Sondersammlungen

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Comparative ungulate diversity and biomass change with human use and drought: implications for community stability and protected area prioritization in African savannas
(2025) Bartzke, Gundula S.; Ogutu, Joseph O.; Piepho, Hans‐Peter; Bedelian, Claire; Rainy, Michael E.; Kruska, Russel L.; Worden, Jeffrey S.; Kimani, Kamau; McCartney, Michael J.; Ng'ang'a, Leah; Kinoti, Jeniffer; Njuguna, Evanson C.; Wilson, Cathleen J.; Lamprey, Richard; Hobbs, Nicholas Thompson; Reid, Robin S.; Bartzke, Gundula S.; Biostatistics Unit, Faculty of Agricultural Sciences, Institute of Crop Science, University of Hohenheim, Stuttgart, Baden‐Württemberg, Germany; Ogutu, Joseph O.; Biostatistics Unit, Faculty of Agricultural Sciences, Institute of Crop Science, University of Hohenheim, Stuttgart, Baden‐Württemberg, Germany; Piepho, Hans‐Peter; Biostatistics Unit, Faculty of Agricultural Sciences, Institute of Crop Science, University of Hohenheim, Stuttgart, Baden‐Württemberg, Germany; Bedelian, Claire; Danish Institute for International Studies, Copenhagen, Capital Region of Denmark, Denmark; Rainy, Michael E.; International Livestock Research Institute, Nairobi, Nairobi County, Kenya; Kruska, Russel L.; International Livestock Research Institute, Nairobi, Nairobi County, Kenya; Worden, Jeffrey S.; World Wildlife Fund, Nairobi, Nairobi County, Kenya; Kimani, Kamau; International Livestock Research Institute, Nairobi, Nairobi County, Kenya; McCartney, Michael J.; Campfire Conservation, Nairobi, Nairobi County, Kenya; Ng'ang'a, Leah; International Livestock Research Institute, Nairobi, Nairobi County, Kenya; Kinoti, Jeniffer; Department of Infrastructure, Lands and Urban Development, County Government of Laikipia, Rumuruti, Laikipia, Kenya; Njuguna, Evanson C.; International Livestock Research Institute, Nairobi, Nairobi County, Kenya; Wilson, Cathleen J.; International Livestock Research Institute, Nairobi, Nairobi County, Kenya; Lamprey, Richard; Department of Natural Resources, Faculty of Geo‐Information Science and Earth Observation, University of Twente, Enschede, Overste, the Netherlands; Hobbs, Nicholas Thompson; Natural Resource Ecology Laboratory, Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, Colorado, USA; Reid, Robin S.; International Livestock Research Institute, Nairobi, Nairobi County, Kenya
Drought and human use may alter ungulate diversity and biomass in contrasting ways. In African savannas, resource‐dependent grazers such as wildebeest (Connochaetes taurinus) and zebra (Equus quagga) may decline or disperse as resources decline, opening space for more drought‐tolerant species such as gazelles (Eudorcas and Nanger) and impala (Aepyceros melampus). This shift can increase species richness, evenness, and overall ungulate diversity. Although higher diversity may stabilize ungulate communities, it may be associated with lower biomass (the total body mass of all individuals in a community), which in turn affects vegetation structure and composition, nutrient cycling, energy flows, and other organisms in savannas. While ungulate biomass often declines during drought or in areas of intense human use, the effects on diversity changes under low‐to‐moderate human use remain less clear. Our fine‐scale censuses in the Maasai Mara National Reserve and adjacent pastoral lands in Kenya showed that ungulate biomass declined more than diversity in the 1999 drought year. In the normal rainfall year of 2002, diversity peaked along the reserve boundary, but species richness leveled off in the drought year. Biomass peaked in the reserve in both census years, and migratory ungulates moved further into the reserve in the drought year, where diversity declined. These findings suggest that core protected areas are crucial for maintaining ungulate biomass, while transition zones from protected and pastoral lands support higher diversity unless drought reduces species richness.
Connecting resonance theory with social-ecological thinking: Conceptualizing self-world relationships in the context of sustainability transformations
(2025) Brossette, Florian; Bieling, Claudia
Relationships and interactions between humans and their environment play an important role in sustainability transformations. However, their conceptualization remains a big challenge in current social-ecological research. We propose resonance theory by the German sociologist Hartmut Rosa as a fruitful framework to advance social-ecological thinking. Resonance theory investigates the quality of the relationships between self and world and scrutinizes their relevance for transformations. To illustrate the potentials of resonance theory, we use a vignette approach to cases of landscape stewardship initiatives in the Black Forest Biosphere Reserve in Germany. In distinguishing between self and world and highlighting the role of relationships, resonance theory brings ontological and epistemological clarity, while overcoming a strict dichotomy between social and ecological. We find that resonance theory provides a much needed framework to describe how system-wide transformations emerge from interactions and out of relationships at the individual level. We argue that resonance theory contributes to social-ecological systems thinking by adding the notion of uncontrollability in transformations and shifting the debate on agency towards relationships. Synthesis and applications: This paper demonstrates the meaningfulness of relational paradigms for real-world transformations in theory and practice.
Effect of liquefaction temperature and enzymatic treatment on bioethanol production from mixed waste baked products
(2025) Almuhammad, Mervat; Kölling, Ralf; Einfalt, Daniel; Almuhammad, Mervat; Yeast Genetics and Fermentation Technology, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstraße 23, 70599, Stuttgart, Germany; Kölling, Ralf; Yeast Genetics and Fermentation Technology, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstraße 23, 70599, Stuttgart, Germany; Einfalt, Daniel; Botanical Garden, Ulm University, Hans-Krebs-Weg, 89081, Ulm, Germany
This study investigates the effect of different liquefaction temperatures (50–70 °C) and four commercial enzyme formulations on glucose release and subsequent ethanol yield, using mixed waste baked products as a substrate. Among the enzymes tested, Amylase GA 500 proved to be superior in the hydrolysis of starch at lower temperatures (50 °C and 55°C). At higher liquefaction temperatures (65 °C and 70°C) all four enzyme preparations showed comparable activity. The highest glucose concentration (205.7 g/L) and the highest ethanol yield (92 g/L) were achieved with Amylase GA 500 at 65 °C. Its superior performance is attributed to the synergistic activity of α-amylase and glucoamylase, which facilitates efficient starch hydrolysis. Crucially, we discovered that the liquefaction temperature profoundly affects fermentation speed independently of the initial glucose concentration or the enzyme preparation used for starch hydrolysis. This novel mechanistic insight suggests that higher temperature treatment either makes an additional factor crucial for yeast fermentation available or depletes/destroys an inhibitor present in the complex waste bakery product matrix. These findings highlight the critical role of temperature and enzyme formulation in optimizing bioethanol production from bakery waste, supporting the development of more sustainable and efficient waste-to-biofuel processes.
From import to establishment? Experimental evidence for seasonal outdoor survival of two Rhipicephalus species in Germany
(2025) Fachet-Lehmann, Katrin; Lindau, Alexander; Mackenstedt, Ute
The brown dog tick (Rhipicephalus sanguineus s.l.), though not endemic in Germany, is regularly introduced via travelers with dogs and imported rescue dogs. Due to its relevance in veterinary and human medicine, its potential to establish in Germany’s climate is of interest. Although previous studies confirm indoor survival and reproduction of R. sanguineus s.s. in Germany, climate change and milder winters may also allow outdoor survival. This study assessed the survival of R. sanguineus s.s. and R. innaei from February 2023 to May 2024 using laboratory-bred ticks placed at indoor and outdoor sites. Tick survival (adults, nymphs, larvae) was monitored weekly, along with temperature and humidity. Reproductive success was evaluated via oviposition and larval hatching. R. sanguineus s.s. adults survived up to 44 weeks, nymphs up to 20 weeks, and larvae up to 5 weeks. R. innaei showed shorter survival (37, 10, and 4 weeks, respectively). Successful oviposition and larval hatching occurred outdoors between May´23 and September´23 for both species. However, winter survival was not observed; all ticks died following sub-zero temperatures in December´23. Despite the inability to overwinter outdoors, both species can survive for extended periods in spring and summer and may enter homes via dogs, where conditions favor year-round survival. Their ability to transition indoors via dogs, where conditions favor year-round survival, suggests a potential for establishment in Germany through combined indoor and seasonal outdoor persistence.
Microbial inoculants modulate the rhizosphere microbiome, alleviate plant stress responses, and enhance maize growth at field scale
(2025) Francioli, Davide; Kampouris, Ioannis D.; Kuhl-Nagel, Theresa; Babin, Doreen; Sommermann, Loreen; Behr, Jan H.; Chowdhury, Soumitra Paul; Zrenner, Rita; Moradtalab, Narges; Schloter, Michael; Geistlinger, Joerg; Ludewig, Uwe; Neumann, Günter; Smalla, Kornelia; Grosch, Rita
Background: Field inoculation of crops with beneficial microbes is a promising sustainable strategy to enhance plant fitness and nutrient acquisition. However, effectiveness can vary due to environmental factors, microbial competition, and methodological challenges, while their precise modes of action remain uncertain. This underscores the need for further research to optimize inoculation strategies for consistent agricultural benefits. Results: Using a comprehensive, multidisciplinary approach, we investigate the effects of a consortium of beneficial microbes (BMc) ( Pseudomonas sp. RU47, Bacillus atrophaeus ABi03, Trichoderma harzianum OMG16) on maize ( Zea mays cv. Benedictio) through an inoculation experiment conducted within a long-term field trial across intensive and extensive farming practices. Additionally, an unexpected early drought stress emerged as a climatic variable, offering further insight into the effectiveness of the microbial consortium. Our findings demonstrate that BMc root inoculation primarily enhanced plant growth and fitness, particularly by increasing iron uptake, which is crucial for drought adaptation. Inoculated maize plants show improved shoot growth and fitness compared to non-inoculated plants, regardless of farming practices. Specifically, BMc modulate plant hormonal balance, enhance the detoxification of reactive oxygen species, and increase root exudation of iron-chelating metabolites. Amplicon sequencing reveals shifts in rhizosphere bacterial and fungal communities mediated by the consortium. Metagenomic shotgun sequencing indicates enrichment of genes related to antimicrobial lipopeptides and siderophores. Conclusions: Our findings highlight the multifaceted benefits of BMc inoculation on plant fitness, significantly influencing metabolism, stress responses, and the rhizosphere microbiome. These improvements are crucial for advancing sustainable agricultural practices by enhancing plant resilience and productivity.
Should we delay leaf water potential measurements after excision? Dehydration or equilibration?
(2024) Perera‐Castro, Alicia V.; Puértolas, Jaime; Fernández-Marín, Beatriz; González-Rodríguez, Águeda M.; Perera-Castro, Alicia V.; Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna (ULL), 38200, La Laguna, Canary Islands, Spain; Puértolas, Jaime; Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna (ULL), 38200, La Laguna, Canary Islands, Spain; Fernández-Marín, Beatriz; Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna (ULL), 38200, La Laguna, Canary Islands, Spain; González-Rodríguez, Águeda M.; Department of Botany, Ecology and Plant Physiology, Universidad de La Laguna (ULL), 38200, La Laguna, Canary Islands, Spain
Background: Accurate leaf water potential (Ψw) determination is crucial in studying plant responses to water deficit. After excision, water potential decreases, even under low evaporative demand conditions, which has been recently attributed to the equilibration of pre-excision Ψw gradients across the leaf. We assessed the influence of potential re-equilibration on water potential determination by monitoring leaf Ψw and relative water content decline after excision using different storage methods. Results: Even though leaf Ψw declined during storage under low evaporative demand conditions, this was strongly reduced when covering the leaf with a hydrophobic layer (vaseline) and explained by changes in relative water content. However, residual water loss was variable between species, possibly related to morpho-physiological leaf traits. Provided water loss was minimized during storage, pre-excision leaf transpiration rate did not affect to the magnitude of leaf Ψw decline after excision, confirming that transpiration-driven Ψw gradients have no effect on leaf Ψw determination. Conclusions: Disequilibrium in water potentials across a transpiring leaf upon excision is dissipated very quickly, well within the elapsed time between excision and pressurization, therefore, not resulting in overestimation of leaf Ψw measured immediately after excision. When leaf storage is required, the effectiveness of a storage under low evaporative demand varied among species. Covering with a hydrophobic layer is an acceptable alternative.
Spatiotemporal climatic signals in cereal yield variability and trends in Ethiopia
(2025) Abera, Kidist; Gayler, Sebastian; Piepho, Hans‑Peter; Streck, Thilo; Abera, Kidist; Institute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, Stuttgart, Germany; Gayler, Sebastian; Institute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, Stuttgart, Germany; Piepho, Hans‑Peter; Biostatistics Unit, Institute of Crop Science, University of Hohenheim, Stuttgart, Germany; Streck, Thilo; Institute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, Stuttgart, Germany
Climatic variability and recurrent drought can strongly affect the variability of crop yield and are therefore frequently considered a risk to food security in Ethiopia. A better understanding of how crop yields vary in space and time, and their relationship to climatic and other driving factors, can assist in enhancing agricultural production and adapting to and mitigating the impacts of climate change. We applied a multiple linear regression model to examine the spatiotemporal climatic signal (air temperature, precipitation, and solar radiation) in the yields of the most important crops (maize, sorghum, tef, and wheat) over the period 1995–2018. An analysis of the climatic data indicated that growing season temperature increased significantly in most regions, but the trends in precipitation were not significant. The yields of maize, sorghum, tef, and wheat tended to increase across most crop-growing areas, particularly in the west, but was highly variable. The results highlight large spatial differences in the contribution of climatic trends to crop-yield variability across Ethiopian regions. The trends in climatic variability did not significantly affect crop yields in some areas, whereas in the main crop-growing areas, up to − 39.2% of yield variability could be attributed to the climatic trends. Specifically, the climatic trends negatively affected maize yields but positively affected sorghum, tef, and wheat yields. Nationally, the average impacts of climatic trends on crop yields was relatively small, ranging from a 3.2% decrease for maize to a 0.7% increase for wheat. In contrast, technological advancements contributed substantially more to yield gains, with annual increases ranging from 4.3% for wheat to 5.1% for sorghum. These findings highlight the dominant role of non-climatic drivers, particularly improved agricultural technology, in shaping crop yield trends. Our findings underscore the spatial heterogeneity of climate impacts on agriculture and highlight the critical importance of technological progress in enhancing crop productivity. They also provide actionable insights for designing crop- and location-specific adaptation strategies, and stress the need for integrated, climate-resilient development pathways in the region.
Sulfate enhances metabolic acclimation under drought stress - a comparative study of grapevine and maize
(2025) Lehr, Patrick Pascal; Erban, Alexander; Kopka, Joachim; Zörb, Christian
The importance of sulfate fertilization in plant production has becoming increasingly relevant due to the decline in atmospheric sulfur inputs. Moreover, high-intensity cropping systems are increasingly facing drought scenarios. The role of stomata is crucial during drought stress and is linked to sulfate metabolism. This study investigates the impact of sulfate application on the drought response of grapevine and maize guard cells. Both plant species may serve as crop model for analysing underlying physiological processes in a low fertilizer demanding crop such as grapevine and a high fertilizer demanding crop such as maize. Increased sulfate concentration in leaves was triggered by drought in maize and grapevine, but in grapevine only when additional sulfate was applied. Additional sulfate application improved sulfur availability under drought conditions, which enhanced drought stress response in grapevine and maize. This was characterized by enhanced metabolic acclimation under drought conditions. The effect of sulfate on the drought stress response was markedly diminished in guard cells, indicating enhanced metabolic stability of guard cells against external influences. These results underscore the significance of adequate sulfate supply to crops for optimal drought stress response and suggest that sulfate fertilisation may serve as a potential option to enhance drought acclimation
The tale of two Ions Na⁺ and Cl⁻: unraveling onion plant responses to varying salt treatments
(2024) Romo-Pérez, Maria Luisa; Weinert, C. H.; Egert, B.; Kulling, S. E.; Zörb, Christian; Romo-Pérez, M. L.; University of Hohenheim, Institute of Crop Science, Quality of Plant Products 340e, Schloss Westflügel, 70599, Stuttgart, Germany; Weinert, C. H.; Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut, Haid-und-Neu-Straße 9, 76131, Karlsruhe, Germany; Egert, B.; Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut, Haid-und-Neu-Straße 9, 76131, Karlsruhe, Germany; Kulling, S. E.; Department of Safety and Quality of Fruit and Vegetables, Max Rubner-Institut, Haid-und-Neu-Straße 9, 76131, Karlsruhe, Germany; Zörb, C.; University of Hohenheim, Institute of Crop Science, Quality of Plant Products 340e, Schloss Westflügel, 70599, Stuttgart, Germany
Background: Exploring the adaptive responses of onions ( Allium cepa L.) to salinity reveals a critical challenge for this salt-sensitive crop. While previous studies have concentrated on the effects of sodium (Na⁺), this research highlights the substantial yet less-explored impact of chloride (Cl⁻) accumulation. Two onion varieties were subjected to treatments with different sodium and chloride containing salts to observe early metabolic responses without causing toxicity. Results: The initial effects of salinity on onions showed increased concentrations of both ions, with Cl⁻ having a more pronounced impact on metabolic profiles than Na⁺. Onions initially adapt to salinity by first altering their organic acid concentrations, which are critical for essential functions such as energy production and stress response. The landrace Birnförmige exhibited more effective regulation of its Na⁺/K⁺ balance and a milder response to Cl⁻ compared to the hybrid Hytech. Metabolic alterations were analyzed using advanced techniques, revealing specific responses in leaves and bulbs to Cl⁻ accumulation, with significant changes observed in organic acids involved in the TCA cycle, such as fumaric acid, and succinic acid, in both varieties. Additionally, there was a variety-specific increase in ethanolamine in Birnförmige and lysine in Hytech in response to Cl⁻ accumulation. Conclusion: This comprehensive study offers new insights into onion ion regulation and stress adaptation during the initial stages of salinity exposure, emphasizing the importance of considering both Na⁺ and Cl⁻ when assessing plant responses to salinity.

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