Diss. (sammanfattning) Umeå : Sveriges lantbruksuniversitet, 2009. / Härtill 4 uppsatser.

In a series of three studies, we assess modern debris-flow hazards in Arizona from extreme precipitation events and following wildfires. In the first study, we use a combination of surficial geologic mapping, ¹⁰Be exposure age dating and modeling to assess prehistoric to modern debris-flow deposits on two alluvial fans in order to place debris-flow hazards in the context of both the modern environment and the last major period of climate change. Late Pleistocene to early Holocene debris flows were larger and likely initiated by larger landslides or other mass movement failures, unlike recent debris flows that typically initiate from shallow (~1 m) failures and scour channels, thus limiting total volumes. In the second study we assess the predictive strengths of existing post wildfire debris-flow probability and volume models for use in Arizona's varied physiographic regions, and define a new rainfall threshold valid for Arizona. We show that all of the models have adequate predictive strength throughout most of the state, and that the debris-flow volume model over-predicts in all of our study areas. Our analysis shows that the choice of a model for a hazard assessment depends strongly on location. The objectively defined rainfall intensity-duration thresholds of I₁₀ and I₁₅ (52 and 42 mm h⁻¹, respectively) have the strongest predictive strengths, although all five of the threshold models performed well. In the third study, we explore various basin physiographic and soil burn severity factors to identify patterns and criteria that can be used to discriminate between potential non-debris-flow (nD) and debris-flow (D) producing basins. Findings from this study show that a metric of percent basins area with high soil burn severity on slopes ≥30 degrees provides a stronger discrimination between nD and D basins than do basin metrics, such as mean basin gradient or relief. Mean basin elevation was also found to discriminate nD from D basins and is likely a proxy for forest type and density, which relates to soil thickness, root density and the magnitude of post-disturbance erosion. Finally, we found that post-fire channel heads formed at essentially the same slope range (~30-40 degrees) as saturation-induced hill slope failures.

Since European settlement, alpine and sub-alpine grasslands in Victoria have been grazed more intensively and wildfires have become more frequent. Alpine plants, however, have primarily evolved in the absence of fire and grazing, suggesting that they might be particularly sensitive to these factors. Little is known about the short-term physiological responses to defoliation of these predominantly resprouting plants, and this thesis investigates changes in the carbohydrate storage reserves of alpine plants during recovery from fire and/or grazing. (For complete abstract open document)

[Truncated abstract] In this thesis, I address the modelling and computer simulation of spatial, eventdriven systems from a computer science perspective. Spatially explicit models of wildland fire (wildfire) behaviour are addressed as the specific application domain. Wildfire behaviour is expressed as a formal model and the associated simulations are compared to existing models and implementations. It is shown that the in- teracting spatial automata formalism provides a general framework for modelling spatial event-driven systems and is appropriate to wildfire systems. The challenge adressed is that of physically realistic modelling of wildfire behaviour in heterogeneous environments . . . Many current models do not incorporate the influence of a neighbourhood (the geometry of the fire front local to an unburnt volume of fuel, for example), but rather determine the propagation of fire using only point information. Whilst neighbourhood-based influence of behaviour is common to cellular automata theory, its use is very rare in existing models of wildfire models. In this thesis, I present the modelling technique and demonstrate its applicability to wildfire systems via a series of simulation experiments, where I reproduce known spatial wildfire dynamics. I conclude that the interacting spatial automata formalism is appropriate as a basis for constructing new computer simulations of wildfire spread behaviour. Simulation results are compared to existing implementations, highlighting the limitations of current models and demonstrating that the new models are capable of greater physical realism.

Thesis (MA)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2007. / Härtill 5 uppsatser.

Thesis (Ph. D.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 97-103). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2007. / Printout. Includes bibliographical references (leaves 50-58). Also available on the World Wide Web.

Grazing by large herbivores has the potential to provide multiple ecosystem services, depending on multiple factors. Through a range of interdisciplinary methods, including literature reviews, case studies, and semi-structured interviews, I seek to assess how grazing can contribute to sustainable landscape management, as well as how sustainable practices can be incentivised. In chapter one, I focus on the role of grazing in wildfire prevention. Through a systematic literature review, I uncover new insights into the effectiveness of large herbivores in mitigating wildfires. I find that large herbivores can reduce wildfire frequency by promoting grass-dominated landscapes and reduce fire intensity by consuming vegetation and creating landscape features that reduce fuel loads. However, the effectiveness of large herbivores depends on the type of vegetation and diet preferences of the animals, and management practices associated with livestock grazing can also influence fire ignition. In chapter two, I investigate the relationship between grazing management and ecosystem services through a literature review, focusing on synergies and trade-offs between them. I identify management practices that are beneficial to multiple ecosystem services as well as policy mechanisms that can incentivise them. In the third chapter, I use case studies to investigate the role of domestic animals in rewilding projects. I describe how domestic and semi-wild herbivores can contribute to rewilding projects and make them more inclusive for rural and indigenous communities. In the fourth chapter, I aim to identify the challenges faced by land users in performing sustainable grazing management through semi-structured interviews with 88 land users from eight case studies in Europe. I gain insights into land users' determinants of behaviour towards sustainable grazing practices using the Behaviour Change Wheel framework. Overall I suggest that grazing can be a potential solution to the challenges of the Anthropocene, but only when done in the right way. I emphasize the importance of an interdisciplinary approach in grazing research and considering socio-ecological systems. I also highlight the potential of rewilding and semi-wild grazing systems especially in areas undergoing land abandonment. The results imply a shift in meat production and consumption and potential new pathways for human-livestock relations. Finally, agricultural policies such as the Common Agricultural Policy (CAP) can play a crucial role in incentivizing sustainable grazing management and should be improved to support extensive grazing and extensification.:Table of Contents i. General Introduction 6 i.i Context 7 i.i.i European grazed landscapes can provide high biodiversity and supply various ecosystem services 7 i.i.ii Challenges for European grazed systems 9 i.ii Thesis methods and outline 13 i.ii.i Literature reviews (chapters 1 & 2) 13 i.ii.ii Case studies (chapters 3 and 4) 13 i.ii.iii General approach and methodological considerations 18 i.ii.iv Research aims and questions 18 i.ii.v Thesis outline 19 i.iii Graphical abstract 21 1. Chapter One 22 1.1 Introduction 23 1.2 Literature search 25 1.3 Overall effects of herbivores on wildfire risks 26 1.3.1 Effects of herbivores on wildfire frequency 26 1.3.2 Effects of herbivores on fire intensity or severity 30 1.4 Effects of herbivores on fuel loads and fire hazard 30 1.5 Effects of vegetation characteristics on fire regimes 33 1.6 Effects of grazing-associated management on wildfires 33 1.7 Implications for management 34 1.8 Implications for policy 36 1.9 Conclusions and future challenges 37 2. Chapter Two 38 2.1 Introduction 39 2.2 Literature review: general methods 42 2.3 Results 44 2.3.1 Effects of grazing on biodiversity 44 2.3.2 Effects of grazing on climate change and its mitigation 46 2.3.3 Effects of grazing on soil quality 48 2.3.4 Effects of grazing on wildfire mitigation 49 2.3.5 Effects of grazing on cultural ecosystem services 51 2.3.6 Synergies and Trade-offs of different grazing practices and ecosystem services 52 2.3.7 Recommendations: optimizing ecosystem multifunctionality in grazed systems 55 2.4 Outlook 59 3. Chapter Three 60 3.1 Introduction 61 3.2 The Broader Theory of Rewilding and Potential Role for Livestock 64 3.2.1 Stochastic Disturbance Regimes 64 3.2.2 Trophic Complexity 65 3.2.3 Interacting Processes 66 3.3 General Case Studies 67 3.3.1 Reindeer Engineer in Swedish Lapland 67 3.3.2 Livestock Fire Brigade and Free Running Horses in the Côa Valley, Portugal 68 3.3.3 Ecotourism and Sustainable Meat at Knepp Estate, England 70 3.3.4 Oostvaardersplassen: The “Wild Experiment” 71 3.4 Conclusions 73 4. Chapter Four 77 4.1 Introduction 78 4.2 Methods 80 4.2.1 Interviews 80 4.3 Findings from interviews: Determinants of sustainable grazing decisions 81 4.3.1 Physical capability: the impact of the ‘rural exodus’ 81 4.3.2 Psychological capability: access to knowledge and understanding of administrative rules influences how land users conduct their management 82 4.3.3 Physical opportunity 83 4.3.4 Social opportunities 85 4.3.5 Motivation 85 4.4 Discussion 87 4.4.1 Intervention functions to support sustainable grazing, and associated policies 88 4.5 Conclusions and outlook 92 5. Discussion 93 5.1 Importance of the scientific, social and political context of the research 93 5.2 Societal relevance of the thesis 93 5.3 Policy relevance of grazing research 94 5.4 The value of transdisciplinary research 94 5.5 Contribution of the research 95 5.5.1 Contribution of chapter 1: large herbivores and wildfire mitigation 95 5.5.2 Contribution of chapter 2: grazing and multiple ecosystem services, trade-offs and synergies in a European context 96 5.5.3 Contribution of chapter 3: domestic livestock and rewilding 97 5.5.4 Contribution of chapter 4: drivers of decision making for sustainable grazing 98 5.5.5 Interdisciplinary approach to grazing research, grazing areas as socio-ecological systems 99 5.6 Limitations 100 5.6.1 The framework of ecosystem services 100 5.6.2 Limitations to rewilding research 101 5.6.3 The challenge of addressing different socioecological and administrative scales 101 5.6.4 Practical limitations 103 6. Outlook 104 6.1 Future research needs 104 6.2 Pathways for sustainable grazing 104 7. Conclusion 107 References 110 Summary 135 Zusammenfassung 139 Appendix 143 Appendix Chapter One 144 Appendix Chapter Two 145 Appendix Chapter Four 149 Acknowledgements 153 Author contribution statement 155

We propose a new atmospheric model based on first-principles for the simulation of clouds. Our approach is able to simulate the realistic formation of various cloud types, such as cumulus, stratus, stratocumulus, their temporal evolution, and transitions between cloud types. Moreover, we are able to model strongly rotating thunderstorms known as supercells. Our method allows us to simulate cloud formations of up to about 20 km 20 km at interactive rates. For the intuitive exploration, we identified a light-weight parameter set to interactively explore cloud formations. We demonstrate that our model can be coupled with data from real-time weather services to simulate cloud formations in the now. Moreover, we present a novel approach for the simulation of wildfires. Our model is able to realistically capture the combustion process of trees, heat transfer with the environment and fire propagation between trees. We demonstrate that our approach is capable of realistically simulating the propagation of fire through entire ecosystems with varying vegetation occupancy. We integrated our atmospheric model which allows us to simulated clouds emerging from the evaporation of water from burning trees leading to complex so called flammagenitus patterns which are usually observed over wildfires. Our system runs at interactive rates which enables the exploration of wildfires in different environments.