Browsing by Issue Date

Sort by: Order: Results:

Now showing items 1-20 of 41
  • Ala-Poikela, Marjo (Helsingin yliopisto, 2014)
    Potyviruses (genus Potyvirus, family Potyviridae) are plant RNA viruses infecting a broad range of agriculturally important crops. Potyviruses have compact genomes encoding a small number of proteins and are therefore dependent on host factors. Even though several host factors are indispensable for plant virus infection, most so far identified natural recessive resistance genes to different potyviruses are homologs of the same genes, translation initiation factor 4E (eIF4E) and its plant-specific isoform eIF(iso)4E. The eIF4E is best known for recruiting ribosomes to capped mRNAs during cap-dependent translation. The viral-genome linked protein (VPg) encoded by potyviruses have been reported to interact with eIF4E/eIF(iso)4E. The hypothesis is that VPg substitutes for the cap-structure by binding to the eIF4E and hereby hijacks and assembles the host cell translation machinery for viral translation that subsequently inhibits host translation. However, the exact roles of eIF4E/eIF(iso)4E in recessive resistance against potyviruses are still cryptic. In this study we present novel data that will give new insights into the molecular mechanisms behind eIF4E-mediated resistance against potyviruses. In this study, we demonstrated that helper component proteinase (HCpro) from Potato virus A (PVA), Potato virus Y (PVY), and Tobacco etch virus (TEV) interacted with the eIF(iso)4E and eIF4E of tobacco (Nicotiana tabacum) and potato (Solanum tuberosum). An eIF4E-binding motif was found in the C-terminal region of HCpro and point mutations within the motif debilitated interactions of HCpro with translation initiation factors and impeded PVA virulence in plants. In PVA-infected cells, interactions between HCpro and eIF(iso)4E were confined to round-shaped structures that associated with the 6 kilodalton protein 2 (6K2)-induced viral replication vesicles. Furthermore an eIF4E-binding motif was recognized in the VPg of PVA and two other potyviruses. Mutations in the eIF4E-binding motif interfered with interactions of VPg with eIF4E, impaired suppression of RNAi by VPg, and abolished virulence of PVA. These results show that the interaction of VPg with eIF4E controlled by the eIF4E-binding motif in VPg is essential for PVA virulence, regardless of that VPg still binds to the cap-binding domain of eIF4E. The capability to bind to two distinct binding sites of eIF4E might reflect two distinct functions of VPg. HCpro and VPg were found to interact with each other in the nucleus and nucleolus in PVA-infected cells. In cytoplasm, the VPg-HCpro interaction was observed in round-shaped bodies in the proximity of the nucleus and chloroplasts, but not in association with the 6K2-induced replication vesicles. The interactions of VPg with eIF4E via the eIF4E-binding domain may also regulate interactions of HCpro with eIF4E. Taken together, the results suggest novel mechanisms by which potyviruses interact with the host translation system and other putative functions involving eIF4E/eIFiso4E.
  • Petty, Aaron (2014)
    The production of energy wood from small-diameter (DBH < 9 cm) forests in Finland through separate energy wood and integrated energy wood and pulpwood production often face cost pressures that inhibit economic viability of many operations. Systemic factors, such as small stem sizes, limited removals, and high density of young forest stands limit the efficiency of many operations resulting in low productivity and high operating costs, particularly within cutting operations. Within the study, means to increase efficiency and mitigate costs of small-diameter energy wood and integrated energy wood and pulpwood operations by identifying optimal methods, technologies, and policy that may be applied were investigated. Studies of integrated and delimbed stemwood cutting methods including the use of multi-tree handling and combined timber assortments in forest stands with stem size (DBH) of removals varying between 5-17 cm were investigated and compared against separate pulpwood production. Findings suggest that the methods provide increases in productivity and decreases in costs, particularly in < 11 cm DBH conditions. Crane scale measuring was investigated as a technical solution in timber logistics to be applied in energy wood and industrial roundwood procurement. The measuring method, used as a basis of payment, was found to provide a reliable, accurate, and cost effective method when compared with a manual timber pile measurement system. Policies, in the form of financial incentives were investigated to determine the effects of applicable subsidies on the profitability of energy wood production based on stem size of removal, finding possibilities for profitable operations with reduction in subsidies, however, with stem sizes (DBH) of removal ≤ 7 cm incentives played an important role in increasing profitability. Cost reductions were identified through: The utilization of integrated and delimbed stemwood harvesting methods with multi-tree handling, decreasing harvesting costs by 0.1-52.4% dependent on stem size (DBH) of removal between 7-17 cm when compared to a traditional pulpwood harvesting method; Combining timber assortments providing harvesting cost reductions between 1.5-8.0% between 5-17 cm; Crane scale measurement use provided increased accuracy and a 18.2-45.5% reduction in costs when compared to a manual timber pile measurement system when dependent on estimated working volumes between 20,000-30,000 cubic meters; Financial incentives under the PETU system were applied increasing profit margins of integrated supply chain operations by 14.3-19.9% dependent on stem size of removal, particularly with stem size of removals between 5-7 cm. Through rationalization of supply chains, harvesting methods, technologies, and policy which exhibit the ability to reduce costs should be utilized throughout the whole supply chain where implementation is possible. Keywords: Energy wood production, integrated forest operations, supply chain profitability, productivity, small-diameter forest stands, subsidies, crane scale measurement.
  • Laurila, Jussi (2013)
    The aim of this thesis was to improve the quality of energy wood and therefore increase the potential of forest energy. About half of the mass of a freshly-felled tree consists of water. From the point of view of energy generation this water is unwelcome. There are two main ways to dry energy wood; these are artificial drying and drying naturally. The Norway spruce (Picea abies L. Karst.) stump wood dries fairly quickly in favourable natural conditions. The average moisture content (wet basis) of a stump was about 31 % one month after stump harvesting. Small-sized whole trees did not dry well at roadside storage sites under natural conditions. About one year after harvesting the moisture content of a small-sized whole tree was still about 43 %. However, during storing a remarkable weight loss of 37 % was detected between the forest and the heating plant. The most effective and the fastest drying method found in this study was the continuous compression drying method. The lowest moisture content of 30 % was achieved for Downy birch (Betula pubescens Ehrh.) by continuous pressing using 38 MPa and with a pressing time of 30 seconds. The energy consumption for compression drying is very low compared to the energy required to vaporise water in thermal drying. The techno-economic forest energy potential of the study area was 1.6 TWh/y. The forest energy potential calculations were made using the heating value of fresh wood and therefore the real potential will be greater when using dried energy wood. For absolutely dry wood the potential was about 1.9 TWh/y. The properties of energy wood vary widely depending on its assortment, storage conditions, as well as the weather conditions and the origin of the energy wood. However, a better understanding of energy wood properties will increase forest energy s potential and the use of renewable energy and thus help mitigate climate change globally.
  • Kallioniemi, Marja (MTT eli Maa- ja elintarviketalouden tutkimuskeskus, Taloustutkimus, 2013)
    The restructuring of agriculture in Finland has resulted in several types of change on farms during recent years. The field areas and sizes of herds per farm have been increasing, while the number of farms has been decreasing. Concurrently, the risks of agriculture have increased. Ongoing change has been described as a modernization process from traditional farming towards a more enterprise form of agriculture. Farms are mainly owned by private persons in Finland. The farm entrepreneurs and their well-being at work are at the core of this thesis. Human capacity, including work ability, health and coping has been assessed as a crucial element for the success of the farm enterprise. Stress is commonly described as a situation in which the demands of work are greater than the worker is able to cope with. This type of conflicting and strenuous situation may induce different kinds of symptoms and diseases in people. Agriculture is among the most injury-prone working sectors. The aims of this research were to determine the prevalence and symptoms of stress among full-time farm entrepreneurs, identify possibilities to increase occupational safety during animal handling work and characterise the negative and positive elements of women s working conditions on dairy farms. These aims were addressed through two main samples. The first was a telephone survey of 1 182 full-time farmers focusing on stress and symptoms among the respondents. Secondly, a qualitative study was carried out involving ten female farmers working on dairy farms that focused on occupational safety during animal handling and the working conditions of women. According to the results, full-time farmers experienced less stress than among the general working population in Finland. One in four (26%) full-time farmers had symptoms of weakness or fatigue and one in five (19%) farmers had symptoms of insomnia or difficulties in falling asleep. Both of these symptoms had increased statistically significantly when compared to an earlier follow-up survey in 1992. Problems with social relationships and lowered state of health were associated with stress and symptoms. Pesticide usage of over two weeks during the previous growing period had an association with symptoms. Based on the literature review, the most common stressors among farm entrepreneurs were the farm economy, regulations, the weather, dangers in farm work and new legislation. In the qualitative study occupational accidents were frequent: nearly all women had suffered one or more injuries during the previous two years. Unexpected animal behavior was considered as the most significant injury risk.The results revealed that a positive relationship between the stockperson and cattle as well as knowledge of animal behaviour and welfare enabled a safer working environment to gradually be built in the cattle barn. In practice, the stockperson should keep physical conditions animal friendly, perform positive and predictable routines, habituate young calves to people, avoid the separation of an individual animal, not dominate animals by force and be patient during work among farm animals. In addition, it is important to always be prepared for self-defence. Female respondents were involved in wide range of different work tasks on dairy farms. As a positive element, nearly all respondents considered work with animals and close to nature to be rewarding. On the other side, women s working days were long. Old traditions may create invisible barriers to organizing the work in a more functional way on enlarged farm units. Most women chose farm entrepreneur as their professional title, but their professional position was often undefined or misunderstood. The valuable contribution of female farm entrepreneurs to agriculture should be recognized and supported, because women s expertise within agriculture is important in finding solutions for future challenges such as sustainable, organic agriculture and animal welfare. Due to the ongoing restructuring of the agricultural sector in Finland, the well-being at work among farm entrepreneurs requires support, efforts and attention. The working environment related to agriculture includes several risks such as stress, injury and an impairment of work ability.
  • Heikkilä, Anna-Maija (MTT Agrifood Research Finland, 2013)
    The objective of this thesis was to find expedients that would improve the economic performance of Finnish dairy farms. Means under examination were replacement decisions related to technology and herds. The theory of optimal behavior formed the basis for the methods used in solving the research problems. Empirical data originated from the Farm Accountancy Data Network (FADN) and from the Finnish dairy herd recording system. When studying the sustainability of herds, the replacement of a dairy cow was investigated by applying dynamic programming. The optimal replacement rules were almost similar for healthy and diseased cows indicating that the treatment of diseases is more profitable than replacing a diseased cow with a first-lactating one. Only cows with low milk production capacity should be disposed intentionally. A linear programming model was built for examining the optimal choices between conventional insemination, insemination with sex-sorted sperm and the use of conventional or sex-selected embryo transfer in a herd. The optimal outcome was a mixture of available technologies. Sex-sorted sperm was recommended for heifers only and primarily for calf production. In practice, the optimal insemination strategy is herd-specific. When studying the adoption of novel technology, discrete technology choice models were utilized. The results suggested that investment allowances significantly affect the changeover to loose-housing technology and robotic milking. Total factor productivity growth increased on those farms that switched from a conventional to an automatic milking system. The growth rate was derived from technology-specific production functions estimated with a two-stage estimation method. This method catered for the sample selection bias caused by the endogenous technology choice. The adoption of robotic milking intensified the positive development linked to overall improvements in production technology and an expansion in herd size given that milk production matched the capacity of the robot. In conclusion, by prolonging the herd life of dairy cows, dairy farmers can improve the economic performance of milk production. Therefore, farmers' awareness about the real costs of premature culling and the gains that can be achieved by treating a diseased cow must be improved. Optimizing tools, based on farm-specific input data, should be developed for determining the optimal replacement decisions and, hence, the optimal reproduction policy. Investment allowances are needed to boost up investments on those farms which have potential to develop their production to meet the future challenges. Investments in technology appropriate for large farms improve productivity growth and, thus, the prospects of dairy farms to survive in the long run. However, a human cannot be replaced by technology, not even by novel technology.
  • Niskanen, Anna-Maija (Finnish Society of Forest Science, Finnish Forest Research Institute, Faculty of Agriculture and Forestry of the University of Helsinki, School of Forest Sciences of the University of Eastern Finland, 2013)
    The aim of this study is to assess the clonal variation in Scots pine (Pinus sylvestris L.) clones and in transgenic lines of silver birch (Betula pendula Roth) and its causes, with special attention to the effects of cloning and transgenesis in tree breeding programmes. The parental effect on cloning success variation was studied in an experiment where Scots pine embryogenic lines were initiated from immature seeds of a full diallele cross. The evaluation was made after culture initiation, on maintenance medium and by mature embryo production. Growth and stem straightness of Scots pine clones were assessed in a 10-year field trial established with rooted cuttings. The effect of a single gene transfer, the sugar beet chitinase IV gene (chiIV), was assessed on plant growth, susceptibility to fungal diseases and development of root associated fungal communities and phenology, in a 3-year field trial established with micropropagated transgenic silver birch lines and wild-type clones. The results of the somatic embryogenesis experiment with Scots pine showed that the initiation success, as well as maturation, was more affected by the genotype of the mother than the one of the father, while during the proliferation period the mother s effect decreased and the father s increased. The field trial with Scots pine showed that the tree s genotype, more than the propagation method, has an effect on the plant behaviour in the field. In silver birch transgenic lines, the introduction of a single gene (chiIV) led to a reduction in growth and quality characteristics, although no significant changes occurred regarding fungal disease resistance, ectomycorrhizal colonization or fungal community structure, as compared to the natural variation occurring in wild type clones. The conclusion was that the variation in the success of Scots pine embryogenesis and in the growth of rooted cuttings is strongly affected by genotype and, hence, the rooted cuttings are suitable for testing height growth in breeding programmes. A single chiIV gene transfer did not improve significantly fungal disease resistance in silver birch or interfere with root associated fungal community. However, the variation in adaptive traits among silver birch transgenic lines is at the same level with the variation detected in randomly selected wild-type silver birches and single transgenic lines may be selected in breeding programmes.
  • Omoro, Loice M A (2012)
    Although forest ecosystems are crucial for human survival they are constantly under threat from human interventions and natural disasters which reduce their capacities to effectively provide ecosystem services. As populations increase, incidences of forest encroachments become frequent to affect the provision of the services. The objective in this study was to assess some ecosystem benefits and to determine how the local communities used and value them. The benefits assessed were floristic diversity; biomass and soil organic carbon densities; and suitability of indigenous tree species for forest rehabilitation based on soil properties in four different forest types, indigenous and plantations of cypress, eucalypt and pine in Taita Hills, Kenya. The perceptions of local community regarding how they use and value these benefits were also assessed. The conceptual framework was based on the Millennium Ecosystem Assessment. Sampling design was based on a US Forest Service model used in the indigenous forests. For each forest area and forest type, a minimum of four plots were randomly selected and a total of 77 plots from 38 groups were sampled. In each plot, all juvenile trees of 5 cm or more in diameter at breast height were sampled for floristic diversity, biomass carbon stock and vegetation-soil relationship assessments. Soils were sampled at, 0-20 and 20-50 cm, for chemical and physical analyses to determine the soil organic carbon densities and vegetation-soil relationships. Tree species diversity, carbon densities derived from biomass and soil data were analyzed quantitatively. A qualitative analysis was done for the socio-economic part of the study, from data obtained using selected participatory rural appraisal tools and semi-structured questionnaires. Biodiversity analyses were accomplished using the Shannon-Weaver s Index. to assess the tree species composition. Tree biomass was estimated from allometric functions developed for tropical forests while soil organic carbon stocks were computed as a product of the analyzed carbon contents and bulk density values estimated using a pedotransfer function and measured particle size. Soil-vegetation relationships were determined by Principal Component Analysis, using CANOCO 4.5 software. The statistical analyses were accomplished by use of three versions of SPSS software for Windows (15, 16 and 20). The study established that indigenous forest was more diverse than plantations and regeneration of indigenous species significantly higher in exotic plantations of the most disturbed area than in the less disturbed areas. Some indigenous species correlated with sodium, phosphorus, carbon, pH and soil texture while some had no correlation with soil variables. Factors unrelated to soil variables, namely gaps were found to be important for the emergence and early establishment of seedlings. Total biomass C densities were generally higher in indigenous forest than in some exotic plantations, especially the cypress. Indigenous forest also had higher soil carbon stocks than plantations of exotic species. Community survey showed perceptions that exotics plantations contributed reductions of the forests to provide water and medicinal plants. Therefore, they are motivated to rehabilitate the forest by planting indigenous tree species. This study concluded that indigenous forest valuable for ecosystem services and that soil-vegetation relationships established be utilized along with soil analyses to select indigenous species to be planted in certain areas for rehabilitation. Such rehabilitation will enhance the floristic diversity and carbon sequestration and storage and therefore, contribute to restoration of the ecosystem services. Therefore, the initiated reforestation exercises with indigenous tree species to replace the exotic tree species are well justified. Key Words: Floristic diversity, biomass, carbon stocks, plantation, indigenous forest, Principal Component Analysis
  • Li, Ning (Finnish Society of Forest Science, Finnish Forest Research Institute, Faculty of Agriculture and Forestry of the University of Helsinki, School of Forest Sciences of the University of Eastern Finland, 2012)
    Growing interest in corporate sustainability has translated into growing concerns about how corporate responsibility management can be more effectively integrated with economic business goals, challenging organizations to shift their priorities toward more holistic strategies and performance assessment models which encompass measures related to both multiple stakeholders and responsibilities. Although interactions between corporate (social) strategy, sustainability performance, and business competitiveness have received considerable attention in both theory and practice over the past three decades, the phenomenon is under-investigated in forest-based industry, which is undergoing broad structural changes and global shifts in market demand and supply. This dissertation aims to fill this gap by approaching it from the resource-based view of the firm and empirically investigating a variety of aspects in an attempt to provide an overview of state-of-the-art corporate sustainability in global forest-based industry and to capture a structured view of the relationships between sustainability performance, competitiveness and economic performance among forest-based companies. The results indicate that both larger and small forest-based companies seem to have clear stakeholder orientations. Driven by legal requirements aspects, small companies tend to adopt informal corporate responsibility strategies and tools to meet their stakeholder expectations. A majority of large forest industry companies appear to have implemented corporate responsibility mainly with a profit-maximizing assumption and a relatively defensive approach parallel to and beyond their core business. To these large companies, environmental and economic issues are dominant in disclosure and profitability, while regional differences are not decisive in formulating strategies for sustainability reporting. Furthermore, the results bolster previous findings that have reported a positive return on corporate responsibility initiatives in terms of profitability, suggesting that corporate responsibility can enhance value creation for forest-based companies. To that end, a differentiated business-oriented approach is necessary in managing the business case for sustainability.
  • Toivonen, Ritva (Suomen Metsätieteellinen Seura ry, 2011)
    The research analyzes product quality from a customer perspective in the case of the wood products industry. Of specific interest is to understand better how environmental quality is perceived from a customer perspective. The empirical material used comprises four data-sets from Finland, Germany and the UK, collected during 1992 2004. The methods consist of a set of quantitative statistical analyses. The results indicate that perceived quality from a customer perspective can be presented using a multidimensional and hierarchical construct with tangible and intangible dimensions, that is common to different markets and products. This applies in the case of wood products but also more generally at least for some other construction materials. For wood products, tangible product quality has two main sub-dimensions: technical quality and appearance. For product intangibles, a few main quality dimensions seem be detectable: Quality of intangibles related to the physical product, such as environmental issues and product-related information, supplier-related characteristics, and service and sales personnel behavior. Environmental quality and information are often perceived as being inter-related. Technical performance and appearance are the most important considerations for customers in the case of wood products. Organizational customers in particular also clearly consider certain intangible quality dimensions to be important, such as service and supplier reliability. The high technical quality may be considered as a license to operate , but product appearance and intangible quality provide potential for differentiation for attracting certain market segments. Intangible quality issues are those where Nordic suppliers underperform in comparison to their Central-European competitors on the important German markets. Environmental quality may not have been used to its full extent to attract customers. One possibility is to increase the availability of the environment-related information, or to develop environment-related product characteristics to also provide some individual benefits. Information technology provides clear potential to facilitate information-based quality improvements, which was clearly recognized by Finnish forest industry already in the early 1990s. The results indeed indicate that wood products markets are segmented with regard to quality demands
  • Wermundsen, Terhi (2010)
    Knowledge of the habitat requirements of bat species is needed in decision making in land use planning. Bats' hibernation requirements were studied both in Estonia and in southern Finland. In both countries, the northern bat and the brown long-eared bat hibernated in colder and drier locations, whereas Daubenton's bat and Brandt's/whiskered bats hibernated in warmer and more humid locations. In Estonia, the pond bat hibernated in the warmest and most humid conditions, whereas Natterer's bat hibernated in the coldest and driest conditions. Hibernacula were at their coldest in mid-season and became warmer towards the end of the season. The results suggest that bats made an active choice of colder hibernation temperatures at the seasons end. They minimised the negative effects of hibernation early in the hibernation season by hibernating in warmer locations and energy expenditure late in the hibernation season by hibernating in colder locations. The use of foraging habitats was studied in northern and southern Finland. The northern bat used foraging sites opportunistically. Daubenton's bat foraged mainly in water habitats, whereas Brandt's/whiskered bats and the brown long-eared bat foraged mainly in forest habitats. In northern Finland, Daubenton's bats foraged almost exclusively on rivers and typically together with the northern bat. Daubenton's bats and Brandt's/whiskered bats were found only where there were lower ambient light levels. One of the most important things in the management of foraging areas for them is to keep them shady. Hibernacula in Finland typically housed few bats, suggesting that hibernation sites used by even a small number of bats are important. Bats typically used natural stone for hibernation suggesting that natural underground sites in rocks or cliffs or man-made underground sites built using natural stone are important for them. The results suggest that appropriate timing of surveys may vary according to the species and latitude.
  • Hiltunen, Lea (2010)
    Tieteellinen tiivistelmä Common scab is one of the most important soil-borne diseases of potato (Solanum tuberosum L.) in many potato production areas. It is caused by a number of Streptomyces species, in Finland the causal agents are Streptomyces scabies (Thaxter) Lambert & Loria and S. turgidiscabies Takeuchi. The scab-causing Streptomyces spp. are well-adapted, successful plant pathogens that survive in soil also as saprophytes. Control of these pathogens has proved to be difficult. Most of the methods used to manage potato common scab are aimed at controlling S. scabies, the most common of the scab-causing pathogens. The studies in this thesis investigated S. scabies and S. turgidiscabies as causal organisms of common scab and explored new approaches for control of common scab that would be effective against both species. S. scabies and S. turgidiscabies are known to co-occur in the same fields and in the same tuber lesions in Finland. The present study showed that both these pathogens cause similar symptoms on potato tubers, and the types of symptoms varied depending on cultivar rather than the pathogen species. Pathogenic strains of S. turgidiscabies were antagonistic to S. scabies in vitro indicating that these two species may be competing for the same ecological niche. In addition, strains of S. turgidiscabies were highly virulent in potato and they tolerated lower pH than those of S. scabies. Taken together these results suggest that S. turgidiscabies has become a major problem in potato production in Finland. The bacterial phytotoxins, thaxtomins, are produced by the scab-causing Streptomyces spp. and are essential for the induction of scab symptoms. In this study, thaxtomins were produced in vitro and four thaxtomin compounds isolated and characterized. All four thaxtomins induced similar symptoms of reduced root and shoot growth, root swelling or necrosis on micro-propagated potato seedlings. The main phytotoxin, thaxtomin A, was used as a selective agent in a bioassay in vitro to screen F1 potato progeny from a single cross. Tolerance to thaxtomin A in vitro and scab resistance in the field were correlated indicating that the in vitro bioassay could be used in the early stages of a resistance breeding program to discard scab-susceptible genotypes and elevate the overall levels of common scab resistance in potato breeding populations. The potential for biological control of S. scabies and S. turgidiscabies using a non-pathogenic Streptomyces strain (346) isolated from a scab lesion and S. griseoviridis strain (K61) from a commercially available biocontrol product was studied. Both strains showed antagonistic activity against S. scabies and S. turgidiscabies in vitro and suppressed the development of common scab disease caused by S. turgidiscabies in the glasshouse. Furthermore, strain 346 reduced the incidence of S. turgidiscabies in scab lesions on potato tubers in the field. These results demonstrated for the first time the potential for biological control of S. turgidiscabies in the glasshouse and under field conditions and may be applied to enhance control of common scab in the future.
  • Iho, Antti (MTT, 2010)
    Phosphorus is a nutrient needed in crop production. While boosting crop yields it may also accelerate eutrophication in the surface waters receiving the phosphorus runoff. The privately optimal level of phosphorus use is determined by the input and output prices, and the crop response to phosphorus. Socially optimal use also takes into account the impact of phosphorus runoff on water quality. Increased eutrophication decreases the economic value of surface waters by Deteriorating fish stocks, curtailing the potential for recreational activities and by increasing the probabilities of mass algae blooms. In this dissertation, the optimal use of phosphorus is modelled as a dynamic optimization problem. The potentially plant available phosphorus accumulated in soil is treated as a dynamic state variable, the control variable being the annual phosphorus fertilization. For crop response to phosphorus, the state variable is more important than the annual fertilization. The level of this state variable is also a key determinant of the runoff of dissolved, reactive phosphorus. Also the loss of particulate phosphorus due to erosion is considered in the thesis, as well as its mitigation by constructing vegetative buffers. The dynamic model is applied for crop production on clay soils. At the steady state, the analysis focuses on the effects of prices, damage parameterization, discount rate and soil phosphorus carryover capacity on optimal steady state phosphorus use. The economic instruments needed to sustain the social optimum are also analyzed. According to the results the economic incentives should be conditioned on soil phosphorus values directly, rather than on annual phosphorus applications. The results also emphasize the substantial effects the differences in varying discount rates of the farmer and the social planner have on optimal instruments. The thesis analyzes the optimal soil phosphorus paths from its alternative initial levels. It also examines how erosion susceptibility of a parcel affects these optimal paths. The results underline the significance of the prevailing soil phosphorus status on optimal fertilization levels. With very high initial soil phosphorus levels, both the privately and socially optimal phosphorus application levels are close to zero as the state variable is driven towards its steady state. The soil phosphorus processes are slow. Therefore, depleting high phosphorus soils may take decades. The thesis also presents a methodologically interesting phenomenon in problems of maximizing the flow of discounted payoffs. When both the benefits and damages are related to the same state variable, the steady state solution may have an interesting property, under very general conditions: The tail of the payoffs of the privately optimal path as well as the steady state may provide a higher social welfare than the respective tail of the socially optimal path. The result is formalized and an applied to the created framework of optimal phosphorus use.
  • Primmer, Eeva (Finnish Society of Forest Science, Finnish Forest Research Institute, University of Helsinki, and University of Eastern Finland, 2010)
    Integrating biodiversity conservation into forest management in non-industrial private forests requires changes in the practices of those public and private actors that have implementing responsibilities and whose strategic and operational opportunities are at stake. Understanding this kind of context-dependent institutional adaptation requires bridging between two analytical approaches: policy implementation and organizational adaptation, backed up with empirical analysis. The empirical analyses recapitulated in this thesis summary address organizational competences, specialization, professional judgment, and organizational networks. The analyses utilize qualitative and quantitative data from public and private sector organizations as well as associations. The empirical analyses produced stronger signals of policy implementation than of organizational adaptation. The organizations recognized the policy and social demand for integrating biodiversity conservation into forest management and their professionals were in favor of conserving biodiversity. However, conservation was integrated to forest management so tightly that it could be said to be subsumed by mainstream forestry. The organizations had developed some competences for conservation but the competences did not differentiate among the organizations other than illustrating the functional differences between industry, administration and associations. The networks that organizations depended on consisted of traditional forestry actors and peers both in planning policy and at the operational level. The results show that he demand for biodiversity conservation has triggered incremental changes in organizations. They can be considered inert regarding this challenge. Isomorphism is advanced by hierarchical guidance and standardization, and by professional norms. Analytically, this thesis contributes to the understanding of organizational behavior across the public and private sector boundaries. The combination of a policy implementation approach inherent in analysis of public policies in hierarchical administration settings, and organizational adaptation typically applied to private sector organizations, highlights the importance of institutional interpretation. Institutional interpretation serves the understanding of the empirically identified diversions from the basic tenets of the two approaches. Attention to institutions allows identification of the overlap of the traditionally segregated approaches.
  • Havimo, Mikko (Suomen metsätieteellinen seura, 2010)
    Printing papers have been the main product of the Finnish paper industry. To improve properties and economy of printing papers, controlling of tracheid cross-sectional dimensions and wood viscoelasticity are examined in this study. Controlling is understood as any procedure which yields raw material classes with distinct properties and small internal variation. Tracheid cross-sectional dimensions, i.e., cell wall thickness and radial and tangential diameters can be controlled with methods such as sorting wood into pulpwood and sawmill chips, sorting of logs according to tree social status and fractionation of fibres. These control methods were analysed in this study with simulations, which were based on measured tracheid cross-sectional dimensions. A SilviScan device was used to measure the data set from five Norway spruce (Picea abies) and five Scots pine (Pinus sylvestris) trunks. The simulation results indicate that the sawmill chips and top pulpwood assortments have quite similar cross-sectional dimensions. Norway spruce and Scots pine are on average also relatively similar in their cross-sectional dimensions. The distributions of these species are somewhat different, but from a practical point of view, the differences are probably of minor importance. The controlling of tracheid cross-sectional dimensions can be done most efficiently with methods that can separate fibres into earlywood and latewood. Sorting of logs or partitioning of logs into juvenile and mature wood were markedly less efficient control methods than fractionation of fibres. Wood viscoelasticity affects energy consumption in mechanical pulping, and is thus an interesting control target when improving energy efficiency of the process. A literature study was made to evaluate the possibility of using viscoelasticity in controlling. The study indicates that there is considerable variation in viscoelastic properties within tree species, but unfortunately, the viscoelastic properties of important raw material lots such as top pulpwood or sawmill chips are not known. Viscoelastic properties of wood depend mainly on lignin, but also on microfibrillar angle, width of cellulose crystals and tracheid cross-sectional dimensions.
  • Karhu, Kristiina (The Finnish Society of Forest Science, Finnish Forest Research Institute, Faculty of Agriculture and Forestry of the University of Helsinki and Faculty of Science and Forestry of the University of Eastern Finland, 2010)
    The temperature sensitivity of decomposition of different soil organic matter (SOM) fractions was studied with laboratory incubations using 13C and 14C isotopes to differentiate between SOM of different age. The quality of SOM and the functionality and composition of microbial communities in soils formed under different climatic conditions were also studied. Transferring of organic layers from a colder to a warmer climate was used to assess how changing climate, litter input and soil biology will affect soil respiration and its temperature sensitivity. Together, these studies gave a consistent picture on how warming climate will affect the decomposition of different SOM fractions in Finnish forest soils: the most labile C was least temperature sensitive, indicating that it is utilized irrespective of temperature. The decomposition of intermediate C, with mean residence times from some years to decades, was found to be highly temperature sensitive. Even older, centennially cycling C was again less temperature sensitive, indicating that different stabilizing mechanisms were limiting its decomposition even at higher temperatures. Because the highly temperature sensitive, decadally cycling C, forms a major part of SOM stock in the organic layers of the studied forest soils, these results mean that these soils could lose more carbon during the coming years and decades than estimated earlier. SOM decomposition in boreal forest soils is likely to increase more in response to climate warming, compared to temperate or tropical soils, also because the Q10 is temperature dependent. In the northern soils the warming will occur at a lower temperature range, where Q10 is higher, and a similar increase in temperature causes a higher relative increase in respiration rates. The Q10 at low temperatures was found to be inversely related to SOM quality. At higher temperatures respiration was increasingly limited by low substrate availability.
  • Cao, Tianjian (Finnish Society of Forest Science, Finnish Forest Research Institute, Faculty of Agriculture and Forestry of the University of Helsinki, Faculty of Forest Sciences of the University of Joensuu, 2010)
    Forest management is facing new challenges under climate change. By adjusting thinning regimes, conventional forest management can be adapted to various objectives of utilization of forest resources, such as wood quality, forest bioenergy, and carbon sequestration. This thesis aims to develop and apply a simulation-optimization system as a tool for an interdisciplinary understanding of the interactions between wood science, forest ecology, and forest economics. In this thesis, the OptiFor software was developed for forest resources management. The OptiFor simulation-optimization system integrated the process-based growth model PipeQual, wood quality models, biomass production and carbon emission models, as well as energy wood and commercial logging models into a single optimization model. Osyczka s direct and random search algorithm was employed to identify optimal values for a set of decision variables. The numerical studies in this thesis broadened our current knowledge and understanding of the relationships between wood science, forest ecology, and forest economics. The results for timber production show that optimal thinning regimes depend on site quality and initial stand characteristics. Taking wood properties into account, our results show that increasing the intensity of thinning resulted in lower wood density and shorter fibers. The addition of nutrients accelerated volume growth, but lowered wood quality for Norway spruce. Integrating energy wood harvesting into conventional forest management showed that conventional forest management without energy wood harvesting was still superior in sparse stands of Scots pine. Energy wood from pre-commercial thinning turned out to be optimal for dense stands. When carbon balance is taken into account, our results show that changing carbon assessment methods leads to very different optimal thinning regimes and average carbon stocks. Raising the carbon price resulted in longer rotations and a higher mean annual increment, as well as a significantly higher average carbon stock over the rotation.
  • Jalli, Marja (2010)
    In Finland, barley, Hordeum vulgare L., covers 50 % of the total acreage devoted to cereal cultivation. The most common disease of barley in Finland is net blotch, a foliar disease caused by the ascomycete Pyrenophora teres Drechsler. Disease resistance based on plant genes is an environmentally friendly and economical way to manage plant diseases caused by biotic stresses. Development of a disease resistance breeding programme is dependent on knowledge of the pathogen. In addition to information on the epidemiology and virulence of a pathogen, knowledge on how the pathogen evolves and the nature of the risks that might arise in the future are essential issues that need to be taken into account to achieve the final breeding aims. The main objectives of this study were to establish reliable and efficient testing methods for Pyrenophora teres f. teres virulence screening, and to understand the role of virulence of P. teres f. teres in Finland from a disease resistance breeding point of view. The virulence of P. teres was studied by testing 239 Finnish P. teres f. teres isolates collected between 1994 2007 originating from 19 locations, and 200 P. teres progeny isolates originating from artificially produced P. teres matings. According to the results of this study, screening for P. teres f. teres isolates on barley seedlings under greenhouse conditions is a feasible and cost efficient method to describe the virulence spectrum of the pathogen. Inoculum concentration and the seedling leaf used to gauge virulence had significant effects. Barley grain size, morphological traits of P. teres isolates, spore production and growth rate on agar did not affect the expression of virulence. A common barley differential set to characterize the P. teres virulence was developed and is recommended to be used globally. The virulence spectrum of Finnish P. teres f. teres isolates collected in 1994-2007 was constant both within and between the years. The results indicated differences in the pathogen s aggressiveness and in barley genotypes resistance. However, differences in virulence were rarely significant. Unlike in laboratory conditions, no indications of changes in virulence caused by the sexual reproduction have been observed in Finnish barley fields. In Finland, durable net blotch resistance has been achieved by introducing resistance from other barley varieties using traditional crossing methods, including wide crossing, and testing the breeding material at early generations at several sites under natural infection pressure. Novel resistance is available, which is recommended to minimize the risk of selection of virulent isolates and breakdown of currently deployed resistance.
  • Känkänen, Hannu (MTT Agrifood Research Finland, 2010)
    Disadvantages of invariable cereal cropping, concern of nutrient leaching and prices of nitrogen (N) fertilizer have all increased during last decades. An undersown crop, which grows together with a main crop and after harvest, could mitigate all those questions. The aim of this study was to develop undersowing in Finnish conditions, so that it suits for spring cereal farming as well as possible and enhances taking care of soil and environment, especially when control of N is concerned. In total, 17 plant species were undersown in spring cereals during the field experiments between 1991-1999 at four sites in South and Central Finland, but after selection, eight of them were studied more thoroughly. Two legumes, one grass species and one mixture of them were included in long-term trials in order to study annually repeated undersowing. Further, simultaneous broadcasting of seeds instead of separate undersowing was studied. Grain yield response and the capacity of the undersown crop to absorb soil N or fix N from atmosphere, and the release of N were of greatest interest. Seeding rates of undersown crops and N fertilization rates during annually repeated undersowing were also studied. Italian ryegrass (Lolium multiflorum Lam., IR) absorbed soil nitrate N (NO3-N) most efficiently in autumn and timothy (Phleum pratense L.) in spring. The capacity of other grass species to absorb N was low, or it was insufficient considering the negative effect on grain yield. Red clover (Trifolium pratense L.) and white clover (Trifolium repens L.) suited well in annually repeated undersowing, supplying fixed N for cereals without markedly increased risk of N leaching. Autumn oriented growth rhythm of the studied legumes was optimal for undersowing, whereas the growth rhythm of grasses was less suited but varied between species. A model of adaptive undersowing system was outlined in order to emphasize allocation of measures according needs. After defining the goal of undersowing, many decisions are to be done. When diminishing N leaching is primarily sought, a mixture of IR and timothy is advantageous. Clovers suit for replacing N fertilization, as the positive residual effect is greater than the negative effect caused by competition. A mixture of legume and non legume is a good choice when increased diversity is the main target. Seeding rate is an efficient means for adjusting competition and N effects. Broadcasting with soil covering equipment can be used to establish an undersown crop. In addition, timing and method of cover crop termination have an important role in the outcome. Continuous observing of the system is needed as for instance conditions significantly affect growth of undersown crop and on the other hand N release from crop residues may increase in long run.
  • Aakala, Tuomas (2010)
    Here I aimed at quantifying the main components of deadwood dynamics, i.e. tree mortality, deadwood pools, and their decomposition, in late-successional boreal forests. I focused on standing dead trees in three stand types dominated by Picea mariana and Abies balsamea in eastern Canada, and on standing and down dead trees in Picea abies-dominated stands in three areas in Northern Europe. Dead and living trees were measured on five sample plots of 1.6-ha size in each study area and stand type. Stem disks from dead trees were sampled to determine wood density and year of death, using dendrochronological methods. The results were applied to reconstruct past tree mortality and to model deadwood decay class dynamics. Site productivity, stand developmental stage, and the occurrence of episodic tree mortality influenced deadwood volume and quality. In all study areas tree mortality was continuous, leading to continuity in deadwood decay stage distribution. Episodic tree mortality due to either autogenic or allogenic causes influenced deadwood volume and quality in all but one study area. However, regardless of productivity and disturbance history deadwood was abundant, accounting for 20 53% of total wood volume in European study areas, and 15 27% of total standing volume in eastern Canada. Deadwood was a persistent structural component, since its expected residence time in early- and midstages of decay was 18 yr even in the area with the most rapid decomposition. The results indicated that in the absence of episodic tree mortality, stands may eventually develop to a steady state, in which deadwood volume fluctuates around an equilibrium state. However, in many forests deadwood is naturally variable, due to recurrent moderate-severity disturbances. This variability, the continuous tree mortality, and variation in rates of wood decomposition determine the dynamics and availability of deadwood as a habitat and carbon storage medium in boreal coniferous forest ecosystems.
  • Mäkinen, Antti (Metla, 2010)
    The forest simulator is a computerized model for predicting forest growth and future development as well as effects of forest harvests and treatments. The forest planning system is a decision support tool, usually including a forest simulator and an optimisation model, for finding the optimal forest management actions. The information produced by forest simulators and forest planning systems is used for various analytical purposes and in support of decision making. However, the quality and reliability of this information can often be questioned. Natural variation in forest growth and estimation errors in forest inventory, among other things, cause uncertainty in predictions of forest growth and development. This uncertainty stemming from different sources has various undesirable effects. In many cases outcomes of decisions based on uncertain information are something else than desired. The objective of this thesis was to study various sources of uncertainty and their effects in forest simulators and forest planning systems. The study focused on three notable sources of uncertainty: errors in forest growth predictions, errors in forest inventory data, and stochastic fluctuation of timber assortment prices. Effects of uncertainty were studied using two types of forest growth models, individual tree-level models and stand-level models, and with various error simulation methods. New method for simulating more realistic forest inventory errors was introduced and tested. Also, three notable sources of uncertainty were combined and their joint effects on stand-level net present value estimates were simulated. According to the results, the various sources of uncertainty can have distinct effects in different forest growth simulators. The new forest inventory error simulation method proved to produce more realistic errors. The analysis on the joint effects of various sources of uncertainty provided interesting knowledge about uncertainty in forest simulators.