Andmebaasi logo

3. Doktoritööd

Selle kollektsiooni püsiv URI


Viimati lisatud

Nüüd näidatakse 1 - 20 145
  • Kirje
    The estimation of stocked and natural European eel (Anguilla anguilla) populations in Estonian waters
    (Estonian University of Life Sciences, 2024) Bernotas, Priit; Vetemaa,Markus (advisor); Nõges, Peeter (advisor); Institute of Agricultural and Environmental Sciences; Ložys, Linas (opponent)
    Eels, due to their mysterious life cycle and appearance have long fascinated scientists and fishers alike. In Estonia, similarly to the rest of Europe, eel populations have faced dramatic changes over the last decades, giving researchers a tough task to find out the factors behind these changes. My thesis focused on different aspects regarding the fisheries and welfare of eel in Estonian coastal and freshwater habitats. We studied a long-time series of commercial landings, scientific surveys, restocking efforts, and environmental variables, to shed light on the dynamics of these mysterious creatures. One observation from our investigation is the decline in both commercial and recreational landings of eels along the Estonian coast since the 1970s where data was available. This trend is consistent with a broader pattern seen all across Europe. However, with the fall of the Soviet Union at the beginning of the 1990s there was a sudden growth in eel landings on the Estonian coast. This was most probably due to changes in fishing practices, improvement in registering the catches, and growth in fishing effort rather than the recovery of local eel stocks. Since 2008 the landings of small fyke nets in particular dropped sharply with the main reason aside from the declining eel population being reduced effort as well as the diminishing profitability of using such gear. As opposed to small fyke nets, the number of large fyke net licenses remained unchanged. As eels are not specially targeted by large fykes the changes in the eel landings also reflect the decline of eel biomass in the coastal areas. Restocking is a part of eel management strategies in many European countries, including Estonia. Initially aimed at preserving traditional eel fisheries, most notably in Lake Võrtsjärv, restocking programs have evolved in response to declining stocks and regulatory frameworks. Our research highlights the importance of optimizing restocking efforts, considering factors such as stocking density, water conditions, and prey availability. For example, eels released to waterbodies as glass eels, tend to fare better in lakes with lower stocking densities, mixed water column, and abundant benthic invertebrates. Inland water bodies vary in their suitability for eel restocking, with well-mixed, nutrient-rich lakes offering the most optimal conditions for growth. Environmental factors, such as the prevalence of cyanobacteria, can negatively impact restocked eel populations, highlighting the overall importance of ecosystem health concerning eel management. While there have been numerous studies on eel migration, the topic is complicated and often raises a lot of questions while providing not so many answers. Restocked eels show the ability to navigate from freshwater habitats to the sea, however, their journey can be far from straightforward. Some individuals have displayed a surprising behavior of returning to their rivers of origin, spending extended periods in freshwater before resuming their migration towards the ocean. While this behavior exposes them to additional risks from predators and fisheries, it once again confirms the complexity of eel migration strategies. By investigating the Estonian eel populations, our study affirms the need for holistic management approaches that consider the interconnectedness of ecosystems and human activities both locally and internationally. When we understand the processes that influence the dynamics of eel populations, we can work towards the recovery of these mystic and unique creatures.
  • Kirje
    Leaf structure-function relationships and responses to plant hormones in non-seed plants
    (Estonian University of Life Sciences, 2024) Wuyun, Tana; Niinemets, Ülo (advisor); Institute of Agricultural and Environmental Sciences; Rinnan, Riikka (opponent)
    Non-seed plants are prosperous on Earth, but until now there are many mysteries about them in plant science. In the current thesis, non-seed plants were studied under two conditions: non-stressed and stressed. When under optimum conditions, leaf structural, chemical, and photosynthetic traits of non-seed plant species were studied to reveal the life strategy they chose for living. Compared to the seed plants, these early land plants tend to adopt a more conservative strategy by investing more resources to build up a robust body structure, sacrificing their capabilities to photosynthesize. Leaf density is found to be a fundamental trait (instead of the classical structure trait leaf mass per unit area) that represents structural characteristic of a plant leaf; thus, it helps to uncover trade-offs in a spectrum of interrelationships between different plant functional traits. When under stress (simulated by applying phytohormones), certain defense pathways in non-seed plants are activated. In general, non-seed plants behave similarly to seed plants in terms of both gas exchange characteristics and volatile organic compound emissions. However, there are differences. First, only four fern species out of nine close their stomata upon abscisic acid, showing a species-specific characteristic in this plant lineage; second, upon methyl jasmonate, one of the spikemosses Selaginella martensii emits a should-be time-consuming volatile compound linalool in a faster manner compared to the seed plants. Moreover, this spikemoss utilizes an alternative signaling pathway rather than the classical jasmonate pathway in seed plants.
  • Kirje
    Modelling of large shallow lake food web based on long term monitoring data
    (Estonian University of Life Sciences, 2024) Bhele, Upendra; Cremona, Fabien; Institute of Agricultural and Environmental Sciences; Lobry, Jérémy (opponent)
    Climate change poses a serious threat to freshwater ecosystems. With population growth, the demand for food production increases, potentially leading to excessive use of natural resources, high nutrient loads, eutrophication, and overfishing in water bodies. Modelling the food web is a valuable solution for understanding the key processes and ecological issues in a lake ecosystem, as it avoids the need for expensive experimental studies. Ecological modelling allows the exploration of the interconnected effects of environmental conditions, nutrient loading causing eutrophication, and fishing activities on the aquatic ecosystem. The Ecopath model, along with its modules Ecosim and Ecospace (EwE), is a widely used tool for investigating the structure of aquatic food webs, encompassing both top-down and bottom-up control mechanisms from producers to predatory fish to detritivores. This doctoral thesis analyses the potential impacts of climate change and associated fluctuations in water levels on the biodiversity of Lake Võrtsjärv. The modelling process considers the biomasses of all major functional groups in the lake. Using the spatial module Ecospace within the EwE modeling suite, scenarios based on realistic water level fluctuations were examined. The models also simulated top-down and bottom-up processes based on predator-prey relationships and commercial fishing data. These models were employed to understand the process-based dynamics of phytoplankton, invertebrates, fish groups, and other key functional groups in the ecosystem. The outcome of the research shows that modelling indicated that zooplankton is not efficient in controlling the biomass of cyanobacteria, leading to detritus accumulation. Global warming and eutrophication are expected to increase cyanobacterial production and the frequency of algal blooms, especially in shallow lakes. Consequently, lakes may become more dependent on detrital organic matter in the near future. Reducing factors causing eutrophication would decrease cyanobacterial dominance, thereby improving the overall feeding capacity of zooplankton. Ecospace modelling to elucidate the effects of water level changes on functional group biomass and spatial distribution in the lake showed that prolonged water level decline could trigger a trophic shift, increasing the number of predatory groups at the expense of plankton and smaller fish. A stable water level would be more beneficial for Lake Võrtsjärv biodiversity than significant water level fluctuations. The third objective of this study was to investigate simulating biomass changes in several functional groups, whether trophic cascading was “bottom-up” or “top-down” in shallow lakes. The study simulated biomass changes in multiple functional groups. The "Keystoneness" analysis revealed that the macrozoobenthos as a lower consumer group and adult pikeperch as a top predator on the food web is equally important. Sensitivity analysis showed that changes in the biomass of phytoplankton, zooplankton, and macrozoobenthos affect the biomass of all major functional groups more than changes in the fish population. The models demonstrated that a sudden change in the food web (plankton, macroinvertebrates) due to eutrophication or climate change poses a threat to the entire functioning of the food web, as environmental tolerance limits have already been reached through maximum carrying capacity.
  • Kirje
    Evaluating ecosystem services and their impact on human well-being in the peri-urban landscape of Harku Municipality, Estonia
    (Estonian University of Life Sciences, 2024) Nevzati, Fiona; Külvik, Mart; Storie, Joanna Tamar; Institute of Agricultural and Environmental Sciences; Geneletti, Davide (pre-opponent); Ogletree, Scott (opponent)
    This doctoral thesis focused on the complex relationship between urbanisation and human well-being, specifically in peri-urban areas—the transitional zones between urban and rural settings. Through interdisciplinary research, it explored how these landscapes influence quality of life and provide essential ecosystem services in the Harku municipality, Estonia. The thesis underscored the significance of cultural ecosystem services (CES), encompassing the intangible benefits derived from nature. It employed innovative methods like landscape character assessment (LCA) and the CES framework to explore these concepts further. By analysing landscape patterns and anticipating future scenarios, the study provided insights for sustainable planning practices. Key findings revealed the essential role of forests in cognitive well-being, schoolyard gardens in spiritual enrichment, beaches in social cohesion, and the sea in stress relief. The study was informed by expert opinions and incorporated secondary data from a resident survey on the quality of life in the municipality. Furthermore, the thesis provided recommendations for fostering more sustainable spatial planning development in peri-urban areas, striving to strike a balance between environmental conservation and human well-being. The strategic integration of CES mapping into planning frameworks facilitates the identification of ecosystem services crucial for sustainable peri-urban development, prioritising both environmental preservation and societal welfare.
  • Kirje
    Transcriptomic and volatile organic compounds analysis of resistance mechanisms and diversity of late blight pathogen populations in the Baltic Sea region
    (Estonian University of Life Sciences, 2024) Agho, Collins Aimuaenvbosa; Niinemets, Ülo; Runno-Paurson, Eve; Kaurilind, Eve; Institute of Agricultural and Environmental Sciences; Abuley, Isaac Kwesi (opponent)
    This thesis addressed in part the dynamics and diversity of late blight pathogen populations in unstudied regions (Estonia islands and Pskov region of north-western Russia) by understanding changes in the spatiotemporal variation of the P. infestans population structure, the prevalent reproduction mode, genotypic and phenotypic diversity and the impact of transboundary migration and gene flow on the P. infestans population (Paper I and II). Mating type determination, metalaxyl response and SSR marker genotyping of P. infestans isolates were used in the first and second experiments. Our result suggests a predominance of sexual reproduction that may have resulted in the observed high genotypic diversity and a high proportion (> 60%) of unique genotypes in these unstudied regions. Time-dependent changes in metalaxyl response and rapid changes in the pathogen populations with the absence of shared genotypes over the years were observed. Overall, there was a lack of genetic differentiation and an absence of local adaptation allowing for the exchange of genetic materials among the P. infestans populations of the Estonian islands and mainland Pskov region P. infestans populations, and between Estonian island and mainland Pskov regions populations. Secondly, the diversity of the chemical profile (volatile organic emission/VOC) of potato cultivars with variation in late blight resistance background was examined (Paper III). The result indicates the presence of qualitative and quantitative differences among the potato cultivars, and the dominance of terpenoids in the emission blend. The composition of sesquiterpenes was cultivar-specific. Interestingly, the VOC emission blend accounted for a high proportion of variation among the cultivars, and the total terpenoid and total constitutive VOC emission scale positively with resistance. The use of VOCs holds promise as a fast innovative, non-invassive marker for the selection of resistant genotypes. Lastly, an improved understanding of the molecular mechanism underlining the high field resistance to late blight disease of a widely grown potato cultivar (Ando) in Estonia was achieved using RNA sequencing technology (Paper IV).
  • Kirje
    Sustainable approaches to oilseed rape pest control : steps towards to integrated pest management
    (Estonian University of Life Sciences, 2024) Vilumets, Silva; Veromann, Eve; Institute of Agricultural and Environmental Sciences; Beckmann, Michael (opponent)
    Intensive agricultural has diminished the natural and semi-natural habitats in the agricultural landscapes, negatively impacting biodiversity. To maintain a biologically diverse agricultural landscape supporting various species, diversity and heterogenity are crucial. Oilseed rape, one of the most important crops in agriculture, is an attractive food source for many arthropods. However, it faces challenges from several insect pests such as the pollen beetle and cabbage seedpod weevil. Synthetic insecticides are mainly used to control the pests but both pests have developed resistance. Therefore, finding effective environmentally friendly pest control methods is crucial. The study revealed that winter oilseed rape fields located over 500m from the previous year's field had significantly fewer pollen beetles and cabbage seedpod weevils compared to fields closer than 500m. Field-adjacent habitats had minimal impact on pest abundance, highlighting the significance of temporal and spatial separation of crop fields in mitigating pest populations. The study also explored parasitoid presence, revealing high parasitism rates in all years, even up to 90%, consistently exceeding the 32% threshold for effective natural pest control. Parasitism rates were not significantly affected by the distance from the previous year's oilseed rape fields but thrived in landscapes with diverse natural and semi-natural areas. Essential oils like Cinnamomum verum and Cuminum cyminum proved to be effective against the cabbage seedpod weevil. However, the results also showed their lethal effect on parasitoids, both adults and larvae. Moreover, monitoring for species that may benefit from the changing climate conditions, build up their populations and reach to pest status, is crucial. The study identified C. sulcicollis, previously uncommon in Estonia damaging oilseed rape plants. While not presently considered an important pest, climate-induced distribution changes may alter its status. This highlights the urgency of studying various species affecting oilseed rape, especially given the changing climate. The thesis provides an important information about the biology of both pests and their natural enemies, along with practical guidance for producers on crop rotation. It emphasizes the importance of a diverse landscape and finding alternative means of control to reduce the use of synthetic insecticides, aligning with the goals of the European Union agricultural strategy "Farm to Fork".
  • Kirje
    The effect of fertilizing and modified atmosphere storage on blueberry (Vaccinium spp) fruit quality
    (Estonian University of Life Sciences, 2023) Koort, Angela; Karp, Kadri; Starast, Marge; Moor, Ulvi; Institute of Agricultural and Environmental Sciences; Martinussen, Inger (opponent)
    There are few cultivated plants that grow well on acidic peat fields. However, blueberries (Vaccinium spp) are calcifuges that thrive in low pH and have lower Ca requirements compared to other temperate fruit crops. As a result, they are suitable for revegetating abandoned peatlands. The increase in production and consumption of organic food is one of the current trends, driven in part by consumers’ perception of organic food as being more sustainable and healthier than conventional. Since previous studies on blueberry cultivation in abandoned peatlands primarily focused on synthetic mineral fertilizers, it is important to study sustainable fertilizer strategies for organic blueberry cultivation. Revegetating abandoned peatlands with blueberries could also reduce the negative impacts of environmentally sensitive peatland areas. Blueberries are marketed as health promoting food, therefore maintaining fruit quality during postharvest storage is equally important to prolonging postharvest storage period. Extending the blueberry postharvest life through modified atmosphere storage and preserving their sensory and nutritional quality could be an option to add value to organically grown blueberries. However, there are very few postharvest studies concerning organically grown blueberries. The aims of the research were to find out the effect of: 1) different organic fertilizers on the plant growth, yield and biochemical parameters of fruits of half-highbush blueberry ‘Northblue’ under peatland conditions; 2) modified atmosphere packages on the external quality and the nutritional value of the fruits of organically grown lowbush blueberry and half–highbush blueberry ’Northblue’. Based on the results of fertilization experiments conducted on an abandoned peat field with half–highbush blueberry ‘Northblue’, the seaweed–based low nutrient fertilizer Biolan 4–1–2 could be recommended for organic production in peatland areas. It demonstrates more stable yield performance and has a lower impact on peat pH. Algomin fertilizer, which is based on marine algae Lithothamnium calcareum, increased the soil pH up to 5.2 and suppressed the plant growth during the juvenile growth stage. Organic fertilizers containing chicken manure resulted in comparable vegetative growth and yield as the plants receiving mineral fertilizer. The yearly variation in weather conditions was more important in determining fruit biochemical content than the type of fertilizer used. The application of seaweed–based organic fertilizer Biolan 4–1–2 resulted in similar total polyphenol content in fruits as observed in the mineral fertilizer treatment. The postharvest storage experiment with lowbush and half–highbush blueberry ‘Northblue’ demonstrated that the Xtend® modified atmosphere package prolonged the postharvest life of lowbush blueberries by 15 days and half-highbush blueberries by 9 days. The LDPE modified atmosphere package did not prolong the postharvest life of lowbush blueberries, but extended the postharvest life of ‘Northblue’ by 9 days. The CO2 content was significantly higher in Xtend® package compared to the LDPE at the end of the storage period. Both modified atmosphere packages had an effect on the taste–related properties of blueberries irrespectively of the taxa. By the end of the storage period, the SSC:TA ratio of the blueberries in the modified atmosphere decreased compared to both the initial value and the berries stored in a regular atmosphere. The content of anthocyanins significantly increased under all storage conditions, regardless of the taxa. The genetic differences were more important concerning fruit firmness, shrivelling, and decay. Both modified atmosphere packages had an impact on the firmness and the shrivelling, but the fruits of the half–highbush blueberry ‘Northblue’ were firmer and less shrivelled compared to the lowbush. Based on results, the Xtend® modified atmosphere package can be recommended for blueberry postharvest storage. However further studies are needed to find the metabolic differences of blueberry taxa and to match the respiration rates of the product with the permeation rates of the packages. Additionally, the use of biodegradable films should be considered in order to ensure sustainability.
  • Kirje
    Valorisation of fruits of rowan (Sorbus spp.) genotypes for functional food ingredients
    (Estonian University of Life Sciences, 2023) Sarv, Viive; Venskutonis, Petras Rimantas; Bhat, Rajeev; Rätsep, Reelika; Institute of Agricultural and Environmental Sciences; Heinonen, Marina (opponent)
    The lack of interest in rowanberries has been caused by the specific astringent taste, which doesn`t allow to use them as raw fruit for eating. At the same time, rowanberries have been used in traditional medicine as a good source of vitamin C, anti-inflammatory and as diuretic drug. Rowanberries have also been used to make juice, but the juice pressing residue hasn`t got a practical application. Detailed information on the composition and antioxidant properties of this promising natural source is important for the development of functional supplements from rowanberry pomace. Therefore, in this work, the antioxidant characteristics of the fruits, juice and pomace of 16 sweet rowanberry cultivars (cvs) and wild rowanberry were determined. Based on the above-mentioned characteristics, the pomace of cvs with good antioxidant potential and the highest polyphenol content were selected for further applied research. The selected materials were the pomaces of cvs 'Likernaja', 'Solnechnaja', 'Sahharnaja' and wild rowanberry. A mixture of 'Likernaja', 'Solnechnaja' and wild rowan pomaces was used to prepare functional ingredients for pork meatballs. The metabolomics of the meatballs on the day 14 of storage, revealed that aldehydes and ketones, which indicate the meat spoilage, were present only in the control sample, as well as the content of linoleic acid derivatives had decreased only in the control sample, which indicated the oxidation of unsaturated fatty acids. Thus, it could be concluded that it is possible to inhibit the oxidation of meat products with rowanberry pomace based ingredients.
  • Kirje
    Quantitative impacts of interactive biotic and abiotic stresses on plant performance: stress responses, priming, and acclimation
    (Estonian University of Life Sciences, 2023) Sulaiman, Hassan Yusuf; Niinemets, Ülo; Institute of Agricultural and Environmental Sciences; Staudt, Michael (opponent)
    Environmental stresses in plants result in emissions of volatile organic compounds (VOC) and reductions in photosynthesis. Plants experience multiple abiotic and biotic stresses sequentially or simultaneously and responses activated by one stress can alter responses activated by the other stress. The main aim of this thesis was to study the responses of plant physiological traits to interactive biotic and abiotic stresses depending on the severity of the different stresses, sequences, and duration in four model species. We used Achillea millefolium in the first experiment and O. vulgare in the second experiment to investigate the impact of moderate heat (35°C for 1 hr, heat priming) on foliage photosynthesis and VOC emissions responses through 72 h heat shock stress (45°C for 5 min) recovery period. Heat-primed plants demonstrated higher heat shock tolerance of photosynthetic activities, evident in smaller reductions in the rates of photosynthesis and faster recovery, and lower emissions of stress VOC indicating lower oxidative stress. In primed O. vulgare, a certain decrease in photosynthetic activity remained suggesting a sustained priming effect, and VOC emissions rose at later phases of recovery indicating the activation of biochemical defense in primed plants. In the third experiment, we studied how infestation with Trialeurodes vaporariorum alters photosynthesis and VOC emissions in O. vulgare through 48 h heat shock recovery period. In non-infested plants, photosynthesis did not recover, but in infested plants, photosynthesis recovered fully, indicating a greater heat stress tolerance. In infested plants, heat shock resulted in much lower stress VOC emissions that recovered to pre-stress levels at the end of the experiment. This suggests that insect phloem feeding decreased VOC emissions responses to heat shock and enhance the thermal acclimation of photosynthetic activities. In the fourth and fifth experiments, we quantified the impact of the biotrophic crown rust fungus, Puccinia coronata on foliage photosynthesis and VOC emissions with increasing the severity of infection in the primary host Avena sativa and the alternate host Rhamnus frangula. In A. sativa, decreases in photosynthesis were much greater and emissions of VOC were strongly enhanced with increased severity of infection, but the emissions decreased during severe infections due to an overall inhibition of physiological activity. In R. frangula, VOC emissions were elicited to a minor degree, but surprisingly, emissions of constitutive isoprene were strongly enhanced. These results suggest differential biochemical responses and varying fungal sensitivity in the two hosts. We argued that the greater infection sensitivity in A. sativa was due to fungal interaction with warm weather that might have enhanced the fungal virulence.
  • Kirje
    Novel approaches in multi-sensor unmanned aerial vehicles as basis for enhancing fire management frameworks
    (Estonian University of Life Sciences, 2023) Sampaio de Lima, Raul; Sepp, Kalev; Lang, Mait; Vain, Ants; Institute of Agricultural and Environmental Sciences; Remmel, Tarmo (opponent)
    Introduction. Climate changes are affecting the world, making wildfire understanding vital, and Estonia might experience an increase in the frequency of wildfires in the forthcoming years. Despite efforts to integrate fire management actions and research, many findings remain in "grey literature." This gap calls for formal research to evaluate the efficacy of these strategies. Recently, Estonian initiatives seek to foster collaboration between research and government entities. This thesis thus aims to contribute to the topic by developing knowledge on remote sensing, particularly UAV-based approaches, to improve fire management frameworks. Methods. The study involved various Estonian locations. Paper I examined how UAV flight parameters affect data quality in Lahemaa National Park. Papers II and IV estimated aboveground biomass using multispectral imagery and hyperspectral data from the Agricultural Research Centre in Kuusiku, employing diverse machine learning methods and approaches. Paper III predicted soil moisture in Lavassaare Natural Reserve using optical UAV data and partial least squares regression. Lastly, Paper V maps Rosa rugosa occurrence across Estonian coast using UAVs, integrating these findings into a satellite dataset. Results and Conclusions. The study unveiled an optimal UAV collection strategy for Estonian forests, ensuring canopy and forest floor reconstruction. Machine learning and AutoML frameworks proved effective in estimating biomass, paving the way for automated algorithms. Developing distinct models or conducting field surveys at various periods emerged as the most effective approach for accurate soil moisture modelling. Lastly, a UAV-based methods aided post-fire monitoring and species mapping, allowing assessments beyond surveyed areas. Thus, the importance of these datasets shifted across management stages. Multispectral data aided pre-fire soil moisture estimation, while post-fire used photogrammetry for exposed areas. Integrating diverse remote sensing data improved modelling results, overcoming transferability challenges. Complementary use of RS and field data enhanced modelling, particularly in complex environments. Findings underlined potential in merging remote sensing data for precise variable modelling, enhancing accuracy and agreement toward improved fire management systems.
  • Kirje
    Биология и агротехника лечебных и лечебнокормовых культур в частности родиола розовая Rhodiola rosea L., рапонтика сафлоровидного Rhaponticum carthamoides (Willd) Iljin, анзура Allium suvorovii Regl. x Allium giganteum Regl. на минеральных почвах Эстоний [i.e. Эстонии]
    (2000) Heintalu, Aleksander
    Antud töö on dissertatsioon teaduste doktori (doctor emeritus) kraadi taotlemiseks ja kajastab kokkuvõtlikult katsete tulemusi, mis on tehtud ajavahemikul aastatel 1969(74)-1993. Katsed kestavad edasi. Katsed ja uuringud läbisid: Roosilõhnaline radioola / (Rhodiola rosea L.); Muguljumikas (Altaist) / (Rhaponticum carthamoides (Willd) Iljin); Lauk Ansuur Kesk-Aasiast / (Allium suvorovii Regl. x Allium giganteum Regl.); (lisaks Zen-Zen katsetes 1971-78). Katsete ülesandeks oli introdutseerida ja kultuuristada Eesti tingimustes kasvatatavaid haruldasi ja harvaesinevaid ravimtaimi, mis nende looduslikus areaalis on tänapäevaks praktiIiselt hävitatud. Selleks on töötatud välja optimaalne agrotehnika Põhja-Euroopa, eelkõige Eesti mullastiku tingimustes, millest võivad kasu saada ka teiste maade rahvad, kelledel on samaväärsed mullad. Kuni 1994 aastani polnud neid taimi peale muguljumika maailmas kultuuridena kasvatatud. Tööde-katsete käigus on uuritud antud taimede bioloogiat, väljatöötatud agrotehnika ning loodud nende taimede genofond edaspidiseks kiireks paljundamiseks ning kasvatamiseks. Kusjuures on selektsiooni ja ristamiste kaudu aretatud nende taimede uued kloonid ja paljundatud kloonimisega, mille seemned annavad juba 96-98% identseid, uusi kultuuristatud taimi. Kõik taimed läbisid: 1. Biomorfoloogilised uuringud 20-25 aastat. 2. Paljundatud taimematerjalile töötati välja agrotehnika, nii seemnetega kui ka vegetatiivselt. 3. Töötati välja rodioola, ansuuri ja teiste kultuuride (kummel, maasikas jm) kasvatus biotsönoosis, sest monokultuurina läheks nende kasvatamine väga kalliks. Taime preparaate katsetati ka loomade, lindude ja kalade peal: näiteks loomade vastupanu leukoosi haigestumisel suurenes 30-40% (nad ei haigestunud). Lindudel suurenes adaptsioon radioola kasutamisel 5-7% ja ansuuri kasutamisel 8-11%. Vikerforelli kasvatamisel suurenes kaladel eluskaal esimesel eluaastal 1,7 korda võrreldes kontroll grupiga. Inimestega tehtud katsetel täheldati, et rodioola preparaadi tarbimisel kannatavad nad rohkem radiatsiooni ilma letaalse lõputa, seejuures väheneb järsult metastaaside kasvukiirus pahaloomuliste kasvajate juures, (sellest ka antud katsete salastatus endises NSVL-is, neil oli strateegiline tähtsus). Kuna need taimed on tugevad immuunsuse tõstjad, saab neid kasutada ka immuunsusdefitsiitsete haiguste korral. Muguljumikat kasutatakse põrsaste, pullide (sugupullide), lindude, karusloomade, sugutäkkude jne. sugulise võimekuse tõstmisel. Katsed näitavad, et ka inimeste frigiidsuse ja impotentsuse puhul, mis on seotud sperma ja munarakkude elulisuse vähenemisega omab ta tervendavat mõju - suurendab järsult spermatosoidide arvu ja teeb elujõulisteks põletikulistest munasarjadest tulevad munarakud. Antud taimed vähendavad loomadel ahtrust esimesel laktatsiooniperioodil 15…17 pluss/miinus 0,83 % ja teisel ning kolmandal - 4-7 %. Selle töö (raamatu) abil on võimalik antud kultuuride igakülgne kasvatamine Eesti erinevais mullastikes ning mujal sarnastes tingimustes. Töö on kokkupandud mitte kultuuride lõikes, vaid agrotehnika järgi, et hoida ära iga kultuuri juures eraldi agrotehniliste katsete üksikasjalikku kordamist. A. Heintalu
  • Kirje
    Impact of cropping systems on soil microbiome and barley transcriptome
    (Estonian University of Life Sciences, 2023) Esmaeilzadeh Salestani, Keyvan; Loit, Evelin; Institute of Agricultural and Environmental Sciences; Singh, Jaswinder (opponent)
    Crop production needs to be more sustainable. Farmers are confronted with the challenge to use less nutrients while maintaining food security and other ecosystem services. Therefore, it is essential to examine the agricultural strategies that address sustainability. This dissertation compared the effects of conventional and organic cropping systems on soil biodiversity and gene expression patterns of barley in a five-field crop rotation. Soil DNA analysis showed that all treatments in organic cropping system as well as conventional treatments with low to medium rates of mineral fertilizers increased the diversity and changed the relative abundance of the soil microbiome. Conventional treatment with no added nutrients decreased bacterial and fungal diversity. Yield is important for food security, and thus it is important to understand the processes in the barley plant. The number of differentially expressed genes was higher in conventional treatments, particularly in N2 that received 80 kg of mineral nitrogen per hectare and provided the highest yield, compared to organic treatments. Amide and peptide metabolism and response to acid chemical and inorganic substances were enriched biological processes in studied conventional treatments whereas polysaccharide and glucan metabolic processes were among the dominant biological processes under organic treatments. Expression of ammonium transporters was analysed more precicely over the early stages of crop growth. Up-regulation of HvAMT1;1 started at the anthesis growth stage in the conventional system and its activity had a strong correlation with the nitrogen content of leaves and 1000-kernel weight. Knowledge about the mechanisms being impacted by different nitrogen rates and cropping systems are valuable for agronomists and crop breeders in increasing the sustainability in crop production.
  • Kirje
    Bio-waste composting in the framework of a circular economy
    (Estonian University of Life Sciences, 2023) Lanno, Marge; Shanskiy, Merrit; Kriipsalu, Mait; Kisand, Anu; Institute of Agricultural and Environmental Sciences; Fuchs, Jacques Gabrie (opponent)
    Organic wastes can be stabilized by composting and turned into solid organic fertilizers and soil improvers, while closing the cycle of nutrients. Evaluation of total nutrient concentrations, as well as safety and hygiene parameters of composts, are regulated; however, some beneficial properties of compost are not reported. The aim of this PhD thesis was to determine the value of fish by-catch, an underutilized type of biowaste, through proximity composting, and increase our knowledge about the properties and added value of various composts. The distribution of phosphorus forms and concentration and properties of humic substances were determined from the fish waste composts and compared with other common types of compost. This study confirmed that proximity composting of fish waste is technologically feasible and meets hygiene requirements according to regulations (temperature 1 h > 70 °C). Composts made from different input materials varied in relative proportions and concentrations of phosphorus forms. Fish waste compost contained the highest concentration of immediately bioavailable phosphorus (6.90–7.75 g P/kg DW; 57–66% of total phosphorus). All selected composts contained humic substances, including humic acids (HA) and fulvic acids (FA), but their concentrations, properties, and relative proportions depended on compost input materials. The HA/FA ratio, reflecting humification, was highest in horse manure compost (7.88) and lowest in chicken waste compost (1.42). Composts revealed similar peaks of excitation/emission matrices of fluorescence spectra for FA, but varied in their HA spectra. In conclusion, this PhD thesis highlights the potential value of small biowaste streams, which have not been sufficiently considered to date. Such waste can be a valuable source material for high-quality composts that can be used to improve the physical and chemical properties of soil, as well as to increase crop yields.
  • Kirje
    The impact of environmental disturbances on the gastrointestinal bacterial community and the viability of aquatic gastropods
    (Estonian University of Life Sciences, 2022) Kivistik, Carmen; Herlemann, Daniel Philipp Ralf; Käiro, Kairi; Tammert, Helen; Institute of Agricultural and Environmental Sciences; Beier, Sara (opponent)
    The freshwater salinization caused by global climate change and anthropogenic activities has received increasing attention in recent decades. Coastal freshwater areas and inland water bodies are affected by agriculture, road salt usage, urbanization and resource extraction, which increase the concentration of dissolved ions in freshwaters. Water salinity is an important factor distributing species along the salinity gradient according to their evolutionary adaptation. As a result of freshwater salinization, the habitats and the species composition are changing. The organisms' resistance to environmental changes can be facilitated by symbiosis with microorganisms. The gut bacterial community supports the digestion, plays a role in the immune control, reproduction and development, and increases the hosts' resistance to environmental disturbances. In this thesis, the impact of increased water salinity and antibiotic concentration solely and in combination with food source change on the gut bacterial community of freshwater organisms was examined. In parallel, the energy reserves of the host were measured, for estimating how organism copes with the stressful occurrences. It was found that the rise in water salinity can affect the gut microbiome, if the salinity increase exceeds the tolerable threshold (salinity ~3). Therefore, the disturbance intensity has the strongest impact on the gut microbiome. Salinity increase to 3 combined with an easily digestible, carbohydrate-rich food source resulted in the highest host's energy level. However, this combination had the strongest effect on gut bacterial diversity, by increasing the abundance of generalists and reducing overall bacterial richness. In order to find out from which source the gut colonizing bacteria come from, the water bacterioplankton and the biofilm (food source) bacterial community were examined. It turned out that the influence of water bacterioplankton was minimal, and the gut microbiome was more similar to food source, which is likely the main source of bacteria colonizing the digestive tract. The results of this work suggest that aquatic invertebrates and their gut microbiome can successfully tolerate mild salinization, even with changes in the food source.
  • Kirje
    Combining unmanned aerial vehicles and a mesocosm experiment to unveil plant communities shifts under global change conditions in coastal meadows
    (Estonian University of Life Sciences, 2022) Fernandes Bergamo, Thaisa; Sepp, Kalev; Ward, Raymond D.; Joyce, Christopher B.; Institute of Agricultural and Environmental Sciences; Edwards, Keith (opponent)
    Semi-natural grasslands are an essential part of the cultural landscape of Europe. Semi-natural grasslands are commonly characterised by a very high biodiversity, including rare species. Beyond the high biodiversity value, semi-natural grasslands worldwide provide many ecosystem services, including: carbon sequestration and storage, nutrient cycling, regulation of soil quality, habitats for migrating birds, erosion control, and flood regulation. Within the realm of semi-natural grasslands, coastal meadows are particularly important. However, coastal grasslands are threatened by a range of factors such as coastal squeeze, transformation into monoculture ponds, pollution, and climate change. Coastal areas are threatened at a range of spatial scales as a result of sea-level rise, and can include higher flooding frequency in coastal areas, salt water intrusion in aquifers, and potential declines in the extent of coastal wetlands. A warmer climate also implies a modification in precipitation patterns affecting runoff into the sea. In coastal areas, both water levels and salinity have a strong impact on species distribution and therefore on the structure and composition of aquatic and coastal floral and faunal communities. Consequently, plant communities in coastal meadows are expected to undergo changes in their composition and structure. The current thesis explores different methodologies to assess plant community distribution, above-ground biomass, and the effects of management type, duration, and intensity on sward structure using UAV-derived multispectral data and aerial photogrammetry. In addition, the keystone of this thesis is a mesocosm experiment that was used to assess shifts in species richness and abundance in plant community types in Estonian coastal meadows related to future change scenarios of water level and salinity for the Baltic Sea. a. Unmanned Aerial Vehicle (UAV) The use of UAV demonstrated to be able to identify plant community extent and distribution in high biodiversity value coastal meadows in West Estonia. Species diversity and biomass significantly influence the quality of data and this should be accounted for when planning the sample collection to achieve better results. This study has shown that UAVs are useful tools of mapping grasslands at a plant community level. Also, UAV showed to be possible to reveal the structure of the grassland and how it is affected by the management history. For example, the grassland turns more homogeneous under long-term monospecific grazing, b. Mesoscosm Experiment The mesocosm experiment in the present study revealed different temporal changes of wetland communities to altered salinity and water conditions, highlighting the response of plant species to environmental variables. These changes were not significant according to alteration of water level and salinity in the Open Pioneer community, but they were over time. On the other hand, Lower Shore and Upper Shore had significant changes according to time and treatments. These could be explained by dynamic differences in the communities, since Open Pioneer was more variable. c. Conclusions Both methodologies, remote sensing and the mesocosm experiment, are evidently important to evaluate the structure and function of Estonian coastal meadows. The mapping of the extent and structure of coastal plant communities allows an evaluation of the current state of the ecosystem. The mesocosm experiment helps to understand changes in plant community composition under altered conditions of water level and salinity in Estonian coastal meadows and consequently, understand how species richness, abundance, and biomass will respond to those changes. This information is important when considering the protection and potential management of these areas taking into account the species diversity of fauna and flora as well as that of livestock.
  • Kirje
    Alternative biocontrol strategies in the potato phytophthora infestans pathosystem for integrated management of late blight
    (Estonian University of Life Sciences, 2022) Najdabbasi, Neda; Mänd, Marika; Haesaert, Geert; Audenaert, Kris; Institute of Agricultural and Environmental Sciences; Larena, Inmaculada (opponent)
    Potato late blight caused by a fungus-like microorganism, Phytophthora infestans, has historically been one of the most tragic and devastating potato diseases, that can infect all aboveground and underground organs of potato. In the absence of control measures, the pathogen can cause extensive production losses during the cropping season. P. infestans can destroy the entire crop within 7-10 days under favorable conditions (periods of high moisture and moderate temperature), when disease incidence is high and plants are unprotected. P. infestans is known as re-emerging pathogen leading to the very serious damage to potato cultivation by increasing its aggressiveness towards the host, reducing fungicide efficacy, facilitating its survival in soil or plant debris. Concerning late blight management, despite increasing the frequency of chemical applications along with using resistant cultivars and healthy seed tubers, control of primary inoculum sources remains a major challenge in potato farming. Besides, there is a necessity to develop alternative methods that are less dependent on synthetic fungicides. Although breeding of resistant varieties is the top priority in agricultural systems, development of biological control practices has strongly been proposed as a promising alternative and sustainable strategy to manage late blight, with the aim of minimizing dependency on synthetic fungicides. To this aim, the present dissertation addressed a multilevel investigation of alternative biocontrol strategies in the potato-P. infestans pathosystem for integrated management of late blight (I, II, II). In this respect, different bioassays were performed during the course of PhD study with the main focuse on application of bioprotection strategies. (I) Biocidal activity of plant-derived compounds against Phytophthora infestans: an alternative approach to late blight management. In the first part of the study, biocidal activity of different essential oils (EOs) including juniper (Juniperus communis); clove (Syzygium aromaticum); thyme (Thymus vulgaris); cinnamon (Cinnamomum cassia); turmeric (Curcuma longa); tea tree (Melaleuca alternifoliai); pepper (Piper nigrum); rosemary (Rosmarinus officinalis); and a reference plant extract, Timbor® from Thymus vulgaris against the most aggressive genotype of P. infestans (EU-13-A2) were determined at different application rates. The main objectives of this study were: i) to evaluate effects of different concentrations of EOs and reference products on sporangial germination of P. infestans using optical density method (ii); to analyze effects of different concentrations of plant compounds on the pathogen mycelial growth; (iii) to examine the efficacy of different plant-derived compounds towards disease development in vivo; and (iv) to confirm the efficacy of the most efficient EOs for controlling late blight in greenhouse. Among nine tested compounds, thyme and tea tree EOs showed the strongest inhibitory effect on sporangial germination compared to the fungicide control Ranman-top®. Clove and thyme EOs as well as Timbor® significantly inhibited P. infestans mycelial growth even at the lowest concentration. Our outcomes supported the hypothesis that “Different concentrations of plant-derived compounds are effective to suppress sporangial germination and mycelial growth of P. infestans genotype (EU-13-A2)”. Additionally, some compounds were effective to control late blight on potato leaves in vivo and also under greenhouse conditions, where pepper, rosemary, thyme EOs and Timbor® showed reduction in disease development for over a month, supporting two other hypotheses as “Different concentrations of plant-derived compounds are effective to control late blight on potato leaves in vivo” and “Some selected concentrations of plant-derived compounds are effective to control late blight on potato plants in greenhouse”. The present study provided evidence for the potential use of commercial essential oils and/or plant extracts as botanical fungicides that can be an alternative to synthetic fungicides for controlling late blight disease, as they have low toxicity and residues, and of course are eco-friendly. (II) Green leaf volatile confers management of late blight: a green vaccination in potato There is increasing attention on the agronomic potential of volatile organic compounds (VOCs), as a natural and eco-friendly solution to protect plants from pathogens and environmental stresses. Green leaf valotiles (GLVs), as one of the major VOCs, prime mechanisms of plant’s defense for a stronger, faster, and earlier response upon further stress incidence, resulting in induced resistance to the upcoming stresses. Despite the unique capability of GLVs to inhibit a wide range of fungal pathogens, their functions as defensive compounds to control potato late blight, caused by the Oomycete pathogen P. infestans, has not been well studied. Therefore, the second part of the study addressed the potential role of the GLV Z-3-hexenyl acetate (Z-3-HAC) in decreasing the severity of late blight and underlying gene-based evidence leading to this effect. Hence, the objectives of this study were: (i) to investigate the protective potential of potato plants pre-exposed to the Z-3-HAC against five genotypes of P. infestans (EU-1-A1, EU-6-A1, EU-13-A2, EU-36-A2 and EU-37-A2) in vivo; and (ii) to examine the possible defense responses of potato plants pre-exposed to the Z-3-HAC against subsequent infection using molecular assays. To these aims, very susceptible potato plants (cv. Bintje) were firstly exposed to the Z-3-HAC using a push–pull cuvette system, before they were inoculated with the pathogen at different time points. We observed strong inhibitory effect on P. infestans genotypes in planta, resulting in a lower sporulation intensity, and disease severity (up to 70 %) compared to untreated plants, supporting the hypothesis that “pre-exposure of potato plants to the GLV Z-3-HAC has protective impact against subsequent infection with genotypes of P. infestans”. To verify the second hypothesis on “pre-exposure of potato plants to the GLV Z-3-HAC induces expression of defense-related genes’ against Phytophthora infection”, we used gene-specific primers involved in reactive oxygen species (ROS) and SA and JA synthesizes. It was shown that the transcript levels of several defense-related genes, especially those that are engaged in ROS production pathways were significantly expressed in potato plants. The present research provided insight into the role of Z-3-HAC in the increased protection of potato plants against late blight through plant immunity and offered new opportunities for the sustainable control of potato diseases. However, widespread use of GLVs in management practices remains a challenge, largely associated with high-cost procedures. (III) Combination of potassium phosphite and reduced doses of fungicides encourages protection against Phytophthora infestans In order to reduce the fungicide doses and spray programs, an integrated approach combining alternative methods of disease control with fungicides can be an encouraging way to meet long term consumer demands. Therefore, the last part of the study demonstrated a protective effect of the potassium phosphite (KPhi) compound against late blight when applied on different potato cultivars with different levels of resistance, resulted in the highest DSI reduction on the cultivar Bintje amongst all cultivars. In the second part of study, the control of P. infestans infection by KPhi compound combined with recommended and reduced doses of five different active ingredients (AIs) of fungicides including cyazofamid, mancozeb, mandipropamid, azoxystrobin, benthiavalicarb-isopropyl was evaluated on potato plants. The results from in vivo, greenhouse, and field experiments strongly revealed that synergy between phosphite and fungicide active ingredients could play an important protective role against Phytophthora infection, even for susceptible cultivars. Accordingly, three hypotheses successfully supported our study: “Detached leaflet bioassay allows rapid in vivo screening of KPhi efficacy, alone and in combination with different doses of active ingredients, against P. infestans on potato leaves”, “KPhi in combination with recommended and reduced doses of different active ingredients reveals the potential protective effect toward potato pathogen P. infestans in greenhouse”, and “Combination of KPhi with the most widely used fungicide shows the potential benefit of integrated control strategy against foliar blight development under multivariable field conditions”. This study suggested that optimizing formulations with the addition of KPhi would result in a reduction of active compounds of fungicides in potato farming. Additionally, the impact of KPhi on late blight development could make KPhi a potential component for incorporation into an integrated management system.
  • Kirje
    Ornamental plant growth and development depending on soil conditions modified by organic additives
    (Estonian University of Life Sciences, 2022) Escuer, Olesja; Karp, Kadri; Shanskiy, Merrit; Institute of Agricultural and Environmental Sciences; Tammeorg, Priit (opponent)
    Modern plant production results in an intense use of natural resources and chemical inputs, with consequences on the environment. Peat is widely used for ornamental plant propagation and growth in container soilless media, representing 90% of peat-based substrates produced in Europe. Peat production diminishes natural diversity and disrupts the water regime of mined areas. Peatlands, left without vegetation after peat excavation, turn from carbon sinks to sources of greenhouse gas emissions due to higher mineralisation rate. Therefore, it is necessary to find alternative materials for ornamental plant growth. The aim of this PhD thesis is to contribute to the improvement of sustainable horticultural practices and enhance the ornamental value of bedding plants. This thesis studies the reduction of peat use in container growing media and in mulching of landscape areas, by substitution with inorganic and organic materials obtained from organic wastes recycling. In the pre-cultivation stage of ornamental plants, it is possible to substitute peat with values above 50% of the tested hardwood biochar with an additional simultaneous liming effect in container growing medium. Furthermore, in landscape areas, the application of peat as a mulching material can be avoided, by replacement with alternative organic materials such as fresh grass clippings, pine bark, and cocoa bean shell, with an increase of plant ornamental value.
  • Kirje
    Effects of cropping systems on soil fertility and winter wheat dough quality
    (Estonian University of Life Sciences, 2022) Keres, Indrek; Tosens, Tiina; Niinemets, Ülo; Loit, Evelin; Institute of Agricultural and Environmental Sciences; Grausgruber, Heinrich (opponent)
    The long - term effect of organic and mineral nitrogen fertilizers on soil fertility in five - field crop rotation and on the quality of winter wheat grain yield and dough was studied in the doctoral thesis. The aim was to find out the long-term effect of organic and conventional cropping on total yield, soil fertility (phosphorus and potassium content, pH) and the combined effect of different cropping systems and year on the size distribution of starch granules, the yield of whole grain and fine flour, the interaction of gluten-starch on the rheological properties of wheat dough. The total yield of the five-field crop rotation was on average 25% higher than in organic farming due to mineral fertilizers. During the 10-year experimental period, the soil P content of the conventional treatments did not change, while the K content decreased to 40 mg K per kg dry soil and the soil became more acidic. The use of winter crops and well-composted cattle manure did not maintain the basic levels of P and K in the soil, which is why it is important to monitor the nutrient balance, especially in organic farming, so that soil fertility does not decrease. The effect of the cropping system on the size of the starch grains was not significant, but it was affected by the weather conditions during the experimental years. Flour yield was affected by the size distribution of starch granules, while the increased proportion of smaller diameter granules significantly increased the yield of fine flour. The quality of the dough was affected by several factors, with the nitrogen fertilization regime having a significant effect. If the protein content is more than 13% and the glutenin-gliadin ratio is optimal, the dough has a longer stability time, a lower softening degree and a higher dough quality. The quality of the dough varied more in the organic treatments. The amount of 150 kg/ha of mineral N applied in two parts before flowering ensured stable plant growth and protein and gluten content in different years. Treatments fertilized with lower amounts of nitrogen and organic treatments were more vulnerable to changing weather conditions.
  • Kirje
    Unmanned aircraft systems and image analysis in yield estimation and agricultural management
    (Estonian University of Life Sciences, 2022) Li, Kai-Yun; Sepp, Kalev; Vain, Ants; Burnside, Niall; Institute of Agricultural and Environmental Sciences; Tsai, Hui-Ping (opponent)
    This thesis aims to examine how machine learning (ML) technologies have aided significant advancements in image analysis in the area of precision agriculture. These multimodal computing technologies extend the use of machine learning to a broader spectrum of data collecting and selection for the advancement of agricultural practices (Nawar et al., 2017) These techniques will assist complicated cropping systems with more informed decisions with less human intervention, and provide a scalable framework for incorporating expert knowledge of the PA system. (Chlingaryan et al., 2018). Complexity, on the other hand, can be seen as a disadvantage in crop trials, as machine learning models require training/testing databases, limited areas with insignificant sampling sizes, time and space-specificity, and environmental factor interventions, all of which complicate parameter selection and make using a single empirical model for an entire region impractical. During the early stages of writing this thesis, we used a relatively traditional machine learning method to address the regression problem of crop yield and biomass prediction [(i.e., random forest regression (RFR), support vector regression (SVR), and artificial neural network (ANN)] to predicted dry matter (DM) yields of red clover. It obtained favourable results, however, the choosing of hyperparameters, the lengthy algorithms selection process, data cleaning, and redundant collinearity issues significantly limited the way of the machine learning application. We will further discuss the recent trend of automated machine learning (AutoML) that has been driving further significant technological innovation in the application of artificial intelligence from its automated algorithm selection and hyperparameter optimization of the deployable pipeline model for unravelling substance problems. However, a present knowledge gap exists in the integration of machine learning (ML) technology with unmanned aerial systems (UAS) and hyperspectral-based imaging data categorization and regression applications. In this thesis, we explored a state-of-the-art (SOTA) and entirely open-source AutoML framework, Auto-sklearn, which was built on one of the most frequently used machine learning systems, Scikit-learn. It was integrated with two unique AutoML visualization tools to examine the recognition and acceptance of multispectral vegetation indices (VI) data collected from UAS and hyperspectral narrow-band VIs across a varied spectrum of agricultural management practices (AMP). These procedures incorporate soil tillage method (STM), cultivation method (CM), and manure application (MA), and are classified as four-crop combination fields (i.e., red clover-grass mixture, spring wheat, pea-oat mixture, and spring barley). Additionally, they have not been thoroughly evaluated and lack characteristics that are accessible in agriculture remote sensing applications. This thesis further explores the existing gaps in the knowledge base for several critical crop categories and cultivation management methods referring to biomass and yield analysis, as well as to gain a better understanding of the potential for remotely sensed solutions to field-based and multifunctional platforms to meet precision agriculture demands. To overcome these knowledge gaps, this research introduces a rapid, non-destructive, and low-cost framework for field-based biomass and grain yield modelling, as well as the identification of agricultural management practices. The results may aid agronomists and farmers in establishing more accurate agricultural methods and in monitoring environmental conditions more effectively.
  • Kirje
    Small mammals and the lesser spotted eagle in ecotones : a case study on predator-preyhabitat relationships in agricultural landscape
    (Estonian University of Life Sciences, 2022) Tõnisalu, Grete; Väli, Ülo; Institute of Agricultural and Environmental Sciences; Laaksonen, Toni (opponent); Remm, Jaanus (pre-opponent)
    Nowadays, agriculture and other land uses have a crucial role in protecting different habitats and biodiversity. Forest/farmland edges are one source of biodiversity in agricultural landscapes. Trophic relationships have an essential position in species’ ecology. Predator-prey relationships is a well-studied model system providing ample information on ecosystem functioning. It is less common to analyse trophic interactions in the context of landscape composition, whereas preservation of biodiversity and species conservation should be associated with habitat conservation and, therefore, maintenance of ecosystem functioning. In this study, spatial and temporal landscape-prey-predator relationships were explored in a model system composed of the generalist avian predator and its various prey animals in non-intensively managed farmland. The aims of the thesis were to find out predator-prey-habitat relationships in agricultural landscapes between small mammals and the lesser spotted eagle and to give practical suggestion for agricultural land use to maintain biodiversity with agriculture. The species richness and abundance of small mammals were higher in ecotones and grasslands than elsewhere in the agricultural landscape. The positive edge effect was the strongest next to grasslands. The lesser spotted eagle preferred to forage near ecotones and, hence, in complex agricultural landscapes. Lesser spotted eagles preferred to hunt close to patch edges but avoided roads. A larger area of open habitats increased the abundance of small mammals in the landscape and diet of the lesser spotted eagle. Higher landscape diversity was reflected in a more diverse diet, i.e. higher proportions of alternative prey in the diet. It is essential to continue studying landscape-prey-predator relationships to get more detailed area-specific information and to be able to give practical suggestion for agricultural land use to maintain biodiversity with agriculture.