General process, dynamics and modelling of radiocaesium cycling in contaminated forest: A whole-ecosystem approach

Abstract

We used a chronosequence approach to compare the distribution of l37 Cs and potassium (K) in the different compartments of three Scots pine stands. The cycling dynamic of both element was assessed as a function of stand development with emphasis on 137 Cs immobilisation in wood. lî7 Cs and K redistribute rather similarly between tree components, by circulating through the same pathways. U7 Cs immobilization in wood is, however, more important than for K, especially in old stands. Although the old stand accumulated more " 7 Cs from the Chernobyl event than the young stand, a much less limited pool of ll7 Cs characterises its current annual cycling when compared to EC. Differences in the current ll7 Cs content between young and old stands most likely reflect divergences occurred during the early redistribution rates after the fallout connected with differences in " 7 Cs interception rate. The WIP approach (combining n7 Cs radial pattern and biomass increment) was then preferred to the TF coefficient concept to quantify the actual IJ7 Cs immobilization in wood of each stand due to root uptake. Independently of the stand age, higher WIP values were related with the higher bioavailability of the '3?Cs located in organic layers.