EVOLUTION, Issue 9 2007
Miguel Verdú
Mediterranean-type ecosystems are among the most remarkable plant biodiversity "hot spots" on the earth, and fire has traditionally been invoked as one of the evolutionary forces explaining this exceptional diversity. In these ecosystems, adult plants of some species are able to survive after fire (resprouters), whereas in other species fire kills the adults and populations are only maintained by an effective post-fire recruitment (seeders). Seeders tend to have shorter generation times than resprouters, particularly under short fire return intervals, thus potentially increasing their molecular evolutionary rates and, ultimately, their diversification. We explored whether seeder lineages actually have higher rates of molecular evolution and diversification than resprouters. Molecular evolutionary rates in different DNA regions were compared in 45 phylogenetically paired congeneric taxa from fire-prone Mediterranean-type ecosystems with contrasting seeder and resprouter life histories. Differential diversification was analyzed with both topological and chronological approaches in five genera (Banksia, Daviesia, Lachnaea, Leucadendron, and Thamnochortus) from two fire-prone regions (Australia and South Africa). We found that seeders had neither higher molecular rates nor higher diversification than resprouters. Such lack of differences in molecular rates between seeders and resprouters,which did not agree with theoretical predictions,may occur if (1) the timing of the switch from seeding to resprouting (or vice versa) occurs near the branch tip, so that most of the branch length evolves under the opposite life-history form; (2) resprouters suffer more somatic mutations and therefore counterbalancing the replication-induced mutations of seeders; and (3) the rate of mutations is not related to shorter generation times because plants do not undergo determinate germ-line replication. The absence of differential diversification is to be expected if seeders and resprouters do not differ from each other in their molecular evolutionary rate, which is the fuel for speciation. Although other factors such as the formation of isolated populations may trigger diversification, we can conclude that fire acting as a throttle for diversification is by no means the rule in fire-prone ecosystems [source]

FIGHTING FIRE WITH A BROKEN TEACUP: A COMPARATIVE ANALYSIS OF SOUTH AFRICA'S LAND-REDISTRIBUTION PROGRAM,

GEOGRAPHICAL REVIEW, Issue 3 2008
WILLIAM G. MOSELEY
ABSTRACT. Since the rise of its first democratically elected government in 1994, South Africa has sought to redress its highly inequitable land distribution through a series of land-reform programs. In this study we examine land-redistribution efforts in two of South Africa's provinces, the Western Cape and Limpopo. By analyzing a cross-section of projects in these two locales we develop a political ecology of stymied land-reform possibilities to explain the limited progress to date. Given South Africa's ambitious goal of redistributing 30 percent of its white-owned land by 2014 and the incremental and flawed nature of its redistribution program, we argue that the process is like trying to put out a fire with a broken teacup. Our results are based on interviews with policymakers, commercial farmers, and land-redistribution beneficiaries, as well as on an analysis of land-use change in Limpopo Province. [source]

Use of serial pig body weights for genetic evaluation of daily gain

JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2010
B. Zumbach
Summary This study examined the utility of serial weights from FIRE (Feed Intake Recording Equipment, Osborne Industries, Inc., Osborne, KS, USA) stations for an analysis of daily gain. Data included 884 132 body weight records from 3888 purebred Duroc pigs. Pigs entered the feeder station at age 77,149 days and left at age 95,184 days. A substantial number of records were abnormal, showing body weight close to 0 or up to twice the average weight. Plots of body weights for some animals indicated two parallel growth curves. Initial editing used a robust regression, which was a two-step procedure. In the first step, a quadratic growth curve was estimated assuming small or 0 weights for points far away from the curve; the process is iterative. In the second step, weights more than 1.5 SD from the estimated growth curve were treated as outliers. The retained body weight records (607 597) were averaged to create average daily weight (170 443) and then used to calculate daily gains (152 636). Additional editing steps included retaining only animals with ,50 body weight records and SD of the daily gain ,2 kg, followed by removing records outside 3 SD from the mean for given age, across all the animals , the resulting data set included 69 068 records of daily gain from 1921 animals. Daily gain based on daily, weekly and bi-weekly intervals was analysed using repeatability models. Heritability estimates were 0.04, 6 and 9%, respectively. The last two estimates correspond to heritability of 28% for a 12 week interval. For daily gain averaged weekly, the estimate of heritability obtained with a random regression model varied from 0.07 to 0.10. After extensive editing, body weight records from automatic feeding stations are useful for genetic analyses of daily gain from weekly or bi-weekly but not daily intervals. [source]

Strategic help in user interfaces for information retrieval

JOURNAL OF THE AMERICAN SOCIETY FOR INFORMATION SCIENCE AND TECHNOLOGY, Issue 5 2002
Giorgio Brajnik
Although no unified definition of the concept of search strategy in Information Retrieval (IR) exists so far, its importance is manifest: nonexpert users, directly interacting with an IR system, apply a limited portfolio of simple actions; they do not know how to react in critical situations; and they often do not even realize that their difficulties are due to strategic problems. A user interface to an IR system should therefore provide some strategic help, focusing user's attention on strategic issues and providing tools to generate better strategies. Because neither the user nor the system can autonomously solve the information problem, but they complement each other, we propose a collaborative coaching approach, in which the two partners cooperate: the user retains the control of the session and the system provides suggestions. The effectiveness of the approach is demonstrated by a conceptual analysis, a prototype knowledge-based system named FIRE, and its evaluation through informal laboratory experiments. [source]

TOMBS FOR THE DEAD, MONUMENTS TO ETERNITY: THE DELIBERATE DESTRUCTION OF MEGALITHIC GRAVES BY FIRE IN THE INTERIOR HIGHLANDS OF IBERIA (SORIA PROVINCE, SPAIN)

OXFORD JOURNAL OF ARCHAEOLOGY, Issue 3 2010
MANUEL A. ROJO-GUERRA
Summary An interpretation of the features surrounding the complex and deliberate closure ritual in several collective Middle Neolithic tombs of the Ambrona Valley (Soria) is offered, where fire and quicklime played a major role in the rituals. The problems involved in the excavation and the understanding of this complex burial evidence are examined. The roles they might have played in the context of the important social and economic transformations of the local Neolithic groups around the end of the fourth millennium cal BC are also analysed. It is argued that the burial rituals tried to reinforce group solidarity at a time when the community was beginning to fragment, as the economic systems began to yield a surplus production whose management would have altered political structures. [source]

EMPIRICAL IMPACT OF PUBLIC INFRASTRUCTURE ON THE JAPANESE ECONOMY,

THE JAPANESE ECONOMIC REVIEW, Issue 4 2008
CHRISTOPHER N. ANNALA
We study the impact of public capital investment on individual sectors of the Japanese economy using time-series data for the period of 1970,1998. We employ a production function approach and also estimate a dynamic VAR/ECM model. We find significant differences in the employment effects, output effects and private investment effects across sectors. Public capital investment has a positive effect on employment in the finance, insurance and real estate (FIRE), manufacturing, construction and utilities sectors; on private investment in the FIRE, agriculture, transportation, trade and services sectors; and on output in the mining, FIRE, trade and manufacturing sectors. [source]

PLACE, PRINT AND MIRACLE: FORLÍ'S MADONNA OF THE FIRE AS FUNCTIONAL SITE

ART HISTORY, Issue 3 2008
LISA PON
The Madonna of the Fire of Forlì is an early woodcut that miraculously survived a fire in 1428, and still resides in the cathedral of Forlì, a city southeast of Bologna. This miracle removed the woodcut from the traffic in images crossing geographic and chronological boundaries in which other early modern prints participated. Since 1428 it has acted instead as a functional site, bound to a single place and able to galvanize disparate local elements into a communal sense of emplacement. This essay explores both that ability to generate a local identity, as well as the Madonna of the Fire's status as a miraculous object. For the transformation of the Madonna of the Fire from quotidian devotional print to miraculous cult icon also activated its ability to work as a functional site by charging overlapping material, geographic and discursive loci with communal significance. [source]

THE NATURE OF FIRE AND ITS COMPLICATIONS: THEOPHRASTUS' DE IGNE 1,10

BULLETIN OF THE INSTITUTE OF CLASSICAL STUDIES, Issue 1 2010
MARLEIN VAN RAALTE
This article offers a running commentary on De igne 1,10 (with text and translation). The way in which Theophrastus sets out to ascribe to the simple body of fire characteristics of terrestrial, burning fire, and only gradually dismisses his focus on fire (and its alter ego of heat) as a principle seems to indicate an early stage of his thought. On the other hand, a formal analysis of the text shows that the argument bears an unmistakably Theophrastean stamp. Finally it is argued that it cannot be inferred from De igne that Theophrastus adhered to the Aristotelian concept of aithêr, and that it is also very unlikely that he did so. The relevant passages from Theophrastus' botanical treatises and Metaphysics confirm this picture. Even the quite explicit testimonies from Philoponus and Julian seem to allow of an interpretation that does not involve Theophrastus having adopted this Aristotelian concept. [source]

Febrile infection,related epilepsy syndrome (FIRES): A nonencephalitic encephalopathy in childhood

EPILEPSIA, Issue 7 2010
Andreas Van Baalen
Summary Encephalitis is generally presumed, even when seizures follow banal febrile infection, and pathogen detection in cerebrospinal fluid fails. This retrospective multicenter case series reports on 22 previously healthy children aged 3,15 years (median 6.5 years) with prolonged or recurrent seizures occurring 2,14 days (median 5 days) after fever onset (19 children with respiratory or nonspecific infections). Cerebrospinal fluid studies revealed 2,42 cells/,l (median 5 cells/,l) and no pathogens. Electroencephalography showed diffuse slowing or multifocal discharges. Neuroimaging demonstrated normal findings in 10 children. Brain biopsies were performed in seven children showing gliosis but no inflammation. Anesthetic barbiturates were used in 14 children with refractory status epilepticus, and immunotherapy in 9. Two children died, eight remained in a state of impaired consciousness, eight developed therapy-refractory epilepsies, two had behavioral disturbances, and two recovered. The lack of evidence for encephalitis suggests another infection-related pathogenesis of this disastrous epileptic encephalopathy. Therefore, we propose the term "febrile infection,related epilepsy syndrome" (FIRES). [source]

Death Rides the Forest: Perceptions of Fire, Land Use, and Ecological Restoration of Western Forests

CONSERVATION BIOLOGY, Issue 4 2004
J. BOONE KAUFFMAN
fuego prescrito; incendios catastróficos; incendios en áreas silvestres; incendios no controlados; reducción de riesgo de combustible; restauración de bosques; tala de bosques Abstract:,Large wild fires occurring in forests, grasslands, and chaparral in the last few years have aroused much public concern. Many have described these events as "catastrophes" that must be prevented through aggressive increases in forest thinning. Yet the real catastrophes are not the fires themselves but those land uses, in concert with fire-suppression policies that have resulted in dramatic alterations to ecosystem structure and composition. The first step in the restoration of biological diversity (forest health) of western landscapes must be to implement changes in those factors that have caused degradation or are preventing recovery. This includes changes in policies and practices that have resulted in the current state of wildland ecosystems. Restoration entails much more than simple structural modifications achieved though mechanical means. Restoration should be undertaken at landscape scales and must allow for the occurrence of dominant ecosystem processes, such as the natural fire regimes achieved through natural and/or prescribed fires at appropriate temporal and spatial scales. Resumen:,En años recientes, grandes incendios en bosques, pastizales y chaparrales han causado bastante preocupación en la opinión pública. Muchos han descrito estos eventos como "catástrofes" que deben ser prevenidas mediante incrementos agresivos en la tala de bosques. Pero los incendios mismos no son las verdaderas catástrofes, sino los usos del suelo en conjunto con políticas de supresión de fuego que han resultado en alteraciones dramáticas de la estructura y composición de ecosistemas. El primer paso en la restauración de la diversidad biológica (salud del bosque) en paisajes occidentales debe ser la implementación de cambios en los factores que causaron la degradación o que están impidiendo la recuperación. Esto incluye cambios en políticas y prácticas que han resultado en el estado actual de ecosistemas en áreas silvestres. La restauración implica mucho más que simples modificaciones estructurales obtenidas mediante medios mecánicos. La restauración debe llevarse a cabo a nivel de paisaje y debe permitir que ocurrencia de procesos ecológicos dominantes (por ejemplo, regímenes de incendios naturales logrados mediante incendios naturales y/o prescritos en escalas temporales y espaciales apropiadas). [source]

Capitalism and Climate Change: Can the Invisible Hand Adjust the Natural Thermostat?

DEVELOPMENT AND CHANGE, Issue 6 2009
Servaas Storm
Some say the world will end in fire, Some say in ice. From what I've tasted of desire I hold with those who favor fire. But if it had to perish twice, I think I know enough of hate To say that for destruction ice Is also great And would suffice. (Robert Frost, ,Fire and Ice', New Hampshire,1923) ABSTRACT Can climate change be stopped while fossil fuel capitalism remains the dominant system? What has to be done and what has to change to avoid the worst-case consequences of global warming? These questions are debated in the six contributions which follow. This introduction to the debate sets the stage and puts the often widely diverging views in context, distinguishing two axes of debate. The first axis (,market vs. regulation') measures faith in the invisible hand to adjust the natural thermostat. The second axis expresses differences in views on the efficiency and equity implications of climate action. While the contributions do differ along these axes, most authors agree that capitalism's institutions need to be drastically reformed and made fundamentally more equitable. This means a much broader agenda for the climate movement (going beyond carbon trading and technocratic discussion of mitigation options). What is needed for climate stability is a systemic transformation based on growth scepticism, a planned transition to a non-fossil fuel economy, democratic reform, climate justice, and changed global knowledge and corporate and financial power structures. [source]

The role of environmental gradients in non-native plant invasion into burnt areas of Yosemite National Park, California

DIVERSITY AND DISTRIBUTIONS, Issue 2 2006
Rob Klinger
ABSTRACT Fire is known to facilitate the invasion of many non-native plant species, but how invasion into burnt areas varies along environmental gradients is not well-understood. We used two pre-existing data sets to analyse patterns of invasion by non-native plant species into burnt areas along gradients of topography, soil and vegetation structure in Yosemite National Park, California, USA. A total of 46 non-native species (all herbaceous) were recorded in the two data sets. They occurred in all seven of the major plant formations in the park, but were least common in subalpine and upper montane conifer forests. There was no significant difference in species richness or cover of non-natives between burnt and unburnt areas for either data set, and environmental gradients had a stronger effect on patterns of non-native species distribution, abundance and species composition than burning. Cover and species richness of non-natives had significant positive correlations with slope (steepness) and herbaceous cover, while species richness had significant negative correlations with elevation, the number of years post-burn, and cover of woody vegetation. Non-native species comprised a relatively minor component of the vegetation in both burnt and unburnt areas in Yosemite (percentage species = 4%, mean cover < 6.0%), and those species that did occur in burnt areas tended not to persist over time. The results indicate that in many western montane ecosystems, fire alone will not necessarily result in increased rates of invasion into burnt areas. However, it would be premature to conclude that non-native species could not affect post-fire succession patterns in these systems. Short fire-return intervals and high fire severity coupled with increased propagule pressure from areas used heavily by humans could still lead to high rates of invasion, establishment and spread even in highly protected areas such as Yosemite. [source]

Comparative seed ecology of the endangered shrub, Pimelea spicata and a threatening weed, Bridal Creeper: Smoke, heat and other fire-related germination cues

ECOLOGICAL MANAGEMENT & RESTORATION, Issue 1 2003
Anthony J. Willis
SummaryPimelea spicata R. Br. is a nationally listed endangered Australian shrub threatened with extinction by habitat fragmentation and environmental weed invasion. Bridal Creeper (Asparagus asparagoides L. W. Wight) is the primary weed threat to the largest remaining populations of P. spicata in the Cumberland Plain. Fire, as part of an integrated pest management program, offers the potential to stimulate P. spicata populations while controlling Bridal Creeper. It is important, therefore, to understand how the components of fire affect the germination and growth of both species. Using laboratory experiments we investigated the effects of smoke, heat, ash and/or light on the germination of P. spicata and Bridal Creeper. We found a significant promotive effect of smoke and indication of an inhibitory heat shock (90°C for 10 min) effect on the germination of P. spicata seeds. The response of Bridal Creeper seeds to the same factors was complex; while the results of one experiment suggested an inhibitory effect of smoke and a promotive effect of heat, subsequent trials were contradictory, implying that Bridal Creeper, like many weeds, is able to germinate under a wide range of environmental conditions. Other experiments investigated the optimal germination temperature and innate dormancy of P. spicata in the absence of fire-related germination cues. Of the incubation temperatures investigated, the optimal diurnally fluctuating regime for P. spicata germinations was 10°C and 20°C in the night and day, respectively. The innate dormancy of freshly produced seeds disappeared after 3 months. In contrast to Bridal Creeper, we found a persistent germinable seed bank of about 97 P. spicata seeds/m2 located in the top 5 cm of the soil profile. While fire alone is unlikely to kill Bridal Creeper plants, fire may help to manage local infestations of the weed by limiting germination and providing opportunity for herbicide treatment of regrowth. [source]

Fire and the Miocene expansion of C4 grasslands

ECOLOGY LETTERS, Issue 7 2005
Jon E. Keeley
Abstract C4 photosynthesis had a mid-Tertiary origin that was tied to declining atmospheric CO2, but C4 -dominated grasslands did not appear until late Tertiary. According to the ,CO2 -threshold' model, these C4 grasslands owe their origin to a further late Miocene decline in CO2 that gave C4 grasses a photosynthetic advantage. This model is most appropriate for explaining replacement of C3 grasslands by C4 grasslands, however, fossil evidence shows C4 grasslands replaced woodlands. An additional weakness in the threshold model is that recent estimates do not support a late Miocene drop in pCO2. We hypothesize that late Miocene climate changes created a fire climate capable of replacing woodlands with C4 grasslands. Critical elements were seasonality that sustained high biomass production part of year, followed by a dry season that greatly reduced fuel moisture, coupled with a monsoon climate that generated abundant lightning-igniting fires. As woodlands became more open from burning, the high light conditions favoured C4 grasses over C3 grasses, and in a feedback process, the elevated productivity of C4 grasses increased highly combustible fuel loads that further increased fire activity. This hypothesis is supported by paleosol data that indicate the late Miocene expansion of C4 grasslands was the result of grassland expansion into more mesic environments and by charcoal sediment profiles that parallel the late Miocene expansion of C4 grasslands. Many contemporary C4 grasslands are fire dependent and are invaded by woodlands upon cessation of burning. Thus, we maintain that the factors driving the late Miocene expansion of C4 were the same as those responsible for maintenance of C4 grasslands today. [source]

Probabilistic risk modeling at the wildland urban interface: the 2003 Cedar Fire

ENVIRONMETRICS, Issue 6 2009
D. R. Brillinger
Abstract The October 2003 Cedar Fire in San Diego County was a tragedy involving 15 deaths, the burning of some 280,000,acres of land, the destruction of approximately 2227 homes, and costs of suppression near $30 million. It was the largest fire in California history. The data associated with the fire, however, do provide an opportunity to carry out probabilistic risk modeling of a wildland-urban interface (WUI) event. WUI's exist where humans and their development interface with wildland fuel. As home building expands from urban areas to nearby forest areas, these homes become more likely to burn. Wildfires are an exceedingly complex phenomenon with uncertainty and unpredictability abounding, hence a statistical approach to gaining insight appears useful. In this research, spatial stochastic models are developed. These relate risk probabilities and losses measures to a variety of available explanatory quantities. There is a consideration of economic aspects and a discussion of the difficulties that arose in developing the data and of carrying out the analyses. Purposes of the work include highlighting a statistical method, developing variates associated with a destruction probability and employing the fitted risk probability to estimate future and possible losses. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Changes in organic matter, nitrogen, phosphorus and cations in soil as a result of fire and water erosion in a Mediterranean landscape

EUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2000
E. Gimeno-García
Summary Fire affects large parts of the dry Mediterranean shrubland, resulting in erosion and losses of plant nutrients. We have attempted to measure these effects experimentally on a calcareous hillside representative of such shrubland. Experimental fires were made on plots (4 m × 20 m) in which the fuel was controlled to obtain two different fire intensities giving means of soil surface temperature of 439°C and 232°C with temperatures exceeding 100°C lasting for 36 min and 17 min. The immediate and subsequent changes induced by fire on the soil's organic matter content and other soil chemical properties were evaluated, together with the impact of water erosion. Seven erosive rain events, which occurred after the experimental fires (from August 1995 to December 1996), were selected, and on them runoff and sediment produced from each plot were measured. The sediments collected were weighed and analysed. Taking into account the variations induced by fire on the soil properties and their losses by water erosion, estimates of the net inputs and outputs of the soil system were made. Results show that the greatest losses of both soil and nutrients took place in the 4 months immediately after the fire. Plots affected by the most intense fire showed greater losses of soil (4077 kg ha,1) than those with moderate fire intensity (3280 kg ha,1). The unburned plots produced the least sediment (72.8 kg ha,1). Organic matter and nutrient losses by water erosion were related to the degree of fire intensity. However, the largest losses of N-NH4+ and N-NO3, by water erosion corresponded to the moderate fire (8.1 and 7.5 mg N m,2, respectively). [source]

An evaluation of the self-heating hazards of cerium(IV) nitrated treated towels using differential scanning calorimetry and thermogravimetric analysis

FIRE AND MATERIALS, Issue 6 2007
J. R. Hartman
Abstract This study measured the Arrhenius kinetic parameters and heat of reaction using thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) for the combustion of untreated towels and towels treated with cerium(IV) nitrate. These parameters were used to calculate the self-heating parameters, M and P (Self-heating: Evaluating and Controlling the Hazard. Her Majesty's Stationery Office: London, 1984) and the critical pile sizes of the towels at several temperatures. The results from the TGA/DSC experiments support the conclusions by Beyler et al. (Fire and Materials 2005; 30:223,240) that the cerium(IV) nitrate treatment of towels significantly enhances the ignitability of the towels but that self-heating is not a hazard for normal temperature storage scenarios other than bulk storage. It was found that the kinetic reaction data measured by TGA and DSC are only useful for predicting the specific reaction hazard for materials stored above 100°C. A comparison of the self-heating parameters measured by oven and kinetic reaction data methods for a number of materials suggests that the kinetic reaction data overestimate the critical pile size at temperatures below 100°C. In addition, it was found that the kinetic reaction data measured by TGA can be used to determine the relative self-heating hazards for modified materials. TGA testing with towels saturated with a 0.5 N solution of cerium(IV) nitrate (Ce(NO3)4) in a 2.0 N solution of nitric acid, a 2.0 N solution of sodium nitrate in 2.0 N nitric acid and simple 2.0 N nitric acid, showed that the sodium nitrate and nitric acid treated samples reacted at the same temperatures as the untreated towels, while cerium(IV) nitrate markedly reduced the reaction temperature. These tests clearly point to the importance of the cerium(IV) ion as an oxidizing agent. Thus, the TGA testing provided in a matter of days, insights that would have required months of oven testing. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Mechanisms and modes for ignition of low-voltage, PVC-insulated electrotechnical products

FIRE AND MATERIALS, Issue 2 2006
Vytenis BabrauskasArticle first published online: 1 AUG 200
Abstract PVC is the most common insulation material used for wiring in low-voltage (LV) service. ,Low-voltage', in the context of this paper, is taken to be 120,240 VAC. The electrotechnical products considered include insulated wires, cables and cords, and also appurtenant termination devices, e.g. male plugs or female taps. Well-known factors leading to the ignition of PVC-insulated wiring and related products include: (a) manufacturing defects; (b) grossly excessive current; (c) over-insulation, sometimes augmented by overcurrent; (d) localized heating due to strand breakage; (e) localized heating due to mechanical strand severing by staples or nails; and (f) localized heating due to failed terminations. Other failure modes are known but have received only limited study. These include (i) excessive force and creep; (ii) chemical interaction effects; and (iii) breakdown under voltage surge conditions. Additional research is needed in these areas. The proximate cause of ignition involved with many of the above mechanisms is arc tracking (arcing across a carbonized path). In turn, it is shown that PVC is especially susceptible to becoming charred, it requiring only approximately 160°C for the material to become semiconducting during short-term exposure (around 10 h), while longer-term exposure (around 1 month) may cause failures at temperatures as low as 110°C. Some limited data exist which suggest that standard UL and IEC temperature classifications are unduly optimistic, as applied to PVC. Fire can originate if wiring or equipment cannot withstand a powerline surge. Mains-connected electrical appliances need to be designed to resist 6000 V surge voltages, even though this is not mandated in most of the current UL and IEC standards. Data are presented showing that the IEC 60112 wet-tracking test gives especially misleading results for PVC and should be improved or abrogated. Copyright © 2005 John Wiley & Sons, Ltd. [source]

A model to predict fire resistance of non-load bearing wood-stud walls

FIRE AND MATERIALS, Issue 1 2003
H. Takeda
Abstract The author has developed a series of computer models to predict the fire resistance of wood-framed walls and floors. The models utilize two-dimensional heat-conduction equations and thermo-physical property data to describe heat transfer through the assemblies. The model for wall assemblies WALL2D, the basic version of the wall model, has already been published in Fire and Materials. Recently, WALL2D has been extended to WALL2DN to analyse heat transfer through insulated walls and walls that experience openings at the joints between adjacent sheets of gypsum board. Since gypsum board shrinks at high temperatures, the joints between adjacent sheets of gypsum board open. Hot fire gases, thereby, enter the openings and heat the edge of the gypsum board and wood studs. The new model WALL2DN simulates the joint opening and describes the resultant effect of openings. The model also calculates heat transfer through insulation in the stud cavity and depicts the effect of insulation on the fire resistance of non-load bearing wall assemblies. Insulation selected in WALL2DN is glass-fibre insulation, rock-fibre insulation, polystyrene foam and polyurethane foam. When walls are exposed to fire, the insulation in the cavity shrinks (and/or melts) and an empty space appears at the interface between insulation and gypsum board. The model simulates this shrinking behaviour of insulation in the cavity. Finally, the model was validated by comparing the predicted results to those from full-scale standard fire-endurance tests. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Fire, flow and dynamic equilibrium in stream macroinvertebrate communities

FRESHWATER BIOLOGY, Issue 2 2010
ROBERT S. ARKLE
Summary 1. The complex effects of disturbances on ecological communities can be further complicated by subsequent perturbations within an ecosystem. We investigated how wildfire interacts with annual variations in peak streamflow to affect the stability of stream macroinvertebrate communities in a central Idaho wilderness, USA. We conducted a 4-year retrospective analysis of unburned (n = 7) and burned (n = 6) catchments, using changes in reflectance values (,NBR) from satellite imagery to quantify the percentage of each catchment's riparian and upland vegetation that burned at high and low severity. 2. For this wildland fire complex, increasing riparian burn severity and extent were associated with greater year-to-year variation, rather than a perennial increase, in sediment loads, organic debris, large woody debris (LWD) and undercut bank structure. Temporal changes in these variables were correlated with yearly peak flow in burned catchments but not in unburned reference catchments, indicating that an interaction between fire and flow can result in decreased habitat stability in burned catchments. 3. Streams in more severely burned catchments exhibited increasingly dynamic macroinvertebrate communities and did not show increased similarity to reference streams over time. Annual variability in macroinvertebrates was attributed, predominantly, to the changing influence of sediment, LWD, riparian cover and organic debris, as quantities of these habitat components fluctuated annually depending on burn severity and annual peak streamflows. 4. These analyses suggest that interactions among fire, flow and stream habitat may increase inter-annual habitat variability and macroinvertebrate community dynamics for a duration approaching the length of the historic fire return interval of the study area. [source]

An Exchange for All Things?

GEOGRAPHICAL RESEARCH, Issue 1 2001
An Inquiry into the Scholarship of Fire
Fire was once considered a founding element and an informing principle for analysis of the world. Today it is neither. Its study resides primarily in those countries that have both public lands, which hold fire, and scientific institutions, with which to study it. In particular, forestry has long claimed fire as a speciality and continues to harbour the most practical experience regarding it. In fact, fire may deserve better, and can give more. A case, not entirely whimsical, can be made for a programme of ,fire studies' that could span the many forms of scholarship that share an interest in humanity's species monopoly over fire's manipulation. [source]

Fire in the American South: Vegetation Impacts, History, and Climatic Relations

GEOGRAPHY COMPASS (ELECTRONIC), Issue 8 2010
Charles W. Lafon
Fire plays a key role in many ecosystems of the southeastern U.S. Longleaf pine (Pinus palustris) and Table Mountain pine-pitch pine (P. pungens,P. rigida) forests along with other ecosystems , including oak (Quercus) forests, grasslands, and spruce-fir (Picea-Abies) forests , illustrate the range of fire effects and plant persistence strategies in the American South. Fire history research reveals that fires and fire-associated vegetation were common before the fire exclusion of the past century. Both lightning and anthropogenic ignitions (caused by American Indians or European settlers) contributed to burning, but their relative importance is debated. The humid climate constrains burning, especially by lightning-ignited fires, which often occur during moist conditions. Studies of fire climatology indicate the importance of dry conditions (e.g. drought years and relatively dry areas) for widespread burning in this humid region. Landscape fragmentation also influences burning. In the past some fires also likely grew much larger than today because they were unimpeded by roads, farms, and other barriers. [source]

Postfire response of North American boreal forest net primary productivity analyzed with satellite observations

GLOBAL CHANGE BIOLOGY, Issue 8 2003
Jeffrey A. Hicke
Abstract Fire is a major disturbance in the boreal forest, and has been shown to release significant amounts of carbon (C) to the atmosphere through combustion. However, less is known about the effects on ecosystems following fire, which include reduced productivity and changes in decomposition in the decade immediately following the disturbance. In this study, we assessed the impact of fire on net primary productivity (NPP) in the North American boreal forest using a 17-year record of satellite NDVI observations at 8- km spatial resolution together with a light-use efficiency model. We identified 61 fire scars in the satellite observations using digitized fire burn perimeters from a database of large fires. We studied the postfire response of NPP by analyzing the most impacted pixel within each burned area. NPP decreased in the year following the fire by 60,260 g C m,2 yr,1 (30,80%). By comparing pre- and postfire observations, we estimated a mean NPP recovery period for boreal forests of about 9 years, with substantial variability among fires. We incorporated this behavior into a carbon cycle model simulation to demonstrate these effects on net ecosystem production. The disturbance resulted in a release of C to the atmosphere during the first 8 years, followed by a small, but long-lived, sink lasting 150 years. Postfire net emissions were three times as large as from a model run without changing NPP. However, only small differences in the C cycle occurred between runs after 8 years due to the rapid recovery of NPP. We conclude by discussing the effects of fire on the long-term continental trends in satellite NDVI observed across boreal North America during the 1980s and 1990s. [source]

Post-wildfire changes in suspended sediment rating curves: Sabino Canyon, Arizona

HYDROLOGICAL PROCESSES, Issue 11 2007
Sharon L. E. Desilets
Abstract Wildfire has been shown to increase erosion by several orders of magnitude, but knowledge regarding short-term variations in post-fire sediment transport processes has been lacking. We present a detailed analysis of the immediate post-fire sediment dynamics in a semi-arid basin in the southwestern USA based on suspended sediment rating curves. During June and July 2003, the Aspen Fire in the Coronado National Forest of southern Arizona burned an area of 343 km2. Surface water samples were collected in an affected watershed using an event-based sampling strategy. Sediment rating parameters were determined for individual storm events during the first 18 months after the fire. The highest sediment concentrations were observed immediately after the fire. Through the two subsequent monsoon seasons there was a progressive change in rating parameters related to the preferential removal of fine to coarse sediment. During the corresponding winter seasons, there was a lower supply of sediment from the hillslopes, resulting in a time-invariant set of sediment rating parameters. A sediment mass-balance model corroborated the physical interpretations. The temporal variability in the sediment rating parameters demonstrates the importance of storm-based sampling in areas with intense monsoon activity to characterize post-fire sediment transport accurately. In particular, recovery of rating parameters depends on the number of high-intensity rainstorms. These findings can be used to constrain rapid assessment fire-response models for planning mitigation activities. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Assessing burn severity and comparing soil water repellency, Hayman Fire, Colorado

HYDROLOGICAL PROCESSES, Issue 1 2006
Sarah A. Lewis
Abstract An important element of evaluating a large wildfire is to assess its effects on the soil in order to predict the potential watershed response. After the 55 000 ha Hayman Fire on the Colorado Front Range, 24 soil and vegetation variables were measured to determine the key variables that could be used for a rapid field assessment of burn severity. The percentage of exposed mineral soil and litter cover proved to be the best predictors of burn severity in this environment. Two burn severity classifications, one from a statistical classification tree and the other a Burned Area Emergency Response (BAER) burn severity map, were compared with measured ,ground truth' burn severity at 183 plots and were 56% and 69% accurate, respectively. This study also compared water repellency measurements made with the water drop penetration time (WDPT) test and a mini-disk infiltrometer (MDI) test. At the soil surface, the moderate and highly burned sites had the strongest water repellency, yet were not significantly different from each other. Areas burned at moderate severity had 1·5 times more plots that were strongly water repellent at the surface than the areas burned at high severity. However, the high severity plots most likely had a deeper water repellent layer that was not detected with our surface tests. The WDPT and MDI values had an overall correlation of r = ,0·64(p < 0·0001) and appeared to be compatible methods for assessing soil water repellency in the field. Both tests represent point measurements of a soil characteristic that has large spatial variability; hence, results from both tests reflect that variability, accounting for much of the remaining variance. The MDI is easier to use, takes about 1 min to assess a strongly water repellent soil and provides two indicators of water repellency: the time to start of infiltration and a relative infiltration rate. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Wind, Fire and Water: Renewable Energy and Birds Proceedings of the British Ornithologists' Union Annual Spring Conference 2005 University of Leicester, 1,3 April 2005

IBIS, Issue 2006
ROWENA H. W. LANGSTON Guest Editor
No abstract is available for this article. [source]

Opening address to Wind, Fire and Water: Renewable Energy and Birds

IBIS, Issue 2006
ELLIOT MORLEY
First page of article [source]

Fire and species range in Mediterranean landscapes: an experimental comparison of seed and seedling performance among Centaurea taxa

JOURNAL OF BIOGEOGRAPHY, Issue 1 2002
Miquel Riba
Aim Fire is a major disturbance event in Mediterranean landscapes. In this paper, we experimentally assess the effects of fire and post-fire conditions on seed germination and establishment of twenty Centaurea taxa to test whether differences among taxa are associated with range size. Methods The taxa (species and subspecies) considered were classified as rare and widespread according to their `area of occupancy' in the Mediterranean coast of Spain and France. In a first experiment, we analyse the effects of heat-shock (particularly, room temperature, 70 and 110 °C) on percentage germination and speed of germination (T50). In a second experiment, we analyse the effects of post-fire conditions (shading and soil type: burned/unburned) on seed germination and establishment ability. Results Temperatures over 120 °C resulted in 100% mortality, while temperatures in the range of those expected to be found in the first centimetres down the soil profile during a wildfire (70,110 °C) had no effect on seed germination. Differences in germination percentage and T50 among taxa were not related to rarity. In the post-fire conditions experiment, decreased radiation (shading) increased percentage germination and T50 in most taxa, while burned soil decreased germination in some of them. The effects of post-fire conditions on seedling growth (number of leaves and leaf size) were also different among taxa, but such differences were not related to rarity. However, rarity was associated with low establishment ability, as rare taxa tended to show smaller seedling size and higher mortality rates under the whole range of conditions tested. Main conclusions The results obtained indicate that fire has a negative effect upon the survival of populations in all the taxa considered, and that rare-common differences in germination and seedling establishment are not directly related to disturbance by fire. As far as interspecific differences in range size are concerned, other factors, either alone or in combination with a low regeneration ability after fire, need to be explored further. [source]

Herbaceous phytomass and nutrient concentrations of four grass species in Sudanian savanna woodland subjected to recurrent early fire

AFRICAN JOURNAL OF ECOLOGY, Issue 4 2009
Patrice Savadogo
Abstract Fire is an integral ecological factor in African savanna ecosystems, but its effects on savanna productivity are highly variable and less understood. We conducted a field experiment to quantify changes in herbaceous phytomass and nutrient composition in a Sudanian savanna woodland subjected to annual early fire from 1993 to 2004. Fire effects were also assessed on two perennial and two annual grass species during the following growing season. Early fire significantly reduced above-ground phytomass of the studied species (P = 0.03), their crude protein (P = 0.022), neutral detergent insoluble crude protein (P = 0.016) and concentrations of Ca, Fe and Mn (P < 0.05). Perennial grasses had higher above-ground phytomass but lower total crude protein and fat than annual grasses. Nonstructural carbohydrates tended to be higher for annuals, while fibre and lignin contents were high for perennials. Except Na and Fe, the concentration of mineral elements varied between species. Fire did not affect measures of digestibility and metabolizable energy, but its effect differed significantly among species. In conclusion, the results illustrate that long-term frequent fire will counterbalance the short-term increase in soil fertility and plant nutrient concentrations claimed to be accrued from single or less frequent fire. Résumé Le feu est un facteur écologique à part entière dans les écosystèmes de savane africaine, mais ses effets sur la productivité de la savane sont très variables et mal compris. Nous avons réalisé une expérience de terrain pour quantifier des changements de biomasse herbacée et de composition des nutriments dans une forêt de savane soudanienne sujette à des feux précoces annuels, entre 1993 et 2004. Les effets des feux ont aussi étéévalués sur deux espèces d'herbes pérennes et sur deux espèces annuelles au cours de la saison de croissance suivante. Le feu précoce réduit significativement la biomasse végétale aérienne des espèces étudiées (P = 0.03), leurs matières azotées (P = 0.022), les protéines brutes insolubles au détergent neutre (P = 0.016) et les concentrations de Ca, Fe et Mn (P < 0.05). Les herbes pérennes avaient une plus grande biomasse aérienne mais un taux plus faible de matières azotées totales et de lipides que les herbes annuelles. Les hydrates de carbone non structurés avaient tendance àêtre plus élevés pour les herbes annuelles, alors que les contenus en fibres et en lignine étaient élevés chez les pérennes. À l'exception du Na et du Fe, la concentration des minéraux variait selon les espèces. Le feu n'affectait pas les mesures de digestibilité et d'énergie métabolisable mais son effet différait significativement selon les espèces. En conclusion, les résultats illustrent que des feux fréquents utilisés à long terme vont contrebalancer l'augmentation à court terme de la fertilité du sol et les concentrations de nutriments dans les plantes, dont on dit qu'elles sont accrues par des feux uniques ou moins fréquents. [source]

Rescue robots for mudslides: A descriptive study of the 2005 La Conchita mudslide response

JOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 1-2 2008
Robin R. Murphy
The Center for Robot-Assisted Search and Rescue (CRASAR) assisted the Ventura County Fire Rescue Department with the January 2005 La Conchita, California, mudslide response. CRASAR provided commercially available urban search and rescue robots and expert operators which were deployed twice into damaged structures. The waterproof robots were able to tolerate wet conditions but proved unable to handle the densely packed rubble, vegetation, and soil and failed within two and four minutes, respectively on their two deployments. Informal interviews were conducted with responders as well. The experience forms a descriptive study of what mudslide responses are like, what tasks robots are needed for, how the rescue robots performed, and how responders viewed the robots. Our observations are captured in fourteen findings on robot performance (3), domain characteristics of mudslides (8), and general rescue robot design issues (3). These findings are expected to be of interest to robot designers, software developers, and the human-robot interaction communities. The experience at La Conchita illustrates that terrain understanding, critical for both robot design and for control, remains an important open research question for rescue robotics. © 2008 Wiley Periodicals, Inc. [source]