Просторово-часовий розподіл пожеж у природних ландшафтах Рівненської області

Integrated fire management during the epoch of climate and land use change need to be organized on landscape level on the basis of strong vertical and horizontal co-operation between forestry and emergency agencies and local communities and requires clear understanding of fire regime and factors that it determined both in temporal and spatial aspects. For this purpose, fire regimes of natural and cultural landscapes of Rivne Oblast, Ukraine, for the period of 2001–2018 were studied based on remote sensing data. For getting better understanding of long-term pathways of wildfire regimes of natural landscapes of Rivne Oblast of Ukraine, we used data about hotspots from MOD14/MYD14 for number of fires, data about contours and areas of fires from MCD64A1and Landsat 8 OLI with classification of all fires on different levels of intensity and landcover type and data from three local meteorological stations on the fire weather danger level. The study showed that in Rivne Oblast for the period 7 fire maximums occurred, in particularly in 2002, 2009, 2012, 2015 and 2018. Official statistical data presents essentially underestimated area of fires: 257 ha in 2002 (while this study shows 750 ha based on RS data or 143 ha in 2015 (563 ha based on RS data). On average during the period, 190 wildfires with a total area of 12.6 thousand hectares occurred annually in landscapes of Rivne Oblast. The highest amount of fires occurred in the north part of the region – Rokytnivskii (62 000 ha burned), Dubrovitskii (26 000 ha), Kostopilskii (19 400 ha), Zarichnenskii (14 900 ha), Volodymyretskii (10 300 ha) districts. The main driver of fires is drought periods: 54.3 % of days in fire season determined as highest emergency level fire weather class – V, 15.3 % days – IV class, 18.5 % – III class. High level of fire weather danger in the region and permanent presence of ignition sources of human origin determine seasonal patterns of burning. Seasonal fire peaks occur in March (80 000 ha burned)-April (87 300 ha burned or 29.6 % of the average number of wildfires), August (32.2 %) and September (19.9 %) – totally 127 000 ha burned, when the maximum level of preparedness of fire-fighting brigades should be provided. Long-term dynamic showed increase of the average annual fire area for the period from 7.4 to 17.8 thousand hectares. The increase of annual amount of days with high and emergency fire whether levels from 24 to 62 during last 13 years is detected. Shortcomings of the existing system of statistical data collection on wildfires as an important component of fire management are discussed.Аналіз історичної динаміки пожеж та встановлення їх просторово-часових особливостей є основою для розроблення плану управління пожежами та стратегічного розміщення протипожежних сил і засобів на місцевості, а також здійснення попереджувальних заходів. Використовуючи дані дистанційного зондування Землі, отримано основні показники горючості природних територій Рівненської області за період з 2001 по 2018 рр. та виконано їх аналіз. Щорічно на території області відбувається в середньому 190 випадків пожеж на загальній площі 12,6 тис. га. Усереднені дані свідчать про тенденцію до зростання показників горючості території, зокрема середньорічна площа пожеж за період з 2001 по 2018 рр. зросла від 7,4 до 17,8 тис. га. За результатами дослідження встановлено, що найбільше пожеж стається у березні-квітні (29,6 %), серпні (32,2 %) та вересні (19,9 %), що повинно бути основою для максимальної готовності протипожежних служб у ці періоди. Виконано аналіз погодно-кліматичних показників за багаторічний період та досліджено їх зв'язок з основними показникам горючості. Зроблено висновки щодо проблеми пожеж у природних ландшафтах Рівненської області. Наведено недоліки наявної системи моніторингу пожеж як важливої складової системи охорони природних територій від пожеж

Open fires in Greenland in summer 2017: transport, deposition and radiative effects of BC, OC and BrC emissions

Highly unusual open fires burned in western Greenland between 31 July and 21 August 2017, after a period of warm, dry and sunny weather. The fires burned on peatlands that became vulnerable to fires by permafrost thawing. We used several satellite data sets to estimate that the total area burned was about 2345&thinsp;ha. Based on assumptions of typical burn depths and emission factors for peat fires, we estimate that the fires consumed a fuel amount of about 117&thinsp;kt&thinsp;C and emitted about 23.5&thinsp;t of black carbon (BC) and 731&thinsp;t of organic carbon (OC), including 141&thinsp;t of brown carbon (BrC). We used a Lagrangian particle dispersion model to simulate the atmospheric transport and deposition of these species. We find that the smoke plumes were often pushed towards the Greenland ice sheet by westerly winds, and thus a large fraction of the emissions (30&thinsp;%) was deposited on snow- or ice-covered surfaces. The calculated deposition was small compared to the deposition from global sources, but not entirely negligible. Analysis of aerosol optical depth data from three sites in western Greenland in August 2017 showed strong influence of forest fire plumes from Canada, but little impact of the Greenland fires. Nevertheless, CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar data showed that our model captured the presence and structure of the plume from the Greenland fires. The albedo changes and instantaneous surface radiative forcing in Greenland due to the fire emissions were estimated with the SNICAR model and the uvspec model from the libRadtran radiative transfer software package. We estimate that the maximum albedo change due to the BC and BrC deposition was about 0.007, too small to be measured. The average instantaneous surface radiative forcing over Greenland at noon on 31 August was 0.03–0.04&thinsp;W&thinsp;m−2, with locally occurring maxima of 0.63–0.77&thinsp;W&thinsp;m−2 (depending on the studied scenario). The average value is up to an order of magnitude smaller than the radiative forcing from other sources. Overall, the fires burning in Greenland in the summer of 2017 had little impact on the Greenland ice sheet, causing a small extra radiative forcing. This was due to the – in a global context – still rather small size of the fires. However, the very large fraction of the emissions deposited on the Greenland ice sheet from these fires could contribute to accelerated melting of the Greenland ice sheet if these fires become several orders of magnitude larger under future climate.</p

War drives forest fire risks and highlights the need for more ecologically-sound forest management in post-war Ukraine

Since 24 February 2022, Ukraine has experienced full-scale military aggression initiated by the Russian Federation. The war has had a major negative impact on vegetation cover of war-affected regions. We explored interactions between pre-war forest management and the impacts of military activities in three of the most forested Ukrainian areas of interest (AOI), affected by the war. These were forests lying between Kharkiv and Luhansk cities (AOI 'East'), forests along the Dnipro River delta (AOI 'Kherson'), and those of the Chornobyl Exclusion Zone (AOI CEZ). We used Sentinel satellite imagery to create damaged forest cover masks for the year 2022. We mapped forests with elevated fire hazard, which was defined as a degree of exposure to the fire-supporting land use (mostly an agricultural land, a common source of ignitions in Ukraine). We evaluated the forest disturbance rate in 2022, as compared to pre-war rates. We documented significant increases in non-stand replacing disturbances (low severity fires and non-fire disturbances) for all three of the AOIs. Damaged forest cover varied among the AOIs (24,180 ± 4,715 ha, or 9.3% ± 1.8% in the 'East' AOI; 7,293 ± 1,925 ha, or 15.7% ± 4.1% in the 'Kherson' AOI; 7,116 ± 1,274 ha, or 5.0% ± 0.9% in the CEZ AOI). Among the forests damaged in 2022, the 'Kherson' AOI will likely have the highest proportion of an area with elevated fire hazard in the coming decades, as compared to other regions (89% vs. 70% in the 'East' and CEZ AOIs respectively). Future fire risks and extensive war-related disturbance of forest cover call for forest management to develop strategies explicitly addressing these factors

Impact of Disturbances on the Carbon Cycle of Forest Ecosystems in Ukrainian Polissya

Climate change continues to threaten forests and their ecosystem services while substantially altering natural disturbance regimes. Land cover changes and consequent management entail discrepancies in carbon sequestration provided by forest ecosystems and its accounting. Currently there is a lack of sufficient and harmonized data for Ukraine that can be used for the robust and spatially explicit assessment of forest provisioning and regulation of ecosystem services. In the frame of this research, we established an experimental polygon (area 45 km2) in Northern Ukraine aiming at estimating main forest carbon stocks and fluxes and determining the impact caused by natural disturbances and harvest for the study period of 2010–2015. Coupled field inventory and remote sensing data (RapidEye image for 2010 and SPOT 6 image for 2015) were used. Land cover classification and estimation of biomass and carbon pools were carried out using Random Forest and k-Nearest Neighbors (k-NN) method, respectively. Remote sensing data indicates a ca. 16% increase of carbon stock, while ground-based computations have shown only a ca. 1% increase. Net carbon fluxes for the study period are relatively even: 5.4 Gg C·year−1 and 5.6 Gg C C·year−1 for field and remote sensing data, respectively. Stand-replacing wildfires, as well as insect outbreaks and wind damage followed by salvage logging, and timber harvest have caused 21% of carbon emissions among all C sources within the experimental polygon during the study period. Hence, remote sensing data and non-parametric methods coupled with field data can serve as reliable tools for the precise estimation of forest carbon cycles on a regional spatial scale. However, featured land cover changes lead to unexpected biases in consistent assessment of forest biophysical parameters, while current management practices neglect natural forest dynamics and amplify negative impact of disturbances on ecosystem services

Evaluation of the expected doses of fire brigades at the Chornobyl Exclusion Zone in April 2015

Assessment is given of area and behavior of large wildfire in the Chornobyl Exclusion Zone (ChEZ) which has been burning during April 27 - 29, 2015. Levels of radionuclide contamination of combustible material show that expected effective dose of firefighters during one fire-line hour did not exceed 0.64 μSv in case of external exposure and 0.37 μSv in case of internal exposure. It is shown that the expected effective dose of internal exposure of firefighters during suppression of wildfires in ChEZ was below the dose from external exposure. At the moment exposures of 90Sr and 241Pu (along with 238-240Pu and 241Am) make the most significant contribution to the internal dose of firefighters during forest and grassland fires suppression in the ChEZ

Resuspension and atmospheric transport of radionuclides due to wildfires near the Chernobyl Nuclear Power Plant in 2015: An impact assessment

International audienceIn April and August 2015, two major fires in the Chernobyl Exclusion Zone (CEZ) caused concerns about the secondary radioactive contamination that might have spread over Europe. The present paper assessed, for the first time, the impact of these fires over Europe. About 10.9 TBq of 137 Cs, 1.5 TBq of 90 Sr, 7.8 GBq of 238 Pu, 6.3 GBq of 239 Pu, 9.4 GBq of 240 Pu and 29.7 GBq of 241 Am were released from both fire events corresponding to a serious event. The more labile elements escaped easier from the CEZ, whereas the larger refractory particles were removed more efficiently from the atmosphere mainly affecting the CEZ and its vicinity. During the spring 2015 fires, about 93% of the labile and 97% of the refractory particles ended in Eastern European countries. Similarly, during the summer 2015 fires, about 75% of the labile and 59% of the refractory radionuclides were exported from the CEZ with the majority depositing in Belarus and Russia. Effective doses were above 1 mSv y −1 in the CEZ, but much lower in the rest of Europe contributing an additional dose to the Eastern European population, which is far below a dose from a medical X-ray