NSC) concentrations in tree roots were determined, and carbon allocation to belowground by trees was estimated with the whole-tree carbon model ‘CASSIA’. In addition, tree-root respiration and heterotrophic soil respiration were separated using root exclusion in seven coniferous forests along a latitudinal gradient in Northern and Central Europe. The tree-root respiration comprised almost half of the forest-floor respiration, the heterotrophic soil respiration almost a third, and ground vegetation and respiration of mycorrhizal hyphae the remaining fifth in the boreal Scots pine stand. While the annual tree-root respiration decreased throughout the first three study years, the heterotrophic soil respiration increased when the mycorrhizal roots were excluded from the treatments. The tree-root respiration and most of the NSC concentrations were higher in the warmer years and lower in the cooler, as estimated with most of the methods. Three methods resulted in rather similar tree-root respiration estimations, while the tree-root respiration estimated with root incubation was significantly lower. The tree-root respiration was over 50% of the annual photosynthesis in the northernmost forest stand, whereas in the southernmost stand it was only up to 15%. Carbon allocation to the belowground, as modelled with CASSIA was a third of the annual photosynthesis on average and almost 5% for the symbiotic mycorrhizae.
  • Kyttä, Venla (Helsingin yliopisto, 2022)
    Due to many serious environmental issues, the production, consumption and disposal of biological resources must shift from a linear system towards a circular bioeconomy. Although the circular bioeconomy has the potential to respond to the changes needed in society, the environmental impacts of various practices must be assessed to identify potential challenges, such as land use competition with food production or negative environmental impacts. Agriculture is a particularly important multifunctional system for the circular economy, which, in addition to its primary function of food production, produces a variety of biomasses that can be utilized as raw material. Furthermore, agricultural systems can recycle by-products and wastes from other industries as fertilizers and soil improvers. The established method for calculating environmental impacts is the life cycle assessment (LCA) of a product, which aims to capture all impacts caused throughout the entire life cycle of a product system. An allocation procedure is used to partition the environmental impacts of multifunctional systems producing more than one product among all products, resulting in the environmental impact of a single product. This information on the environmental impacts of individual products is typically compared with the impacts of other similar products and used to support decision making. As the allocation method unavoidably affects the results for an individual product, the principles of the allocation methodology must be justified. This dissertation handles the methodological consideration of the circular bioeconomy in the context of LCA of products from agricultural systems. The objectives of the dissertation are to examine the multifunctionality of agriculture, the different by-products and their recycling, and how the choice of allocation method between products affects the results. Dairy production is used as an example case, since it produces two different foodstuffs as well as various inedible materials, making it an excellent research subject for dealing with multifunctionality. This dissertation consists of three research papers and a synthesis of them. The first paper (I) examines how the multifunctionality of livestock systems has been addressed in previous LCA studies through an extensive systematic review of 232 studies. The methodological treatment of recycling and the effect of the choice of method on the results are investigated in paper II through an LCA of recycled fertilizers. The third paper (III) compares the environmental impacts of beef from dairy and beef cattle, pork, cellular meat and tofu production at the system level instead of the level of individual products, considering all the inedible by-products. The findings of this dissertation demonstrate that, despite attempts to harmonize the LCA method, practices vary between studies and the differences in results due to the choice of method are significant. The relative system-level results also differ significantly from the allocated results for individual products. Hence, allocation should be avoided more often, and comparisons should be made between systems rather than individual products. This would also better reflect the reality, where decision making based on one product inevitably also affects all the other products produced by the system. For example, the environmental impact of milk and beef is usually dealt with separately, even though in reality milk cannot be produced without meat, and decision making on milk alone is not therefore possible. Hence, more system level research is needed.
  • Liu, Fengyuan (Helsingin yliopisto, 2022)
    Folate is essential for human health, playing a vital role in the metabolism of nucleic and amino acids. However, folate intake is below the recommendation in many countries. Mandatory folic acid fortification is practised in more than 80 countries around the world, but not, for example, in most EU countries. Additionally, there are concerns about excessive folic acid intake. Therefore, studying folate from natural sources, such as cereal and legume-based foods, is important. Unlike enriched folic acid, natural folates need to be liberated from the food matrix, and, further, most of them are unstable and can be lost during digestion. Thus, to understand the role of a food as a folate source, it is necessary to consider the bioaccessibility of folate, meaning the proportion of folate potentially available for absorption. However, knowledge about folate bioaccessibility in foods is still limited, especially at the vitamer level. Furthermore, the mechanisms behind how food matrices influence folate bioaccessibility are not well understood. This thesis aimed to investigate the bioaccessibility of endogenous folate in cereals and legumes. Folate bioaccessibility in cereal and legume matrices (flours, pastes and breads) was compared first. Next, the stability of folate vitamers during in vitro digestion was studied. Then, the effects of ingredients and processing methods on folate bioaccessibility were investigated. Finally, the significance of 5-methyltetrahydrofolate to folate bioaccessibility was examined. Samples were subjected to a static in vitro digestion model, and folates were analysed using ultra-high-performance liquid chromatography (UHPLC) coupled with photodiode array and fluorescence detection. Folate bioaccessibility in cereal and legume matrices ranged from 31% to 123%. Faba bean matrices generally had better folate bioaccessibility than cereal matrices. Among the breads, rye breads typically had higher folate bioaccessibility, and oat breads had lower folate bioaccessibility than the other breads. Three common trends in folate stability during in vitro digestion were found: (1) high stability of formyl pool folates, but frequent interconversion among formyl folates (10-formyldihydrofolate, 5-formyltetrahydrofolate) and 5,10-methenyltetrahydrofolate; (2) the decrease of reduced folates (tetrahydrofolate, 5-methyltetrahydrofolate, and 5-formyltetrahydrofolate); and (3) high stability of oxidised folates (folic acid and 10-formylfolic acid). These changes were universal for all studied food matrices, but the degree varied. 5-methyltetrahydrofolate was more stable in legume matrices than in cereal matrices. Both the ingredients and the processing methods affected the bioaccessibility of folate. Because of a larger formyl folate pool, whole-grain wheat bread had better folate bioaccessibility than white wheat bread. The inclusion of faba bean flour as a baking ingredient not only introduced a large formyl pool but also stabilised 5-methyltetrahydrofolate during digestion, improving both the folate content and bioaccessibility in bread. Folate bioaccessibility was easily improved with a simple paste making process. Conversely, baking with added yeast significantly enhanced the 5-methyltetrahydrofolate level in breads but decreased their folate bioaccessibility due to the instability of 5-methyltetrahydrofolate. Further experiments showed that 5-methyltetrahydrofolate was crucial for folate bioaccessibility and its stability in food matrices during the in vitro digestion was a trade-off between the pro-oxidative and protective factors. However, phenolic compounds could act as protective factors in stabilising 5-methyltetrahydrofolate. In summary, folates underwent significant changes during digestion. However, food matrices can be modified to turn these changes towards better folate bioaccessibility. Faba bean was shown to be a promising dietary source of folate. In addition to folate content, bioaccessibility should be considered when evaluating foods as folate sources.
  • Wen, Zilan (Helsingin yliopisto, 2022)
    In the boreal forest of Finland, spruce and pine form the basis for one of the largest industries contributing several billion euros in net export income yearly. However, a considerable proportion of the trees harvested are rotted and commercially less valuable largely caused by a species complex Heterobasidion annosum sensu lato (s.l.). The basidiomycete fungus H. parviporum threatens the health of boreal forest, especially Picea abies (L.) Karst (Norway spruce), by causing root and stem rot disease as comprehensively documented in our review article. We carried out a series of studies on the tree-fungal pathogen interactions, interspecific fungal interactions, and plant-endophyte-fungal pathogen interactions to identify vital traits or factors important for disease development and plant defense responses. The availability of genome sequences of both H. parviporum and Norway spruce enabled the identification of small secreted proteins of the necrotrophic pathogen (HpSSPs) and plant defense-related genes in H. parviporum-Norway spruce interaction. In my first study, I investigated the functional role of HpSSP as pathogenicity factor. A hypothetical protein HpSSP35.8, a homolog of HaSSP30 from H. annosum, with necrosis-inducing activity in Nicotiana benthamiana was evaluated. Interestingly, not all homologs of cell death-inducing HaSSPs could trigger cell death in Nicotiana leaves. Hsr203J and HIN1, which are useful makers for hypersensitive response (HR) cell death, were found to be activated in the non-host N. benthamiana by HpSSP35.8 infiltration. The activation of Hsr203J and HIN1 revealed a form of SSP-associated HR triggered by HpSSP35.8. WRKY12, ethylene response factor (ERF1α) and a chitinase gene PR4, endochitinase.B, PI1 and NPR1 were induced in HpSSP35.8-infiltrated leaves, revealing their roles in defense response probably related to JA/ET-mediated signaling pathway. HpSSP35.8 coding gene was highly expressed in the pre-symptomatic phase of host infection. This suggests that HpSSP35.8 probably had an important role during fungal penetration and colonization. The defense-related genes in seedling roots induced by the pathogen infection were ERF1a and ERF1b, WRKY12, LURP1, PR1, PAL, which demonstrated that the phenylpropanoid pathway and the JA/ET-signaling pathway were activated in response to the pathogen. In a follow-up study, I conducted a detailed analysis of H. parviporum effectome. H. parviporum was predicted to have nearly 300 small secreted proteins or effector candidates based on some of the characteristic features including secretion, expression in planta, cysteine and small protein size. The transcriptome profile analysis during fungal development and saprotrophic or necrotrophic growth showed that various HpSSPs were significantly induced during infection of woody trees, including HpSSP35.8. About a dozen small secreted proteins of H. parviporum were further selected to analyze their expression dynamics during interspecific fungal interaction with the endophyte Phialocephala sphaeroides and other fungi. Some HpSSP-coding gene expression varied according to the confronted fungus and the stage of interaction, and some others shared a common trend in expression over different interactions and stages. The formation of barrage zone and antagonism at distance during interspecific interaction indicated a combative and antagonistic impact. Some fungal species, which were overgrown by H. parviporum, had no inhibitory effect on the pathogen growth. Moreover, the expression of HpSSP-coding genes in the interaction with antagonism at distance was not as active as those in the interaction with barrage zone or overgrowth. In paper III, it was observed that although the dark septate endophyte Phialocephala sphaeroides had no obvious in vitro antagonistic effect on the pathogen H. parviporum growth, it was found to promote the root development of Norway spruce seedlings. Co-infection was set up to investigate the effect of the host interaction with the endophyte and the pathogen H. parviporum on Norway spruce defense responses and fungal transcriptomic responses. RNA-seq analysis revealed that a large percentage of reads were undoubtedly mapped to Norway spruce, and a small part of reads were mapped to fungi. Phenylpropanoid biosynthesis was generally activated in Norway spruce seedlings in response to the endophyte inoculation (PaPs), pathogen infection (PaHp), and co-infection (PaPsHp), but the expression patterns of phenylpropanoid-related genes varied among different inoculations. Many gene members of PALs and peroxidase genes (POXs) were upregulated in PaPs, while not expressed in PaPsHp. This suggests that the subsequent infection with the pathogen was able to influence the phenylpropanoid metabolism modulated by the endophyte. Flavonoid biosynthesis pathway was also activated during fungal infection, with only 6 genes encoding enzymes related to CHI, F3’5’H, DFR, and ANR upregulated under a certain condition and 14 genes downregulated in PaHp, PaPs, PaPsHp. Multiple genes were uniquely upregulated in PaPs, which involved jasmonic acid (JA) signaling pathway, plant hormone signal transduction, MAPK signaling pathway and calcium-mediated signaling. It was concluded that the subsequent H. parviporum infection triggered reprogramming of host metabolism. Further analysis showed that the transcript abundance of H. parviporum reduced dramatically in the presence of the endophyte in the co-infection seedlings, compared to those in the pathogen inoculation. Although the endophyte lost the antagonistic effect against H. parviporum at mycelium level, it seems to have a suppressive effect on H. parviporum at transcript level. With a slight decrease in the transcript abundance of P. sphaeroides in co-infection, P. sphaeroides had a transcriptome shift from fungal growth to stress response in the presence of the pathogen H. parviporum. Surprisingly, the roots of the pathogen-inoculated seedlings developed better than control seedlings, indicating H. parviporum was able to weakly improve root growth. We found that both the endophyte and the pathogen had genes associated with hormone, polyketide and Iron-sulfur proteins, which might involve auxin-related pathways responsible for plant growth promotion. Moreover, the DSE P. sphaeroides could produce indolic compounds in culture filtrate, and the endophyte culture filtrate was shown to promote the development of Arabidopsis root hair.
  • Luoma, Ville (Helsingin yliopisto, 2022)
    Forests are dynamic ecosystems that are constantly changing. The most common natural reasons for change in forests are the growth and death of trees, as well as the damage occurring to them. Tree growth appears as an increment of its structural dimensions, such as stem diameter, height, and crown volume, which all affect the structure of a tree. Repeated measurements of tree characteristics enable observations of the respective increments indicating tree growth. According to current knowledge, the tree growth process follows the priority theory, where trees aim to achieve sufficient lightning conditions for the tree crown through primary growth, whereas increment in diameter results from the secondary growth. Tree growth is known to have an effect on the carbon sequestration potential of trees as well as on the quality of timber. To improve the understanding of the underlying cause–effect relations driving tree growth, methods to quantify structural changes in trees and forests are needed. The use of terrestrial laser scanning (TLS) has emerged during the recent decade as an effective tool to determine attributes of individual trees. However, the capacity of TLS point cloud-based methods to measure tree growth remains unexplored. This thesis aimed at developing new methods to measure tree growth in boreal forest conditions by utilizing two-date TLS point clouds. The point clouds were also used to investigate how trees allocate their growth and how the stem form of trees develops, to deepen the understanding of tree growth processes under different conditions and over the life cycle of a tree. The capability of the developed methods was examined during a five- to nine-year monitoring period with two separate datasets consisting of 1315 trees in total. Study I demonstrated the feasibility of TLS point clouds for measuring tree growth in boreal forests. In studies II and III, an automated point cloud-based method was further developed and tested for measuring tree growth. The used method could detect trees from two-date point clouds, with the detected trees representing 84.5% of total basal area. In general, statistically significant changes in the examined attributes, such as diameter at breast height, tree height, stem volume, and logwood volume, were detected during the monitoring periods. Tree growth and stem volume allocation seemed to be more similar for trees growing in similar structural conditions. The findings obtained in this thesis demonstrate the capabilities of repeatedly acquired TLS point clouds to be used for measuring the growth of trees and for characterizing the structural changes in forests. This thesis showed that TLS point cloud-based methods can be used for enhancing the knowledge of how trees allocate their growth, and thus help discover the underlying reasons for processes driving changes in forests, which could generate benefits for ecological or silvicultural applications where information on tree growth and forest structural changes is needed.
  • Järviö, Natasha (Helsingin yliopisto, 2022)
    Advancements in agriculture and increases in the human population have led to a surge in agricultural and aquacultural production. This increase in production has come at a cost. The consequences of current food production for the environment have never been so pronounced in human history, threatening the relatively stable state in which the Earth system has remained over the past 11,700 years of the Holocene epoch. Intensive farming systems often rely heavily on external inputs such as pesticides, herbicides and fertilizers to suppress the natural process of species diversification on the land, which lead to problems such as eutrophication, soil exhaustion and desertification. Other examples of environmental impacts resulting from current agricultural practices include deforestation and land degradation leading to the loss of valuable ecosystems and biodiversity, accelerated climate change, over-extraction of groundwater, terrestrial acidification, and biological crises such as the outbreak of COVID-19 pandemic. To reduce the environmental impacts of the food system, the search for more sustainable protein alternatives to replace animal-based proteins is one of the foremost research topics in food science and biotechnology today. Cellular agriculture — the production of agricultural products using cell-culturing technologies — is an approach that seeks to decouple food production from conventional agricultural farming, and, therefore, has the potential to decrease the environmental burden of food production. Cell-culturing technologies usually utilize bioreactors, creating closed production processes that allow for efficient recycling of inputs, and control of emissions from the production process. Another benefit of cell-cultured products is increased resilience of the food production system towards environmental changes, due to reduced reliance on conventional agricultural inputs. However, estimates of the environmental impacts of cell-cultured foods are still mostly lacking due to the novelty of these products. The aim of this dissertation is to improve the understanding of environmental impacts of protein-rich cellular agricultural products in comparison with those of existing protein-rich food and feed ingredients originating from agricultural and aquacultural systems. The environmental impacts of protein-rich cellular agricultural products were quantified to gain an understanding of the production processes contributing most to these impacts, and how these differ from agricultural and aquacultural products. Lastly, the work presented in this dissertation seeks to explore how the environmental impacts of cellular agricultural protein products can be reduced through alterations to their production processes. However, as GHG emissions resulting from aquacultural production in mangrove forests have been systematically excluded from environmental impacts assessments, a fair comparison between protein produced by cellular agriculture and aquaculture is compromised. The work in this dissertation, therefore, additionally focuses on the development and application of a method to quantify the GHG emissions caused by LULUC of mangrove forest. The protein-rich food and feed ingredients studied were microbial protein produced using hydrogen-oxidizing bacteria (HOB) (hereafter referred to as MP) and ovalbumin produced using the Trichodora reesei fungi (Tr-OVA). Shrimp was selected on the basis that aquaculture products are often underrepresented in environmental assessment studies in contrast to their importance as a protein source for many people(Gephart et al., 2021). MP and Tr-OVA are recently developed cellular agricultural products that can be used either as food or feed ingredients and are examples of cellular (MP) and acellular (Tr-OVA) products. To address the aims of the research, the life cycle assessment (LCA) method was used. LCA allows for the quantification of inputs and outputs at all production stages throughout a product’s life cycle and the coupling of these to various environmental impact categories, such as global warming potential (GWP), land use, and eutrophication. This enables a fair comparison between different protein-rich food and feed products originating from distinctly different systems. The environmental impacts of the three protein-rich products studied were also compared to the environmental impacts of other protein-rich products found in literature. GHG emissions caused by land use and land-use change (LULUC) of mangrove forests are often overlooked in LCA studies, despite the large contribution of LULUC emissions to climate change (approximately 13% of global emissions in the year 2015). Article I, consequently, focuses on the introduction of a method to include this specific emissions source and on applying it to a case study of shrimp farming in mangrove areas. Article II quantifies the environmental impacts of MP production. MP is a single-cell protein in the form of a flour-like powder with a 65% protein content. Because MP production uses autotrophic HOB there is no reliance on any agricultural inputs. Article III investigates the environmental impacts of Tr-OVA production. Like MO, Tr-OVA is a protein-rich powder produced in bioreactors through a closed process and has a 92% protein content. However, unlike MP, its production relies on glucose from agriculture. Using modern biotechnological tools, the gene carrying the blueprint for ovalbumin (SERPINB14) is inserted into the fungus, which then starts to produce the same protein — ovalbumin — that is normally found in chicken eggs. Cell-cultured ovalbumin can be used as a direct replacement for the chicken-based egg white that is widely used in food processing. The results of this dissertation showed great potential for MP and Tr-OVA to reduce the environmental impacts associated with protein production — especially when replacing protein from livestock sources — with the greatest reductions seen in land use and GWP compared to other protein-rich food and feed sources. The amount of land needed to produce MP and Tr-OVA was 0.1-1.3% of the land required for beef herds. Even by comparison to peas, which generally require little land compared to other animal and plant-based protein sources, land use requirements were 73-97% less. Both MP and Tr-OVA production also led to reductions in GWP when compared to other protein-rich foods, especially by comparison to animal-based protein sources. However, agricultural protein alternatives with a lower GWP were also identified, such as peas, rapeseed cake and soybean meal. Differences in the impacts of MP and Tr-OVA production were mostly explained by the reliance of Tr-OVA on agricultural inputs. Depending on the impact category, up to 94% of the environmental impacts of Tr-OVA production were related to its use of agriculturally sourced glucose. For MP, environmental impacts were mainly caused by the use of electricity; up to 90% depending on the category. For Tr-OVA, the impacts caused by the use of electricity were between 0% and 56%. The results for shrimp clearly indicated the importance of the inclusion of LULUC emissions from mangrove deforestation, as GHG emissions were 14-60 times higher for shrimp farming systems located in former mangrove areas than for systems that were not. The GHG emissions of shrimp produced in mangrove areas far outweighed the GWP of other protein-rich food sources and were 4.5 times higher than that of beef production from beef herds. Despite the great potential of cellular agriculture products to reduce the environmental impacts of protein production, minor trade-offs were found. For example, the potential for ozone depletion and water scarcity were higher for Tr-OVA in comparison to other feed protein alternatives. The environmental impacts of cellular agricultural products could be further reduced by using renewable or low-carbon energy sources. However, the electricity requirements for cellular agricultural products are higher than those of agriculture and aquaculture. As many sectors are looking to move away from fossil fuels towards low-carbon electricity sources, potential greater demand for electricity from the food sector will add further pressure to increase sustainable electricity production capacity. The work in this dissertation focused solely on the environmental impacts of food production. Additional research is needed into the role of cell-cultured food within a sustainable food system. This means that the research begun in this dissertation should be expanded to include other environmental impact categories such as biodiversity impacts, and the loss of ecosystem services. Additionally, there is a need to increase understanding of the social and economic implications of the introduction of cell-cultured foods, such as MP and Tr-OVA, into the food systems in different regions of the world.
  • Hu, Man (Helsingin yliopisto, 2022)
    An important challenge in forest management is how to predict tree/forest growth, biomass, and structural variables accurately and easily. Tree structural relationships between measurable tree dimensions and biomass components are therefore important because they provide a basis for further model use. In this context, exploring the age effect on structural relationships is consequential because it allows us to be able to understand the regularities of tree structure and growth and to utilize new measurement technologies such as terrestrial laser scanning (TLS) for estimating more detailed tree structure and biomass. Further, knowledge on the tree structure changes with age can act as a reference to provide support for better model use with respect to tree age. The main objectives of this study were 1) to test the age effect on tree structure and biomass allocation equations in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies [L.] Karst.) to understand the tree structural regularities with growth; 2) to further utilize the tree structural regularities to integrate with TLS data to improve the estimation of branch attributes in Scots pine by introducing a new method (TSM_tls); 3) to refine a process-based model PREBAS to be applicable on multiple-cohorts stands; and 4) to test the possibility of considering tree structure changes with age when applying the PREBAS model to estimate stand level biomasses. Multiple data sources included in this study were: destructive tree measurements, consecutive forest inventory data and TLS data. Results showed that tree structure variables vary a lot with growing age, as well as the biomass proportion of tree components (foliage, branch and stem). As trees mature, the tree structure is rather stable as biomass allocation and tree structural variables become steady. Moreover, in all age groups the pipe model theory (PMT) based tree equations suit well in both Scots pine and Norway spruce suggesting stable tree structure relationships with growing age. However, age dependence was detected on the slope parameters of all these equations, except for the branch-related equations in Scots pine and stem form coefficient below the crown base in both species. With age-specific parameters, the tree structural variables and biomass of each tree component can be estimated accurately. Among the tree structural equations, the ratio between cross-sectional area at the crown base and the total branch basal area was independent of tree age in Scots pine. Utilizing this constant relationship, the proposed TSM_tls method presented higher accuracy and lower error in estimating individual branch diameter and biomass in each canopy layer compared with the other TLS-based method, suggesting a fair performance of TSM_tls method. On stand level, the refined PREBAS model with DBH size classes showed a better estimation of tree variables and biomass in uneven-aged stands compared with the existing PREBAS version, although the bias of biomass estimation still existed. Moreover, the refined PREBAS model simulated the stand level mean tree structure more consistent with observations compared with existing PREBAS version. The mean tree biomass estimations using different approaches (age-specific biomass equations and PREBAS model) showed noticeable difference in both Scots pine and Norway spruce in most cases. Our results highlight the importance of tree structure relationships and demonstrate the possibility of better model use by accounting these relationships. Considering the limited sample trees of testing TSM_tls method, more data including different species and more sample trees should be collected to confirm our conclusion. Moreover, the results also suggest further PREBAS model calibration on uneven-aged stands is required with larger dataset including tree structure and biomass information.
  • Kellock, Miriam (Helsingin yliopisto, 2022)
    Physicochemical lignocellulose pretreatment and subsequent enzymatic conversion of polysaccharides to platform sugars is an important technology in the valorisation of various lignocellulosic biomass streams. This technology is needed in the bio- and circular economy. Lignin, one of the main components in lignocellulose, is known to inhibit enzymatic hydrolysis by non-productively binding enzymes and sterically preventing enzymes to access cellulose. In this work, the aim was to elucidate how lignin in herbaceous plants and softwood is modified during pretreatment and what is the effect of pretreatment severity on lignin-derived inhibition in the enzymatic hydrolysis. Characteristics of cellulases and hemicellulases contributing to binding and inactivation on lignin were investigated. Spruce and wheat straw were hydrothermally pretreated with or without an acid catalyst at increasing severities, followed by isolation of the lignin to explore the inhibitory effects. Lignin inhibition in the enzymatic hydrolysis of microcrystalline cellulose Avicel increased with increasing pretreatment severity. When spruce and wheat straw were pretreated at the same severity, as assessed by the combined severity factor, lignins from both biomasses were equally inhibitory. Furthermore, lignin from mild pretreatment severities did not have a significant effect on the hydrolysis of Avicel. This indicate that the changes in lignin structure during pretreatment are the main reasons for the inhibitory effect of lignin. A decrease in β-O-4 aryl ether bond as well as a change in molecular weight of lignin was observed after pretreatment. The molecular weight of spruce lignin decreased, whereas the molecular weight of wheat straw increased after pretreatment. Degradation and polymerisation reactions competed during pretreatment and the net effect depended on biomass type and pretreatment severity. Lignin-derived inhibition in Avicel hydrolysis strongly correlated with the binding and inactivation of the cellobiohydrolase TrCel7A to lignin. TrCel7A is the main component in the Trichoderma reesei cellulase cocktails. The correlation between enzyme binding to lignin and inhibition in hydrolysis was studied using six purified enzymes common in cellulase cocktails, cellobiohydrolases TrCel7A, TrCel6A, endoglucanases TrCel7B and TrCel5A, a xylanase TrXyn2 from T. reesei and a β-glucosidase AnCel3A from Aspergillus niger. The cellobiohydrolases, an endoglucanase and a xylanase were all inhibited by isolated lignin. Interestingly, the most thermostable enzyme AnCel3A exhibited minor binding to lignin and was, in fact, activated by lignin. The activation of AnCel3A was the result of soluble lignin-derived compounds. The enzymes TrCel6A and TrCel7B, which exhibited strong binding to thin lignin films as analysed by quartz crystal microbalance (QCM), were also the enzymes that were most inhibited by lignin in hydrolysis assays. The interactions contributing to enzyme binding to lignin were enzyme-specific, however, some common interactions were identified. Enzymes containing a carbohydrate binding module from family 1 (CBM1), TrCel7A, TrCel6A, TrCel7B and TrCel5A, exhibited greater adsorption to lignin than the enzymes without a CBM. Furthermore, enzymes having a net positive surface charge bound to lignin more than enzymes with a net negative surface charge in the experimental pH. Enzyme surface hydrophobicity was computationally determined. Enzymes containing large uniform hydrophobic patches on the enzyme surface had stronger binding to lignin as only a low amount of enzyme was released from the lignin surface during rinsing with buffer. Thermal stability had a profound effect on lignin tolerance for family GH11 xylanases. Two T. reesei xylanases TrXyn1 and TrXyn2 as well as two forms of a metagenomic xylanase Xyl40 were all inhibited by lignin in hydrolysis assays and bound to lignin after incubation with enzymatically isolated lignin from steam pretreated spruce. Interestingly, the thermostable xylanases Xyl40 produced in Escherichia coli and the catalytic domain of Xyl40 produced in T. reesei remained partially active on the lignin surface, whereas the thermolabile TrXyn1 and TrXyn2 became inactive. N-glycosylation of the catalytic domain of Xyl40 did not affect the hydrolysis yield but had a significant effect on lignin tolerance. The glycosylated xylanase achieved higher hydrolysis yields in the presence of lignin than the deglycosylated xylanase. High thermal stability and structural glycans improved the lignin tolerance of the xylanases studied.
  • Liu, Mengxia (Helsingin yliopisto, 2022)
    Norway spruce (Picea abies Karst) and Scots pine (Pinus sylvestris L.) are ecologically and economically important conifer species. The root and stem rot pathogens Heterobasidion annosum s.l. lead to severe diseases throughout European forests, resulting in an annual loss of approximately 50 million euros in Finland. In addition to chemical and biocontrol approaches, the application of resistant genotypes generated through breeding will play a potential role in controlling and managing the diseases. However, our understanding of the genetic factors that contribute to conifer resistance against Heterobasidion spp. is quite limited. The aim of this study was to identify molecular and chemical markers that correlate with phenotypic variation in disease resistance. Initially inducible defense mechanisms underlying resistance were evaluated through inoculating Norway spruce plants at three developmental stages (seedlings, young trees and mature trees) with H. parviporum. For constitutive resistance study, short-term resistance screening was conducted using needles of Norway spruce and Scots pine sampled prior to Heterobasidion spp. infection. Based on sapwood lesion area, resistant and susceptible genotypes were identified. The results revealed that conifer trees could initiate multiple defense responses against pathogen attacks, including necrosis and lesion formation together with increased cell death, increase of pH and peroxidase activity, and the induction of defense-related genes. Furthermore, certain monoterpene and sesquiterpene compounds affected inherent resistance. Monoterpenes such as bornyl acetate, camphene and β-pinene, and several sesquiterpenes were highly concentrated in resistant Norway spruce trees. Scots pine trees with enhanced resistance showed higher contents of 3-carene, whereas susceptible trees had higher α-pinene concentrations. RNA sequencing analysis showed that the expression of genes involved in lignin and flavonoid biosynthesis might influence resistance to H. parviporum in Norway spruce. Transcripts relevant to the abiotic and biotic stress interactions exhibited the possibility to increase susceptibility to H. annosum in Scots pine. The results revealed that even if Norway spruce and Scots pine share some common pathways in defense against necrotrophic Heterobasidion spp. infection, subtle inherent differences exist in their chemical and transcriptome response profiles. The results provide additional insights to serve as the foundation for future studies on the resistance of conifer trees to root rot pathogens.
  • Joensuu, Katri (Helsingin yliopisto, 2022)
    Agriculture has been shown to contribute to many global environmental problems, such as climate change and eutrophication. In order to control and decrease these environmental pressures, their magnitude needs to be assessed. One possibility is the use of life cycle assessment (LCA), which is a widely used method to quantify the environmental efficiency of products and production systems. The most widely used LCA methods include a variety of environmental impact categories, for example climate change, stratospheric ozone depletion, acidification, eutrophication and ecotoxicity. However, most of the methods were originally developed for the assessment of environmental pressures caused by industrial processes. They may, therefore, not be sufficient to describe the environmental pressures caused by agricultural production, which is largely based on biological processes. This dissertation aims to identify the most relevant environmental indicators for LCA of agricultural products and develop the assessment methods for novel environmental indicators related to soil quality and nutrient use efficiency for agricultural products in the context of LCA. First, relevant environmental sustainability indicators for agricultural production were identified based on a literature review. Second, the most important impacts of agricultural land use on soil quality were identified, and the applicability of existing assessment methods were evaluated. The most potential available assessment methods were tested in a case study using actual production data from Finnish farms. Third, a recently introduced nutrient footprint method was developed to apply to an animal food product – beef. Based on the results, the most relevant environmental sustainability indicators in LCA studies of agricultural products included greenhouse gas (GHG) emissions, eutrophication, biodiversity loss, toxicity, acidification, air quality and resource use efficiency indicators for land, water and energy use. It can be concluded that, despite the high importance of GHG emissions, several other indicators are also needed to give a comprehensive view of the environmental sustainability of an agricultural production system. Environmental sustainability indicators related to soil quality, such as soil organic matter (SOM) loss and erosion, were found to be neither routinely used in LCA studies nor very clearly addressed by general LCA methods. Furthermore, many of the existing methods developed for soil quality indicators were found to not be very useful in situations in which the goal of the study is assessing the direct impacts of different agricultural management practices. Suitable methods do, however, exist for assessing the soil quality indicators of soil erosion, SOM loss and soil compaction. The use of nutrients, such as nitrogen (N) and phosphorus (P), was not among the most frequently used environmental sustainability indicators. It was found not to be addressed sufficiently in the general LCA methods. However, as an additional indicator, the nutrient footprint would bring added value in that it includes all nutrient flows related to the production chain under study, from various nutrient input sources to nutrient emissions. In summary, soil quality aspects and the nutrient footprint could be included as midpoint indicators in LCA methods. They would give a more comprehensive view of the environmental impacts and resource use efficiency of agricultural production chains than the currently used LCA impact categories such as GHG emissions and eutrophication.
  • Kalu, Subin (Helsingin yliopisto, 2022)
    Biochars are highly stable porous carbon-rich substances that, when added to soils, have high potential to increase soil carbon (C) sequestration, enhance soil fertility and crop yield, as well as bring other environmental benefits such as reducing emissions of greenhouse gases (GHG) and leaching of nutrients, and remediation of soils contaminated with heavy metals. The potential of biochars to provide agricultural and environmental benefits had led to an exponential increase in the number of studies on the effects of biochars since the beginning of this century. However, the long-term effects of a single application of biochars are not well known. In addition, the beneficial effects of biochars have been observed mostly in (sub-) tropical regions dominated by highly weathered, nutrient-poor acidic soils with low C contents. On the other hand, only a few studies have been conducted on boreal soils that typically have higher C contents. Therefore, this research aimed to investigate the long-term effects of wood-based biochars when combined with different fertilizers in boreal agricultural soils, in terms of i) plant growth and nutrient uptake, ii) soil physical properties, iii) nitrogen (N) dynamics, and iv) GHG emissions. For this, data were collected from four field experiments in Finnish soils, where biochars were applied two to eight years prior to this research, as well as from a greenhouse experiment. Over the eight years of field experiments, the biochars had minor effects on plant growth and nutrient uptake in both nutrient-poor and nutrient-sufficient soils. Throughout this period, the biochars increased plant growth only on two occasions. On both occasions, the fields were cropped with nitrogen-fixing plants in the previous growing season, thus suggesting that the result may be explained by pre-crop effects. The biochars notably increased plant potassium (K) uptake while reducing plant aluminum (Al) and sodium (Na) uptake, indicating that biochars can ameliorate plant K deficiency, and reduce Al and Na toxicity stress. The biochars increased the contents of several nutrients in plant biomass with time, suggesting a possible long-term fertilization effect either through the slow release of nutrients initially contained in biochars or via the enhanced nutrient holding capacity of biochars as they weather in the field. On the other hand, the biochar reduced plant manganese (Mn) content with time in a nutrient-poor soil, suggesting that immediately after application, the biochar increased plant availability of Mn (either present in the biochar or soil), which decreased over the years. After six or seven years of application, the biochars did not affect the physical or hydrological properties of topsoil. Immediately following the application, the biochar had increased plant available water in coarse-textured soil. However, this effect disappeared with time, which could be caused by the loss of the biochar or the movement of biochar down the soil profile. The biochars were shown to have nitrate (NO3-) retaining capacity in both the short-term greenhouse experiment and in the field experiment in clayey soil where spruce and willow biochars were applied two years before. The increased N use efficiency, increased plant N uptake, and reduced N leaching by biochars in these experiments were most likely due to the increased retention of NO3- by the biochars. The spruce biochar was better than the willow biochar in NO3- retention, most likely because of the higher specific surface area. The 15N labeling greenhouse experiment suggested that biochars could induce ammonia volatilization that leads to the loss of fertilizer ammonium (NH4+) because of increased soil pH. On the other hand, the ability of biochars to retain NO3- increases the soil retention and plant uptake of NO3-. Furthermore, there was an indication that biochars increased the plant N availability via increased mineralization of soil organic N in the short-term. The biochars increased carbon dioxide (CO2) efflux from two out of the four field experiments. In addition to the increased soil microbial activity, the increased plant growth might have contributed to increased CO2 efflux. However, there were no clear effects of biochars on the emissions of nitrous oxide (N2O) and methane (CH4) in any of the fields. Despite this, the spruce and willow biochars tended to reduce N2O emission during the peak emission period after two years. The potential of biochars to reduce N2O emission appeared to be dependent on soil silt content and initial soil C content. Interestingly, the wood-based biochar reduced the yield-scaled emissions of non-CO2 GHG in the field experiment on coarse-textured soil, even after seven years of application. The reduction was mostly due to the increased crop yield, which could be a result of the increased availability of plant water by biochar during the extremely dry growing season. Overall, no negative effects of biochars were observed in the greenhouse or the longer-term field experiments in boreal soils. Therefore, this research supports the concept that biochars as soil amendment materials are a safe and practical way to increase soil C sequestration. However, achieving consistent noticeable agronomic and other environmental benefits after several years of a single application of wood-based biochars is implausible in boreal soils. Thus, subsequent application of nutrient-rich biochars, such as co-composted biochars likely provides a more reasonable alternative for a consistent increase in soil C sequestration, as well as agronomic benefits. Future biochar research should focus on this direction.​
  • Kavlak, Alper Tuna (Helsingin yliopisto, 2022)
    A major proportion of the costs of pork production is related to feed; thus, improving feed efficiency is one of the most important breeding goals in pig breeding programs. Feed efficiency measurements are based on the performance of pigs in a controlled test station environment with an automatic feeding system. During the test period, a large amount of feeding-related information, including time entering the feeder, time leaving the feeder and amount of feed consumed, are gathered. These data can be used to form different feeding behaviour traits (FBT) such as daily feed intake (DFI) or feed intake per visit (FPV). During the test period, pigs are group housed. Therefore, social behaviour between pen mates may affect feeding behaviour, production traits (PT) and welfare of other pen mates. Furthermore, unusual or radical changes in pigs’ behaviour can be a sign of diseases or discomfort and can be used for the detection of diseases for timely intervention. The thesis has three objectives. The first objective was to estimate the heritability of FBT and their correlation with PT in the Finnish Yorkshire pig population (I). The second objective was to estimate genetic parameters of feeding behaviour and PT in Finnish pig breeds using a model with a social genetic effect (SGE; study II). The third objective was to develop machine learning methods for detection of pigs that may need medical treatment or extra management based on changes in their feeding behaviour patterns (III). The data consisted of purebred Finnish Yorkshire and Finnish Landrace pigs and their F1-crosses. Pigs were raised in a controlled test station environment located in Längelmäki, Finland (Figen Oy). Pigs arrived at the test station at an average age of 89 ± 10 days (mean ± standard deviation) and an average weight of 34.7 ± 6.4 kg. The slaughter age was 186 ± 10 days, and the slaughter weight was 121.2 ± 12.9 kg. The feeding, production and sickness data were collected from 10,275 pigs that had entered the test station between 2011 and 2016 (October). From obtained feeding observation, daily values were calculated as the number of visits per day (NVD), time spent in feeding per day (TPD), DFI, time spent feeding per visit (TPV), FPV and feed intake rate (FR). The final records of FBT were calculated as averages of the daily records separately for the five testing time periods: 0 to 20 days (period 1), 21 to 40 days (period 2), 41 to 60 days (period 3), 61 to 80 days (period 4) and 81 to 93 days (period 5). The PT were average daily gain (ADG), feed conversion rate (FCR) and backfat thickness (BF) as well as residual feed intake (RFI), which was calculated as the difference between the observed and predicted DFIs. For the last objective, daily observations of the health status of pigs (794,509 daily observations) were used. The data included 13,018 observations of symptoms (cough, limp, loss of appetite, skin damage, bitten tail). Pigs with symptoms were classified as “sick” while the pigs with no symptoms were classified as “healthy”. For the first objective (I), a univariate animal model was applied for the estimation of heritability of FBT and PT and a bi-variate model for the estimation of genetic correlations between the traits. For the second objective, single-trait social genetic models were applied with two different group size parametrisations: a fixed group size with a random sampling of eight pigs for each pen and a variable group size model where the number of pen mates varied. The restricted maximum likelihood (REML) method and the DMU software were used for the variance component estimations (I and II). For the last objective, the machine learning algorithm (Xgboost) was designed with different window lengths (one-day, three-day and seven-day window lengths) using features calculated from the feeding data to predict the individual health status (sick or healthy). Heritability estimates for FBT and PT were moderate (around 0.3). Only the DFI had strong genetic correlations with PT (e.g., over 0.8 with RFI). Interestingly, the FR and FPV were associated with BF in early testing time (I). The SGE was significant for FBT and the FCR but not for the ADG and BF (II). For those traits, the total heritable variation was considerably higher than the pure classical heritability. The fixed and variable group size models produced very similar estimates (II). Using the Xgboost machine learning method, the best performance for predicting pigs’ daily health status was obtained with a seven-day window length (80% area under the Receiver Operator Characteristics (ROC) curve) [AUC], 7% F1-score, 67% sensitivity and 73% specificity). However, the precision was very low (0.04), possibly due to an imbalanced dataset (III). In conclusion, results indicate that the FBT are moderately inherited but their correlation with PT are weak; thus, FBT are not important in breeding programs. The social genetic component was important in FBT but also in the FCR; thus, applying SGEs in breeding value estimation would increase the accuracy of selection for the FCR. Predictions based on changes in feeding behaviour can help in the detection of sick pigs, leading to better pig welfare and increased sustainability of pork production.

View more