As fire burns : functional work and praxis in ontology

The context: the historical and philosophical demise of the Marxist model of praxis as a unity of theory and practice organized by a Party in service of a Cause. The task: to remodel praxis by distinguishing it from functional work. The proving ground: the discourse of ontology. The thesis works through four types of ontology in its attempt to construct different ontological schemas for praxis and functional work. In the first three ontologies, Platonic, Aristotelian and relativist, ontological impasses occur in the accounts of the relation between one and the multiple, and of the existence of order. They prevent the successful construction of a schema for functional work. It is in the set-theory ontology of Alain Badiou that the means arise for the passage through these impasses and the definitive construction of distinct ontological schemas for functional work and praxis. This results in a new concept of praxis and a multiplication of its domains beyond politics to science, art and love

Fire management for biodiversity conservation : key research questions and our capacity to answer them

Knowing how species respond to fire regimes is essential for ecologically sustainable management. This axiom raises two important questions: (1) what knowledge is the most important to develop and (2) to what extent can current research methods deliver that knowledge? We identify three areas of required knowledge: (i) a mechanistic understanding of species’ responses to fire regimes; (ii) knowledge of how the spatial and temporal arrangement of fires influences the biota; and (iii) an understanding of interactions of fire regimes with other processes. We review the capacity of empirical research to address these knowledge gaps, and reveal many limitations. Manipulative experiments are limited by the number and scope of treatments that can be applied, natural experiments are limited by treatment availability and confounding factors, and longitudinal studies are difficult to maintain, particularly due to unplanned disturbance events. Simulation modelling is limited by the quality of the underlying empirical data and by uncertainty in how well model structure represents reality. Due to the constraints on large-scale, long-term research, the potential for management experiments to inform adaptive management is limited. Rather than simply recommending adaptive management, we define a research agenda to maximise the rate of learning in this difficult field. This includes measuring responses at a species level, building capacity to implement natural experiments, undertaking simulation modelling, and judicious application of experimental approaches. Developing ecologically sustainable fire management practices will require sustained research effort and a sophisticated research agenda based on carefully targeting appropriate methods to address critical management questions.

Simulation and visualization of fire using extended Lindenmayer systems

This research introduces a method of using Lindenmayer Systems to model the spreading and behavior of fire inside a factory building. The research investigates the use of L-System propagated fires for determining factors such as where the fire is most likely to spread first and how fast. It also looks at an alternative way of storing the Lindenmayer System, not in the form of a string but rather as a graph. A variation on the building and traversal process is also investigated, in which the L-System is traversed depth first instead of breadth first. Results of fire propagation are presented and we conclude that L-Systems are a suitable tool for fire propagation.

Paper and fire : the images and ashes of Rudolf Steiner's architecture

On New Years Eve, 1922, the massive double-domed timber structure of Rudolf Steiner’s First Goetheanum was engulfed in flames and reduced to ashes. In an effort to make his spiritual teachings accessible to all people through the medium of architecture, Steiner had dedicated ten years to the project. Growing hostility towards his occult philosophy however, pointed to arson as the probable cause of the blaze. Not to be defeated, Steiner embarked upon a new design for a second Goetheanum that endeavoured to fulfil the same aim as its predecessor but on an even grander scale. Yet despite being borne out of the same ideational basis, the architectural expression of the second building was vastly different from the first. This paper examines these differences and investigates how the methods Steiner used to create his architecture influenced the final architectural products. Steiner recognised drawing as a creative instrument that could enrich the conceptual potential of his theoretical work, however, with no formal training as an architect and limited drawing ability, this exchange was somewhat limited. The ambiguity of Steiner’s drawings is countered to some extent though by the maquettes and models he produced, which help negotiate the gap between the immaterial idea and the material object. The shared three-dimensional nature of model making and architecture allowed Steiner a more direct means of articulating and mediating his esoteric ideas in built form than the two-dimensional nature of drawing, particularly given the undulating organic forms he enthusiastically employed. Nevertheless, models are still a form of architectural abstraction capable of leaving their own trace on the built work and the distinctive character of Steiner’s non-conventional models serve to illustrate this point. A comparison between Steiner’s models and the buildings themselves reveal the intimate relationship between process and product that exists in his work. While the loss of the first Goetheanum came as a crushing blow to Steiner, its destruction and reconstruction offered him a unique opportunity to reconsider aspects of the design that may have been flawed in the first instance – a situation he embraced unequivocally. What images recurred in his work and why? How did his architecture evolve? This essay will demonstrate how paper and plasticine were utilised in a highly individualised manner by Steiner as a bridge between idea and artefact, to allow new architectural forms to rise from the ashes and produce one of the twentieth century’s most extraordinary buildings.

Insights into the biodiversity and social benchmarking components of the Northern Australian fire management and carbon abatement programmes

Much of northern Australia’s tropical savannas are subject to annual intense and extensive late dry season wildfires, much of this occurring on Aboriginal land. Based on the successful West Arnhem Land Fire Abatement (WALFA) model, which has resulted in significantly reduced greenhouse gas emissions, fire abatement programmes are planned for other significant regions of northern Australia. This study offers an introduction to the ideas behind a proposed environmental and social benchmarking project that aims to evaluate the potential benefits of expanding the fire abatement program in northern Australia, under the leadership of NAILSMA and its partners. Gaining a better understanding of the biodiversity, social and cultural outcomes of these fire abatement activities is an important component of demonstrating multiple benefits of these programmes. We emphasize the role of both biodiversity and cultural mapping to establish benchmarks and baseline states, with the involvement of Indigenous communities being a key element to optimize social and biodiversity benefits. Consultation with Traditional Owners and ranger groups to establish an agreed set of targets, indicators and sampling protocols and methodologies are critical component of this process. Examples of preliminary work to date are provided.

Effects of time since fire on birds : how informative are generalized fire response curves for conservation management?

Fire is both a widespread natural disturbance that affects the distribution of species and a tool that can be used to manage habitats for species. Knowledge of temporal changes in the occurrence of species after fire is essential for conservation management in fire-prone environments. Two key issues are: whether postfire responses of species are idiosyncratic or if multiple species show a limited number of similar responses; and whether such responses to time since fire can predict the occurrence of species across broad spatial scales. We examined the response of bird species to time since fire in semiarid shrubland in southeastern Australia using data from surveys at 499 sites representing a 100-year chronosequence. We used nonlinear regression to model the probability of occurrence of 30 species with time since fire in two vegetation types, and compared species' responses with generalized response shapes from the literature. The occurrence of 16 species was significantly influenced by time since fire: they displayed six main responses consistent with generalized response shapes. Of these 16 species, 15 occurred more frequently in mid- or later-successional vegetation (>20 years since fire), and only one species occurred more often in early succession (<5 years since fire). The models had reasonable predictive ability for eight species, some predictive ability for seven species, and were little better than random for one species. Bird species displayed a limited range of responses to time since fire; thus a small set of fire ages should allow the provision of habitat for most species. Postfire successional changes extend for decades and management of the age class distribution of vegetation will need to reflect this timescale. Response curves revealed important seral stages for species and highlighted the importance of mid- to late-successional vegetation (>20 years). Although time since fire clearly influences the distribution of numerous bird species, predictive models of the spatial distribution of species in fire-prone landscapes need to incorporate other factors in addition to time since fire.

A hybrid neural network model for noisy data regression

A hybrid neural network model, based on the fusion of fuzzy adaptive resonance theory (FA ART) and the general regression neural network (GRNN), is proposed in this paper. Both FA and the GRNN are incremental learning systems and are very fast in network training. The proposed hybrid model, denoted as GRNNFA, is able to retain these advantages and, at the same time, to reduce the computational requirements in calculating and storing information of the kernels. A clustering version of the GRNN is designed with data compression by FA for noise removal. An adaptive gradient-based kernel width optimization algorithm has also been devised. Convergence of the gradient descent algorithm can be accelerated by the geometric incremental growth of the updating factor. A series of experiments with four benchmark datasets have been conducted to assess and compare effectiveness of GRNNFA with other approaches. The GRNNFA model is also employed in a novel application task for predicting the evacuation time of patrons at typical karaoke centers in Hong Kong in the event of fire. The results positively demonstrate the applicability of GRNNFA in noisy data regression problems.

Vibration based damage identification of a scale-model steel frame structure subjected to bolt connection failures

Large-span steel frame structures prove to be an ideal choice for their speed of construction, relatively low cost, strength, durability and structural design flexibility. For this type of structure, the beam-column connections are critical for its structural integrity and overall stability. This is because a steel frame generally fails first at its connectors, due to the change in stress redistribution with adjacent members and material related failures, caused by various factors such as fire, seismic activity or material deterioration. Since particular attention is required at a steel frame’s connection points, this study explores the applicability of a comprehensive structural health monitoring (SHM) method to identify early damage and prolong the lifespan of connection points of steel frames. An impact hammer test was performed on a scale-model steel frame structure, recording its dynamic response to the hammer strike via an accelerometer. The testing procedure included an intact scenario and two damage scenarios by unfastening four bolt connections in an accumulating order. Based entirely on time-domain experimental data for its calibration, an Auto Regressive Average Exogenous (ARMAX) model is used to create a simple and accurate model for vibration simulation. The calibrated ARMAX model is then used to identify various bolt-connection related damage scenarios via R² value. The findings in this study suggest that the proposed time-domain approach is capable of identifying structural damage in a parsimonious manner and can be used as a quick or initial solution.

Why do some species have geographically varying responses to fire history?

A capacity to predict the effects of fire on biota is critical for conservation in fire-prone regions as it assists managers to anticipate the outcomes of different approaches to fire management. The task is complicated because species' responses to fire can vary geographically. This poses challenges, both for conceptual understanding of post-fire succession and fire management. We examine two hypotheses for why species may display geographically varying responses to fire. 1) Species' post-fire responses are driven by vegetation structure, but vegetation - fire relationships vary spatially (the 'dynamic vegetation' hypothesis). 2) Regional variation in ecological conditions leads species to select different post-fire ages as habitat (the 'dynamic habitat' hypothesis). Our case study uses data on lizards at 280 sites in a ~ 100 000 km2 region of south-eastern Australia. We compared the predictive capacity of models based on 1) habitat associations, with models based on 2) fire history and vegetation type, and 3) fire history alone, for four species of lizards. Habitat association models generally out-performed fire history models in terms of predictive capacity. For two species, habitat association models provided good discrimination capacity even though the species showed geographically varying post-fire responses. Our results support the dynamic vegetation hypothesis, that spatial variation in relationships between fire and vegetation structure results in regional variation in fauna-fire relationships. These observations explain how the widely recognised 'habitat accommodation' model of animal succession can be conceptually accurate yet predictively weak. © 2014 The Authors.

The effects of topographic variation and the fire regime on coarse woody debris: insights from a large wildfire

Coarse woody debris (CWD) is a common structural component of terrestrial ecosystems, and provides important habitat for biota. Fires modify the distribution of CWD, both spatially and temporally. Changes in fire regimes, such as those arising from prescribed burning and changing climatic conditions, make it critical to understand the response of this resource to fire. We created a conceptual model of the effects of fire on logs and dead trees in topographically diverse forests in which trees often survive severe fire. We then surveyed paired sites, in a damp gully and adjacent drier slope, ~3.5. years after a large wildfire in south-eastern Australia. Sites were stratified by fire severity (unburnt, understorey burnt and severely burnt), and fire history (burnt ≤3. years or ≥20. years prior to the wildfire). Both components of the fire regime influenced CWD availability in gullies. Severe wildfire and fire history ≤3. years reduced the volume of small logs (10-30. cm diameter) in gullies, while severe wildfire increased the number of large dead trees in gullies. CWD on slopes was not affected by fire severity or history at ~3.5. years post-fire. Log volumes on slopes may recover more quickly after wildfire through rapid collapse of branches and trees. Gullies generally supported more logs than slopes, but longer inter-fire intervals in gullies may allow fuel loads to accumulate and lead to comparatively larger fire impacts. Given that fire severity and fire interval are predicted to change in many fire-prone ecosystems in coming decades, this study highlights the importance of understanding the interacting effects of multiple components of the fire regime with landscape structure. In particular, variation in fire interval and fire severity in relation to topographic position will influence the pattern of accumulation of coarse woody debris across the landscape, and therefore the structure and quality of habitats for biota.

Evaluating the role of fire disturbance in structuring small reptile communities in temperate forests

Fire is an integral disturbance shaping forest community dynamics over large scales. However, understanding the relationship between fire induced habitat disturbance and biodiversity remain equivocal. Ecological theories including the intermediate disturbance hypothesis (IDH) and the habitat accommodation model (HAM) offer predictive frameworks that could explain faunal responses to fire disturbances. We used an 80 year post-fire chronosequence to investigate small reptile community responses to fires in temperate forests across 74 sites. First, we evaluated if changes in species richness, abundance and evenness post-fire followed trends of prior predictions, including the IDH. Second, using competing models of fine scale habitat elements we evaluated the specific ways which fire influenced small reptiles. Third, we evaluated support for the HAM by examining compositional changes of reptile community post-fire. Relative abundance was positively correlated to age post-fire while richness and evenness showed no associations. The abundance trend was as expected based on the prior prediction of sustained population increase post-disturbance, but the trend for richness contradicted the prediction of highest diversity at intermediate levels of disturbance (according to IDH). Abundance changes were driven mainly by changes in overstorey, ground layer, and shelter, while richness and evenness did not associate with any vegetation parameter. Community composition was not strongly correlated to age since fire, thus support for the HAM was weak. Overall, in this ecosystem, frequent fire disturbances can be detrimental to small reptiles. Future studies utilizing approaches based on species traits could enhance our understanding of biodiversity patterns post-disturbance.

Local environmental covariates are important for predicting fire history from tree stem diameters

In fire-prone landscapes, knowing when vegetation was last burnt is important for understanding how species respond to fire and to develop effective fire management strategies. However, fire history is often incomplete or non-existent. We developed a fire-age prediction model for two mallee woodland tree species in southern Australia. The models were based on stem diameters from ∼1172 individuals surveyed along 87 transects. Time since fire accounted for the greatest proportion of the explained variation in stem diameter for our two mallee tree species but variation in mean stem diameters was also influenced by local environmental factors. We illustrate a simple tool that enables time since fire to be predicted based on stem diameter and local covariates. We tested our model against new data but it performed poorly with respect to the mapped fire history. A combination of different covariate effects, variation in among-tree competition, including above- and below-ground competition, and unreliable fire history may have contributed to poor model performance. Understanding how the influence of covariates on stem diameter growth varies spatially is critical for determining the generality of models that predict time since fire. Models that were developed in one region may need to be independently verified before they can be reliably applied in new regions.