Elinor Ostrom challenges the view that states and markets alone have the potential to successfully regulate policymaking processes regarding long term sustainability of natural resources, promoting self-governing institution and communities in governing commons. Forestry management is concerned with administrative, social, environmental and economic aspects on forests and forestry resources, which in particular climates require adaptive measures accordingly with local environmental conditions. In Australia the fire-prone clima- te requires the inclusion of efficient and long-term sustainable fire management practices in order to protect ecosystems, natural resources and the population. Recent events such as destructive fire seasons and global spread of diseases brought attention to efficiency of current management strategies and promote the inve- stigation of indigenous and traditional knowledge, seen with potential for long-term sustainability, ecosy- stem restoration, and climate mitigation. Aboriginal fire management practices undertaken in the Kimberley Region and the Northern Territory of Australia are investigated and evaluated accordingly with socio-eco- nomic, environmental and societal standards, to create an overall scenario where fire is understood as a common resource, manageable and equally valuable as water and land. If seen as a common and managed as such, fire can be beneficial for long term sustainability, with the potential to address biodiversity conser- vation, resource management practices, and climate change mitigation.

Fire, logging, livestock grazing, and insect outbreaks are disturbances that have significantly influenced both the historic and present fire regimes. The composition and structure of vegetation communities within Great Smoky Mountains National Park (GSMNP) have likely changed in response to these disturbances. Two study sites (CRX, the near site, and CRT, the far site) were chosen along the Cooper Road Trail based on topographic separation, presence of mixed oak-pine communities, presence of fire-scarred yellow pine trees, and GSMNP land acquisition records. To quantify and evaluate fire regimes, individual fire histories were developed for each site from fire-scarred yellow pine trees, and two 1000 m2 (0.1 ha) study plots were established for vegetation surveys. Fire history analysis yielded mean fire intervals of 6.2 years at the near site, 3.4 years at the far site, and 3.2 years when combined. Spatial analysis showed significant differences in fire activity between study sites. Temporal analysis showed significant differences in mean fire intervals between the pre-settlement (1720–1818) and post-settlement periods (1819–1934). Superposed epoch analysis showed the over-riding influence of climate at these sites. At the near site, trees displayed greater species diversity, larger diameter, and older age. Eastern white pine, pitch pine, red maple, and black gum were the dominant species. At the far site, tree species diversity was lower and trees were generally younger. Mixed oak-pine communities are succeeding to a canopy dominated by shade-tolerant, fire-sensitive species such as eastern white pine and red maple. Without fire disturbance, yellow pine communities will cease to regenerate, as will oak species that prefer a fire-maintained habitat.

Fire, logging, livestock grazing, and insect outbreaks are disturbances that have significantly influenced both the historic and present fire regimes. The composition and structure of vegetation communities within Great Smoky Mountains National Park (GSMNP) have likely changed in response to these disturbances. Two study sites (CRX, the near site, and CRT, the far site) were chosen along the Cooper Road Trail based on topographic separation, presence of mixed oak-pine communities, presence of fire-scarred yellow pine trees, and GSMNP land acquisition records. To quantify and evaluate fire regimes, individual fire histories were developed for each site from fire-scarred yellow pine trees, and two 1000 m2 (0.1 ha) study plots were established for vegetation surveys. Fire history analysis yielded mean fire intervals of 6.2 years at the near site, 3.4 years at the far site, and 3.2 years when combined. Spatial analysis showed significant differences in fire activity between study sites. Temporal analysis showed significant differences in mean fire intervals between the pre-settlement (1720–1818) and post-settlement periods (1819–1934). Superposed epoch analysis showed the over-riding influence of climate at these sites. At the near site, trees displayed greater species diversity, larger diameter, and older age. Eastern white pine, pitch pine, red maple, and black gum were the dominant species. At the far site, tree species diversity was lower and trees were generally younger. Mixed oak-pine communities are succeeding to a canopy dominated by shade-tolerant, fire-sensitive species such as eastern white pine and red maple. Without fire disturbance, yellow pine communities will cease to regenerate, as will oak species that prefer a fire-maintained habitat.

xiv, 227 p. : ill. (some col.) A print copy of this title is available through the UO Libraries under the call numbers: KNIGHT QE720.2.K53 B75 2008 / The Holocene vegetation and fire history of the Klamath Mountains (KM), northern California, was reconstructed at three sites based on an analysis of pollen and high-resolution macroscopic charcoal in lake-sediment cores. These data were compared with five existing records to examine regional patterns. The objective was to determine the relative importance of climate history, substrate, and disturbance regime on the development of the Klamath vegetation. In the first study, two middle-elevation sites were compared along a moisture gradient in the northern KM. The pollen data indicated a similar vegetation history, beginning with subalpine parkland in the late-glacial period, and changing to open forest in the early Holocene and closed forest in the late Holocene. However, the timing of these changes differed between sites and is attributed to the relative importance of coastal influences and topography. The second study examined the effect of substrate and nutrient limitations on the vegetation history. The pollen data suggest that ultramafic substrates (UMS), containing heavy metals and low nutrients that limit plant growth, supported drier plant communities than those on non-ultramafic substrates (NUMS) for any given period. For example, between 14,000 and 11,000 cal yr BP, cooler and wetter conditions than present led to the establishment of a subalpine parkland of Pinus monticola and/or Pinus lambertina, Tsuga, Picea on non-ultramafic substrates (NUMS). On UMS, an open Pinus jeffreyi and/or Pinus contorta woodland developed. In the early Holocene, when conditions were warmer and drier than present, open forests of Pinus monticola/lambertina , Cupressaceae, Quercus and/or Amelanchier grew on NUMS, whereas open forest consisting of Pinus Jeffreyi/contorta , Cupressaceac and Quercus developed on UMS. In the late Holocene, cool wet conditions favored closed forests of Abies, Pseudotsuga , and Tsuga on NUMS, whereas Pinus jeffreyi/contorta , Cupressaceae and Quercus forest persisted with little change on UMS. The charcoal data indicate that past fire activity was similar at all sites, implying a strong climatic control. The results of both studies suggest that the influence of Holocene climate variations, disturbance regime, and substrate type have helped create the current mosaic of vegetation in the KM. / Adviser: Cathy Whitlock, Patrick Bartlein

Human disruption of climate, habitat, and ignition has altered the behavior of wildland fire at local to continental scales. In many regions, novel fire regimes are emerging that threaten to exceed the capacity for local management to protect human wellbeing and ecosystem function. Simultaneous changes in climate, species composition, and fire management have resulted in extreme fire behavior in many regions. For the Western United States, the emerging novel fire regime consists of more frequent, severe, and intense wildfires, with annual area burned by wildfire having doubled and high-severity wildfire area having increased 8-fold since the 1980s. The impacts of these increasing stresses in the Great Basin is especially pressing when combined with the many years of historically poor resource management. Here we complete a literature review of changing wildfire regimes globally (chapter 1) and a study of how the abiotic and biotic aspects of aquatic ecosystems stabilize after a megafire in the western United States (chapter 2).

Untersuchungen zur Rolle natürlicher Störungen in der Vegetation bzw. in Ökosystemen zeigen, dass natürliche Störungen ein essentielles und intrinsisches Element in Ökosystemen darstellen, substanziell zur Vitalität und strukturellen Diversität der Ökosysteme beitragen und Stoffkreisläufe sowohl auf dem lokalen als auch auf dem globalen Niveau beeinflussen. Feuer als Grasland-, Busch- oder Waldbrand ist ein besonderes Störungsagens, da es sowohl durch biotische als auch abiotische Umweltfaktoren verursacht wird. Es beeinflusst biogeochemische Kreisläufe und spielt für die chemische Zusammensetzung der Atmosphäre durch Freisetzung klimarelevanter Spurengase und Aerosole aus der Verbrennung von Biomasse eine bedeutende Rolle. Dies wird auch durch die Emission von ca. 3.9 Gt Kohlenstoff pro Jahr unterstrichen, was einen großen Anteil am globalen Gesamtaufkommen ausmacht.<br /> <br /> Ein kombiniertes Modell, das die Effekte und Rückkopplungen zwischen Feuer und Vegetation beschreibt, wurde erforderlich, als Änderungen in den Feuerregimes als Folge von Änderungen in der Landnutzung und dem Landmanagement festgestellt wurden. Diese Notwendigkeit wurde noch durch die Erkenntnis unterstrichen, daß die Menge verbrennender Biomasse als ein bedeutender Kohlenstoffluß sowohl die chemische Zusammensetzung der Atmosphäre und das Klima, aber auch die Vegetationsdynamik selbst beeinflusst. Die bereits existierenden Modellansätze reichen hier jedoch nicht aus, um entsprechende Untersuchungen durchzuführen. Als eine Schlussfolgerung daraus wurde eine optimale Menge von Faktoren gefunden, die das Auftreten und die Ausbreitung des Feuers, sowie deren ökosystemare Effekte ausreichend beschreiben. Ein solches Modell sollte die Merkmale beobachteter Feuerregime simulieren können und Analysen der Interaktionen zwischen Feuer und Vegetationsdynamik unterstützen, um auch Ursachen für bestimmte Änderungen in den Feuerregimes herausfinden zu können. Insbesondere die dynamischen Verknüpfungen zwischen Vegetation, Klima und Feuerprozessen sind von Bedeutung, um dynamische Rückkopplungen und Effekte einzelner, veränderter Umweltfaktoren zu analysieren. Dadurch ergab sich die Notwendigkeit, neue Feuermodelle zu entwickeln, die die genannten Untersuchungen erlauben und das Verständnis der Rolle des Feuer in der globalen Ökologie verbessern.<br /> <br /> Als Schlussfolgerung der Dissertation wird festgestellt, dass Feuchtebedingungen, ihre Andauer über die Zeit (Länge der Feuersaison) und die Streumenge die wichtigsten Komponenten darstellen, die die Verteilung der Feuerregime global beschreiben. Werden Zeitreihen einzelner Regionen simuliert, sollten besondere Entzündungsquellen, brandkritische Klimabedingungen und die Bestandesstruktur als zusätzliche Determinanten berücksichtigt werden. Die Bestandesstruktur verändert das Niveau des Auftretens und der Ausbreitung von Feuer, beeinflusst jedoch weniger dessen interannuelle Variabilität. Das es wichtig ist, die vollständige Wirkungskette wichtiger Feuerprozesse und deren Verknüpfungen mit der Vegetationsdynamik zu berücksichtigen, wird besonders unter Klimaänderungsbedingungen deutlich. Eine länger werdende, vom Klima abhängige Feuersaison bedeutet nicht automatisch eine im gleichen Maße anwachsende Menge verbrannter Biomasse. Sie kann durch Änderungen in der Produktivität der Vegetation gepuffert oder beschleunigt werden. Sowohl durch Änderungen der Bestandesstruktur als auch durch eine erhöhte Produktivität der Vegetation können Änderungen der Feuereigenschaften noch weiter intensiviert werden und zu noch höheren, feuerbezogenen Emissionen führen. / Studies of the role of disturbance in vegetation or ecosystems showed that disturbances are an essential and intrinsic element of ecosystems that contribute substantially to ecosystem health, to structural diversity of ecosystems and to nutrient cycling at the local as well as global level. Fire as a grassland, bush or forest fire is a special disturbance agent, since it is caused by biotic as well abiotic environmental factors. Fire affects biogeochemical cycles and plays an important role in atmospheric chemistry by releasing climate-sensitive trace gases and aerosols, and thus in the global carbon cycle by releasing approximately 3.9 Gt C p.a. through biomass burning. <br /> <br /> A combined model to describe effects and feedbacks between fire and vegetation became relevant as changes in fire regimes due to land use and land management were observed and the global dimension of biomass burnt as an important carbon flux to the atmosphere, its influence on atmospheric chemistry and climate as well as vegetation dynamics were emphasized. The existing modelling approaches would not allow these investigations. As a consequence, an optimal set of variables that best describes fire occurrence, fire spread and its effects in ecosystems had to be defined, which can simulate observed fire regimes and help to analyse interactions between fire and vegetation dynamics as well as to allude to the reasons behind changing fire regimes. Especially, dynamic links between vegetation, climate and fire processes are required to analyse dynamic feedbacks and effects of changes of single environmental factors. This led us to the point, where new fire models had to be developed that would allow the investigations, mentioned above, and could help to improve our understanding of the role of fire in global ecology. <br /> <br /> In conclusion of the thesis, one can state that moisture conditions, its persistence over time and fuel load are the important components that describe global fire pattern. If time series of a particular region are to be reproduced, specific ignition sources, fire-critical climate conditions and vegetation composition become additional determinants. Vegetation composition changes the level of fire occurrence and spread, but has limited impact on the inter-annual variability of fire. The importance to consider the full range of major fire processes and links to vegetation dynamics become apparent under climate change conditions. Increases in climate-dependent length of fire season does not automatically imply increases in biomass burnt, it can be buffered or accelerated by changes in vegetation productivity. Changes in vegetation composition as well as enhanced vegetation productivity can intensify changes in fire and lead to even more fire-related emissions. <br><br> ---<br> Anmerkung:<br> Die Autorin ist Trägerin des von der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Potsdam vergebenen Michelson-Preises für die beste Promotion des Jahres 2002/2003.

Lightning-caused forest fires are one of the major natural disturbances in Ontario managed boreal forests. Survival of these forests with fires for centuries shows that such disturbances are integral to the boreal ecosystem and its ecological functioning. Characterizing the fire regimes defined by fire ignition frequency, fire sizes and their spatial distribution patterns etc. thus can help to improve our understanding of the boreal forest dynamics and provide guidance for management practices attempting to maintain biodiversity and achieve sustainability. In this thesis the lightning-caused fire ignitions data for four ecoregions in Ontario managed boreal forests (3E, 3W, 3S and 4S) for 1960–2009 were analyzed using pattern analysis and density estimation to determine the spatial nature of fire ignitions. These fire ignition spatial patterns were further used (as weighted ignition scenario) to simulate forest fire regimes in the study area. Fire regimes were also simulated using spatially unweighted ignitions (unweighted ignition scenario). Non-spatial (total number of fires, total burn area, number of fires by size classes, annual burn fraction) and spatial (spatial burn probability) indicators of the simulated fire regimes under both ignition scenarios were compared to test the null hypothesis that modeled forest fire regime is not affected by the spatial patterns of input fire ignitions. All data analysis were performed for individual ecoregions. Spatial pattern of ignitions were analyzed using the nearest neighbour index and Ripley’s K-function. Ignition densities were estimated using the adaptive kernel density estimation method and the fire regimes were simulated using BFOLDS (Boreal Forests Landscape Dynamics Simulator). Results showed that lightning-caused fire ignitions are clustered in all ecoregions. Fire ignition density also varied spatially within ecoregions. Overall fire ignition density was highest in the northwestern ecoregion (4S) and lowest in the eastern ecoregion (3E), which corresponds to the combined gradient of effective humidity and temperature in Ontario. For each ecoregion, comparison of non-spatial simulated fire regime indicators showed statistically non-significant differences between unweighted and weighted ignitions. The spatial burn probability however captured clear spatial differences between unweighted and weighted ignitions. Spatial differences in spatial burn probability between both ignition scenarios were more prominent in ecoregions of high fire occurrence. Results of the weighted ignition scenario closely followed the spatial patterns of the estimated fire ignition density in the study area. Based on these results this thesis rejects the null hypothesis and emphasizes that ignition patterns must be considered in simulating fire regime in Ontario boreal forests.

Lightning-caused forest fires are one of the major natural disturbances in Ontario managed boreal forests. Survival of these forests with fires for centuries shows that such disturbances are integral to the boreal ecosystem and its ecological functioning. Characterizing the fire regimes defined by fire ignition frequency, fire sizes and their spatial distribution patterns etc. thus can help to improve our understanding of the boreal forest dynamics and provide guidance for management practices attempting to maintain biodiversity and achieve sustainability. In this thesis the lightning-caused fire ignitions data for four ecoregions in Ontario managed boreal forests (3E, 3W, 3S and 4S) for 1960–2009 were analyzed using pattern analysis and density estimation to determine the spatial nature of fire ignitions. These fire ignition spatial patterns were further used (as weighted ignition scenario) to simulate forest fire regimes in the study area. Fire regimes were also simulated using spatially unweighted ignitions (unweighted ignition scenario). Non-spatial (total number of fires, total burn area, number of fires by size classes, annual burn fraction) and spatial (spatial burn probability) indicators of the simulated fire regimes under both ignition scenarios were compared to test the null hypothesis that modeled forest fire regime is not affected by the spatial patterns of input fire ignitions. All data analysis were performed for individual ecoregions. Spatial pattern of ignitions were analyzed using the nearest neighbour index and Ripley’s K-function. Ignition densities were estimated using the adaptive kernel density estimation method and the fire regimes were simulated using BFOLDS (Boreal Forests Landscape Dynamics Simulator). Results showed that lightning-caused fire ignitions are clustered in all ecoregions. Fire ignition density also varied spatially within ecoregions. Overall fire ignition density was highest in the northwestern ecoregion (4S) and lowest in the eastern ecoregion (3E), which corresponds to the combined gradient of effective humidity and temperature in Ontario. For each ecoregion, comparison of non-spatial simulated fire regime indicators showed statistically non-significant differences between unweighted and weighted ignitions. The spatial burn probability however captured clear spatial differences between unweighted and weighted ignitions. Spatial differences in spatial burn probability between both ignition scenarios were more prominent in ecoregions of high fire occurrence. Results of the weighted ignition scenario closely followed the spatial patterns of the estimated fire ignition density in the study area. Based on these results this thesis rejects the null hypothesis and emphasizes that ignition patterns must be considered in simulating fire regime in Ontario boreal forests.

Das Amazonasgebiet hat in den letzten Jahrzehnten eine Intensivierung der menschlichen Aktivitäten erfahren, die in Verbindung mit häufigen schweren Dürren die Umwelt anfälliger für Brände gemacht hat. In dieser Dissertation wurden Fernerkundungsdaten analysiert, um die räumlich-zeitliche Verteilung der Feuer in den letzten 20 Jahren im brasilianischen Amazonasgebiet umfassend zu untersuchen und die verschiedenen Brandursachen zu entschlüsseln. (I) Die erste Forschungsarbeit wertete die Verteilung der verbrannten Fläche aus und zeigte, dass die meisten Brände auf bewirtschafteten Weiden und in den immergrünen Tropenwäldern auftraten, was die Behauptung stützt, dass ihr Auftreten stark auf anthropogene Landnutzungsänderungen reagiert. Die Ergebnisse zeigten auch, dass weder Entwaldung noch Walddegradierung mit Waldbränden korrelierte, wohl aber Feuer, die auf Weiden oder Ackerflächen gelegt wurden und in den angrenzenden Wald übergesprungen sind. (II) Die zweite Forschungsarbeit analysierte einzelne Brände, die durch den auf komplexen Netzwerken basierenden FireTracks-Algorithmus identifiziert wurden. Der Algorithmus wurde verwendet, um Feuerregime für sechs verschiedene Landnutzungsklassen zu ermitteln. Die integrierte Größe, Dauer, Intensität und Ausbreitungsrate dieser räumlich-zeitlichen Brandcluster in den verschiedenen Landnutzungstypen zeigte auf, wie seltene Waldbrände, die natürlicherweise nicht in immergrünen tropischen Wäldern vorkommen, sich zu einem Feuerregime entwickelten, das für Savannenbrände typisch ist. (III) Die dritte Forschungsarbeit analysierte extreme, d. h. die intensivsten Einzelfeuer in immergrünen tropischen Wäldern, und zeigte deren großen Anteil an der insgesamt verbrannten Waldfläche. Während der globale Klimawandel das Potenzial hat, die Trockenheit zu verstärken, sind die anthropogenen Ursachen der Waldzerstörung die Zündquellen, die die Verteilung extremer Brände in den empfindlichen tropischen Wäldern bestimmen. / The Amazon region has experienced an intensification of human activities in the last decades, which combined with frequent severe droughts has led to an environment more susceptible to fire. Remotely sensed data is employed to comprehensively analyse the spatio-temporal fire distribution in the Brazilian Legal Amazon over the past 20 years to disentangle the diverse fire drivers in the region. Special focus is given to burned tropical evergreen forests.  (I) The evaluation of the burned area distribution revealed that most of it occurred in pastures and tropical evergreen forests, supporting the claim that fire incidence responds strongly to anthropogenic land-use changes. The results also showed that neither deforestation nor degradation correlated with forest fires, but escaping fires from pastures and agriculture do. (II) The analysis of individual fires identified by the complex networks based FireTracks algorithm led to the characterization of six different land cover-dependent fire regimes (fire size, duration, intensity, and rate of spread), which uncovered how evergreen forest fires have escalated from being naturally rare to showing characteristics more typical of savanna fires. (III) The analysis of extreme (most intense) fires in evergreen forests showed their large contribution to the total forest burned. While global climate change has the potential to increase drought conditions, anthropogenic drivers of forest degradation provide the ignition sources that determine extreme fire distribution in the tropical forests. The findings call for the development of control and monitoring plans to prevent fires from escaping from managed lands into forests, better management techniques to support effective land use and ecosystem management, targeting forest degradation in addition to deforestation, and considering the human factor in fire ignition and spread in Dynamic Global Vegetation Models in order to reduce uncertainty in fire regime projections.