scholarly journals Wildfire during deposition of the “Illinger Flözzone” (Heusweiler-Formation, “Stephanian B”, Kasimovian–Ghzelian) in the Saar-Nahe Basin (SW-Germany)

2020 ◽  
Author(s):  
Dieter Uhl ◽  
André Jasper
Keyword(s):  
Atmospheric Oxygen ◽  
Anatomical Features ◽  
Seasonally Dry ◽  
Surface Fires ◽  
Dead Trees ◽  
Crown Fires ◽  
Oxygen Conditions ◽  
Wet Tropics

Abstract Wildfires occurred more or less regularly in many Pennsylvanian ecosystems, not only in seasonally dry regions but also in the ever wet tropics. One of the reasons for this was probably the relatively high atmospheric oxygen conditions prevailing during this period. The present study reports evidence for the occurrence of wildfires during deposition of the Upper Pennsylvanian Heusweiler Formation (“Stephanian B”, Kasimovian–Gzhelian) in the intramontane Saar-Nahe (or Saar-Lorraine) Basin in SW-Germany. Based on anatomical features of the charcoal, as well as the co-occurring adpression flora, it seems possible that some of the fires occurred in an ecosystem inhabited by Cordaites. Some of the charcoal fragments exhibit traces of pre-charring decay by fungi, indicating either the consumption of litter by ground or surface fires, or of still standing (partly) dead trees by crown fires.

Structural variability of mature lodgepole pine stands on gently sloping terrain in Taylor Park Basin, Colorado

1994 ◽  
Vol 24 (10) ◽  
pp. 2020-2029 ◽  
Author(s):  
Albert J. Parker ◽  
Kathleen C. Parker
Keyword(s):  
Lodgepole Pine ◽  
Strong Relationship ◽  
Dwarf Mistletoe ◽  
The Past ◽  
Surface Fires ◽  
Dead Trees ◽  
Crown Fires ◽  
Standing Dead ◽  
Standing Dead Trees ◽  
Sloping Terrain

Diameter structures, diameter–age relationships, and spatial pattern of canopy and understory layers in seven stands representative of mature lodgepole pine (Pinusconforta Dougl. ex Loud. ssp. latifolia) forests on gentle (≤5°) slopes in the Taylor Park Basin of Colorado were documented. All stands originated following crown fires 120–140 years ago, during the period of initial Euro-American presence. Two distinct structures were evident among these stands. Four stands had closed canopies (cover >70%), relatively high basal areas and tree densities, low sapling and large seedling densities, numerous standing dead trees, and even-aged diameter distributions. The other three stands had more open canopies (cover <65%), lower basal areas and tree densities, higher densities of saplings and large seedlings, and more even representation across diameter classes. Regeneration tended to occur in small patches in both types of stands. DBH showed a moderate to strong relationship to age in all stands, although suppression of bole-diameter growth was more evident in the closed stands. Structure of the closed stands exemplifies forests that have developed rapidly after canopy fire. Structure of the open stands suggests either low stocking densities following stand-originating crown fires or repetitive surface fires, perhaps reinforced by dwarf mistletoe (Arceuthobiumamericanum Nutt. ex Engelm.) infestation, that have allowed more or less continuous recruitment over the past 120–140 years.

scholarly journals A novel high-content screening approach for the elucidation of C. jejuni biofilm composition and integrity

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Matthew V. X. Whelan ◽  
Jeremy C. Simpson ◽  
Tadhg Ó Cróinín
Keyword(s):  
Atmospheric Oxygen ◽  
Chicken Meat ◽  
Live Cells ◽  
High Throughput Analysis ◽  
Aerobic Conditions ◽  
Poultry Products ◽  
Source Of Infection ◽  
Fluorescent Markers ◽  
Oxygen Conditions ◽  
Bacterial Gastroenteritis

Abstract Background Campylobacter jejuni is the leading cause of bacterial gastroenteritis worldwide and the main source of infection is contaminated chicken meat. Although this important human pathogen is an obligate microaerophile, it must survive atmospheric oxygen conditions to allow transmission from contaminated chicken meat to humans. It is becoming increasingly evident that formation of biofilm plays a key role in the survival of this organism for extended periods on poultry products. We have recently demonstrated a novel inducible model for the study of adherent C. jejuni biofilm formation under aerobic conditions. By taking advantage of supercoiling mediated gene regulation, incubation of C. jejuni with subinhibitory concentrations of the Gyrase B inhibitor novobiocin was shown to promote the consistent formation of metabolically active adherent biofilm. Results In this study, we implement this model in conjunction with the fluorescent markers: TAMRA (live cells) and SytoX (dead cells, eDNA) to develop a novel systematic high-content imaging approach and describe how it can be implemented to gain quantifiable information about the integrity and extracellular polymeric substance (EPS) composition of adherent C. jejuni biofilm in aerobic conditions. We show that this produces a model with a consistent, homogenous biofilm that can be induced and used to screen a range of inhibitors of biofilm adherence and matrix formation. Conclusions This model allows for the first time a high throughput analysis of C. jejuni biofilms which will be invaluable in enabling researchers to develop mechanisms to disrupt these biofilms and reduce the viability of these bacteria under aerobic conditions.

Prescribed fire as a tool to regenerate live and dead serotinous jack pine (Pinus banksiana) stands

2017 ◽  
Vol 26 (6) ◽  
pp. 478 ◽  
Author(s):  
Maria Sharpe ◽  
Hyejin Hwang ◽  
David Schroeder ◽  
Soung Ryoul Ryu ◽  
Victor J. Lieffers
Keyword(s):  
Prescribed Fire ◽  
Natural Regeneration ◽  
Pinus Banksiana ◽  
Mountain Pine Beetle ◽  
Jack Pine ◽  
Crown Fire ◽  
Seedling Regeneration ◽  
Dead Trees ◽  
Crown Fires ◽  
Pine Beetle

This study documents cone opening and natural regeneration of jack pine (Pinus banksiana Lamb.) after burning live and dead stands similar to those killed by the mountain pine beetle (Dendroctonus ponderosae). Trees were killed by girdling in May and were burned in late July, 26 months later. Pairs of live and dead plots were simultaneously burned using three types of fire: surface, intermittent crown and continuous crown fires. Each type of fire was replicated three times; the nine pairs of burns were completed in a 4-day period. After fire, more cones were opened on dead trees than live trees. On dead trees, there was cone opening even when fire charred only the lower part of the bole. Three years after burning, dead stands with continuous crown fires had some of the densest regeneration and the highest rates of stocking. Across all burns in this study, seedling regeneration was best in shallow residual duff and in the more intensely burned plots. Without burning, there was virtually no regeneration 5 years after mortality. The results also show that burning, especially under continuous crown fire, could be used to promote regeneration in dead stands.

scholarly journals Tree community dynamics of a northern Minas Gerais seasonally dry forest

Revista CERES ◽  
2018 ◽  
Vol 65 (3) ◽  
pp. 234-242
Author(s):  
Geovany Heitor Reis ◽  
Rubens Manoel dos Santos ◽  
Diego Gualberto Sales Pereira ◽  
Jean Daniel Morel ◽  
Paola Ferreira Santos
Keyword(s):  
Structural Changes ◽  
Community Dynamics ◽  
Deciduous Forest ◽  
Forest Tree ◽  
Minas Gerais ◽  
Dry Forest ◽  
Seasonally Dry ◽  
Tree Community ◽  
Dead Trees ◽  
New Recruits

ABSTRACT This study aimed to characterize the dynamics, structural changes and floristics of a Northern Minas Gerais Seasonally Deciduous Forest tree community, in a 5 year interval. In 2005, 10 (20 x 20m) plots were allocated. All trees (CBH ≥ 10 cm) were tagged and measured. A second census was carried out in 2010 in order to measure surviving, new recruits and dead trees. In 2005, 46 species were recorded, moving to 45 in 2010. No significant differences were found for Shannon - diversity (H’ = 2.62 nats ind-1 in 2005; H’ = 2.60 nats ind-1 in 2010) and Pielou eveness (J = 0.683 in 2005; J = 0.682 in 2010) in the interval. A total of 57 dead records (rate of 1.64% year-1) were found whereas 18 trees were recruited (rate of 0.53% year-1). Despite the higher mortality as compared to recruitment, the results suggest that the community remained stable in both structural and diversity terms in the interval considered.

scholarly journals Holocene Fire Regime Changes in the Southern Lake Baikal Region Influenced by Climate-Vegetation-Anthropogenic Activity Interactions

Forests ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 978
Author(s):  
Chéïma Barhoumi ◽  
Marianne Vogel ◽  
Lucas Dugerdil ◽  
Hanane Limani ◽  
Sébastien Joannin ◽  
...  
Keyword(s):  
Lake Baikal ◽  
Tree Structure ◽  
Anthropogenic Activity ◽  
Human Populations ◽  
Pinus Sibirica ◽  
Fire Dynamics ◽  
The Holocene ◽  
The Past ◽  
Surface Fires ◽  
Crown Fires

Catastrophic fire years that have taken place during the last decade in Siberia, and more generally within the boreal forest, have been directly linked to global warming and had strong repercussions on boreal ecosystems and human populations. In this context the study of the past dynamics of these fires is essential for understanding their links with climate, vegetation and human activity changes on longer time scales than the last few decades. However, few studies on fire dynamics are available for Siberia, and none have been conducted for the entire Holocene period. This study presents the first fire history reconstruction of this area during the Holocene based on charcoals sequestered in sediments of two lakes located on the southern shore of Lake Baikal, in Siberia. The results show a similar trend in the two lakes, with high frequency and high peak magnitude during the Early Holocene and low magnitudes after 6500 cal. yr BP. This difference is interpreted as crown fires versus surface fires. According to pollen records (Dulikha, Vydrino, Ochkovoe) available near the studied lakes, a vegetation transition occurred at the same time. Picea obovata, which has a tree structure prone to crown fires, was dominant during the Early humid Holocene. After 6500 cal. yr BP, conditions were drier and Pinus sylvestris and Pinus sibirica became the dominant species; their tree structure favors surface fires. In addition to vegetation dynamics, the nearby pollen sequence from Dulikha has been used to provide quantitative estimates of past climate, indicating an Early to Middle Holocene climatic optimum between 8000 and 5000 cal. yr BP and an increase in temperatures at the end of the Holocene. These results have been compared to outputs from regional climate models for the Lake Baikal latitudes. Fire dynamics appear to have been more linked to the vegetation than climatic conditions. Over the past 1500 years, the greater presence of human populations has firstly resulted in an increase in the fire frequency, then in its maintenance and finally in its suppression, which may possibly have been due to very recent fire management, i.e., after ca 500 cal. BP.

A fire history from tree rings in a high-elevation forest of Rocky Mountain National Park

2004 ◽  
Vol 34 (6) ◽  
pp. 1259-1273 ◽  
Author(s):  
Arne Buechling ◽  
William L Baker
Keyword(s):  
20Th Century ◽  
National Park ◽  
Rocky Mountain ◽  
High Elevation ◽  
Rocky Mountain National Park ◽  
Subalpine Forest ◽  
Summer Drought ◽  
High Severity ◽  
Surface Fires ◽  
Crown Fires

Historical fire patterns in a subalpine forest of Rocky Mountain National Park were quantified from an analysis of forest stand ages and fire-scarred trees. A comparatively detailed sample of 3461 tree cores and 212 fire scars was collected from a 9200-ha study area north of Estes Park, Colorado. A total of 41 fire events were identified in the record. Annually precise fire dates, beginning in 1533, include 22 high-severity crown fires, 7 low-severity surface fires, and 8 mixed-severity events with both surface and crown fire components. Fire rotation was estimated for both surface fires (7587 years) and crown fires (346 years). Fire rotation did not appear to vary with fuel characteristics associated with topographical differences in the study area. Fires larger than 300 ha were few, but they determined a large proportion of the area burned since 1700 and were significantly correlated with a reconstructed index of summer drought. Low fire activity in the 20th century was associated with decreased severity and frequency of drought episodes. Long fire rotations preclude definitive conclusions regarding the effects of fire suppression in the 20th century, but relationships between high-severity fires, fuels, and drought suggest that climatic variability remains the primary influence on fire cycles in high-elevation ecosystems of the southern Rocky Mountains.

Predicting Forest Fire Numbers Using Deterministic-Probabilistic Approach

2020 ◽  
pp. 89-100
Author(s):  
Nikolay Viktorovich Baranovskiy
Keyword(s):  
Global Warming ◽  
Forest Fire ◽  
Forest Fires ◽  
Probabilistic Method ◽  
Probabilistic Approach ◽  
Retrospective Data ◽  
Surface Fires ◽  
Crown Fires ◽  
Vegetation Fires ◽  
Forest Fire Danger

The annual task of forecasting forest fire danger is becoming increasingly relevant, especially in the context of global warming. The forecast of surface fires is most important, as more than 80% of all vegetation fires are surface fires. Practically all crown fires develop from surface fires. This chapter discusses the deterministic-probabilistic method for predicting the number of forest fires in a controlled forest area. This methodology is based on the assumption that the number of registered and projected forest fires is related to the probability of their occurrence. The influence of forest fire retrospective data on the predicted number of forest fires for some sites of the Timiryazevskiy forestry of the Tomsk region was studied. This chapter presents the results of a comparative analysis of forecast data and statistics.

4. Containing and suppressing fire

2020 ◽  
pp. 69-100
Author(s):  
Andrew C. Scott
Keyword(s):  
Fire Suppression ◽  
Health Problems ◽  
Fire Prevention ◽  
Low Intensity ◽  
Surface Fires ◽  
Crown Fires ◽  
Urban Fires

‘Containing and suppressing fire’ compares urban and pastoral understandings of fire. Prevention and suppression measures for one country may not be relevant in another, and even in the case of wildfires, one region may contain many different biomes, so formulating fire suppression policies can be complex. Some low-intensity surface fires may help prevent more dangerous crown fires; an urban understanding of all landscape fires as negative is not always helpful. With the increased popularity of living among flammable vegetation, the speed of wildfires can take some people by surprise. In urban fires, smoke has long been recognized as dangerous, but smoke from wildfires and peat burning can also cause health problems.

scholarly journals Diet and Hunting Behavior of the Crane Hawk in Tikal National Park, Guatemala

The Condor ◽  
2001 ◽  
Vol 103 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Jason Sutter ◽  
Walter E. Martínez A. ◽  
Francisco Oliva T ◽  
Nery Oswaldo J ◽  
David F. Whitacre
Keyword(s):  
National Park ◽  
Dietary Overlap ◽  
Forest Types ◽  
Hunting Behavior ◽  
Anatomical Features ◽  
Dead Trees ◽  
Nocturnal Species ◽  
Food Niche ◽  
Prey Items ◽  
Palm Leaf

Abstract We studied the breeding diet and hunting behavior of Crane Hawks (Geranospiza caerulescens) in Tikal National Park, Petén, Guatemala in 1994 and 1995. We observed 227 prey items while conducting observations at six nesting attempts, and during opportunistic sightings in the breeding season. Among 181 identified prey items, rodents comprised 47.5%, lizards 19.9%, frogs 16.0%, bats 6.6%, birds 6.1%, and snakes 2.8%; a juvenile skunk also was represented. Rodents accounted for 77% of estimated biomass, including at least eight species representing terrestrial, cursorial, and arboreal habits. More than half of all prey items weighed <20 g, but 40% weighed >50 g; many were nocturnal species presumably taken from daytime hiding places. We observed hunting attempts in all strata of the forest and in several forest types. Hunting behavior included still-hunting from a perch and probing with head or feet in holes, bromeliads and other epiphytes, palm leaf axils, crotches of branches, behind bark in living and dead trees, and in puddles. Compared to other raptors studied at Tikal, the Crane Hawk had a moderately broad food niche that overlapped most with other raptors deemed dietary generalists. However, the Crane Hawk's unique anatomical features and hunting behavior enabled it to capture diurnally reclusive prey presumably unavailable to many other raptors, thus facilitating relatively low dietary overlap.

scholarly journals Assessment of the Neuroprotective and Stemness Properties of Human Wharton’s Jelly-Derived Mesenchymal Stem Cells under Variable (5% vs. 21%) Aerobic Conditions

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 717
Author(s):  
Ewelina Tomecka ◽  
Wioletta Lech ◽  
Marzena Zychowicz ◽  
Anna Sarnowska ◽  
Magdalena Murzyn ◽  
...  
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Atmospheric Oxygen ◽  
Neuroprotective Effect ◽  
Culture Conditions ◽  
Wharton’S Jelly ◽  
Oxygen Level ◽  
Wharton's Jelly ◽  
Cell Based Therapy ◽  
Oxygen Conditions

To optimise the culture conditions for human Wharton’s jelly-derived mesenchymal stem cells (hWJ-MSCs) intended for clinical use, we investigated ten different properties of these cells cultured under 21% (atmospheric) and 5% (physiological normoxia) oxygen concentrations. The obtained results indicate that 5% O2 has beneficial effects on the proliferation rate, clonogenicity, and slowdown of senescence of hWJ-MSCs; however, the oxygen level did not have an influence on the cell morphology, immunophenotype, or neuroprotective effect of the hWJ-MSCs. Nonetheless, the potential to differentiate into adipocytes, osteocytes, and chondrocytes was comparable under both oxygen conditions. However, spontaneous differentiation of hWJ-MSCs into neuronal lineages was observed and enhanced under atmospheric oxygen conditions. The cells relied more on mitochondrial respiration than glycolysis, regardless of the oxygen conditions. Based on these results, we can conclude that hWJ-MSCs could be effectively cultured and prepared under both oxygen conditions for cell-based therapy. However, the 5% oxygen level seemed to create a more balanced and appropriate environment for hWJ-MSCs.

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