Regarding Chernobyl, it's true that radiation has damaged the ecosystem, to what extent no one is exactly sure. But what is sure, is the diversity and numbers of wildlife is far greater than when humans were there. Nature is thriving in the area, and animals are showing far lower incidents of cancers than what was predicted.
The above is based on several articles I've read, and a couple of documentaries. Nature does indeed find a way.
edit -
here is one of the docu's I saw several years ago.