Starting in 1961, Brookhaven National Labs regularly irradiated a section of forest with a canister of Cesium-137 to study the effects of hard gamma radiation on an ecosystem.

The Gamma Forest experiment was conceived around 1961 by Dr. George Woodwell with the express intent of studying long term effects of ionizing radiation on an ecosystem.

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.

The experiment was planned to take place over a number of years, but even in the very first year it was discovered that sensitivity to radiation damage was greater than anticipated, though still in a predictable range. The study proved the value of those predictive methods and ultimately opened up new avenues of research in radiobiology.

Woodwell would go on to become a prominent ecologist, being among the first scientists warning about the dangers of the pesticide DDT spreading through the food chain and damaging entire ecosystems; founding the Environmental Defense Fund; and pioneering research on climate change in ecosystems all across the globe. The Woodwell Climate Research Center (formerly Woods Hole Research Center) continues that work today.