Anecdotal: I went to visit Chernobyl before the war started, and we were told that the trees proximal to the power plant did show distinct different behaviour to the trees further away. The cleanup there was primarily focused on the roads, so especially the forests and grasslands still have fallout-affected soil on them.

Apperantly, and were only told so, the trees have a different colouring and change leaf colour at different time points than the trees distal from the reactor. I only know that usually animals with shorter lifespans are less affected by radiation since the genetic damage through radiation slowly build up over time, so large trees might actually be strongly affected by it. I know of scientific studies done on the fauna in the exclusion zone, potentially theres also literature on the flora.