The research question centers on how the war has affected conservation efforts within the Ukrainian Emerald Network, a transboundary network established under the Bern Convention. The context is the ongoing conflict between Russia and Ukraine, which has significantly impacted the environmental sustainability of occupied territories. The purpose is to assess the impact of the conflict on forest cover change within the Emerald Network sites in the Luhansk region using satellite data. The study's importance stems from the need to understand the interplay between conflict, environmental policies, and conservation outcomes, particularly in regions facing geopolitical instability. The Bern Convention and its associated Emerald Network aim to achieve ecological sustainability in Europe, preserving biodiversity and promoting sustainable human-nature interactions. Ukraine joined the Convention in 1996 and began establishing Emerald Network sites in 2000, aiming for full implementation by 2020. However, the Russian military offensive, beginning in 2014 and intensifying in 2022, disrupted this process, leading to the occupation of parts of the Emerald Network sites and impacting conservation efforts. The Luhansk region, with its diverse ecosystems including forests, steppe, and sand dunes, contains 15 Emerald Network sites protecting numerous endangered species. The conflict has brought about various ecological impacts: militarization, land abandonment, and industrial damage, increasing ecosystem vulnerabilities. The study addresses these challenges by employing a long-term analysis of land-cover changes to evaluate the effectiveness of conservation policies under conflict conditions.

The paper reviews the history and positive impacts of the Bern Convention and the Emerald Network in Europe, citing examples of successful conservation outcomes, such as reforestation trends and stabilization of IUCN Red-List species populations. It then addresses the consequences of the war in Ukraine on sustainable development and biodiversity, highlighting physical damage to protected areas, interrupted management, and emerging risks to land use and conservation. Existing research on the war's impact on Ukraine's environment, including land cover changes, water pollution, and damage to infrastructure, is cited. The study also notes previous research on conflict's impact on African natural reserves and the potential for global species extinction due to military conflict and climate change.

The study employs a remote sensing approach due to the impossibility of gathering ground-referenced data in active conflict zones. It analyzes forest cover changes in the Luhansk region's Emerald Network sites from 1996 to 2020 using Landsat and Sentinel-1/2 satellite images, processed via Google Earth Engine. The analysis focuses on territories under Ukrainian and Russian control after the establishment of the demarcation line in 2014. The researchers used a supervised classification approach, generating cloud-free monthly composites and training data for each year (1996, 2000, 2013, 2020). A random forest algorithm was used for classification, with the number of decision trees adjusted according to data properties and computational limitations. The accuracy of the resulting tree cover maps was assessed using the F1 score. To mitigate biases in area estimation related to pixel resolution and classification errors, the researchers applied a stratified random sampling approach with strata defined based on forest cover changes. The formula used for sample size estimation, stratification, and area estimation is detailed, incorporating precision, strata weights, and buffering techniques to reduce uncertainties. The study divides the time period into three segments: 1996-2000 (before the Emerald Network's establishment), 2000-2013 (Emerald Network establishment before conflict), and 2013-2020 (after the conflict onset). The analysis compares forest area changes across these periods in territories under Ukrainian versus Russian control.

The analysis reveals a significant shift from deforestation to reforestation in the Luhansk region's Emerald Network sites between 1996 and 2020 in territories under Ukrainian control. From 1996 to 2000, annual deforestation rates were -0.86±0.22 th. ha per year under Ukrainian control and -0.28±0.1 th. ha per year under future Russian-controlled areas. However, after the start of the Emerald Network's establishment (2000-2013), reforestation rates increased to +0.67±0.09 th. ha per year under Ukrainian control and +0.19±0.06 th. ha per year in the territories that would later be under Russian control. After 2013, Ukraine-controlled territories continued reforestation (+1.19±0.18 th. ha per year), while Russia-controlled areas experienced substantial deforestation (-1.23 ± 0.15 th. ha per year). The study highlights that the areas under Ukrainian control experienced a net gain of 17 ± 1.74 th. ha of forest cover from 2000-2020, while Russian-controlled areas lost approximately 25% of their forest cover since 2013. The analysis of the Siverskyi Donets River floodplain, divided by the demarcation line, further supports these findings, showing a stark contrast between the reforestation in Ukraine-controlled areas (18% gain) and the deforestation in Russia-controlled areas (31% loss). The researchers attribute this difference to the continued implementation of forest management and environmental protection policies in Ukrainian-controlled areas, compared to the lack of such activities and the disregard for existing Ukrainian legislation in Russian-controlled areas.

The findings demonstrate the significant impact of the war-induced separation of territories from effective environmental protection institutions and policies. While the Emerald Network's establishment and implementation of the Bern Convention's policies contributed to reforestation in the Luhansk region before the conflict, the occupation led to a reversal of this trend in Russia-controlled areas. This underscores the critical importance of effective governance and policy implementation for achieving conservation goals. The disparity in forest cover changes between Ukrainian and Russian controlled areas showcases the direct link between institutional capacity, policy enforcement, and environmental outcomes. The study also highlights the limitations of conducting research in active conflict zones, underlining the reliance on remotely sensed data as a means to understand ecological consequences despite security and access challenges. The significant deforestation in Russian-controlled areas of the Emerald Network points towards a broader pattern of environmental degradation resulting from warfare and occupation.

The study demonstrates that despite the war, the pre-existing conservation policies and institutions within Ukrainian-controlled areas of the Luhansk region's Emerald Network maintained positive reforestation trends. However, the stark contrast with the deforestation experienced in Russian-controlled areas strongly supports the need for robust international cooperation to ensure the protection of biodiversity and environmental sustainability even amidst armed conflict. Future research could explore the long-term ecological consequences of the war in more detail, as well as examine the effectiveness of post-conflict restoration efforts.

The study is limited by the reliance on remote sensing data due to the lack of access to conflict zones, potentially leading to some degree of uncertainty in land cover classification. Furthermore, the analysis focuses specifically on forest cover changes and might not fully capture the complex ecological impacts of the conflict, such as water pollution and biodiversity loss. The study period ends in 2020, and the long-term impacts of the conflict from 2021 onward remain to be fully assessed.