scholarly journals Are Wildland Fires Increasing Large Patches of Complex Early Seral Forest Habitat?

Diversity ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 157 ◽  
Author(s):  
Dominick A. DellaSala ◽  
Chad T. Hanson
Keyword(s):  
Fire Severity ◽  
Western Usa ◽  
High Severity ◽  
Open Forest ◽  
Time Period ◽  
Minor Portion ◽  
A Minor ◽  
First Time ◽  
A Current ◽  
Current Risk

High-severity fire creates patches of complex early seral forest (CESF) in mixed-severity fire complexes of the western USA. Some managers and researchers have expressed concerns that large high-severity patches are increasing and could adversely impact old forest extent or lead to type conversions. We used GIS databases for vegetation and fire severity to investigate trends in large (>400 ha) CESF patches in frequent-fire forests of the western USA, analyzing four equal time periods from 1984 to 2015. We detected a significant increase in the total area of large patches relative to the first time period only (1984–1991), but no significant upward trend since the early 1990s. There was no significant trend in the size of large CESF patches between 1984 and 2015. Fire rotation intervals for large CESF patches ranged from ~12 centuries to over 4000 years, depending on the region. Large CESF patches were highly heterogeneous, internally creating ample opportunities for fire-mediated biodiversity. Interior patch areas far removed from the nearest low/moderate-severity edges comprised a minor portion of high-severity patches but may be ecologically important in creating pockets of open forest. There was ample historical evidence of large CESF patches but no evidence of increases that might indicate a current risk of ecosystem-type shifts.

Post-fire response variability in Mediterranean Basin tree species in Portugal

2013 ◽  
Vol 22 (7) ◽  
pp. 919 ◽  
Author(s):  
Filipe X. Catry ◽  
Juli G. Pausas ◽  
Francisco Moreira ◽  
Paulo M. Fernandes ◽  
Francisco Rego
Keyword(s):  
Mediterranean Basin ◽  
Plant Traits ◽  
Fire Severity ◽  
Natural Disturbance ◽  
Minor Role ◽  
Mediterranean Species ◽  
High Severity ◽  
A Minor ◽  
Stem Mortality ◽  
Tree Characteristics

Fire is the most important natural disturbance driving vegetation dynamics in the Mediterranean Basin. However, studies relating fire-induced tree responses to both fire severity and plant traits are still scarce in this region. We aimed to investigate such relationships further and to develop simple models that could help improve forest management in these fire-prone ecosystems. We compiled data from 16 fire sites in different regions and used models to relate post-fire responses of 4155 trees from 14 species with fire severity indicators and tree characteristics. The influence of several spatiotemporal factors at the site level was also considered. Results showed that pine mortality was usually high and mainly determined by fire severity, whereas plant traits played a minor role. In contrast, mortality of broadleaved trees was usually low, even for high-severity fire, but most trees were top-killed. Stem mortality increased with fire severity and decreased with bark thickness and tree size. The models for predicting individual mortality of pines and stem mortality of broadleaves showed very good performance, including when validated against independent datasets. Our results suggest that it is possible to accurately predict the most common post-fire responses of Mediterranean species based on simple fire and tree characteristics.

PERSPECTIVE DEVELOPMENT OF WORLD PRODUCTION OF FEEDS FOR AQUACULTURE: ALTERNATIVE SOURCES OF RAW MATERIALS

2017 ◽  
pp. 67-78
Author(s):  
Lina Yurievna Lagutkina
Keyword(s):  
Raw Materials ◽  
Limiting Factors ◽  
Current Status ◽  
Feed Production ◽  
The World ◽  
Market Trends ◽  
Alternative Sources ◽  
World Industry ◽  
First Time ◽  
A Current

The author of the article discloses the prospects of development of the world feed production for aquaculture based on the analysis of key innovative technological and market trends. The author specifies that shortage, high cost, low ecological compatibility of traditional raw materials - fish flour - are among major limiting factors in the development of production of feeds for aquaculture. This fact, in turn, limits sustainable development of aquaculture both in Russia, and in the world in general. The article presents the overview of a current status of the world industry of feed production in aquaculture, where the regional situation is studied, as well. For the first time, there is given the outlook of innovative technologies in feed production based on the alternative sources of protein (on the example of projects of leading aquabiotechnological companies) which will determine industry’s objectives for the mid-term perspective.

scholarly journals Fire and Mechanical Forest Management Treatments Support Different Portions of the Bird Community in Fire-Suppressed Forests

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 150
Author(s):  
Lance Jay Roberts ◽  
Ryan Burnett ◽  
Alissa Fogg
Keyword(s):  
Sierra Nevada ◽  
Fire Severity ◽  
Bird Species ◽  
Bird Community ◽  
Fire Disturbance ◽  
Long Term Effects ◽  
High Severity ◽  
Commercial Thinning ◽  
Silvicultural Management ◽  
Total Community

Silvicultural treatments, fire, and insect outbreaks are the primary disturbance events currently affecting forests in the Sierra Nevada Mountains of California, a region where plants and wildlife are highly adapted to a frequent-fire disturbance regime that has been suppressed for decades. Although the effects of both fire and silviculture on wildlife have been studied by many, there are few studies that directly compare their long-term effects on wildlife communities. We conducted avian point counts from 2010 to 2019 at 1987 in situ field survey locations across eight national forests and collected fire and silvicultural treatment data from 1987 to 2016, resulting in a 20-year post-disturbance chronosequence. We evaluated two categories of fire severity in comparison to silvicultural management (largely pre-commercial and commercial thinning treatments) as well as undisturbed locations to model their influences on abundances of 71 breeding bird species. More species (48% of the community) reached peak abundance at moderate-high-severity-fire locations than at low-severity fire (8%), silvicultural management (16%), or undisturbed (13%) locations. Total community abundance was highest in undisturbed dense forests as well as in the first few years after silvicultural management and lowest in the first few years after moderate-high-severity fire, then abundance in all types of disturbed habitats was similar by 10 years after disturbance. Even though the total community abundance was relatively low in moderate-high-severity-fire habitats, species diversity was the highest. Moderate-high-severity fire supported a unique portion of the avian community, while low-severity fire and silvicultural management were relatively similar. We conclude that a significant portion of the bird community in the Sierra Nevada region is dependent on moderate-high-severity fire and thus recommend that a prescribed and managed wildfire program that incorporates a variety of fire effects will best maintain biodiversity in this region.

scholarly journals Nanocrystalline TiO2Electrodes Exhibiting High Storage Capacity and Stability in Rechargeable Lithium Batteries

1995 ◽  
Vol 18 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Sui-Yang Huang ◽  
Ladislav Kavan ◽  
Andreas Kay ◽  
Michael Grätzel ◽  
Ivan Exnar
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Discharge Voltage ◽  
Unit Weight ◽  
Nanocrystalline Films ◽  
Rechargeable Lithium Batteries ◽  
Capacity Loss ◽  
High Storage Capacity ◽  
First Time ◽  
A Current

Nanocrystalline TiO2films were explored for the first time as electrode material for a rechargeable lithium intercalation cell, i.e., Li/LiCF3SO3+ PC/TiO2. Two kinds of nanocrystalline films, TiO2F387 (Degussa) and TiO2colloid-240, were investigated. These films exhibited excellent performance renderings them a promising choice for secondary battery applications. At a current density of 0.01 mA/cm2, two voltage plateaus at 1.78 and 1.89 V were observed for TiO2F387 films during charge and discharge, respectively. The TiO2electrode charge capacity per unit weight rose with decreasing current density. The highest capacity, obtained at a current density of 0.005 mA/cm2and a final discharge voltage of 1.4 V, was 265 mAh/g corresponding to a lithium insertion ratio ofx= 0.8. Nanocrystalline TiO2colloid-240 films showed a similar performance. The cycle life of a TiO2colloid-240 cell at a high current density was found to be excellent; a capacity loss lower than 14% has been observed over 100 charge/discharge cycles.

The Relationship Between City “Greenness” and Homicide in the US: Evidence Over a 30-Year Period

2021 ◽  
pp. 001391652110450
Author(s):  
Jonnell C. Sanciangco ◽  
Gregory D. Breetzke ◽  
Zihan Lin ◽  
Yuhao Wang ◽  
Kimberly A. Clevenger ◽  
...  
Keyword(s):  
Violent Crime ◽  
P Value ◽  
Homicide Rates ◽  
Violence Reduction ◽  
Time Period ◽  
The Us ◽  
Longitudinal Effects ◽  
Curve Modeling ◽  
First Time ◽  
Us Cities

Residents in US cities are exposed to high levels of stress and violent crime. At the same time, a number of cities have put forward “greening” efforts which may promote nature’s calming effects and reduce stressful stimuli. Previous research has shown that greening may lower aggressive behaviors and violent crime. In this study we examined, for the first time, the longitudinal effects over a 30-year period of average city greenness on homicide rates across 290 major cities in the US, using multilevel linear growth curve modeling. Overall, homicide rates in US cities decreased over this time-period (52.1–33.5 per 100,000 population) while the average greenness increased slightly (0.41–0.43 NDVI). Change in average city greenness was negatively associated with homicide, controlling for a range of variables (β = −.30, p-value = .02). The results of this study suggest that efforts to increase urban greenness may have small but significant violence-reduction benefits.

Influence of wildfire severity on geomorphic features and riparian vegetation of forested streams of the Sierra Nevada, California, USA

2020 ◽  
Vol 29 (7) ◽  
pp. 611
Author(s):  
Breeanne K. Jackson ◽  
S. Mažeika P. Sullivan
Keyword(s):  
Sierra Nevada ◽  
Riparian Vegetation ◽  
Fire Severity ◽  
Riparian Ecosystems ◽  
High Severity ◽  
Sediment Size ◽  
Rim Fire ◽  
Geomorphic Features ◽  
Biodiversity And Ecosystem Function ◽  
Riparian Plant

Fires are a common feature of many landscapes, with numerous and complex ecological consequences. In stream ecosystems, fire can strongly influence fluvial geomorphic characteristics and riparian vegetation, which are structural components of stream–riparian ecosystems that contribute to biodiversity and ecosystem function. However, the effects of fire severity on stream–riparian ecosystems in California’s Sierra Nevada region (USA) are not well described, yet critical for effectively informing fire management and policy. At 12 stream reaches paired by fire severity (one high-severity burned, one low-severity burned), no significant differences were found in riparian plant community cover and composition or stream geomorphic characteristics 2–15 years following wildfire. In addition, minimal changes in riparian vegetation and stream geomorphic properties were observed in the first summer following the extensive and severe Rim Fire. However, an upstream-to-downstream influence of multiple fire occurrences was observed over the previous 81 years within each catchment on stream geomorphic metrics, including sediment size, embeddedness and channel geometry, at our study reaches. The inconsistent effects of wildfire on stream–riparian vegetation and geomorphic characteristics over space and time may be related to time since fire and precipitation.

scholarly journals Impact of VOCs on the formation of ozone in a central China city during severe pollution periods

2018 ◽  
Author(s):  
Bowei Li ◽  
Steven Sai Hang Ho ◽  
Sunling Gong ◽  
Jingwei Ni ◽  
Huairui Li ◽  
...  
Keyword(s):  
Temporal Variations ◽  
Central China ◽  
Compressed Natural Gas ◽  
Pmf Model ◽  
Sampling Campaign ◽  
Time Period ◽  
Ozone Formation Potential ◽  
Range Transport ◽  
Volatile Organic ◽  
First Time

Abstract. In this work, a five-month sampling campaign was conducted for volatile organic compounds (VOCs) for the first time in Zhengzhou City, Henan province, China, where ozone (O3) pollution has shown an increasing trend in recent years. Fifty-seven VOCs defined by the Photochemical Assessment Monitoring Stations (PAMS) were sampled using canister method. Meanwhile, other O3 precursor gases were monitored online at four different sites between the time period of May–September, 2017. The results indicated that the average mixing ratio of ΣPAMS (31.57 ± 23.35 ppbv) in Zhengzhou was lower than the other megacities in China, while alkyne was in a significantly higher proportion. The abundances, compositions and ratios of PAMS showed strong spatial and temporal variations. Alkenes were the largest contributors to the ozone formation potential (OFP). On clear days, higher O3 levels were often accompanied with high ΣPAMS/NOx ratio at each site, demonstrating that the VOCs were more sensitive during the O3 formation period in Zhengzhou. Furthermore, source apportionmemt was conducted with Positive Matrix Factorization (PMF) model, and it was found that the use of compressed natural gas (CNG), the evaporation of gasoline and the exhaust from vehicles were the important sources for ambient VOCs at all four sites. Besides, the meterological conditions and long-range transport from other surrounding provinces also had an impact on the air quality determined using the cluster analysis. It is worth mentioning that the reduction in VOCs' emissions is necessary to suppress the O3 pollution.

Do we need medical leadership or medical engagement?

2015 ◽  
Vol 28 (3) ◽  
pp. 173-184 ◽  
Author(s):  
Peter Spurgeon ◽  
Paul Long ◽  
John Clark ◽  
Frank Daly
Keyword(s):  
Care Quality ◽  
Current Evidence ◽  
Organisational Performance ◽  
Content Type ◽  
Care Quality Commission ◽  
The Uk ◽  
Medical Leadership ◽  
First Time ◽  
Practical Implications ◽  
A Current

Purpose – The purpose of this paper is to address issues of medical leadership within health systems and to clarify the associated conceptual issues, for example, leadership versus management and medical versus clinical leadership. However, its principle contribution is to raise the issue of the purpose or outcome of medical leadership, and, in this respect, it argues that it is to promote medical engagement. Design/methodology/approach – The approach is to provide evidence, both from the literature and empirically, to suggest that enhanced medical engagement leads to improved organisational performance and, in doing so, to review the associated concepts. Findings – Building on current evidence from the UK and Australia, the authors strengthen previous findings that effective medical leadership underpins the effective organisational performance. Research limitations/implications – There is a current imbalance between the size of the databases on medical engagement between the UK (very large) and Australia (small but developing). Practical implications – The authors aim to equip medical leaders with the appropriate skill set to promote and enhance greater medical engagement. The focus of leaders in organisations should be in creating a culture that fosters and supports medical engagement. Social implications – This paper provides empowerment of medical professionals to have greater influence in the running of the organisation in which they deliver care. Originality/value – The paper contains, for the first time, linked performance data from the Care Quality Commission in the UK and from Australia with the new set of medical engagement findings.

scholarly journals Finding of Agr Phase Variants in Staphylococcus aureus

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Vishal Gor ◽  
Aya J. Takemura ◽  
Masami Nishitani ◽  
Masato Higashide ◽  
Veronica Medrano Romero ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Virulence Factors ◽  
Phase Variation ◽  
Accessory Gene ◽  
Content Type ◽  
Accessory Gene Regulator ◽  
Immune Mediated ◽  
A Minor ◽  
First Time ◽  
Phase Variants

ABSTRACT Staphylococcus aureus is an important human pathogen whose success is largely attributed to its vast arsenal of virulence factors that facilitate its invasion into, and survival within, the human host. The expression of these virulence factors is controlled by the quorum sensing accessory gene regulator (Agr) system. However, a large proportion of clinical S. aureus isolates are consistently found to have a mutationally inactivated Agr system. These mutants have a survival advantage in the host but are considered irreversible mutants. Here we show, for the first time, that a fraction of Agr-negative mutants can revert their Agr activity. By serially passaging Agr-negative strains and screening for phenotypic reversion of hemolysis and subsequent sequencing, we identified two mutational events responsible for reversion: a genetic duplication plus inversion event and a poly(A) tract alteration. Additionally, we demonstrate that one clinical Agr-negative methicillin-resistant S. aureus (MRSA) isolate could reproducibly generate Agr-revertant colonies with a poly(A) tract genetic mechanism. We also show that these revertants activate their Agr system upon phagocytosis. We propose a model in which a minor fraction of Agr-negative S. aureus strains are phase variants that can revert their Agr activity and may act as a cryptic insurance strategy against host-mediated stress. IMPORTANCE Staphylococcus aureus is responsible for a broad range of infections. This pathogen has a vast arsenal of virulence factors at its disposal, but avirulent strains are frequently isolated as the cause of clinical infections. These isolates have a mutated agr locus and have been believed to have no evolutionary future. Here we show that a fraction of Agr-negative strains can repair their mutated agr locus with mechanisms resembling phase variation. The agr revertants sustain an Agr OFF state as long as they exist as a minority but can activate their Agr system upon phagocytosis. These revertant cells might function as a cryptic insurance strategy to survive immune-mediated host stress that arises during infection.

scholarly journals Occurrence of L1014F and L1014S mutations in insecticide resistant Culex quinquefasciatus from filariasis endemic districts of West Bengal, India

2022 ◽  
Vol 16 (1) ◽  
pp. e0010000
Author(s):  
Priyanka Rai ◽  
Dhiraj Saha
Keyword(s):  
Culex Quinquefasciatus ◽  
West Bengal ◽  
Economic Status ◽  
Minor Role ◽  
Resistance Development ◽  
Vector Population ◽  
A Minor ◽  
First Time

Introduction Lymphatic filariasis causes long term morbidity and hampers the socio-economic status. Apart from the available treatments and medication, control of vector population Culex quinquefasciatus Say through the use of chemical insecticides is a widely applied strategy. However, the unrestrained application of these insecticides over many decades has led to resistance development in the vectors. Methods In order to determine the insecticide susceptibility/resistance status of Cx. quinquefasciatus from two filariasis endemic districts of West Bengal, India, wild mosquito populations were collected and assayed against six different insecticides and presence of L1014F; L1014S kdr mutations in the voltage-gated sodium channel gene was also screened along with the use of synergists to evaluate the role of major detoxifying enzymes in resistance development. Results The collected mosquito populations showed severe resistance to insecticides and the two synergists used–PBO (piperonyl butoxide) and TPP (triphenyl phosphate), were unable to restore the susceptibility status of the vector thereupon pointing towards a minor role of metabolic enzymes. kdr mutations were present in the studied populations in varying percent with higher L1014F frequency indicating its association with the observed resistance to pyrethroids and DDT. This study reports L1014S mutation in Cx. quinquefasciatus for the first time.

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