Faculty of Agriculture and Forestry

 

Recent Submissions

  • Zhang, Teng (Helsingin yliopisto, 2021)
    Inflorescences are flower bearing structures that display remarkable diversity in plants. Their architecture, referring to the number and arrangement of flowers, is considered as a key attribute to the reproductive success of plants. Asteraceae is one of the largest plant families, and the evolutionary success of this family has been largely attributed to their showy inflorescence structure, the flower head (or capitulum). A flower head combines up to a thousand individual florets and numerous leaf-like bracts onto a single receptacle, and the overall structure superficially mimics a giant solitary flower. Geometrically, the individual florets are arranged in left and right turning spirals following the consecutive numbers of the Fibonacci sequence. Such a pattern has fascinated interdisciplinary researchers over centuries. Elaborating Gerbera hybrida as a study system, this thesis aims at elucidating the molecular mechanisms underlying three key aspects in the development of a flower head: the phyllotactic patterning, the inflorescence patterning, and the patterning of floral organs. This thesis first combined data from diverse microscopic methods with computational modeling and illustrated how the phyllotactic pattern is established during the growth of Gerbera flower heads. The patterning process was governed by the expansion and contraction of the organogenetic zone where new primordia arise. Earliest bract initia were found to pattern on a ‘naked’ head meristem, and to guide the emergence of Fibonacci spiral numbers. A critical character for the patterning process is the lateral displacement of auxin maxima pointing towards the older neighbor. Results from this thesis provided the first experimental basis for understanding how phyllotactic patterns are transited on a growing meristem. This thesis then demonstrated how flower meristem identity genes GhLFY and GhUFO are co-opted to regulate flower head development. While GhUFO acts as the master regulator of flower identity, GhLFY has evolved two novel functions to regulate the determinacy of inflorescence meristem and the early ray floret initiation. The results provided novel insights to explain how the flower head structures are evolved and diversified. This thesis lastly dissected functions of the SEPALLATA-like GRCDs in regulation of Gerbera flower and inflorescence development. In this study, the GRCDs were shown to have evolved specialized functions in regulating floral organ identities, among which, GRCD4 and GRCD5 are two indispensable regulators for petal development. Moreover, GRCD2 and GRCD7 show redundant functions at the inflorescence level maintaining their determinacy. The results provide an example on how gene duplications could lead to specialized and redundant functions in regulation of a highly elaborated inflorescence structure.
  • Pärnänen, Katariina (Helsingin yliopisto, 2021)
    Antibiotics were once miracle cures, but because of the spread of antibiotic resistance in bacteria, their effectiveness is threatened. Although antibiotics have only been produced industrially for 70 years, antibiotic-resistant bacteria are a threat to human health. The effects of antibiotic use pass on over generations, and resistance kills an estimated 214,000 infants a year. Antibiotic-resistant bacteria have also become widespread in the environment. In my dissertation, I used a microbial ecology perspective to study how the antibiotic resistance crisis manifests itself in humans (with a focus on mothers and infants) and in the environment. My main lines of research focused on selection pressures that shape bacterial communities and the effects of the spread of resistant bacteria. I studied the amounts of antibiotic resistance genes in different environments, utilizing methods based mainly on metagenomics. Mothers pass on antibiotic-resistant bacteria to their children. However, in my study, the resistance load of infants’ intestines was most affected by infant formula use. Infants who received formula had a significantly higher proportion of bacteria carrying resistance genes than exclusively breastfed infants. Surprisingly, formula use increased the intestinal resistance load more than the antibiotic regimens given to babies, which could not be shown to have an effect in my dissertation. Antibiotic selection pressure did not explain the number of resistance genes in the environmental samples I studied either. The results suggested that fecal contamination is almost always behind the resistance load observed in the environment. It was therefore interesting that the treated wastewater discharged from European wastewater treatment plants into the environment corresponded to the types of resistance of bacterial strains isolated from infected patients. The result suggests that inadequate wastewater treatment is part of the resistance problem in Europe as well, and not just in developing countries, and potentially increases the spread of antibiotic-resistant bacteria to humans. My work shows that the most effective ways to reduce resistance may not be intuitive. Bacterial spread may play a larger role than previously thought. Efficient waste treatment and exclusive breastfeeding may reduce the number of resistant bacteria in society, the environment, and young children more effectively than reducing the use of antibiotics.
  • Kudinov, Andrei (Helsingin yliopisto, 2021)
    Implementation of genomic evaluation is challenging for populations with limited data. The main objective of this thesis was to identify an approach to implement single-step genomic best linear unbiased prediction (ssGBLUP) in a small-scale dairy cattle population. In particular, the aims were to predict GEBVs by ssGBLUP using local genotypes, enhance the reliability of prediction by incorporating data from an external breeding population, and implement the metafounder approach. The first objective of this study was to develop state-of-the-art BLUP Animal Model for Holstein (HOL) and Russian Black & White cattle of Leningrad region (LR, Russia). The traits of focus were milk, fat, and protein yield. The data used to develop the first (FLM) and multiple (MLM) lactation models included 320,633 repeated 305d records from 49 herds. The heritability estimates for milk, fat, and protein yield were 0.24, 0.20, and 0.20 for FLM and 0.18, 0.19, and 0.18 for MLM. For cows born between 2000 and 2016, MLM estimated an annual average genetic gain of 56 kg, 1.84 kg, and 1.62 kg for milk, fat, and protein yield, respectively. The second objective was to implement ssGBLUP for LR using a set of local genotyped animals. Genomic data were available from 1080 cows and 427 bulls. MLM was improved by adding a herd by sire interaction random effect. Milk yield cross-validation analysis showed a validation reliability (R^2) of 0.21 and 0.38 for bulls and cows, respectively. The R^2 values for fat yield for bulls and cows were 0.17 and 0.41. The third objective was to enhance the LR ssGBLUP prediction by using external DFS (Denmark, Finland, and Sweden) HOL genomic and pedigree information. The inclusion of DFS genotypes did not change the milk yield R^2 for bulls but slightly decreased it for cows (0.38 to 0.36). For fat yield, R^2 increased from 0.17 to 0.18 for bulls and decreased from 0.41 to 0.34 for cows. In analysis of milk yield, the highest R^2 was realized in the ssGBLUP model simultaneously using genomic and phenotypic data from both LR and DFS: 0.30 for bulls and 0.42 for cows. In fat yield, no improvement in R^2 was observed (0.18) for bulls and an unexpected decrease was observed for cows (0.21). The fourth objective was to implement the metafounder (MF) approach in ssGBLUP. The data were a subset of Finnish Red dairy cattle, including 112,479 cows with first lactation 305d milk records. Genomic data were obtained from 3,571 bulls and 16,186 cows. MF covariance matrix (Γ) was created using base population allele frequencies estimated using a one-generation pedigree for each animal. After the estimation, markers were filtered with a minor allele frequency criterion of 0.05. Diagonal elements of the genomic relationship matrix had a lower correlation with the regular pedigree relationship matrix (A; 0.66) than with the one using Γ (A^Γ; 0.76). Validation reliability of milk GEBVs in bulls increased by 0.04 (from 0.27 to 0.31) when using the MF approach. In cows the gain was 0.01 (from 0.36 to 0.37).
  • Viholainen, Noora (Helsingin yliopisto, 2021)
    This dissertation examines current collaborative practices in wooden multistorey construction (WMC) projects through a business ecosystem approach to detect effective and ineffective practices when working with novel wooden materials and gaining knowledge of them. Furthermore, it deepens our understanding of citizen perceptions and homeowner experiences towards WMC, to ensure that professionals are able to construct buildings that are not only profitable, but also appreciated by end-users and functional in daily use. Qualitative means are used to provide an in-depth view of the matters. The findings reveal that while construction projects are essentially collaborative efforts, the novelty of WMC materials and methods requires increased communication and learning between the business ecosystem participants. The keystone of a business ecosystem has a fundamental role in enabling deeper, long-term commitment between participants through procurement practices and meetings. These allow participants to work towards a common goal and to accumulate knowledge of wooden construction also between projects. Feedback processes should be improved between the participants, but homeowner experiences should also be utilized more efficiently. The results imply that while the business ecosystem approach provides a usable lens to study collaboration in WMC projects, it should not be seen as a static system concentrating on the design and construction phases, but one that evolves throughout a building’s life cycle, incorporating end-users as the ecosystem keystones when moving to the use phase of the building. Furthermore, the results support previous literature in that end-users appreciate soft aspects of wood material, such as aesthetics and ambiance, while durability and maintenance needs create concerns. However, the qualitative approach used in this study reveals that some aspects are multifaceted, carrying both positive and negative meanings for the end-users. Homeowner experiences indicate the importance of the everyday usability of home materials. Furthermore, the ‘liveliness’ of the wooden material seemed to surprise some of the homeowners, indicating that they are more familiar with other urban construction materials. Communication with end-users should therefore be improved to decrease concerns, but also to inform about the material’s practical benefits such as pleasant soundscapes.
  • Pirttioja, Nina (Helsingin yliopisto, 2021)
    The agriculture sector is facing considerable challenges in ensuring food security under projected changes in climate and pressures to reduce its environmental impacts, among others. With changes in growing season and local growing conditions already being observed, adaptation is a key factor in aiming towards climate-smart, sustainable agriculture. Process-based crop models offer a tool for understanding complex interactions associated with crop, environment and management actions, and quantifying their impacts on various outputs. In the face of uncertainties associated with impact estimates, risk assessment has become an essential part of adaptation planning. This study explored the use of a “scenario-neutral” approach for informing risk assessments in the context of crop production. Its main motivation was to examine novel insights offered by the approach for characterising uncertainties associated with modelled impacts compared to conventional scenario-based approaches, where impact estimates are tied to a given scenario. The approach utilises impact response surfaces (IRSs) to depict simulated period-mean sensitivities of cereal yields to systematic changes in baseline (1981–2010) temperature and precipitation. The analysis focused on sites in Finland, Germany and Spain, across a transect of contrasting environmental zones that hence facilitated an examination of the effect of site-specific growing conditions on the impacts of projected changes on cereal yields. The research encompassed a multi-model IRS study involving 26 crop models for wheat as well as an IRS study employing a single model for barley. In addition to analysing median responses of the model ensemble across the transect, approaches were developed for classifying and interpreting individual model responses. By combining IRSs with projections of climate interpreted probabilistically, likelihood of crop yield shortfall was estimated and its evolution throughout the 21st century visualised. This was estimated with a single crop model WOFOST for spring barley in Finland. Effects of adaptation on yield were considered through adapted sowing and cultivar choice. Evolution of future atmospheric carbon dioxide concentration [CO2] defined by representative concentration pathways also used for climate projections (RCP4.5 and RCP8.5) was also considered when estimating likelihoods. With the multi-model ensemble study of wheat yield sensitivities [CO2] was fixed at 360 ppm. Simulated cereal yields were found to decline with warming and drying and increase with higher precipitation. The yield response in Finland was dominated by temperature. Precipitation change dominated the response of spring wheat in Spain, while the response was more mixed in Germany. The multi-model ensemble median response offered a consensus view of impact sensitivities, with individual model behaviour occasionally departing markedly from the average. IRS patterns across the multi-model ensemble showed greater similarity in the pattern of modelled yield responses for Germany in comparison to Finland and Spain. Similarity in patterns was also associated with models of related genealogy. With respect to the effectiveness of tested adaptation options, results suggest that combining cultivars with short pre- and long post-anthesis phases with earlier sowing, offers most promise for obtaining the largest yield gains and smallest likelihoods of yield shortfall under future scenarios. Higher levels of [CO2] generally compensate for yield losses with warming, with the effect emphasised with the biggest increases in temperature. IRSs offer a valid alternative to conventional scenario-based approaches with many advantages for presenting and analysing results. IRSs can assist in model testing, comparison of results across models, studies and sectors and examination of various statistical characteristics of the response, greatly facilitated by the possibility to visually depict impact sensitivities in consistent ways. Use of multi-model ensembles with respect to both climate projections and crop impacts increases the robustness of results and provides information on the uncertainties around the yield estimates. The approach for estimating and visualising impact likelihoods provides improved understanding and transparency of concepts behind the likelihood estimates.
  • Savela-Huovinen, Ulriikka (Helsingin yliopisto, 2021)
    The study focused on sensory evaluation professionals and the aim was to gain an understanding of the competencies and practices required in their work in Finnish food industry. In addition, sensory professionals’ assessments of how digitalization can change the evaluation practices were explored. The specific research questions were: 1) What kind of competencies did sensory evaluation professionals report to need in their work? 2) What kinds of knowledge-creating practices did the professionals report? and 3) How did the professionals perceive the influences of using digital technologies on certain aspects of sensory evaluation practices and sensory consumer testing? Altogether 114 sensory professionals from Finnish food companies and universities participated in the study. The first sub-study (I) examined the daily practices of sensory professionals and highlighted the perspective of competencies and contexts. The second sub-study (II) examined the routines and knowledge-creating practices at work, as well as the perceptions of the effects of digitalization on the work. The third sub-study (III) examined how did the sensory professionals perceive the possibilities of utilizing facial expression analysis in sensory evaluation work. According to the results, assessors learn extensively from each other in collaborative interactional and knowledge creation contexts. Learning and development takes place in various practical sensory evaluation assessments, test situations, quality control, and by learning from consumer feedback. Individual and collaborative knowledge-creating practices can be demonstrated in industrial sensory evaluation work. Sensory professionals described and identified practices relevant for creating knowledge. According to sensory professionals, product-specific competencies develop only through several years of long-term training, in which collaboration with other colleagues and product knowledge are key elements. According to the survey and interview results, professionals perceived that their work would change as a result of digitalization and the introduction of new methods. The research results showed that product-oriented assessment methods are accompanied by the tasks related to the management of various digital materials collected from consumer tests. New jobs require sensory professionals to have related digital competencies and understanding of related ethical responsibilities.
  • Wasonga, Daniel (Helsingin yliopisto, 2021)
    Cassava (Manihot esculenta Crantz) is a staple food for millions of people in the tropics, providing high energy and nutritional value. Problems associated with cassava in the arid tropics are low yield, high cyanide concentration, and low mineral and vitamin A availability in leaves and roots. These factors hinder the utilization of cassava greatly and are highly influenced by the plant water status and potassium (K) availability in the growth environment. The productivity of cassava in such environments could be improved using irrigation strategies not based on full crop water requirements, such as deficit irrigation combined with K nutrition to ensure sustainable quantity and quality production. Additionally, employing systems that can allow non-destructive estimation of plant performance, such as the use of plant imaging techniques, could provide early information on plant performance, which would facilitate phenotyping, as well as assist in the mitigation of abiotic challenges in cassava production. This study investigated how irrigation water, K fertigation and their interactions affect the growth responses of biofortified cassava during the early growth phase. It was also investigated whether K fertigation could improve the nutritional and reduce the anti-nutritional qualities of biofortified cassava growing under typical conditions of water deficit. The ability to use red-green-blue (RGB) and multispectral sensors to detect the effects of water deficit and low K in cassava, and whether the crop quality changes due to low moisture and low K could be observed from the images, were also examined. Pot experiments were conducted at early developmental stages of cassava under controlled greenhouse conditions at the University of Helsinki. Young biofortified cassava plants were established using cuttings. The plants were subjected to three irrigation treatments (30%, 60%, 100% pot capacity) that were split into five K (0.01 mM, 1 mM, 4 mM, 16 mM, 32 mM) application rates beginning 30 days after planting (DAP) and ended at 90 DAP, when plants were harvested. Irrigation treatments and K application rates significantly affected leaf water potential, leaf osmotic potential, net photosynthesis, stomatal conductance, leaf temperature, leaf chlorophyll, water usage, plant leaf area, plant height, tuber number and whole-plant biomass. The interaction was also statistically significant for these properties. Irrigation treatments and K application rates also affected leaf turgor, but the interaction was not statistically significant. Irrigation at 30% together with 16 mM K lowered the leaf water potential by 69%, leaf osmotic potential by 41%, net photosynthesis by 35%, stomatal conductance by 41%, water usage by 50%, leaf area by 17%, and whole-plant dry mass by 41%, compared with fully irrigated plants. Lowering the K application rate below 16 mM reduced the values further. Most importantly, the growth was decreased least when irrigation was decreased to 60% together with 16 mM K, compared with optimal applications. The combined effect of irrigation treatments and K applications was statistically significant for starch, energy, minerals, total carotenoids, and cyanide, but the interaction was not statistically significant for dietary fibre and crude protein in the leaves and roots. In the leaves and roots, water deficit and lower K applications inhibited starch, carotenoids, crude protein, and fibre synthesis. Water deficit interrupted the uptake of minerals by the cassava roots from the soil and ultimately to the leaves. Improved uptake of calcium, phosphorous, magnesium, zinc, iron, sulphur, and chloride to the leaves was recorded with increased K application regardless of water deficit. K application also mitigated the effect of water deficit at 30% irrigation. Crude protein, carotenoids, and minerals were revealed to be more abundant in the leaves than in the roots, while the inverse was the case for starch content and iron. Cyanide was diminished in the leaves and roots of the cassava with increases in both irrigation and K application rates. Full irrigation (100%) with 16 mM K application produced the highest nutritional quality and the least cyanide concentration. Also, 16 mM K significantly improved the nutritional qualities and diminished the cyanide concentration irrespective of the irrigation treatment. High estimation accuracy (R2 = 0.90) for biomass, chlorophyll, and net photosynthesis were recorded. The estimated leaf area associated strongly (R = 0.98) with the measured leaf area. The estimated biomass also associated strongly with the measured biomass. Starch, energy, total carotenoids, and cyanide were estimated reasonably (R2 > 0.80) and showed strong correlations with the most of spectral indices. The estimation accuracy for all mineral elements was low, and weak relationships existed between the mineral elements and the spectral indices. The regression models identified normalized difference vegetation index, green area index, and simple ratio index as the best estimators of growth and key nutritional traits in cassava. Moreover, irrigation at 30% together with 0.01 mM K reduced all the index values but increased crop senescence index. Regardless of water deficit, increasing K application rate to 16 mM resulted in high values for all the spectral indices but low senescence index. In conclusion, adjusting K fertigation rates in combination with deficit irrigation may improve the growth and dietary quality of young cassava, and reduce cyanide concentration. Findings from this work can be utilized as a foundation to develop agronomic management practices involving K application for cassava growing in water-limited environments. The study also shows that RGB and multispectral sensors can be used to provide indirect measurements of growth and key nutritional traits in cassava, thus representing a tool that breeders may use to facilitate evaluation of cultivars, especially in the developing areas. Information from imaging data may also be used to facilitate corrective measures to avert stress, such as the decision to irrigate or apply fertilizers. Nonetheless, laboratory analysis of plant samples should support sensor estimates, especially under field conditions, when all possible factors affecting plant growth are difficult to forecast. Future studies could place emphasis on field conditions with multiple cassava cultivars and employ different imaging techniques.
  • Njoghomi, Elifuraha Elisha (Helsingin yliopisto, 2021)
    This research focuses on stand dynamics and ecological recovery in miombo woodlands, Morogoro, Tanzania. The study uses the Kitulangalo Permanent Sample Plots (PSPs) to analyse tree species’ site-specific growth, regeneration dynamics, and stand development using empirical and modeling approaches. The high number of tree species in miombo necessitated the formulation of three species groups involving 1) trees that grow relatively rapidly to be dominants in top canopy layers 2) trees that stay mainly in the lower and middle canopy levels and 3) trees that grow slowly but persistently and may eventually rise to dominant and codominant canopy positions applied in studies I and III. Study III also applies three harvesting alternatives, which align with the recommended harvesting practices for these woodlands. Diameter increment varied with the change in basal area growth across species groups, reaching a maximum of 3.2 cm (group 1) during 2008-2016. Density-dependent mortality and ingrowth also varied with species group as higher mortality rates dominated the lower and middle canopy layers due to asymmetrical competitions. Fencing the plots prompted thick grass cover. The drop in the total number of regeneration stems and the simultaneous increase in the number of main stems in fenced areas and dense plots indicated a self-thinning process induced by competition. This is linked to multi-stem regeneration undergoing a morphological transformation into single-stem saplings (main stems) and eventually becoming small trees. Harvesting intensity, density-dependent mortality, and ingrowth regulated stand basal area and therefore stand growth and development during the simulation. Stand structural development was dominated by species groups 1 and 2, indicating sustainability in species composition and structures. Stand development was affected by the addition of new stems of each species in each simulation year. Miombo stands have demonstrated the potential to attain a steady-state condition over the medium-term under-regulated stand conditions and silvicultural treatments. The developed models, treatments, and harvesting alternatives may be limited in application to Kitulangalo and similar lowland miombo woodlands in Tanzania. Future studies concerning stand conditions, silvicultural treatments, and harvesting alternatives are vital for a better understanding of stand dynamics in miombo woodlands in Tanzania. Keywords: Forest disturbance, tree growth and stand dynamics, regeneration dynamics, silvicultural treatment, harvesting alternative, miombo woodlands
  • Haikka, Hanna (Helsingin yliopisto, 2021)
    The aim of this study was to detect usability of genomic prediction for different breeding dilemmas. In order to achieve this aim, breeding data sets from oat and barley were used in the study. The studied lines were genotyped with genome-wide markers. Meanwhile, phenotypes were collected from multiple years and locations of historical breeding data. Together, the data of the line genotypic and phenotypic information formed the training population used in the analysis. The separate studies concerned genomic prediction, genome-wide association study (GWAS) and analysis on genotype by environment (GE) interaction. The studies had in common that they present ‘difficult’ topics within the breeding process. The original publication I concentrated on improving grain yield prediction for oat and barley. Grain yield presents one of the most important traits in breeding, but has low predictability due to low heritability. The prediction of genomic estimated breeding values (GEBVs) was improved by using multi-trait prediction. For this purpose, grain yield was predicted simultaneously with correlated traits. In addition, benefit of trait-assisted prediction was examined. In conclusion for oat and barley, prediction of grain yield was improved by 4% and 9% with multi-trait prediction, and by 9-14% and 11-28% with trait-assisted prediction compared to prediction of grain yield alone, respectively. The original publication II focused on Fusarium head blight (FHB) resistance in oat. FHB resistance is a troublesome trait to breed, since the disease cannot be reliably scored visually, but extensive laboratory analysis is needed to obtain resistance phenotypes. In addition, FHB resistance consists of multiple components. In the study, the correlations between FHB resistance related traits were high. Much lower correlations were seen between FHB resistance related and agronomic traits. No significant associations between FHB related traits and genetic markers were discovered with reasonable correction of population structure and genetic relationship between the studied oat lines. For this reason, using genome-wide marker information to promote resistance breeding should be done solely with genomic selection (GS), where all the marker effects are used to enrich resistance alleles within the breeding population. The original publication III explored the extent of GE interaction within breeding data sets of oat and barley. At first, the genetic correlations between trial locations within year were calculated and used to compute mean across the years. The correlations suggested that data set of oat was not as sufficient as the data set for barley to explore the quantity of GE interaction. The second step of the analysis contained genomic prediction with six different models. The prediction models contained effects due to lines, genetic, environmental covariates, GE interaction and genotype by environmental covariates interaction. The prediction accuracy was increased for both crops when GE interaction was added into the prediction model. The results from the analysis imply that GE interaction exists within the breeding data sets, and should be taken into account upon prediction. All of the conducted studies proved the usability of genomic prediction in solving principal questions in the breeding process. The studies improved prediction of central traits simultaneously enabling the prediction in the early breeding generations, and showed the significance of GE interaction, and most of all, showed that historical breeding data can be used to predict the important traits. These studies present tools for practical breeding in order to meet the demand to accelerate crop improvement.
  • Tuure, Juuso (Helsingin yliopisto, 2021)
    Water scarcity is globally a key reason for crop yield losses. Difficulties in efficient utilization of the total available precipitation cause yield limitations and even total crop failure at rainfed dryland farms. This study assessed two potentially available measures to improve the water balance of dryland agriculture; water recovery through passive dew collection and soil mulching with plant residue. Dew collection field experiments were conducted to evaluate the effectiveness of various plastic materials in dew collection in dryland conditions. The planar dew collectors were of the standard type: a 1 m2 surface tilted at 30◦ in respect to the horizontal. Dew yields were measured daily over a one-year period. The condensing surface temperatures and the meteorological conditions were monitored continuously, to calculate potential dew output. A laboratory method was prepared and tested for evaluating the attributes affecting dew condensation and droplet flow. The condensing surfaces were cooled below dewpoint by utilizing Peltier elements in controlled conditions. Dew yields measured in laboratory conditions were compared with calculated dew outputs, and with dew yields measured in field conditions. Dew occurred throughout the year, even through the dry seasons, and may be considered a small but reliable source of water. Annual dew yields were < 8% of the annual precipitation (322 mm). No significant differences were found between the tested materials. Clear skies, calm winds (0.5–2.5 m s-1), and conditions with dew point close to air temperature (Tdew ≈ Tair) favor dew condensation. Placement in the field affects the airflow characteristics at the condensing surfaces and ultimately the collected dew quantities, thus attention should be paid to the placement of the dew collectors in the field. Based on our results, a more comprehensive laboratory evaluation regime, with specific design and measurements of the airflow characteristics is needed to draw valid conclusions on the differences between the plastic foils. Mulching with plant residue was studied by measuring soil volumetric water content in vertical profiles in bare and plant residue-covered soil during a 100-day period. A one-dimensional model based on Richard’s equation was used to predict the effect of mulch over a two-year period. Compared with bare soil, mulching prolonged the time when continuously measured soil moisture content exceeded the water stress limit of maize. The predicted water-conserving effect increased with mulch thickness. However, plant residue mulch degrades naturally and the availability and competitive uses of plant residues may limit the thickness of the mulch layer. A mulch layer with a thickness of > 1 cm brought clear improvements to the soil moisture conditions and resilience against dry spells compared with bare soil. The presented models were capable of estimating the cumulative dew condensation and soil moisture behavior satisfactorily over time. For further development of the dew condensation model, more specific airflow measurements are needed for calculating the mass transfer for more accurate predictions of nightly dew quantities. This study touched upon the combined effect of irrigation with dew water and mulching on by using modeling to predict the effects on soil moisture. The results indicated that mulching improves the usability of irrigational water recovered from dew by reducing evaporation. The effect increases with layer thickness. Future research steps could include the quantification of the presented water-conserving measures on actual crop yields, especially the combined effect.
  • Silventoinen, Pia (Helsingin yliopisto, 2021)
    The agro-food industry generates annually substantial amounts of side streams, resulting in the loss of high-quality protein and dietary fibre, whereas their incorporation into the food chain would positively contribute to resource sufficiency and healthier diets. However, plant-based ingredients, especially proteins, typically deliver limited performance in certain food applications, such as beverages and spoonable products, when compared with their animal-based counterparts. Therefore, fractionation and functionalisation techniques are investigated and applied to improve the applicability of the plant-origin ingredients in a wider range of food matrices where they can offer alternatives to animal-based ingredients. Dry fractionation provides a sustainable and gentle processing technology, which allows the production of multicomponent hybrid-ingredients, enriched in protein but also containing considerable amounts of dietary fibre or starch, depending on the raw material. The aim of the current work was to investigate the use of dry fractionation, more specifically, dry milling and air classification, for increasing the protein content of cereal side streams, namely, wheat, rice and rye brans, and the barley endosperm fraction. In addition, the objective was to understand the factors affecting the technological functionality and applicability of the protein-enriched ingredients in the relevant food matrices. To facilitate a more efficient fractionation, pre-treatments, including defatting with supercritical carbon dioxide (SC-CO2) for rice bran, moisture removal for wheat and rye brans and mixing with a flow aid for the barley endosperm fraction, were elucidated. The technological functionality of the protein-enriched fractions was examined, and bioprocessing and physical processing approaches for improving the ingredient applicability in high-moisture food systems were investigated with rice and barley fractions. This study revealed that the fat removal, drying and use of flowability aids were effective in enhancing dry fractionation by improving the processability, particle size reduction and dispersability of rice bran, wheat and rye brans, and the barley endosperm fraction, respectively. Pin disc milling and air classification of a SC-CO2-extracted rice bran increased the protein content from 18.5 to 25.7% with 38.0% protein separation efficiency (PSE). Alternatively, a two-step air classification of the defatted rice bran allowed to reach a slightly higher protein content (27.4%) with lower PSE (20.2%) compared with the one-step air classification approach. Air classification of the dried and pin disc-milled wheat and rye brans increased the protein content from 16.4 and 14.7%, respectively, to 30.9 and 30.7%, with PSE of 18.0 and 26.9%. Additionally, soluble-to-insoluble dietary fibre ratios were increased and phytic acid was considerably enriched in bran fractionations. The maximum protein content reached by air classification from the barley endosperm fraction, initially containing 80.0% starch and 8.3% protein, was 28.3% with 21.7% PSE, while reaching a lower protein enrichment level of 22.3% allowed obtaining PSE of 59.4%. The protein-enriched fractions, especially those from rice and wheat, exhibited higher protein solubility than the raw material brans, presumably due to the enrichment of albumin and globulin proteins from the aleurone during air classification, which was also indicated by an altered protein profile and the co-enrichment of phytic acid. When the ultra-fine milling of wheat and rye brans was explored as an alternative to fractionation, the formation of damaged starch and lowered protein solubility were observed. The protein-enriched brans and the ultra-finely milled brans both showed improved dispersion stabilities, whereas pasting viscosities, and water and oil binding capacities were lower for the hybrid ingredients compared with the pin disc-milled raw materials. The protein-enriched fraction from barley, on the other hand, exhibited low protein solubility and limited techno-functional properties. The applicability of the protein-enriched fractions in high-moisture food model systems was tested after ingredient modifications via enzyme treatment, ultrasonication and pH shifting. Phytase treatment of the protein-enriched rice bran fraction improved the behaviour of the ingredient in heat-induced gelation, especially under alkaline conditions. For the protein-enriched barley fraction, ultrasound treatment with or without pH shifting reduced particle size; improved colloidal stability at pH 3, 7 and 9; and increased protein solubility, especially at pH 9. To conclude, dry fractionation of cereal side streams allowed protein enrichment with a concurrent increase in the soluble-to-insoluble dietary fibre ratios of the brans and considerable reduction in the starch content of the barley endosperm fraction. Additionally, this thesis demonstrated for the first time that cereal side stream-derived, protein-enriched hybrid ingredients exhibit improved technological functionalities that can be further enhanced via enzymatic or physical processes that affect, for example, their gelation and dispersion stability. The bioprocessed protein-enriched rice bran fraction could find potential use as a raw material in spoonable food products delivering a good amount of protein and dietary fibre and allowing the use of the nutritional claim that the food is a ‘source of fibre’. The ultrasound-treated barley protein ingredients, on the other hand, should be further studied in the manufacturing of plant-based milk substitutes. In general, these improved ingredient properties suggest the possibility of developing novel side stream-based food ingredients with increased nutritional and technological qualities that simultaneously contribute positively to raw material resource sufficiency.
  • Salin, Siru (Helsingin yliopisto, 2020)
    The research documented in publications I-IV involved studies in dry, late-pregnant Ayrshire dairy cows on grass silage (GS) based diets (I-IV). The principal aim was to investigate the effect of prepartal plasma non-esterified fatty acids (NEFA) level (I) and the effect of prepartal dietary energy intake (II-IV) on the development of insulin resistance (IR) during late pregnancy (I-IV) and changes in insulin resistance in early lactation (II-IV). Detailed, extensive physiological studies were conducted to understand the mechanisms underlying the development of maternal insulin resistance and to investigate the impact of changes in dietary energy level and subsequent changes in plasma NEFA concentration prepartum. The insulin resistance was assessed by interpretation of data from intravenous glucose tolerance test (IVGTT) with minimal model (MM) approach (I-III) and by insulin challenge (IC; I, II) data. Besides insulin resistance, also the impact of prepartal energy intake on metabolic adaptations, tissue deposition and mobilisation as well as dry matter intake (DMI) and lactational performance were investigated in publications III and IV. In publication I, the key objective was to evaluate the effects of increment of plasma NEFA concentration, typically observed during the last weeks of pregnancy and in early weeks of lactation in dairy cows, on glucose tolerance and responsiveness or sensitivity to insulin as assessed by IVGTT and IC. The greater NEFA levels were achieved by abomasal infusion of tallow (TAL) or camelina oil (CAM). Compared with water infusion (CON), infusion of lipids increased basal plasma NEFA concentrations by around 50%, to an equal level than what was found in dairy cows 2 to 1 weeks prepartum on GS-based diets (II-IV). Elevation of plasma NEFA concentration impaired glucose clearance and decreased insulin secretion during metabolic challenges. These data suggest that elevated plasma NEFA concentrations impaired whole-body insulin responsiveness and sensitivity in dry cows in late pregnancy. As assessed by MM indices, both the disposition and the insulin sensitivity indices were greater after CAM than TAL infusion during IVGTT. Compared with TAL infusion, CAM had an insulin-sensitizing effect which was most likely caused by alterations in plasma profiles of major long-chain fatty acid (FA) groups. A 50% increment in the percentage of polyunsaturated FA (C18:2 and C18:3) and a similar decrease in the percentage of monounsaturated FA (C16:1 and C18:1) was found in plasma FA profiles after CAM infusion when compared with TAL. In publication II, the dietary effects on insulin resistance were assessed not only by the level of energy intake but also by comparing tissue responses to glucose and insulin in late pregnancy vs. early lactation. Compared with controlled energy intake (CEI), the effect of prepartal overfeeding and gradual restriction of energy (HEI) had a minor effect on whole-body insulin resistance during the transition period. An attenuated prepartal NEFA response to endogenous insulin was found in HEI cows suggesting a more refractory adipose tissue to insulin than in CEI. After parturition, this effect was reversed. Across the dietary treatments, both basal and stimulated insulin concentration decreased after parturition as a result of a lower response to a similar secretory stimulus than before parturition and due to increased clearance of insulin postpartum. Compared with prepartal IVGTT, glucose disposal was enhanced postpartum across the dietary treatments. A hyperbolic relationship denoted as the disposition index (DI) was observed during the IVGTT. Compared with prepartal glucose and insulin dynamics across the diets, the MM indices point to increased insulin resistance shortly before than shortly after parturition. However, low insulin concentration is the major factor regulating the use of glucose by peripheral tissues in early lactation. The lack of dietary effect on whole-body insulin resistance in publication II was most likely due to minor dietary effect on tissue accretion between treatment groups, although the lower prepartal plasma NEFA concentration in HEI than in CEI cows suggests enhanced lipid deposition in adipose tissue before parturition, facilitated by higher plasma insulin (IV). No dietary effect on plasma hormone and metabolite concentrations or total DMI was found after parturition. High energy intake during the dry period tended to decrease milk yield after calving (IV). In publication III easily applicable diets suitable for loose housing systems were compared. An ad libitum allowance of GS (HEI) induced a more pronounced BW and BCS change prepartum when compared with a GS-diet diluted with wheat straw (CEI). HEI cows demonstrated a compensatory insulin response to glucose in prepartal IVGTT which preserved glucose tolerance of peripheral tissues. The HEI diet reduced and delayed NEFA suppression suggesting decreased insulin sensitivity and responsiveness in adipose tissue prepartum. The high NDF-content in CEI diet probably decreased ruminal propionic acid production as reflected by lower prepartal glucose and insulin CEI cows. Prepartal energy level did not affect metabolic flexibility of transition dairy cows as assessed by the absence of dietary effect on mobilisation of body reserves, plasma metabolites and hormones, and DMI after calving, whereas milk yield was greater from week 5 onward in HEI than in CEI. The moderate negative effects of gradual restriction of prepartal energy and dilution of energy by mixing GS with wheat straw on early lactation production response demonstrated that these feeding practices were not optimal for transition dairy cows. A moderate or ad libitum overfeeding affected peripheral insulin resistance in the level of prepartal lipid metabolism, while ad libitum overfeeding of GS induced changes in prepartal glucose metabolism as well. Both the difference in energy intake and the composition of the diet contributed to the observed effects on glucose and NEFA dynamics orchestrated via changes in insulin concentration in the transition period. Keywords: dairy cow, transition period, grass silage, energy intake, peripheral insulin resistance, adipose tissue lipolysis, plasma hormone and metabolite, milk yield, lipid infusion, plasma NEFA, minimal model
  • Ahlberg, Sara (Helsingin yliopisto, 2020)
    Aflatoxins continue to be a food safety problem globally, especially in developing regions. Prevalent food contaminating aflatoxins are B1 (AFB1) and M1 (AFM1). These are human carcinogens and have potentially severe health impacts. Almost all (99.5 %) milk samples from Nairobi were contaminated with AFM1, highlighting the urgent need to create functional solutions to improve food safety. Based on the aflatoxin levels and milk consumption, risks were calculated: cancer risk caused by AFM1 was lower among consumers purchasing from formal markets (0.003 cases per 100,000) than for low-income consumers (0.006 cases per 100,000) purchasing from informal markets. Overall cancer risk (0.004 cases per 100,000) from AFM1 alone was low. Because of AFM1 in milk, 2.1 % of children below three years in middle-income families, and 2.4 % in low-income families, could be stunted. Overall, 2.7 % of children could hypothetically be stunted due to AFM1 exposure from milk. Based on these results AFM1 levels found in milk could contribute to an average of -0.340 height for age z-score reduction in growth. The exposure to AFM1 from milk is 46 ng/day on average, but children bear higher exposure of 3.5 ng/kg bodyweight (bw)/day compared with adults, at 0.8 ng/kg bw/day. Aflatoxins are produced by Aspergillus flavus fungus, which is prevalent in soils. Certain strains of lactic acid bacteria (LAB) have been reported inhibiting fungal growth. 171 LAB strains were tested against aflatoxin producing A. flavus fungi. The three LAB strains showing the highest antifungal activity were identified as Lactobacillus plantarum. None of the strains was able to completely inhibit fungal growth under conditions favorable for fungi and suboptimal for LAB. The three indigenous LAB Lactobacillus strains and one Lactococcus strains were tested for their AFM1 binding abilities in different conditions and after different treatments along with two reference Lactobacillus strains. The binding of AFM1 by LAB strains varied between 11 to 100 % in the biocontrol solution analysis, being approximately at the level of 40 % throughout the analysis sets. A significant amount of effort and resources have been invested in an attempt to control aflatoxins. However, these efforts have not substantially decreased the prevalence nor dietary exposure to aflatoxins in developing countries. The growth reduction of aflatoxin producing fungi with LAB could be one potential option, but there are still major issues to solve prior to any practical applications. A different approach to control aflatoxins suggesting the usage of binding agents in foods and lactic acid bacteria (LAB) have been studied extensively for this purpose. However, when assessing the results comprehensively and reviewing the practicality and ethics of use, risks are evident, and concerns arise. In conclusion, there are too many issues with using LAB for aflatoxin binding for it to be safely promoted. Arguably, using binders in human food might even worsen food safety in the longer term. A more comprehensive food safety approach has to be taken to solve this ongoing crisis.
  • Zhang, Yuemei (Helsingin yliopisto, 2020)
    The thesis aimed to study the effects and mechanisms of freezing-thawing treatments on myofibrillar protein denaturation and to explore the role of myofibrillar protein denaturation in causing the formation of thaw loss. The freezing-thawing of porcine M. longissimus thoracis et lumborum (LTL) increased the free Ca2+ concentration and the subsequent chilled storage promoted an accelerated decrease of activities of calpain-1 and calpain-2, compared to unfrozen meat. Proteasome activity was observed to be around 40% lower after freezing-thawing. The observed increased purge loss and decreased water-holding capacity (WHC) of myofibrils indicated myofibrillar protein denaturation occurring during the freezing-thawing treatment. In the investigation of freezing-induced denaturation of myofibrillar and sarcoplasmic proteins of LTL in relation to freezing rate, fast frozen samples (cold metal plate/-80°C) had a characteristic freezing time of 12 min, while samples frozen at slow rate (air/-20°C) had a freezing time of around 174 min. Slow freezing led to around 30% larger thaw loss in parallel with reduced WHC and increased surface hydrophobicity of myofibrils, indicating more severe myofibrillar protein denaturation in slow compared to fast freezing. A model is proposed to explain the importance of myofibrillar protein denaturation in relation to the freezing rate in the origin of thaw loss: In slow freezing, protons are accumulated with concentrating solutes in the unfrozen water leading to a decline of pH causing denaturation of structural proteins. In fast freezing small ice crystals might trap protons inducing less decline of pH and thus less myofibrillar protein denaturation and reduced thaw loss when compared with slow freezing. Sarcoplasmic protein denaturation also was shown to occur in freezing-thawing as evaluated by differential scanning calorimetry and tryptophan fluorescence properties of drip, which was, however, independent of freezing rate. The role of decreased pH (from pH 5.5 to 5.2), combined with high ionic strength (2 M KCl), in causing myofibrillar protein denaturation was studied by exposing fresh minced meat to either high ionic strength only or to high ionic strength with decreased pH to mimic conditions estimated to be in the unfrozen water of frozen meat during freezing. Exposure to high ionic strength caused an increase of WHC of the isolated myofibrils, whereas exposure to high ionic strength combined with low pH reduced WHC and increased surface hydrophobicity of the myofibrils. These results suggest that decreased pH combined with increased ionic strength in the unfrozen water of frozen meat largely would explain myofibrillar protein denaturation and thus the thaw loss occurring in frozen-thawed meat. The storage at -3 °C of fast or slow frozen pork prior to final thawing at 2 °C diminished the impact of the freezing rate on myofibrillar protein attributes, and differences between fast and slow freezing were no longer significant for WHC and surface hydrophobicity of the isolated myofibrils when frozen samples subsequently were kept at -3 °C for 7 days. The results suggest that a marked myofibrillar protein denaturation is taking place with extended storage time at -3 °C. In conclusion, freezing-thawing increases water loss in meat and slow freezing causes a higher increase when compared to freezing at fast rate. Myofibrillar and sarcoplasmic protein denaturation occurs in freezing and thawing. The rate of freezing produces a significant effect in the myofibrillar fraction: A slow freezing will develop a more severe protein denaturation than a fast freezing. Consequently, the myofibrillar protein denaturation, related to the freezing rate, is proposed to contribute to the generation of thaw loss. However, a subsequent storage of frozen meat at -3 °C before final thawing seems to diminish the beneficial effects of fast freezing on myofibrillar protein characteristics, compared to slow freezing, due to an additional protein denaturation. Therefore, it is recommended that meat industry adjusts the thawing capacity to minimize the passage time in temperature of -3 °C in meat.
  • Rantala, Tapio (Helsingin yliopisto, 2020)
    This study analyzes the political legitimacy of forest and forest-related nature conservation policies in Finland. Legitimacy is defined here that the forest and nature conservation regimes and related political institutions are perceived as rightful among the people. The major contribution of this study is the comprehensive conceptual framework of legitimacy based on several theories, mainly from political science. The framework analyzes the objects of support, patterns of legitimacy, performance evaluations, and how these relate to one another. In this study, the objects of support refer to forest-related political institutions; these include regulations and public incentives, as well as decision-making processes, political programs, and administrative procedures. The framework is intended to be especially useful in the empirical analyses of pluralistic public political discussion and uses a methodology developed for this purpose. The study also analyses the social values of organized political actors. The empirical part of this study explores a data set from Finnish print media discourse, based on letters to editors in three newspapers and in one journal, along with comments given during the preparation of Finland's National Forest Programme 2010. Another empirical data set consists of qualitative semi-structured interviews and the writings of the organized interest groups. Many different groups of citizens were found to participate in public discussion on forests. Quite a large number of individuals shared the overall publicity, despite the fact that there were some very active writers. Nature conservation organizations, researchers, and politicians were well represented. However, the participation of governmental officials from both the forest and environmental sectors can be characterized as insufficient, considering their importance in the implementation of policies. The study of letters to editors found that groups of common social values served as patterns of legitimacy in the performance evaluations of forest policies. These include welfare and wellbeing derived from forests; values related to nature conservation; democratic values; distributive justice; good governance; core regime principles; and fair markets. Of all performance evaluations, 52% were negative while 26% were positive and 22 % were mixed. Domestic, EU-level, and international legality were commonly perceived as sources of the legitimacy of policies. Finland's good international standing and its role as a moral and economic forerunner were very common principles in the evaluations in both the forest and nature conservation policies, in all parts of data. The same idea was also found central in the national forest programs and strategies. The shared goal of the Finns seems to be that the nation would be best in the world both in forest and nature conservation policies. Keywords: forest policy, nature conservation policy, political legitimacy, democracy, justice, public discussion .
  • Joensuu, Johanna (2020)
    Ozone (O3) and nitrogen oxides (NOx: nitrogen monoxide NO and nitrogen dioxide NO2) are reactive gases with an important role in atmospheric chemistry. Terpenes are a reactive subgroup of BVOCs (biogenic volatile organic compounds) emitted by plants. Needle or leaf surfaces are the first point of contact between the atmosphere and a plant. Boreal forests represent a significant portion of the global land area available for atmosphere-biosphere interactions. The aim of the study was to develop methods for observing the exchange of NOx in field conditions and to explore the roles of terpenes on needle surfaces and nitrate fertilization on the fate of O3 and NOx in plant-soil-atmosphere interfaces. The methods included whole-canopy measurements, shoot-scale chamber measurements, needle sampling and laboratory analyses, utilizing both continuous observations and experimental setups. In the studied low-NOx environment, the shoot-level NOx fluxes were too small to be monitored accurately in field conditions with an automated dynamic chamber. In addition to interference, the signal to noise ratio was low, and a significant proportion of the observed fluxes were to/from chamber walls. No clear NOx fluxes from Scots pine foliage were detected, and there was no effect of nitrogen fertilization on the observed fluxes. It seems unlikely that a fertilization treatment could cause significant NOx emission from boreal pine forests. The fluxes reported in our earlier studies included compounds other than NOx. Shoot terpene emissions and needle wax extracts were both dominated by monoterpenes. There was variation in the terpene spectra of both emissions and wax extracts. The proportion of sesquiterpenes was higher in the epicuticular waxes than emissions, and the observed sesquiterpene compounds were for the most part different in the emissions and wax extracts. The role of direct transport through the cuticle from sites of terpene synthesis may be more important than has been assumed.
  • Alam, Syed Ariful (Helsingin yliopisto, 2020)
    This study focused on modification of rye bran to produce high fibre extruded cereal foods with a good texture and structure. Rye bran addition during extrusion is challenging due to high levels of insoluble dietary fibre, which leads to less expanded products and a hard texture. Bran modification by particle size reduction or fermentation significantly improved both the structural and textural properties of extrudates. Moreover, optimization of the processing parameters such as increasing the screw speed, lowering the water feed rate, as well as the use of in-barrel hydration regimens further improved the textural properties. The applicability of rye bran in extruded products could thus be improved by particle size reduction and fermentation. The extruded food structure and texture had a direct effect on the mastication and bolus formation process in the mouth. A hard and dense extrudate structure required more mastication effort than a crispy structure. Crispy and porous structures easily disintegrated in the mouth and produced smaller bolus particles than a hard and dense structure. A smaller particle size of the bolus was associated with increased starch hydrolysis. The bolus particle size was more effective than the matrix composition in altering the starch digestibility. Increased dietary fibre intake via appealing snack products could help reduce chronic diseases. Knowledge obtained in this thesis on cereal matrix formation and digestion and the effects of added dietary fibre on the structural and textural properties of extruded solid foams will help the food industry to develop healthy and appealing products. Understanding process-structure-digestibility relationships of high fibre extruded matrices is essential for designing health promoting foods.
  • Räty, Mari (Helsingin yliopisto, 2020)
    Grasslands occupy 45% of agricultural land in Finland, but in provinces characterised by grassland-based dairy production the proportion can be 67%. Phosphorus (P) loads from grasslands to inland waters have received relatively little research attention. In the Finnish climate, soils are subjected to frost in winter and snowfall comprises a considerable part of total annual precipitation. Surface runoff is generated by limited infiltration of snowmelt water into partially frozen soil in spring, which is a crucial period for dissolved nutrient and soil particle transport, especially in central and northern Finland. This thesis examined the role of perennial grass vegetation in P dynamics in the soil-plant-water continuum and quantified P losses from grasslands under boreal conditions. Potential contributions of perennial vegetation to P losses were estimated indirectly, by determining changes in nutrient content of aboveground vegetation. Susceptibility of overwintering perennial ley regrowth to deliver P was assessed in a simulated snowmelt-induced surface runoff study. These approaches were complemented with five-year monitoring of a small (3.2 km2) agricultural and forested catchment, representing grassland-based dairy production areas in east-central Finland. Amount and inter-annual variation in P losses and erosion rate were quantified. The results showed that grasslands can release substantial amounts of plant-derived P when exposed to frost, freezing and thawing. Elevated P concentrations and losses of up to 0.69 kg ha-1 were detected in simulated snowmelt-induced runoff outflow. Higher P concentrations were also occasionally measured in early spring runoff at small catchment scale. More frequent freezing/thawing will enhance plant-derived P release, especially under a reduced snow layer and lack of insulating cover. In five-year monitoring of an agricultural sub-catchment with short-terms leys, where some fields were under grassland and others under cereals, mean annual total P (TP) losses were 1.0 kg ha-1 (range 0.6−1.5 kg ha-1). The proportion of this TP load transported as dissolved reactive P (DRP) averaged 44% (range 32−56%) for the agricultural sub-catchment and 34% (28−38%) for the whole catchment area, reflecting low erosion rate under the protective grass cover. Five-year annual soil erosion rate from the agricultural sub-catchment was only 46−287 kg ha-1 (mean 115 kg ha-1 yr-1). The results also suggested that P losses were partly associated with loss of organic material. These results indicate a need for P monitoring based on chemical analysis of water samples, instead of on turbidity measurements. Grasslands are prone to DRP losses, but substantially less susceptible to erosion than arable fields during harvest years. In Finnish short-term ley rotations, grass leys are typically renovated every 3−4 years, often including autumn ploughing, which can increase erosion and particulate P losses. Thus when quantifying P loads to waters from short-term grass leys, erosion and nutrient losses within the whole ley cycle should be considered, including the ley establishment and renewal year. Keywords: phosphorus, erosion, grassland, ley rotation, nutrient loading, surface runoff, winter
  • Córdova, Raúl (Helsingin yliopisto, 2020)
    Smallholder farming is known to be highly vulnerable to climate change and climatic variability, especially in mountainous regions of the developing world, mainly due to high environmental exposure and sensitivity and low adaptive capacity to a variety of climate and non-climate stressors. Maintenance of more sustainable and resilient agricultural systems are essential for guaranteeing sustainable management of land and for securing the livelihoods of millions of rural and urban people. The aim of this study was to study the main socioeconomic and environmental parameters which influence the adaptation of smallholder farmers and their farming systems to climate change and climatic variability. The adaptation opportunities and constraints of smallholder farming systems were determined comparing their biophysical and socioeconomic sustainability (Study I) and their vulnerability to climate change and climatic variability (Study II and Study III). The data was collected by interviewing 60 households (30 agroforestry systems and 30 conventional systems) during 2015–2016. Semi-structured questionnaires were designed to collect primary biophysical, socioeconomic and sustainability data, while a modified Climate Change Questionnaire of the World Overview of Conservation Approaches and Technologies (WOCAT) was used to collect the vulnerability data. The characteristics of the farming system were analysed applying a comparative analysis approach. Qualitative variables were analysed through descriptive statistics (Crosstabs and Chi-square), while Independent Samples t test was applied for the quantitative variables. The main findings highlight the role of agroforestry systems in supporting the sustainability of the systems and farmers’ livelihoods: higher levels of agrobiodiversity, greater diversification of livelihoods, more secure land tenure, higher on-farm incomes, and greater diversification of irrigation sources. In addition, agroforesters and conventional farmers perceived climate change in the same way, as a continuing trend of rising temperatures and decreasing precipitation. Results also indicate that conventional systems had greater exposure to solar radiation, pests, weeds, disease outbreaks and droughts compared to agroforestry systems. By contrast, agroforestry systems presented greater potential to decrease exposure and sensitivity, and greater assets to support farmers’ adaptive capacity, especially in aspects related to social environment, and access to information and production infrastructure. Keywords: Andean smallholder agroforestry and conventional agricultural systems, socioeconomic and biophysical sustainability, exposure, sensitivity, adaptive capacity, traditional knowledge
  • Matkala, Laura (Helsingin yliopisto, 2020)
    The growing conditions in northern boreal forests have remained similar for millennia. However, amplified climate change may cause higher mean annual temperatures and precipitation sums, longer growing seasons, along with increased occurrence of extreme weather events (drought, heavy rain, or summertime frost) in the region. The relationship that forest vegetation has with soil nutrients and the exchange of carbon dioxide (CO2) between the forest and atmosphere may change. This dissertation focuses on quantifying the baseline status of northern boreal forests from these aspects, to be able to predict theupcoming changes more precisely. Soil total phosphorus (P) and nitrogen (N) contents were important factors in explaining the community composition of understory vegetation in the study site. The site was located in a region near a phosphate ore, where soil nutrient contents are highly variable. The number of herb, grass, and sedge species increased with N and P contents in the humus, especially with P. The increasing P content, on the other hand, positively correlated with downy birch (Betula pubescens Ehrh.), which was the dominant tree species of the research plot. The understory vegetation had an important role in the CO2 exchange rates of a northern boreal Scots pine (Pinus sylvestris L.) forest site. The annual CO2 dynamics varied between the canopy and understory, so that when the canopy began photosynthesizing in the spring, the understory was still under snow cover. The cumulative temperature sum had a higher positive correlation with photosynthesis than the total ecosystem respiration (TER) rate of the pine site. Overall, the pine site was a weak carbon sink during the growing season, although it temporarily turned into a carbon source during a cold and rainy summer. Extreme weather events, and their effects on the CO2 dynamics of forests, were studied on a Scots pine site and a Norway spruce (Picea abies (L.) Karst.) site. Both sites had experienced extreme summers during the studied times, but the CO2 flux rates in the Norway spruce site responded more clearly to them. The TER rates of the Norway spruce forest declined when it was warm and dry. This likely happened because of decreased decomposition of organic matter. The decline was, however, only temporary, and TER returned to normal when the temperature and precipitation returned to their average levels. Thus, the studied forest sites seemed to, so far, be rather resilient towards extreme weather events. Several studies have found that N availability will increase because of warmer temperatures, which speeds up decomposition and nutrient mineralization. However, decomposition may potentially slow down in some spruce forests due to heat. Local variation may thus be high when it comes to the availability of nutrients or to the CO2 dynamics of forests. While modeling studies are important for predicting the responses of northern forests to climate change on the large scale, our research reminds that local-scale studies are also inevitable for gaining a more precise picture.

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