Fire Episodes Research Articles

Forest Fire Induced Air Pollution over Eastern India during March 2021

Being a significant contributor to atmospheric CO2, forest fires are considered a threat to the terrestrial ecosystems that influence climate change. This study integrates in-situ and earth observation platforms to investigate an episodic forest fire event at the Similipal National Park and the adjacent areas in eastern India and its effect on the ambient atmosphere of the nearby areas in 2021 March. The analysis brings out a substantial rise in the Aerosol Optical Depth (AOD) during this period with apparent anomalies in carbon monoxide (CO) and ozone (O3). The pronounced increase in the surface concentration of PM2.5 was increased about 12 µg m–3. Furthermore, the AOD exhibited a spike of about 56.21% during the fire episode. The pollutants' intensity (except NO2) was directly proportional to the fire counts, translated across the northern part of the region. The study also employed an emission index to calculate the amount of CO2 emitted and was pressed against changes in atmospheric XCO2 concentrations retrieved from OCO-2 during the fire episode.

Dynamics of paleo-fires in the forest-steppe zone of the Western Siberia

Abstract. In this work we present the results of reconstruction of the dynamics of paleo-fires over the last 3300 cal. yr BP in the Barabinsk forest-steppe of the Western Siberia based on macrocharcoal analysis and radiocarbon dating of peat deposits of the Nikolaevsky ryam. The authors identified 18 local fire episodes using the CharAnalysis program. At the end of the Subboreal period, 6 local fires occurred, probably caused by dry and cold conditions. In the subAtlantic period of the Holocene, 12 fires were recorded with a peak of pyrogenic activity at 1200-1000 cal. yr BP. This peak of fires is probably associated with the warm and dry conditions of the Medieval Climate Optimum. As a result of the study, it was concluded that the intensity and frequency of paleo-fires in the area of Nikolaevsky ryam were influenced by climatic changes: in dry climatic periods, an increase in fire activity was observed.

New open burning policy reshaped the aerosol characteristics of agricultural fire episodes in Northeast China

The massive agricultural sector in the Northeast Plain, which is of great importance for the food security in China, results in a huge amount of crop residues and thus substantial concern on haze pollution due to biomass burning (BB). To seek for effective control measures on BB emissions, a dramatic transition of open burning policy occurred in Heilongjiang Province, from the “legitimate burning” policy released in 2018 to the “strict prohibition” policy implemented in 2019 and beyond. Here we explored the BB aerosols during 2020–2021 in Harbin, the capital city of Heilongjiang. Although open burning was strictly prohibited by mandatory bans, agricultural fires were not actually eliminated, as indicated by the levoglucosan levels and fire count results. In general, the BB aerosols in Harbin were attributed to the overlaying of household burning and agricultural fire emissions. The former factor laid the foundation of biomass burning impacts, with BB contributions to organic carbon and elemental carbon (fBBOC and fBBEC) of 35 and 47%, respectively. The latter further enhanced the BB impacts during specific episodes breaking out in the spring of 2021 as well as the fall of 2020, when fBBOC and fBBEC increased to 64 and 57%, respectively. In addition, comparing to the fires of 2018–2019 which occurred in winter (in response to the “legitimate burning” policy), the agricultural fires were shifted to spring and fall in the 2020–2021 campaign, accompanied with an increase of combustion efficiency. This study illustrated how the agricultural fire emissions were influenced by the transition of open burning policy.

Late Holocene climate variability in central Korea indicated by vegetation, geochemistry, and fire records of the Yongneup moor

In many cases, proxy-based palaeoclimatic and palaeoenvironmental reconstructions in East Asia have shown mixed signatures of summer temperature and precipitation, driven by the predominant regional impact of the East Asian Summer Monsoon. Although these studies have contributed significantly to understanding the past variability in East Asian summer climate during the Holocene period, relatively little has been learned about climatic conditions in other seasons, such as winter and spring, and variations in the individual climatic elements of temperature and precipitation. To address these issues, in this study, we present a reconstruction of a 3000-year fire and vegetation history of the Yongneup moor, central Korea, during the late Holocene based on multi-proxy analyses of pollen, geochemistry, and macrocharcoal. Our data identify two fire episodes at Yongneup during ca. 2900–2700 and 2400–2300 cal yr B.P., possibly caused amid deteriorated climatic conditions not only in summer but also in winter–spring during contemporaneous grand solar minima. During the last two millennia, Yongneup likely experienced cold weather conditions at ca. 1420–1230 and 1000–590 cal yr B.P. and warm conditions at ca. 1850–1420 and 1230–1000 cal yr B.P., as well as wet conditions during ca. 1530–1400, 1220–1000, and 890–700 cal yr B.P. and drier conditions during ca. 1750–1530, 1400–1220, 1000–890, and 700–530 cal yr B.P. The dry periods were coincident with an increased El Niño–Southern Oscillation in the Tropical Pacific Ocean, which supports its role in controlling the hydroclimate of the Korean Peninsula. Our results also emphasise the potential value of further research on the “Millennium Eruption” of Mount Paektu/Changbaishan (946 CE), whose climatic consequences in the East Asian region remain poorly understood. • Late Holocene climate variability in Korea reconstructed from the Yongneup moor • Fire events coincident with solar minima at ca. 2900–2700 and 2400–2300 cal yr B.P. • Potential impact of climate deterioration on Mumun (Bronze Age) societies in Korea • Fluctuations in cold–warm and dry-wet conditions during the last two millennia • Implication on the volcanic impact of the “Millennium Eruption” of Mount Paektu

Late Glacial and Holocene buried black soils in Emilia (northern Italy): genetic and paleoenvironmental insights

PurposeThe existence of black horizons (BHs) is often highlighted in European soils, and in the Po River plain of northern Italy. Nevertheless, BH chronological frameworks and genetic models are still debated. The present study investigated the genesis of BHs in the eastern Po Plain where they are buried at various depths.Materials and methodsSoil sequences were investigated with a multidisciplinary approach integrating geomorphologic, stratigraphic, pedologic, geochemical, isotopic, palynological, and radiometric analyses.Results and discussionThe formation of the studied BHs was scattered over time from the Last Glacial Maximum to at least the middle Holocene. The new data indicate that BHs developed when the landscape was dominated by coniferous forest during conditions that were totally different from the current pedoclimatic setting. The recurrent presence of black particles indicates that this vegetation cover was systematically affected by fire episodes that induced soil degradation and mineralization processes of the original organic compounds, thus contributing to darkening of the upper soil horizons.ConclusionsBH formation clearly coincided with cold time lapses. Evidence for repeated fire events (natural or human-induced?) provides insights for the controversial debate on early anthropogenic impacts on the environment.

Fire in Semi-Arid Shrublands and Woodlands: Spatial and Temporal Patterns in an Australian Landscape

Semi-arid landscapes are of interest to fire ecologists because they are generally located in the climatic transition zone between arid lands (where fires tend to be rare due to lack of fuel, but are enhanced following large rainfall episodes) and more mesic regions (where fire activity tends to be enhanced following severe rainfall deficits). Here we report on the characteristics of the contemporary fire regimes operating in a semi-arid region of inland south-western Australia with rainfall averaging around 300 mm per annum. To characterize fire regimes, we analyzed a geodatabase of fire scars (1960–2018) to derive fire preferences for each major vegetation type and fire episode and used known fire intervals to model fire hazard over time and calculate typical fire frequencies. We also used super epoch analysis and correlations to explore relationships between annual fire extent and rainfall received before the fire. We found fires strongly favored sandplain shrublands, and these tended to experience hot crown fires once every 100 years (median fire interval), with fire hazard increasing linearly over time. In contrast, fires were rare in eucalypt woodland and other vegetation types, with a median interval of 870 years and broadly consistent fire hazard over time. Annual fire extent was most strongly linked with high rainfall in the year prior to fire, and this was particularly so for eucalypt woodlands. Large-scale fires in shrublands tended to favor areas burnt in previous large fires, whereas in woodlands they favored edges. In conclusion, we found divergent fire regimes across the major vegetation types of the region. Sandplain shrublands were similar to Mediterranean shrublands in that they experienced intense stand-replacing wildfires which recovered vigorously although slowly, meaning burnt shrublands did not experience fires again for at least 25 and 100 years on average. In contrast, eucalypt woodlands were fire sensitive (trees readily killed by fire) and experienced fires mostly around the edges, spreading into core areas only after large rainfall events elevated fuel levels. Overall, both vegetation types subscribed to typical arid-zone fire regimes where elevated rainfall, and not drought, promoted fires, although the role of fuel accumulation over time was more important in the shrublands.

Maximum entropy-based forest fire likelihood mapping: analysing the trends, distribution, and drivers of forest fires in Sikkim Himalaya

ABSTRACT The recent episodes of forest fires in Brazil and Australia of 2019 are tragic reminders of the hazards of forest fire. Globally incidents of forest fire events are on the rise due to human encroachment into the wilderness and climate change. Sikkim with a forest cover of more than 47%, suffers seasonal instances of frequent forest fire during the dry winter months. To address this issue, a GIS-aided and MaxEnt machine learning-based forest fire prediction map has been prepared using a forest fire inventory database and maps of environmental features. The study indicates that amongst the environmental features, climatic conditions and proximity to roads are the major determinants of forest fire. Model validation criteria like ROC curve, correlation coefficient, and Cohen's Kappa show a good predictive ability (AUC = 0.95, COR = 0.81, κ = 0.78). The outcomes of this study in the form of a forest fire prediction map can aid the stakeholders of the forest in taking informed mitigation measures.

Long-term trends of PM2.5 and its carbon content in the South Coast Air Basin: A focus on the impact of wildfires

Implementation of stringent regulations on stationary and mobile sources at the local, state, and federal levels over the past two decades resulted in a substantial reduction of mass concentrations of ambient fine particulate matter (PM2.5) and its carbonaceous content including elemental carbon (EC) and organic carbon (OC) in California's South Coast Air Basin (SCAB). PM2.5, EC, and OC from sources that cannot reasonably be controlled through regulations, such as wildfires, are gaining more significance as emissions from anthropogenic sources are reduced. Among other factors, dry conditions and forest management practices in recent decades have also contributed to increased frequency and intensity of wildfire events in California, including the SCAB, and these emissions may offset expected air quality improvements due to decreases in anthropogenic emissions. We examined PM2.5 measurements to determine if wildfire emissions had impacted trends of PM2.5 and its carbonaceous fraction in the SCAB.In this work, we analyzed the long-term trends of PM2.5, EC, and OC at four sites in urban regions of the SCAB, as well as four sites in the surrounding remote areas from 2004 to 2018. The results showed that the annual concentrations were reduced across all sites with larger reductions at the urban sites compared to the remote regions. PM2.5 was reduced 31–51% in the urban and 12–35% in the remote sites. In the urban sites, EC and OC concentrations increased from 2004 to 2007 and were followed by a decline of over 50%. In the remote sites, EC peaked in 2005 with a decline afterward resulting in total reductions of 28–45%, while the OC levels were modestly reduced by 7–23%.Using a back-trajectory model combined with a fire emission inventory, we identified the days that were potentially affected by wildfires as “fire days” and compared them to the rest of the study period. The results suggest that while wildfires led to higher concentrations of PM2.5 and its carbonaceous fractions during the days impacted by fire episodes, their impacts on long-term trends or overall concentration averages were not statistically significant in the urban regions where the anthropogenic sources are dominant. However, wildfires had important impacts on PM2.5 levels in the remote sites and excluding the fire days resulted in statistically significant reductions in concentration levels.Also, OC/EC ratio was analyzed as an indicator for the contribution of wildfires and secondary organic carbon (SOC). Higher OC/EC ratios indicate larger contributions from wildfire and SOC sources compared with lower OC/EC ratios are more reflective of anthropogenic combustion emissions. While this ratio did not have an increasing or decreasing trend in the urban region, average OC/EC changed from 4.8 in 2004 to 6.9 in 2018 with a statistically significant increasing trend in the remote sites. This suggests the contribution of wildfire and secondary organic carbon sources are increasing in the remote regions of SCAB while the change in their contribution in the urban sites is statistically insignificant.

Indigenous Fire-Managed Landscapes in Southeast Australia during the Holocene—New Insights from the Furneaux Group Islands, Bass Strait

Indigenous land use and climate have shaped fire regimes in southeast Australia during the Holocene, although their relative influence remains unclear. The archaeologically attested mid-Holocene decline in land-use intensity on the Furneaux Group islands (FGI) relative to mainland Tasmanian and SE Australia presents a natural experiment to identify the roles of climate and anthropogenic land use. We reconstruct two key facets of regional fire regimes, biomass (vegetation) burned (BB) and recurrence rate of fire episodes (RRFE), by using total charcoal influx and charcoal peaks in palaeoecological records, respectively. Our results suggest climate-driven biomass accumulation and dryness-controlled BB across southeast Australia during the Holocene. Insights from the FGI suggest people elevated the recurrence rate of fire episodes through frequent cultural burning during the early Holocene and reduction in recurrent Indigenous cultural burning during the mid–late Holocene led to increases in BB. These results provide long-term evidence of the effectiveness of Indigenous cultural burning in reducing biomass burned and may be effective in stabilizing fire regimes in flammable landscapes in the future.

Growth and survival over ten years of Brazil-nut trees planted in three anthropogenic habitats in northern Amazonia

ABSTRACT We examined the growth and survival of Brazil-nut trees, Bertholletia excelsa (Lecythidaceae) under different environmental conditions and levels of canopy openness within experimental plantations in the Trombetas River valley, in northern Brazil. We planted 144 seedlings in three anthropogenic habitats with different levels of sunlight exposition: crop field (100% canopy opening), shrub fallow (20-80% canopy opening) and Brazil-nut forest (< 10% canopy opening). We measured plant height and diameter annually and recorded mortality and resprouting over ten years. The performance of B. excelsa differed significantly among habitats, with the highest growth rate observed at the highest level of canopy openness (crop field). Survival was highest in crop field (85%) and shrub fallow (63%) and lowest in Brazil-nut forest (17%). Resprouting capacity was higher in the crop field, as Brazil-nut plants recovered after fire episodes, with most plants resprouting more than one shoot. Some trees in the crop field began to produce flowers and fruits at 9-10 years. We showed that B. excelsa juveniles are light-demanding, with higher survival and growth under conditions of high light exposure. We suggest the use of Brazil-nut trees for reforestation, restoration of degraded lands and enrichment of secondary vegetation, as long as an adequate management is adopted (e.g., maintaining plants exposed to direct sunlight and control of competing pioneer species).

Effects of biomass burning on chlorophyll-a concentration and particulate organic carbon in the subarctic North Pacific Ocean based on satellite observations and WRF-Chem model simulations: A case study

In recent years, the impact of aerosols on marine ecology has received increasing attention. However, the research on this aspect mainly focuses on the aspect of dust aerosols. As an important source of dissolved iron (Fe) and carbon in the ocean, biomass burning aerosol deposition has an extremely important impact on Marine ecosystem. In this study, a forest fire episode was investigated using satellite observations and the WRF-Chem model from 23 to 26 April 2014. Particular attention was paid to the biomass burning effects on the particulate organic carbon (POC) and chlorophyll-a (Chl-a) concentration in the subarctic North Pacific Ocean (SNPO). The geopotential height and CALIPSO results indicated that smoke (biomass burning) aerosols were transported from Northeast Asia to the SNPO in 2 days with the effect of a low-pressure system in Mongolia. The WRF-Chem model also confirmed that CO spread southeastward and reached the SNPO in two days. Wet deposition of smoke aerosols occurred over the research region (RR) (40°-50°N, 150°-160°E) in the SNPO from 25 to 26 April 2014, and both the Chl-a concentration and POC over the RR increased nearly five times one day after the deposition of smoke aerosols. These significant increases were one order of magnitude higher than those that occurred in response to the dust episode, and the time delay was also shorter. This result indicates that smoke aerosols emitted by biomass burning lead to an increase in phytoplankton and POC once deposited and dissolved in the surface ocean, biomass burning emissions may have a more important effect in marine productivity and even ocean carbon cycles for some high nutrient and low chlorophyll (HNLC) regions compared with dust aerosols.

Estimating Greenhouse Gas Emissions From Peat Combustion in Wildfires on Indonesian Peatlands, and Their Uncertainty

AbstractPeatlands play an important role as carbon pools, storing a third of the world's soil carbon. However, peatlands in Southeast Asia have suffered from depletion due to economic pressure and the demand for natural resources, often caused by land use changes and fires. Usually, land preparation requires drainage and fires, resulting in major greenhouse gas (GHG) emissions into the atmosphere. In this work, we propose a general equation to estimate GHG emissions from fires on peatlands. The contribution of each parameter to the variance of the estimated GHG emissions was also evaluated. We used Monte Carlo simulation, meta‐analyses, and an analytical expression of variance. GHG emissions of a single fire episode were estimated at 842 Mg ha−1 CO2 eq. with a standard deviation of 466 Mg ha−1 CO2 eq. The parameter contributing most to variance was the depth of burn, at 94.2%, followed by bulk density, at 5.5%, and emission factors, at 0.3%. Our estimated GHG emissions were close to the amount estimated from the default values provided by the IPCC, strengthening confidence in the IPCC methodology. When the depth of burn was assessed by remote sensing, the parameter that most contributed to variance became the fire‐damaged area, followed by the depth of burn. The contribution of each parameter to variance, as estimated in this study, made it possible to prioritize the effort in uncertainty reduction. Combining Monte Carlo simulation and an analytical expression of variance could be a promising way of obtaining more reliable confidence intervals.

Holocene fire history reconstruction of a mid-elevation mixed-conifer forest in the Eastern Cascades, Washington, USA

Fire histories of mid-elevation mixed-conifer forests are uncommon in the eastern Cascades, limiting our understanding of long-term fire dynamics in these environments. The purpose of this study was to reconstruct the fire and vegetation history for a moist mid-elevation mixed-conifer site, and to determine whether Holocene fire activity in this watershed was intermediate to fire regimes observed at higher and lower elevations in the eastern Cascades. Fire activity and vegetation change was reconstructed using macroscopic charcoal and pollen analysis of sediment core from Long Lake. This site is located ~45 km west of Yakima, WA, and exists in a grand fir-dominated, mixed-conifer forest. Results show low fire activity from ca. 9870 to 6000 cal yr BP, after which time fire increased and remained frequent until ca. 500 cal yr BP. A woodland environment existed at the site in the early Holocene, with the modern coniferous forest establishing ca. 6000–5500 cal yr BP. A mixed-severity fire regime has existed at the site for the past ~6000 years, with both higher- and lower-severity fire episodes occurring on average every ~80–100 years. However, only one fire episode occurred in the Long Lake watershed during the past 500 years, and none within the past ~150 years. Based on a comparison with other eastern Cascade sites, Holocene fire regimes at Long Lake, particularly during the late Holocene, appear to be intermediate between those observed at higher- and lower elevation sites, both in terms of fire severity and frequency.

Top-Down Estimation of Particulate Matter Emissions from Extreme Tropical Peatland Fires Using Geostationary Satellite Fire Radiative Power Observations.

Extreme fires in the peatlands of South East (SE) Asia are arguably the world’s greatest biomass burning events, resulting in some of the worst ambient air pollution ever recorded (PM10 > 3000 µg·m−3). The worst of these fires coincide with El Niño related droughts, and include huge areas of smouldering combustion that can persist for months. However, areas of flaming surface vegetation combustion atop peat are also seen, and we show that the largest of these latter fires appear to be the most radiant and intensely smoke-emitting areas of combustion present in such extreme fire episodes. Fire emissions inventories and early warning of the air quality impacts of landscape fire are increasingly based on the fire radiative power (FRP) approach to fire emissions estimation, including for these SE Asia peatland fires. “Top-down” methods estimate total particulate matter emissions directly from FRP observations using so-called “smoke emission coefficients” [Ce; g·MJ−1], but currently no discrimination is made between fire types during such calculations. We show that for a subset of some of the most thermally radiant peatland fires seen during the 2015 El Niño, the most appropriate Ce is around a factor of three lower than currently assumed (~16.8 ± 1.6 g·MJ−1 vs. 52.4 g·MJ−1). Analysis indicates that this difference stems from these highly radiant fires containing areas of substantial flaming combustion, which changes the amount of particulate matter emitted per unit of observable fire radiative heat release in comparison to more smouldering dominated events. We also show that even a single one of these most radiant fires is responsible for almost 10% of the overall particulate matter released during the 2015 fire event, highlighting the importance of this fire type to overall emission totals. Discriminating these different fires types in ways demonstrated herein should thus ultimately improve the accuracy of SE Asian fire emissions estimates derived using the FRP approach, and the air quality modelling which they support.

Assessment of the Influence of Pyrogenic Factors on the Biological Properties of Chernozems

Changes in the biological properties of chernozems caused by several pyrogenic agents have been studied in simulation experiments with the low-temperature plasma, infrared irradiation, straw burning, and fume of burning products. It has been shown that the pyrogenic effect has a complex nature, so that worsening of biological parameters depends on temperature, duration of fire episode, intensity of fume, ash impact, and soil moisture. Such integrated effect induced a decrease in microbial biomass by 39%, population of nitrogen-fixating bacteria by 29% versus the control values. The inhibition of dehydrogenase and catalase (oxidoreductase class) was 44–53%; the activity of hydrolase (phosphatase and invertase) was lower (by 16–18%). A maximal effect was recorded for the uppermost soil layer (0–1 сm) as compared to the lower 4–5 сm layer. Microbiological indices went down by 52–56% after placing the sample in the flame of a gas burner for 3 minutes, while soil enzyme activity decreased by 25–26%. For the latter, the duration of flame effect was of special importance; the correlation coefficient for dehydrogenase activity was –0.81; for invertase activity, –0.86; for catalase activity, –0.78; and for phosphatase activity, –0.85 (р < 0.01). Increasing IR irradiation also resulted in growing inhibition of biological indices. Even a minimal impact of fume of straw burning products (3 minutes at temperature 52°С) reliably decreased soil microbiological and biochemical parameters (by 4–19%, р < 0.05). Higher level of impact suppresses the biological activity by 20–30%.

Fire, flood and monodominance of Tabebuia aurea in Pantanal

Environmental filters affect species diversity. Understanding their influence on plant communities is one of the main challenges of ecology in the search for solutions to the management and conservation of floodable savannas. To shed more light on this challenge, the present work asked if the interactions between flood and fire influence the richness of community and favor the abundance and basal area of the monodominant Pantanal species Tabebuia aurea. We also asked what role earth-mounds play in this process. To address these questions, we used Landsat-5 and -8 and Resourcesat-1 satellite data; to access the fire history in monodominant stands of T. aurea in the Pantanal from 2003 to 2017. We chose 37 areas with 2 to 9 annual fire episodes. A total of 125 25 × 25 m plots were established in the different areas, to sample arboreal strata. We sampled all individuals ≥3.18 cm in diameter at breast height (dbh). In each plot, we measured height by the watermark from the last flooding on each individual as a proxy of inundation level. We applied generalized linear model (GLM) analyses to compare effects of flood and fire on abundance, richness and basal area, on and off earth-mounds using negative binomial, Poisson and Gaussian distribution, respectively. We sampled 2411 individuals distributed among 19 families, 31 genera and 36 species. Under higher fire frequency, abundance, richness and basal area of all species decreased with increase of water level. However, the abundance and basal area of Tabebuia aurea remained higher than those of other species. Under lower fire frequency, the abundance and richness of all species in the community increased with water level. Basal area, however, decreased with increasing water level, such that individuals with larger basal area were found under lower fire frequency. Under high fire frequency earth-mounds protected T. aurea individuals from fire and flood. Earth-mounds influenced species richness and basal area only under medium-low fire frequency. Results show that monodominance of T. aurea benefits from the interaction between fire and flood, with some help from earth-mounds. Individuals of other tree species, show tolerance to high flood levels or high fire frequencies, but not the interaction between fire and flood. This dynamic strengthens the monodominance of T. aurea, as the number of individuals also increases. Our results show that flood and fire are important to the conservation of this monodominant community.

Recent fire regime in the southern boreal forests of western Siberia is unprecedented in the last five millennia

Wildfires in Siberia are documented to have increased in frequency and severity over recent decades. However, in the absence of long-term records, it is unclear how far and why this trend deviates from centennial to millennial scale variability. Here we reconstruct past patterns of fire frequency and fire type, and explore how the fire-related traits of boreal species and plant functional types (PFTs) determine ecosystem responses to changing fire regimes. We use charcoal-based reconstructions of the fire regime in combination with a pollen-based assessment of vegetation composition in two boreal forest peat profiles from Plotnikovo Mire in western Siberia that span the last 2400 and 5000 years. We found moderate levels of biomass burning between 5000 and 4000 cal yr BP. Biomass burning and fire severity i.e., more biomass burning per fire episode, increased over the last 1500 cal yr BP associated with the dominance of fire invaders (Betula). Conversely, between 4000 and 1500 cal yr BP lower biomass burning, with perhaps fire types affecting mostly litter and understorey vegetation, coincided with the dominance of fire resisters (e.g., Pinus sylvestris, P. sibirica, Larix) intermixed with a considerable number of fire avoiders (e.g., Abies sibirica and Picea obovata). This long-term perspective shows that the current fire regime commenced 1500 years ago and deviates from the trends observed over the last 5000 years. This deviation is linked to a combination of climate conditions conducive to fire, the amount and composition of woody fuels, and land use changes. Although pines reacted more sensitively to increased fire severity, the fire avoider Picea obovata appears to be much more vulnerable to both frequent, severe fires than Abies sibirica. We anticipate that climatically driven changes in fire weather, with frequent warm and dry spells, and anthropogenic land use intensification will heighten fire severity and their impact, driving vegetation composition towards Betula species to the detriment of Picea obovata. This study also shows that charcoal morphotypes can provide useful information on fuel and fire type, and that, although all macro-charcoal size classes reliably indicate local-scale fires, the larger fraction (>300–500 μm) allows the identification of on-site fire episodes. We recommend multi-site palaeo-fire reconstructions in boreal peatlands to adequately reflect the influence of localised peat moisture content, and vegetation composition and structure variability on the small-scale heterogeneity of fire type and spread. This will ensure that trends in fire regime dynamics are representative and not limited to the local scale. We also propose future directions in fire research that can be tested using fossil records of fire, climate and vegetation ideally in an interdisciplinary approach.

A deep learning approach to identify smoke plumes in satellite imagery in near-real time for health risk communication.

Background:Wildland fire (wildfire; bushfire) pollution contributes to poor air quality, a risk factor for premature death. The frequency and intensity of wildfires are expected to increase; improved tools for estimating exposure to fire smoke are vital. New generation satellite-based sensors produce high-resolution spectral images, providing real-time information of surface features during wildfire episodes. Because of the vast size of such data, new automated methods for processing information are required.Objective:We present a deep fully convolutional neural network (FCN) for predicting fire smoke in satellite imagery in near real time (NRT).Method:The FCN identifies fire smoke using output from operational smoke identification methods as training data, leveraging validated smoke products in a framework that can be operationalized in NRT. We demonstrate this for a fire episode in Australia; the algorithm is applicable to any geographic region.Results:The algorithm has high classification accuracy (99.5% of pixels correctly classified on average) and precision (average intersection over union = 57.6%).Significance:The FCN algorithm has high potential as an exposure assessment tool, capable of providing critical information to fire managers, health and environmental agencies and the general public to prevent the health risks associated with exposure to hazardous smoke from wildland fires in NRT.

Shaping Mediterranean landscapes: The cultural impact of anthropogenic fires in Tyrrhenian southern Tuscany during the Iron and Middle Ages (800–450 BC / AD 650–1300)

Charcoal analysis, applied in sediment facies analysis of the Pecora river palaeochannel (Tyrrhenian southern Tuscany, Italy), detected the occurrence of past fire events in two different fluvial landforms at 800–450 BC and again at AD 650–1300. Taking place in a central Mediterranean district adequately studied through palaeoenvironmental and archaeological research, the investigation determined land changes, time phases and socio-economic driving forces involved in dynamic processes of fire. The fire sequences had purely anthropogenic origins and were linked to forest opening and reduction by local communities. Introduced by the Etruscans, fires dated to 800–450 BC involved mainly the forest cover on the hilly slopes, ensuring agricultural exploitation. From AD 650, fires contributed to Medieval upstream reclamation and vegetation clearing of flat swamplands. From AD 850 to 1050, the use of fire spread over a wider area in the river valley, increasing arable lands. Between AD 1150 and 1300, fires belonged to a regional forest clearance phase. Medieval fire episodes had a paramount importance in shaping and determining the character of the Tuscan Mediterranean landscape. From AD 850, Medieval fire clearing influenced regional vegetation history contributing to the decline of the dominant deciduous Quercus woodland. Open habitats became the new form of a clearly detectable agricultural landscape from AD 950. The use of fire clearing and the resulting landscape changes in the Pecora river valley depended on the political strategies adopted by Medieval authorities and marked, in fact, the progression of a cultural landscape still characterizing central Tyrrhenian Italy.

Late-Holocene vegetation dynamics and disturbance regimes in north Patagonia Argentina (40°S)

Natural disturbance processes such as volcanic eruptions, fire and human activities are important vegetation drivers in north Patagonia. Here, we tested the impact of volcanic ash fall and fire on vegetation composition analysing two sediment records, Lake Avutarda and Lake Bruja, located in the forest-steppe transition at 40°S. In addition, our analysis provides the first account on the history of Nothofagus alpina at its eastern distribution limits. Our results comprise the last 3000 years, indicating the persistence of the vegetation despite evident volcanic activity documented by numerous tephra layers in both records. Eleven fire episodes were identified, while redundancy analysis indicates a non-significant influence of fire activity on the vegetation. The population increase of Nothofagus alpina represents the most important change in vegetation composition in the last three millennia. We speculate that the presumed change in climate, which led to the expansion of Austrocedrus chilensis south of the study area, also caused the increase of Nothofagus alpina populations in the region.