Fakultät 12 / Institute for Technology and Resources Management in the Tropics and Subtropics
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Onshore wind energy, the highest share of electricity production and the cheapest form of electricity in Germany has become an essential part of Germany’s aim to reach greenhouse gas neutrality in 2045. Still, its development faces social rejection due to perceived health problems that are as a result of wind turbines construction in close proximity to settlements. Forest, the second largest land use in Germany provides consistent wind resources for further expansion of wind energy generation but the social perception about wind energy in the forest is not great as forest is identified as the second largest natural carbon sink and provides some ecological benefits to humans and animals. This thesis sought to provide a quantitative comparison of the climate impact of wind turbines and forests.
Forest carbon stock of German forests was extracted from the German National Forest Inventory (NFI) database on the seven tree species and 2 species classification. The data available were the tree size and tree age. A multiple linear regression was used to estimate the influence of tree age and tree size on the carbon stock on a tree species. The model was performed using R language. The emission saving of Vestas V162-6.0 wind turbine was estimated and the results were compared to those of the results of the multiple linear regression.
It was determined that the emissions payback period of the wind turbine was seven (7) months, and the emissions avoided per year by the wind turbine was equivalent to the carbon stock of about 28 hectares of a matured forest. The research showed that both forest and wind energy are gains to climate change but in different ways and to be able to meet the climate goals, there should be a harmonious use of both resources.
Food insecurity remains a critical issue in Mozambique, where climate variability, socio-economic challenges and over-dependence on staple crops have left many communities vulnerable to malnutrition and poverty. Neglected and Underutilised Crop Species (NUCS), which are adapted to Mozambique's diverse agro-ecological zones and can thrive in marginal environments, hold much potential in addressing both food insecurity issues and improving local agro-biodiversity. Unfortunately, as the name suggests, NUCS remain under-researched and largely disregarded by the general population despite their potential to diversify nutritionally poor diets. This also translates to their value chain which remains mostly underdeveloped. On the other hand side, foods considered as superfoods have found success globally, despite having the same core characteristics as NUCS. Thus, this research aims to learn from global superfoods by identifying success factors along their value chain and leveraging these factors to identify areas of intervention for NUCS in Mozambique, more specifically, using the example of the Spiny Monkey Orange. NUCS hold much potential to strengthen local food security, enhance biodiversity and provide economic opportunities for smallholder farmers. Through the recommendations for policy interventions, suggestions for research priorities and highlighting the need for a multi stakeholder approach, this research aims to increase the visibility of NUCS in Mozambique in order to develop these promising crops in a sustainable and equitable manner.
This research aims at evaluating the use of drone (UAV) imagery in the monitoring of hydromorphological changes in a segment of Erft River in Neuss-Gnadental, which has undergone restoration. In four flight campaigns from February 2022 to November 2023, UAV images were processed with open-source photogrammetry and point clouds processing software (WebODM and CloudCompare) to create 2D orthophotos and 3D point clouds. These products supported delineation of the channel and calculation of geometric properties such as the length, sinuosity, and number of meanders which indicated good correspondence with restoration design objectives and continuous morphological changes like erosion, sediment bars, and woody debris.
Hydromorphological quality at the segment scale was assessed by employing an adapted LAWA protocol using only the 2D orthomosaics and 3D point clouds. Analysis showed that restoration of the river segment produced improvements in characteristics such as flow variety, substrate type, and banks while the near “technical” parts of the segment experienced small alterations. The UAV flights were conducted frequently, enabling documentation of seasonal fluctuations that might not have been observed if the surveys had been carried out using satellite imagery.
Certain advantages included centimetre-resolution imagery, flexibility in flight schedules, and visuals friendly to stakeholder impact. Nevertheless, there were specific workflow challenges. Utilising photogrammetry on open-source tools had high computational costs and required hands-on troubleshooting. Vegetation overshadows complicated semi-automated classification routines and requires manual refinement for reliable channel delineation. However, the approach proved effective for high-resolution, local-to-reach-scale monitoring, strengthening adaptive, data-driven management of river restoration sites.
Subsequent campaigns should include data from multiple sensors (LiDAR, multispectral), the inclusion of classification algorithms, and longer, repeated surveys to evaluate the hydromorphological characteristics under different flow conditions. In summary, UAV imagery enhances hydromorphological monitoring and provides a powerful yet still-developing tool for science-based evaluation of restoration efforts.
This thesis aims to contribute to the development of true cost accounting as a comprehensive approach to assessing the externalities of production systems. The research focuses on understanding the opportunities and limitations of its application, while providing science-based evidence to support advocacy for policies that promote more sustainable food systems. This is achieved through a methodological triangulation approach and a case study in Bolivia which is conducted to compare the impacts of large- and small-scale food systems. The thesis begins with a literature review and is complemented by a series of interviews with Bolivian researchers and international experts, as well as a systematic review of scientific articles and reports on TCA. The results show that while there are opportunities to overcome the limitations faced by the Bolivian researchers, there is a lack of knowledge on limitations experienced by other researchers and the solutions they found to address them. This information would be helpful for researchers and other stakeholders interested in TCA research. More research is needed to improve the tools and methods withing the TCA approach and its consideration in political decision making and development issues.
Assessing and enhancing the cooling potential of urban green infrastructure in Cologne, Germany
(2025)
With the increasing threats of climate change and the associated rise in climate extremes and natural hazards, there has been a growing focus on studies addressing mitigation and adaptation strategies for these hazards, one of which is urban heat islands (UHI). The strategies for mitigating UHI are well-established, with urban green infrastructure being one of the most effective approaches. Previous research has shown that green infrastructure can significantly reduce urban temperatures, although its effectiveness varies depending on specific properties. The cooling effectiveness of these infrastructures differs based on various factors.This paper investigates the cooling potential of various types of green infrastructure, including trees, green roofs, and vertical greenery, in a 16-ha area in Cologne's Volksgarten quarter, based on their biophysical properties. The primary objective was to develop a criteria set for green infrastructure characteristics that enhance cooling potential and climate resilience and to apply this set in assessing the area’s cooling potential. A mixed-methods approach was employed, incorporating literature analysis to define the criteria sets, alongside spatial analysis, in-situ observations, and transpiration modelling to evaluate the study area’s actual cooling potential. The results indicated that, particularly for trees, shading properties based on ecological characteristics such as LAI, height, and crown width play a significant role. For green roofs and vertical greenery, system type characteristics and orientation are potentially more influential. The analysis also included the number of existing infrastructures and based on evaluations of these groups and their locations within the study area, it was possible to identify so-called “cool” and “hot spots” in the study area. The study concludes that while current green infrastructure implementations in the study area have medium cooling potential, there are also clear opportunities for improvement. From these findings, a targeted set of recommendations was drafted to not only enhance cooling potential and climate resistance but also to incorporate additional co-benefits, where specifically for trees, it was possible to make such recommendations even on the species level. This study offers a novel approach to evaluating mitigation strategies, contributing to a deeper understanding of the role of green infrastructure in urban climate resilience, and providing an approach to optimising its benefits with potential implications for urban planners.
Brazil, the largest sugarcane producer and the second-largest bioethanol producer worldwide relies on this product to spearhead its energy transition, strengthen energy security, mitigate the environmental impact of fossil fuels, and drive economic development. Two complementary energy programs—the Brazilian Alcohol Protocol (Proálcool) and the RenovaBio program—drive the expansion of sugarcane-based ethanol production. These programs aim to reduce Brazil’s dependency
on imported oil and integrate biofuels into the energy matrix by promoting ethanol as a renewable fuel alternative.
Despite the benefits, the expansion of sugarcane-based ethanol production poses significant environmental challenges. Effective water management is critical, as the industry heavily relies on water for both crop cultivation and processing. Sugarcane farming is water-intensive, requiring large amounts of water for irrigation, which can stress local water resources. Additionally, vinasse, a nutrient-rich by-product of ethanol production, can be beneficially used for fertigation. However, improper management can lead to nutrient runoff, water pollution, and eutrophication of water bodies.
Proper strategies for vinasse disposal and utilization include controlled application and treatment before disposal to mitigate its environmental impact. Addressing these environmental challenges requires a holistic approach that includes implementing sustainable agricultural practices, advancing technological innovations, and enforcing regulatory
measures. By adopting efficient water use and water circular principles, the sugarcane agroindustry can mitigate its environmental impact and contribute to a more sustainable energy transition and economic development. This research uses field studies and data analysis to assess water use efficiency and vinasse management practices at a sugar and bioethanol plant in Campos dos Goytacazes, Brazil. As the results indicate, the implementation of integrated vinasse management systems could lead to water recovery, estimated to range from 257,405 m3 to 727,490 m3 per year with a unit cost between 0.66 and 3.33 US$ per m3, depending on the system installed. The implementation of these solutions is CAPEX intensive, requiring an initial investment of at least US$ 2.2 million to US$ 8.8 million, corresponding to more than 50% of the total cost of the projects evaluated. Using recycled water in industrial processes and transferring current water withdrawal permits from industrial to agricultural use could increase sugarcane crop yields by up to 79%. This would lead to substantial additional annual revenues to fund the solution. In the best-case scenario, the income-to-cost ratio varies between 6.87 and 25.45, indicating a potential new income from higher ethanol production of up to US$14.7 million per year. The total additional revenue from the implementation of new vinasse management solutions would be beneficial to local agribusiness in water-scarce areas. Improvements in water management practices in ethanol production would make agribusiness more resource-efficient and reduce its environmental impact. This includes reducing the impact caused by vinasse fertigation and decreasing the water footprint of bioethanol production from sugarcane, potentially by up to 34%. Importantly, these water efficiency gains can be achieved without increasing COAGRO's current water withdrawal rates, demonstrating the viability of sustainable water management solutions within the existing operational framework. Furthermore, the research shows that treating vinasse in water-scarce areas can have a positive economic impact, emphasizing the advantages of sustainable water resource management. However, further research into water losses, environmental impacts, and additional infrastructure costs. Assessing how reusing water affects product quality and energy demand is also important. There is potential to improve industrial processes' efficiency and evaluate the impact of enhancements in irrigation and water transport systems.
Agroforestry coffee cultivation represents a promising sustainable agricultural practice in the Cerro de Kuskawás Natural Reserve (CKNR). This study evaluates the impacts of agroforestry systems on the sustainability of smallholder farms, considering economic, environmental, social, and governance dimensions. Data were collected from 15 smallholder farms participating in agroforestry initiatives supported by private sector interventions, specifically through an outgrowers scheme. The research utilized a mixed-method approach, incorporating questionnaires based on the FAO’s TAPE tool and interviews, to assess changes in income stability, biodiversity, gender equity, and land tenure security.
The findings reveal that agroforestry coffee cultivation significantly enhances sustainability across multiple dimensions. Economically, it provides increased income stability and diversification, as smallholders benefit from both the higher market value of sustainably produced coffee and additional revenue from integrated crops like fruits and timber. Environmentally, agroforestry systems improve soil health, enhance biodiversity, and reduce the need for chemical inputs, contributing to a more resilient and sustainable agricultural ecosystem. Socially, the inclusion of women in these agroforestry initiatives has led to improved gender equity and greater empowerment for female smallholders.
However, the study also highlights key challenges, including the high initial costs of transitioning to agroforestry, the dependency on external support from private sector entities, and limited autonomy for smallholders due to centralized control structures. The results suggest that while agroforestry systems have the potential to significantly contribute to sustainable development in the CKNR, achieving long-term sustainability will require addressing these challenges through cooperative models and local governance structures. This study provides valuable insights into the role of agroforestry coffee cultivation in promoting sustainability.
This thesis investigates the sustainability of proposed alternative livelihoods for the mining community of Camargo in the Sierra Gorda of Querétaro, Mexico. With the impending ban on mercury mining under the Minamata Convention, the community faces the urgent need to transition to sustainable livelihoods. Utilizing the Sustainable Livelihoods Framework (SLF) as a guiding theoretical model, this study assesses the current state of the Five Capitals—human, social, natural, physical, and financial—within the community. It also examines the community's perceptions and attitudes toward these alternative livelihoods and evaluates the external influences, such as government and academic institutions, that impact their sustainability.
Data were collected through semi-structured interviews with community members, miners, and external stakeholders, and analyzed using qualitative coding in MAXQDA. The findings reveal a complex interplay between the Capitals of the community and the role that external stakeholders play, highlighting both opportunities and barriers to follow a path of sustainability.
The study concludes that the livelihoods with most potential for a sustainability path are the cultivation of regional species and the installation of a touristic point in the community. A holistic approach that integrates economic, social, and environmental dimensions, while at the same time considers a tailored natural resources management, is essential for ensuring the path of sustainability of the livelihoods. Points of leverage for change are presented for policy and advocacy, infrastructure development of the community, and considering local resource management in the design and implementation of sustainable livelihood strategies.
In recent years, governments worldwide have set out to ensure food security. However, despite the efforts and resources invested, food for all has not been ensured. In the Mexican context, several strategies, programmes and public policies have taken place in the last 30 years; however, the problem has evolved from an issue of lack of food to one of excess caloric intake, promoting chronic diseases such as diabetes and hypertension, a consequence of the generalisation of overweight and obesity in the population. The problem is complex, and action is required from a whole food system perspective, based on public policies that intervene effectively, promoting healthy lifestyles and strengthening the economy and the equitable distribution of wealth. This study focuses on analysing the problem of food insecurity in Mexico from a food systems perspective, as well as analysing public policies from 1982 to 2024, their evolution and changes in approach, as well as their design and coverage in terms of food security and food improvements. The results of this study show that Mexican public policies have not been effective in ensuring food security for all, nor have they been transversal or consistently applied as a long-term project. In conclusion, Mexican public policies must act in a preventive manner, ensure continuity despite changes in government, and take a food system and human rights perspective.
There is an urgent need to develop sustainable agricultural land use schemes. Intensive crop production has induced increased greenhouse gas emissions and enhanced nutrient and pesticide leaching to groundwater and streams. Climate change is also expected to increase drought risk as well as the frequency of extreme precipitation events in many regions. Consequently, sustainable management schemes require sound knowledge of site-specific soil water processes that explicitly take into account the interplay between soil heterogeneities and crops. In this study, we applied a principal component analysis to a set of 64 soil moisture time series from a diversified cropping field featuring seven distinct crops and two weeding management strategies. Results showed that about 97 % of the spatial and temporal variance of the data set was explained by the first five principal components. Meteorological drivers accounted for 72.3 % of the variance and 17.0 % was attributed to different seasonal behaviour of different crops. While the third (4.1 %) and fourth (2.2 %) principal components were interpreted as effects of soil texture and cropping schemes on soil moisture variance, respectively, the effect of soil depth was represented by the fifth component (1.7 %). However, neither topography nor weed control had a significant effect on soil moisture variance. Contrary to common expectations, soil and rooting pattern heterogeneity seemed not to play a major role. Findings of this study highly depend on local conditions. However, we consider the presented approach generally applicable to a large range of site conditions.