Open Access

Traditional farming landscapes typically support exceptional biodiversity. They evolved as tightly coupled social-ecological systems, in which traditional human land-use shaped highly heterogeneous landscapes. However, these landscapes are under severe threats of land-use change which potentially pose direct threats to biodiversity, in particular through land-use intensification and land abandonment. Navigating biodiversity conservation in such changing landscapes requires a thorough understanding of the drivers that maintain the social-ecological system. This dissertation aimed to identify system properties that facilitate biodiversity conservation in traditional farming landscape, focusing specifically on birds and large carnivores in the rapidly changing traditional farmland region of Southern Transylvania, Romania. In order to identify these properties, I first examined the effects of local and landscape scale land-use patterns on birds and large carnivores and how they may be affected by future land-use change (Chapters II-V). Second, to gauge the role of particular traditional land-use elements for biodiversity I focused on the conservation value of traditional wood pastures (Chapters VI-VIII). Third, I took a social-ecological systems approach to understand how links between the social and ecological parts of the system affect human-bear coexistence (Chapters IV and IX). Bird diversity was supported by the broad gradients of woody vegetation cover and compositional heterogeneity. Land-use intensification, and hence the loss of woody vegetation cover and homogenization of land covers, would thus negatively affect biodiversity. This was especially evident from predictions on the distribution of the corncrake (Crex crex) in response to potential future land cover homogenization. Here, a moderate reduction of land cover diversity could drastically reduce the extent of corncrake habitat. Further results showed that the brown bear (Ursus arctos) would mainly be affected by land-use change through the fragmentation of large forest blocks, especially if land-use change would reduce habitat connectivity to the presumed source population in the Carpathian Mountains. Moreover, this dissertation revealed that large carnivores (brown bear and wolf, Canis lupus) may have important and often ignored roles in structuring the ecosystem of traditional farming landscapes by limiting herbivores. Wood pastures were found to have a high conservation value. The combination of low-intensity used grasslands with old scattered trees provided important supplementary habitat for different forest species such as woodpeckers and the brown bear. Worryingly, current management of wood pastures differed from traditional techniques in several aspects, which may threaten their persistence in the landscape. The majority of people had a positive perception on human-bear coexistence. The use of traditional sheep herding techniques combined with the tolerance of some shepherds to occasional livestock predation facilitated coexistence in a region where both carnivores and livestock are present. More generally, the genuine links between people and their environment were important drivers of people´s positive views on coexistence. However, perceived failures of top-down managing institutions could potentially erode these links and reduce people´s tolerance towards bears. Through the consideration of two different animal taxa, this dissertation revealed six important system properties facilitating biodiversity conservation in traditional farming landscapes. Similar proportions of the main land-use types (arable land, grassland, and forests) support species richness at the regional scale possible through habitat connectivity and continuous spill-over between land-use types. Heterogeneous landscapes can further support biodiversity through complementation and supplementation of habitat at the landscape scale. Gradients of woody vegetation cover and heterogeneity, supported biodiversity at both local and landscape scales possibly through the provision of a wide range of resources. The heterogeneous character of the landscape is tightly linked to traditional land-use practices, which also maintain specific traditional land-use elements and facilitate human-carnivore coexistence. Top-down limitation of large carnivores on herbivores possibly enhances vegetation growth and tree regeneration. The genuine links between humans and nature support human-bear coexistence, and these links may form the core of people´s values and sustainable use of natural resources.

Climate change and atmospheric deposition of nitrogen affect biodiversity patterns and functions of forest ecosystems worldwide. Many studies have quantified tree growth responses to single global change drivers, but less is known about the interaction effects of these drivers at the plant and ecosystem level. In the present study, we conducted a full-factorial greenhouse experiment to analyse single and combined effects of nitrogen fertilization (N treatment) and drought (D treatment) on 16 morphological and chemical response variables (including tissue δ13C signatures) of one-year-old Fagus sylvatica seedlings originating from eight different seed families from the Cantabrian Mountains (NW Spain). Drought exerted the strongest effect on response variables, reflected by decreasing biomass production and increasing tissue δ13C signatures. However, D and N treatments interacted for some of the response variables, indicating that N fertilization has the potential to strengthen the negative effects of drought (with both antagonistic and amplifying interactions). For example, combined effects of N and D treatments caused a sevenfold increase of necrotic leaf biomass. We hypothesize that increasing drought sensitivity was mainly attributable to a significant reduction of the root biomass in combined N and D treatments, limiting the plants’ capability to satisfy their water demands. Significant seed family effects and interactions of seed family with N and D treatments across response variables suggest a high within-population genetic variability. In conclusion, our findings indicated a high drought sensitivity of Cantabrian beech populations, but also interaction effects of N and D on growth responses of beech seedlings.

Ensuring food security and halting biodiversity loss are two of the most pressing global sustainability challenges. Traditionally food security and biodiversity conservation were treated as mutually exclusive goals, and as a result, discourses and approaches were developed separately around each of these goals. Recently, however, sustainability science increasingly recognizes the close interdependence of food security and biodiversity and hence, pays greater emphasis to the need for integration of the two goals. Navigating pathways to ensure the successful integration of the two goals is, therefore, an important requirement. Attempts to identify pathways toward such integration have been dominated with a biophysical-technical focus that provides technical solutions to the integration of food security and biodiversity conservation. To this end, different food production techniques, and agricultural land use strategies have been widely considered as a solution to the food security-biodiversity nexus. While much scholarly attention has been given to the biophysical-technical dimensions, the social-political dimension, including equity, governance, and empowerment received little to no attention. By focusing on the poorly investigated social-political dimension, this dissertation aimed to identify governance properties that facilitate and impede the integration of food security and biodiversity conservation through an empirical case study conducted in a multi-level governance setting of southwestern Ethiopia. To address the overarching goal of this dissertation, first I examined how the existing widely discussed food security approaches and agricultural land use framework, land sparing versus land sharing unfold in the local context of southwestern Ethiopia. The finding in this dissertation indicated that the existing global framing of food security approaches as well as frameworks around agricultural land use has limited applicability in on-the-ground realities mainly because landscapes are complex systems that consist of stakeholders with multiple and (often) conflicting interests. This was evident from the finding that, unlike the binary framing of agricultural land use as land sparing and land sharing, local land use preference was not a matter of ‘either/or’, but instead involved mixed features exhibiting properties of both land sparing and land sharing. Moreover, in addition to the biophysical factors embedded in the existing food security approaches and land use frameworks, stakeholders preference involved social factors such as the compatibility of land use strategy with local values and traditions, which are mainly unaccounted in the existing global frameworks. Findings in his dissertation revealed that the existing reductionist analytical framings to the issues of food security and biodiversity conservation seldom address the complexity inherent within and between food security and biodiversity conservation sectors. Second, this dissertation identified governance structural and process related challenges that influence individual as well as integrated achievements of food security and biodiversity conservation goals. The result of the study showed that the governance of food security and biodiversity conservation was characterized by a strongly hierarchical system with mainly linear vertical linkages, lacking horizontal linkages between stakeholders that would transcend administrative boundaries. This type of governance structure, where stakeholders interaction is restricted to administrative boundaries could not fit with the nature of food security and biodiversity conservation because the two goals are complex in their own involving sub-systems transcending different policy sectors and administrative boundaries. Furthermore, with regard to the governance process, three key and interdependent categories of governance process challenges namely, institutional misfit, the problem of interplay, and policy incoherence influenced the achievement of individual and integrated goals of food security and were identified. Given the interdependence of these governance challenges, coupled with the complexity inherent in the food security and biodiversity conservation, attempts to achieve the dual goals thus needs an integrative, flexible and adaptive governance system Third, to understand how food security and biodiversity conservation unfold in the future, I explored future development trajectories for southwestern Ethiopia. Iterative scenario planning process produced four plausible future scenarios that distinctly differed with regard to dominating land use strategies and crops grown, actor constellations and governance mechanisms, and outcomes for food security and biodiversity conservation. Three out of the four scenarios focused on increasing economic gains through intensive and commercial agricultural production. The agricultural intensification and commercialization may increase food availability and income gains, but negatively affect food security through neglecting other dimensions such as dietary diversity, social justice and stability of supply. It also affects biodiversity conservation by causing habitat loss, land degradation, and water pollution, biodiversity loss. In contrast, one scenario involved features that are widely considered as beneficial to food security and biodiversity conservation, such as agroecological production, diversification practices, and increased social-ecological resilience. In smallholder landscapes such as the one studied here, such a pathway that promises benefits for both food security and biodiversity conservation may need to be given greater emphasis. In order to ensure the integration of food security and biodiversity conservation, recognizing their interdependence and addressing the challenges in a way that fits with the local dynamics is essential. In addition, addressing the food security-biodiversity nexus requires a holistic analytical lens that enables proper identification of system properties that benefit food security and biodiversity conservation. Moreover, this dissertation indicated that there is a clear need to pay attention to the governance structure that accommodates the diversity of perspectives, enable participation and strong coordination across geographical boundaries, policy domains and governance levels. Finally, this dissertation revealed opportunities to integrate food security and biodiversity through the pro-active management of social-ecological interactions that produce a win-win outcome. The win-win outcome could be achieved in a system that involve properties such as diversification and modern agroecological techniques, smallholders empowerment, emphasize adaptive governance of social-ecological systems, value local knowledge, culture and traditions, and ensure smallholders participation. While such diversification and agroecological practices may lack the rapid economic development that is inherent to the conventional intensification, it essentially create a system that is more resilient to environmental and economic shocks, thereby providing a more sustainable long-term benefit.

Der hochwassergebundene Sedimenteintrag ist Motor der Bodenbildung in Auen. Der mit dem Sedimenteintrag einhergehende Schadstofftransport in die flussbegleitenden Auen ist Ursache für die Akkumulation von Schadstoffen in den aquatischen und semiterretrischen Systemen. Er wirkt in weiten Teilen der Elbauen nicht nur einschränkend auf die landwirtschaftliche Nutzung des Grünlandes sondern beeinträchtigt daneben auch weitere Schutzgüter, wie z. B. Habitate und Lebensgemeinschaften. Diese Arbeit hatte das Ziel, die Steuergrößen des Sediment- und Schadstoffeintrags anhand von langjährig erhobenen Messdaten zu untersuchen und gleichzeitig die zeitliche und räumliche Verbreitung ausgewählter Schadstoffe als Baustein eines belastungsangepassten Auenmanagements aufzuklären. Dafür wurden eigene Daten über Hochflutsedimente und Böden ebenso ausgewertet wie Daten anderer Autoren. Außerdem lag ein Schwerpunkt der Arbeit in der kombinierten Auswertung von Zeitreihen der Sedimentbelastung von Gewässern und von Auenböden, die eine Grundlage für das Verständnis des elbespezifischen Belastungsmosaiks von Böden mit Schwermetallen und Dioxinen/Furanen darstellt. Zunächst erfolgte eine detaillierte Recherche und Analyse der retentionsfördernden Eigenschaften der Elbauen. Es wurden abschnittsspezifische Flächengrößen, Landnutzungsunterschiede und Flächenbetroffenheiten bei unterschiedlichen Hochwasserzuständen herausgearbeitet. Mit Hilfe der darauf aufbauenden, datenbasierten Analysen über ereignisbezogene Sedimenteinträge in die Elbauen konnten wesentliche Steuergrößen des Sedimenteintrags identifiziert werden. Die Distanz der Standorte zur Elbe ist die wesentliche Kenngröße, sodass die größten Sedimenteinträge in Flussnähe stattfinden. Darüber hinaus ist die Höhe des Sedimenteintrags abflussabhängig. Auf dieser Grundlage wurde ein Ansatz zur Berechnung des großräumigen Sedimenteintrags entwickelt, mit dessen Hilfe die Retentionsfunktion der Auen im Abfluss- und Stofftransportgeschehen der Elbe abgeschätzt werden konnte. Die Sedimentretention der Elbauen hatte im Betrachtungszeitraum zwischen 2003 und 2008 einen Anteil von 7 bis 30 % an den Jahresschwebstofffrachten in Hitzacker. Die Analysen von verschiedenen Zeitreihen der Sediment- und Bodenbelastungen mit Schwermetallen, Arsen sowie Dioxinen/Furanen verdeutlichte, dass die Stoffgruppen ganz unterschiedliche Belastungsentwicklungen durchlaufen haben. Der Schwerpunkt der Dioxinkontamination in Sedimenten und Böden trat in den 1950er bis 1960er Jahren auf, während Metalle im Allgemeinen erst später Belastungsmaxima zeigten. Allerdings konnte mit dem Pb/Zn-Verhältnis ein Metallmuster identifiziert werden, mit dessen Hilfe auch in Oberböden auf der Basis von Metalldaten auf Dioxinbelastungen geschlossen werden konnte. Darüber hinaus wurde unter Kenntnis der spezifischen Belastungshistorien mittels Kategorisierung der Standorteigenschaften Höhenlage, Distanz, Bioturbation und Sedimenteintrag ein Erklärungsschema zur Vorhersage von räumlichen Schadstoffmustern für ausgewählte Metalle und Dioxine/Furane entwickelt. Sowohl die Untersuchungen zum Sedimentationsgeschehen als auch zur Aufklärung des Belastungsmosaiks in den Elbauen ließen Ableitungen von Maßnahmenvorschlägen zur Förderung der Sedimentationsdynamik, des Hochwasserschutzes, zur schadstoffspezifischen Verbesserung der Bodenbelastung als auch zur belastungsangepassten Landnutzung zu.

Habitat fragmentation and changes in land use are currently two major drivers of biodiversity loss around the world by causing habitat loss and reducing connectivity across landscapes. These processes affect not only species diversity, but genetic structure as well. The loss of habitat and the increased isolation prevent gene flow and accelerate genetic drift, causing loss of genetic diversity and facilitating development of genetic differentiation. The effects of habitat fragmentation and land use changes are usually studied by relating patterns of genetic diversity and differentiation to environmental factors, habitat history, landscape structure, or to a combination thereof. However, these three drivers are rarely addressed simultaneously. In addition, these studies are usually carried out in conservation-driven contexts, and therefore tend to concentrate on hyper-fragmented landscapes and on rare or endangered species. However, how habitat fragmentation and land use affect widespread species in more typical landscapes has not been fully investigated. In this thesis I address these two gaps, and do so in three study regions, allowing for generalization of the results. I used Abax parallelepipedus, a flightless ground beetle with low dispersal power as a model species to test how environmental factors, habitat history, and landscape structure affect genetic diversity and genetic differentiation in three study regions located across Germany. This species seldom leaves wooded habitats, and rarely crosses linear barriers such as roads and railways. It is also known to be susceptible to rapid changes in genetic structure after habitat fragmentation. Nevertheless, A. parallelepipedus is widely distributed as it can inhabit a variety of woodland types in which it maintains high population densities. Although all of my study regions represent fairly typical rural landscapes for central Europe, each consisting of a complex matrix of land uses, they differ from one another in terms of environmental factors, habitat history, and landscape structure, and thus can serve as three test cases. In the first stage of my work, I identified polymorphic microsatellite loci which could potentially be used to study genetic diversity and differentiation in A. parallelepipedus. I then developed PCR and genotyping protocols for two suites of loci, in the end selecting to use the set of 14 fully multiplexed loci for my study. After I had developed the needed study system, I genotyped over 3300 beetles from 142 study sites. In my investigation of how environmental factors and habitat history affect genetic diversity and genetic differentiation, I found that genetic diversity was being driven by variables that could be related to population sizes rather than by habitat history. I also did not find evidence of an influence of habitat history on the genetic differentiation patterns. Although populations of A. parallelepipedus in the past were probably smaller due to deforestation, they apparently remained large enough to prevent rapid genetic drift. Thus, recolonization processes of woodlands planted after the peak of deforestation either occurred without incurring founder effects or bottlenecks, or the effects of thereof have since been erased by gene flow. As the genetic structure found in my landscapes is driven current processes, rather than historical ones, I carried out a landscape genetics analysis of the genetic differentiation patterns found in each of my study regions, in which I examined the relationship between genetic differentiation and landscape structure. I tested whether I could find patterns of isolation by distance, isolation by resistance, or isolation by barriers in my study regions. Surprisingly, I found no effects of land use or of fragmentation. Based on the importance of population sizes found in my previous study, combined with the beetle´s known avoidance of non-wooded areas and its inability to cross roads, I conclude that although there is probably little gene flow across my study regions, large population sizes are preventing the rapid development of genetic differentiation. Models simulating the development of genetic differentiation over time in populations of different starting sizes support this conclusion. My work highlights the importance of population sizes in determining how patterns of genetic diversity and differentiation will develop across landscapes. While emphasis has been placed in conservation contexts on the deleterious effects of fragmentation on genetic structure, this may be overstated for widespread species in typical landscapes. In such cases, large population sizes may mitigate the development of genetic differentiation and prevent loss of alleles, despite existing barriers and lack of gene flow.