scholarly journals Performance of Ultra Shallow Floor Beams (USFB) exposed to standard and natural fires

2021 ◽  
Vol 38 ◽  
pp. 102192
Author(s):  
Naveed Alam ◽  
Chrysanthos Maraveas ◽  
Konstantinos Daniel Tsavdaridis ◽  
Ali Nadjai
Keyword(s):  
Natural Fires

scholarly journals Charcoal in soils of the Allerød-Younger Dryas transition were the result of natural fires and not necessarily the effect of an extra-terrestrial impact

2008 ◽  
Vol 87 (4) ◽  
pp. 359-361 ◽  
Author(s):  
T. van der Hammen ◽  
B. van Geel
Keyword(s):  
North America ◽  
Large Scale ◽  
Sand Dunes ◽  
Younger Dryas ◽  
Natural Fires ◽  
Water Tables ◽  
Pine Trees ◽  
Climate Cooling ◽  
Fossil Records ◽  
Terrestrial Material

AbstractDuring the warm Bølling-Allerød interstadial, tree species migrated from their refugia in southern Europe northwards into the area within the present temperate climatic zone. It is evident from high levels of charcoal in fossil records in this region that, especially during the later part of the Bølling-Allerød interstadial, many fires occurred. The start of the Younger Dryas was characterised by rapid and intense cooling and rising water tables, with catastrophic effects on the vegetation. Thermophilous pine trees could not survive the cold Younger Dryas climate. Dead wood provided an abundant source of fuel for intense, large-scale fires seen in many records as a concentration of charcoal particles in so-called ’Usselo-soils’ dated to ca 10,95014C BP. A similar trend in increased charcoal indicating increased burning is seen at many sites across North America at this time and it has been suggested by Firestone et al. (2007) that this was caused by an explosion of extra-terrestrial material over northern North America, causing the Younger Dryas climate cooling and Megafaunal extinction. We argue that there is no need to invoke an extraterrestrial cause to explain the charcoal in the fossilized soils. The volume of forest trees that died as a result of the cold Younger Dryas climate would easily have supplied sufficient fuel for intense, large-scale fires and can be used to account for the concentration of charcoal particles. As soils were no longer covered by dense vegetation, much erosion occurred during the Younger Dryas and therefore, at many places, Usselo soils, rich in charcoal, were preserved under aeolian sand dunes.

Historical analysis of landscape change in the eastern boreal mixedwood: A case study in the context of cohort-based management

2013 ◽  
Vol 89 (03) ◽  
pp. 304-314 ◽  
Author(s):  
Charles Latrémouille ◽  
Osvaldo Valeria ◽  
Brian D. Harvey
Keyword(s):  
Spatial Structure ◽  
Historical Analysis ◽  
Shape Index ◽  
Landscape Matrix ◽  
Forest Stands ◽  
Landscape Characteristics ◽  
Natural Fires ◽  
Research And Teaching ◽  
Landscape Characterization ◽  
Stand Attributes

Maintenance of forest spatial structure through forest management is increasingly recognized as an important landscape-level aspect to maintaining biodiversity. In this study, we use forest inventory maps dating from 1965, 1972, 1983, and 1994 to describe the recent historical spatial structure at the Lake Duparquet Research and Teaching Forest (LDRTF) in northwestern Quebec, Canada. Mapped forest stands were classified according to a conceptual cohort model of stand development based on species composition and other stand attributes. Contiguous forest stands of the same cohort class were agglomerated to form relatively uniform patches containing a single cohort class. Landscape spatial structure was defined using four landscape characterization indices: proportion of the landscape, mean patch size, mean distance to nearest neighbour and mean patch shape index. Cohort 1 patches occurred as both small and large units that had complex shapes while Cohort 2 patches occurred as small dispersed units that had simple shapes. Cohort 3 patches dominated the landscape matrix and formed both small and large units that were generally agglomerated in the same vicinity. Our cohort classification of mapped stand polygons was validated by comparing the proportion of land occupied by each cohort in two natural fires (1923 and 1760) that have shaped this area. Theoretical local targets for maintaining cohort structure in the landscape were then formulated based on these historical landscape characteristics.

scholarly journals An ensemble approach to simulate CO<sub>2</sub> emissions from natural fires

2014 ◽  
Vol 11 (1) ◽  
pp. 1443-1478
Author(s):  
A. V. Eliseev ◽  
I. I. Mokhov ◽  
A. V. Chernokulsky
Keyword(s):  
Co2 Emissions ◽  
Global Climate Model ◽  
Burnt Area ◽  
Rcp Scenarios ◽  
Data Set ◽  
Natural Fires ◽  
Ensemble Mean ◽  
Rcp 8.5 ◽  
Fire Characteristics ◽  
The Tropics

Abstract. This paper presents ensemble simulations with the global climate model developed at the A. M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS CM). These simulations were forced by historical reconstruction of external forcings for 850–2005 AD and by the Representative Concentration Pathways (RCP) scenarios till year 2300. Different ensemble members were constructed by varying the governing parameters of the IAP RAS CM module to simulate natural fires. These members are constrained by the GFED–3.1 observational data set and further subjected to Bayesian averaging. This approach allows to select only changes in fire characteristics which are robust within the constrained ensemble. In our simulations, the present-day (1998–2011 AD) global area burnt due to natural fires is (2.1 ± 0.4) × 106 km2 yr−1 (ensemble means and intra-ensemble standard deviations are presented), and the respective CO2 emissions in the atmosphere are (1.4 ± 0.2) PgC yr−1. The latter value is in agreement with the corresponding observational estimates. Regionally, the model underestimates CO2 emissions in the tropics; in the extra-tropics, it underestimates these emissions in north-east Eurasia and overestimates them in Europe. In the 21st century, the ensemble mean global burnt area is increased by 13% (28%, 36%, 51%) under scenario RCP 2.6 (RCP 4.5, RCP 6.0, RCP 8.5). The corresponding global emissions increase is 14% (29%, 37%, 42%). In the 22nd–23rd centuries, under the mitigation scenario RCP 2.6 the ensemble mean global burnt area and respective CO2 emissions slightly decrease, both by 5% relative to their values in year 2100. Under other RCP scenarios, these variables continue to increase. Under scenario RCP 8.5 (RCP 6.0, RCP 4.5) the ensemble mean burnt area in year 2300 is higher by 83% (44%, 15%) than its value in year 2100, and the ensemble mean CO2 emissions are correspondingly higher by 31% (19%, 9%). All changes of natural fire characteristics in the 21st–23rd centuries are associated mostly with the corresponding changes in boreal regions of Eurasia and North America. However, under the RCP 8.5 scenario, increase of the burnt area and CO2 emissions in boreal regions during the 22nd–23rd centuries are accompanied by the respective decreases in the tropics and subtropics.

scholarly journals Contrasting prescription burning and wildfires in California Sierra Nevada national parks and adjacent national forests

2021 ◽  
Vol 30 (4) ◽  
pp. 255
Author(s):  
Jon E. Keeley ◽  
Anne Pfaff ◽  
Anthony C. Caprio
Keyword(s):  
Sierra Nevada ◽  
National Parks ◽  
National Park ◽  
National Forests ◽  
Substantial Impact ◽  
Area Burned ◽  
Natural Fires ◽  
Park Service ◽  
History Of ◽  
Lassen Volcanic National Park

History of prescription burning and wildfires in the three Sierra Nevada National Park Service (NPS) parks and adjacent US Forest Service (USFS) forests is presented. Annual prescription (Rx) burns began in 1968 in Sequoia and Kings Canyon National Parks, followed by Yosemite National Park and Lassen Volcanic National Park. During the last third of the 20th century, USFS national forests adjacent to these parks did limited Rx burns, accounting for very little area burned. However, in 2004, an aggressive annual burn program was initiated in these national forests and in the last decade, area burned by planned prescription burns, relative to area protected, was approximately comparable between these NPS and USFS lands. In 1968, the NPS prescription burning program was unique because it coupled planned Rx burns with managing many lightning-ignited fires for resource benefit. From 1968 to 2017, these natural fires managed for resource benefit averaged the same total area burned as planned Rx burns in the three national parks; thus, they have had a substantial impact on total area burned by prescription. In contrast, on USFS lands, most lightning-ignited fires have been managed for suppression, but increasing attention is being paid to managing wildfires for resource benefit.

scholarly journals GIS Approach to the Solution of the Project for Forecasting the Development of Natural Fires in the Chornobyl Exclusion Zone Based on the Rothermel Model

2020 ◽  
Vol 17 (2) ◽  
pp. 79-94
Author(s):  
Yu. I. Kuzmenko ◽  
◽  
T. D. Lev ◽  
O. G. Tishchenko ◽  
V. N. Piskun ◽  
...  
Keyword(s):  
Exclusion Zone ◽  
Natural Fires

Re-evaluating the origins of late Pleistocene fire areas on Santa Rosa Island, California, USA

2012 ◽  
Vol 78 (2) ◽  
pp. 353-362 ◽  
Author(s):  
Torben C. Rick ◽  
John S. Wah ◽  
Jon M. Erlandson
Keyword(s):  
Late Pleistocene ◽  
Younger Dryas ◽  
Fire Regimes ◽  
Fire Frequency ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sedimentary Deposits ◽  
Natural Fires ◽  
Human Colonization ◽  
Santa Rosa Island

AbstractAt the close of the Pleistocene, fire regimes in North America changed significantly in response to climate change, megafaunal extinctions, anthropogenic burning and possibly, even an extraterrestrial impact. On California's Channel Islands, researchers have long debated the nature of late Pleistocene “fire areas,” discrete red zones in sedimentary deposits, interpreted by some as prehistoric mammoth-roasting pits created by humans. Further research found no evidence that these red zones were cultural in origin, and two hypotheses were advanced to explain their origin: natural fires and groundwater processes. Radiocarbon dating, X-ray diffraction analysis, and identification of charcoal from six red zones on Santa Rosa Island suggest that the studied features date between ~ 27,500 and 11,400 cal yr BP and resulted from burning or heating, not from groundwater processes. Our results show that fire was a component of late Pleistocene Channel Island ecology prior to and after human colonization of the islands, with no clear evidence for increased fire frequency coincident with Paleoindian settlement, extinction of pygmy mammoths, or a proposed Younger Dryas impact event.

scholarly journals Geochemical Evidence for the Control of Fire by Middle Palaeolithic Hominins

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Alex Brittingham ◽  
Michael T. Hren ◽  
Gideon Hartman ◽  
Keith N. Wilkinson ◽  
Carolina Mallol ◽  
...  
Keyword(s):  
Aromatic Hydrocarbons ◽  
Technological Development ◽  
Particulate Emissions ◽  
Middle Palaeolithic ◽  
Natural Fires ◽  
Fire Use ◽  
Multi Stage ◽  
The Social ◽  
Polycyclic Aromatic ◽  
Stage Process

Abstract The use of fire played an important role in the social and technological development of the genus Homo. Most archaeologists agree that this was a multi-stage process, beginning with the exploitation of natural fires and ending with the ability to create fire from scratch. Some have argued that in the Middle Palaeolithic (MP) hominin fire use was limited by the availability of fire in the landscape. Here, we present a record of the abundance of polycyclic aromatic hydrocarbons (PAHs), organic compounds that are produced during the combustion of organic material, from Lusakert Cave, a MP site in Armenia. We find no correlation between the abundance of light PAHs (3–4 rings), which are a major component of wildfire PAH emissions and are shown to disperse widely during fire events, and heavy PAHs (5–6 rings), which are a major component of particulate emissions of burned wood. Instead, we find heavy PAHs correlate with MP artifact density at the site. Given that hPAH abundance correlates with occupation intensity rather than lPAH abundance, we argue that MP hominins were able to control fire and utilize it regardless of the variability of fires in the environment. Together with other studies on MP fire use, these results suggest that the ability of hominins to manipulate fire independent of exploitation of wildfires was spatially variable in the MP and may have developed multiple times in the genus Homo.

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