Maatalous- metsätieteellinen tiedekunta


Recent Submissions

  • Mousavi, Seyed Abdollah (Unigrafia, 2016)
    ABSTRACT Studies of the taxonomy of bacteria were initiated in the last quarter of the 19th century when bacteria were classified in six genera placed in four tribes based on their morphological appearance. Since then the taxonomy of bacteria has been revolutionized several times. At present, 30 phyla belong to the domain Bacteria , which includes over 9600 species. Unlike many eukaryotes, bacteria lack complex morphological characters and practically phylogenetically informative fossils. It is partly due to these reasons that bacterial taxonomy is complicated. Due to the improvement of methods to obtain sequence level characters plus new methods for their analyses, the taxonomy of bacteria has also been improved. However, there is still no official classification of prokaryotes. Biological nitrogen fixation (BNF) is a process in which bacteria reduce inert nitrogen gas to biologically useful ammonia. The symbiotic interaction between rhizobia and legumes (Fabaceae or Leguminosae) is important both in natural systems and in agriculture. Rhizobia is a general name for a group of bacteria that can enter symbiosis with legumes. Until 1982, all these were classified into one single bacterial genus, Rhizobium. The number of rhizobial genera increased to 17 by the year 2011, from which five genera, Rhizobium, Allorhizobium, Agrobacterium, Ensifer (syn. Sinorhizobium), and Shinella were accommodated in the family Rhizobiaceae. The genus Agrobacterium, a group of mostly pathogenic bacteria, was placed among the beneficial nitrogen-fixing bacteria (rhizobia) in the family Rhizobiaceae. That resulted in several taxonomic issues regarding the family Rhizobiaceae. The main nomenclatural issue regarding the genus Agrobacterium resulted from transferring this genus to the genus Rhizobium. Moreover, the phylogenetic position of the former nitrogen-fixing Rhizobium galegae complex was not clear. This group of bacteria was in previous studies clustered with either Agrobacterium or Rhizobium or placed in a lineage separately from other genera of the family Rhizobiaceae. During the last decade, the number of the rhizobial species increased dramatically, especially in the genus Rhizobium. However, Rhizobium is an inappropriate genus name for some of the species assigned to the genus. To resolve some of the major taxonomic uncertainties of the family Rhizobiaceae, two separate multilocus sequencing analyses (MLSA) were performed. In the first study, an MLSA of 114 rhizobial strains was performed by using six housekeeping genes (atpD, glnA, glnII, recA, rpoB, and thrC). The first MLSA study was focusing on the phylogeny of the taxa belonging to the former Rhizobium galegae complex and the genus Agrobacterium. In the second MLSA, a total of 100 strains representing 81 species of the family Rhizobiaceae were studied using four housekeeping genes namely 16S rRNA, atpD, recA, and rpoB. Based on these results, we proposed delineation of two new genera, Neorhizobium gen. nov. and Pararhizobium gen. nov., and 16 new species combinations, Neorhizobium galegae comb. nov., Neorhizobium huautlense comb. nov., Neorhizobium alkalisoli comb. nov., Agrobacterium nepotum comb. nov., Agrobacterium pusense comb. nov., Agrobacterium skierniewicense comb. nov., Allorhizobium vitis comb. nov., Allorhizobium taibaishanense comb. nov., Allorhizobium paknamense comb. nov., Allorhizobium oryzae comb. nov., Allorhizobium pseudoryzae comb. nov., Allorhizobium borbori comb. nov., Pararhizobium giardinii comb. nov., Pararhizobium capsulatum comb. nov., Pararhizobium herbae comb. nov., and Pararhizobium sphaerophysae comb. nov. (Paper I and II). A total of 159 bacterial strains were isolated from the nodules of the Chinese specimens of the plant genus Glycyrrhiza L. The results of the study showed that 29 true symbiotic strains belong to the genus Mesorhizobium. To estimate the phylogenetic position of the 29 isolates an MLSA was performed for 59 mesorhizobial strains by using three housekeeping genes 16S rRNA, recA, and rpoB. Moreover, the phylogeny of three symbiotic genes (nodA, nodC, and nifH) of these 59 mesorhizobial strains was investigated. The results of MLSA showed that 21 test strains belong to the species M. tianshanense, M. gobiense, M. temperatum, M. muleiense, M. amorphae, M. alhagi, and M. camelthorni, whereas eight test strains might belong to a novel species of Mesorhizobium. The results of the analyses of accessory genes in this study showed that the mesorhizobial strains isolated from the plant genus Glycyrrhiza have probably acquired some genetic material from other rhizobia co-evolving with Glycyrrhiza and other legumes (Paper III).
  • Vehkaoja, Mia (Hansaprint Oy, 2016)
    Wetland and deadwood loss have had a profound effect on boreal aquatic and terrestrial ecosystems and their biodiversity. Deadwood-dependent species are one of the most endangered organism groups in the world, while amphibians on the other hand excellently represent the ecological state of wetlands. The boreal region contains a large proportion of the world s wetlands, which have undergone two major alterations during the last 500 years: first the extirpation of beavers and secondly draining during the 20th century. Beavers are well-known ecosystem engineers of the Northern Hemisphere. They modify their surroundings by damming water systems. Damming raises flood waters into the surrounding riparian forest and changes environmental conditions both on land and in water. Ecosystem processes are altered when beavers turn a lotic water system into a lentic one, but the alteration is also evident when beavers modify initially lentic water systems. Organic matter and nutrients are transferred into a wetland from beaver-felled trees and vegetation killed by flooding. The amount of dissolved organic carbon increases during the first three impoundment years, which enhances the growth of aquatic vegetation and the abundance of phyto- and zooplankton, thereby also increasing invertebrate abundances. Luxuriant vegetation and ample plankton and invertebrate populations facilitate frogs, which become abundant in beaver wetlands. The moor frog in particular favours beaver-created wetlands. Flooding and beavers kill trees, producing high amounts of deadwood. The riparian forests of beaver wetlands include much higher deadwood levels than wetlands without beavers. Increased deadwood creates substrate resources for deadwood-dependent species. Snags are a typical deadwood type in beaver wetlands. Calicioids are deadwood-dependent species particularly specialised in inhabiting standing deadwood. The comeback of beavers has aided the restoration of wetlands and deadwood. Beaver wetlands can be seen as carbon and biodiversity hot spots that increase the heterogeneity and hydraulic connectivity of the boreal landscape.
  • Muziasari, Windi (Helsingin yliopisto, 2016)
    Antibiotic resistance has become a serious threat to the efficacy of antibiotics used in human and veterinary medicine. Understanding the abundance and prevalence of antibiotic resistance genes (ARGs) in the environmental resistome is important for maintaining the efficacy of antibiotics and predicting a risk of the ARGs spreading in the environment and moving into previously non-resistant bacteria, including human pathogens. Fish farms are an environmental reservoir of ARGs due to the treatment of fish with antibiotics that also are important for human medicine. The two main topics of this thesis are (1) determining the abundance and diversity of ARGs and mobile elements in sediments impacted by fish farming and (2) investigating the major source of ARGs in the farm sediments in the Northern Baltic Sea. In addition, correlations between ARGs and mobile elements were examined to estimate the potential risk of ARG mobilization in the environment. This study employed a high-throughput qPCR array, which permits quantifying hundreds of ARGs and genes associated with mobile elements in the environmental resistome in a single experiment. Fish farming impacts the composition of ARGs in sediments below fish farms in the Northern Baltic Sea. However, the impact is local and mostly limited to enrichment of ARGs associated with antibiotics used at the farms. In the current conditions, the risk of ARG spread from the farm sediments to the surrounding sediments is low in the Northern Baltic Sea. However, the enriched ARGs persist in the farm sediments during the 6-year observations even when the selection pressure of the antibiotics is negligible. Moreover, significant correlations between mobile elements and ARGs may imply the persistence of certain ARGs in the fish farming environments and their potential for mobilizing the ARGs to other bacteria including pathogens. The persistence of ARGs at the farm facilities is a threat to the efficacy of the antibiotics against fish diseases, potentially leading to fish production losses. We provide indirect evidence suggesting that certain ARGs are being constantly introduced by feces of the farmed fish into the sediments below the fish farms. Further studies could focus on investigating the development of ARGs in juvenile fish before they are introduced into the Baltic Sea open-cage farms. We conclude that a high throughput qPCR array is a powerful tool that provides unprecedented insights into the ARG composition in the environmental resistome associated with fish farming.
  • Besong-Ndika, Jane E. (Helsingin yliopisto, 2016)
    The present study intended to identify new strategies for the selective presentation of biocatalyst on the surface of viral nanoparticles with potential application in biosensor technology or protein chips. Potyviruses were chosen as model nano-scaffolds for biocatalysts. Potyviruses are the largest genus in the family Potyviridae and cause significant plant damage. They form flexible rod-shaped capsids surrounding a single stranded positive sense RNA molecule. The molecular events leading to the specific selection and encapsidation of potyviral RNA are unknown. To better exploit the potential of these viruses as nano-carriers, the first step in this study was to look into their in vivo RNA encapsidation process. Earlier studies showed that Potato virus A (PVA) coat protein (CP) interferes with viral RNA translation when provided in excess in trans and it was suggested this could occur to initiate viral RNA encapsidation. In this follow up study, we used the ago-infiltration approach for the transient expression of full length, truncated or mutated viral RNAs with wild type CP (CPwt) and showed that this inhibition is mediated by co-translational CP-CP interactions occurring between two CP populations, produced in trans and in cis. Because CP inhibited translation of the entire viral genome and virus particles were formed (which were less abundant and appeared latter than during normal infection), it was assumed that the CP acted during this inhibition process to specifically recruit viral RNA for encapsidation. In line with previously published in vitro assembly studies, we propose a mechanism through which viral RNA encapsidation is initiated through co-translational CP-CP interactions. The second part of this work entailed the investigation of novel approaches for organizing biocatalyst on virus platforms. The aim was to be able to control the display of enzymes on virus surfaces while maximizing channelling of reaction intermediates. Three strategies were investigated: the first involved the use of specific PVA CP binding peptides selected by phage display, the second involved the use of heterodimeric leucine zippers and the last involved the use of an antibody binding peptide, the z33 peptide, from Staphylococcus aureus. The first two strategies were unsuccessful. On the other hand, the z33 strategy enabled an 87 % occupancy of accessible sites on the potyvirus particles by the enzyme. To further test the potential of potyviruses as multi-enzyme nano-carriers, two enzymes, 4-coumarate:coenzyme A ligase (4CL2) and stilbene synthase (STS), catalyzing consecutive steps in resveratrol synthetic pathway were employed as model biocatalysts. The z33-peptide was fused to the N-terminus of these enzymes, z4CL2His and zSTSHis and a chimera-protein, z4CL2::STSHis was also generated by the genetic fusion of both enzymes. All enzymes were active and resveratrol was synthesized from both mono-enzymes and the protein chimera either in solution or adsorbed on potyvirus particles. The latter was illustrated by trapping the mono-enzymes or the protein chimera from clarified soluble E. coli cell lysates on to the surface of potyvirus particles immobilized on the surface of a polypropylene tube. This strategy brings together a bottom-up and top down approach for designing virus based nano-materials and offers a cost effective and efficient way to co-immobilize and purify enzymes.
  • Rommi, Katariina (VTT Technical Research Centre of Finland Ltd, 2016)
    New protein sources are needed to fulfil the growing global demand for food protein. The co-stream from cold pressing of rapeseed oil, press cake, is a rich source of protein (32 26%) with good nutritional value. Several technologies based on alkaline or saline extraction have been developed for enrichment of rapeseed protein, but high energy and water consumption due to dilute conditions and multiple processing steps limit their sustainability and profitability. In the present study, enzyme-aided methods for extraction of protein from rapeseed cold-press cake were developed, and factors influencing protein extractability and properties of the obtained protein-rich fractions were elucidated. Pretreatments and carbohydrate-hydrolyzing enzyme treatment were used to facilitate extraction at reduced water content and without chemicals such as alkali or salt. Particularly a pectinase preparation with β-glucanase side activity enabled effective hydrolysis of rapeseed cell wall polysaccharides, increasing protein recovery by aqueous extraction. Similar improvement of protein extractability was, however, not achieved by mechanical cell wall disruption, suggesting that protein release was not to a major extent physically hindered by the residual cell structures in the press cake. Instead, enzyme treatment reduced the water holding capacity of the press cake and released hydrolysis products which are suggested to have enhanced the solubility of rapeseed protein during water extraction. At 10% solid content, enzyme-aided water extraction produced protein-enriched fractions with a similar yield and estimated production costs as conventional alkaline extraction (pH 10) and isoelectric precipitation. Techno-economic evaluation of different extraction schemes also suggested substantial reduction of energy costs when the extraction was carried out at 20% solid content. Due to the co-extraction of carbohydrates, enzyme-aided protein extraction was less selective than non-enzymatic alkaline extraction and isoelectric precipitation. On the other hand, carbohydrates are suggested to have improved the solubility and dispersion stability of protein extracts by electrostatic interactions. The results indicate that enzyme-aided fractionation methods are suitable for rapeseed protein production and may offer a techno-economically feasible alternative to alkaline or saline extraction. Additionally, protein hydrolyzates were extracted from dry-fractionated rapeseed press cake by proteolytic enzyme treatment. The hydrolyzates showed high inhibition of radical-induced oxidation in vitro, and their observed antioxidativity correlated with their protein and sinapic acid concentration. The hydrolyzates were also able to inhibit the myeloperoxidase and elastase enzymes involved in inflammation and skin aging, therefore having novel application potential as active ingredients or natural preservatives in skin care products.
  • Kylä-Nikkilä, Kari (Helsingin yliopisto, 2016)
    Mankind has exploited lactic acid bacteria for thousands of years. For most of this time, the use of these bacteria was based on tradition without deeper knowledge of the nature of these organisms. Nowadays, we have learned to know lactic acid bacteria and we are capable to genetically modify these organisms. In this thesis, methods to modify Lactobacillus helveticus bacterium to produce optically pure L(+)-lactic acid are introduced. Also, a method to immobilize lactic acid bacteria on unmodified cellulosic material is described. Lactic acid has two optical isomers: D(-)-lactic acid and L(+)-lactic acid. Most typically lactic acid is produced by microbial fermentation process. When using strains belonging to genus Lactobacillus in these fermentations, the produced lactic acid is most typically mixture of D(-)- and L(+)-lactic acid. In certain industrial applications, like that of the production of biodegradable plastic, pure L(+)-lactic acid is the preferred choice to be used as a raw material. In this work, two novel Lactobacillus helveticus strains were constructed for this purpose. As demonstrated by experiments, both these strains are potential producers of plastic grade L(+)-lactic acid. In many industrial-scale fermentation processes, it is beneficial to immobilize production strain on a solid carrier, whenever possible. From economical point of view, this kind of approach is very attractive especially if the immobilization is possible to carry out with minimal use of chemicals and processing steps. In this work Lactococcus lactis was genetically engineered to provide binding to chemically unmodified cellulosic carrier material. Putatively, by applying this method in an industrial-scale setup, it is possible to develop novel continuous fermentation processes.
  • Matthies, Brent (Helsingin yliopisto, 2016)
    The ecosystem service (ES) approach is a means of evaluating service value flows from ecosystems to humans for their well-being. The approach suggests that ecosystem functions are divided into categories according to the benefits derived and utilized by beneficiaries. The ES approach has become a tool for public and private decision-makers, driven by the need to more accurately incorporate environmental externalities into the value creation processes of economic actors. This research addresses two knowledge gaps within the ES literature. First, a service-centric approach to ES offerings is lacking, resulting in misuse of the appropriate concepts and terms when discussing their role in value networks and value creation. Second, there is limited available knowledge about how to efficiently internalize ES offerings within value networks. In the first article, a service-dominant value creation (SVC) framework, with supporting terms and concepts, was developed to guide interdisciplinary discussions about the role of ES offerings within value creation processes. The term value-in-impact was proposed as a means for discussing the trade-offs and impacts concerning ES offerings within those processes. The subsequent three articles addressed the following design aspects of Payment for Ecosystem Service (PES) schemes: (1) sensitivity to parameter inputs, (2) price volatility impacts on service providers, and (3) behavioural economic contributions. Consideration for trade-offs among ES offerings, and between ES offerings and economic objectives were also incorporated. The results indicated that the holistic accounting of ES indicators, to determine the optimal species mixtures, and uncorrelated ES price interactions, to determine the optimal allocation of forest for conservation, led to ecological and financial diversification benefits for service providers. Nudging service providers also led to more socially efficient ES provisioning. In each case, the proposed Ecosystem Service Expectation Value (ESEV) was used to more accurately describe the perpetual provisioning of multiple ES offerings on forestland.
  • Toivonen, Marjaana (Helsingin yliopisto, 2016)
    Environmental fallows are fields that aim to produce environmental benefits instead of agricultural products. In many European countries, the establishment and management of fallows is funded via agri-environmental programmes. This thesis focuses on the biodiversity benefits of environmental fallows in boreal farmland. I examined the impacts of different fallow types and landscape structure on the diversity and species composition of multiple taxa in fallows. I also aimed to evaluate what fallow types, and in what landscape context, are needed to contribute to different biodiversity objectives: the promotion of conservation concern species, overall species diversity or ecosystem services. Species richness and composition of the studied species groups differed substantially between fallow types, and landscape context further modified the value of fallows. Perennial fallows sown with meadow plants supported high plant species richness and bumblebee abundance. Old grassland fallows benefitted both butterflies in general, and butterflies and bumblebees with narrow niches and low dispersal capacities. The positive impacts were emphasized when long-term fallows were located in complex landscapes. High forest cover in the surrounding landscape increased plant species richness in perennial fallows. The breeding density of open farmland birds was highest in short-term meadow fallows in landscapes rich in perennial grasslands. Foraging edge birds preferred short-term meadow fallows in open landscapes and long-term grassland fallows in forested landscapes. Vegetation of annual fallow types game fields and landscape fields differed considerably from perennial fallows and other non-crop biotopes, thus enhancing landscape heterogeneity. My results show that the biodiversity benefits of fallows can be enhanced by adapting fallows to the landscape context and to specific conservation objectives. If the objective is to support species of conservation concern, managing long-term fallows in complex landscapes rich in perennial grasslands is probably the best strategy. Overall biodiversity can also be enhanced in short-term fallows, especially if they are sown with diverse seed mixtures of species that are not too competitive in field conditions. Depending on the sown species, short-term fallows provide good possibilities to enhance landscape heterogeneity and promote ecosystem services. Future studies should consider the specific roles of forest and perennial grasslands in driving the effectiveness of agri-environment schemes. In addition, the impacts of agri-environment schemes, including fallows, on realized ecosystem services should be investigated.
  • Korhonen, Jaana (2016)
    International industrial competitiveness depends on many aspects. It can be based on cost advantages over international competitors, which are realized as higher market shares and increased trade flows in global markets. Competitiveness can also be improved by creating higher value through increased product quality and by means of sustainability. This places increasing strategic importance on scarcening natural resources and on how proactively environmental responsibility is perceived in the international forest sector in the future; as an additional cost or more as an opportunity of a high road to competitiveness? The goal of this dissertation is to analyze international competitiveness and its drivers from five different perspectives at the regional, country, and firm levels, with an emphasis on the pulp and paper industry. The empirical research problems of five individual research articles are approached by combining quantitative and qualitative data analyses. The time period from 1990 to 2030 was covered in the analyses. The results highlight the importance of forests, markets, and regulation in creating competitive advantages at different levels in the sector. The traditional forest sector factors such as resource availability and traditional economic factors such price competitiveness are going to play an important role also in the future. However, sustainability will become increasingly important for the value creation opportunities of industries. It is an opportunity for companies in their global value chains if the global environmental awareness and societal demand for sustainability continue to increase. Therefore, more responsible use of global forest resources can offer solutions to global sustainability challenges, and in the transition to a bioeconomy in which the forest industry plays a key role.
  • Etongo Bau, Daniel (Helsingin yliopisto, 2016)
    Tropical deforestation and forest degradation (DD) contribute approximately 15% of the annual global anthropogenic greenhouse gas (GHG) emissions. However, they are considered the main emissions sources in most developing countries. Despite the potentials of forest and tree plantations to mitigate the effects of climate change through carbon sequestration, DD still remains a challenge in Africa. Globally, the forests of Africa are the most depleted of all tropical regions, with only 30% of historical forest area still remaining. In addition, Africa s complexity in terms of its geography, politics, socioculture, economy, institutions etc. is an indication of why Africa has defied all simple solutions in addressing DD: a phenomenon considered location- and situation-specific. The biophysical setting of Burkina Faso exposes the central and northern region to drought and desertification. Such conditions have caused human migration to the southwestern regions, which offer better opportunities for rain-fed agriculture, but also experiences the highest rates of deforestation. On the other hand, the ongoing regreening process in the Sahel through tree planting and assisted natural regeneration of indigenous tree species is a signal for regrowth and revegetation. This study contributes to understanding the drivers of DD in four adjacent village communities in the Ziro province, southern Burkina Faso in the light of the forest transition theory. Specifically, this study assesses the drivers of DD at the farm/forest level and also identifies options for regrowth/revegetation. This dissertation consists of four articles (studies I, II, III, and IV). Studies I and II refer to stage two of the forest transition curve (forest frontier) while studies III and IV refer to stage four of the curve (forest/plantations/agricultural mosaics). Various methods were used during data collection, including interviews with key informants, focus group discussions (FGDs), two hundred household interviews (studies I, II, and III), gathering a list of local botanical knowledge from 48 participants (study IV), and a field survey. Qualitative and quantitative methods were used in analyzing the data. Low agricultural production expressed in the sizes (areas) and ages of farms together with land tenure insecurity were found to lead to increased deforestation. Results suggested that a 10% increase in farm size would result in a 4% increase in annual deforestation (study I). Furthermore, results in study II indicated that non-poor and fairly poor farmers contributed more towards activities considered environmentally degrading, such as deforestation, overgrazing etc., than the poorest farmers. On the other hand, the adoption of sustainable land management practices was relatively low among the poorest farmers. Tree planters were mainly farmers who held large and old farm areas, were literate and relatively wealthy, held favorable attitudes towards tree planting, and had participated in a farmers group for several years (study III). Local knowledge of tree species was found to be unevenly distributed in relation to gender, age, ethnic group, and location. Plant species assigned relatively high use-values for livelihood include Adansonia digitata, Parkia biglobosa, Vitellaria paradoxa, and Balanites aegyptiaca. On the other hand, Adansonia digitata, Tamarindus indica, and Ficus thonningii were considered more important for environmental protection (study IV). The dissertation concludes that tenure insecurity and low agricultural production contribute to DD at the farm/forest level on the one hand while tree plantations, land management practices, such as fallow, zai pits (a traditional soil and water conservation technique), and assisted natural regeneration of indigenous tree species are important activities promoting regrowth/revegetation.
  • Kasurinen, Ville (Finnish Society of Forest Science, 2016)
    Water and carbon cycles of the Earth are tightly linked to each other. One linkage of these cycles is through the water use efficiency of photosynthetic production its interactions with drought, and its possible changes. A second linkage between the water and carbon cycles: the transport of terrestrial carbon as dissolved organic carbon (DOC) to aquatic ecosystems has received much less attention and is, therefore, the subject of this thesis. The thesis shows that latent heat exchange in boreal and arctic biomes differs, under similar climatic conditions, between different land cover types in the boreal and arctic climatic zones. Furthermore, we found that there are large differences in the way ecosystems are exchanging water in the winter and the summer. Winter time surface resistances were much higher and the transition between the winter and summer phenological stages was slow. Similarly, stream water DOC concentrations show high temporal and spatial variability between different catchments in boreal landscapes and globally between big river systems. The model, developed here and applied to a boreal catchment simulates stream water DOC concentrations as a function of catchment water storage, soil temperature and runoff. The model is parsimonious, i.e. all parameters could be estimated statistically and it its performed better than previous models for the 18 partially nested sub-catchments of the Kryckland research area. Finally, the contribution of terrestrial DOC promoting heterotrophic food webs in coastal waters was quantified after receiving a radiation dose corresponding UV-radiation absorbed by Earth s surface in a month. Irradiation removed approximately half from the initial terrestrial chromophoric dissolved organic matter (tCDOM) suggesting that sun-light induced photochemistry is a significant sink of tCDOM in coastal waters. Tropical rainforest covered large basins of Amazon and Congo Rivers contributed the highest production of biologically labile photoproducts (BLPs) and the highest tCDOM fluxes of investigated rivers, which might be linked to large water fluxes and carbon sequestration in their basins. A strong relationship between photobleaching of tCDOM and bacterial production based on bioavailable labile photoproducts (BLPs) was found and used to estimate BLP production globally. Extrapolation of production revealed that the majority of tDOC will be mineralized to CO2 either directly or through bacterial respiration in coastal waters. In these research articles, I have investigated biogeochemical cycles of water and carbon focusing to latent heat exchange and DOC dynamics in landscapes, as well as, in coastal waters, describing their variability across space and time.
  • Saarinen, Ninni (Helsingin yliopisto, 2016)
    Accurate and up-to-date information concerning vegetation characteristics is needed for decision-making from individual-tree-level management activities to the strategic planning of forest resources. Outdated information may lead to unbeneficial or even wrong decisions, at least when it comes to the timing of management activities. Airborne laser scanning (ALS) has so far been successfully used for applications involving detailed vegetation mapping because of its capability to simultaneously produce accurate information on vegetation and ground surfaces. The aim of this dissertation was to develop methods for characterizing vegetation and its changes in varying environments. A method called multisource single-tree inventory (MS-STI) was developed in substudy I to update urban tree attributes. In MS-STI stem map was produced with terrestrial laser scanning (TLS) and by combining the stem map with predictors derived from ALS data it was possible to obtain improved estimates of diameter-at-breast height but also to produce new attributes such as height and crown size. Boat-based mobile laser scanning (MLS) data were employed in substudy II to map riverbank vegetation and identify changes. The overall classification accuracy of 73% was obtained, which is similar to accuracies found in other studies. With multi-temporal MLS data sets changes in vegetation were mapped year to year. In substudy III, open access ALS data were combined with multisource national forest inventory (NFI) data to investigate the drivers associated to wind damage. The special interest was in ALS-based predictors to map areas with wind disturbance and apply logistic regression to produce a continuous probability surface of wind predisposition to identify areas most likely to experience wind damage. The results demonstrated that a combination of ALS and multisource NFI in the modelling approach increased the prediction accuracy from 76% to 81%. The dissertation showed the capability of ALS and MLS for characterizing vegetation and mapping changes in varying environments. The developed applications could increase and expand the utilization of multi-temporal 3D data sets as well as increase data value. The results of this dissertation can be utilized in producing more accurate, diverse, and up-to-date information for decision-making related to natural resources.
  • Huovila, Janne (Helsingin yliopisto, 2016)
    Public representations of healthy eating have been shifted to value more individualistic conceptualizations. Nevertheless, it is unclear how these conceptualizations are constructed. In this doctoral thesis, the main goal is to investigate how a more individualistic understanding of healthy eating is epistemically constructed and rhetorically made credible in media publicity. The thesis contains three case analyses. The first case involves an investigation into the debate about the low-carbohydrate diet in the Helsingin Sanomat newspaper. The second case compares the argumentation of six highly popular Finnish nutrition counselling bloggers to the argumentation of two academic experts contributing to the blog of the National Institute for Health and Welfare. The third case analysed the narrative construction of diet knowledge by academically-educated experts in blogs and the Finnish Medical Journal. The main finding was to identify the rationality - termed the sense of casuistry - that put together the epistemic and rhetorical aspects about the individualization of healthy eating. The sense of casuistry defined the basis of proper diet and eating habits valuing physiological, psychological and lifestyle differences between individuals. The sense of casuistry was constructed epistemically and, especially, rhetorically in a critical relationship to the common public health thinking which argues for population-based averages and risks. The rhetorical power of the casuistry was established through old cultural resources: clinical reasoning and common sense understanding about the differences between individuals. It was also influenced, however, by new cultural shifts, especially in media publicity, which emphasize personal experience and contextual factors in nutrition science instead of consensus statements. Individualization of healthy eating in public representations does not exemplify the clear distinction between scientific and unscientific knowledge. Because of this, individualization challenge to redefine expert communication: in contemporary media publicity, it is crucial to argue not only through the epidemiological rationality about risks and probabilities, but also in relation to casuistical reasoning, or a part of it. The methodological contribution of the study brings multidisciplinary epistemological framework together with discursive analysis regarding diet knowledge. For understanding the complex basis of diet knowledge in contemporary global and networked media publicity, it is important to combine the discursive approach on diet knowledge and nutritional understanding about the generalizability and contextualization of diet knowledge.
  • Niemi, Milla (Helsingin yliopisto, 2016)
    Road networks and traffic cause worldwide environmental and ecological problems, and collisions with large animals are an increasing traffic safety issue. There is thus a continuous need to improve our understanding of the factors affecting the controversial relationship between nature, traffic, and human welfare, and to develop efficient mitigation measures. In this thesis, I found that population size is the most important factor explaining the yearly variation in the number of moose-vehicle collisions (MVCs) in Finland. The monthly number of MVCs peaked in autumn with a secondary peak in early summer. This pattern differed from Sweden and Norway where the peak occurred in winter. In contrast, the relative risk of personal injuries was highest during summer in each country. Spring weather was found to affect the detailed timing of spring MVCs in Finland: collisions occurred earlier during warm springs. In addition, as the beginning of the growing season has moved to an earlier date in the last two decades, so has the spring MVC peak. In addition to MVCs, several thousand collisions involving deer species other than moose annually occur on Finnish roads. White-tailed deer was found to suffer highest traffic mortality rates in relation to population size, followed by moose, roe deer, and fallow deer. Among the studied species, moose has the largest and roe deer the smallest probability of surviving a collision. The adverse impacts of traffic on animals could be mitigated for example by constructing wildlife passages. Dry paths under road bridges proved to be an effective mitigation measure for reducing the traffic mortality of small and medium-sized terrestrial animals. The results of this thesis underline that different mitigation measures from population management and driver education to structural solutions are needed when trying to reduce the number and consequences of animal-vehicle collisions.
  • Help-Rinta-Rahko, Hanna (Helsingin yliopisto, 2016)
    The interaction of auxin and cytokinin signalling regulates primary root procambial patterning, xylem cell fate and differentiation in Arabidopsis thaliana. Plants contribute to the Earth s atmosphere by binding carbon dioxide and releasing oxygen. Trees produce biomass, which is a renewable source of energy. The Arabidopsis root vasculature is a good model system for studying biomass formation, as it contains the same cell types that are also found in trees: xylem, phloem and intervening pluripotent procambial cells. In Arabidopsis thaliana roots, these cells arise from stem cells within the root meristem. The wild type root radial pattern is bisymmetric, and the regulation of xylem formation is controlled by phytohormones, especially auxin and cytokinin. Our findings show that the vascular pattern is set by a symmetry-breaking event during embryogenesis and is initiated by auxin accumulation and signalling at the cotyledon initials. As the embryo grows, the high auxin signalling promotes the expression of AHP6. Upregulation of AHP6 in specific cells leads to inhibition of cytokinin signalling and might be a key factor in symmetry breakage. Mutants with altered cotyledon numbers or altered cotyledon anatomy fail to establish the bisymmetric pattern and often show altered root symmetry. In growing roots, the bisymmetric pattern is actively reinforced by polar auxin transport and long distance cytokinin transport/translocation from the apical parts of the plant. Cytokinin movement via the phloem and unloading at the root apical meristem promotes cytokinin signalling in the procambial cells in the proximal meristem. Both cytokinin and auxin are required during root procambial patterning, and the interaction of these two phytohormones is mutually inhibitory. According to our model (described in the first part of this thesis), auxin signalling is critical for protoxylem identity formation. In turn, the results from the procambial re-patterning experiments (second part of this thesis) show that cytokinin is the key hormone in promoting cell proliferation in the proximal meristem. Epistasis experiments illustrate that a fine balance between these two hormones affects the fate of all vascular cells. We are beginning to understand the complexity and interdependencies of signalling pathway interactions during proximal meristem vascular patterning, yet the temporal aspect is still largely unexplored. In the last part of this thesis, I discuss the role ROS signalling might have in stele patterning and temporal regulation of programmed cell death. While our published GRI-MC9-PRK5 module might not be directly linked to primary root proximal meristem procambial patterning, one cannot exclude the possibility that it might be required in the final stages of protoxylem differentiation or that a similar signalling mechanism could regulate initial stele patterning and meristem growth dynamics. This thesis describes the auxin-cytokinin interaction in vascular initial patterning and the mechanism by which the hormonal signalling domains are maintained in the proximal meristem. The unpublished data demonstrate how procambial cells can be manipulated to generate new tissues by affecting the homeostasis of auxin and cytokinin signalling. The last part of the thesis describes a cell death signalling module and speculates that it (or similar module) might be involved with primary root meristem maturation.