On April 26, 1986, explosions and a fire at a nuclear facility near Chernobyl in the then Ukrainian Soviet Socialist Republic released large amounts of radiation into the atmosphere that drifted far into western USSR and other parts of Europe.
At the time of the disaster a pine forest just a ways downwind from the disaster turned red and died. Some animals in the nearby areas also died or stopped bearing young. Horses left on an island in a river about 4 miles from the disaster site died when their thyroid glands were destroyed by radiation. Some forms of life thrive in the radiation. A robot found black fungi on the walls of the destroyed reactor. Thirty-one people died from the accident itself but there were many long-term effects such as cancers and deformities. After the accident an exclusion zone was set up and people evacuated from the area:
An area originally extending 30 kilometres (19 mi) in all directions from the plant is officially called the "zone of alienation". It is largely uninhabited, except for about 300 residents who have refused to leave. The area has largely reverted to forest, and has been overrun by wildlife because of a lack of competition with humans for space and resources.... Ukrainian officials estimate the area will not be safe for human life again for another 20,000 years.In 2011 the Ukraine opened up the zone to tourists.
Several scientific studies have shown that the radiation has had a negative effect on insects, birds, and mammals in the area but some experts disagree with the conclusions of the studies. A paper by Anders Moller of the University Pierre and Marie Curie in France and Tim Mousseau from the University of South Carolina said:
"Recent conclusions from the UN Chernobyl Forum and reports in the popular media concerning the effects of radiation from Chernobyl has left the impression that the exclusion zone is a thriving ecosystem, filled with an increasing number of rare species. Species richness, abundance and population density of breeding birds decreased with increasing levels of radiation."
Dr. Sergi Gashchak of the Chernobyl Center of the Ukraine told the BBC:
"Wildlife really thrives in Chernobyl area - due to the low level of [human] influence. All life appeared and developed under the influence of radiation, so mechanisms of resistance and recovery evolved to survive in those conditions.".Professor Mousseau called Dr. Gashchak's evidence purely anecdotal whereas the paper he wrote with Moller provides quantitative and rigorous data that shows that mammals have been negatively affected by radiation. Even so Mousseau thought it a good idea to set up the area as a wildlife sanctuary that would allow scientists to do long term studies on the effects of radiation on wildlife.
While Mousseau might be correct that overall species diversity may have declined in the Exclusion area evidence now shows that at least one species the brown bear has appeared in the area for the first time in 100 years. The Transfer, Exposure, Effects (TREE) project installed cameras that Dr. Gaschak found had a photograph of a brown bear (Ursus arctos). Mike Wood of the University of Salford told BBC that webcams clearly showed the bears. He said:
"There have been suggestions that they existed there previously but, as far as we know, no-one has got photographic evidence of one being present on the Ukrainian side of the exclusion zone."Part of the exclusion zone is in Belarus.
The TREE project website says that the TREE project wants “to reduce uncertainty in estimating the risk to humans and wildlife associated with exposure to radioactivity and to reduce unnecessary conservatism in risk calculations. Our studies will combine controlled laboratory experiments with fieldwork; most of which will take place in the Chernobyl Exclusion Zone.” As the appended video shows, there are rare wild horses in the Exclusion zone, introduced there to see if they would survive. They have and their offspring showed no ill effects of radiation. However, the zone has a burgeoning population of wolves who kill some of the horses. Also, poor Ukrainians hunt the horses for meat. At last count the number of horses showed a slight decline but there is no evidence that radiation was a factor.