Diese Dissertation umfasst vier Aufsätze welche die Effekte von nicht-zufälliger Selektion betrachten. Im ersten Aufsatz wird analysiert welche Rolle die geänderte Zusammensetzung der Erwerbsbevölkerung für die Entwicklung der Lohnungleichheit spielt. Vollzeit-Erwerbstätige weisen zunehmend Episoden von Teilzeitarbeit und Erwerbsunterbrechungen in ihren Biographien auf. Dies hat maßgeblich zum Anstieg der Lohnungleichheit beigetragen. Der zweite Aufsatz betrachtet die Effekte von gesunkener Arbeitslosigkeit auf Lohnungleichheit.. Wenn sich die Selektion in Vollzeit oder Arbeitslosigkeit ändert, kann dies zu steigender Lohnungleichheit führen. Dies ist insbesondere dann der Fall wenn Personen neu in Beschäftigung kommen, die eine Negativauswahl der Erwerbsbevölkerung sind. Jedoch zeigt sich, als Resultat einer Analyse mit selektionskorrigierten Quantilsregressionen, dass diese veränderte Selektion nicht zum Anstieg der Lohnungleichheit beigetragen hat. Im dritten Aufsatz geht es um nicht-monotone Selektion bei Regression Discontinuity Designs (RDD). Die Annahmen, auf welchen RDDs beruhen, können verletzt sein wenn sich sowohl Individuen in die Maßnahmengruppe hinein, als auch aus ihr heraus selektieren. Der Aufsatz beschreibt diesen Selektionsmechanismus und zeigt seine praktische Relevanz. Zudem wird ein Spezifikationstest vorgestellt um das Problem im Vorfeld der Analyse zu erkennen. Der vierte Aufsatz untersucht Wählerpräferenzen für das Geschlecht politischer Kandidaten. Es wird analysiert ob das Zusammenspiel von Berufsinformationen und Geschlecht die geringere Repräsentation von Frauen erklären kann. Dazu wurde ein Feldexperiment durchgeführt. Es zeigt sich dass weibliche Kandidaten einen Stimmvorteil genießen solange keine Berufsinformationen angegeben sind. Sobald jedoch die Berufe der Kandidaten bekannt sind kehrt sich dies in einen Stimmvorteil für männliche Kandidaten um. / This thesis comprises four essays which study effects of non-random selection. The first essay analyzes the role of changes in labor force composition for the development of wage inequality among full-time workers. Of particular interest are the effects of increasingly common episodes of temporary part-time work and nonemployment among full-time workers. Such episodes, have contributed substantially to the rise in wage inequality. The second essay studies the effects of declining unemployment on inequality of wages. Changing selection over time between unemployment and full-time work could lead to increasingly diverse wages, particularly if sinking unemployment implies an influx of negatively selected workers into employment. However, results from a selection corrected quantile regression approach show that changing selection with respect to unobservables is not a contributor to the rise in wage inequality. The third essay studies non-monotonic selection in regression discontinuity designs (RDD). When similar numbers of individual select into and out of treatment simultaneously, the identifying assumption of the RDD can be violated. The essay describes the selection mechanisms and demonstrates it’s practical relevance. It then suggests an enhancement to the standard specification tests for RDDs, which can detect non-monotonic sorting in advance. The fourth essay studies voter’s valuation of candidate gender. It examines whether the presence of profession information coupled with voter preferences for stereotypical male occupations may explain part of the gender gap in parliaments. The analysis is conducted as a field experiment built into an exit-poll of voters in Germany in 2014. The results show a vote share bonus for women in the absence of profession information. Once voters know the profession of candidates, however, this changes towards a small edge for male candidates.

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Legume establishment is difficult on many moderately acid, infertile soils in the humid northeastern United States. Legume seedling vigor as influence by P, S, and Mo fertilization was studied in order to determine fertilizer needs for improved establishment. A Gilpin silt loam was fertilized with 0, 22, 67, and 201 mg P kg⁻¹ in combination with 0, 22, 67, and 201 μg Mo kg⁻¹ in a greenhouse experiment in 1983. Legumes studied in this experiment were red clover (<i>Trifolium pratense</i>), white clover (<i>T. repens</i>), and birdsfoot trefoil (<i>Lotus corniculatus</i>). Field experiments with red clover, birdsfoot trefoil, and flatpea (<i>Lathyrus sylvestris</i>) were initiated in the spring of 1983 and 1984 using 0, 50, 150, and 450 kg P ha⁻¹, 0 and 60 kg S ha⁻¹, and 0 and 874 g Mo ha⁻¹. Seedling vigor as measured by plant height, trifoliate leaf count, dry weight, and trifoliate leaf area increased the greatest in the greenhouse using 22 mg P kg⁻¹ relative to the higher rates of P fertilization. Seedling vigor without applied P was poor, which clearly indicated the essential need for P in the early stages of legume growth. Molybdenum applied at 201 μg kg⁻¹ increased the growth of the greenhouse grown legumes the greatest above the 0 μg Mo kg⁻¹ rate within each added P treatment. Seedling vigor however, was not enhanced with Mo fertilization until the P deficiency was corrected. Field established legumes increased in height and dry matter yield the most using 50 kg P ha⁻¹ with respect to the additional increments of applied P, but the increase was not as great as that obtained in the greenhouse using 22 mg P kg⁻¹, This was attributed to a higher extractable P level before fertilization within the field experiments. Sulfur fertilization generally did not enhance seedling vigor in the field studies; although, red clover yield was increased using 60 kg S ha⁻¹ in the 1984 field experiment, Molybdenum applied at 874 g ha⁻¹ increased seedling vigor as measured by plant height and yield in the field experiments with or without P or S fertilization. Phosphorus uptake and Mo concentrations were increased in the plant tissues with either P or Mo fertilization. / Master of Science / incomplete_metadata

Progress towards sustainability requires changes in our individual and collective behaviour. Yet, our fundamental understanding of behaviour in relation to environmental change remains severely limited. In particular, little attention has been given to how individual and collective behaviours respond to, and are shaped by, non-linear environmental change (such as ‘regime shifts’) and its inherent uncertainties. The thesis makes two main contributions to the literature: 1) it provides one of the first accounts of human behaviour and collective action in relation to ecological regime shifts and associated uncertainties; and 2) extends the incipient behavioural common-pool resource literature that acknowledges social-ecological dynamics and ecological complexity. The overarching aim of this thesis is to further advance an empirically grounded understanding of human behaviour in social-ecological systems. In particular, the thesis attempts to unravel critical social-ecological factors and mechanisms for the sustainability of common-pool resources. This is especially relevant for contexts in which livelihoods can be more directly threatened by regime shifts. The following methods are applied: behavioural economic experiments in the lab (with students; Papers I and II) and in the field (with small-scale fishers from four different communities in the Colombian Caribbean; Paper III), and agent-based modelling empirically informed by a subset of the lab experiments (Paper IV). Paper I tests the effect of an endogenously driven regime shift on the emergence of cooperation and sustainable resource use. Paper II tests the effect of different risk levels of such a regime shift. The regime shift in both papers has negative consequences for the productivity of the shared resource. Paper III assesses the effect of different degrees of uncertainty about a climate-induced threshold in stock dynamics on the exploitation patterns; as well as the role of social and ecological local context. Paper IV explores critical individual-level factors and processes affecting the simultaneous emergence of collective action and sustainable resource use. Results cumulatively suggest that existing scientific knowledge indicating the potential for ecological regime shifts should be communicated to affected local communities, including the remaining uncertainties, as this information can encourage collective action for sustainable resource use. Results also highlight the critical role of ecological knowledge, knowledge-sharing, perceived ecological uncertainties, and the role local contexts play for sustainable outcomes. This thesis enriches the literature on social-ecological systems by demonstrating how a behavioural experimental approach can contribute new insights relevant for sustainability. Overall, these insights indicate that, given the opportunity and the willingness of people to come together, share knowledge, exchange ideas, and build trust, potential ecological crises can encourage collective action, and uncertainties can be turned into opportunities for dealing with change in constructive ways. This provides a hopeful outlook in the face of escalating environmental change and inherent uncertainties. / <p>At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 3: Manuscript.</p>

There is concern that climate change may cause mismatches between timing of flowering and activity of pollinators (phenology). However, concluding that mismatches will occur, and have serious consequences for pollination services, requires assumptions that have not yet been tested. I begin by discussing a set of these assumptions, bringing past research into the context of mismatch. Briefly, the assumptions are that 1) dates of first-flowering or emergence (DFFE) correctly describe phenology (and therefore mismatch); 2) differences in DFFE represent the magnitude of mismatch; 3) advancement of DFFE will be the primary phenological change; 4) shifts will be random and independent for each species; 5) populations of plants and pollinators are “bottom-up” regulated by their mutualistic interactions; 6) all interactions are of similar strength and importance; 7) dispersal, and the spatial context of phenological mismatches can be ignored; and ecological processes including 8) phenotypic plasticity and adaptive evolution of phenology, 9) competition and facilitation, and 10) emergence of novel interactions, will not affect mismatches. I then describe novel experiments, which could help to account for some of these assumptions, clarifying the existence and impacts of mismatches. Next, I present an original field experiment on factors affecting seed set in an alpine meadow in the Coast Range of British Columbia, Canada. I found evidence contradicting the assumption that seed set is primarily limited by pollination. My data highlight the roles of phenology, temperature (degree-days above 15°C, and frost hours), and interactions with pollinators (mutualists) and seed-predators (floral antagonists) in driving patterns of seed set. Seed set of early and late-flowering species responded differently to a 400m elevation gradient, which might be explained by phenology of bumble bees. My data suggest that the consequences of mismatch may be smallest for plants that are fly-pollinated and self-fertile. Non-selfing, bee-pollinated species might be more prone to reproductive limitation through mismatch (affected by snowmelt and cumulative degree-days). Plants that are limited by seed-predators might be negatively affected by warming temperatures with fewer frost hours, and extreme events such as late-season frosts and hail storms can prevent plants from setting seed entirely. Overall, my work emphasizes the importance of complementing theory, data-driven simulations, and meta-analyses with experiments carried out in the field. / Graduate