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Im Kontext der Problematik von Fehlinformationen in der populärwissenschaftlichen Literatur widmet sich diese Arbeit in einer Fallstudie drei häufig verkauften Büchern Peter Wohllebens. Untersucht wird, wie nah diese Werke sich am aktuellen Stand der Forschung orientieren und wie gut die getätigten Aussagen nachvollziehbar sind. Für die Untersuchung wurde der Inhalt der Bücher codiert und die resultierenden 8899 Codiereinheiten quantitativ und qualitativ-vergleichend analysiert. Ergänzt wurde dies durch die qualitativ-vergleichende Analyse von drei Schwerpunktthemen. Aus den Ergebnissen wird geschlussfolgert, dass Wohllebens Nähe zum wissenschaftlichen Diskurs unter Einschränkungen ausreichend und die Nachvollziehbarkeit seiner Aussagen mangelhaft ist. Basierend auf diesen Erkenntnissen werden mögliche Maßnahmen und Handlungsfelder für eine Erhöhung der wissenschaftlichen Qualität populärwissenschaftlicher Werke diskutiert. Es werden weitere potentielle Forschungsmöglichkeiten für ein besseres Verständnis der Situation in den Populärwissenschaften identifiziert und vorgeschlagen.
Urban areas are prone to climate change impacts. Simultaneously the world’s population increasingly resides in cities. In this light, there is a growing need to equip urban decision makers with evidence-based climate information tailored to their specific context, to adequately adapt to and prepare for future climate change.
To construct climate information high-resolution regional climate models and their projections are pivotal, to provide a better understanding of the unique urban climate and its evolution under climate change. There is a need to move beyond commonly investigated variables, such as temperature and precipitation, to cover a wider breath of possible climate impacts. In this light, the research presented in this thesis is centered around enhancing the understanding about regional-to-local climate change in Berlin and its surroundings, with a focus on humidity. More specifically, following a regional climate modelling and data analysis approach, this research aims to understand the potential of regional climate models, and the possible added value of convection-permitting simulations, to support the development of high-quality climate information for urban regions, to support knowledge-based decision-making.
The first part of the thesis investigates what can already be understood with available regional climate model simulations about future climate change in Berlin and its surroundings, particularly with respect to humidity and related variables. Ten EURO-CORDEX model combinations are analyzed, for the RCP8.5 emission scenario during the time period 1970 ̶ 2100, for the Berlin region. The results are the first to show an urban-rural humidity contrast under a changing climate, simulated by the EURO-CORDEX ensemble, of around 6 % relative humidity, and a robust enlarging urban drying effect, of approximately 2 ̶ 4 % relative humidity, in Berlin compared to its surroundings throughout the 21st century.
The second part explores how crossing spatial scales from 12.5 km to 3 km model grid size affects unprecedented humidity extremes and related variables under future climate conditions for Berlin and its surroundings. Based on the unique HAPPI regional climate model dataset, two unprecedented humidity extremes are identified happening under 1.5 °C and 2 °C global mean warming, respectively SH>0.02 kg/kg and RH<30 %. Employing a double-nesting approach, specifically designed for this study, the two humidity extremes are downscaled to the 12.5 km grid resolution with the regional climate model REMO, and thereafter to the 3 km with the convection-permitting model version of REMO (REMO NH). The findings indicate that the convection-permitting scale mitigates the SH>0.02 kg/kg moist extreme and intensifies the RH<30 % dry extreme. The multi-variate process analysis shows that the more profound urban drying effect on the convection-permitting resolution is mainly due to better resolving the physical processes related to the land surface scheme and land-atmosphere interactions on the 3 km compared to the 12.5 km grid resolution. The results demonstrate the added value of the convection-permitting resolution to simulate future humidity extremes in the urban-rural context.
The third part of the research investigates the added value of convection-permitting models to simulate humidity related meteorological conditions driving specific climate change impacts, for the Berlin region. Three novel humidity related impact cases are defined for this research: influenza spread and survival; ragweed pollen dispersion; and in-door mold growth. Simulations by the regional climate model REMO are analyzed for the near future (2041 ̶ 2050) under emission scenario RCP8.5, on the 12.5 km and 3 km grid resolution. The findings show that the change signal reverses on the convection-permitting resolution for the impact cases pollen, and mold (positive and negative). For influenza, the convection-permitting resolution intensifies the decrease of influenza days under climate change. Longer periods of consecutive influenza and mold days are projected under near-term climate change. The results show the potential of convection-permitting simulations to generate improved information about climate change impacts in urban regions to support decision makers.
Generally, all results show an urban drying effect in Berlin compared to its surroundings for relative and specific humidity under climate change, respectively for the urban-rural contrast throughout the 21st century, for the downscaled future extreme conditions, and for the three humidity related impact cases. Added value for the convection-permitting resolution is found to simulate humidity extremes and the meteorological conditions driving the three impacts cases.
The research makes novel contributions that advance science, through demonstrating the potential of regional climate models, and especially the added value of convection-permitting models, to understand urban rural humidity contrasts under climate change, supporting the development of knowledge-based climate information for urban regions.
The worldwide decline of plant and insect species during the last decades has far-reaching consequences for the functionality of ecosystems and their inherent processes. Pollination as one of them is an indispensable ecosystem service for human wellbeing. More than 85% of the worldwide flowering-plant species depend to some degree on pollination by insects (pollinators). Similarly, many pollinators depend on the flowers of the plants, as they need nectar and pollen as food resources for themselves and their offspring. However, an increasing number of pollinator and plant species are threatened by multiple, interacting, and sometimes synergistic causes (habitat loss, fragmentation, diseases, parasites, pesticides, monocultures) that are becoming a growing threat to ecosystem functioning. Given the loss of plant species diversity, it is increasingly difficult for pollinators to find food throughout the year. Therefore, this study analyses the influence of plant diversity on pollinators. The study was conducted in the course of the Jena Experiment, which is a long-term biodiversity experiment (since 2002) with 60 plant species, common to Central European Arrhenatherum grasslands. With a plant diversity gradient of 1, 2, 4, 8, 16, and 60 plant species per plot, time-series data resulted from a wide range of ecosystem processes, ranging from productivity, decomposition, C-storage, and N-storage to herbivory, and pollination. These were studied to investigate the mechanisms underlying the relationships between biodiversity and ecosystem processes.
Chapter 2 studies the spatio-temporal distribution of pollinators on flowers along an experimental plant diversity gradient. For this purpose, the pollinators were divided into four different functional groups, i.e. honeybees, bumblebees, solitary bees and hoverflies. In particular, the spatial pollinator behaviour was examined, that is, in which flowering height the flowers were visited within the plant community. In order to study the temporal component, pollinator visits were observed over the course of the day and the season. As a result, an unprecedented high resolution of plant-pollinator interactions was found. For the first time it was possible to demonstrate that the different pollinator functional groups can complementarily use different spatio-temporal niches which was most pronounced in species-rich plant mixtures,. This leads to the conclusion that species-rich plant mixtures provide sufficient resources that can be used by generalists, such as honeybees and bumblebees, as well as other pollinator functional groups, such as hoverflies and solitary bees.
Chapters 3 and 4 continues on the chemical composition of flower nectar (nectar) of various plant species. Nectar is used as food resource for adult pollinators, but is also largely used as a supply for their offspring, making it the most important pollinator reward. The chemical composition of the nectar was analysed for the two most important macronutrients, carbohydrates (C) and amino acids (AA), using high performance liquid chromatography (HPLC). Subsequently, their contents were analysed in terms of concentration, proportional content and the ratio of carbohydrates to amino acids (C:AA).
In Chapter 3, the nectar of 34 plant species from the grasslands of the Jena Experiment was compared. In doing so, similarities and/or differences of the nectar compositions were investigated with respect to the most important macronutrients carbohydrates and amino acids between the individual species but also between the most representative plant families. This should lead to a better understanding about how plant diversity influences consuming pollinators and which factors, e.g. phylogenetics, morphology or ecology, can lead to different nectar compositions. We could show that each plant species differs in terms of carbohydrate content, amino acid content and C:AA-ratio. In addition, there were clear differences between the four representative plant families Apiaceae, Asteraceae, Fabaceae and Lamiaceae regarding the proportions of essential amino acids. The proportions of the individual sugars and the C:AA-ratios also differed greatly between the four plant families. Therefore, it can be assumed that these nectar contents are family-specific. The need for differences in carbohydrate content are probably due to the different morphology of the flowers, as plants with open flowers and exposed nectar, as in Apiaceae and Asteraceae, can protect their nectar from evaporation if the nectar has a higher osmolality, which can be achieved by a higher hexose (fructose and glucose) content. Thus, the nectar can remain dilute for a longer time and consequently remain consumable for pollinators, which in turn can contribute to the pollination of plants. Fabaceae and Lamiaceae showed different results. Here the nectar was probably protected from evaporation by closed flowers, which explains the high proportion of sucrose, leading to a lower osmolality that would enhance evaporation for exposed nectar. The metabolic pathways controlling the family-specific C:AA-ratios are yet to be explored. In conclusion, it can be suggested that this study contributes to elucidating the morphological and phylogenetic characteristics that control each plant species’ nectar composition.
In Chapter 4, nectar was investigated in the context of diversity effects on the example of the plant species Field Scabious, Knautia arvensis. It was analysed to what extent the nectar quality (nutrient content) differs between plant individuals of one species. The underlying factors causing these differences in nectar composition have never been studied before. In order to investigate these coherences, plant communities in the Jena Experiment of different plant species richness levels containing the target plant species K. arvensis were used. In particular, we examined whether the nectar of K. arvensis is influenced by other neighbouring plant species, e.g. through competition for pollinators. The carbohydrate and amino acid content in nectar varied both between individuals of K. arvensis and between the different plant species richness levels. However, there were significant non-linear differences in the proportions of certain essential and phagostimulatory amino acids, which were produced proportionally more in the nectar of K. arvensis plants in species-rich plant communities, while histidine, one of the generally inhibiting amino acids tended to be less present. Our findings therefore suggest that the nectar of K. arvensis is more palatable when the plants grow in species-rich plant communities.
Overall, these studies indicate how fragile plant-pollinator interactions are but also how important plant species-rich grasslands are to support plant-pollinator interactions. Increased plant species diversity is essential to ensure the availability of flowering resources throughout the year. Pollinators, such as honeybees, bumblebees, solitary bees, and hoverflies can use the niches in time and in vertical space complementarily. However, in plant species-poor grasslands there may be more niche overlaps, which is probably due to a reduced availability of resources. This points to the need to include different plant species belonging to different plant families, whose nectar may have evolved in response to morphological flower traits and metabolic pathways. Therefore plant species diversity can supply pollinators with nectar differing in carbohydrate and amino acid content and thus differing in quality. Also C-AA ratios have proven to be a useful measurement to reveal differences between plant species. In addition, C:AA ratios were not differing in nectar of K. arvensis individuals growing in different plant species richness levels, although their nectar seemed to be more attractive in mixtures with 16 plant species, likely due to higher content of essential and phagostimulatory amino acids than in plant species-poor mixtures. Thus further research investigating diversified farming systems, including pollinator-friendly practices to reveal the attractiveness of different plant species. More diversified field margins and grasslands, for the maintenance of pollinator services for sustainable provision of crop pollination.
Rangelands are the most widespread land-use systems in drylands, where they often represent the only sustainable form of land-use due to the limited water availability. The intensity of the land-use of such rangeland ecosystems in drylands depends to a large extent on the climatic variability in time and space, as on the one hand it influences the growth of biomass and therefore the grazing intensity, but on the other hand it can also destroy entire herds through extreme climatic events. Rangeland systems are seriously threatened by climate change, because climate change will alternate the availability of water in time and space. This is dangerous in that we have not yet fully understood how grazing affects vegetation under different climatic conditions. Inadequate rangeland management can quickly lead to serious degradation of the grazing grounds. This dissertation therefore deals with the question which role climatic variability plays for the effects of grazing on vegetation in dry rangelands. The relatively intact steppes in central Mongolia were chosen as a model system. They are characterised by low precipitation and high climatic variability in the south (100 mm annual precipitation), and comparatively high precipitation and low climatic variability in the north (250 mm). The effects of grazing on vegetation on 15 grazing transects were investigated along the climatic gradient. The central elements were the plant species and their abundances on 10 m x 10 m areas, for which functional characteristics such as height, affiliation of functional groups or leaf nutrients were recorded. The main hypothesis of this dissertation is that grazing has a greater impact on vegetation communities with increasing rainfall. To test this hypothesis, three studies were carried out. In a first study, we found that the vegetation communities in the dry area differ strongly along the climatic gradient, while the plant communities in the wetter area differ more strongly along the grazing gradient. The results of the second study suggested that this difference can be explained by a functional environmental filter that becomes weaker from south to north as the niche spectrum increases. The third study has shown that this is likely a function of the higher availability of resources, which at the same time leads to higher grazing pressure, therewith stressing the vegetation especially in years with droughts. In summary, I conclude that the climate gradient also represents an environmental filter that filters species for certain characteristics, thus having a significant influence on the vegetation. Climatic variability influences the effect of grazing on vegetation, which is particularly problematic where the grazing intensity is high and the species are less adapted to strong climatic fluctuations. Future scenarios predict increasing productivity and therefore increasing livestock density. This may lead to an increase in floristic and functional diversity across the climate gradient, but also to increasing grazing effects and therefore threads for overgrazing. Increasing climatic variability is likely to intensify this thread, especially in the moister regions, whereas the dry rangelands are likely to be more resilient due to the adaptation of the plants to non-equilibrium dynamics. The fate of Mongolia’s rangeland systems therefore clearly lies in the hand of the rangeland managers. The sustainable use of Mongolia’s vast steppe ecosystems might depend on a flexible livestock management system which balances the grazing intensity with the available resources, while still considering climatic variability as a key for the management decisions. A potential link-up for future studies might arise from the shortcomings of the studies presented. This dissertation suggests that long-term observations are necessary to better understand the effects of climatic variability. In addition, grazing gradients must be selected more carefully in the future in order to be able to ensure better comparability, and functional analyses should have a stronger relationship to forage quality. With these points in mind, a comparative study of several rangeland ecosystems on a global level must be the ultimate goal. This could be an important step for the sustainable use of drylands in the context of global climate and land use change.
Globalization with its increasing emergence of global value chains is one of the main driving forces behind persisting unsustainable production and consumption patterns. The global coffee market provides a fitting example, as it is connected to many sustainability issues like the persisting poverty of coffee farmers, and degrading ecosystems. Many interventions, from state-led regulation to industry-led certification processes, exist, that try to change global value chains to shift societies back on more sustainable trajectories. However, due to the complexity and manifold connections between social and ecological factors, global value chains pose a wicked problem. To this date, it is still under debate if these interventions are an effective means to change global value chains. With climate change and persisting issues of social justice as strong accelerators, calls are increasingly made for a radical transformation of global production and consumption patterns. Many frameworks try to inform research and real-world policies for a transformation of global value chains. In this dissertation, I use the framework of the practical, political and personal sphere proposed by O’Brien and Sygna (2013). The authors highlight that the interactions between these three spheres bare the greatest potential for a transformation towards sustainability. however, in this dissertation, I argue that it is exactly at the nexus between the three spheres of transformation where barriers towards a fundamental shift of systems occur. I, therefore, use three perspectives to bring empirical nuance to the problems that arise on the interplay between the different spheres of transformation. These perspectives are: (1) the scientific perspective: using a systematic review of alternative trade arrangements; (2) the producer perspective: facilitating a participatory network analysis of social-ecological challenges of Ugandan coffee farmers and their adaptive management practices; (3) the consumer perspective: through the use of a German consumer survey and a structural equation model to investigate into the Knowledge-Doing-Gap end-consumers are facing. These three perspectives bring empirical nuance to the interplay between the different spheres as they highlight the real-world barriers that arise within and at the nexus of the three spheres. Through the results from the scientific perspective, I am able to show that most of the research is investigating the certified market and that the effectiveness of labels rarely exceeding the practical sphere. My empirical research on the producer perspective highlights that Ugandan coffee farmers facilitate a variety of on-farm crop management (practical sphere) but their support structures rarely exceed informal exchange with neighboring communities (political sphere). Exchange with governmental actors and global traders is happening but has been assessed as not sufficient to cope with the social-ecological challenges the producers are facing. Through the results of the consumer perspective, I am able to highlight that even though end-consumers have pro-sustainable attitudes (personal sphere) they are facing situational constraints (political sphere) that create a gap between their attitudes and the respective behavior. Using these empirical insights about drivers and barriers for a transformation I propose that frameworks, aiming to inform research and policies, need to include two aspects: (1) the notion of a forced transformation as one of the major influencing factors for a deliberative transformation; and (2) the translational capacity of the frameworks to create meaningful interdisciplinary discourses in different contexts. I, therefore, propose two approaches that should function as a starting point for further development of transformation frameworks (1) a fourth sphere, called the “planetary force” to include the notion of a forced transformation that is already happening in different contexts, highlighted by the producer perspective in this dissertation; and (2) the consequent use of methods that create interdisciplinary exchange and rigorous testing.
Assessment of forest functionality and the effectiveness of forest management and certification
(2021)
Forest ecosystems are complex systems that develop inherent structures and processes relevant for their functioning and the provisioning of ecosystem services that contribute to human wellbeing. So far, forest management focused on timber production while other services were less rewarded. With increasing climate change impacts, especially regulating ecosystem services such as microclimate regulation are ever more relevant to maintain forest functions and services. A key question is how forest management supports or undermines the ecosystems’ capacity to maintain those functions and services. Forest management implies silvicultural interventions such as thinning and timber harvesting and ranges from single tree extraction to large clearcuts as well as forest reserves without active forest operations and shape the character of forest ecosystems (e.g. natural versus planted forests). Artificial plantings, monocultures and management for economic timber production simplify forest structures and impair ecosystem resilience, resistance and the existence of forests but also the services essential for the prosperity and health of humanity. Efforts to reduce the negative impacts and attempts to safeguard forest functions are manifold and include compulsory national and international guidelines and regulations for forest management, conventions, but also voluntary mechanisms such as certification systems.
The main objective of this thesis was the development of a concept to assess the functionality of forests and to evaluate the effectiveness of forest ecosystem management including certification. An ecosystem-based and participatory methodology, named ECOSEFFECT, was developed. The method comprises a theoretical and an empirical plausibility analysis. It was applied to the Russian National FSC Standard in the Arkhangelsk Region of the Russian Federation – where boreal forests are exploited to meet Europe's demand for timber. In addition, the influence of forestry interventions on temperature regulation in Scots pine and European beech forests in Germany was assessed during two extreme hot and dry years in 2018 and 2019.
Microclimate regulation is a suitable proxy for forest functionality and can be applied easily to evaluate the effectiveness of forest management in safeguarding regulating forest functions relevant under climate change. Microclimate represents the most decisive factor differentiating clearcuts and primary forests. Thus, the assessment of forest microclimate regulation serves as convenient tool to illustrate forest functionality. In the boreal and temperate forests studied in the frame of this thesis, timber harvesting reduced the capacity to self-regulate forests’ microclimate and thus impair a crucial part of ecosystem functionality. Changes in structural forest characteristics influenced by forest management and silviculture significantly affect microclimatic conditions and therefore forest ecosystems’ vulnerability to climate change. Canopy coverage and the number of cut trees were most relevant for cooling maximum summer temperature in pine and beech forests in northern Germany. Maximum temperature measured at ground level increased by 0.21 – 0.34 K when 100 trees were cut. Opening the forest canopy by 10 % caused an increase of maximum temperature at ground-level by 0.53 K (including pine and beech stands). Relative temperature cooling capacity decreased with increasing wood harvest activities and dropped below average values when more than 656 trees per hectare (in 2018; and 867 trees in 2019) were felled. In pine stands with a canopy cover below 82 % the relative temperature buffering capacity was lower than the average. Mean maximum temperature measured at ground-level and in 1.3 m was highest in a pine-dominated sample plots with relatively low stand volume (177 m3 ha-1) and 9 K lower in a sample plot with relatively high stock volumes of F. sylvatica (> 565 m3 ha-1). During the hottest day in 2019, the difference in temperature peaks was more than 13 K for pine-dominated sample plots with relatively dense (72 %) and low (46 %) canopy cover.
The Russian FSC standard has the potential to improve forest management and ecological outcomes, but there are shortcomings in the precision of targeting actual problems and ecological commitment. In theory, FSC would transform forest management practices and induce positive changes and effective outcomes by addressing 75 % of the identified contributing factors including highly relevant factors and threats including large-scale (temporary) tree cover loss, which contributes to reducing about half of the identified stresses in the ecosystem. It is theoretically plausible that FSC prevents logging in high conservation value forests and intact forest landscapes, reduces the size and number of clearcuts, and prevents hydrological changes in the landscape. However, the standard was not sufficiently explicit and compulsory to generate a strong and positive influence on the identified problems and their drivers. Moreover, spatial data revealed, that the typical regular clearcut patterns of conventional timber harvesting continue to progress into the FSC-certified boreal forests, also if declared as ‘Intact Forest Landscape’. This results in the need to verify the assumptions and postulates on the ground as it remains unclear and questionable if functions and services of boreal forests are maintained when FSC-certified clearcutting continues. On the clearcuts, maximum temperature exceeded 36 °C and stayed below 30 °C in the closed primary forest. The number of days with temperatures above 25 °C at least doubled on clearcuts. Temperature cooling capacity was reduced by up to 14 % and temperature buffering capacity up to 60 %. The main reason why FSC-certified clearcuts do not differ from conventional clearcuts is that about 97 % of trees within equally large clearcut sites of up to 50 ha were removed. The spatial design of clearcuts, their size and the intensity of clearing as well as the density of skidding trails for timber extraction was not positively influenced by FSC-certification. Annual tree cover loss was lowest in non-certified areas. This means, that FSC may even contribute to an increased biomass removal within the clearcuts, which compromises the ecosystems’ capacity to recover and maintain ecological functions and services. The analysis of satellite-based data on tree cover loss showed that clearcutting causes secondary dieback in the surrounding of the cleared area. FSC-certification does not prevent the various negative impacts of clearcutting and thus fails to safeguard ecosystem functions. The postulated success in reducing identified environmental threats and stresses, e. g. through a smaller size of clearcuts, could not be verified on site. The empirical assessment does not support the hypothesis of effective improvements in the ecosystem. In practice, FSC-certification did not contribute to change clearcutting practices sufficiently to effectively improve the ecological performance. Sustainability standards that are unable to translate principles into effective outcomes fail in meeting the intended objectives of safeguarding ecosystem functioning. Clearcuts that carry sustainability labels are ecologically problematic and ineffective for the intended purpose of ecological sustainability.
The overexploitation of provisioning services, i.e. timber extraction, diminishes the ecosystems’ capacity to maintain other services of global significance. It also impairs ecosystem functions relevant to cope with and adapt to other stresses and disturbances that are rapidly increasing under climate change.
Forest management under climate change needs to apply precautionary principles and reduce further ecological risks such as secondary dieback and deterioration of regulating services that are relevant for the functioning of forests. Forest managers have to avoid ecological disimprovements by applying strict ecological principles with effective outcomes in order to maintain functional forests that regulate their own microclimate also as a basis for sustainable economic benefits.
Global environmental changes and the subsequent biodiversity loss has raised concerns over the consequences for the functioning of ecosystems and human well-being. This thesis provides new mechanistic insights into the role of tree diversity in regulating forest productivity and forests’ responses to climate change. The thesis also addresses the overlooked functional role of ecological continuity in mediating ecosystem processes in the context of multiple global environmental changes. The findings of the thesis emphasize the need to retain the functional integrity of forest ecosystem by preserving biodiversity and acknowledging the ecological memory forests.
"Sustainable development: enough for everyone, forever" is the definition of sustainability. Sustainable landscape development is the main goal of decision makers worldwide. Achieving this goal in the long term leads to achieving social, economic and environmental sustainability. Remote sensing has been playing an essential role in monitoring remote areas. This study has employed part of the role of remote sensing in supporting the direction of decision makers towards sustainable landscape development. The study has focused on some of the main elements affecting sustainable environment as stated in Agenda 21. These elements are land uses, specifically agricultural land uses, water quality, forests, and water hazards such as floods.
Three research programs were undertaken to investigate the role of Terrasar-x imagery, as a source of remote sensing data, in monitoring the environment and achieving the previous stated elements. The investigation was intended to investigate the effectiveness of TSX imagery in identifying the cropping pattern of selected study areas by employing a pixel-based supervised maximum likelihood classifier, as published in Paper I, assessment of the efficiency of using TSX imagery in determining land use and the flood risk maps by applying an object-based decision tree classifier as published in Paper II, and determination of the potential of inferential statistics tests such as the two samples Z-test and multivariate analysis, for example Factor Analysis, for identifying the kind of forest canopy, based on the backscattering coefficient of TSX imagery of forest plots, as presented in Paper III. Papers I and II covered two pilot areas in the Lower Saxonian Elbe Valley Biosphere Reserve “das Biosphärenreservat „Niedersächsische Elbtalaue„ around Walmsburger Werder between Elbe-Kilometer 533 - 543 and Wehninger Werder between Elbe-Kilometer 505 - 520. Paper III focused on the Fuhrberger Feld water protection area near Hanover in Germany. The inputs for this research were mainly SAR Imagery and the ground truth data collected from field surveys, in addition to databases, geo-databases and maps.
The study presented in Paper I used two filters to decrease speckle noise namely De-Grandi as multi-temporal speckle filter, and Lee as an adaptive filter. A multi-temporal classification method was used to identify the different crops using a pixel-based maximum likelihood classifier. The classification accuracy was assessed based on the external user accuracy for each crop, the external producer accuracy for each crop, the Kappa index and the external total accuracy for the entire classification. Three cropping pattern maps were produced namely the cropping pattern map of Wehninger Werder in 2011 and the cropping pattern maps of Walmsburger Werder in 2010 and in 2011. The study showed that image filtering was essential for enhancing the accuracy of crop classification. The multi-temporal filter De-Grandi enhanced the producer accuracy by about 10% compared to the Lee filter. Furthermore, gathering and utilizing large ground truth data greatly enhanced the accuracy of the classification. The research verified that using sequence images covering the growing season usually improved the classification results. The results exposed the effect of the polarization, where using VV-polarized data enabled on average 5% higher classification accuracy than the HH-polarized data, however using dual polarized data enhanced the classification accuracy by 3%. The study demonstrated that the majority of the classifications produced according to the crop calendar had higher total producer accuracy than using all acquisitions.
The study demonstrated undertaken in Paper II applied the decision tree object-based classifier in determining the major land uses and the inundation extent areas in 2011 and 2013 using the Lee-filtered imagery. Based on the maps produced for the land uses and inundation areas, the hazard areas due to the floods in 2011 and 2013 were identified. The study illustrated that 95% of the inundated area was classified correctly, that 90% of vegetated lands were accurately determined, and around 80% of the forest and the residential areas were correctly recognized. The study demonstrated that the residential areas did not experience any hazards in both pilot areas, however some cultivated lands were fully or partially submerged in 2011. These fields are in the high flood zone and therefore are expected to be entirely submerged during future high floods. Although, these fields were flooded in January 2011, they were cultivated with maize and potatoes in summer 2011 and in subsequent years and consequently were inundated in June 2013 with high economic losses to the owners of these fields.
The research undertaken in Paper III statistically analyzed the backscattering coefficient of the Lee-filtered TSX in some forest plots by the Factor Analysis and two sample Z-test. The study showed that Factor analysis tools succeeded in differentiating between the coniferous forest and the deciduous forest and mixed forest, but failed to discriminate between the deciduous and the mixed forest. On one hand, only one factor was extracted for each sample plot of the coniferous forest with approximately equal loadings during the whole acquisition period from March 2008 to January 2009. On the other hand, two factors were extracted for each deciduous or mixed forest sample plot, where one factor had high loadings during the leaf-on period from May to October, and the other one had high loadings during the leaf-off period from November to April. Furthermore, the research revealed that the two sample Z-test enabled not only differentiation between the deciduous and the mixed forest against the coniferous forest, but also discrimination between deciduous forest and the mixed forest. Statistically significant differences were observed between the mean backscatter values of the HH-polarized acquisitions for the deciduous forest and the mixed forest during the leaf-off period, but no statistically significant difference was found during the leaf-on period. Moreover, plot samples for the deciduous forest had slightly higher mean backscattering coefficients than those for the mixed forest during the leaf-off period.
Der Klimawandel gehört zu den globalen Herausforderungen des 21. Jahrhunderts. Die Folgen des Klimawandels machen sich u.a. in Form von Hitze, Stürmen oder Starkregen bemerkbar. Dem Klimawandel kann sowohl mithilfe des Klimaschutzes (Mitigation) in Form der Ursachenbekämpfung als auch mithilfe der Klimaanpassung (Adaption), welche sich in Form von Anpassungsmaßnahmen an das sich ändernde Klima darstellt, begegnet werden. Aufgrund ihrer Struktur sind insbesondere urbane Strukturen von Klimafolgen betroffen. Der Raum- und Umweltplanung komme dabei hinsichtlich der sozial-ökologischen Naturverhältnisse eine wichtige Rolle zu, sofern sie die Aufgaben der Krisenbewältigung annehmen und verantwortungsvoll wahrnehmen will.
Auch die Hansestadt Lüneburg steht zukünftig vor einigen Herausforderungen. Durch den allgemeinen Trend der Urbanisierung und als Teil der Metropolregion Hamburg gilt Lüneburg als beliebter Wohnraum. Folglich werden auch zukünftig neue Baugebiete erschlossen, Wohnraum geschaffen und Verdichtung sowie Flächenversiegelung vorgenommen. Im aktuell bearbeiteten Klimagutachten für Lüneburg werden bereits bisherige Risikogebiete bezüglich Hitze und Frischluft aufgezeigt.
In der vorliegenden Arbeit werden zunächst die der Ausarbeitung zugrungegelegten Begriffe sowie die Bedeutung von Starkregenereignissen in der Stadtplanung definiert und näher erläutert. Darauf folgt die Darstellung der zur Beantwortung der Forschungsfrage verwendeten Methoden. Anschließend werden in der empirischen Forschung das bisherige Auftreten von Starkregen analysiert, bestehende Adaptionsstrategien norddeutscher Städte und Regionen aufgezeigt, ein Zukunftsausblick auf Grundlage wissenschaftlicher Prognosen gegeben und konkrete, auf die Hansestadt Lüneburg bezogene, Analysen und Szenarien erstellt, bevor ein Resümee der empirischen Forschung gezogen werden kann. Abschließend wird das methodische Vorgehen reflektiert, die Ergebnisse diskutiert und ein kurzer Ausblick auf zukünftige Herausforderungen gegeben.
Tropical forests worldwide support high biodiversity and contribute to the sustenance of local people’s livelihoods. However, the conservation and sustainability of these forests are threatened by land-use changes and a rapidly increasing human population. In this dissertation, I focused on the effects of land-use change on forest biodiversity in the rural landscapes of southwestern Ethiopia, against a backdrop of human population growth. These landscapes are being progressively degraded, encroached and fragmented as a result of different pressures, including the intensification of coffee production, farmland expansion, urbanization and a growing rural population. Understanding the drivers of biodiversity loss and the responses of biodiversity to such pressures is fundamental to direct conservation efforts in these tropical forests.
This dissertation aimed to characterize biodiversity patterns in the moist Afromontane forests of southwestern Ethiopia and to examine how biodiversity patterns are affected by land-use and land-use changes (mediated by coffee management intensity, landscape attributes and housing development) in a context of a rapidly growing rural population. To achieve this goal, I take an interdisciplinary approach where, first, I examined the effects of coffee management intensity on diversity patterns of woody plants and birds, spanning a gradient of site-level disturbance from nearly undisturbed forest interior to highly managed shade coffee forests. Results showed that specialized species of woody plants (forest specialists) and birds (forest specialists, insectivores and frugivores) were affected by coffee management intensity. The richness of forest specialist trees and the richness and/or abundance of insectivores, frugivores and forest specialist birds decrease with increasing levels of disturbance. Second, I investigated the effects of landscape context on woody plants, birds and mammals. Community composition and specialist species of woody plants and birds were sensitive to landscape context, where woody plants responded positively to gradients of edge-interior and birds to gradients of edge-interior and forest cover. Further results showed that a diverse mammal community, with 26 species, occurs at the forest edge of shade coffee forests and that the leopard, an apex predator in the region depended on large areas of natural forest. A closer examination of leopard activity patterns revealed a shift in the diel activity as a response to human disturbance inside the forest, further highlighting the importance of natural undisturbed forests for leopards in the region. Together, these findings demonstrate the value of low managed shade coffee forests for biodiversity, and importantly, emphasize the irreplaceable value of undisturbed natural forests for biodiversity. Third, I investigated the effects of prospective rural population growth (mediated by housing development) on the forest mammal community. Here, population growth was projected to negatively influence several mammal species, including the leopard. Housing development that encroached the forest entailed worse outcomes for biodiversity than a combination of prioritized development in already developed areas and coffee forest protection. Fourth, to understand the motivations behind high human fertility rates in the region, I examined the determinants of women fertility preferences, including their perceptions on social and biophysical stressors affecting local livelihoods such as food insecurity and environmental degradation. Fertility preferences were influenced by underlying social norms and mindsets, a perceived utilitarian value of children and male dominance within the household, and were only marginally affected by perceptions of social and biophysical stressors. Results further indicated a mismatch between the global discourse on the population-environment-food nexus and local perceptions of this issue by women. My findings suggest the need for new deliberative and culturally sensitive approaches that engage with pervasive social norms to slow down population growth.
Overall, this dissertation demonstrates the key value of moist Afromontane forests in southwestern Ethiopia for biodiversity conservation. It indicates the need to promote coffee management practices that reduce forest degradation and highlights that high priority should be given to the conservation of undisturbed natural forests. It also suggests the need to integrate conservation goals with housing development in landscape planning. A promising approach to achieve the above conservation priorities would be the creation of a Biosphere Reserve and to promote the ecological connectivity between the larger forest remnants in the region. Finally, this dissertation demonstrates the importance of placed-based holistic approaches in conservation that consider both proximate and distal drivers of forest biodiversity decline.
