Landscape Fire Research Articles

Particulate matter modelling techniques for epidemiological studies of open biomass fire smoke exposure: a review

Smoke exposure from landscape and coal mine fires can have severe impacts on human health. The ability of health studies to accurately identify potential associations between smoke exposure and health is dependent on the techniques utilised to quantify exposure concentrations for the population at risk. The evolution of spatial modelling techniques capable of better characterising this association has potential to provide more precise health effect estimates. We reviewed the literature to identify and assess the spatial modelling techniques available to estimate smoke PM2.5 or PM10 concentrations from open biomass or coal mine fires. Four electronic databases were searched: MEDLINE, EMBASE, Scopus and Web of Science. Studies were included if they utilised any method for modelling the spatial distribution of PM2.5 or PM10 concentrations from open biomass or coal mine fires and had applied the modelled PM to health data. Studies based on un-adjusted monitoring data, or which were not in English, were excluded. We identified 28 studies which utilised five spatial modelling techniques to assess exposure from open biomass fires: dispersion models, land use regression, satellite remote sensing, spatial interpolation and blended models. No studies of coal mine fires were identified. We found the most effective models combined multiple techniques to enhance the strengths and mitigate the weaknesses of the underlying individual techniques. “Blended” models have the potential to facilitate research in regions currently under represented in biomass or coal mine fire studies as well as enhancing the power of studies to identify associations with health outcomes.

Diagnosing spatial biases and uncertainties in global fire emissions inventories: Indonesia as regional case study

Models of atmospheric composition rely on fire emissions inventories to reconstruct and project impacts of biomass burning on air quality, public health, climate, ecosystem dynamics, and land-atmosphere exchanges. Many such global inventories use satellite measurements of active fires and/or burned area from the Moderate Resolution Imaging Spectroradiometer (MODIS). However, differences across inventories in the interpretation of satellite imagery, the emissions factors assumed for different components of smoke, and the adjustments made for small and obscured fires can result in large regional differences in fire emissions estimates across inventories. Using Google Earth Engine, we leverage 15 years (2003–2017) of MODIS observations and 6 years (2012–2017) of observations from the higher spatial resolution Visible Imaging Infrared Radiometer Suite (VIIRS) sensor to develop metrics to quantify five major sources of spatial bias or uncertainty in the inventories: (1) primary reliance on active fires versus burned area, (2) cloud/haze burden on the ability of satellites to “see” fires, (3) fragmentation of burned area, (4) roughness in topography, and (5) small fires, which are challenging to detect. Based on all these uncertainties, we devise comprehensive “relative fire confidence scores,” mapped globally at 0.25° × 0.25° spatial resolution over 2003–2017.We then focus on fire activity in Indonesia as a case study to analyze how the choice of a fire emissions inventory affects model estimates of smoke-induced health impacts across Equatorial Asia. We use the adjoint of the GEOS-Chem chemical transport model and apply emissions of particulate organic carbon and black carbon (OC + BC smoke) from five global inventories: Global Fire Emissions Database (GFEDv4s), Fire Inventory from NCAR (FINNv1.5), Global Fire Assimilation System (GFASv1.2), Quick Fire Emissions Dataset (QFEDv2.5r1), and Fire Energetics and Emissions Research (FEERv1.0-G1.2). We find that modeled monthly smoke PM2.5 in Singapore from 2003 to 2016 correlates with observed smoke PM2.5, with r ranging from 0.64–0.84 depending on the inventory. However, during the burning season (July to October) of high fire intensity years (e.g., 2006 and 2015), the magnitude of mean Jul-Oct modeled smoke PM2.5 can differ across inventories by >20 μg m−3 (>500%). Using the relative fire confidence metrics, we deduce that uncertainties in this region arise primarily from the small, fragmented fire landscape and very poor satellite observing conditions due to clouds and thick haze at this time of year. Indeed, we find that modeled smoke PM2.5 using GFASv1.2, which adjusts for fires obscured by clouds and thick haze and accounts for peatland emissions, is most consistent with observations in Singapore, as well as in Malaysia and Indonesia. Finally, we develop an online app called FIRECAM for end-users of global fire emissions inventories. The app diagnoses differences in emissions among the five inventories and gauges the relative uncertainty associated with satellite-observed fires on a regional basis.

Fuel dynamics and reburn severity following high-severity fire in a Sierra Nevada, USA, mixed-conifer forest

BackgroundHigh-severity fire in forested landscapes often produces a post-fire condition of high shrub cover and large loads of dead wood. Given the increasing patch size of high-severity fire and the tendency for these areas to reburn at high severity in subsequent wildfires, post-fire management often targets restoration of these areas. However, these areas are challenging to manage, in part due to limited knowledge of post-fire fuel dynamics over space and time and uncertainties in how specific fuel components such as snags and logs influence future fire severity. In this study, we used high-resolution aerial imagery collected nine years after a wildfire to measure snags, logs, and shrub cover within high-severity patches, and to assess how fuel development influenced reburn severity in a subsequent wildfire.ResultsThe abundance of snags, logs, and shrubs following high-severity fire varied with elevation and slope steepness; however, generalized additive models explained only 6 to 21% of their variation over the post-fire landscape. High densities of both snags and logs were associated with high reburn severity in a subsequent fire, while shrub cover had a marginally insignificant (P = 0.0515) effect on subsequent fire severity.ConclusionsOur results demonstrate that high levels of large dead wood, which is often not considered in fire behavior modeling, corresponded with repeated high-severity fire effects. Future research should leverage the increasing availability of high-resolution imagery to improve our understanding of fuel load patterns in space and time and how they may impact landscape resilience to facilitate management planning for post-fire forest landscapes.

Моніторинг ландшафтних пожеж Транскордонної Рамсарської території «Ольмани-Переброди» за даними дистанційного зондування Землі

Зміни клімату, землекористування та зростання відвідуваності лісів населенням зумовили суттєве загострення проблеми охорони лісів від пожеж, зокрема на заповідних та суміжних територіях. Транскордонна Рамсарська територія «Ольмани-Переброди», в яку входить Рівненський природний заповідник, характеризується високим рівнем ландшафтного та біологічного різноманіття за рахунок видів птахів, тварин і рослин, які знаходяться під загрозою зникнення, тому задача охорони таких територій від пожеж є однією з пріоритетних. Зважаючи на те, що в останні роки на території України почастішали випадки великих лісових пожеж, слід бути готовим до можливих випадків таких пожеж і на території Рівненського природного заповідника, до якого входить українська частина Транскордонної Рамсарської території. У статті наводиться аналіз динаміки пожеж, які відбулися в природних ландшафтах Транскордонної Рамсарської території «Ольмани-Переброди» упродовж 2006–2016 рр., на основі даних дистанційного зондування Землі. Отримані результати щодо часового та просторового розподілу пожеж на досліджуваній території за багаторічний період дозволять у майбутньому спрогнозувати ймовірність виникнення та поширення пожеж.

EFFECTS OF WILDFIRE EMISSION ON THE MORPHOFUNCTIONAL STATE OF THE CENTRAL NERVOUS SYSTEM IN WHITE RATS

Introduction. The study of the mechanisms of action of combustion products released during natural fires on the body and the development of appropriate preventive measures is an actual hygienic problem at the present stage. Material and methods. Experimental modeling of landscape fire was carried out for 7 days, 4 hours per day. Forest fuel, which is a living ground cover and plant residues, was used as a combustible substrate. The concentration of carbon monoxide, formaldehyde, furfural, and acetaldehyde was determined in the exposure chamber, the general qualitative composition of air and the target qualitative analysis for volatile aldehydes and ketones were carried out. After exposure rat behavior was observed through an open field test and Morris water maze, histological studies of brain tissue were done. Results. During the experiment changes in the structure of the behavior of white rats exposed to smoke were established to be characterized by a decrease in motor and exploratory activity, and an increase in the level of anxiety in females was also observed. When testing in the water maze of Morris revealed violations of spatial memory and the ability to navigational learning. Histological examination of the cerebral cortex in animals of the experimental groups revealed multiple foci of neuronophagy, expansion of perivascular spaces, and the development of glial cell replacement hyperplasia was noted. Conclusion. The results indicate the presence of a neurotoxic effect of combustion products, characterized by a decrease in the motor activity of animals, increased anxiety and impaired memory processes, as well as morphological changes in the brain tissue of white rats. However, in order to reveal the role of the impact of a complex of substances released during forest fires, their contribution to morphological and functional disorders, furthermore in-depth studies are required.

Use of the space segment of remote sensing for monitoring natural and anthropogenic emergencies in southern Russia

The article is devoted to the problem of remote sensing of the Earth. The article analyzes prospects for using the space segment of remote sensing for monitoring emergency situations of natural and man-made character in southern Russia (using the example of the Republic of Kalmykia) to predict and control emergency situations and eliminate their consequences. The use of a space monitoring system for identifying landscape fires in arid territories was suggested.

Fire caused demographic attrition of the Tasmanian palaeoendemic conifer Athrotaxis cupressoides

AbstractThe temperate island of Tasmania is a global centre of plant endemism, with relictual lineages that persist in topographically rugged, wet and cool refugia. An iconic example of these palaeoendemic plants is the slow‐growing conifer, Athrotaxis cupressoides D. Don (Cupressaceae). The geographic range of A. cupressoides has shrunk since European settlement because of destructive anthropogenic fires. Inscription of the Tasmanian Wilderness World Heritage Area in 1982 provided formal protection for Tasmania's palaeoendemic taxa, but they remain vulnerable to lightning‐ignited landscape fires, which are becoming more frequent due to climate change. We surveyed stands across the species’ range and found that stands damaged by fires in the 20th century had higher grass cover and were more exposed to hot northerly winds than unburnt stands. A recruitment bottleneck was evident, with juveniles absent in 28% of unburnt and 47% of burnt transects. Transects on small islands in lakes had lower herbivore densities and less evidence of fire than comparable mainland transects. However, the island transects had lower densities of A. cupressoides seedlings and saplings, despite similar densities of adult trees, suggesting factors other than fire and herbivory contribute to the poor regeneration. We also studied the effects of a lightning fire in 2016, finding it killed 68% of stems overall, with stems less than 30 cm diameter and those scarred by previous fires more likely to die. These findings of high adult mortality and poor regeneration following fire suggest that the geographic range of A. cupressoides will contract due to the increasing frequency of lightning‐ignited fires. Management responses to the increasing risk of landscape fires now include establishment of seed banks, restoration planting and use of irrigation to protect stands from active fires, in addition to rapid suppression of ignitions and targeted planned burning to reduce fuel loads in surrounding flammable vegetation.

Landscape Fires in Transbaikalia

This paper presents results of wildfire studies conducted Transbaikalia over the last five decades. Station-based experimental investigations into fire hazards of vegetation accomplished at the regional forest fire stations during those years covered all altitudinal vegetation zones, representative landscape localities and forest types. Route investigations were made in different natural areas. Arial monitoring of landscape fires was used during two fire seasons. Long-term effects of fires in the Baikal Natural Area and in Central Transbaikalia were investigated. Fire regimes in vegetation complexes were analyzed and for each of them the duration of the fire hazard was determined both as the total duration for the entire season and as a continuous duration for the period of the fire maximum. Characteristics of the regimes for the altitudinal belts are provided in three versions according to precipitation amounts for a season (normal, dry and wet). It is found that forest fires occur in intensive and extreme fire regimes where most of the vegetation complexes of the region become exceptionally hazardous as compared to adjacent areas. In such a situation, there are almost no barriers to fire, except for broad rivers, lakes and mountain crests. The forest fire frequency index is high due to a predominance of light coniferous stands. A rapid spread of fires is also promoted by dry grass stands and fire-hazardous shrubs where the fire is spreading nearly as fast as the speed of wind. It was established that unmown meadows, and abandoned pastures and croplands in the outskirts of villages present the threat of devastating fires not only in forests but also in settlements. In a situation, such as the one that arose in 2015, landscape fires turn to a natural disaster with severe forest-ecological consequences. Surviving forest stands decrease in productivity and increase in self-thinning, followed by an increasing degradation caused by subsequently recurring fires. Burns undergo local deforestation or a long-lasting replacement of coniferous stands by deciduous forests. The future runoff from the burned-over areas is able to enhance pollution of Lake Baikal. It is concluded that the EMERCOM resources used to fight the latest fires in Transbaikalia showed very little promise because of being delayed. A reasonable alternative to EMERCOM would involve advanced forecasting of high risks of fire occurrence in order to rapidly fight fires with moderate expenses without letting them turning to a natural disaster.

A systematic review and meta-analysis of the effect of landscape fire smoke particulate matter (PM) on asthma-related outcomes

TPS 681: Short-term health effects of air pollutants 1, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background: Asthma-related outcomes are among the most reported from human exposure to landscape fire smoke. Robust summary estimates are required to adequately inform health protection policy. Objective: To obtain summary estimates of the association between fine particulate matter (PM2.5) from landscape fire smoke and asthma-related outcomes. Methods: We conducted a systematic review and meta-analysis following PRISMA guidelines and registered the protocol in PROSPERO. Four databases (PubMed, Medline, EMBASE and Scopus) and reference lists of recent fire smoke and health reviews were searched. The Newcastle-Ottawa Scale was used to evaluate the quality of case-crossover and cohort studies, and a previously validated quality assessment framework was used for time series and ecological studies. Summary estimates were obtained for hospitalisations and emergency department (ED) visits. A descriptive analysis was done for physician visits and medication use. Publication bias was assessed using funnel plots and Begg’s Test. The trim and fill method was used when there was evidence of publication bias. Sensitivity and influence analyses were conducted on all endpoints to test robustness of estimates. Analyses were conducted in R version 3.5.1. Results: From an initial 181 articles (after duplicate removal), eighteen studies were included for the quantitative assessment. Fire smoke PM2.5 concentrations were positively associated with asthma hospitalisations (RR= 1.06, 95%CI: 1.03-1.09) and ED visits (RR=1.07, 95%CI: 1.03-1.09). Subgroup analyses found larger positive associations in adults aged over 65 years but not children for hospital admissions; and for all females, and adults aged over 65 years for ED visits. High heterogeneity between studies was observed, but results were robust to sensitivity analysis. Conclusions: Results for all ages and both genders are positive, but these seem to be driven by strong positive associations for all females and adults aged over 65 years. Risk estimates were higher than those reported for exposure to urban PM2.5.

Scaling and Complexity in Landscape Ecology

Landscapes and the ecological processes they support are inherently complex systems, in that they have large numbers of heterogeneous interacting components, interact in multiple ways, and exhibit scale dependence, non-linear dynamics, and emergent properties. The emergent properties of landscapes encompass a broad range of processes that influence biodiversity, ecosystem processes, and human environments. These properties, such as nutrient cycling, dispersal, evolutionary adaptation of organisms to their environments, and the focus of this article, ecological disturbance regimes (including wildfire), operate at scales that are relevant to human societies, but these are also often the scales at which ecosystem dynamics are most difficult to understand and predict. Modeling processes and interactions at the landscape scale, including future states of biological communities and their interactions with each other and with processes such as landscape fire, requires quantitative metrics and algorithms that minimize error propagation across scales. We identify three intrinsic limitations to progress in landscape ecology, and ecology in general: (1) the problem of coarse-graining, or how to aggregate fine-scale information to larger scales in a statistically unbiased manner; (2) the middle-number problem, which describes systems with elements that are too few and too varied to be amenable to global averaging, but too numerous and varied to be computationally tractable; and (3) non-stationarity, in modeled relationships or parameter choices that are valid in one environment but may not hold when projected onto future environments such as a warming climate. We illustrate these challenges with examples drawn from the context of landscape ecology and wildfire. Quantitative scaling relationships are the key to moving forward, and we review recent progress and paths to developing scaling laws in landscape ecology. We incorporate concepts of compression of state spaces from complexity theory to suggest ways to overcome the problems presented by coarse-graining, the middle-number domain, and non-stationarity.

Global fire emissions buffered by the production of pyrogenic carbon

Landscape fires burn 3–5 million km2 of the Earth’s surface annually. They emit 2.2 Pg of carbon per year to the atmosphere, but also convert a significant fraction of the burned vegetation biomass into pyrogenic carbon. Pyrogenic carbon can be stored in terrestrial and marine pools for centuries to millennia and therefore its production can be considered a mechanism for long-term carbon sequestration. Pyrogenic carbon stocks and dynamics are not considered in global carbon cycle models, which leads to systematic errors in carbon accounting. Here we present a comprehensive dataset of pyrogenic carbon production factors from field and experimental fires and merge this with the Global Fire Emissions Database to quantify the global pyrogenic carbon production flux. We found that 256 (uncertainty range: 196–340) Tg of biomass carbon was converted annually into pyrogenic carbon between 1997 and 2016. Our central estimate equates to 12% of the annual carbon emitted globally by landscape fires, which indicates that their emissions are buffered by pyrogenic carbon production. We further estimate that cumulative pyrogenic carbon production is 60 Pg since 1750, or 33–40% of the global biomass carbon lost through land use change in this period. Our results demonstrate that pyrogenic carbon production by landscape fires could be a significant, but overlooked, sink for atmospheric CO2.

The influence of planting size and configuration on landscape fire risk

Revegetating cleared land with native trees and shrubs is increasingly used as a means of addressing loss of biodiversity, degraded soil and water resources and sequestration of carbon. However, revegetation also brings a potential to alter fire risk due to changing fuel types across the landscape. Previous research has found that increasing the area of revegetation does not increase the risk of fire at a landscape scale, but it remains unclear whether the design of revegetation can be optimised to minimise risk. We evaluated if size and arrangement of revegetation affects fire size and intensity within an agricultural setting using a simulation modelling approach. Three revegetation planting designs were assessed, including small (3.2 ha) dispersed plantings, small (3.2 ha) plantings clustered into one third of the landscape, and large (29.2 ha) dispersed plantings, all resulting in the same overall percentage of revegetation (approximately 10% of the landscape). We simulated fires using Phoenix Rapidfire under varying planting design, weather, surrounding pasture conditions, and fire suppression. Planting design had little effect on fire sizes across the landscape, with larger plantings resulting in slightly larger fire sizes. Fires were smaller in landscapes with all planting designs compared with current landscape patterns. There was no significant influence of planting design on fire intensity. Weather and suppression had the strongest influence on both fire size and intensity, with larger and more intense fires under extreme weather conditions, with higher adjacent pasture loads and with no simulated suppression. Management of fuel loads in the pasture surrounding revegetation, weather and suppression are far greater risk factors for fire in these landscapes than planting design.

Hominin fire use in the Okote member at Koobi Fora, Kenya: New evidence for the old debate

Hominin fire use in the early Pleistocene has been debated since the early 1970s when consolidated reddened sediment patches were identified at FxJj20 East and Main, Koobi Fora, Kenya. Since then, researchers have argued for evidence of early Pleistocene fire use at a handful of archaeological sites with evidence of combustion. Some argue that morphological evidence of early Homo erectus fossils indicates a dietary shift to higher quality food sources, which could be achieved by cooking. Others contend that fire use does not become a regular behavior until later, in the middle Pleistocene, when archaeological sites begin to show regular evidence for fire use. An early date for hominin control of fire would help to explain the grade changes seen with the appearance of H. erectus, while a later date would mean that fire would have had little influence on the early development of the lineage. Early hominins would have encountered fire regularly on the landscape, increasing the possibility of hominins interacting with and habituating to natural landscape fire. Only a detailed understanding of the patterns of controlled and natural fires can lead to understanding of early hominin fire use. We present new work on the evidence of fire at the FxJj20 Site complex in Koobi Fora, dated to 1.5 Ma. We highlight evidence of burning found on site through Fourier Transform Infrared spectrometry, and describe ongoing work to investigate the association of hominin behavior and fire evidence. We present data supporting the hypothesis that the site is undisturbed and discuss spatial relationships showing burned material associated with non-burned material. We present data on a type of stone fragment, the Thermal Curve Fragment (TCF), which is indicative of knapped material being exposed to high heat. Finally, we suggest future directions on the topic of fire in the early Pleistocene.

Source or Sink? A comparison of Landfire- and FIA-based estimates of change in aboveground live tree carbon in California’s forests

Forests play a central role in addressing climate change, and accurate estimates of forest carbon are critical for the development of actions that reduce emissions from forests and that maximize sequestration by forests. Methodological challenges persist regarding how best to estimate forest carbon stocks and flux at regulatory-relevant scales. Using California, USA as a case study, we compare two approaches to stock-difference forest carbon estimation for aboveground live trees: one based on ground inventories and one on land cover classification of remotely-sensed data. Previous work using ground inventory data from the Forest Inventory and Analysis Program (FIA) showed net aboveground carbon (AGC) sequestration by live trees in California forests, while estimates using land cover classification from the Landscape Fire and Resource Management Planning Tools (Landfire) showed net reductions in live tree AGC over a similar time period. We examined the discrepancy by re-analyzing the FIA inventory data through the lens of a category-change analysis based on Landfire. This analysis showed more than 50% of the live tree AGC in fewer than 4% of Landfire-equivalent categories and that the overwhelming majority (>80%) of forest area did not change height category between measurement periods. Despite the lack of categorical change, the majority of FIA plots increased in both 95th percentile tree height and in live tree AGC. These findings suggest that an approach based on observing categorical changes risks undercounting AGC sequestration resulting from growth and thus overstating the relative importance of AGC reductions that result from disturbances. This would bias AGC flux estimates downward, leading us to validate the conclusion that live trees in California were a net sink of aboveground carbon in the decade ending in 2016. Our findings suggest an inventory-based or hybrid approach is preferable to methods that depend on categorical bins for estimating AGC in disturbance-prone forest ecosystems.

Peatland Hydrological Dynamics as A Driver of Landscape Connectivity and Fire Activity in the Boreal Plain of Canada

Drought is usually the precursor to large wildfires in northwestern boreal Canada, a region with both large wildfire potential and extensive peatland cover. Fire is a contagious process, and given weather conducive to burning, wildfires may be naturally limited by the connectivity of fuels and the connectivity of landscapes such as peatlands. Boreal peatlands fragment landscapes when wet and connect them when dry. The aim of this paper is to construct a framework by which the hydrological dynamics of boreal peatlands can be incorporated into standard wildfire likelihood models, in this case the Canadian Burn-P3 model. We computed hydrologically dynamic vegetation cover for peatlands (37% of the study area) on a real landscape in the Canadian boreal plain, corresponding to varying water table levels representing wet, moderate, and severely dry fuel moisture and hydrological conditions. Despite constant atmospheric drivers of fire spread (air temperature, humidity, and wind speed) between drought scenarios, fire activity increased 6-fold in moderate drought relative to a low drought baseline; severe (1 in 40 years) drought scenarios drove fires into previously fire-restrictive environments. Fire size increased 5-fold during moderate drought conditions and a further 20%–25% during severe drought. Future climate change is projected to lead to an increase in the incidence of severe drought in boreal forests, leading to increases in burned area due to increasing fire frequency and size where peatlands are most abundant. Future climate change in regions where peatlands have historically acted as important barriers to fire spread may amplify ongoing increases in fire activity already observed in Western North American forests.

Assessing Landscape Fire Hazard by Multitemporal Automatic Classification of Landsat Time Series Using the Google Earth Engine in West-Central Spain

Annual Land Use and Land Cover (LULC) maps are needed to identify the interaction between landscape changes and wildland fires. Objectives: In this work, we determined fire hazard changes in a representative Mediterranean landscape through the classification of annual LULC types and fire perimeters, using a dense Landsat Time Series (LTS) during the 1984–2017 period, and MODIS images. Methods: We implemented a semiautomatic process in the Google Earth Engine (GEE) platform to generate annual imagery free of clouds, cloud shadows, and gaps. We compared LandTrendr (LT) and FormaTrend (FT) algorithms that are widely used in LTS analysis to extract the pixel tendencies and, consequently, assess LULC changes and disturbances such as forest fires. These algorithms allowed us to generate the following change metrics: type, magnitude, direction, and duration of change, as well as the prechange spectral values. Results and conclusions: Our results showed that the FT algorithm was better than the LT algorithm at detecting low-severity changes caused by fires. Likewise, the use of the change metrics’ type, magnitude, and direction of change increased the accuracy of the LULC maps by 4% relative to the ones obtained using only spectral and topographic variables. The most significant hazardous LULC change processes observed were: deforestation and degradation (mainly by fires), encroachment (i.e., invasion by shrublands) due to agriculture abandonment and forest fires, and hazardous densification (from open forests and agroforestry areas). Although the total burned area has decreased significantly since 1985, the landscape fire hazard has increased since the second half of the twentieth century. Therefore, it is necessary to implement fire management plans focused on the sustainable use of shrublands and conifer forests; this is because the stability in these hazardous vegetation types is translated into increasing fuel loads, and thus an elevated landscape fire hazard.

The relationship between monthly air pollution and violent crime across the United States

ABSTRACTRecent evidence suggests a relationship between short-term pollution exposure and crime, with a particular emphasis on aggressive behavior. However, the previous analyses are limited in geographic scope. In this paper, we estimate the effect of fine particulate air pollution (PM) exposure on crime across 99% of counties in the contiguous United States. We combine monthly data on crime, PM, and satellite-derived smoke plumes for a ten-year period. We use adjusted satellite-based landscape fire smoke plume data as an instrument for overall changes in . Our findings are consistent with previous research and suggest that increases in raise violent crime rates, and specifically assaults. Our results indicate the effect is relatively homogeneous across the U.S. However, we find the effect is positively correlated with county median age, suggesting older populations are more susceptible to changes in air pollution. Our results indicate a need for more research on the physiological and social mechanisms behind the measured effects.

The practice of connectionist model for predicting forest fires in the Arctic zones of the Krasnoyarsk Territory

This paper presents data on the localization and number of forest fires that occur in the Arctic zones of the Krasnoyarsk Territory, as well as the possible causes of their occurrence. It is established that the main cause of forest and landscape fires are natural phenomena. A database of data normalized in a certain way about the factors shaping the occurrence of natural forest and landscape fires has been formed. The practice of connectionist algorithms, a forecasting model has been developed, and, based on data on forest and landscape fires in the Krasnoyarsk Territory; a model has been evaluated for using the model to predict fires in 2018. In order to compile a forecast of forest and landscape fires for 2019 in the Arctic zones of the Krasnoyarsk Territory using the connectionist algorithms, an optimal neuroarchitecture was chosen, which allows long-term time series forecasting.

Thermal curved-fragments: A method for identifying anthropogenic fire in the archaeological record

The archaeology of fire is a developing field. One challenge centers on equifinality: distinguishing the affects of wildfire versus anthropogenic fire. Especially where evidence for control of fire by humans in the early Pleistocene remains debated, there is little consensus regarding what constitutes clear evidence of human-control. Another concern is preservation bias, which reduces clearly identifiable archaeological signatures of fire. In this paper we argue that a peculiar lithic angular fragment—termed thermal curved-fragment (TCF)—exhibits statistically distinct, quantitative evidence of the confluence of human-knapped stone tools and exposure to a high-energy, long-duration, ground-level fire (i.e., campfires). Experimental TCFs are described and compared to unfired knapping debitage, natural exfoliations and suspected archaeological TCFs. The provenance of these archaeological specimens has previously been argued to infer hominin-controlled fire at 1.5–1.6 Ma at the Koobi Fora Formation. We also present data from experiments exposing stone flakes (arranged as “scatters”) of similar raw materials to those found in the Koobi Fora Formation to USDA prescribed burns in a variety of conditions approximating landscape fires. Results indicate that TCFs are formed specifically where (previously) knapped stone is exposed to high-energy ground level fires, similar to those seen in ethnographic campfires. Our analysis indicates that TCFs can be used in conjunction with other lines of evidence indicating the presence of anthropogenic fire in the archaeological record.

The effect of experimental fires on soil hydrology and nutrients in an African savanna

Savannas make up about 20% of the global land-surface and are dependent on fires to maintain a balanced ecosystem. Fires in other fire-driven landscapes, particularly wildfires, were found to have negative effects on various soil properties. However, there is a lack of studies confirming the effect of fires on soil hydrology in African savanna soils. A long-term fire experiment in a South African savanna provided an opportunity to investigate the effect of different prescribed fire frequencies on soil properties in situ across coarse-grained granitic and fine-textured basalt-derived soils. Soil properties were compared between soils exposed to annual fires, fires every 2–4 years and where fires have been excluded for approximately 60 years. Across all three fire treatments, unsaturated hydraulic conductivity (Kunsat) was measured using a Tension Disc Infiltrometer to infer infiltration rates, saturated hydraulic conductivity (Ksat) measured with a Guelph Permeameter, soil water potential calculated using a Decagon WP4-T Dewpoint Potentiometer to infer soil water retention and soil total C and N measured using a LECO CNS TruMac Series Analyser. Our study found that Kunsat is not affected by frequent annual fires which have infiltration rates similar to soils where fires have been excluded for nearly 6 decades. However, recently burnt granitic soils, i.e. three months prior, have significantly slower Kunsat which were as low as <1 mm hr−1 compared to a mean Kunsat of 30 mm hr−1 on annually burnt soils, alluding to short term fire impacts on soil infiltration. Hence, we believe that time following a fire plays a greater role on Kunsat than fire frequency. Fires did not affect Ksat within the initial 2–5 cm of the soil surface. In general, the granitic soils had faster Kunsat and Ksat than the basaltic soils. Soil water potential, total C and N was significantly greater in the fire exclusion sites over both parent materials. Soil water and nutrient availability is critical in a post-fire environment to facilitate vegetation recovery in African savannas. These systems are resilient to fires which do not have long-term negative impacts on soil hydrology and nutrients, but instead increases the spatio-temporal variation in soil properties necessary in maintaining savanna heterogeneity.