What's unusual (or "unnatural") is that it's not just the macro level that was annihilated, but even the subterranean fungal network. Fire won't do that (unless the soil is very thin). Drought won't.

What is happening is apparently the entire cycle of repopulation of a food source for the most fundamental of ecosystem anchors.

What surprising is that this should be the equivalent of planting a garden with fuly sterilized soil. As someone else noted, why aren't wind-borne spores and nematode corpses revitalizing the subterranean ecosystem?

They said specifically that it were a cesium-137 source. I think the commentator is fair in pointing out that this finding is ultimately quite odd.

"An area of oak-pine wood was selected East of Upton, and a tower was constructed that could raise and lower a canister from underground that contained radioactive source material, allowing for controlled dosage levels that emanated in a radius from the tower. The canister contained Cesium-137, which would emit ionizing gamma radiation without making the surrounding area radioactive itself."