Low Fire Research Articles

Phosphorylated Metal-Organic Framework for Reducing Fire Hazards of Poly(Methyl Methacrylate).

The low fire safety performance (flame retardant and antistatic properties) of poly(methyl methacrylate) (PMMA) has severely limited practical applications. Here, a phosphorylated Zn-based metal-organic framework (ZIF-8-P) is employed as an effective flame retardant and antistatic agent to reduce the fire risk of PMMA. Encouragingly, the as-prepared PMMA/ZIF-8-P composite demonstrated not merely better mechanical properties (e.g., a rise of ca. 136.9% and 175.0% in the reduced modulus and hardness; a higher storage modulus), but also efficient fire safety properties (e.g., lower surface resistance; a decrease of ca. 73.1% in the peak heat release rate; a lower amount of total pyrolysis products), surpassing those of pure PMMA and a PMMA/ZIF-8 composite without phytic acid modification. Mechanism analysis is conducted to reveal the critical role of catalytic charring, char reinforcing, and the dilution of nonflammable gases from ZIF-8 additives during the combustion and pyrolysis process. Our study paves a promising way to achieve high performance PMMA composites.

Fire severity and pre-fire forest composition affect Northern Hawk Owl presence in burned forests in western North America

Wildfire is an important natural disturbance shaping the boreal forests of North America. Not surprisingly, many species have adapted to benefit from the structural or functional changes in response to fire. Of these post-fire species, the Northern Hawk Owl (Surnia ulula caparoch) is one of the least studied species on the continent. We surveyed 18 recent fires in the boreal forest region of Alberta, Canada, ranging in age from 1 to 14 years post-fire, to improve our understanding of post-fire habitat relationships for this species. Hawk owls were present in fires ranging from 2 to 11 years post-fire, and occupied burns ranging in size from 1,000–272,000 ha. Hawk owls were strongly associated with areas of older deciduous-dominated forest, based on pre-fire forest inventory. Hawk owl responses to pre-fire forest age structure and composition were consistently stronger at the 1000 m radius (home range) extent than the 400 m (nest site) extent. We also found hawk owls responded differently to time since fire, with an immediate (e.g. 2–6 yr) response to low severity fire and a delayed (10–11 yr) response to high severity fire. We recommend future surveys for this species be conducted earlier in the day, ideally within a few hours of sunrise, based on the timing of detection in this study. Finally, the retention of large patches (e.g. > 300 ha) of older, deciduous-dominated habitat within post-fire forests may be an important management consideration for the conservation of hawk owls and other post-fire species.

Canopy plant composition and structure of Cape subtropical dune thicket are predicted by the levels of fire exposure.

The subtropical dune thicket (hereafter "dune thicket") of the Cape Floristic Region experiences a wide range of fire exposure throughout the landscape, unlike other dry rainforest formations that rarely experience fire. We sought to determine how fire exposure influences species composition and the architectural composition of dune thicket. We used multivariate analysis and diversity indices based on cover abundance of species to describe the species composition, architectural guild composition and structure of dune thicket sites subject to different levels of fire exposure, namely low (fire return interval of >100 years), moderate (fire return interval of 50-100 years), and high (fire return interval of 10-50 years). The diversity, cover abundance and architectural guild cover abundance of dune thicket canopy species were strongly influenced by the level of fire exposure such that each level was associated with a well-circumscribed vegetation unit. Dune thickets subject to low fire exposure comprises a floristically distinct, low forest characterized by shrubs with one-to-few upright stems (ca. 4-8 m tall) and a relatively small canopy spread (vertical growers). Of the 25 species in this unit, 40% were restricted to it. Dune thickets subject to moderate fire exposure had the highest abundance of lateral spreaders, which are multi-stemmed (ca. 3-6 m tall) species with a large canopy spread and lower stature than vertical growers. None of the 17 species found in this unit was restricted to it. Dune thickets subject to high fire exposure had the highest abundance of hedge-forming shrubs, these being low shrubs (ca. 0.6-1.4 m tall), with numerous shoots arising from an extensive system of below-ground stems. Of the 20 species in this unit, 40% were restricted to it. Multivariate analysis identified three floristic units corresponding to the three fire exposure regimes. Compositional structure, in terms of species and architectural guilds, was most distinctive for dune thickets subject to high and low fire exposure, while the dune thicket subject to moderate fire exposure showed greatest compositional overlap with the other units. Fire exposure profoundly influenced the composition and structure of dune thicket canopy species in the Cape Floristic Region. In the prolonged absence of fire, the thicket is invaded by vertical-growing species that overtop and outcompete the multi-stemmed, laterally-spreading shrubs that dominate this community. Regular exposure to fire selects for traits that enable thicket species to rapidly compete for canopy cover post-fire via the prolific production of resprouts from basal buds below- and above-ground. The trade-off is that plant height is constrained, as proportionately more resources are allocated to below-ground biomass.

Marked rebound of agricultural fire emissions in Asia after the outbreak of COVID-19

East and South Asia are major hotspots of crop straw burning worldwide, with profound impacts on air quality and climate change. The Northeast China Plain (NECP) and Punjab, India, are two of the most fertile areas for crop production, which have large-scale agricultural fires during post-harvest seasons. Leveraging established fire-emission databases and satellite-retrieved agricultural fire spots, we show that, while the years 2018 and 2019 recorded low agricultural fire emissions in both the NECP and Punjab, probably due to the implementation of crop straw sustainable management, fire emissions markedly rebounded in 2020, reaching about 190% and 150% of 2019 levels, respectively. The COVID-19 lockdown measures somewhat disrupted eco-friendly crop straw management through restrictions on labor and transportation availability, such that farmers may have had to burn off crop wastes to clear up the land. We further demonstrate that the increased fire emissions in the NECP resulted in serious particulate matter pollution during the fire season in spring 2020, as opposed to considerable decreases in particles from fossil fuel emissions caused by the COVID-19 lockdown. This study suggests the unintended impacts of the COVID-19 pandemic on the agricultural sector and human health.

Increasing prevalence of severe fires change the structure of arthropod communities: Evidence from a meta‐analysis

Abstract Animal ecology and evolution are shaped by environmental perturbations, which are undergoing unprecedented alterations due to climate change. Fire is one such perturbation that causes significant disruption by causing mortality and altering habitats and resources for animals. Fire regimes are changing on a global scale, but the effects of these changes on animal communities are poorly understood. Arthropods are one of the most ubiquitous and diverse animal taxa on the planet and their populations are sensitive to environmental change. Given their wide‐ranging impacts on ecosystem functioning, a better understanding of arthropod responses to changing fire regimes is critical and may also provide more general insights into how other groups might respond to fire. Here, we provide a comprehensive meta‐analytical assessment of how fire influences the arthropod community across habitats and functional groups. Using data from 130 peer‐reviewed papers across the globe, we tested how a variety of fire characteristics, including management regime, severity and time‐since‐fire affect arthropod populations and communities across habitats. Our results show that arthropod communities display substantial variation in response to fire and that community‐level responses are most likely to be detected within the first year. Responses also vary depending on fire characteristics and habitat. Specifically, while community metrics such as diversity were increased by low severity fires, they were reduced by high severity fires. Likewise, evenness increased after prescribed burns but was reduced after wildfire. Measures of arthropod community structure decreased following fires in deserts and forests. Across the entire arthropod community, fire also had variable effects on community diversity. Fire tended to have a negative effect size on arthropods across life stages, but responses did vary among groups. Nearly all functional groups exhibited a negative response to fire with the exception of herbivores, for which abundance, diversity and richness increased after fire. Our results suggest that the increasing prevalence of high‐severity wildfires are changing the structure of arthropod communities. Given their ubiquitous presence and diverse roles in terrestrial ecosystems, these community changes are likely to affect ecosystem functioning in various ways, including through increased herbivory. Read the free Plain Language Summary for this article on the Journal blog.

Burning the seed bank: Seed response of eight species to different fire intensities in Patagonian steppe

AbstractQuestionsFire intensity influences the soil seed bank in fire‐prone environments. The aim of this investigation was to study the effects of fire intensity on seed germination and seedling growth of native species which belong to three functional groups (grasses, shrubs, and fire ephemerals). We addressed the following questions: (1) How does fire intensity affect the seed germination and seedling growth of the functional groups? Are there differences among species within each functional group? (2) How do seed traits (shape, size, protection structures of seeds, and embryo position) influence the resistance to high temperatures? (3) What conclusions at the community level can we infer from our results?LocationNorthwestern Patagonian grasslands, Argentina.MethodsWe performed two experimental burns using different amounts of grassland biomass to simulate low and high fire intensities on sowed seeds of eight native species (four grasses, two shrubs, and two fire ephemerals). We calculated the frequency of seed germination, mean germination time, and estimated seedling growth by weighing the dry biomass (roots and leaves). We examined the relationship of seed mass, length, and shape to the percentage of seed germination in low‐ and high‐temperature treatments.ResultsBoth temperature treatments negatively affected the seed germination of all functional groups and species, except for the fire ephemeral Boopis gracilis with protected linear embryos. Among grasses, the presence of protective structures in Pappostipa speciosa seeds and of hairs in Poa lanuginosa seeds probably provides resistance to high temperatures. Root growth of seedlings of the grasses Pappostipa speciosa and Festuca pallescens was stimulated by high‐temperature treatment ensuring post‐fire establishment.ConclusionsOur results suggest that fire intensity influences the post‐fire seed germination and seedling growth of the three dominant functional groups of northwestern Patagonian grasslands. In addition, we can affirm that the species of these functional groups have adaptations to resist wildfires and are capable of exploiting post‐fire resources.

Scorched earth tactics of the “Islamic State” after its loss of territory: intentional burning of farmland in Iraq and Syria

Recent literature shows increasing interest in analyzing causes of what was referred to as “unusual” fires in Iraq and Syria in 2019. Here, we examine the causes of uncontrolled and irregular fires within farmlands in parts of the two countries in 2019–2020 and quantify their extent spatiotemporally using a combination of medium and coarse-resolution satellite imagery, land cover, precipitation, temperature data, and multiple sources of armed violence data. Our analysis reveals the extent of the deliberate arson of farmland in Iraq and Northeast Syria in 2019–2020. In comparison, only a few fires of farmland were observed in 2007–2013 in Iraq, and Al-Hassakeh, Syria, that became a stronghold of the Islamic State (IS) in 2013. In 2014–2017, we find evidence for increased farmland fires in various locations that closely tracked the military withdrawal of IS between 2015/2016 and 2017 when it lost most of its territory. We find that although the burned area in wheat-producing regions of Iraq (Ninewa and Kirkuk) and Syria have recently increased, the increase in the percentage burned area of agricultural lands in Iraq’s Ninewa and Kirkuk was not unprecedented. MODIS overestimates burned areas when in low fire activity while it underestimates it when fire activity is high, compared to a Landsat–Sentinel-2 combination. A significant positive relationship (r = 0.83) exists between the number of IS-related incidents and the percent burned agricultural area during 2019, which raises questions about the future strategy of the IS terror group and its use and targeting of the water-food complex.

Diffusion of indigenous fire management and carbon-credit programs: Opportunities and challenges for “scaling-up” to temperate ecosystems

Savanna burning programs across northern Australia generate millions of dollars per year for Indigenous communities through carbon and other greenhouse gas (GHG) markets. In catalyzing Indigenous knowledge and workforce to mitigate destructive wildfires, these programs are considered a success story on a range of social, ecological and economic measures. Scaling-up to temperate ecosystems requires a focus on applying the architecture and governance of these programs, and accounting for fundamental differences in context. We examine the opportunities and challenges in applying the architecture of savanna burning to an Indigenous Fire Management (IFM) program in central British Columbia, Canada (the Chilcotin). The Chilcotin project involves Yunesit’in and Xeni Gwet’in First Nations, and we draw from eight key elements of the Australian savanna burning model to identify a project area that includes Aboriginal title and reserve lands. The area encompasses Interior Douglas Fir (IDF) and Sub-Boreal Pine—Spruce (SBPS) biogeoclimatic zones, or dry forest and grassland ecosystems where low intensity fires are applied by community members to remove forest fuels, with the goal of mitigating wildfires and associated GHG emissions. The multi-decadal intervals between contemporary fires in the Chilcotin region make it challenging to accurately document historical fire location, scale and intensity, and thus to establish an emissions baseline. If this issue can be resolved, the British Columbia Forest Carbon Offset Protocol version 2 (FCOPv2) offers promise for developing verified carbon credits for three reasons: first, carbon (CO2), nitrous oxide (N2O), and methane (CH4), the three main GHG emissions from Indigenous fire management, are included in the protocol; second, credits under FCOPv2 are eligible for either compliance or voluntary markets, offering diversification; and third, a range of activities are eligible under the standard, including fire management and timber harvesting, which offers flexibility in terms of management practices. The Chilcotin project is likely to generate substantial co-benefits related to cultural, health and wellbeing, and livelihood values among First Nations participants. The Australian experience suggests that getting governance right, and building community ownership through “bottom-up” governance, is critical to the success of these programs. From the Australian model, community-based planning, like the Healthy Country Planning approach, can be a positive step to take, engaging community in goal setting for the program to guide and take ownership of its direction.

Core-shell structured ZnO nanorods enable flame-retardant, smoke suppressed and mechanically reinforced epoxy resin composites

The engagement of bio-based materials in the manufacture of flame-retardant has gained particular popularity in the past few years due to the raising environmental concerns. In this paper, a multifunctional nanoparticle (ZnO@TPB) that can confer flame-retardancy, mechanical enhancement and smoke suppression to epoxy resin (EP) is designed by constructing a shell layer containing bio-based materials (tannic acid) on the surface of zinc oxide (ZnO) nanorods. It is found that 10 wt% of ZnO@TPB can impart good flame-retardancy (UL-94 V-0 grade, LOI = 31% and 26.1% reduction in total smoke production (TSP)) and good mechanical properties (Young's modulus increased by 22.86%, hardness increased by 50.0% and storage modulus increased by 92.29%) to the modified EP. These desirable properties come from the multiple synergistic effects between ZnO and TPB. This research offered a viable tactic for the manufacture of EP with a low fire hazard.

Reference Data Accuracy Impacts Burned Area Product Validation: The Role of the Expert Analyst

Accurate reference data to validate burned area (BA) products are crucial to obtaining reliable accuracy metrics for such products. However, the accuracy of reference data can be affected by numerous factors; hence, we can expect some degree of deviation with respect to real ground conditions. Since reference data are usually produced by semi-automatic methods, where human-based image interpretation is an important part of the process, in this study, we analyze the impact of the interpreter on the accuracy of the reference data. Here, we compare the accuracy metrics of the FireCCI51 BA product obtained from reference datasets that were produced by different analysts over 60 sites located in tropical regions of South America. Additionally, fire severity, tree cover percentage, and canopy height were selected as explanatory sources of discrepancies between interpreters’ reference BA classifications. We found significant differences between the FireCCI51 accuracy metrics obtained with the different reference datasets. The highest accuracies (highest Dice coefficient) were obtained with the reference dataset produced by the most experienced interpreter. The results indicated that fire severity is the main source of discrepancy between interpreters. Disagreement between interpreters was more likely to occur in areas with low fire severity. We conclude that the training and experience of the interpreter play a crucial role in guaranteeing the quality of the reference data.

Comparison of different post-demolition autoclaved aerated concrete (AAC) recycling options

Autoclaved aerated concrete (AAC) is used as masonry blocks and prefabricated reinforced elements preferably in residential buildings. Due to its porous structure and mineral composition, it combines low thermal conductivity and fire resistance properties. Consequently, the popularity of AAC increases. However, due to significant AAC production volumes in many European countries since the 1960s and 1970s and given building lifetimes, strongly increasing post-demolition AAC waste volumes can be expected in the following decades. Recycling these post-demolition AAC wastes could protect primary resources and landfill capacities and reduce greenhouse gas emissions. But, recycling of post-demolition AAC is not yet established. The majority of the waste is landfilled even though landfill capacities have decreased and the legal framework conditions in Europe regarding a circular economy are becoming stricter. Therefore, new recycling options are needed. Current research approaches propose different open-loop recycling routes for post-demolition AAC, e.g. lightweight aggregate concrete, lightweight mortar, no-fines concrete, floor screed, animal bedding, oil- and chemical binders, and insulating fills for voids and interstitial spaces. Additionally, closed-loop recycling is possible and under research. Finely ground post-demolition AAC powder can be directly used in AAC production or can be chemically converted to belite (C2S) clinker to substitute primary cement in AAC production. These promising recycling options are compared regarding environmental and economic aspects. We find that the resource consumption is lower in all recycling options since post-demolition AAC helps to save primary resources. Furthermore, greenhouse gas emissions associated with the substituted primary resources are saved - especially when substituting primary cement in closed-loop recycling. In economic terms, increasing landfill costs could be avoided, which leaves a considerable margin for the cost of pre-processing, transport and recycling. The results can help decision-makers to implement circular management for AAC by fostering post-demolition AAC recycling and reducing its landfilling.

How do we sleep while our beds are burning? Impacts of the 2019–20 mega-fires on a rainforest dependent species – the Golden-tipped Bat Phoniscus papuensis

ABSTRACT The Australian summer of 2019/20 was impacted by megafires of a magnitude and severity never previously recorded. Whilst low severity fire has positive benefits for increased insectivorous bat activity and diversity, little information is available on the impact on rainforest specialised clutter dependant species such as the Golden-tipped Bat Phoniscus papuensis. Our aims were to assess the effects of fire on occupancy of habitat across the geographic range of P. papuensis in NSW, to determine the smaller scale effects of fire on use of diurnal roosts in rainforest through radio tracking and to trial the use of artificial structures to temporarily increase roost availability in burnt habitat. We observed that widespread fire encroaching on rainforest has a negative association with occupancy by P. papuensis, with this metric ~78% lower than in unburnt forest. In burnt areas, P. papuensis preferentially used unburnt refugia for their roosting sites in suspended bird nests and the loss of these habitat structures likely contributes to the disappearance of P. papuensis from the landscape. Artificial roosts were not used in the short-term (< 2 years post fire) and do not appear to be a feasible management tool. With the increasing frequency and extent of wildfires the most important factor for P. papuensis to persist in the landscape into the future is the protection of its habitat through ensuring sensitive management of large tracts of connected rainforest to help buffer against the encroachment of future mega-fires.

Factors Influencing Risk during Wildfires: Contrasting Divergent Regions in the US

(1) Background: Federal land managers in the US are charged with risk-based decision-making which requires them to know the risk and to direct resources accordingly. Without understanding the specific factors that produce risk, it is difficult to identify strategies to reduce it. (2) Methods: Risk characterized by U.S. land managers during wildfires was evaluated from 2010–2017 to identify factors driving risk perceptions. Annotation from 282 wildfires in two regions with distinctive risk profiles, the Northwest and Southwest Geographic Areas, were qualitatively coded using the risk assessment framework of hazards, values, and probability from the Relative Risk Assessment in the Wildland Fire Decision Support System (WFDSS). (3) Results: The effects of climate on seasonal severity, fuel condition, and fire behavior emerged as the most influential factors driving risk perceptions and characterizations of risk in both regions. Monsoonal precipitation extended the longevity of landscape barriers, especially in the Southwest. The results suggest that a scarcity of values at risk and a mild fire environment produce low risk fires regardless of location, while high risk fires reflect specific local values and geography, under the umbrella of dry climate. (4) Conclusions: the climatic contrasts between the two regions highlight how influential climate change will be on future characterizations of wildfire risk.

Exploring the factors influencing the hydrological response of soil after low and high-severity fires with post-fire mulching in Mediterranean forests

Despite ample literature, the influence of the individual soil properties and covers on the hydrological response of burned soils of forests has not clearly identified. A clear understanding of the surface runoff and erosion rates altered by wildfires and prescribed fires is beneficial to identify the most suitable post-fire treatment. This study has carried out a combined analysis of the hydrological response of soil and its driving factors in burned forests of Central-Eastern Spain. The pine stands of these forests were subjected to both prescribed fire and wildfire, and, in the latter case, to post-fire treatment with mulching. Moreover, simple multi-regression models are proposed to predict runoff and erosion in the experimental conditions. In the case of the prescribed burning, the fire had a limited impact on runoff and erosion compared to the unburned areas, due to the limited changes in soil parameters. In contrast, the wildfire increased many-fold the runoff and erosion rates, but the mulching reduced the hydrological response of the burned soils, particularly for the first two-three rainfalls after the fire. The increase in runoff and erosion after the wildfire was associated to the removal of the vegetation cover, soil water repellency, and ash left by fire; the changes in water infiltration played a minor role on runoff and erosion. The multi-regression models developed for the prescribed fire were accurate to predict the post-fire runoff coefficients. However, these models were less reliable for predictions of the mean erosion rates. The predictions of erosion after wildfire and mulching were excellent, while those of runoff were not satisfactory (except for the mean values). These results are useful to better understand the relations among the hydrological effects of fire on one side and the main soil properties and covers on the other side. Moreover, the proposed prediction models are useful to support the planning activities of forest managers and hydrologists towards a more effective conservation of forest soils.

Roost Selection in Relation to a Patchy, Mosaic Management Burn by a Threatened Clutter-Adapted Bat

Fire is a major disturbance for forests and its impacts can be complex, influenced by a range of factors including fire severity and frequency. Changes to global climate have increased the frequency and lengthened the window for wildfires. Anthropogenic fires are now commonly used to try to mitigate the risk and spread of wildfires or for ecological purposes, yet it is unclear how many flora and fauna species respond to this lower severity and more patchily distributed treatment. We assessed day-roost selection by a threatened narrow space bat, Nyctophilus corbeni, after a management burn left a mosaic of unburnt forest, low severity (ground scorch) burnt and higher severity (midstorey to crown scorch) burnt forest. Radio-tracking was used to identify day-roosts of 11 individuals (8 lactating females and 3 males) during the maternity season. Characteristics of day-roost trees (n = 42 trees) were similar for males and lactating females and were comparable to other day-roosts used elsewhere in the broader study area, with bats selecting moderately sized (23–24 cm dbhob) dead buloke (Allocasuarina luehmannii) with hollows. However, roost selection at the scale of the neighborhood varied by sex and was random for lactating females. Selection of the post-burn mosaic by males was non-random at all scales of assessment greater than a 100 m neighborhood, with bats selecting areas burnt by low-severity fire at these scales, but avoiding areas of higher severity fire. Locally, there were ~14 more hollow trees per ha surrounding roosts in areas burnt by low severity fire than in the unburnt forest, whereas forest burnt by higher severity fire had on average ~8 fewer hollow trees per hectare. Our study confirmed that dead buloke with hollows is a key resource for N. corbeni that should be prioritized for retention, particularly when identifying areas to offset habitat loss. Patchy management fires appear to be compatible with roosting habits of breeding N. corbeni, provided hollow resources are not impacted by fire. Management burns may promote roosting habitat for male bats, but areas of higher severity burns need to be minimized. Further research is needed to assess the use of the post-burn mosaic for nightly movements, including foraging. The effects of repeated burning on hollow availability and roost selection by N. corbeni should be investigated to identify suitable intervals between fires for this threatened species.

Fire severity has lasting effects on the distribution of arboreal mammals in a resprouting forest

AbstractWildfire severity is assumed to be an important driver of habitat availability and species' distributions in forest ecosystems. Many studies have focused on the immediate or short‐term effects of fire severity in fire‐prone ecosystems, with much less focus on how long the effect of fire severity may persist. We examined the effect of fire severity on the distribution of arboreal mammals at 3 and 10 years post‐fire, in a temperate forest ecosystem dominated by eucalypts that have strong resistance and resilience to low and high severity fire, respectively. The study took place within areas affected by the 2009 Kilmore East‐Murrindindi wildfires in south‐eastern Australia. Sites were established across a gradient of fire severity (unburnt through to canopy consumption) and surveyed at 3 and 10 years following fire. Owing to low detection rates for many species, analyses were limited to greater glider (Petauroides volans) occurrence and arboreal species richness. At both 3 and 10 years post‐fire, the greater glider was restricted to unburnt forest or sites affected only by understorey fire, which acted as fire refugia. Greater gliders were absent from sites affected by high severity, canopy‐consuming fires at both points in time. Greater glider occurrence was associated with high levels of canopy cover (>50%), which were typically those areas that were unburnt or burnt at low severity. The richness of arboreal mammals increased over time and was greater in unburnt or minimally affected forest. Our findings emphasize: (i) that fire severity is an important driver of the distribution of arboreal mammals; and (ii) the importance of recognizing longer‐term effects of fire severity in assessing species distributions, even in highly resilient forest communities. Recent advances in mapping fire severity provide new opportunities to assess the effects of fire severity on the distributional patterns of fauna in eucalypt forests.

Merging prescribed fires and timber harvests in the Sierra Nevada: Burn season and pruning influences in young mixed conifer stands

In dry, productive forests where historically infrequent high-severity fires are now common, new silvicultural systems will be needed to better align management activity with the ecosystem's dependent disturbance regime of frequent low and moderate-severity fires. Merging timber harvests with prescribed fire programs can be advantageous because each disturbance provides benefits that the other cannot provide alone. We conducted a study aimed at providing information to managers interested in merging gap-based silviculture with frequent prescribed fire. We studied the influence of burn season (spring versus fall) on canopy mortality and damage by conducting prescribed burns in 13-14 year old stands that had been regenerated with gap-based silviculture. We also pruned sugar pine (Pinus lambertiana) and incense-cedar (Calocedrus decurrens) prior to burns to evaluate the influence of pruning on fire related mortality and damage. Fall (21%) and spring (19%) burns resulted in similar amounts of mortality two years following burns, but the fall burns consumed considerably more fuel compared to spring burns. Percent volume crown scorch was greater in spring burns and greater when crown bases were low to the ground. Fall burns were generally favorable assuming a management context where fuel consumption and survival is desirable. However, either burn season may be acceptable using fire as a thinning mechanism is desired to encourage the development of low-density, mature stands. As a pre-fire treatment, pruning did not clearly reduce fire-related mortality or crown damage. Considering that pruning itself is a form of crown damage, it could be considered counterproductive as a pre-fire treatment because of increased heat entering pruned crowns as a result of increased surface fuel and the loss of heat-buffering lower branches. Merging gap-based silviculture with prescribed fires in perpetuity may be initially complex operationally in the Sierra Nevada, but it offers managers a disturbance regime-guided method for sustaining heterogeneity at fine and coarse scales while maintaining low surface fuels. The timing of introducing fires into young stands as well as traditional timber management tools such as rotation ages and harvest intervals can be altered depending on exact objectives.

Interactions among wildfire, forest type and landscape position are key determinants of boreal forest carbon stocks

Abstract Boreal forest soils contain large stocks of soil carbon (C) that may be sensitive to changes in climate and disturbance. Destablization of boreal forest soil C through changes in C inputs, belowground C pools and/or wildfire could feedback to accelerate rising atmospheric CO2 concentration. Additionally, increasing frequency of severe fires may be changing the dominant forest types and reshaping aboveground C stocks. Although controls on ecosystem C pools have received considerable attention, many studies have been limited to locations near the road system, leading to uncertainty in current and future C stocks across boreal Alaska. Here, we leveraged 545 randomly selected and spatially balanced Forest Inventory and Analysis (FIA) plots across ~13.5 million hectares in interior Alaska to examine the factors governing soil and live tree C pools. Forest type mediated the effects of mean summer air temperature and the probability of near‐surface permafrost on soil C. Meanwhile, forest type, stand age and aspect were the primary drivers of live tree C. Overall, plots with a known history of wildfire during the past 70 years did not have significantly different soil C stocks than plots without a known history of fire, likely due to the historical predominance of low severity fires. Where wildfire likely initiated a transition to deciduous trees (19% of plots), live tree and soil C pools were reduced by 16% and 20%, respectively. Ecosystem C likely recovered over time, as maturing deciduous stands rapidly gained C in live trees. Deciduous stands without a known fire had comparatively very large live tree C stocks, suggesting a significant change in the distribution of ecosystem C following severe fire. Synthesis. Our results highlight the nuanced interactions among wildfire, landscape position and forest type that will play important roles in shaping future boreal ecosystem C stocks.

Impact of forest fire frequency on floristic diversity in the forests of Uttarakhand, western Himalaya

The Uttarakhand State of India is rich in forest wealth with 45.4% forest cover (India State of Forest Report (2021). However, forest cover may change due to a number of anthropogenic and environmental factors. One of the factors leading to forest degradation is forest fires. Forest fires are related to factors that may be biotic, such as heavy accumulation of Chir pine (Pinus roxburghii, a dominant forest forming tree) needles on the forest floor influencing fuel load accumulation and flammability, or abiotic, such as climate, topography, or soil type influencing fuel moisture and fire spread. This study was carried out using satellite images of study area where fire was classified using the geographical information system (GIS) into four frequency classes (no fire, low fire, moderate fire, and high fire). We sampled a total of 160 quadrates for trees, 320 for shrubs and 480 for herbaceous plants to assess vegetation diversity for each forest fire frequency class. No fire was recorded for 13,619 sample points, which covers an area of 84% of the study area, whereas low fire frequency was recorded for 1784 sample points covering an area of 11%. In the present study, significant differences in species diversity were observed across the fire frequency classes. While species diversity increased in the low fire frequency class, an increase in fire frequency led to a decline in diversity and increased dominance of certain fire-tolerant species. Our results show that species richness and density decreased in higher fire frequency classes, which could be due to a poor regeneration process. We found that tree species diversity was higher for the low fire frequency class, followed by moderate fire frequency class, no fire frequency class, and was lowest for the high fire frequency class. The diversity of herbs decreased with increasing fire frequency, from a minimum of 12 species in the high fire frequency class to a maximum of 37 in the no fire frequency class. Some of the fire-adapted species were Myrica esculenta, Pyrus pashia, Lyonia ovalifolia, Carissa spinarum, Pyracantha crenulata, Desmodium microphyllum, and Micromeria biflora the regeneration of which should be promoted rehabilitate the fire damage forest ecosystem of Uttarakhand.

The Analyses of Forest Fire Vulnerability at Taman Hutan Raya (Tahura) Nipa-Nipa Kendari City

Forest fires are one of the environmental problems that recur almost every year in Indonesia. This problem if not handled properly will certainly cause various negative impacts such as the emergence of haze that can interfere with public health and reduced forest cover, in forest areas. Taman Hutan Raya Nipa-Nipa (Tahura) as one of the Natural Preservation areas of Southeast Sulawesi Province is also inseparable from the problem of forest fires. The aims of the study were to analyze the level of forest fire vulnerability in the Tahura Nipa-Nipa area, especially in Watu-Watu Village, West Kendari Subdistrict, and the variables that most affect the level of forest fire vulnerability. Data analysis based on the weighting of each element is then carried out the determination of the vulnerability class using equations: forest fire vulnerability = {30 % x (land cover)} + {(20 % x height of place)} + {(20 % x Rainfall)} + {(10 % x distance from road)} + {(10 % x distance from river)} + {(10 % x distance from settlement)}. Mapping the class of forest fire vulnerability areas using geoprocessing with input data on land cover, place height, rainfall, and distance from roads, rivers, and settlements. Then an analysis is carried out and will be selected data according to the score of the level of forest fire vulnerability, namely very low/not a vulnerability with a score of 5, low with a score of 4, medium with a score of 3, high with a score of 2, very high /very vulnerability with a score of 1. The results showed that the level of forest fire vulnerability in Tahura Nipa-Nipa has 3 levels, namely the level of high forest fire vulnerability with an area of 68.51 ha, the level of moderate forest fire vulnerability with an area of 62.29 ha, and the level of low fire vulnerability with an area of 143.35 ha. The variables that most affect the level of forest fire vulnerability at the research site are land cover and community accessibility distance in the form of distance from the road and distance from the settlement.