We all know the story by now. On April 26, 1986, reactor number 4 at the Chernobyl Nuclear Power Plant, on the border of Ukraine and Belarus, exploded after a botched safety test caused a power surge that couldn’t be controlled, belching massive amounts of radioactive debris high into the atmosphere.

The human impact of this catastrophe was huge: At least 237 people suffered acute radiation sickness, while the World Health Organization expects that 4,000 people will die due to radiation exposure. Not only that, but the 30-kilometer (18-mile) evacuation zone displaced 130,000 people who have never been allowed to return. Despite this being one of the worst environmental disasters the world has ever seen, there has been one surprising benefiter: the wildlife.

The immediate aftermath of the explosion within a few kilometers of the plant was brutal. Initially, everyone within 10 kilometers (6 miles) was evacuated, as the radioactive plume (containing physical bits of nuclear fuel) rained down and the reactor continued ejecting material for up to 10 days. Not much is known about the immediate effect this had on the wildlife, as attention was rightly focused on the people who lived nearby. However, an obvious impact was what is now called the Red Forest.

“The Red Forest itself is quite small at only between 4 and 6 square kilometers,” the University of Portsmouth’s Jim Smith, who is currently looking at the impact Chernobyl had on water invertebrates, tells IFLScience. Smith previously conducted the most in-depth study on mammal abundance within the exclusion zone.

“But it got very intense radiation doses within the days after the accident. Chernobyl is different from Fukushima in that there was hot particle fallout, so little micron-sized bits of nuclear fuel were deposited within the 10-kilometer zone of the plant, and the Red Forest got a big amount of that.”

In fact, so intense was this initial dosage of dust raining down on the forest that anecdotal reports say that pine needles were physically pitted and burned as the hot nuclear fuel landed on them. Needless to say, the trees rapidly died, turning a rusty red and giving the small patch of trees its name. Even today, this region is still the most radioactive part of the whole exclusion zone.

 

The pine trees were, it would seem, more susceptible to the intense fallout than the deciduous trees. This, Smith suspects, is due to the fact that the deciduous trees could simply drop their leaves when they were affected by the radiation, but the evergreens couldn’t. This meant that many of the deciduous trees managed to survive enormous doses of radiation that would have undoubtedly killed a human.

While there are reports that the leaf litter built up in the forests because the microorganisms and invertebrates in the soil were blasted by the radiation, this is unlikely to be true. “People have done studies on soil invertebrates in the Red Forest, but in general they didn’t find a difference in the activity,” says Smith. As always, though, there are some who claim otherwise.

This probably isn’t surprising when you consider what it actually takes to kill an invertebrate. During the Cold War, among all the swirling fear and expectation that America, Russia, or both would actually drop a nuclear bomb, scientists zapped many organisms to see what would happen if this did come about. And, well, insects are pretty tough. So the fallout from Chernobyl is unlikely to have had a significant impact on them.

What happened to the larger animals during these early years is a little less well understood. The Iron Curtain still stood strong at the time of the blast, and so only Soviet scientists were allowed access to the site. They conducted yearly aerial surveys from a helicopter to count the elk, roe deer, and wild boar, but only in some parts of the exclusion zone, meaning that they were pretty limited in what they can tell us. But they did seem to show that within two years there was already a steady increase in mammal numbers.

It would seem that – despite popular assumption – the radioactive fallout from Chernobyl has had a limited impact on the wildlife in the region, and some species may have even benefitted from it.

This was backed up by the study that Smith conducted, along with researchers from Belarus, Russia, Germany, and the UK. They performed hundreds of kilometers of snow track surveys, in which they would go out into the exclusion zone after a fresh snowfall and walk a particular route, counting the tracks of the different species they came across. This gave them an indication of the relative population density of the large mammals in the region.

 

They then reconstructed the radiation dose on each of those routes to see if they could link the animal density to the amount of radiation that particular route received. “And we couldn’t,” says Smith. This doesn’t mean that there were not subtle differences on individuals as a result of the radiation, but there were no significant differences on a population level.

The beauty of this study was that they used the same surveying methods as the Belarussians do in their other National Parks, meaning that they could accurately compare their results of large mammal density within the exclusion zone to those outside. And let’s just say the results weren’t exactly expected.

While the number of deer and wild boar was comparable between the parks and exclusion zone, “wolf density was around seven times higher in Chernobyl,” explains Smith. This is mostly likely due to the lack of hunting pressure as there are simply far fewer people within the exclusion zone than in the other reserves, where some hunting does still take place. Interestingly, they concluded that the density of mammals depends more on human activity than on radiation.

“I mean that is not to say that there aren’t subtle effects, and there probably are effects on individuals, but in terms of populations I would say that the wildlife has benefitted,” says Smith, before adding, “that is not, of course, saying that Chernobyl has been in anyway a good thing – it has been a terrible thing for the human population – but if you’re purely looking at the wildlife, then you could say that the wildlife has benefitted.”

In effect, the Chernobyl exclusion zone has become an unofficial nature reserve, which is doing as good a job – and for some species better – at protecting the wildlife within it than many official ones. The future of this most unexpected haven, however, is uncertain.

The radiation levels have dropped so much by now that the Ukrainian government is actually thinking about opening up some areas of it for agriculture, while a Chinese company is constructing a solar plant within the exclusion zone. What this will mean for the wildlife, which has largely been free of human influence for the last three decades or so, is yet to be seen.