The accident at the Chornobyl Nuclear Power Plant in 1986 was one of the worst nuclear disasters that ever happened. When speaking about the long-term consequences, people naturally tend to refer to the negative impact on human health and on the environment, caused by the heavy radioactive contamination. However, there is at least one additional long-run side effect of this tragic occurrence that is often overlooked: the accident paved the way for an unparalleled case of large-scale rewilding of a settled region. On about 470,000 hectares of land that had formerly been densely populated and used for intensive agriculture, human activities ceased almost completely from one moment to the next. The people who once called this region home had to move away, the farmland was abandoned, and drainage canals were locked to prevent the spreading of wildfires and contaminated water. But the retreat of the population did not mean that all life had left the area. Nature took its chance and began to reclaim the territory, at its own will and pace.

This rewilding process has been observed by researchers for more than two decades. The findings are impressive: From 1999 to 2017, the wetland area increased by 680% and forest area by 14%. Now, more than 30 years after the accident, the territory looks like Polesian wetland habitats in northern Ukraine or southern Belarus, with typical seasonal floods and large mires.

The transformation of the animal communities was expected to be enormous after the massive decrease of human impact. Over a period of 22 years – from 1998 to 2019 – ornithologist Valery Dombrovski monitored population sizes, species composition, and habitat changes of birds of prey nesting in the Chornobyl Exclusion Zone. Parts of this study were supported by the Polesia – Wilderness without Borders project. The study area spans over 14,700 hectares of former farmland that had been intensively used until 1986.

During the study period 13 breeding species of daytime predators were recorded, and both species composition as well as the number of individuals changed significantly.

For instance, the globally endangered Greater Spotted Eagle (Clanga clanga), which relies on wetland habitats to hunt and is very sensitive to human disturbance, had been locally extinct in the area at the time of the nuclear catastrophe. 33 years later, in 2019, four pairs were recorded at the study site, and at least 13 pairs were known to be nesting in the whole Belarusian part of the Chornobyl Exclusion Zone. Today, this region is the only part of the world where the population of this rare species is growing. The increase of wetland areas alongside low levels of anthropogenic influence in the Chornobyl area created favorable living conditions for the Greater Spotted Eagle, which may help save this threatened species from extinction.

Another (locally) endangered raptor that reacts sensitively to human presence is the White-tailed Eagle (Haliaeetus albicilla). Before the nuclear accident, this bird could not be found in what is today the Chornobyl Exclusion Zone.  Only in 1992, White-tailed Eagles were first sighted here, and by 2010 their number had increased to 20 pairs. Unlike the Greater Spotted Eagles, White-tailed Eagles are non-migratory, so the availability of prey in winter is crucial for their survival. And here is how the true value of rewilding reveals itself: a functioning ecological community has returned to the area, composed of various species that sustain and support each other. Along with the birds of prey, top predators like wolves as well as their prey species (such as deer and moose) established viable populations, so that there is enough carrion for the White-tailed Eagle to make it through the cold season.

While the Greater Spotted Eagle and the White-tailed Eagle profited from the abandonment of the area, the scientists also observed decreasing populations of certain bird species. This applies to raptors that prefer hunting in farmland, such as Montagu’s Harrier (Circus pygargus), Lesser Spotted Eagle (Clanga pomarina), Honey Buzzard (Pernis apivorus), and Common Buzzard (Buteo buteo). Interestingly, at the beginning of the monitoring work in 1998, the population sizes of these species in the Chornobyl Exclusion Zone were much higher than the regional average.

Overall, the study shows that the passive rewilding of ecosystems is a complex and lengthy process. Some species needed nearly two decades to build stable populations, and others, like the Greater and Lesser Spotted Eagle, are still adapting. The Greater Spotted Eagle started colonizing the Chornobyl Exclusion Zone only 15 years after humans had left. Therefore, a long-term dynamic monitoring is the only way to assess the restoration process and the development of species composition and population sizes. But it has already become obvious that passive rewilding can bring European lowlands back to a near-natural state – both on the ecosystem as well as on the biodiversity levels.

36,000 hectares – this is the total area that gained legal protection through the creation of a new national park and a nature reserve as well as issuing protection passports for rare species’ habitat.

The year 2022 started with invigorating news: A decree issued by the President of Ukraine marked the official creation of the new Pushcha Radzivila National Park. The park protects a high conservation value area holding old-growth spruce forests, bogs and mires. Pushcha Radzivila, covering 24,265 ha , is home to more than 450 species of flora and 230 of fauna – dozens of which are nationally endangered. Among the national park’s inhabitants are Grey Cranes, Black Grouse, beavers, moose, lynx and various species of bats.

Bordering Rivnenskyi Strict Nature Reserve and Almany Mires Reserve, Pushcha Radzivila became an important link in the network of protected areas of Polesia. Through the designation of the new national park, the protection and ecological connectivity of the largest natural complex of bogs and transitional mires in Europe was enhanced.

Based upon field research conducted as part of the Wild Polesia project in 2020-2021, 142 habitat sites of rare species in Polesia were placed under legal protection. Their total area amounts to 6,372 ha. Forty two species now enjoy better protection, including mammals, birds, reptiles, insects, plants and fungi. Locating and mapping the space that species need to survive and securing this habitat through the “protection passports” plays a crucial role in bringing rare species protection into effect. This procedure envisages elaboration of scientifically grounded conservation measures for each single species (and sometimes even for certain habitat sites). These measures are mandatory, and their implementation is controlled.

Meanwhile, in February, 2022, the Almany Mires Nature Reserve got a new management plan for the coming 20 years. This was preceded by months of painstaking work that resulted in the list of scientifically grounded measures on conservation and support of valuable ecosystems, and of populations of endangered species of flora and fauna, as well as ensuring sustainable functioning of the nature reserve. It is expected that these measures will mitigate or eliminate the most significant threats to the ecosystems of the Almany Mires, such as climate change, drainage reclamation, wildfires, illegal wood felling, drying up of trees, road infrastructure development, spread of invasive species of flora and fauna.

The natural landscape of Polesia is shaped by the Pripyat – one of the few major European rivers that are still free-flowing. Advocates for Polesia’s wilderness focus on the need to maintain the natural state of the Pripyat as a key factor for the preservation of ecosystems and biodiversity in the whole region. This message was again reinforced by a study co-authored by Pavel Pinchuk from the project published in January 2022. Summing up the results of long-term monitoring carried out from 2001 to 2020, it proves that the natural hydrological regime of rivers is extremely important for Great Snipes during their breeding season.

Competing for a mate is extremely energy-demanding for lekking male Great Snipes. Therefore, rich feeding sites in close proximity to their breeding territories are essential for maintaining good physical conditions. Up to 90% of Great Snipes’ diet is made up of earthworms whose availability depends on the water level. Low water levels allows earthworms to disperse in a deep layer of soil. While, as the water table rises, they must congregate in a narrow layer of soil close to the surface. In this case, Great Snipes have easily available prey in abundance and their physical condition improves. At the same time, a further rise of water levels associated with flooding of the Great Snipes’ feeding territories leads to a decrease of the body condition of lekking birds. This is because the earthworms leave the flooded sites; their relatively short legs also don’t allow Great Snipes to wade in deep water. Thus, the birds have to expend much more energy, flying more often and further in search of prey.

The authors of the research highlight that the natural hydrological regime of the Pripyat with seasonal water level fluctuations is important for the preservation of lowland leks of the Great Snipe and, probably, of other species of waders breeding in the floodplains of Polesia’s rivers.

Another paper published in early 2022 looks into the unique case of wilderness restoration in the Chernobyl Exclusion Zone. The Chernobyl nuclear disaster (1986) was one of the worst man-made catastrophes in history. As a result of this tragic occurrence, in vast territories – previously densely populated and intensively used for agriculture – human activity ceased almost completely. The people who lived here up to 1986 had to relocate, the farmland was abandoned, and drainage canals were locked to prevent the spread of wildfires and contaminated water. As a result, a unique case of unguided nature restoration developed.

The long-term dynamic monitoring of landcover conducted in the Chernobyl Exclusion Zone from 1999 to 2017 shows an impressive increase in wetland and forest areas. In parallel to this, species’ composition and population numbers changed too. The monitoring of diurnal birds of prey carried out from 1998 to 2019 proved that the Greater Spotted Eagle and the White-tailed Eagle – both wetland specialists sensitive to human disturbance that had been locally extinct in the study area – returned, and their numbers increased. At the same time, the scientists observed decreasing populations of birds of prey that prefer hunting in farmland. Interestingly, at the beginning of the monitoring, the population sizes of these species in the Chernobyl Exclusion Zone were much higher than the regional average.

The study’s authors concluded that passive rewilding can bring European lowlands back to a near-natural state – at both an ecosystem and a biodiversity level.

Another achievement by our scientists in 2022 is the elaboration of the first bespoke landcover map of the whole of Polesia. This became possible due to the meticulous work on bringing the results of large-scale field surveys into correlation with the data provided by a pair of Sentinel satellites. Google Earth Engine is used for information processing. The map identifies a set of landcover classes that can be detected from the satellite’s orbit, like farmlands and urban territories, water, deciduous and coniferous forests, meadows, bogs and mires. The tool allows experts to carry out various environmental analyses. For instance, the map enables dynamic monitoring of restoration or degradation of natural areas, changes in land use, and analyzing the intensity of seasonal floods in Polesia. The tool can also be of use for assessing landscape connectivity, mapping species distribution, or protected areas enlargement.

We hope that the year 2023 will be more favorable for one of largest and most valuable natural landscapes of Europe and its people. And we enter the new year eager to keep on working for the benefit of Polesia’s wilderness and the communities that call this impressive landscape home.