RADIOCONTAMINATION PATTERNS OF VASCULAR PLANTS IN A FOREST ECOSYSTEM

This study is based on measurments of radiocesium and potassium-40 in leaves, stems and roots of 48 vascular plants in a natural beech fores t in the Carnic Alps (NE Italy). The data have been submitted to numer ical classification, and the main results are: (a) radiocontamination patterns and ecology of the species are well related, (b) three main g roups of species with different radiocontamination can be distinguishe d: plants in clearings, forest plants rooting in the organic soil laye r, forest plants rooting in the mineral layer; (c) radiocesium tends t o be retained in the roots, especially in plants in the clearings; (d) Pteridophytes, contrary to all other plants, are able to discriminate between cesium and potassium at leaf level; (e) for all other species , cesium and potassium, once taken up by the plant, exhibit a similar behaviour; (f) total contamination by radiocesium is related to the de pth of the root systems, and to the unequal distribution of radiocesiu m in the soil profile. Species-specific mechanisms of differential abs orption are not evident in the investigated forest; the radiocontamina tion of plants can be easily explained in ecological terms. Radioconta mination on a water basis (Bq/1) is suggested as being much more appro priate for solving certain radioecological problems.