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Faculty of Agriculture and Forestry

 

Recent Submissions

  • Yassami, Shiva (2022)
    Saccharomyces boulardii is a probiotic yeast related to Saccharomyces cerevisiae but with distinct genetic, taxonomic, and metabolic properties. S. cerevisiae has been used extensively in biotechnological applications. Currently, many strains are available, and multiple genetic tools have been developed, which allow the expression of several exogenous proteins of interest with applications in the fields of medicine, biofuels, the food industry, and scientific research, among others. Although S. boulardii has been widely studied due to its probiotic properties against several gastrointestinal tract disorders, very few studies addressed the use of this yeast as a vector for expression of foreign genes of interest with biotechnological applications. I studied the previously constructed S. boulardii SAC12, which secretes the anti-listerial bacteriocin leucocin C originating from Leuconostoc carnosum 4010. The objective was to study if the bacteriocin leucocin C producing S. boulardii could produce leucocin C in beer fermentation and if leucocin C containing beer can be used as marinade to control Listeria monocytogenes in raw chicken breast strips. The results showed that SAC12 has good ability to secrete LecC, and thus it was used to brew anti-listerial beer. According to results, beer could maintain its anti-listerial activity for 38 days. The anti-listerial effect of the beer stored for different times was analyzed through marinating chicken breast strips (spiked with L. monocytogenes) with the beer for overnight. Results indicated a positive impact of anti-listerial beer in reduction of the viable cells of L. monocytogenes by about 1.6 log from (2.2 ± 0.6) × 10⁷ CFU/g (beer from day 24), and 2.2 log from (1.8 ± 0.3) × 10⁵ CFU/g (beer from day 38). To sum up, the S. boulardii SAC12 efficiently secreted the bacteriocin leucocin C. Brewing beer with S. boulardii SAC12 resulted in beer containing leucocin C. Such beer showed anti-listerial effect when used as marinade for chicken breast strips.
  • Polvivaara, Antti (2022)
    Airborne LiDAR (Light Detection And Ranging) produces high-resolution and cost-efficient 3D data. Currently, forest inventories combine the use of both LiDAR and passive imaging by cameras, and the possibility of using LiDAR only is very tempting as it would lead to cost reduction. Focus of this study is on the full-waveform observations that extent the information content compared to conventional point clouds and are somewhat rarer to have access to. This study explores basic dependencies between structural canopy features and LiDAR signals over time and aims at augmenting our understanding of LiDAR-vegetation interactions and factors limiting our current ability to use pulsed LiDAR data for species detection, and how possibilities to overcome those limitations. Motivation is to understand how different waveform features can be interpreted and how the features behave over time with changing vegetation phenology. The study material consists of three consecutive LiDAR campaigns and aerial imaging surveys done in the area during a 38-month period and field reference trees that have been measured during this period. I use multi-temporal data that comprise three repeated acquisitions, which all applied same sensor, trajectories, as well as sensor and acquisition settings. As I had repeated LiDAR observations of the same trees where the acquisition settings are comparable, I could study the so-called ‘tree effect’ and overall co-variation between waveform features in the repeated acquisitions. Phenological changes are available as the data comprises winter (leaf-off), early summer (low LAI in conifers) and late summer data (full leaf, high LAI). The influence of scan zenith angle (SZA) on waveform features and attributes is also considered, as the same tree can be seen from multiple strips. The results showed that by using careful experimentation it is possible to detect intra- and interspecies phenological changes from multitemporal full-waveform data, while SZA did not have markable effect on the WF features. I was also able to perform well with the tree species classification task in varying phenological conditions. The phenological changes were very apparent on deciduous trees, but rather small on evergreen conifers. In a 45-year-old stand, the overall accuracies in tree species classification were 92, 87 and 88 % for winter, early summer, and late summer, respectively. These figures were 84, 81, and 83 % for in an old growth forest. The ‘tree effect’ was shown to be significant, i.e., many of the WF features of trees were correlated over time. The intra-species feature variance that is due to the tree effect represents natural variation between trees of the same species.
  • Ahokas, Aarne (2022)
    The root rot fungus Heterobasidion annosum is one of the worst conifer pathogens in the boreal forests. Root diseases decrease forest growth, and their abundance could increase with climate change. Disease can reduce the carbon stored into forests even more than wildfires or pest outbreaks, further impacting the climate. Widespread Heterobasidion root rot can develop within the stem of susceptible trees without external symptoms. Therefore, research on the pathogen is difficult on a large extent and its dynamics at the landscape level could be researched with models. A model may be used to understand a system better or to predict its behaviour. Random maps are neutral landscape models, and they are not always significantly different from real random landscapes, except that things shaping real landscapes, such as waterways, human activities, or topography, are missing and the focus is on map cells representing habitats, their occupancy and connectivity across the landscape. Neutral landscape models are an application of percolation theory within landscape ecology; therefore, the connectivity and randomness are important. Heterobasidion spread by sporulation at the landscape level is of interest, as the focus of research has been on the spread by root contacts. In this study, simulations made with Motti and iLand software are compared, the effects of Heterobasidion spread on the dimensional variables of trees at the landscape level are evaluated, and the effects of various maximum dispersal distances on the number of new Heterobasidion colonies and the tree volume per hectare are studied. Forest growth and management practices were simulated with the Motti software, forest dynamics were simulated with the iLand software that uses a neutral landscape model, and Heterobasidion dynamics were simulated with the BITE modelling framework that was connected to iLand for the vegetation and environmental data. Betula pendula had a trend of underestimated values of the dimensional variables except for the basal area in iLand when compared to Motti. There was no clear trend for Picea abies or Pinus sylvestris. Overall, the change in basal area was overestimated the most and height was the most underestimated variable by iLand. A single dimensional variable could have different trends during a forest growth cycle in Motti and iLand. The effect of Heterobasidion on the dimensions of trees at the landscape level was minimal. Larger maximum dispersal distances resulted in more Heterobasidion colonies than shorter distances.
  • Ketonen, Minna-Maria (2022)
    There are many potential ways to reduce CO2 emissions in road freight transportation, of which the utilisation of electrification offers several interesting opportunities. The study analyses the relative cost-competitiveness of battery-electric heavy-duty vehicles and vehicles utilizing electric road system (ERS) to the traditional diesel-powered fleet through the TCO framework. The framework is extended to the cost-effectiveness analysis to consider the external effects regarding vehicle´s life-cycle emissions, and thus the unit cost of the emission reduction achieved through the electrification can be determined. The concrete effects of the electrification of Finnish domestic heavy-duty freight are roughly studied through three arterial roads located in Southern Finland: Helsinki–Turku, Helsinki–Lahti and Helsinki–Tampere. The study utilises existing public research and statistical data on the subject areas. Although the operating costs of the electric trucks are lower than the diesel trucks, only the overhead catenary ERS vehicle in the heaviest 60-ton weight class is less expensive than the equivalent diesel-powered truck in terms of the total cost of ownership. The costs of the battery packs and the catenary line connection in ERS vehicles significantly increases the purchase cost of the electric trucks. Based on the analysis, the emission reduction of 66–79 percent can be achieved with battery-electric trucks and 81–89 percent reduction with ERS-powered vehicles compared to the corresponding diesel-powered vehicles. Although the TCO of ERS vehicles is lower and the achievable emission reduction potential is higher than in the battery-electric vehicles studied, the investment cost of the ERS infrastructure increases the total costs so substantially that the utilisation of battery-electric technology is less expensive option from the society´s point of view. The less expensive life-cycle emission reductions are achieved with the heaviest battery-electric vehicles studied, which according to the analysis, could be achieved with a cost of 139–150 EUR/tCO2. The emission reduction cost of a battery-electric truck without a trailer would be 650 EUR/tCO2. Assuming that it is possible to fully electrify the heavy-duty freight which utilises the studied arterial roads, the total increase in life-cycle costs is approximately EUR 0.7–2.1 billion for battery-electric trucks and EUR 1.5–2.3 billion for ERS trucks. The annual emission reduction potential by replacing fossil fuels with electric vehicles is approximately 0.3–0.5 Mt CO2-eq., which is circa 9–15 percent of the annual emissions of all heavy road freight in Finland. Although the analysis is carefully conducted, it would be fair to say, that significant uncertainties are associated with the background assumptions and data. Already the wide spectrum of the vehicle usage and operating environment can have a major impact to the vehicle characteristics, and thus the results. Further research would also be needed to investigate the effects of the COVID-19 pandemic and the war in Ukraine to the component availability, purchase prices, and changes in fuel and electricity costs. Also, the applicability of electric technology in commercial heavy-duty transportation requires further research.
  • Pellinen, Paula (2022)
    Harvesting pure red clover as silage gives new possibilities to optimize forage feeding of cattle for different animal groups and compromises between plants during cultivating, harvesting, wilting or ensiling are not needed as with mixed swards. This pilot scale preservation study was made as part of Opti-Palko project and the aim was to resolve best practices to ensile pure red clover. Si-lages was made from second harvest pure stands of Selma red-clover and Nuutti timothy and 50% / 50% mixture of those. The crops were ensiled immediately after harvesting and after wilting in dryer. There were five additive treatments comprising of three different acid-based products (formic acid based AIV 2 Plus Na (AIV2), AIV Via (VIA) which includes high proportion of propionic acid, un-corrosive acid mixture buffered with sodium formate (AIVB)) and heterofermentative lactic acid bacteria inoculant Josilac Combi (LAB) and control (KON). Control silages were untreated. Silages were ensilaged in vacuum bags which were opened after a storage period of 12 weeks. After opening chemical composition, microbial quality and aerobic stability were analyzed. The effect of preservatives, dry matter content (DM) (low DM: 114-135 g / kg, high DM ka: 252-305 g / kg) and the proportion of red clover (100-50-0 %) on silage quality and aerobic stability was studied. Sta-tistically significant results between treatments were observed. Wilting increased the quality of silages and well-fermented pure red clover silages were achieved when acid-based additives were used. For example, the concentration of volatile fatty acids was significantly lower than in KON and LAB treatments. In low DM KON and LAB silages very high in acetic acid which didn’t improve aerobic stability in this study but resulted in aerobic unstable silages after around 60 hours. With acid-based additive treated red clover silages, the ratio of ammonia N to total N increased with increasing DM content, which was opposite when compared to other plant materials. This might be due to polyphenoloxidase enzyme (PPO) in red clover, which inhibits the degradation of pro-tein. This study resulted that using silage preservatives is necessary in low DM silages. pH and the content of acetic acid increased with portion of red clover, but lactic acid, propionic acid and etha-nol decreased statistically significantly. AIVB treated silages resulted with same level of quality than other acid-based additive treaded red clover silages, even it was highly buffered to be non-corrosive. The results of this study are useful when choosing preservatives for red clover and gives a new perspective for harvesting silage from pure stands.