The Dynamics of Food Availability in sub-Saharan Africa: An Endogenous Perspective on Food Production Systems
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- Department of Geography 
Food insecurity is a major challenge of our time: In 2015, 795 million people suffered from hunger worldwide. The eradication of hunger remains a target of high-level policy programs such as the United Nations’ Sustainable Development Goals. To date, research has contributed extensively to our understanding of the food security problem, its causes, and possible solutions. Within this literature, many studies used an approach based on and restricted to one discipline (e.g., soil science, plant breeding, or microeconomics). These studies have thus provided insights related to particular aspects of food security within specific disciplines. Taken together, the insights add up to a broader picture of food security related issues. However, such discipline-specific insights often failed to include important properties of food security that arise from its systemic and dynamic nature. Food security is one of several food system outcomes that result from the dynamic interaction of various parts of food systems, such as food production activities and socio-economic and environmental drivers. Feedback mechanisms that pass through different parts of food systems, as well as their non-linear interaction and their associated accumulation processes, contribute distinctively to the dynamic complexity of food systems and shape the development of food system outcomes over time. Nevertheless, the dynamic complexity of food systems has received little attention in recent food security literature. This dissertation enriches the food security literature by exploring the dynamic complexity of food availability in sub-Saharan Africa, the part of the world with the highest prevalence of undernourishment worldwide. There has been a long tradition of food availability policies aiming to increase food production in sub-Saharan Africa, such as fertilizer subsidy programs (FSPs), promotion of conservation agriculture, and knowledge dissemination. Despite numerous studies that evaluated these policies, little is known about how policy programs affect various parts of a food production system and how the interaction of subsystems determines the performance of the policy programs over time. Thus, a core objective of this dissertation is to improve current understandings of the dynamic complexity of food production systems and how this leads to insufficient food availability outcomes on different levels (e.g., farm and nation). A second objective is to evaluate food availability policies with respect to the dynamic complexity of food production systems. A third objective is to enrich the food availability debate in sub-Saharan Africa on several scientific levels, specifically the theoretical, conceptual, applied, and methodological levels. The objectives are addressed in four independent articles, for which system dynamics was used as the main methodological approach. System dynamics is especially suited for studies that address and investigate the dynamic complexity of food systems because it captures feedback mechanisms, accumulation processes, and non-linearity. The dissertation comprises a general introduction followed by four articles. The first article explores the systemic properties of food production systems in sub-Saharan Africa and their implications for the FSPs, which are among the most important food availability policies. The article develops a conceptual modeling framework for a national food production system in sub-Saharan Africa by using the causal loop diagramming method. Based on the framework, a system dynamics simulation model is formally specified and calibrated for the study case of maize production in Zambia. The analysis of the model revealed that FSPs are effective for enhancing maize availability in the short-term, but in the long-term they fail to build up stock levels of soil organic matter, which is an important systemic leverage point to increase food availability in a sustainable manner. The second article uses an illustrative modeling approach to uncover systemic properties that lead to persistently low levels of food availability in sub-Saharan Africa and thereby seeks to explain why some policies, despite their plausible potential, fail to ensure adequate food availability. The results suggest three key concepts for understanding the performance of food production systems and related food availability policies: (1) stock management of soil organic matter, (2) policy effort threshold, and (3) land use anticipation. These concepts help explaining why sub-Saharan African countries’ food production systems and related policies persistently underperform in the provision of enough food for the respective populations. The third article uses a system dynamics model as a point of departure to acquire data on dynamic decision-making by smallholder farmers in Zambia through a Cournot market experiment. Experiments based on Cournot markets allow the investigation of how competing participants allocate a given budget across economic activities. Such experiments typically follow standardized procedures. The article describes and discusses how the standard Cournot experiment procedures were adjusted to fit the context of rural Zambia. The fourth paper analyzes the decision data from Cournot field experiments, in which Zambian smallholder farmers repeatedly decided how to split a given budget between a short-term oriented maize production activity (fertilizer purchases) and a long-term oriented maize production activity (soil improvement). The results revealed that the Zambian farmers had a clear and significant bias towards the short-term production activity. Nevertheless, there were distinct differences in their decision strategies, which resulted in different production outcomes that in some cases depended on the interaction with strategies that other farmers used in the same market. Overall, the four articles in this dissertation contribute to the food availability debates in sub-Saharan Africa on a theoretical, conceptual, applied, and methodological level. The dissertation as a whole helps to conceptualize sub-Saharan African food production systems, expands theories (e.g., through the concept of anticipation of land use change), challenges common beliefs (e.g., that inorganic fertilizer is an inevitable means to increase food availability), shows that policies and decision strategies are subject to dynamic and endogenous interaction that can enhance or reduce food production, prioritizes prior knowledge based on systemic interaction (e.g., soil organic matter as an important leverage point), and expands existing methodologies (e.g., Cournot market experiments). Thus, besides the importance of discipline-specific knowledge, it advocates the complementary benefits of a system- based approach that incorporates the dynamic complexity of systems.
Består avArticle 1: Gerber A. (2016). Short-term success versus long-term failure: A simulation-based approach for understanding the potential of Zambia’s fertilizer subsidy program in enhancing maize availability. Sustainability, 8(10):1036. http://hdl.handle.net/1956/13119
Article 2: Gerber A. (Forthcoming). Why do some food availability policies fail? A simulation approach to understanding food production systems in south-east Africa. Systems Research and Behavioral Science. http://hdl.handle.net/1956/16966
Article 3: Lara-Arango D, Gerber A, Nyanga P and Kopainsky B. (2017). Cournot markets in the field: Dynamic decision-making in non-standard markets. Article accepted for the 35th International Conference of the System Dynamics Society, 16–20 July, 2017, Cambridge, MA, USA. http://hdl.handle.net/1956/16972
Article 4: Gerber A, Lara-Arango D, Nyanga P and Kopainsky B. (2017). How do Zambian smallholder farmers allocate their budget? Evidence of dynamic decision-making based on a Cournot field experiment. Article accepted for the 35th International Conference of the System Dynamics Society, 16–20 July, 2017, Cambridge, MA, USA. http://hdl.handle.net/1956/16971