Chronic Gamma Radiation Affects the Distribution of Radial Increment in Pinus rigida Stems.

Exposure of pitch pine trees to chronic ionizing radiation at rates between 1 and 5 roentgens per day for several years causes reduction of radial increment throughout the stem, the reduction being most ponounced near the base of the tree. Both the size of the tree crown and climate influence the severity of the effect, trees with large crowns showing little effect at low exposures except in years of environmental stress.