Faculty of Agriculture and Forestry


Recent Submissions

  • Pasanen, Miia (Helsingin yliopisto, 2020)
    The aim of this dissertation was to characterize Pectobacterium strains isolated in Finland. Pectobacterium species cause soft rot and blackleg on wide range of plants in cultivated areas worldwide. Potato is an important food crop and source of food cultivated all over the world. Pectobacterium species interfere with potato production at all stages of cultivation. Pectobacterium species belong to the Pectobacteriaceae family with the soft rot bacteria Dickeya genus. In this study, two Pectobacterium model strains, SCC3193 and SCC1, isolated in Finland during 80s and initially defined as belonging to P. carotovorum species were further examined. Biochemical tests of the strains were conducted to understand their characteristics of the bacterial strains and their differences to closely related bacterial strains. The strain SCC3193, originally determined as belonging to P. carotovorum, was redefined as P. wasabiae in the present study. However, it did not fully share the same biochemical profile with the P. wasabiae type strain and based on genome comparisons it was later placed into a novel species P. parmentieri. Furthermore, phylogenetic position of the Pectobacterium strain SCC1 was determined. Also, the strain SCC1 was originally defined as P. carotovorum, but it was observed in the phylogenetic analysis that it clustered apart from P. carotovorum type strain, and thus its taxonomical status could not be confirmed at the time of the analysis. It was later included into a novel species called Pectobacterium versatile. In addition, Pectobacterium strains isolated from diseased potato tubers in 2004, and initially classified as P. carotovorum, were characterized in this study. According to biochemical analyzes, these bacteria isolated from potato stems resembled P. carotovorum but had a low virulence on potato tuber and citrate-negative phenotype. Two genomes of these atypical Finnish stem isolates were produced to study their genome content and phylogenetic position in Pectobacterium genus. Average nucleotide identity (ANI) analysis showed that these isolates were similar to Pectobacterium polaris, a highly virulent new species recently identified in Norway. However, the Finnish isolates were most similar to atypical P. polaris isolates in ANI analysis and biochemical tests. Genome comparisons showed that the all the atypical isolates harbored similar genomic islands not present in P. polaris type strain. Alltogether, taxonomic and genomic studies placed the atypical P. polaris strains into a new subspecies, here called P. polaris subsp. parvum. One of the P. polaris subsp. parvum strains had been isolated in the Netherlands already in 1970s, but originally misidentified as P. carotovotum, which suggests that similar isolates were present in Europe also before. This study provides novel information about the taxonomy and ecology of Pectobacterium species existing in Finland. Taxonomic status of P. carotovorum isolates redefined in this and other studies show that Pectobacterium strains previously included into P. carotovorum species could be divided into several novel species with genome-based methods. The precise identification of bacterial species poses challenges for plant protection. The information from the study can be used for potato production and plant protection in the future.
  • Mattila, Hans (Helsingin yliopisto, 2020)
    White rot Basidiomycota can decompose all wood components in nature and are therefore essential in recycling carbon in our forests and ecosystems. These fungi are filamentous organisms that reside on top of trunks and elongate their hyphae inside wood particles which may be waterlogged or submerged by vegetation and debris. Therefore, it is likely these organisms are occasionally subjected to limited oxygen availability. This doctoral thesis elucidated how this atmospheric shift steers the metabolism of a white rot fungus and how this phenomenon can be used in bioethanol production. This thesis explored a group of white rot fungi for their capability to produce ethanol from wood and lignocellulose containing waste material. One isolate, Phlebia radiata 79 (FBCC0043) turned out to be efficient in producing ethanol from waste substrates in considerable quantities. This isolate was used to develop a single-step single-organism bioethanol production method. A wide range of substrates e.g. saw dust, straw, board and recycled wood waste were used as substrates for ethanol production. Up to 32 g/L of ethanol was obtained from solid-state cultivations with core board. Fungal wood decomposition is considered strictly aerobic; however, Phlebia radiata could convert lignocellulose into ethanol under fermentative and oxygen depleted conditions. Therefore, gene expression of P. radiata was studied after 14 days of cultivation under oxygen depletion or hypoxia. The research concentrated on the expression of both the extracellular carbohydrate active enzymes (CAZy) and the intracellular metabolism. CAZy genes are responsible of encoding enzymes responsible of wood decomposition and the intracellular metabolism is responsible for converting the released sugars into ethanol and other metabolites. Changes in the CAZy gene expression led into changes, for instance, in cellulase activity under hypoxia. In addition, the substantial effect of hypoxia was extended in various intracellular metabolic pathways that were manifested as extracellular accumulation of ethanol and acetate. To conclude, the white-rot fungus P. radiata can decompose untreated lignocellulose in low-oxygen conditions and turn the released sugars into ethanol. Production of ethanol was also achievable on a larger than laboratory scale indicating that a “single-step, single-organism consolidated bioprocess” could be used as a novel method for bioethanol production.
  • Sihvonen, Matti (Helsingin yliopisto, 2020)
    Feeding the growing global population without compromising the long-term productivity and resilience of agroecosystems is a great challenge for global food production. A common view is that optimized nutrient management is central for achieving this goal. This thesis studies the problem of how to manage the long-term nutrition of crop production in a socially optimal way. All the essays in this dissertation rely on mathematical/statistical modeling and dynamic economic optimization. The thesis provides a theoretical and empirical framework for analyzing the influence of soil nutrient dynamics and the externalities on the socially optimal long-term nutrient management in crop production. All numerical applications are based on data and the models describing barley production on clay and coarse-textured soils in a boreal climate. In general, the thesis shows that soil nutrient and carbon dynamics significantly affect privately and socially optimal fertilization management and the optimal agri-environmental policy. The influence of soil texture on optimal nutrient management is highlighted by empirical findings. In particular, the soil’s ability to hold nutrients is an essential factor to be considered. Moreover, the simultaneous optimization of nitrogen and phosphorus nutrients, and organic and inorganic nitrogen fertilizers appears to be beneficial in many ways. Study I makes use of the extensive data sets describing long-term fertilizer field experiments and nonlinear estimation techniques to develop yield response models to nitrogen and phosphorus fertilization. The most crucial relationships determining the crop responses were captured by the developed Cobb-Douglas -type models, as those performed successfully against the independent validation data sets. Study II shows that excessively high legacy nutrient stores, causing environmental damage to waterbodies, are eventually brought down in both private and social optimums by simultaneously optimizing the use of nitrogen and phosphorus fertilizers. Also, catch crops were used as a long-term nitrogen loss abatement measure, whereas gypsum was used only temporally to cut down phosphorus loss on soils with high phosphorus levels. Our results also suggest that a dynamic tax-subsidy scheme can achieve a socially optimal outcome, but in certain specific cases, a simpler static policy instrument may well be cost-effective. Study III focuses on the socially optimal long-term management of nitrogen fertilizer and manure in a situation where water and atmospheric externalities, along with soil nitrogen and carbon dynamics are considered. Our results showed that synergy exists between climate change mitigation and water protection goals and a trade-off exists between pollution mitigation and crop production goals. Synergy was also recorded in certain cases between climate change mitigation and food production goals on clay soils. According to our results, greenhouse gas emission, and nitrogen and carbon leaching mitigation efforts should first be targeted on coarse soils, rather than on clay soils, because the marginal abatement costs are considerably lower on coarse soils.
  • Tupek, Boris (Helsingin yliopisto, 2020)
    Process-based soil carbon models can simulate small short-term changes in soil organic carbon (SOC) by reconstructing the response of soil CO2 and CH4 emissions to simultaneously changing environmental factors. However, the models still lack a unifying theory on the effects of soil temperature, moisture, and nutrient status on the boreal landscape. Thus, even a small systematic error in modelled instantaneous soil CO2 emissions and CH4 emissions may increase bias in the predicted long-term SOC stock. We studied the environmental factors that control CO2 and CH4 emissions in Finland in sites along a continuum of ecosystems (forest-mire ecotone) with increasing moisture and SOC (I and II); soil CO2 emissions and SOC in four forest sites in Finland (III); and SOC sequestration at the national scale using 2020 forest sites from the Swedish national forest soil inventory (IV). The environmental controls of CO2 and CH4 emissions, and SOC were evaluated using non-linear regression and correlation analysis with empirical data and by soil C models (Yasso07, Q and CENTURY). In the upland forest-mire ecotone, the instantaneous variation in soil CO2 emissions was mainly explained by soil temperature (rather than soil moisture), but the SOC stocks were correlated with long-term moisture. During extreme weather events, such as prolonged summer drought, soil CO2 emissions from the upland mineral soil sites and CH4 emissions from the mire sites were significantly reduced. The transition from upland forest to mire did not act as a hot spot for CO2 and CH4 emissions. The CO2 emissions were comparable between forest/mire types but the CH4 emissions changed from small sinks in forests to relatively large emissions in mires. However, the CH4 emissions in mires did not offset their CO2 sinks. In the Swedish data, upland forest SOC stocks clearly increased with higher moisture and nutrient status. The soil carbon models reconstructed SOC stocks well for mesotrophic soils but failed for soils of higher fertility and wetter soils with a peaty humus type. A comparison of measured and modelled SOC stocks and the seasonal CO2 emissions from the soil showed that the accuracy of the estimates varied greatly depending on the mathematical design of the model’s environmental modifiers of decomposition, and their calibration. Inaccuracies in the modelling results indicated that soil moisture and nutrients are mathematically underrepresented (as drivers of long-term boreal forest soil C sequestration) in process-based models, resulting in a mismatch for both SOC stocks and seasonal CO2 emissions. Redesigning these controls in the models to more explicitly account for microbial and enzyme dynamics as catalysts of decomposition would improve the reliability of soil carbon models to predict the effects of climate change on soil C.
  • Laturi, Jani (Finnish Society of Forest Science, 2020)
    Climate change mitigation aims to reduce greenhouse gases in the atmosphere. Forest mitigates climate change by accumulating atmospheric carbon to biomass. This biomass can be used to various products which also act as a carbon sink. Carbon sequestration is the opposite of carbon emission, but not fully. Forest carbon storages are uncertain and temporal but the role of forests as temporary carbon storages still has value. However, climate policy must take this into account both in the implementation of policies and in the valuation of carbon sinks. The thesis consists of four articles and a summary chapter. Articles represent different perspectives of the forest sector and the use of forests and wood products to mitigate climate change. They cover the use of forests from the growth of trees to the use of wood products. In the first article we analyze with an age-class model how forest owners will change their forest management if there is a subsidy based on the forest carbon storage. The results show that enhancing investments for forest growth increases and that forest rotation will be longer. We also investigate how subsidies for silvicultural investment will affect carbon sequestration of the forest. The second article analyses wood consumption and HWP carbon stock in Finland until 2050. The main HWP carbon pool consists of products made of sawn wood. The HWP carbon pool in Finland seems to increase until 2050 even in the case of decreasing consumption of sawn wood. The third article deals with optimal forest management where the growth of the forest is described by a size-class model. The results show a feature on size-classified matrix models that significantly reduces the comparability of forest management results of these models. The optimal thinning intensity and rotation length of forest are highly dependent of the specification of the model. The fourth article analyzes the existing climate policy for forestry in the EU. Because the policy only applies to one period, we can use a simple two-period model to describe the impact of the policy. The results show that constraints on current climate policy design reduce the potential of using forests to mitigate climate change. The framework in the summary of the articles complements the conclusions in the articles and builds a view towards a more comprehensive conclusion for governance of forest sector to mitigate climate change.
  • Hyder, A. B. M. Rafiqul (2020)
    Species of the Heterobasidion annosum sensu lato (s. l.) complex are causing root and butt rot of conifers. Mycoviruses are usually cryptic, but some of them may cause hypovirulence (reduced virulence) or mutualistic effects on their fungal hosts. We explored new Heterobasidion viruses, and analyzed their taxonomy and effects on their hosts. The viruses were obtained from fungal culture collection of the Natural Resources Institute Finland (Luke) or from newly collected isolates.This thesis addressed the taxonomy of Heterobasidion viruses as well as their transmission, effects on hosts’ phenotypes, and distribution. A new dsRNA virus from H. annosum s.s., Heterobasidion RNA virus 6 (HetRV6), was taxonomically distant from all previously known viruses of Heterobasidion spp., but related to the mutualistic Curvularia thermal tolerance virus. Populations of this species exhibited a considerable degree of geographical and host-related differentiation. Virus isolates HetRV6-ab6 and Heterobasidion partitivirus 3 (strain HetPV3-ec1) conferred different and condition-dependent effects on different host strains. Four new partitivirus species, HetPV12, HetPV13, HetPV14 and HetPV15, clustered in a clade within the genus Alphapartitivirus, that includes also HetPV3 and Helicobasidium mompa partitivirus V70. HetPV13 strains were found to have a high dispersal capacity. A high infection rate by four species of partitiviruses was observed in H. annosum in a heavily infected forest. Two of these species were previously unknown (HetPV16 and HetPV20). Three fungal isolates were co-infected by two different partitiviruses (HetPV13-an2 and HetPV7-an1 or HetPV16-an1 and HetPV20-an1), supporting the view that multiple infections are common.Taken together, the global diversity and prevalence of Heterobasidion viruses is considerable, and their transmission may occur between somatically incompatible strains. They may co-infect single host strains, transmit over species borders and confer variable phenotypic effects on their hosts. Further studies are necessary to determine the biocontrol potential of these viruses.
  • Seppälä, Arja Tuulikki (Helsingin yliopisto, 2020)
    Total mixed ration (TMR) is a feeding method for ruminants. Prior to feeding different types of feed ingredients are mixed together to create a uniform moist mass. TMR provides favourable conditions for microbial growth, which can cause rapid spoilage and spontaneous heating of the feed especially during the warm season. Potential negative consequences of the TMR heating are dry matter (DM) losses, reduced feed intake and subsequent reduction in animal production. The objective of this thesis was to explore the factors affecting TMR stability. Silage is normally the most important component of a TMR. The effect of silage stability on TMR stability was evaluated by varying both silage additive and silage DM concentration. The ensiled crops were grass (a mixture of timothy and meadow fescue) and faba bean-wheat and field pea-wheat whole crops. The grass was ensiled at two dry matter levels: 218 (LDM) or 539 (HDM) g kg-1. The whole crops were dominated by legumes as their proportions were 0.84 (faba bean) and 0.89 (pea) and DM was low (173 and 181 g DM kg-1, respectively). Ensiling trials were conducted in 12 L silos. Each silage from the ensiling trials was used to prepare a TMR by adding various concentrate components. Aerobic stability of both the silage and the TMR was measured by following the temperature rise in the feed materials during aerobic exposure. Silage stability was directly linked to TMR stability of the additive treated silages within crop. On the contrary, non-additive treated LDM silage had stability of 13.8 days while the TMR prepared from that silage had a stability of only 10 hours. TMR DM was 590 g kg-1 and 330 g kg-1 for HDM and LDM, respectively. Numerically TMR prepared from HDM silages had 69 hours longer stability than TMR prepared from LDM silages. Conversely, TMR prepared from whole crop legume silages had only 280 g DM kg-1, and yet their stability was relatively good (> 45 hours). It is notable, that silages were introduced into TMR immediately after silo opening without any semi-aerobic feedout phase. The stability of the LDM silages was on average 12 times longer than the stability of the respective TMR. Legume whole crop silages had a stability 1.4 times higher than the respective TMR. The range of the silage additive effect on the TMR stability was 13 hours for faba bean-wheat silages, 30 hours for LDM silages, 57 hours for pea-wheat silages and 82 hours for HDM silages. Preservatives can be added into TMR at the time of mixing to delay the spoilage. Two trials were conducted to explore the effects TMR hygieny and preservative additions. Effects of both liquid and solid preservatives were investigated as a method to delay TMR heating. The hygiene level of TMR was varied by an inclusion (10 % on DM basis) of one-week-old TMR into the mixture, by inclusion of brewers grains (13 % on DM basis) or by the quality of the grass silage (fresh or after aerobic exposure). The preservative added into TMR at the time of mixing improved TMR stability on average by 1.5 to 41 hours depending on the microbial status of the TMR and the application level of the preservative. The effects of chemical stabilizers were larger, when the Control TMR had good stability. Low yeast count (< 3 log10 cfu g-1) of the TMR was related to good stability. A high yeast count (> 5 log10 cfu g-1) and consequent rapid TMR heating may be caused by inoculation in the form of high yeast containing components such as by brewers grains or sometimes by silages. Together with yeasts, also aerobic bacteria may play a role in TMR spoilage, as suggested by the high count of aerobic bacteria (9.8 log10 cfu g-1) in aerobically spoiled silage. Poor hygiene reduced TMR stability by 50 hours. The amount of yeasts, moulds and aerobic bacteria, respectively, were 55, 257 and 126 times higher in TMR containing 26 % spoiled silage (on DM-basis) compared to the TMR prepared from high hygienic quality ingredients. It was concluded that silage additives can manipulate silage and respective TMR aerobic stability. Within additive treated silages there was a strong correlation between silage stability and TMR stability. High dry matter grass silages and TMR prepared from them had good stability in the trial conditions, which may not reflect practical situation on farms where presense of oxygen is more variable during silo filling, during ensiling as well as during feed out potentially causing substantially higher count of aerobic spoiling microbes than in trial silos. Chemical TMR preservatives can improve TMR stability especially effective when the initial number of spoiling organisms is low. Keywords: aerobic stability, hygiene, preservative, spoilage, total mixed ration, yeast
  • Honkanen, Anne (Helsingin yliopisto, 2020)
    Lipids in bovine feed consist mainly of unsaturated fatty acids, such as linoleic acid (LeA) and alpha-linolenic acid (LnA). Some bioactive fatty acid isomers, formed as biohydrogenation (BH) intermediate products in rumen, may confer potential benefits to long-term human health. The objective of the research described in this thesis was to characterize the formation of BH intermediates during incubations of LeA and LnA with bovine rumen fluid, with the potential to identify new BH intermediates and mechanisms of the BH pathways. Emphasis was placed on the unknown BH intermediate products. Experiments encompassed in vitro trials with pure fatty acids. The fatty acid composition was determined using a gas chromatography-mass spectrometry and a high-performance liquid chromatography. Incubation of incremental doses of LeA resulted in a dose- and time-dependent accumulation of geometric isomers of Δ9,11 conjugated linoleic acid (CLA) and Δ10,12 CLA, a wide range non-conjugated (NC) 18:2, cis 18:1, and trans 18:1 intermediates. Several novel intermediates, including NC cis-7,cis-12 18:2 and cis-8,cis-12 18:2, were found to accumulate in direct relation to the amount of added LeA, providing the first indications that BH of LeA by ruminal bacteria may also involve mechanisms other isomerization of the cis-12 double bond. Reductions of 18:2 to 18:1 intermediates and 18:1 to 18:0 occurred at lower rates compared with the formation of CLA and NC 18:2 isomers. At the lowest doses, the end-product was 18:0. The highest amount of LeA inhibited the complete reduction of LeA to 18:0. Incubation of incremental doses of LnA resulted in an accumulation of geometric isomers of Δ9,11,15 conjugated linolenic acid (CLnA), Δ9,11,13 CLnA, novel NC 18:3, including cis-7,cis-12,cis-15 18:3 and cis-8,cis-12,cis-15 18:3, NC 18:2, such as cis-12,cis-15 18:2, trans-10,cis-15 18:2, and trans-11,cis-15 18:2, CLA isomers, such as trans-11,trans-13 CLA and trans-12,trans-14 CLA, and 18:1. Amount of 18:0 as an end-product did not increase in response to LnA addition. Reductions of 18:1 and 18:2 intermediates occurred at lower rates than the formation of 18:2 isomers. All transfer rates decreased by increases in LnA addition. The mechanisms of the formation of BH intermediates was studied by incubating LnA with bovine rumen fluid and buffer prepared using D2O. The major LnA BH pathway involves the isomerisation to yield cis-9,trans-11,cis-15 CLnA by a mechanism that resembles the formation of Δ9,11 CLA from LeA indicating 2H labeling at C-13. The novel NC 18:3 intermediates were formed without an apparent exchange of protons from water. Enrichment in n+2 isotopomers of trans-11,cis-15 18:2 was detected due to 2H labelling at C-9 and C-13. The locations of the two 2H labels in the cis-12,cis-15 18:2 and trans-10,cis-15 18:2 could not be detected. The present doctoral thesis work investigated the structure of the major and minor fatty acid isomers formed from LeA and LnA, some of which have not been characterized previously, and possible mechanisms involved in the initial stages of LnA BH by rumen microbiota. The novel isomers identified in this thesis have been used to update the BH pathways of LnA and LeA. These findings explain the appearance of several fatty acids in muscle and milk that influence the nutritional value of ruminant-derived foods.
  • Niskanen, Olli (Helsingin yliopisto, 2020)
    Livestock production has been shifting towards larger production units, with the number of small livestock farms rapidly decreasing as a result. This dissertation examines the impact of this structural change in Finland and Northern Europe as it affects agricultural land use. The work comprises three substudies as well an introductory synopsis. It contributes to the literature through insights into the possible side-effects of the structural development studied, which highlights issues that deserve special attention. In most instances, efforts to achieve economies of size account for past and ongoing growth in farm size: Farms seek possibilities to gain efficiency and productivity in order to keep their viability in the face of growing production costs. In the case of Finnish dairy farms, increased productivity is mostly attributable to advances in technology. Average technical efficiency has increased but only slightly; more importantly, a higher share of the total production volume is produced with higher technical efficiency. One factor affecting the technical efficiency of dairy farms is parcel structure, that is, the size of and distance to field parcels. Improving parcel structure would thus be an ap-propriate measure in the effort to improve technical efficiency. One alternative to high-intensity production that has been put forward is a strategy based on low input use. In the northern European context, clover-grass-based for-ages are suitable for sustainable low-input or organic dairying. They are advantageous in that they require less nitrogen fertilization than pure hay grasses yet provide a higher protein content for livestock. While any incentive to cultivate clover-grass was found to be highly dependent on the price of nitrogen, increasing the yield of clover-grasses (i.e., decreasing the gap in yield vis-à-vis intensive grass production) would also effectively promote clover cultivation. Significantly, this would not entail additional costs for milk producers or society, a finding arguing for encouraging the development of clover varieties and cultivation practices. Yet, the potential for clover-grass was found to be limited due to the excessive quantity of manure nitrogen at average dairy farm stocking rates. As livestock farms that continue to operate are growing larger and housing more animals, effects can be expected where the use of manure is concerned. The crux of the issue is the nutrient composition of manure: By the year 2030, farms housing more than 500 livestock units will likely produce more than two-thirds of all manure phosphorus, whereas the proportion in 2010 was one-third. This development would in-duce a need for growing farms to acquire 4.9 million hectares of land from exiting farms in order to meet the current manure spreading requirements. This shift represents 64% of the total area available for spreading in 2010 and 15% of the total utilized agricultural area of the regions studied. The results suggest that despite it being economically justified to seek economies of size in agriculture, contrasting and/or countervailing tendencies can be identified that are related to land management. These tendencies 1) reduce efficiency, 2) limit cultivation opportunities and 3) lead to the concentration of nutrients on fewer farms. Structural development – livestock farms becoming larger – creates pressure to develop new nutrient solutions. An awareness of these issues is crucial when agri-environmental policies are developed. The present research indicates that it is justified to promote land-use efficiency in livestock farming through farm consolidation pro-grams and by promoting cooperation between farmers. It is also advisable to enact manure nutrient regulation in the supranational context. Keywords: agriculture, structural change, livestock farms, efficiency, intensity, agglomeration
  • Pyörälä, Jiri (Helsingin yliopisto, 2020)
    Managed forests play crucial roles in ongoing climatic and environmental changes. Among other things, wood is capable of sinking and storing carbon in both standing timber and wood products. To promote these positive effects, more precise planning is required that will ensure sustainable forest management and maximal deposition of harvested wood for long-term applications. Information on wood properties plays a key role; i.e. the wood properties can impact the carbon stocks in forests and the suitability of wood for structural timber. With respect to the theoretical background of wood formation, stem, crown, and branching constitute potential inputs (i.e. wood quality indicators) to allometric wood property, tree biomass, and wood quality models. Due to the complex nature of wood formation, measurements of wood quality indicators that could predict wood properties along the relevant directions of variation have previously been elusive in forest inventories. However, developments in laser scanning from aerial and terrestrial platforms support more complex mapping and modeling regimes based on dense three-dimensional point clouds. The aim here was to determine how wood properties could be estimated in remote-sensing-aided forest inventories. For this purpose, methods for characterizing select wood quality indicators in standing timber, using airborne and terrestrial laser scanning (ALS and TLS, respectively) were developed and evaluated in managed boreal Scots pine (Pinus sylvestris L.) forests. Firstly, the accuracies of wood quality indicators resolved from TLS point clouds were assessed. Secondly, the results were compared with x-ray tomographic references from sawmills. Thirdly, the accuracies of tree-specific crown features delineated from the ALS data in predictive modeling of the wood quality indicators were evaluated. The results showed that the quality and density of point clouds significantly impacted the accuracies of the extracted wood quality indicators. In the assessment of wood properties, TLS should be considered as a tool for retrieving as dense stem and branching data as possible from carefully selected sample trees. Accurately retrieved morphological data could be applied to allometric wood property models. The models should use tree traits predictable with aerial remote sensing (e.g. tree height, crown dimensions) to enable extrapolations. As an outlook, terrestrial and aerial remote sensing can play an important role in filling in the knowledge gaps regarding the behavior of wood properties over different spatial and temporal extents. Further interdisciplinary cooperation will be needed to fully facilitate the use of remote sensing and spatially transferable wood property models that could become useful in tackling the challenges associated with changing climate, silviculture, and demand for wood.
  • Stefański, Tomasz (Helsingin yliopisto, 2020)
    This work focuses on studying rapeseed meal (RM) protein degradation and utilization in dairy cows. Rapeseed meal was selected as a source of protein as it is widely used and cultivated in the European Union, and can be used to replace soybean meal in the rations of lactating dairy cows. This thesis comprises three experiments. Two experiments were conducted using in vitro and in vivo techniques. The objectives of the work were to establish an in vitro method to study protein metabolism in the rumen (Publications I and II), to study the metabolism of ammonia N and soluble fractions of RM protein in vivo (III), and to study the efficiency of utilization of different N fractions for milk protein synthesis (IV). The in vitro experiment documented in publication I involved a preliminary study to develop a mixture of carbohydrates to ensure high proteolytic activity and constant microbial N synthesis over the entire in vitro incubation period. In the main trial, the in vitro method was established to study the rate of ruminal degradation of RM protein based on observations of 14N and 15N isotope fluxes between ammonia N and non-ammonia N pools. In this study, feed protein was incubated with rumen fluid, mineral buffer and a carbohydrate mixture. The ammonia N pool was labelled with 15N isotope, and the incubations were carried out for 10 h with 11 sampling times. The rate of RM degradation estimated with a six-pool model was 0.06/h with an effective protein degradation of 0.38. This approach of studying protein degradation in vitro seemed to be appropriate for determination of microbial N synthesis from ammonia N but it did not provide sufficient information on metabolic events involved in ruminal protein degradation and microbial protein synthesis from preformed amino acids. A novel in vitro method developed to study the metabolism of soluble RM protein was presented in Publication II. In this experiment, unlabelled and 15N labelled soluble fractions of RM were incubated for 10 h with 11 sampling times along with buffered rumen fluid and a carbohydrate mixture. A four-pool model involving pools of 14N and 15N isotopes of ammonia N, soluble non-ammonia N, and insoluble-N from unlabelled and 15N labelled soluble RM incubations was used to estimate parameter values. The mean rate of soluble RM protein degradation was 0.126/h. There was no substantial difference in the rate of protein degradation and microbial N synthesis between the unlabelled and 15N labelled soluble RM. In conclusion, combined data from incubations of unlabelled and 15N labelled soluble RM provided sufficient information for estimation of parameter values in a complex dynamic model of soluble protein degradation. The results also indicated ruminal escape of soluble protein. The ruminal in vivo metabolism of 15N labelled ammonia N and a soluble N fraction of 15N labelled RM protein introduced into the rumen were presented in Publication III. Four lactating dairy cows equipped with rumen cannulae were used in this study. The cows consumed a total mixed ration (60% of silage and 40% of concentrates on DM basis) with 15.5% of crude protein on DM basis, with average rumen ammonia N concentration of 5.5 mg/100mL. The metabolism of ammonia N occurred at a very fast rate, with 99.4% of the original dose disappearing from the ammonia N pool in 4 h. The ammonia N was mainly incorporated into microbial N as 69% of the 15N labelled ammonia N dose disappeared from the rumen as microbial N. In the metabolism of soluble RM protein two steps were observed: 1) an almost instant uptake of more than half of the soluble non-ammonia N (SNAN) dose by the rumen bacteria 2) followed by slower degradation rate of the remaining fraction of the soluble RM protein. It was estimated that 8% of the soluble RM protein N escaped the rumen as feed N. SNAN had a higher initial uptake of the dose than ammonia N (AN) (56 vs. 16%). Also, the outflow as non-ammonia N from the rumen was higher for the SNAN than for AN treatment (89 vs. 69%). More N disappeared (outflow and absorption) from the rumen as ammonia N for the AN treatment than for SNAN treatment (31 vs. 11%). These observations suggested that SNAN was better utilized in the rumen than AN. Higher outflow of microbial N for the SNAN than for AN treatment (81 vs. 69%) indicated that preformed AA and small peptides stimulated microbial growth. The efficiency of utilization of AN, soluble and insoluble fractions of RM protein N for milk protein synthesis were described in Publication IV. The average efficiency of N utilization for milk protein synthesis (milk N/N intake) in this study (32%) was in the higher end of the range reported in the literature (typically from 14% to 36% but in some cases up to 45%). The cumulative secretion of isotope 15N in milk at 108 h post dose indicated that the three studied N fractions had different efficiency of N utilization for milk protein synthesis. The lowest efficiency of N utilization was estimated for AN (19%), followed by the soluble RM fraction (20%), and the highest efficiency of N estimated for the insoluble RM fraction (22%). These differences were smaller than could be expected based on the current protein evaluation systems. Keywords: dairy cows, soluble protein metabolism, ammonia, isotope 15N, rapeseed, efficiency of utilization of N for milk protein synthesis
  • Perttilä, Sini (2020)
    The aim of this thesis was to determine the ileal amino acid digestibility values in the most commonly used feed ingredients for poultry in Finland. Four experiments were conducted to determine the apparent amino acid digestibilities of cereals (barley, oats, wheat, triticale and maize) and protein ingredients (rapeseeds, rapeseed cake, rapeseed meal, soybeans, soybean cake, soybean meal and meat and bone meal) for broilers (in publication I, II, III and IV) and adult cockerels (I). The flows of basal endogenous amino acids at the distal ileum of the broilers were determined using a protein-free diet (IV), and standardised ileal amino acid digestibilities were calculated for wheat, soybean meal and rapeseed meal (IV). Further, the effects of β-glucanase supplementation and preservation method of barley on apparent ileal amino acid digestibility (AID) in broilers and cockerels were determined (I). The ileal digestibility values were determined using the slaughter technique and chromium mordanted straw as an indigestible marker. Finally, apparent ileal digestible lysine based feed formulation was compared to total lysine based feed formulation for broilers (IV). Lysine AID was lower in barley than in triticale and wheat, but did not differ from dehulled oats, oats and maize (II). Methionine AID was the lowest in barley, intermediate in oats, wheat and dehulled oats and highest in maize but maize did not differ significantly from triticale and dehulled oats. In addition, methionine AID in wheat did not differ from dehulled oats and triticale. Furthermore, cysteine AID was highest in wheat, triticale, maize and barleys and lowest in oats but oats did not differ from dehulled oats and maize. Threonine AID was similar among all the grains. Among the protein ingredients, lysine AID was highest in soybean cake, soybean meal and full-fat soybeans, intermediate in rapeseed cake, rapeseed meal and meat and bone meal and lowest in rapeseeds but rapeseeds did not differ from meat and bone meal and rapeseed meal (III). Methionine AID was lowest in meat and bone meal and full-fat rapeseeds, intermediate in full-fat soybeans, rapeseed meal and rapeseed cake and highest in soybean meal and cake, but soybean meal and cake did not differ from rapeseed cake. Cysteine AID was lowest in meat and bone meal and rapeseed meal, intermediate in rapeseed cake and rapeseeds and highest in soybean cake, soybean meal and full-fat soybeans. Threonine AID increased from full-fat rapeseeds and meat and bone meal to rapeseed meal, further to rapeseed cake and onwards to full-fat soybeans, soybean meal and cake. Threonine AID in meat and bone meal did not differ from rapeseed meal, and rapeseed cake did not differ from full-fat soybeans. The AID of cysteine and proline in dried barley containing diets were lower than in air-tightly stored and ensiled barley containing diets (I). The AID of alanine, glutamic acid, isoleucine, methionine, phenylalanine, and proline were lower in air-tightly stored barley compared to that in ensiled barley. The enzyme β-glucanase improved the AID of amino acids in the dried barley containing diet for broilers, but had no effect on the air-tightly stored and ensiled barley containing diets for broilers, or on any diets for cockerels. Amino acid AID was lower in broilers than in cockerels. The predominant basal endogenous amino acids were aspartic acid and glutamic acid and the lowest ones present were methionine and histidine (IV). Lysine and threonine standardised ileal digestibility (SID) was lower in rapeseed meal compared to that in soybean meal and wheat. Methionine SID was similar among soybean meal, rapeseed meal and wheat. Cysteine SID was much lower in soybean meal and rapeseed meal (21.8 and 21.4 %-units lower, respectively) than that in wheat. Differences in amino acid digestibility values of tested ingredients could be explained by variation in chemical composition. Structure of protein fractions and fibre, non-starch polysaccharides and anti-nutritional factors affect digestibility of ingredients. Ingredients with higher fibre content such as cereals and rapeseed products had lower amino acid digestibilities than low fibre ingredients such as soybean meal. The difference between amino acid AID and SID values were the highest in wheat and decreased from rapeseed to soybean meal. The results from growing experiment (III) imply that formulating diets based on a lysine AID was better than that based on total lysine when diets contained protein sources of low amino acid digestibility such as meat and bone meal and rapeseed meal. Variation in the difference between amino acid AID and SID values of different ingredients explains the need to standardise and use standardised amino acid SID values in feed formulation. The amino acid digestibility values measured in current experiments could be added to Finnish feed tables. This would allow formulate more accurately the crude protein-feeding of broilers fed diets composed of different feed ingredients. Keywords: broiler, cereal, protein ingredient, apparent, standardised, diet formulation
  • Heim, Anita (Helsingin yliopisto, 2020)
    The diets of former hunter-gatherers, and the diets of many Indigenous Peoples worldwide, are changing at a fast pace, and malnutrition has become a widespread problem. Several reports highlight the severity of food insecurity among the San people - a generic term for several Southern African Indigenous ethnic groups – calling for research to investigate the quality and specificities of their contemporary diet and its influencing factors. This dissertation is the outcome of a four-year multidisciplinary study aiming to understand the underlying causes of food and nutrition insecurity among a Namibian San community, the Khwe San people in Bwabwata National Park (BNP). Experiencing rapid changes in socio-cultural and environmental settings over their recent history, and being the target of many development projects, their traditional food system has undergone substantial changes over the past few decades, and little has to date been done to examine these changes or the implications they may have. The dissertation applies a food systems approach in an attempt to understand the contemporary food environment and food choices of the Khwe San and assesses one particular food strategy, namely crop cultivation in more depth, both from community and stakeholders’ perspectives. The study began with an initial ethnographic phase, followed by qualitative and quantitative data collection throughout three extended periods of fieldwork (five months each) between 2016 and 2018 in the eastern part of BNP. Research methods included participant observation, a socio-economic survey, a dietary intake survey, structured and semi-structured interviews, and village meetings. The findings of this dissertation demonstrate that the dietary diversity of the study population is extremely low (the average dietary diversity score was below 2.5 out of 10). No direct association was found between socio-economic variables and diet quality. Further research of the food environment provided some explanations for the low dietary diversity score, with several nutritional food groups missing from the local food environment. Among the local food sources, bush, governmental food aid and agricultural fields are perceived by the Khwe as being the most important. However, the restricted and recently denied access to bush habitats due to externally imposed conservation regulations had caused severe perturbations in the local food availability. The importance of crop cultivation was ranked highly, although its dietary contribution was found to be minimal. In-depth interviews with Khwe elders reveal how historical and political events and cultural norms have shaped diets over the past five decades. Current preferences for traditional foods was found to be divided, strongly influenced by access, but traditional food preferences have also declined due to erosion of traditional knowledge. This study found the main determinants of current Khwe food choices to be sensory drivers, access, food insecurity, costs, and health concerns. Nevertheless, substantial gaps in nutritional knowledge prevent many of the Khwe from making informed food choices. Assessment of the most advocated food strategy in BNP, namely crop cultivation, reveals that both institutional factors and local practices are influencing the poor production outcome. Despite the centralised governmental support efforts, yields remain low due to the incompetence, conflicts and disharmonised approaches between the various governmental institutions. The study describes the current state of community capitals and the environmental context within which crop cultivation takes place, all of which play a defining role in outcomes, but remain largely disregarded by the highly authoritative governmental agencies. This dissertation contributes to the growing body of knowledge on food environment and food choice studies in rural settings of low- and middle-income countries by introducing new conceptual and methodological nuances. Moreover, the principal findings point to the fact that the Khwe San lack access to adequate food in terms of quantity, nutritional value and cultural meaning. The Khwe are trapped in a vicious cycle of malnutrition due to a dysfunctional local food system in which they have no agency over the food sources, and are deprived of access to their natural food resources on their traditional lands. This violates the United Nations Declaration on the Rights of Indigenous Peoples and contradicts the human right to food. The results of the dissertation anticipate guiding future policy and development interventions to improve dietary adequacy among San people by: ensuring access to nutritious foods in an inclusive, participatory manner; supporting informed dietary behaviour; strengthening community capitals, and; fostering positive change in the food environment. National and regional policy and practice need urgent reform in order to secure user rights over land and resources, and to ensure a just food system for the Indigenous inhabitants of the BNP.
  • Kosunen, Maiju (Finnish Society of Forest Science/ Faculty of Agriculture and Forestry of the University of Helsinki/ School of Forest Sciences of the University of Eastern Finland, 2020)
    The importance of forests and soil in carbon (C) sequestration and storage is continually increasing with climate change. Disturbances, such as storms and insect outbreaks, are the drivers of forest functioning, composition and structure, and many of them are predicted to become more common in the future. However, environmental factors that predispose forests to disturbance as well as the diverse effects of disturbances on forest C cycling are not fully known. In this dissertation, stand, site and soil characteristics predisposing forest stands to outbreaks of two common insect species that can cause tree damage and mortality—the common pine sawfly (Diprion pini L.) and the European spruce bark beetle (Ips typographus L.)—were examined, and the impacts of storm and I. typographus disturbance on soil respiration, tree and soil C stocks, and microbial community composition and associated C contents were investigated in forests located in eastern and southern Finland. The level of tree damage by D. pini and I. typographus in managed Scots pine (Pinus sylvestris L.) and urban Norway spruce (Picea abies (L.) Karst.) forests, respectively, were associated with various site and soil characteristics. Defoliation of P. sylvestris by D. pini was more severe on sites with soil properties indicating greater fertility (e.g. lower soil C/N ratio and finer textured). Highest cumulative probabilities for severe I. typographus infestation of P. abies were associated with trees growing on sites having an east-facing aspect and the most fertile site types combined with either moderately steep slopes, shallow till soil or high soil C/N ratio. The effects of storm and I. typographus (5–7 years and circa 1–4 years after tree mortality, respectively) disturbance on forest C were studied in P. abies dominated forests that had been left unmanaged after disturbance. Soil surface total and heterotrophic CO2 effluxes, and topsoil C stocks of storm and I. typographus disturbed and undisturbed sites differed little, despite the shift in tree C stocks from living to dead after both disturbances and greater litter detritus C stocks on the I. typographus disturbed sites. Soil surface autotrophic CO2 effluxes were mostly lower at the disturbed sites than at undisturbed ones. The most distinct differences in the humus layer microbiology were the lower abundances of tree-symbiotic ectomycorrhizal fungi, and consequently slightly lower microbial and fungal biomasses in the storm and I. typographus disturbed sites in comparison to the undisturbed sites. The remaining living trees on or in close proximity to the disturbed sites probably mitigated the belowground response to disturbance to some extent. This dissertation shows that certain site and soil characteristics predispose trees and forest stands to D. pini and I. typographus infestations, which could help in identifying sites that are susceptible to insect disturbance. Furthermore, it provides new information about the short-term effects of natural disturbance on boreal forest C cycling and soil microbiology, which is important for improving understanding of the complexity of the possible impacts of climate change on forest C sequestration.
  • Paljakka, Teemu (Helsingin yliopisto / Suomen Metsätieteellinen Seura, 2020)
    Tree vascular tissues connect resource availability to tree physiological processes and growth. The xylem transports water from the soil up to the canopy of even 100-metre tall trees, whereas phloem transport connects the photosynthesis in leaves and the tree metabolic processes, including growth and tree defences against insect and pathogen attacks. Water deficit results in the closing of leaf stomata and decreasing photosynthetic production, as water and carbon dioxide are exchanged through the stomata between the leaf and ambient air. Phloem transport is driven by turgor pressure gradients generated by the interplay of phloem osmotic concentration and xylem water potential. Trees have adapted to local environmental conditions and they adjust to fast environmental changes with physiological responses. This thesis investigates tree physiological responses in vascular tissues, such as osmolality, water potential and stomatal conductance, to environmental conditions in two conifers: Scots pine and Norway spruce. Seasonality in soil temperature and soil water content affect soil-to-leaf hydraulic conductance, and stomatal conductance is connected to these seasonal patterns in water transport. Soil environment is thus mediated to tree functionality through tree water transport. This thesis also supports Münch’s theory that it is plausible to explain phloem transport in conifers in field conditions with osmotic gradients and gravity. Xylem water potential reflects to osmotic potential and turgor pressure of the inner bark by modifying tissue solute and water content. The turgor gradients hence seem to determine daily and seasonal carbon allocation patterns according to water availability. Pathogenic infections may introduce more rapid changes in tree hydraulic conductance through a decrease in xylem sap surface tension and xylem conductivity during massive invasions of bark beetles that vector blue-stain fungi such as Endoconidiophora polonica. These pest attacks weaken tree vitality and may also increase tree vulnerability to hydraulic failure in the xylem.
  • Marttinen, Eeva (Helsingin yliopisto, 2020)
    Knowledge of the defense responses of mosses against pathogens has gained less attention than has our knowledge of the pathogens of vascular plants. Recently, the use of mosses has gained attention because mosses are used for greenhouse production as well as landscaping. In particular, the landscaping and greening of buildings have become popular because these initiatives offer one solution for mitigating urban problems such as heat islands and flooding. Mosses are an easy and lightweight solution for greening purposes as they can survive the harsh rooftop environment and have great stormwater retention. However, the health of plants is fundamental to achieving the benefits of greening. Like vascular plants, mosses also are susceptible to plant diseases. Many fungi damage mosses by causing brown patches of greenish moss. Brown patches on mosses are a characteristic sign of fungal infection. However, plants have various defense mechanisms, the first of which consists of preexisting structural and chemical defenses. Second, the plant immune system uses specific receptors with which to recognize the molecular structures of microbes that are not present on the surface of the plant's own cells. Receptor-mediated sensing of these structures can trigger early defense responses of plant, which can make the plant resistant to the attacking microbe. The model moss Physcomitrella patens, like the vascular plants, senses the molecular structures of microbes. For example, exposure of P. patens to chitosan—a component of the fungal cell wall—significantly increases peroxidase activity and oxygen radical formation. Oxygen radicals in turn affect many biological events; they can directly damage the pathogen or stimulate the plant's defenses. Currently, little is known about the peroxidase-based defense as well as chitosan-induced signaling pathways of P. patens. The aim of the research presented in this thesis was to study the pathogens of green roof mosses and establishes the host range of the isolated pathogens; the study also utilized a Physcomitrella mutant collection to identify genes involved in chitosan-induced signaling pathway. Fungal species that naturally inhabit mosses at a moss farm in Japan and on green roof environments in southern Finland were isolated and the ability of these fungi to infect and cause disease symptoms on the model moss P. patens was tested. In addition, the pathogenicity of fungus species towards vascular plants was also assessed. To elucidate the genes involved in chitosan-induced peroxidase activity, part of the Physcomitrella mutant collection was screened using the oxidation of 2,2´-azino-bis(3-ethylbenzothiazoine-6-sulfonic acid) as an indicator of peroxidase activity. Genome walking analyses were used to identify which genes were mutated within each moss line of interest. The work described in this thesis demonstrates that mosses used for greening are colonized by many different fungal isolates. These studies reveal that several fungal genera such as Fusarium, Trichoderma, Phoma and Alternaria cause severe symptoms in P. patens. Moreover, our results demonstrate that mosses and vascular plants have common pathogens. The fungal isolates Fusarium avenaceum and Cladosporium oxysporum obtained from moss panels caused disease symptoms on barley and carrots, respectively, and also on two different moss species. The results also demonstrate that the Physcomitrella mutant collection is a valuable source for identifying genes involved in the chitosan-induced signaling pathway. Screening of part of the mutant collection and further analyses revealed that Rossmann fold protein is a significant part of the signaling chain leading to upregulated peroxidase activity induced by chitosan. In addition, this Rossmann fold protein is an important factor for normal lipoxygenase (LOX) expression and might contribute to defense against fungal pathogens. The results from this doctoral thesis provide new insights into the pathogens of green roofs, the host range of the pathogens and the molecular mechanisms involved in disease control and defense responses in moss. The knowledge gained concerning the pathogenicity of Trichoderma isolates and the host range of pathogenic fungi should be considered when planting moss farms and cultivating crops in close proximity to each other or when applying biological control agents containing Trichoderma species to green roofs. Furthermore, these results may encourage the use of the Physcomitrella mutant collection to identify candidate genes for signaling pathways to elucidate the molecular mechanisms underlying the defense responses of mosses.
  • Pesonen, Maiju (Natural Resources Institute Finland (Luke), 2020)
    The decrease in the dairy cattle population observed in recent years threatens to reduce the level of beef production. Although the number of beef cows has increased by 20% over the last 10 years, there is a clear discrepancy between the demand for and supply of domestic beef. Consequently, slaughterhouse pricing favours heavy carcasses and the average carcass weights of slaughtered animals have increased in recent years. There is a paucity of information on the effects of the breed on the performance, carcass characteristics and meat quality of beef breed bulls raised to heavy carcass weights. The first aim of this thesis was to evaluate the growth performance, carcass traits and meat quality of different beef breeds in the Finnish beef cattle population. The second aim was to evaluate the potential for improvement of carcass and meat quality traits through crossbreeding compared to purebred animals. The third objective was to evaluate carcass fat scores in relation to carcass weights in different breed groups. In addition, the effects of the proportion of concentrates and rapeseed meal (RSM) supplementation on animal performance, carcass characteristics and meat quality parameters were determined for Hereford (Hf) and Charolais (Ch) bulls. To achieve these aims five experiments were carried out. The objectives of the first experiment in which Hf and Ch bulls were offered grass silage-based diets, were to determine the effects on the performance, carcass traits and meat quality of the proportion of concentrate in the diet, and the inclusion of RSM in a barley-based concentrate. The objective of the second and third experiments were to study performance and meat quality of purebred Hf, Ch bulls and Hf × Ch crossbred bulls and Angus (Ab) and Limousin (Li) bulls and Ab × Li crossbred bulls which were offered grass silage-grain-based rations and raised to heavy carcass weights. The objective of the fourth experiment was to determine the growth and carcass traits of beef breed bulls and heifers. The data collected from Finnish slaughterhouses. The objective of the fifth experiment was to study the potential for improvement in the gain and carcass traits through Ab × beef breed crossbreeding compared to purebred Ab bulls and through Hereford Hf × beef breed crossbreeding compared to purebred Hf bulls. Continental breeds tended to have carcass traits that suit the Finnish beef production system well under the current Finnish feeding management approach. British breeds produced more intramuscular fat in the meat and have a higher sensory quality compared to Continental breeds. The carcass traits of British breeds can be enhanced for the current market demand by crossbreeding British breed dams with Continental breeds. The grass silage-grain-based diet suited beef breeds well for growing and finishing diets. The concentrate level can be reduced for British breeds. Continental breeds will benefit from increased concentrate levels in the diet. Protein supplementation does not add any substantial advantages to the diet. Using protein supplements will increase the environmental impacts of beef production.
  • Silvennoinen, Kirsi (Helsingin yliopisto, 2020)
    The significance of food waste (FW) arises from its large environmental, economic and social impacts. Furthermore, it affects food security and is a matter of resource efficiency for sustainable food production. In a situation where the world population is growing and climate change is affecting food production, FW should be minimized, to ensure the future food supply and natural habitats. The aim of this thesis was to study FW in the Finnish food supply chain, in households, food services, the food industry and the retail sector. Even though FW is generated throughout the supply chain, the impacts are most significant at the end of the chain. That is why reducing FW in households and food services is especially important. In this thesis, FW amounts and types were studied in the food chain in addition to methods for measuring FW and means for reducing FW in households and food services. Diary studies were used for studying the FW in households and food services and in the retail and food industry sector surveys and interviews were used. Together 380 of households from different areas in Finland finished the two weeks study period. The amount, type and origin of avoidable food waste were investigated in 51 food service outlets, including schools, day-care centres, workplace canteens, cafes and petrol stations, restaurants and diners. The average annual FW was about 23 kg per person and 4–5% of the purchased food amount. The main discarded foodstuffs were vegetables (19%), home cooked food (18%) and milk products (15%). The main reasons for disposing of foodstuffs were spoilage, expiry of the best-before or use-by date and plate leftovers. Almost half of the food waste (40%) was still unspoiled at the time of discarding it. In food services the amount of FW varied depending on the outlet type and was about one-fifth of all food handled and prepared in the outlets. During the study period the most FW were generated in day-care centres (28%) and workplace and student canteens (25%). The findings also suggest that the significant origin of FW was serving waste because of food overproduction for buffet lines. Suitable and appropriate measurement methods for monitoring FW are necessary for reducing FW amounts and following trends in FW. The most suitable method varies depending the sector and the data requirements. Besides FW data, also data about the food purchased or produced is needed for analyses and discussion.
  • Lai, Tin-Yu (Helsingin yliopisto, 2020)
    Ecosystem-based management is necessary for management of marine ecosystems because they are affected by multiple impacts, and some synergistic effects or conflicts may exist among these impacts and the possible solutions. This thesis applies three different approaches to contribute to ecosystem-based management. First, this research develops a multispecies bio-economic model that is able to consider food web interactions, different types of fisheries, and the various economic benefits provided by multiple ecosystem services. The developed model focuses on a food web consisting of migratory fish (salmon; Salmo salar), mammalian predators (grey seals; Halichoerus grypus), and schooling fish (herring; Clupea harengus) in the Baltic Sea. Additionally, the included ecosystem services include both provisioning and non-market cultural services, such as ecosystem services for fisheries, recreation and the existence of the species. By applying optimization approaches, the developed model is used to examine fisheries management. Second, structural equation modelling is applied to explore the causal relationship among climate and environmental factors, fisheries, prey availability and competitors to the salmon population. The last applied approach was ecosystem accounting, which is able to reveal the economic implications of ecosystem changes and the use of ecosystem services by different economic sectors. A framework integrating the ecosystem services and accounting system is proposed with a marine case study. Furthermore, the developed multispecies bio-economic model is applied with different valuation approaches to value the marine ecosystem for ecosystem accounting. By applying different approaches, this thesis provides insight and recommendations for ecosystem-based management from various perspectives.
  • Zhou, Xuan (Helsingin yliopisto, 2020)
    Permafrost is prone to thawing under disturbances resulting from frequent wildfires in boreal forests due to climate change, increasing the risk of the release of carbon (C) from it. Although the decomposition of organic C is mainly determined by the activity of soil microorganisms, productions of pyrogenic material after fire may offset this process. To evaluate the C dynamics related to wildfire disturbance in permafrost regions, this study examined the postfire changes in soil organic matter (SOM) decomposition, and the microbial community composition and its potential functions during a > 100-year chronosequence of burnt boreal forests. Based on the kinetic theory, the temperature sensitivity of slowly decomposing SOM tends to be higher than that of easily decomposing SOM. Consistently, we found the decomposition of SOM in burnt surface soils containing less-decomposable SOM generated by fire, was more sensitive to temperature than that in old-growth forests. Fire also decreased the microbial biomass and the fungal-to-bacterial ratio of the surface soils. Despite this, soil heterotrophic respiration and the microbial C:N:P ratio in burnt forests remained similar level to that in old-growth forests regardless of the changing SOM quality and quantity. This suggests the notion of a lower microbial C use efficiency following a fire. Unexpectedly, permafrost thaw did not alter the microbial biomass and the fungal-to-bacterial ratio, but increased the microbial metabolic quotient. Illumina Miseq sequencing of bacterial 16S rDNA revealed that the bacterial community composition in recently burnt surface soils differed from it in old-growth forest soils. Permafrost thaw, however, showed little effect on the bacterial community composition. Bacterial communities of burnt surface-soil exhibited higher abundance of Ktedonobacteria (Chloroflexi) but lower abundance of Betaproteobacteria. Functional gene compositions (DNA-based) of the burnt surface soil differed from those of the unburnt ones; particularly for genes coding for C degradation and the nitrogen cycle. Yet, the difference in the frequency of genes responsible for C degradation between thawed and frozen permafrost was not statistically significant. This thesis provides further evidence for effects of wildfire on the microbial biomass, microbial community composition, and its potential functions on the C and N cycles in boreal permafrost regions. To estimate the real pattern of soil C cycles following a fire, we must understand how fire affects the metabolic processes of soil microorganisms.

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