Key message We propose a framework to derive the direct loss of aboveground carbon stocks after the 2020 wildfire in forests of the Chornobyl Exclusion Zone using optical and radar Sentinel satellite data. Carbon stocks were adequately predicted using stand-wise inventory data and local combustion factors where new field observations are impossible. Both the standalone Sentinel-1 backscatter delta (before and after fire) indicator and radar-based change model reliably predicted the associated carbon loss. Context The Chornobyl Exclusion Zone (CEZ) is a mosaic forest landscape undergoing dynamic natural disturbances. Local forests are mostly planted and have low ecosystem resilience against the negative impact of global climate and land use change. Carbon stock fluxes after wildfires in the area have not yet been quantified. However, the assessment of this and other ecosystem service flows is crucial in contaminated (both radioactively and by unexploded ordnance) landscapes of the CEZ. Aims The aim of this study was to estimate carbon stock losses resulting from the catastrophic 2020 fires in the CEZ using satellite data, as field visitations or aerial surveys are impossible due to the ongoing war. Methods The aboveground carbon stock was predicted in a wall-to-wall manner using random forest modelling based on Sentinel data (both optical and synthetic aperture radar or SAR). We modelled the carbon stock loss using the change in Sentinel-1 backscatter before and after the fire events and local combustion factors. Results Random forest models performed well (root-mean-square error (RMSE) of 22.6 MgC·ha−1 or 37% of the mean) to predict the pre-fire carbon stock. The modelled carbon loss was estimated to be 156.3 Gg C (9.8% of the carbon stock in burned forests or 1.5% at the CEZ level). The standalone SAR backscatter delta showed a higher RMSE than the modelled estimate but better systematic agreement (0.90 vs. 0.73). Scots pine (Pinus sylvestris L.)-dominated stands contributed the most to carbon stock loss, with 74% of forests burned in 2020. Conclusion The change in SAR backscatter before and after a fire event can be used as a rough proxy indicator of aboveground carbon stock loss for timely carbon map updating. The model using SAR backscatter change and backscatter values prior to wildfire is able to reliably estimate carbon emissions when on-ground monitoring is impossible.

The article presents data from the study of vegetation dynamics in the Chornobyl Exclusion Zone 30 years after the nuclear disaster and the resettlement of its local people. The 1993 prognostic data on the further development of grass and forest community groups in this area was only partially correct. The new prognosis for demutation successions reflects deviations from the linear development with a possible horizontal "shift", depending on climatic conditions, bio-ecological features of plants, as well as the impact of fires. Based on the analysis of recent data from geobotanical studies of the vegetation, the values of ecofactors that determine the course of demutation of communities were calculated. In particular, the classic course of succession is now inherent in the former settlements of the exclusion zone where the formation of forests takes place. In the old fallow lands, the previously prevailing Elytrigia repens has lost its dominant position, and has been replaced by Calamagrostis epigejos, which we associate with a certain deficiency of nitrogen compounds in the soil. The allelopathic properties of cereals inhibit the process of replacing grass communities with forest ones, which affects the course of succession. The issues of demutation of residential areas of the Exclusion Zone are considered and the sequence of changes in different habitats is described. Post-pyrogenic changes in the forest vegetation are noted and the capacity of invasive plant species to invade natural ecosystems are characterized. It is emphasized that frequent and large-scale fires cause a significant imbalance in forest ecosystems, and result in the appearance of a largenumber of alien species.

Розглянуто фактори змін біотичного різноманіття у зонах бойових дій, аналіз яких оснований на попередньому досвіді польових робіт авторів на сході України, а також на джерелах даних щодо поточної ситуації в інших регіонах країни, де відбувалися воєнні дії. Наведено приклади негативних змін, що проявляються на рівні життєдіяльності окремих особин, популяцій та угруповань. Це, як правило, загибель тварин від вибухів, хімічного забруднення, підриви на мінах, поведінкові зміни від стресу, руйнації біотопів тощо. Водночас зафіксовано й окремі позитивні зміни, пов'язані з припиненням фактично всіх традиційних форм природокористування, що сприяє зростанню популяцій деяких видів. Крім того, в таких зонах почастішали випадки реєстрації певних раніше відносно рідкісних і вразливих видів.

The present study is aimed at evaluating the genetic diversity, genetic status and the extent of hybridization with the domestic horse for the Przhevalski’s horse (Equus ferus przewalskii Poliakov 1881) population free-ranging in the territory of the Chernobyl Exclusion Zone (CEZ) in Belarus and Ukraine. The sample size included 12 individuals (10 sampled in the Belarusian part of the CEZ and 2 from the Ukrainian part of the CEZ). Ten microsatellites recommended by the International Society for Animal Genetics (ISAG) for horse genetic status and pedigree determination were used as markers in this study. The fragment analysis data obtained utilising this microsatellite panel determined that two individuals from Belarus possess no allelic variants typical for Przhevalski’s horse. Most of the other individuals presented diagnostically valuable allelic variants. Demographic history analysis for the population did not indicate any drastic population shrinkage events in the population’s recent history. The studied population is characterised by heterogeneous population structure with signs of inbreeding (0.21 %), intermediate level of genetic diversity (He = 0.63) and allelic richness (5.15), possesses 16 unique alleles among 2 microsatellite loci and valuable alleles for loci HMS3 and HMS7 (46.4 and 67.9 % specific alleles for Przhevalski’s horse, respectively). Genetic structure evaluation for the population was performed via Bayesian population structure analysis and factorial correspondence analysis (FCA), which indicated the presence of intrapopulation genetic subdivision. Taking into account the obtained indicators of genetic diversity, we may conclude on the relatively favourable status of Przewalski’s horse in the exclusion zone with good potential for the long-term existence of the species population in the wild. In order to minimise inbreeding effects and the risk of a decline in genetic diversity in the population of Przewalski’s horse of the exclusion zone, as well as to increase the value of this free-living group to preserve the gene pool of the species as a whole, it is necessary to provide detailed genetic monitoring of the livestock’s state, as well as develop a regional population management plan, including measures aimed to minimise the possibility of further hybridisation of wild horses with domestic ones.