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This dissertation contributes to research on generating actionable knowledge for coastal governance to enhance the resilience of coastal social-ecological systems (SES) to climate change. It does this by providing theoretical, methodological and empirical insights on three research questions (RQs). These are: (1) what is a more actionable concept for applying the concept of resilience in coastal governance?; (2) what methods and approaches are suitable to generate actionable knowledge for coastal governance?; (3) what obstacles to knowledge co-production exist for early-career researchers (ECRs) and how can they be overcome? The RQs are addressed in five publications. For answering RQ1, the dissertation applies a research synthesis to bring together common themes and challenges documented in resilience, climate change and environmental governance literature. For answering RQ2, different methods and approaches for generating actionable knowledge are proposed and tested using a case-study in the SES of Algoa Bay, South Africa. These include (i) the analysis of stakeholder agency; (ii) the application of a stakeholder analysis; and (iii) the combination of a capital approach framework, and fuzzy cognitive mapping. Finally, for answering RQ3, the thesis provides a perspective on the obstacles that especially ECRs face, and actions that are needed to create the conditions under which knowledge co-production processes can be successful. This is done by applying a multi-method approach combining an online survey and workshop targeted at ECRs in the marine sciences. Key findings suggest that system and transformative knowledge are particularly important when applying the concept of resilience in coastal governance to generate actionable knowledge. The different methods and approaches that are proposed and tested contribute to generating both system and transformative knowledge. Firstly, they provide an overview of the capacities of different stakeholders to act, shed light on current collaboration and knowledge exchange, and enable the identification of different governance processes for coastal governance and climate change adaptation (system knowledge). Secondly, results have implications for how to improve knowledge exchange and identify leverage points that can enhance overall governance performance, thus providing recommendations on actions and processes that can enhance climate resilience in the case-study area (transformative knowledge). It is also highlighted how knowledge co-production can contribute to generating system and transformative knowledge together with stakeholders, and what actions are needed to build the capacities to translate knowledge into action. Additionally, the findings of this dissertation put forward actions that are needed at different organisational levels of the academic system to facilitate knowledge co-production processes with stakeholders involved in coastal governance. The results of this dissertation have implications for stakeholders and decision-making in the case-study area, as well as for environmental governance, climate change adaptation and broader sustainability research. Implications for stakeholders include recommendations for implementing formal commitments to share climate information across levels and sectors, establishing the role of information providers in the municipality, and reinforcing human capital within the local municipality in Algoa Bay. Findings also suggest the need for a more integrated approach to climate change adaptation in coastal planning and management frameworks. It also suggests that the conservation of environmental assets presents an important bottleneck for resilience management and needs to be further prioritised within decision-making. Implications for research include the applicability of methods beyond the context of this dissertation; a more actionable concept for approaching resilience in (coastal) governance systems; and a more critical reflection on how transformative research is conducted, and what academic foundation is needed so that it can fulfil its societal goal.
System- und handlungstheoretische Überlegungen zur Führung von kleinen und mittleren Unternehmen
(2005)
Abstract Es ist ein verbreitetes Vorurteil, dass kleinere Unternehmen weniger gut geführt werden als größere Unternehmen. Empirische Unterstützung erfährt diese Auffassung durch Erhebungen, die zeigen, dass kleinere Unternehmen das vorhandene betriebswirtschaftliche Instrumentarium nicht in gleichem Umfang nutzen wie größere Unternehmen. Der vorliegende Beitrag zeigt, dass dieser Tatbestand nichts über die Qualität der Unternehmensführung aussagt. Die Unternehmensgröße schafft zwar unterschiedliche Handlungsvoraussetzungen. Die Fähigkeit effiziente Handlungsstrukturen zu entwickeln bleibt davon jedoch unberührt.
Der massive Ausbau der Photovoltaik (PV) stellt das deutsche Stromversorgungssystem vor Herausforderungen. Es gilt, die Stromerzeugung aus PV dem Bedarf anzupassen, Netzüberlastungen durch Solarstrom zu verhindern und den Strom in den Markt zu integrieren. Diese Arbeit untersucht, inwiefern dezentrale Stromspeicher als Lö-sungsansatz zur Bewältigung dieser Herausforderungen geeignet sind und inwieweit der derzeitige Rechtsrah-men diesen Ansatz fördert. Es zeigt sich, dass dezentrale Speicher einen Beitrag zur System- und Marktintegrati-on der PV leisten könnten, die rechtliche Förderung aber unzureichend ist, um dieses Potential auszuschöpfen.
Systemanalyse für Softwaresysteme ist ein Manuskript zum Selbststudium und zur Begleitung von Lehrveranstaltungen. Es vermittelt eine Einführung in die Systemanalyse in diesem Informatik-Kontext. Systemanalyse wird dargestellt als ein zielorientiertes Vorgehen mit vielfältigen Konkretisierungs- und Abstraktionsaktivitäten. Die Vorgehensweise wird anhand von Beispielen erläutert.
Systemnahe Programmierung
(1999)
Im Mittelpunkt der Systemprogrammierung steht die Entwicklung, Anpassung, parametergesteuerte Generierung und Betreuung der gesamten Betriebssoftware eines DV-Systems sowie eine Unterstützung bei der Anpassung von Basissoftware und Anwendungssoftware an ein Betriebssystem. Der vorliegende Text beinhaltet folgende Themen: Beschreibung grundlegender Aspekte von Rechnerarchitektur, Sprachkonzepte höherer Programmiersprachen, systemnahe Aspekte der Programmierung, Konzepte der objektorientierten Programmierung etc.
Als Fallstudie wird im ersten Paper der Einsatz der Szenarioanalyse als ein zentrales Element des Forschungsdesigns im Projekt „Sustainable University“ beleuchtet. Mit einem formalen Ansatz wurden Szenarien zum zukünftigen Umfeld der Hochschullandschaft entwickelt. Dieses Paper zeigt detailliert die notwendigen Denkschritte bei der Szenarioentwicklung auf und hilft zu verstehen, an welchen Punkten Integrationsschritte in Bezug auf Wissensarten und Perspektiven unterstützt und geleistet werden und somit auch (soziale) Lernprozesse gefördert werden können. Ferner werden die konkreten Ergebnisse der Szenarioanalyse vorgestellt und diskutiert. Zur Untersuchung von Lerneffekten wird die Methode der Szenarioanalyse in einen formalen Bildungskontext transferiert. Das zweite Paper leistet einen konzeptionellen Beitrag. Einleitend werden spezifische individuelle Kompetenzen diskutiert, die aus der Perspektive der Bildung für eine nachhaltige Entwicklung zum Umgang mit dem Klimawandel als komplexes Nachhaltigkeitsproblem und zu einer aktiven Teilnahme an Transformationsprozessen der Gesellschaft wichtig sind. Die Kompetenzen, wie proaktives Denken, der Umgang mit Unsicherheiten und unterschiedlichen Wissensbeständen sowie das vernetze Denken konnten hier beschrieben werden. Anschließend werden zwei Forschungsmethoden, der Syndromansatz und die Szenarioanalyse, für den Kontext der formalen Bildung nutzbar gemacht, und es wird theoretisch abgeleitet, wie in diesen Lernsettings die eingangs identifizierten Kompetenzen gefördert werden können. Die Szenarioanalyse bietet beispielsweise beim Denkschritt der Entwicklung von Zukunftsprojektionen großes Potential für Reflexionsprozesse oder die Integration von Wissen und Perspektiven zur Förderung der Kompetenz des proaktiven Denkens in Alternativen. Die diskursive Bewertung von Konsistenzen während der Szenarioerstellung birgt ähnliches Potential zur Förderung des vernetzten Denkens. Im dritten Paper wird ein Messinstrument für die Kompetenz des vernetzen Denkens (systems thinking) entwickelt. Es leistet einen empirischen Beitrag zur Lehr-Lernforschung, respektive zur Kompetenzmessung im Bereich der BNE. Dieses Instrument erfasst mit Hilfe eines Similarity Judgment Tests (SJT) den Grad der Vernetzung von Konzepten eines bestimmten Kontextes, in dem konkreten Fall von Aspekten des Klimawandels. In einer prä-post-Studie wurden zwei Kontroll und zwei Versuchsgruppen, die an dem zuvor genannten Lernsetting im Rahmen von Seminaren an der Leuphana Universität Lüneburg teilgenommen haben, empirisch begleitet. Auch wenn keine statistisch signifikanten Veränderungen des vernetzten Denkens der Teilnehmenden nachgewiesen werden konnten, bedeutet das nicht, dass die zuvor abgeleiteten Einflüsse der Szenarioanalyse widerlegt sind. Hier sind weitere Studien und die Weiterentwicklung des Messinstruments nötig. Zudem wurde nur ein Teil möglicher Einflüsse auf die Kompetenzentwicklung untersucht. Für die Szenarioanalyse als Lernsetting lässt sich schlussfolgern, dass zum einen der Moderation von Reflexions- und Diskussionsprozessen während unterschiedlicher Phasen eine sehr wichtige Rolle zukommt und sie einen wesentlichen Einfluss auf Lernprozesse hat. Zum anderen ist den Phasen, in denen Lernen stattfinden kann, genügend Zeit einzuräumen, so dass transdisziplinäre oder interdisziplinäre Forschungsprozesse mit der Methode Szenarioanalyse auch das Potential für Lernprozesse entfalten können. So kann mit Hilfe der Szenarioanalyse ein Setting geschaffen werden, in dem individuelle mentale Modelle und Handlungsmuster hinterfragt und Kompetenzen im Umgang mit komplexen Problemen gefördert werden, und somit individuelles und soziales Lernen für eine nachhaltige Entwicklung stattfinden kann.
The transition of our energy system towards a generation by renewables, and the corresponding developments of wind power technology enlarge the requirements that must be met by a wind turbine control scheme. Within this thesis, the role of modern, model-based control approaches in providing an answer to present and future challenges faced by wind energy conversion systems is discussed. While many different control loops shape the power system in general, and the energy conversion process from the wind to the electrical grid specifically, this work addresses the problem of power output regulation of an individual turbine. To this end, the considered control task focuses on the operation of the turbine on the nonlinear power conversion curve, which is dictated by the aerodynamic interaction of the wind turbine structure and the current inflow. To enable a power tracking functionality, and thereby account for requirements of the electrical grid instead of operating the turbine at maximum efficiency constantly, an extended operational range is explicitly considered in the implemented control scheme. This allows for an adjustment of the produced power depending on the current state of the electrical grid and is one component in constructing a reliable and stable power system based on renewable generation. To account for the nonlinear dynamics involved, a linear matrix inequalities approach to control based on Takagi-Sugeno modeling is investigated. This structure is capable of integrating several degrees of freedom into an automated control design, where, additionally to stability, performance constraints are integrated into the design to account for the sensitive dynamical behavior of turbines in operation and the loading experienced by the turbine components. For this purpose, a disturbance observer is designed that provides an estimate of the current effective wind speed from the evolution of the measurements. This information is used to adjust the control scheme to the varying operating points and dynamics. Using this controller, a detailed simulation study is performed that illustrates the experienced loading of the turbine structure due to a dynamic variation of the power output. It is found that a dedicated controller allows wind turbines to provide such functionality. Additionally to the conducted simulations, the control scheme is validated experimentally. For this purpose, a fully controllable wind turbine is operated in a wind tunnel setup that is capable of generating reproducible wind conditions, including turbulence, in a wide operational range. This allows for an assessment of the power tracking performance enforced by the controller and analysis of the wind speed estimation error with the uncertainties present in the physical application. The controller showed to operate the turbine smoothly in all considered operating scenarios, while the implementation in the real-time environment revealed no limitations in the application of the approach within the experiments. Hence, the high flexibility in adjusting the turbine operating trajectories and structural design characteristics within the model-based design allows for efficient controller synthesis for wind turbines with increasing functionality and complexity.
This cumulative dissertation deals with the association between corporate governance, corporate finance and corporate tax avoidance in four scientific articles. The aim of this dissertation is to explain corporate tax avoidance by (a) focusing on corporate governance institutions as determinants of tax avoidance and (b) focusing on financial consequences of tax avoidance. Due to the close association between corporate governance and the concept of corporate social responsibility (CSR), the relationship between CSR and tax avoidance is also addressed. The first article using structured literature review methodology, analyzes extant research on the association between corporate governance and tax avoidance based on stakeholder-agency theory. However, also classical principal-agent theory is taken into account as its classical foundation. The first article identifies a number of open research questions and thereby serves as a theoretical basis for the subsequent articles. The second article also using structured literature review methodology, analyzes extant research on the association between CSR and tax avoidance. This article is also based on stakeholder-agency theory and identifies open research questions. The third article based on results of the first article, investigates tax avoidance by German private family firms as a specific variant of corporate governance, using an empirical quantitative approach. The article finds that (a) German private family firms avoid more tax than non-family firms, that (b) tax avoidance is positively associated with the capital stake of the family and that (c) tax avoidance is positively associated with the number of shareholders in both family and non-family firms. Results reinforce that corporate tax avoidance is associated to conflicts among the shareholders of private firms. The fourth article investigates the cost of debt of German public firms as a function of tax avoidance and tax risk. The article finds that (a) tax avoidance is negatively associated to the cost of debt, that (b) tax risk is positively associated to the cost of debt and that (c) the association between tax avoidance and the cost of debt becomes negative when a high level of tax risk is present.
Members of Western organizations differ in various diversity attributes. In response, research aims to provide evidence-based recommendations on how to effectively manage diversity in teams. Within diversity research, the diversity faultlines approach has been particularly fruitful. It considers the impact of the alignment of multiple diversity attributes in teams. Strong diversity faultlines are associated with the emergence of relatively homogeneous subgroups in teams and have an overall negative impact on team processes and outcomes. This dissertation investigates factors that mitigate the detrimental consequences of strong diversity faultlines in teams, namely pro-diversity beliefs. It extends faultline literature beyond the conventional focus on processes and outcomes related to team members by emphasizing the leaders' perspective. The three empirical papers included in this dissertation systematically examine how strong pro-diversity beliefs can help unleashing the positive effects of team diversity despite strong faultlines. The first paper highlights the role of leaders' pro-diversity beliefs in mitigating the negative impact of diversity faultlines on two team processes: perceived cohesion and social loafing. Moreover, it compares the impact of socio-demographic faultlines (based on gender and age) and experience-based faultlines (based on team tenure and education level). Data was collected in a multisource field sample with 217 team members nested in 44 teams and the corresponding leaders. The second paper takes the impact of members' pro-diversity beliefs into account. It examines whether the impact of sociodemographic faultlines on performance is contingent on leaders' and members' pro-diversity beliefs. Moreover, the research group assumed that aggregate LMX would mediate this relationship. In a multisource data set obtained from 41 teams with 219 members and the corresponding leaders working for the German Ministry of Foreign Affairs, the investigators found partial support for their hypotheses. As expected, the impact of strong socio-demographic faultlines on diplomats' performance was least negative when both leaders and members held strong pro-diversity beliefs. The third paper zooms into processes and outcomes related to team leaders. It investigates how leaders' pro-diversity beliefs and their perceptions of members' prodiversity beliefs in teams with strong socio-demographic faultlines impact leaders´ task role assignment, performance expectation, and motivation. The research group conducted two experimental studies with students, one in Germany (N=55) and one in the US (N=134). Findings showed that strong pro-diversity beliefs held and perceived by leaders made them assign task roles that cross-cut rather than aligned with the subgroup structure created by faultlines. Moreover, leaders' perceptions of members' pro-diversity beliefs, but not their own beliefs, had a positive impact on their motivation, mediated by their performance expectation.
This cumulative thesis extends the econometric literature on testing for cointegration in nonstationary panel data with cross-sectional dependence. Its self-contained chapters consist of two publications and two publication manuscripts which present three new panel tests for the cointegrating rank and an empirical study of the exchange rate pass-through to import prices in Europe. The first chapter introduces a new cointegrating rank test for panel data where the dependence is assumed to be driven by unobserved common factors. The common factors are first estimated and subtracted from the observations. Then an existing likelihood-ratio panel cointegration test is applied to the defactored data. The distribution of the test statistic, computed from defactored data, is shown to be asymptotically equivalent to that of a test statistic computed from cross-sectionally independent data. The second chapter proposes a new panel cointegrating rank test based on a multiple testing procedure, which is robust to positive dependence between the individual units' test statistics. The assumption of a certain type of positive dependence is shown by simulations not to be violated in panels with dependence structures commonly assumed in practice. The new test is applied to find empirical support of the monetary exchange rate model in a panel of eight OECD countries. The third chapter puts forward a new panel cointegration test allowing for both cross-sectional dependence and structural breaks. It employs known individual likelihood-ratio test statistics accounting for breaks in the deterministic trend and combines their p-values by a novel modification of the Inverse Normal method. The average correlation between the probits is inferred from the average cross-sectional correlation between the residuals of the individual VAR models in first differences. The fourth chapter studies the exchange rate pass-through to import prices in a panel of nineteen European countries through the prism of panel cointegration. Empirical evidence supporting a theoretical long-run equilibrium relationship between the model's variables is found by the newly proposed panel cointegration tests. Two different panel regression models, which take both cointegration and cross-sectional dependence into account, provide most recent estimates of the exchange rate pass-through elasticities.
In this paper, we conduct a pan-European efficiency analysis to investigate the performance of European railways with a particular focus on economies of vertical integration. We test the hypothesis that integrated railways realize economies of scope and, thus, produce railway services with a higher level of efficiency. To determine whether joint or separate production is more efficient, we apply a Data Envelopment Analysis super-efficiency bootstrapping model which relates the efficiency for integrated production to a reference set consisting of separated firms which use a different production technology. We find that for a majority of European railways economies of scope exist.
The effects of habitat fragmentation and land use changes are usually studied by relating patterns of genetic diversity and differentiation to environmental factors, habitat history, landscape structure, or to a combination thereof. However, these three drivers are rarely addressed simultaneously. In addition, these studies are usually carried out in conservation-driven contexts, and therefore tend to concentrate on hyper-fragmented landscapes and on rare or endangered species. However, how habitat fragmentation and land use affect widespread species in more typical landscapes has not been fully investigated. This thesis addresses these two gaps. Abax parallelepipedus, a flightless ground beetle with low dispersal power, was used as a model species to test how environmental factors, habitat history, and landscape structure affect genetic diversity and genetic differentiation in three study regions located across Germany. Although all of the study regions represent fairly typical rural landscapes for central Europe, each consisting of a complex matrix of land uses, they differ from one another in terms of environmental factors, habitat history, and landscape structure, and thus can serve as three test cases. In the first stage of the work, the investigator identified polymorphic microsatellite loci which could potentially be used to study genetic diversity and differentiation in A. parallelepipedus. She then developed PCR and genotyping protocols for two suites of loci, in the end selecting to use the set of 14 fully multiplexed loci for the study. After having developed the needed study system, she genotyped over 3300 beetles from 142 study sites. In her investigation of how environmental factors and habitat history affect genetic diversity and genetic differentiation, and found that genetic diversity was being driven by variables that could be related to population sizes rather than by habitat history. She also did not find evidence of an influence of habitat history on the genetic differentiation patterns. Although populations of A. parallelepipedus in the past were probably smaller due to deforestation, they apparently remained large enough to prevent rapid genetic drift. In addition, the researcher carried out a landscape genetics analysis of the genetic differentiation patterns found in each of her study regions, in which she examined the relationship between genetic differentiation and landscape structure. She tested whether she could find patterns of isolation by distance, isolation by resistance, or isolation by barriers in the study regions. No effects of land use or of fragmentation were found. Based on the importance of population sizes found in the previous study, combined with the beetle's known avoidance of non-wooded areas and its inability to cross roads, the investigator concludes that although there is probably little gene flow across the study regions, large population sizes are preventing the rapid development of genetic differentiation. Models simulating the development of genetic differentiation over time in populations of different starting sizes support this conclusion.
Agricultural production of smallholder farmers in Myanmar is facing soil fertility degradation and in consequence, crop yields decline due to the imbalances of nutrient supply. In most cases, all above ground biomass is removed from the fields after harvesting the crops and during land preparation for the next crop. Higher temperatures also stimulate the higher mineralisation rates and released mineral nutrients are lost from fallow lands before sowing the next crops. Regarding the addition of mineral fertilizers, except for cash crops, farmers are reluctant to apply fertilizers for the crops that are sown for household’s self-sufficiency. In the Dry Zone, irrigated agriculture is available in recent years and farmers could overcome water scarcity through irrigation. With the availability of irrigation water, farmers could prolong the cropping period, nevertheless crop yields are decreasing year by year. In recent decades, research findings are indicating the benefits of biochar application for soil fertility improvement and food security. Smallholder farmers can produce biochar from agricultural by-products such as pigeon pea stems, cotton stems and rice husks by using biochar stoves. Large-scale production is possible by producing both biochar and thermal energy simultaneously, such as getting rice husk biochar and producing thermal energy by burning rice husks. By those means, environmental pollution due to the smokes from stubble burnings and the health hazards from smokes arise from kitchens can also be reduced. Present research was conducted to test the effects of the application of biochars produced from different crop residues together with NPK fertilizers on crop yields and soil properties in the rice-chickpea-cotton cropping system of the Central Dry Zone area of Myanmar during 2012 and 2013 cropping seasons at Shwe Daung Farm, Mandalay Division, Myanmar. Effects of biochar applications in combination with NPK fertilizers were compared with NPK fertilizer (without biochar) application and the control (without biochar and NPK fertilizers). Biochars used in the experiments were produced from three kinds of locally available raw materials (rice husk, rice straw and, pigeon pea stem) at temperature above 550°C by using a kiln made from a 200-Liter diesel barrel. Field experiments were conducted on sandy loam soil in the Central Dry Zone of Myanmar. After harvesting rice in 2012, chickpea was sown without application of both organic and inorganic fertilizers. After harvesting chickpea in 2013, cotton was sown on the same experimental plots. Treatments were rice husk biochar (Rh) 20 Mg ha-1 + NPK fertilizers; rice straw biochar (Rs) 20 Mg ha-1 + NPK fertilizers; pigeon pea stem biochar (Ps) 20 Mg ha-1 + NPK fertilizers; rice husk biochar and farmyard manure mixture (Rh biochar + FYM) 10 Mg ha-1 + NPK fertilizers; NPK fertilizers (without biochar); and the control (without fertilizer and biochar). Biochar weights represented fresh biochar weights. Equal rate of NPK fertilizers were applied in all treatments. However, fertilizer rates were different with respect to the crops. In rice experiment, 100:50:50 kg ha-1 rate of Urea (N): Triple Super Phosphate (P): Muriate of potash (K) was applied. In cotton experiment, 100:30:117 kg ha-1 rate of Urea (N): Triple Super Phosphate (P): Muriate of potash (K) was applied. Crop growth data, yield component data and yield data of each treatment were recorded. Soil samples from topsoil (0-0.2 m) were taken before starting the experiments, after harvesting rice and cotton, respectively, and analysed. A biogeochemical model, denitrification decomposition (DNDC) model, was used to estimate soil organic carbon storage and greenhouse gas emissions during crop growing seasons and to quantify the long-term impact of biochar applications on rice, chickpea and cotton yields.The results from soil analyses indicated that although initial soil pH was at 8.0 and pH values of biochars ranged between 8.0 and 10.0 soil pH after two years of biochar application did not increase. pH values were below 8.0. That value was lower than initial soil pH. That could be due to the effect of the change of cropping system from upland to lowland rice cultivation and the effects of biochar additions to the alkaline sandy loamy soil of the experimental site. Although total exchangeable cation value was not significantly different among the treatments, compositions of major cations were significantly different among the treatments. Exchangeable potassium increased in Rs biochar + NPK applied soils. Exchangeable sodium increased in control, and conventional NPK fertilizer applied soils. Reduction of soil bulk density from 1.8 g cm-3 to 1.6-1.7 g cm-3 occurred in biochar treatments compared to control and conventional NPK fertilizer application treatments. Positive changes of total carbon and total nitrogen of soils were found in biochar treatments compared to control and conventional NPK fertilizer application. Application of pigeon pea stem biochar + NPK fertilizers showed the highest crop growth and the highest yield in rice. The highest chickpea yield was obtained from the plot that applied rice husk biochar + NPK fertilizers. Cotton crop growth and yield was the highest in rice husk biochar and farmyard manure mixture + NPK fertilizer application. The lowest crop growth and yield was obtained from the control in cotton. The results of this study suggested that biochars from different biomass materials had different effects on soil properties and crop yields under different growing conditions and cultivated crops. Although the applied biochars had a high pH, soil pH did not increase after biochar applications. The growth and yield of tested crops were higher than that of the control and conventional NPK fertilizer application. Rice husk biochar and farmyard manure mixture + NPK fertilizer application can be assumed as a suitable soil amendment application under upland crop cultivation. Pigeon pea stems biochar + NPK fertilizers should be applied in rice cultivation. Rice husk biochar + NPK fertilizers and rice husk biochar-farmyard manure mixture + NPK fertilizers showed as the appropriate biochar soil amendments for the study area compared to rice straw biochar + NPK fertilizers and pigeon pea stem biochar + NPK fertilizers. Application of these biochars increased total exchangeable cations, reduced bulk density, increased organic carbon, regulated soil pH and, can easily be accessed by smallholder farmers by promising crop yields for sustainable agricultural production. Rice straw biochar + NPK fertilizers and pigeon pea stem biochar + NPK fertilizers also showed positive influences on soil fertility and crop growth. However, extensive application of those biochars might require large-scale productions and distributions. To obtain the detail information regarding the impact of biochar application on the agro-ecosystem and surrounding atmosphere, further research activities may need to carry out under different agricultural production conditions. When model fitness was tested, it was found that DNDC model was fit for the simulation of crop yields and soil organic carbon under the conditions of the experimental site. Simulation of soil organic carbon dynamics and crop yields for 30 years and 50 years after the addition of biochars in combination with NPK fertilizers showed that such applications could maintain the crop yields at the same level up to 50 years. That could maintain soil organic carbon at a level higher than conventional NPK fertilizer application. Regarding the simulation of GHGs emissions, the model simulated nitrous oxide emission close to actual emissions of agricultural soils of Myanmar. Simulated CH4 emissions from control and conventional NPK fertilizer application variant were consistent with the well-known emissions of Myanmar rice fields. To confirm the accuracy of simulated CH4 emissions from biochar applied soils, it may need field investigations and validations of model results. Simulated effects of rice husk-, rice straw- and pigeon pea stem fresh biomass applications and that of rice husk-, rice straw- and pigeon pea stem biochar applications on rice, chickpea, cotton yields and soil organic carbon (SOC) were compared. Objective of this simulation was to compare the effects of fresh biomass-applications and the application of biochars produced from the same biomass on crop yields and SOC by using DNDC model. The results showed that simulated rice yields of rice husk biochar and rice straw biochar applications were 33% and 31%, respectively, higher than that of pigeon pea green manure applications. However, simulated rice yield from pigeon pea stem biochar application was 4% higher than that of iv pigeon pea stem green manure application. Simulated chickpea yield from pigeon pea green manure treatment was the highest among all of biochar and biomass applications. Simulated cotton yields obtained from fresh biomass applications were lower than that of biochar applications. In estimating the future yields, all crop yields from rice husk and rice straw biomass applications were lower than that of rice husk and rice straw biochar applications in the initial year of simulation. However, in the following years, the yields remained at the same level up to the end of simulated years. In pigeon pea stem green manure application, crop yields were higher than the other treatments since the initial year up to the end of simulated years. Simulated SOC was lower in fresh biomass applications compared to biochar applications.
European species-rich grasslands are threatened both by land use intensification as well as land abandonment. The studies shown in this thesis tested the possible use of ecological knowledge to ensure hay productivity whilst maintaining diversity of grasslands, with a view to informing ecological restoration. The overall approach was to understand interactions between plants, to study diversity effects on productivity, and mainly investigate how plant functional groups that arrive first in the system can create priority effects that influence community productivity both above- and belowground. A grassland field experiment was established and monitored for four years, in order to verify the effects of manipulating the order of arrival of different plant functional groups, as well as the sown diversity level on productivity and methane yield. The overall findings were: a) sowing legumes first created priority effects aboveground (higher biomass) and belowground (lower root length), plants invested less in roots and more in shoots, b) priority effects were more consistent below than aboveground, c) sown diversity did not affect aboveground biomass, d) the order of arrival treatments indirectly affected methane yield by affecting the relative dominance of plant functional groups. Since the researchers lack information on how legumes and non-legumes interact spatially belowground, (particularly related to root foraging) a controlled experiment was performed, using two grass species and one legume. The identity and location of the neighbours played a role in interactions, and the order plants arrived modulated it. When the focal species (grass) was growing with a legume it generally equated to the same outcome as not having a neighbour. Roots from the focal species grew more toward the legume than the grass neighbour, indicating a spatial component of facilitation. Since these studies involved root measurements, a method study was also conducted to verify how comparable and accurate are root length estimates obtained from different techniques. Results showed that the use of different methods can lead to different results, the studied methods did not have the same accuracy, and the automated methods can underestimate the root length. Overall, the results allow to conclude that different groups of plants arriving before others affected above and belowground biomass, roots may be key drivers during the creation of these priority effects, and interaction outcomes between plants depended on neighbour identity and location, modulated by the order they arrive in. The results suggest that priority effects can be used by sowing different species or plant functional groups at different time to steer a community to a desired trajectory depending on the restoration goal. However, there is a need to test contingency, potential, and long term impacts of such possible tools for restoration.