Browsing by Subject "Klimaänderung"

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Agent-based modeling of climate change adaptation in agriculture : a case study in the Central Swabian Jura
(2014) Troost, Christian; Berger, Thomas
Using the MPMAS multi-agent software, the present thesis implements an agro-economic agent-based model to analyze climate change adaptation of agricultural production in the Central Swabian Jura. It contributes to the DFG PAK 346 FOR 1695 research projects dedicated to improve the understanding of processes that shape structure and functions of agricultural landscapes in the context of climate change at regional scale. In the context of this example, this thesis discusses, develops and tests novel approaches to deal with four notorious challenges that have so far hampered the empirical use of agent-based models for applied economic analysis: data availability, process uncertainty, model validity and computational requirements. The model is used to examine climatic effects on agriculture, changes in agricultural price responses and biogas support and agri-environmental policies illustrating the applicability of the model to adaptation analysis. The first part of the thesis is dedicated to a methodological discussion of the use of mathematical programming-based multi-agent systems, such as MPMAS, for the analysis of agricultural adaptation to climate change. It synthesizes knowledge about the potential impacts of climate change and processes of farmer adaptation and reviews existing agent-based models for their potential contribution to adaptation analysis. The major focus of the first part is a discussion of available approaches to model validation, calibration and uncertainty analysis and their suitability for the use with mathematical programming-based agent-based models. This discussion is based on four principles required to ensure the validity of conclusions drawn from modeling studies: (i) a transparent model documentation, (ii) that the invariant elements of the model can really be expected to be invariant between scenarios assessed, (iii) that empirical calibration of the model is limited to the extent warranted by available observation and knowledge about the expected error distribution, and (iv) that the effect of process uncertainty on the conclusions is evaluated and communicated. Based on these conclusions, generic extensions of the MPMAS toolbox are developed to allow the application of suitable approaches for validation and uncertainty analysis. The second part of the thesis describes the application of the newly developed methodology in the construction and use of the Central Swabian Jura model. The model focuses on an endogenous representation of heterogeneity in agent behavior, an empirical parameterization of the model, and an incorporation of climate effects on possible crop rotations and suitable days for field work besides the expected effects on yields. It extends the demographic, investment and land market components of MPMAS to improve the simulation of structural change over time. The model was used to analyze potential effects of climate change adaptation on agricultural production and land use in the study area. The results show that besides effects on yields also other climate change-induced effects on the conditions of agricultural production may have important impacts on land use decisions of farmers and deserve more attention in climate change impact analysis. Potential impacts of changes in the time slots suitable for field work and an additional rotation option are predicted to be comparable to the impact of the changes in yields predicted by a crop growth model. Results point to an expansion of wheat and silage maize areas at the expense of barley areas. The partial crowding out of summer barley by wheat area held for current price relations and is less strong at higher relative prices for summer barley. Price response analysis indicated that winter wheat production enters into a substitutive relationship with summer barley production under climate change conditions, while competition with winter barley area diminishes. This leads also to a higher elasticity of the wheat area with respect to relative summer barley prices. The model was then used to analyze biogas support through the Renewable Energy Act (EEG) and the support for grassland extensification and crop rotation diversification through the MEKA scheme. Especially simulated participation in crop rotation diversification is strongly reduced in the climate change scenarios, while the investments in biogas plants are slightly increased. The conditions established by the latest EEG revision imply that further development of biogas capacity will crucially depend on the existence of demand for excess process heat, because the alternative option of using high manure shares seems to be rather unattractive for farmers in the area according to the simulation results.
Biogenic Greenhouse Gas Emissions from Agriculture in Europe - Quantification and Mitigation
(2002) Freibauer, Annette; Zeddies, Jürgen
This dissertation analyses relevant potential mitigation strategies of biogenic greenhouse gases (GHGs) in the agriculture of the European Union (EU) in light of the Kyoto Protocol. It identifies where important sources and mitigation potentials are located and what uncertainty, environmental ancillary effects and costs are associated with them. Literature reviews are performed and methodologies for environmental assessment and GHG accounting are further developed. On this basis, GHG emissions are quantified and reduction potentials are assessed at European level. In 1995, European agriculture emitted 0.84 ± 0.29 Tg N2O, 8.1 ± 1.9 Tg methane (CH4) and 39 Tg ± 25 carbon dioxide (CO2), which adds up to 470 ± 80 Tg CO2-equivalents or 11% of the overall anthropogenic greenhouse gas emissions of the EU. The detailed methodology developed here adequately resolves regional specifics of agricultural conditions and reduces the methodological uncertainty in the estimates to half of the one in the official national inventories. European agricultural soils will at maximum sequester carbon in the order of 100 Tg a-1 CO2 over the coming years, which may also provide other environmental benefits. The biological potential of bioenergy in the EU allows to substitute for 400 to 800 Tg a-1 CO2-equivalents. From an environmental perspective, the use of perennials, especially of residues and woody biomass, is preferable to intensively grown annual crops. The biological potential for technical GHG reduction measures in EU agriculture is between 100 and 200 Tg a-1 CO2-equivalents. Promising measures promote the extensivation of arable cropping by reducing nitrogen inputs, technological innovation in animal husbandry, which is best accompanied by a further decline in animal numbers, as well as rewetting drained organic soils. Most measures will provide ancillary environmental benefits. Changing the socio-economic and political frame conditions may enhance the GHG mitigation potential.
Climate change adaptation, social networks, and agricultural extension reforms in Ethiopia
(2016) Tensay, Teferi Mequaninte; Bennewitz, Jörn
Research on the impact of climate change in sub-Saharan Africa shows that climate change is expected to cause an increased frequency of extreme events such as high temperature and rainfall intensity, droughts and floods, desertification, and spread of animal and human diseases. These extreme events are likely to have a negative impact on food security. Using the case of Ethiopia, this thesis analyses the role that social network and agricultural extension can play in enhancing farmers’ ability to adapt to climate change. The thesis builds on recent research, which has highlighted the role of social networks and extension in promoting adaptation to the negative impacts of climate change. Social networks between farmers can build community resilience and increase adaptation to climate change. They also affect technology adoption and climate change adaptation through social learning, joint evaluation of new technologies and collective action. Current research on social networks in Ethiopia has mainly focused on the effects of network size on technology adoption and there is no empirical study on which types of social networks matter the most, and how do such types of social networks matter for climate change adaptation. Agricultural extension is expected to facilitate climate change adaptation through training and education of farmers, enabling them to anticipate climate change and to update their knowledge, attitudes and adaptive capabilities in response to climate change. In addition to their well-established function of promoting technologies and natural resource management practices, agricultural extension services are expected to play new roles in building farmers’ social networks and supporting climate change adaptation strategies. There are various studies on agricultural extension reforms in Ethiopia, but there are still gaps in this literature, especially regarding the capacity of the extension service to promote adaptation to climate change and to promote social networks. The purpose of this thesis is, therefore, to fill these knowledge gaps and to contribute to the current debate on the dynamic links between climate change, social networks and extension reforms. The thesis combines quantitative and qualitative methods for analysis of three inter-related research topics. First, the thesis examines farmers’ vulnerabilities to climate change and the role of adaptation in increasing productivity at the household level. Second, it assesses how the different types of social networks are related with the adoption of sustainable land management practices for climate change adaptation. Third, by examining what works and what does not work well in the agricultural extension reforms in Ethiopia, the thesis investigates the interactions between climate change, social networks and extension reforms in Amhara region of Ethiopia. The thesis is based on a mixed methods approach. It combines a quantitative analysis, using World Bank data from a survey conducted in 2011 covering 1338 farmers. The analytical methods include a probit model, an OLS analysis and an endogenous switching regression model. Qualitative research methods included Focus Group Discussions (FGDs) combined with an individual scoring technique, and a Climate Vulnerability and Capacity Analysis. The study on climate change adaptation found that the effects of climate change and adaptation practices differ across agro-ecological zones and adopter groups. In the kolla agro-ecologies, the major hazards were drought, floods, and migration. In contrast, snowfall, landslides and crop diseases were the main hazards in the dega and woyna-dega agro-ecologies. Erratic rainfall, soil erosion and livestock diseases were common hazards to all agro-ecologies. Households’ responses to the hazards were differed across the different agro-ecologies. In the kolla agro-ecologies, the most common coping strategies were reducing the number of daily meals, migration, livestock selling and utilization of irrigation. In the dega and woyna-dega agro-ecologies common coping strategies included: changing consumption patterns; adopting drought resistant crops (sorghum and millet); sale of chickens, eggs, sheep, goats, eucalyptus trees; soil conservation and tree planting; zero grazing and water harvesting. In all agro-ecologies, local institutions support communal adaptation strategies such as communal water harvesting and irrigation schemes, reforestation, rangeland enclosure and prevention of soil erosion. The empirical results also revealed that farmers who implemented climate change adaptation strategies have significantly increased their food productivity and food security, compared to farmers who did not implement such strategies. The findings regarding the relationship between social networks and sustainable land management revealed that networks with relatives have a positive impact on planting trees, but the impact of such networks on soil conservation was found to be negative. This finding can be interpreted as an incidence of self-interested behavior, since farmers may plant trees as a means of securing land holdings. When farmers are faced with the risk of losing their land to relatives, due to common heritage, they prefer planting trees to soil conservation. Farmers can reclaim all their investment costs by cutting trees, should they lose their land holding rights to relatives. In contrast, it would be difficult to regain soil conservation investment costs in this case. Friendship networks were found to be insignificant in both planting trees and soil conservation, while neighborhood ties only had a significant association with tree planting. This suggests the potential contributions of friendship and neighborhood networks, which can significantly affect sustainable land management practices, but may remain untapped. The analysis of extension conducted as part of this thesis suggests that a uniform reform approach, as pursued in Ethiopia, does not fit well with the diverse agro-ecologies and extension challenges in the country. While the number of service providers increased substantially, they still lack skills, incentives and resources, which affect their work motivation and job performance. Moreover, the planning, monitoring and evaluation system was found not to be very effective in regularly assessing what has been achieved at the farmers’ training centers and what remains to be done in the future. Similarly, there is room to improve partnerships and linkages of actors, especially by including key actors that are currently missing. Based on the above findings, this thesis derived the following policy implications: 1. The potential capacity of schools and religious organizations in supporting climate change adaptation should be tapped. The case study identified agricultural extension, health extension, NGOs, cooperatives, indigenous institutions (Iddir, Kirre, Jiggie, Debo, Iquib), microfinance institutions, schools, local governments, youth and women groups as key institutions providing rural services. However, extension organizations, cooperatives/unions, local governments and NGOs were the only institutions providing services relevant for climate change adaptation. Surprisingly, important local institutions (schools and religious organizations) did not have any short or long term plans to support climate change adaptation efforts despite the fact that they have the social capital to plan and implement some communal strategies such as terracing and planting trees on communal lands. 2. The regional and national policies should support local climate change adaptation strategies. The study showed that adaptation efforts should not be left to only farmers and local governments. Regional and national policies should support the local adaptation strategies. It was found that the absence of communal land and natural resource use policies was encouraging farmers to over utilize natural resources, and the long delay in land use rights (certification) was discouraging farmers from making long term investments on their land (e.g., tree planting and soil conservation). Therefore, the findings suggest that it would be useful to promote the introduction of communal land and natural resource use policy and a speedy land certification process. 3. The potential contributions of social networks as alternative channels of extension services should be tapped. The findings revealed that funds for agricultural extension are declining and extension managers should look for alternative source of funding and move away from a “one-size-fits-all” thinking to a “best fit” approach. It needs to become a priority for the current extension system to better understand what types of social networks matter most for technology adoption. 4. The findings also indicate that extension reforms should consider current agricultural challenges, especially climate change. In dega and woyna-daga agro-ecologies, the main challenges were getting information on climate change related hazards (rainfall and temperature), commercial marketing (cooperative development, price and new markets), post-harvest handling (drying and storage technique). In the kolla agro-ecologies, the major problems were lack of dry land farming methods (contour plowing, mulching, strip farming, summer fallow, seedbed preparation and planning in rows). So far, the extension system is not geared towards addressing these different challenges, which calls for aligning the extension reforms to the different local farming systems. 5. It can also be derived from the findings of this study that the regional government should design a new incentive system for the extension service. The case study showed that current incentives are inconsistent with the regional goal of promoting commercially oriented agriculture. Service providers in the region were found to lack the soft skills, incentives and resources to provide commercially oriented services. This finding calls for designing a new incentive system, which may include better salary, improved career prospects, and recognition as well as incentives for extra work. Such provisions will motivate and enable frontline service providers. 6. The governance and management structures of the Agricultural Development Partners’ Linkage Advisory Councils (ADPLACs) should be redesigned. The case study revealed that when measured against indicators such as information sharing and feedback, joint planning, monitoring, evaluation and implementation, the linkages between farmers, NGOs and research institutes were very weak. This calls for redesigning the governance and management structures of the Agricultural Development Partners’ Linkage Advisory Councils (ADPLACs), which was responsible for facilitating the partnership and linkages of extension actors in the region. 7. The findings of this thesis also suggest that the roles of NGOs and the private sector in the provision of extension service should be enhanced. The case study found that key actors such as the private sector and NGOs were missing from effective provision of extension services. The private sector and NGOs may have a comparative advantage in activities such as provision of improved seeds, fertilizers, pesticides, vaccination, deworming and artificial inseminations. NGO and private sector engagement in these areas will allow the regional government to free up and reallocate funds to its broader extension strategies such as development of new incentive schemes, education and training, technical advisory services, sustainable natural resource management practices and organizing farmers to link them with new markets.
Climate change and agricultural structural change : the relevance for machinery use and acquisition in Germany
(2021) Mendoza Tijerino, Francisco Antonio; Berger, Thomas
This thesis is a contribution to the research project “Regional Climate Change,” funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG – Forschergruppe 1695 Regionaler Klimawandel). The projects objective was to learn about the vulnerability and sensitivity of typical land systems in Southwest Germany and identify suitable strategies for adaptation. The doctoral work contributes with empirical and methodological insights of farmers likely management adaptations in light of the farm managerial challenges arising from climate and structural change in Germany. The agricultural structure in Germany has strongly changed in the last 60 years. Where before numerous small-scale and labor-intensive farms were observed, it is now the place where fewer and highly mechanized farms contribute to agricultural production. The ongoing agricultural structural change in Germany is characterized by a trend in which many farms exit the agricultural sector, and the remaining --growth-oriented-- farmers take over the land, reorganize their farm business, and expand their operations. Nevertheless, this trend of farm growth, which is expected to continue in the future, poses significant challenges at the farm management level: Decisions on machinery use and acquisition play a crucial role in shaping the farm cost structure, and represent a critical element for maintaining competitiveness. Particularly for the expansion efforts, farm managers face a highly complex decision-making process to acquire the proper machinery capacities for field operations. Moreover, an additional factor will need to be considered for adequate decision-making: Climate change developments and the uncertainties associated with this process will likely increase the complexity of the farmers decision-making regarding the best reorganizational strategies towards farms expansion. Changes in the natural conditions for crop growth and development will likely result in management adaptations, e.g., changing the timing for fieldwork operations or changing land-use patterns. An analysis of the complex interactions and interdependencies between the environment and the farm system, on the one hand, and the resources and production possibilities available to the farm manager in the course of farm expansion on the other hand, require adequate tools of analysis. This work analyzes three dimensions of farm machinery management in the context of climate change and agricultural structural change. The first element of analysis corresponds to an examination of the sensibility of land-use and machinery investment decisions to climate change scenarios with the agent-based MPMAS model constructed for Central Swabian Jura in Southwest Germany. The Central Swabian Jura MPMAS model is a constitutive part of the bioeconomic modeling system MPMAS_XN. The MPMAS_XN system integrates the agricultural economic agent-based software MPMAS and the plant-soil modeling software Expert-N (XN) into a fully coupled system. The assessment of the sensibility and responsiveness of the MPMAS component revealed complex adaptation responses of land-use and machinery investment decisions as a result of shifted timing in fieldwork operations (e.g., harvesting or fertilization tasks). The second element of analysis corresponds to an examination of economies of size arising from farm machinery use and acquisition decisions in arable farms that follow a typical crop rotation practiced in Germany. For the analysis, a whole-farm multiperiod mathematical program implemented in the agent-based software MPMAS was employed. Optimizations were run and evaluated at a broad range of farm sizes and two distinctive distributions of availability of fieldwork days estimated for Southwest Germany. The results allowed observing patterns of optimal farm machinery demand and cost curves for several evaluated farm sizes and distributions of available fieldwork days distributions. The third main element of this work corresponds to a methodological contribution to the MPMAS_XN model system. Within this element, the implementation, functioning, and potential of an external theory-based MPMAS module are presented. The external module represents dynamics for joint machinery investments among simulated farm agents and serves as an enhancing methodological contribution for analyzing and representing farm machinery management in the agent-based software MPMAS.
Climate variability, social capital and food security in Sub-Saharan Africa : household level assessment of potential impacts and adaptation options
(2015) Assfaw, Tesfamicheal Wossen; Berger, Thomas
Climate variability and poor distribution of rainfall often causes serious agricultural production losses and worsens food insecurity. Given that the direct effects of climate change and variability are transmitted through the agricultural sector, improving farm households capacities to adapt to the adverse effects of climate-related shocks is an important policy concern. This thesis applied a stochastic Agent-based Model (ABM) that is capable of simulating the effects of different adaptation options by capturing the dynamic changes of climate and prices, as well as the dynamic adaptive process of different farm households to the impacts of these changes. The agent-based simulations conducted in this thesis address the special challenges of climate and price variability in the context of small-scale and subsistence agriculture by capturing non-separable production and consumption decisions, as well as the role of livestock for consumption smoothing. To ensure the reliability and usefulness of results, the model was validated with reference to land-use and overall poverty levels based on observed survey values. In particular, the study used disaggregated socio-economic, price, climate and crop yield data to quantify the impacts of climate and price variability on food security and poverty at the household level. Furthermore, the study explicitly captured crop-livestock interactions and the “recursive” nature of livestock keeping when examining the effects of climate and price variability. The thesis additionally examined how specific adaptation strategies and policy interventions, especially those related to the promotion of credit, improved seed varieties, fertilizer subsidy and off-farm employment, affect the distribution of household food security and poverty outcomes. In addition to impacts on household food security and poverty, the study further considered indirect impacts through changes in the price of agricultural inputs and livestock holding. In terms of coping strategies, the simulation results in this thesis show that the effects of climate and price variability on consumption are considerable, but smaller for those households with relatively large livestock endowments. In addition, the study also found that farm households with a large plantation area of eucalyptus were able to cope with the effects of variability. Therefore, our results suggest that self-coping strategies are important but not sufficient and should be complemented with appropriate policy interventions. In terms of policy interventions, the study found that policy intervention through the expansion of credit and fertilizer subsidy along with innovation through the promotion of new crop varieties that are resilient and adapted to local conditions are the most effective adaptation options for the case of Ethiopia. In addition, the simulation results underscore that adaptation strategies composed of a portfolio of actions (such as credit and fertilizer subsidy along with new technologies) are more effective compared to a single policy intervention. For Ghana, the study suggests that if expansion of production credit is complimented by irrigation, it can provide a way to achieve food security under climate and price variability. In order to design a best-fit intervention instead of a ‘one size fits all’ approach, it is important to capture the distribution of effects across locations as well as households. The great strength of this study is its agent-based nature, which enables exploration of how effects are distributed across farm households. The simulation results clearly show that poor farms are vulnerable to climate and price variability, under which they suffer food insecurity, while a small group of wealthy farms are better off due to higher prices achieved when selling crops. The result from this thesis further underscores the need for improving adaptive capacity, as a large proportion of farm households are unable to shield themselves against the impacts of price and climate variability. In what follows, the study further applied standard micro-econometric techniques to examine the role of social capital and informal social networks on consumption insurance and adoption of risk mitigating land management practices. In particular, the thesis provides evidence of the effects of different dimensions of social capital on the adoption of soil and water conservation practices across households holding different levels of risk-aversion. The results of the study underscore that social capital plays a significant role in enhancing the adoption of improved farmland management practices and suggests that the effect of social capital across households with heterogeneous risk taking behaviour is different. Finally, by combining household panel data, weather data, self-reported health shocks and detailed social capital information, the last section is able to analyze how social capital buffers some of the implications of weather shocks.
Communicating climate change : how proximising climate change and global identity predict engagement
(2018) Loy, Laura Sophia; Trepte, Sabine
The majority of scientists express an urgent need to limit climate change in order to ensure sustainable development, but our societies are not reacting decisively enough to achieve this goal. My research aims to understand how news about climate change can be communicated to convey scientific knowledge and support climate protection. Proximising climate change by focussing on local instead of global or remote consequences has been recommended as a promising communication strategy. The reasoning is that many people seem to perceive climate change as a phenomenon that affects mainly other people in far-off places (i.e., psychological socio-spatial distance). Proximising might bring climate change closer. However, the recommendation still lacked convincing empirical evidence. Thus, my research investigated the communication of proximity vs. distance in news coverage. Specifically, I examined the process assumed to be behind proximising effects, namely a reduction of the psychological socio-spatial distance of climate change, which might increase issue relevance and in turn promote climate protective behaviour and climate change knowledge. In Study 1 (N = 498), people were asked to what extent the news communicated climate change as something affecting mainly other people in distant locations. The more they perceived news communication as socio-spatially distant, the higher their psychological socio-spatial distance of climate change and the lower relevance they attributed to the issue. Perceived communicated socio-spatial distance was indirectly and negatively related with climate protective behavioural knowledge through higher psychological socio-spatial distance. Study 2 (N = 99) found no evidence that communicating socio-spatial proximity vs. distance of climate change in a news text influences psychological socio-spatial distance, relevance attributed to the news text, climate protective behaviour, and climate change knowledge. However, the test power was not sufficient to detect small effect sizes. In Study 3 (N = 508), proximising climate change in a news text decreased the psychological socio-spatial distance of climate change and indirectly and positively predicted climate protective behaviour as well as climate change knowledge through lower psychological socio-spatial distance and higher relevance attribution. While the indirect relations were small, stronger relations might arise if people repeatedly receive local information. I thus suggest that it is worthwhile to complement news about global climate change with reports about regional impacts. As a second objective, I aimed to illuminate whether the concept of a global identity helps to explain why proximising might not always be necessary or useful. I assumed that the more people identify with people all over the world, the more relevant they evaluate climate change to be and the more they are motivated to take climate protective action and acquire climate change knowledge. Moreover, I supposed that people with a strong global identity might evaluate climate change as relevant regardless of whether they perceive that the consequences mainly affect other people in distant places. In other words, a global identity might bridge the psychological socio-spatial distance of climate change. In Study 1, global identity positively predicted the relevance attributed to climate change and climate protective behaviour, as well as climate change knowledge indirectly through relevance attribution. In Study 2, the global identity dimension of self-investment positively predicted climate protective behaviour. However, global identity did not bridge the psychological socio-spatial distance of climate change in either study. I further reasoned that the negative relation between psychological socio-spatial distance and relevance attribution might be weaker if global identity is made salient. In other words, a salient global identity might bridge the psychological socio-spatial distance of climate change. In Study 3, before reading the news text, participants watched either a control video or a video showing a man dancing with people all over the world, which communicated a feeling of connectedness. While participants who received the control video evaluated the news text as less relevant as their psychological socio-spatial distance of climate change increased, there was no such relation among participants who received the connectedness video. Moreover, communicated proximity vs. distance in the news text did not indirectly predict climate protective behaviour and climate change knowledge in the latter group. This suggests that communicating connectedness might be a way to bridge the distance of climate change communication and render issues that are perceived as affecting mainly other people in far-off locations more relevant to recipients.
Extreme climate shock and locust infestation impacts in Ethiopia : farm-level agent-based simulation of adaptation and policy options
(2022) Ejeta, Alemu Tolemariam; Berger, Thomas
Extreme climate shocks have been a daunting problem for smallholder farmers in Ethiopia for a decade. In recent years, locust invasions in many parts of the country have become another livelihood challenge to the subsistence farming population who already lives in dire livelihood situations. These two compounding shocks can lead to total crop failure at the early crop development stage or any crop growth stage. They are creating a massive economic upheaval in rainfed-dependent countries particularly affecting the well-being of resource-poor subsistence farmers. To reduce the effect of recurring shocks, especially climate risks, farmers have been implementing different risk management strategies. In addition to farmer autonomous adaptation practices, the government has been supporting farmer climate adaptation efforts by designing different policy interventions. In locust-hit areas, government and non-governmental organizations have designed and implemented different locust relief programs aimed at reducing associated welfare losses. Whether farmers can adapt to the effects of climate shocks or not by autonomous adaptation and/or with policy support is an empirical policy question. Moreover, as there are no studies of locust impacts and locust relief programs evaluation, the degree of locust livelihood devastation and the roles of locust relief policy interventions in minimizing the effect of locust shock are policy concerns. To address these important and key empirical questions, this thesis applied a farm-level agent-based simulation model. MPMAS, a modeling framework developed at the University of Hohenheim for agent-based simulations, was applied to capture inseparable production and consumption decisions of subsistence farming households in the Central Rift Valley of Ethiopia. The modeling framework uses a whole-farm mathematical programming modeling approach to represent complex dynamics of farm household decisions where a set of constraints and their complex relationships are considered. This simulation model enables scenario-based policy analysis by comparing different climate, locust, and policy scenarios which is hardly possible using statistical and other reduced forms of econometrics models. Through establishing scenarios, the model helps to disentangle the pathways through which external shocks may affect the well-being of smallholder farmers. MPMAS has been extensively applied for policy simulations in different countries including Ethiopia. This thesis extends previous MPMAS applications in Ethiopia by including new features for Central Rift Valley (MPMAS_CRV). MPMAS_CRV was parameterized from the CIMMYT household survey augmented with CSA datasets and own field research. Smallholder farmers ex-ante considerations of risk management strategies for possible climate shock are explicitly captured in MPMAS_CRV to assess their role in climate adaptation and welfare improvements. As part of enhancing the adaptive capacity of farm households to recurring climate shocks, the effect of policy interventions such as better access to credit services and improved agricultural technology are quantified by establishing climate and policy scenarios. Similarly, the thesis quantified the impact of locust invasions on household welfare outcomes and their response to locust relief interventions including food or cash transfers complemented with inputs and livestock provisions. Locust simulation is one of the novelties of this research as it is the first study to explicitly capture the welfare effects of the desert locust and assess the roles of locust relief programs through the application of MPMAS. To enable climate and locust shock effects quantification and associated policy interventions, different simulation experiments were designed comprised of climate and locust shock frequencies and policy scenarios. The simulation experiments and analysis were performed using the computational resources of bwForCluster within the bwHPC infrastructure in the state of Baden-Württemberg, Germany. Before using MPMAS_CRV for policy simulations, its reliability was validated using land use, livestock holding, and amount of crop sales by comparing simulated against observed survey values. The validation results suggest that MPMAS_CRV can represent and reflect real-world conditions so that it is reliable to use for impact quantification and policy simulations. In addition to empirical validation, the thesis conducted a global uncertainty analysis to check the robustness of the simulation results under different parameter variations and combinations to minimize erroneous policy formulations. Uncertainty analysis results show that the model converges rapidly at 50 repetitions which implies that these model repetitions are enough to cover the model uncertainty space. In terms of extreme climate impacts and adaptations, the simulation results suggest that climate shocks affect the welfare of agents adversely to the extent that they face temporary food shortages, loss of discretionary income, and depletion of livestock assets. The welfare losses are similar for both with and without ex-ante measure scenarios which indicates that farm agents cannot adapt to extreme shocks by employing autonomous adaptations. After the shocks are over, the simulation results reveal that agents cannot recover income and livestock losses immediately even when they consider ex-ante measures in the planning for possible risks. This suggests that for resource-poor farm agents, income and assets recovery takes a longer period after perturbation which can lead to a long-term livelihood crisis and a poverty trap. But, according to the simulation results in this thesis, agents can recover from food shortage immediately after the shocks are over, as meeting minimum food requirements are an absolute priority for agents (which is also true with real-world subsistence smallholder farmers) over other competing goals. Credit and technology policy simulation analysis further depict that welfare losses are partly compensated compared to without policies. Welfare losses of agents are better compensated when credit and technology are used jointly than when they are implemented separately. Similarly, technology policy intervention is better in compensating welfare losses compared to credit policy. Though policy interventions have compensational effects in minimizing the losses, they cannot completely offset the negative effects of extreme climate shocks even when implemented jointly. Disaggregation of simulation results by resource endowments suggests that agents with higher baseline income (without policy) and farm size appeared to be relatively less affected by shocks, and benefit from policy interventions the most. Locust simulation results also suggest that locust shock leads to agent livelihood crisis and makes slower recovery of income and livestock assets rebuild without any relief intervention programs. Simulation of different locust relief policy interventions reveals that combined relief policy interventions appear to be superior in compensating welfare losses compared to individual relief interventions. When food or cash transfer is combined with inputs and assets the welfare losses are considerably reduced compared to the individual policy intervention. When asset recuperation is combined with other relief programs, livestock losses are substantially reduced which signifies the importance of asset support in building an asset base which has long-term benefits. Strengthening early warning systems by including seasonal weather forecasting has paramount importance to prevent the crisis of desert locust plague.
Impact of climate change on future barley (Hordeum vulgare L.) production in Ethiopia
(2022) Gardi, Mekides W.; Graeff-Hönninger, Simone
Summary Barley (Hordeum vulgare L.) is the fourth major cereal crop in the world, and it accounts for 8% of the total cereal production in Ethiopia based on cultivation location. Farmers may face unpredictable rainfall and drought stress patterns, such as terminal drought, in which rainfall ends before crops reach physiological maturity, posing a challenge to crop production. Furthermore, climate change is expected to reduce crop production/yield due to increases in carbon dioxide (CO2) and ozone (O3) concentrations, temperatures, and extreme climate events such as floods, storms, and heatwaves, highlighting the importance of taking action to develop climate-resilient cultivars and secure future crop production. Against this background, a meta-analysis study was conducted to synthesize and summarize to assess the overall effect of elevated CO2 (eCO2), and its interaction with nitrogen (N) and temperature on barley grain yield and yield components. A climate chamber experiment was carried out to identify the impacts of projected CO2 enrichment (eCO2) on a set of landraces and released cultivars of Ethiopian barley. The crop-climate modeling approach was used to simulate future climate change and to identify the impacts of climate change on selected barley genotypes and study locations in Ethiopia. Furthermore, adaption options were simulated and identified. Publication I, aimed to answer how eCO2 and its interaction with N and temperature affects barley yield at a global level. Peer-reviewed primary literature (published between 1991-2020) focusing on barley yield responses to eCO2, temperature, and N were searched on different search engines. The response of five yield variables of barley was synthesized and summarized using a meta-analysis technique. Different experimental factors which might affect the estimation of the response of barley yield to eCO2 were calculated. The results revealed that eCO2 increased barley yield components such as vegetative biomass (23.8%), grain number (24.8%), and grain yield (27.4%) at a global level. Barley vegetative biomass and grain yield were increased under the combination of eCO2 with the higher N level (151-200 kg ha-1) compared to the lower levels. Grain number and grain yield were increased when eCO2 combined with temperature level (21-25°C) this response was not evident. The response of barley to eCO2 was different among genotypes and experimental conditions. Publication II, the genetic diversity of Ethiopian barley was screened under eCO2 enrichment in a controlled exposure experiment. The experiment was conducted at the Institute of Landscape and Plant Ecology, the University of Hohenheim in 2019. A total of 30 (15 landrace and 15 released cultivars) were grown under two levels of CO2 concentration (400 and 550 ppm) in climate chambers. Plant-development-related measurements and water consumption were recorded once a week and yield was measured at the final harvest. A significant increment in plant height by 9.5 and 6.7%, vegetative biomass by 7.6 and 9.4%, and grain yield by 34.1 and 40.6% in landraces and released cultivars, respectively were observed due to eCO2. The effect of eCO2 was genotype-dependent, for instance, the response of grain yield in landraces ranged from -25% to +122%, while it was between -42% to 140% in released cultivars. The water-use efficiency of vegetative biomass and grain yield significantly increased by 7.9 and 33.3% in landraces, with 9.5 and 42.9% improvement in released cultivars, respectively under eCO2. Comparing the average response of landraces versus released Ethiopian barley cultivars, the highest percentage yield change due to eCO2 was recorded for released cultivars. However, higher actual yields under both levels of CO2 were observed for landraces. Publication III, Current and future climate change, its impact on Ethiopian barley production, and adaptation options were simulated using the DSSAT-CERES-Barley model. Climate change scenarios were set up over 60 years using Representative Concentration Pathways (4.5 and 8.5), and five Global Climate Models. The changes in Ethiopian climate and barley production were calculated from the baseline period (1981-2010). Different sowing dates, sowing densities, and fertilizer levels were tested as climate change impact mitigation strategies in a sensitivity analysis. The analysis of a crop-climate model revealed an increasing trend of temperature (1.5 to 4.9 °C) and a mixed trend of rainfall (-61.4 to +86.1%) in the barley-producing locations of Ethiopia. The response of two Ethiopian barley cultivars was simulated under different climate change scenarios and a reduction of yield up to 98% was recorded for cv. Traveler while cv. EH-1493 exhibited a reduction of up to 63%. Even though a similar trend was observed for most of the studied locations, cv. EH-1493 showed a yield gain of up to 14.7% at Holeta. The sensitivity analysis on potential adaptation options indicated that the negative effects of climate change could be mitigated by earlier sowing dates, with a 25% higher sowing density and a 50% higher fertilizer rate than the current recommendation. The results of the present dissertation show the change in the Ethiopian climate and its impact on barley production. Barley production could benefit from eCO2; however, the response varied among genotypes, additional stress, and experimental condition. A reduction of barley grain yield under different climate change scenarios was observed mainly due to increasing temperature. However, the reduction could be minimized through different adaptation options. The information from the current dissertation could be used to identify agro-economic implications of CO2 enrichment and climate variability on yield regarding appropriate genotype selection and adaptation of regional cropping systems (e.g., management and breeding strategies). Further experimental studies assessing crop production, nutritional quality, and adaptation options under multifactor climate conditions should be carried out to increase basic understanding and identify genotypes for future breeding programs.
Impacts of temperature increase and change in precipitation pattern on ecophysiology, biomass allocation and yield quality of selected crops
(2023) Drebenstedt, Ireen; Högy, Petra
Climate change poses a challenge for the production of crops in the twenty-first century due to alterations in environmental conditions. In Central Europe, temperature will be increased and precipitation pattern will be altered, thereby influencing soil moisture content, physiological plant processes and crop development in agricultural areas, with impacts on crop yield and the chemical composition of seeds. Warming and drought often occur simultaneously. The combination of multiple abiotic stresses can be synergistic, leading to additive negative effects on crop productivity. To date, little information is available from multi-factor experiments analyzing interactive effects of warming and reduced precipitation in an arable field. In addition, one major issue of studying climate change effects on crop development in the long-term is that weather conditions can vary strongly between years, e.g., with hot and dry summers in comparison to cool and wet ones, which directly affects soil moisture content and indirectly affects crop development. Thus, considering yearly weather conditions seems to be important for the analyses of climate change effects on aboveground biomass and harvestable yield of crops. The aim of the present work was to identify single and combined effects of soil warming (+2.5 °C), reduced summer precipitation amount (-25%), and precipitation frequency (-50%) on crop development, ecophysiology, aboveground biomass and yield as well as on yield quality of wheat, barley, and oilseed rape grown in the Hohenheim Climate Change (HoCC) field experiment. This thesis presents novel results from the HoCC experiment in the long-term perspective. Thus, aboveground biomass and yield data (2009-2018) of the three crops were analyzed with regard to their inter-annual variability, including annual fluctuations in weather conditions.This thesis consists of three publications. In the first and second publication a field experiment within the scope of the HoCC experiment was conducted with spring barley (Hordeum vulgare L. cv. RGT Planet) and winter oilseed rape (Brassica napus L. cv. Mercedes) in 2016 and 2017. The objective was to investigate the impacts of soil warming, altered precipitation pattern and their interactions on biomass production and crop yield. In addition, it was examined, whether the simulated climate changes affecting barley photosynthesis and the seed quality compounds of oilseed rape. In the third publication, long-term plant productivity data of wheat, barley, and oilseed rape were evaluated, including aboveground biomass and yield data from the field experiment in 2018 with winter wheat (Triticum aestivum L. cv. Rebell).
Influence of land use on abundance, function and spatial distribution of N-cycling microorganisms in grassland soils
(2015) Keil, Daniel; Kandeler, Ellen
This thesis focuses on the influence of land use on the abundance, function and spatial distribution of N-cycling microorganisms in grassland soils, but also on soil biogeochemical properties, as well as on enzyme activities involved in the carbon-, nitrogen-, and phosphorous cycle. The objective of this thesis was tackled in three studies. All study sites that were investigated as part of this thesis were preselected and assigned according to study region and land use within the framework of the “Exploratories for Functional Biodiversity Research – The Biodiversity Exploratories” of the Deutsche Forschungsgemeinschaft priority program 1374. The first study addressed the question whether land-use intensity influences soil biogeochemical properties, as well as the abundance and spatial distributions of ammonia-oxidizing and denitrifying microorganisms in grasslands of the Schwäbische Alb. To this end, a geostatistical approach on replicated grassland sites (10 m × 10 m), belonging to either unfertilized pastures (n = 3) or fertilized mown meadows (n = 3), representing low and high land-use intensity, was applied. Results of this study revealed that land-use intensity changed spatial patterns of both soil biogeochemical properties and N-cycling microorganisms at the plot scale. For soil biogeochemical properties, spatial heterogeneity decreased with higher land-use intensity, but increased for ammonia oxidizers and nirS-type denitrifiers. This suggests that other factors, both biotic and abiotic than those measured, are driving the spatial distribution of these microorganisms at the plot scale. Furterhmore, the geostatistical analysis indicated spatial coexistence for ammonia oxidizers (amoA ammonia-oxidizing archaea and amoA ammonia-oxidizing bacteria) and nitrate reducers (napA and narG), but niche partitioning between nirK- and nirS-type denitrifiers. The second study aimed at whether land-use intensity contributes to spatial variation in microbial abundance and function in grassland ecosystems of the Schwäbische Alb assigned to either low (unfertilized pastures, n = 3), intermediate (fertilized mown pastures, n = 3), or high (fertilized mown meadows, n = 3) land-use intensity. Plot-scale (10 m × 10 m) spatial heterogeneity and autocorrelation of soil biogeochemical properties, microbial biomass and enzymes involved in C, N, and P cycle were investigated using a geostatistical approach. Geostatistics revealed spatial autocorrelations (p-Range) of chemical soil properties within the maximum sampling distance of the investigated plots, while greater variations of p-Ranges of soil microbiological properties indicated spatial heterogeneity at multiple scales. An expected decrease in small-scale spatial heterogeneity in high land-use intensity could not be confirmed for microbiological soil properties. Finding smaller spatial autocorrelations for most of the investigated properties indicated increased habitat heterogeneity at smaller scales under high land-use intensity. In the third study, the effects of warming and drought on the abundance of denitrifier marker genes, the potential denitrification activity and the N2O emission potential from grassland ecosystems located in the Schwäbische Alb, the Hainich, and the Schorfheide region were investigated. Land use was defined individually for each grassland site by a land-use index that integrated mowing, grazing and fertilization at the sites over the last three years before sampling of the soil. It was tested if the microbial community response to warming and drought depended on more static site properties (soil organic carbon, water holding capacity, pH) in interaction with land use, the study region and the climate change treatment. It was further tested to which extent the N2O emission potential was influenced by more dynamic properties, e.g. the actual water content, the availability of organic carbon and nitrate, or the size of the denitrifier community. Warming effects in enhanced the potential denitrification of denitrifying microorganisms. While differences among the study regions were mainly related to soil chemical and physical properties, the land-use index was a stronger driver for potential denitrification, and grasslands with higher land use also had greater potentials for N2O emissions. The total bacterial community did not respond to experimental treatments, displaying resilience to minor and short-term effects of climate change. In contrast, the denitrifier community tended to be influenced by the experimental treatments and particularly the nosZ abundance was influenced by drought. The results indicate that warming and drought affected the denitrifying communities and the potential denitrification, but these effects are overruled by study region and site-specific land-use index. This thesis gives novel insights into the performance of N-cycling microorganisms in grassland ecosystems. The spatial distribution of soil biogeochemical properties is strongly dependent on land-use intensity, as in return is the spatial distribution of nitrifying and denitrifying microorganisms and the ecosystem services they perform. Yet, future work will be necessary to fully understand the interrelating factors and seasonal variability, which influence the ecosystem functioning and ecosystem services that are provided by N-cycling soil microorganisms at multiple scales.
Radial tree growth dynamics and xylem anatomy along an elevational gradient in the El Sira Mountains, Peru
(2019) Niessner, Armin; Küppers, Manfred
The explicit purpose of this study was to (1) characterize climate and vegetation along the western slope of the Cerros del Sira (Peru), (2) evaluate radial tree growth along this slope in response to seasonal rainfall anomalies, (3) reveal how the meteorological environment controls tree radial stem growth, and (4) to investigate how xylem anatomy relates to dynamics of tree growth. From May 2011 until September 2015, radial stem growth of 67 trees was monitored using point-dendrometers, and meteorological parameters were measured within five sites along an elevational gradient. Additionally, tree dimensions (stem diameter, stem height) and xylem anatomical traits (mean vessel diameter, vessel frequency, cumulative vessel area and potential hydraulic conductivity) were determined. The transect extends from lowland terra firme forests (ca. 250 m asl) over submontane forests, late and mid successional montane cloud forests up to exposed elfin forests (ca. 2200 m asl). Continuous rainfall records for remote tropical areas are extremely rare and measurements along this transect are also incomplete. Monthly rainfall estimates by the TRMM PR satellite ("product 3B42") were highly correlated with rain gauge observations, although they underestimate rainfall at high elevations. Different intra-annual tree growth patterns could be identified within each elevational forest type, showing species/individuals with seasonally independent continuous or alternating growth patterns and strictly seasonal growth. Stem growth at each site was typically higher during rainy seasons, except for in the elfin forest. The rainy season from October 2013 to March 2014 was extraordinarily dry, with only 73 % of long-term mean precipitation received, which resulted in reduced tree radial growth rates, again with the exception of the elfin forest. Different analytical approaches revealed that precipitation is the main growth-controlling factor at lower elevations, especially during rainy seasons. Growth within montane and cloud forests positively correlates to solar radiation. Tree growth within the elfin forest is only weakly correlated to meteorological parameters, but dry conditions during dry seasons promote growth. It was hypothesized that (1) individuals/species with large vessel diameters and low vessel frequencies have higher radial growth rates, but are more vulnerable to relatively dry periods. Therefore, (2) they are more likely to grow seasonally and predominantly during rainy seasons, (3) their growth during the exceptionally dry rainy season 2013/14 was more constrained, and (4) their growth is generally closer correlated to meteorological parameters. Larger trees tend to have larger vessel diameters, which positively relates to radial growth rates, and they also tend to grow more seasonal. As hypothesized, trees having large vessel diameters are more sensitive to droughts, as indicated by stronger positive correlations with rainfall and negative with solar radiation. However, in mountainous forests, relations between xylem anatomical traits and tree growth dynamics seem to be more complex. In late-successional cloud forests, growth of trees with large vessel diameter is positively, while of trees with small vessel diameter negatively related to solar radiation. Sensitivity to the dry rainy season 2013/14, expressed as relative reduction in growth compared to "normal" rainy seasons, could not be explained by xylem anatomical traits, contradicting the preceded hypothesis. Tropical lowland rainforest species, especially individuals with large vessels, will likely suffer from increasing drought frequencies and intensities. How montane forest ecosystems will react to a (globally) changing climate is rather uncertain, especially in exposed elfin forests. Results of this study suggest that species of late-successional tropical montane forests may profit from higher temperatures. While montane tropical rain forests may also suffer from prolonged droughts, exposed ridges covered by elfin forests still receive plenty of precipitation and may benefit from receiving more solar radiation for photosynthesis and, thus, grow faster.
Reducing uncertainty in prediction of climate change impacts on crop production in Ethiopia
(2024) Rettie, Fasil Mequanint; Streck, Thilo
Ethiopia, with an economy heavily reliant on agriculture, is among the countries most vulnerable to climate change. It faces recurrent climate extreme events that result in devastating impacts and acute food shortages for millions of people. Studies that focus on their influence on agriculture, especially crop productivity, are of particular importance. However, only a few studies have been conducted in Ethiopia, and existing studies are spatially limited and show considerable spatial invariance in predicted impacts, as well as discrepancies in the sign and direction of impacts. Therefore, a robust, regionally focused, and multi-model assessment of climate change impacts is urgently needed. To guide policymaking and adaptation strategies, it is essential to quantify the impacts of climate change and distinguish the different sources of uncertainty. Against this backdrop, this study consisted of several key components. Using a multi-crop model ensemble, we began with a local climate change impact assessment on maize and wheat growth and yield across three sites in Ethiopia . We quantified the contributions of different sources of uncertainty in crop yield prediction. Our results projected a of 36 to 40% reduction in wheat grain yield by 2050, while the impact on maize was modest. A significant part of the uncertainty in the projected impact was attributed to differences in the crop growth models. Importantly, our study identified crop growth model-associated uncertainty as larger than the rest of the model components. Second, we produced a high-resolution daily projections database for rainfall and temperature to serve the requirement for impact modeling at regional and local levels using a statistical downscaling technique based on state-of-the-art GCMs under a range of emission scenarios called Shared Socioeconomic Pathways (SSPs). The evaluated results suggest that the downscaling strategy significantly reduced the biases between the GCM outputs and the observation data and minimized the errors in the projections. Third, we explored the magnitude and spatial patterns of trends in observed and projected changes in climate extremes indices based on downscaled high-resolution daily climate data to serve as a baseline for future national or regional-level impact assessment. Our results show largely significant and spatially consistent trends in temperature-derived extreme indices, while precipitation-related extreme indices are heterogeneous in terms of spatial distribution, magnitude, and statistical significance coverage. The projected changes in temperature-related indices are dominated by the uncertainties in the GCMs, followed by uncertainties in the SSPs. Unlike the temperature-related indices, the uncertainty from internal climate variability constitutes a considerable proportion of the total uncertainty in the projected trends. Fourth, we examined the regional-scale impact of climate change on maize and wheat yields by crop modeling, in which we calibrated and validated three process-based crop models to guide the design of national-level adaptation strategies in Ethiopia. Our analysis showed that under a high-emissions scenario, the national-level median wheat yield is expected to decrease by 4%, while maize yield is expected to increase by 2.5% by the end of the century. The CO2 fertilization effect on the crop simulations would offset the projected negative impact. Crop model spread followed by GCMs was identified as the largest contributor to overall uncertainty to the estimated yield changes. In summary, our study quantifies the impact of climate change and demonstrates the importance of a multi-model ensemble approach. We highlight the significant impacts of climate change on wheat yield in Ethiopia and the importance of crop model improvements to reduce overall uncertainty in the projected impact.
Regionalising a soil-plant model ensemble to simulate future yields under changing climatic conditions
(2023) Bendel, Daniela Silke; Streck, Thilo
Models are supportive in depicting complex processes and in predicting their effects. Climate models are applied in many areas to assess the possible consequences of climate change. Even though Global Climate Models (GCM) have now been regionalised to the national level, their resolution of down to 5x5 km2 is still rather coarse from the perspective of a plant modeller. Plant models were developed for the field scale and work spatially explicitly. This requires to make adjustments if they are applied at coarser scales. The regionalisation of plant models is reasonable and advantageous against the background of climate change and policy advice, both gaining in importance. The higher the spatial and temporal heterogeneity of a region, the greater the computational need. The (dis)aggregation of data, frequently available in differing resolutions or quality, is often unavoidable and fraught with high uncertainties. In this dissertation, we regionalised a spatially-explicit crop model ensemble to improve yield projections for winter wheat under a changing climate. This involved upscaling a crop model ensemble consisting of three crop models to the Stuttgart region, which has an area of 3,654 km2. After a thorough parameter estimation performed with a varying number of Agricultural Response Units on a high-performance computing cluster, yield projections up to the year 2100 were computed. The representative concentration pathways of the Intergovernmental Panel on Climate Change (IPCC) RCP2.6 (large reduction of CO2 emissions) and RCP8.5 (worst case scenario) served as a framework for this effort. Under both IPCC scenarios, the model ensemble predicts stable winter wheat yields up to 2100, with a moderate decrease of 5 dt/ha for RCP2.6 and a small increase of 1 dt/ha for RCP8.5. The variability within the model ensemble is particularly high for RCP8.5. Results were obtained without accounting for a potential progress in wheat breeding.
Simulating the impact of land use change and climate change on the supply of ecosystem services in a rubber-dominated watershed in Southwestern China
(2020) Thellmann, Kevin; Asch, Folkard
This cumulative PhD thesis investigates the expansion of rubber (Hevea brasiliensis Müll. Arg.) plantations and the ensuing multiple impacts on biodiversity and the supply of ecosystem services (ESS) in a mountainous watershed in Xishuangbanna Prefecture, Southwestern China. In recent decades, the study area, the Nabanhe Reserve, saw the expansion of rubber plantations and the loss of extensive forest areas, which led to a substantial decline in ESS. Workshops with regional stakeholders resulted in the development of three future land use scenarios for Nabanhe Reserve (2015 – 2040), varying in their degree of rubber expansions, management options and reforestations efforts. In the first study, the InVEST (Integrated Valuation of Ecosystem Services and Trade-offs) modeling framework was used to analyze the impact of these rubber expansion scenarios on selected ESS: sediment retention, water yield, habitat quality, and carbon sequestration. In addition, a model for assessing potential rubber yields was developed and implemented in ArcGIS. The analysis also included different statistical weighting methods to include rankings for the preference of ESS from three contrasting stakeholder groups (prefecture administration, tourists, off-site citizens). The study concludes that the integrated ESS indices would be overestimated without the inclusion of the stakeholder groups. The second study introduced a new method to identify potential tipping points in the supply of ESS. Here, time-series data derived from InVEST have been combined with a sequential, data-driven algorithm (R-method) to identify potential tipping points in the supply of ESS within two contrasting scenarios of rubber expansion in Nabanhe Reserve. The tipping point analysis included hydrological, agronomical, and climate-regulation ESS, as well as multiple facets of biodiversity. The model results showed regime shifts indicating potential tipping points, which were linked to abrupt changes in rubber yields, in both scenarios and at varying spatial scales. The study concludes that sophisticated land use planning may provide benefits in the supply of ESS at watershed scale, but that potential trade-offs at sub-watershed scales should not be neglected. The third study focused on modeling hydrological ESS (water yield and sediment export) in Nabanhe Reserve under multiple scenarios of land use and climate change in order to assess how both drivers influence the supply of these ESS. Three rubber expansion scenarios were analyzed in combination with multiple climate change scenarios using the InVEST modeling framework. Simulation results showed that the effect of land use and land management decisions on water yield in Nabanhe Reserve are relatively minor (4% difference in water yield between land use scenarios), when compared to the effects that future climate change will exert on water yield (up to 15% increase or 13% decrease in water yield compared to the baseline climate). Changes in sediment export were more sensitive to land use change (15% increase or 64% decrease) in comparison to the effects of climate change (up to 10% increase). The study concludes that in the future, particularly dry years may have a more pronounced effect on the water balance in Nabanhe Reserve as the higher potential evapotranspiration increases the probability for periods of water scarcity, especially in the dry season. In conclusion, the studies showed detrimental consequences induced by rubber expansions for all assessed ESS, with the exception of rubber yields. Further continuing the trend of rubber expansions in the study area is not the best option in terms of integrated ESS supply on a landscape scale. Land use planning alternatives, such as rubber expansions restricted to suitable areas only, in combination with reforestation efforts at less suitable locations, may be used to keep crucial environmental functions intact. Policy regulations at the local level, if properly assessed with spatial models and integrated stakeholder feedback, have the potential to buffer the typical trade-off between agricultural intensification and environmental protection. The implementation of these regulations might still pose a considerable challenge. The methods introduced in this Dissertation can easily be transferred to regions facing comparable land use situations, as InVEST and a large amount of the utilized spatial datasets are freely available.
The genetic basis of heat tolerance in temperate maize (Zea mays L.)
(2016) Frey, Felix P.; Stich, Benjamin
The global mean temperature and probability of heat waves are expected to increase in the future, which has the potential to cause severe damages to maize production. To elucidate the genetic mechanisms of the response of temperate maize to heat stress and for the tolerance to heat stress, in a first experiment I applied gene expression profiling. Therewith, I investigated the transcriptomic response of temperate maize to linearly increasing heat levels. Further, I identified genes associated with heat tolerance in a set of eight genotypes with contrasting heat tolerance behavior. I identified 607 heat responsive genes, which elucidate the genetic pathways behind the response of maize to heat stress and can help to expand the knowledge of plant responses to other abiotic stresses. Further, I identified 39 genes which were differentially regulated between heat tolerant and heat susceptible inbreds and, thus, are putative heat tolerance candidate genes. Two of these candidate genes were located in genome regions which were associated with heat tolerance during seedling and adult stage that have been detected in QTL studies in the frame of this thesis. Their exact molecular functions, however, are still unknown. The statistical approach to identify heat tolerance genes, presented in my thesis, enables researchers to investigate the transcriptomic response of multiple genotypes to changing conditions across several experiments, considering their natural variation for a quantitative trait. In order to develop more heat tolerant cultivars, knowledge of natural variation for heat tolerance in temperate maize is indispensable. Therefore, heat tolerance was assessed in a set of intra- and interpool Dent and Flint populations on a multi-environment level. Usually, heat stress in temperate Europe occurs during the adult stage of maize. However, as maize is of increasing importance as a biogas crop, farmers can reduce the growth period by postponed sowing after the harvest of the winter cereals in early summer and, thus, sensitive maize seedlings can be exposed to heat stress. Therefore, I aimed to assess heat tolerance in six connected segregating Dent and Flint populations during both developmental stages considering besides multiple environments also multiple traits. At heat stress, I observed an average decrease of 20% of the shoot dry weight during seedling stage and an average of 50% of yield loss, when heat stress was present during adult stage. At the heat locations heat stress was present in the year, when the experiments were conducted as temperatures exceeded 32°C there for more than 400 hours during the growing period in contrast to less than 30 hours at the standard locations. This emphasizes that maize crop production can suffer with the increasing number and intensity of summer heat waves. Furthermore, the study revealed strong differences between genotypes, which was indispensable to differentiate between heat tolerant and heat susceptible inbred lines. The tested genotypes originating from the Flint pool turned out to possess higher heat tolerance during seedling stage, whereas the genotypes derived from the Dent pool possessed higher heat tolerance during adult stage. This fact could be exploited by the maintenance of two pools with contrasting heat tolerance and could be beneficial for hybrid breeding. A direct selection of more heat tolerant genotypes in terms of grain yield is expensive and time-consuming. To facilitate the selection process in order to develop more heat tolerant cultivars, breeders could make use of marker assisted selection. To lay the foundation for this technique, in my thesis, QTL for heat tolerance during adult and during seedling stage were identified with the previously mentioned populations. Two QTL explained 19% of the total variance for heat tolerance with respect to grain yield in a simultaneous fit. Furthermore each two QTL were identified for two principal components, which accounted for heat tolerance during seedling stage. They explained 14 and 12% of the respective variance. The results can be used by breeding companies to develop marker assays in order to select heat tolerant genotypes from their proprietary genetic material during both stages in an initial screening. This would reduce the field capacities considerably, which are needed to test heat tolerance on a field level.
The impacts of conflict and climate change on food security and nutrition in Chad
(2023) Bachofer, Robert Paul; Sousa-Poza, Alfonso
This dissertation aims at providing an overview of how armed conflict and climate impact food security and nutrition in the African country of Chad. It analyzes the impacts of the Boko Haram insurgency on food security and nutrition, and those of annually recurrent droughts on households’ coping strategies. Placing the Republic of Chad in the context of the administrative regions of surrounding countries, where Boko Haram and its splinter groups operated at the time of their greatest territorial expansion (Extreme Nord in Cameroon, Lac in Chad, and Diffa in Niger, as well as the Nigerian states of Borno, Yobe, and Adamawa), it covers the timeframe from late 2009 to 2016. On the qualitative side, a systematic literature review on the impacts of Boko Haram on food security and related concepts in the study area, a review of conflict databases and press coverage of Boko Haram’s activities, and semi-structured interviews of Chadian security experts help to locate where and when the insurgency was active, the violence it perpetrated, and the impacts it had. On the quantitative side, the thesis leverages DHS data of 1997 and 2010, MICS data of 2000 and 2015 for childhood malnutrition indicators. The 2011, 2013, 2014, 2015 and 2016 ENSA waves are used for household food security indicators. Across the broader Lake Chad region, Boko Haram activity led to the displacement of food producers, interruption of migration routes of pastoralists, increased exposure to cattle rustling, and transport restrictions affecting food markets. It is also associated with changes in trade routes and border closures leading to price fluctuations, market closure and decrease in market activity, reduction in smallholder farmers’ income, and curbing physical access of consumers to food markets due to the destruction of infrastructure and security concerns. These factors contributed to increases in wasting, stunting, and child mortality rates, decreases in school enrolment and years of schooling, and limitations in access to health care. On the macroeconomic level, agricultural output, GDP, and other development indicators have been affected negatively. However, on the micro level, many studies focus on the insurgency’s impacts on displacement, in the form of refugees and IDPs within specific camps. These populations struggle with their loss of agro-pastoralist livelihoods, and with limited access to land and water to sustain them. Coupled with low employment rates, this results in low income across camps. However, whether this results in lack of food availability and diversity differs significantly from camp to camp, and access to health, education, and other basic service is highly unequally distributed as well. Concerningly, trading food for sex is a practice in at least some camps. Centering in on Chad itself, the thesis exploits the fact that Boko Haram perpetrated only criminal but not political violence between 2010 and 2014. During this period, insurgents plundered and pillaged Chadian villages in the seasonal wetlands of Lake Chad, and committed other criminal acts, but did not engage Chadian security forces for political gains; hence, this setup allows to isolate the impacts that terrorist organizations can achieve through purely criminal violence. Applying a DID approach, the dissertation finds that such criminal violence causes deteriorations in the z-scores of underweight and wasting of children under the age of five years by -0.085 points and -0.305 points, respectively. It finds that the insurgency’s criminal violence causes a decrease of 31.7 percentage points in the participation of households in agricultural activities and a decrease of their dietary diversity by 53.7 points. These impacts are large, especially considering that criminal violence perpetrated by Boko Haram in Chad received little to no international attention. The impacts of seasonal drought on food security, however, are much more measured. Out of five coping strategies assessed, seasonal drought has impacts to a statistically significant degree on only two: The prevalence of households selling non-productive assets and the prevalence of using their savings increases by 7.1 percentage points and 7.6 percentage points, respectively, when drought exposure increases by 1 percentage point on a low administrative level. Estimates of heterogeneous treatment effects and other robustness tests support a causal interpretation of these coefficients, which are obtained through two-way fixed effect estimations. These findings do not mean that drought-affected households do not enact other coping strategies, too. It merely means that seasonal drought likely causes them to use only two very specific coping strategies, but it does not cause the use of others.