Numerical and Experimental Analysis of Fire Resistance for Steel Structures of Ships and Offshore Platforms

The requirements for the fire resistance of steel structures of oil and gas facilities for transportation and production of hydrocarbons are considered (structures of tankers and offshore platforms). It is found that the requirements for the values of fire resistance of structures under hydrocarbon rather than standard fire conditions are given only for offshore stationary platforms. Experimental studies on the loss of integrity (E) and thermal insulating capacity (I) of steel bulkheads and deck with mineral wool under standard and hydrocarbon fire regimes are presented. Simulation of structure heating was performed, which showed a good correlation with the experimental results (convective heat transfer coefficients for bulkheads of class H: 50 W/m2·K; for bulkheads of class A: 25 W/m2·K). The consumption of mineral slabs and endothermic mat for the H-0 bulkhead is predicted. It is calculated that under a standard fire regime, mineral wool with a density of 80–100 kg/m2 and a thickness of 40 to 85 mm should be used; under a hydrocarbon fire regime, mineral wool with a density above 100 kg/m2 and a thickness of 60–150 mm is required. It is shown that to protect the structures of decks and bulkheads in a hydrocarbon fire regime, it is necessary to use 30–40% more thermal insulation and apply the highest density of fire-retardant material compared to the standard fire regime. Parameters of thermal conductivity and heat capacity of the applied flame retardant in the temperature range from 0 to 1000 °C were clarified.

Amazon fire regimes under climate change scenarios

Fire is one of the most important disturbances of the earth-system, shaping the biodiversity of ecosystems and particularly forests. Anthropogenic drivers such as climatic change and other human activities could produce potentially abrupt changes in fire regimes, triggering more profound transformations like the transition from forests to savannah or grasslands ecosystems. Large biodiversity loss could be produced if these transitions occur. Climatic change could cause conditions that enhance fire ignition and spread, which may potentially produce more extensive, intense, and frequent fires. In this work, by considering climate projections for the 21st century, we evaluate the possible changes in the Amazon region's fire regime. We parametrize a fire model using remote sensing data on fire extension and temperature. In the context of our model, there are two possible regime changes: the critical regime that implies high variability in fire extension and mega-fires, and an absorbing phase transition which would produce the extinction of the forest and transition to a different vegetation state. The fitted model and the projections suggest that the Amazon region is not close to any of these regime changes, but other factors not included in the model could result crucial in determining such critical transitions.

Climate change, fire return intervals and the growing risk of permanent forest loss in boreal Eurasia

Climate change has driven an increase in the frequency and severity of fires in Eurasian boreal forests. A growing number of field studies have linked the change in fire regime to post-fire recruitment failure and permanent forest loss. In this study we used four burnt area and two forest loss datasets to calculate the landscape-scale fire return interval (FRI) and associated risk of permanent forest loss. We then used machine learning to predict how the FRI will change under a high emissions scenario (SSP3-7.0) by the end of the century. We found that there is currently 133 000 km2 at high, or extreme, risk of fire-induced forest loss, with a further 3 M km2 at risk by the end of the century. This has the potential to degrade or destroy some of the largest remaining intact forests in the world, negatively impact the health and economic wellbeing of people living in the region, as well as accelerate global climate change.

Northern spotted owl nesting forests as fire refugia: a 30-year synthesis of large wildfires

Background The northern spotted owl (Strix occidentalis caurina) is an Endangered Species Act-listed subspecies that requires coniferous forests with structurally complex and closed-canopy old-growth characteristics for nesting. With climate change, large wildfires are expected to become more common within the subspecies’ range and an increasing threat to these types of forests. Understanding fire severity patterns related to suitable nesting forest will be important to inform forest management that affects conservation and recovery. We examined the relationship between fire severity and suitable nesting forest in 472 large wildfires (> 200 ha) that occurred in the northern spotted owl range during 1987–2017. We mapped fire severities (unburned-low, moderate, high) within each fire using relative differenced normalized burn ratios and quantified differences in severity between pre-fire suitable nesting forest (edge and interior) and non-nesting forest. We also quantified these relationships within areas of three fire regimes (low severity, very frequent; mixed severity, frequent; high severity, infrequent). Results Averaged over all fires, the interior nesting forest burned at lower severity than edge or non-nesting forest. These relationships were consistent within the low severity, very frequent, and mixed severity, frequent fire regime areas. All forest types burned at similar severity within the high severity, infrequent fire regime. During two of the most active wildfire years that also had the largest wildfires occurring in rare and extreme weather conditions, we found a bimodal distribution of fire severity in all forest types. In those years, a higher amount—and proportion—of all forest types burned at high severity. Over the 30-year study, we found a strong positive trend in the proportion of wildfires that burned at high severity in the non-nesting forests, but not in the suitable nesting forest types. Conclusions Under most wildfire conditions, the microclimate of interior patches of suitable nesting forests likely mitigated fire severity and thus functioned as fire refugia (i.e., burning at lower severity than the surrounding landscape). With changing climate, the future of interior forest as fire refugia is unknown, but trends suggest older forests can dampen the effect of increased wildfire activity and be an important component of landscapes with fire resiliency.

Effects of Forest Fire on the Regeneration Potentials of Tree Species in Olokemeji Forest Reserve, Ogun State, Nigeria

Effects of forest fire on the regeneration potential of trees at Olokemeji Forest Reserve was established in this study. The Olokemeji fire experimental plot was selected at the reserve. The site was divided into three plots; late fire treatment was applied to Plot A, Early fire treatment was also applied to Plot B and no fire treatment at plot C (Control plot). The diameter at breast height (dbh) and tree height (m) of the tree species in the plots were assessed prior and post fire treatment. The regeneration potential of the selected plots after burning were assessed through the occurrence of saplings and seedlings obtained. The highest basal area (m2) were found in plot C followed by plot B and Plot C with mean value of 0.64, 0.55 and 0.30 m2 respectively. The number of stems per plot ranged from 25 to 67. The regeneration potentials of the three plots were found to be noteworthy. Early and late year fire regime adopted had both positive and negative effect on the regeneration potentials of tree species. This study has established the effect and relevance of fire on forest and wildlife management. It’s therefore recommended in this study that Prescribed or controlled burning should be encouraged as appropriate sivilcultural management tool for stimulating basal area growth, natural regeneration, production of tree species seedlings and saplings.