Effects of Ionizing Radiation on Terrestrial Ecosystems

The mechanisms that appear to account for the effects of ionizing radiation on the growth of plants are reviewed. Preliminary results are reported from a systematic study of the effects of gamma radiation on a terrestrial ecosystem and its components. The ecosystem chosen for this experiment supports a stana of the Long Island pine-oak forest. A 9500 c Cs/sup 137/ source, designed so it can be shielded when desired. was centrally located. Rates of exposure vary from several thousand r/day within a few Meters to about 2 r/day at 130 meters. The source has been exposed 20 hr/day since Nov. 22, 1961 Prior to installation of the source, a detailed survey was made on the species composition of the vegetation and on the size and vigor of individual plants. The early effects of radiation exposure are described. (C.H.)