¹³⁷Cs and ⁹⁰Sr root uptake of pine saplings in a managed forest

¹ STUK, Radiation and Nuclear Safety Authority, Research and Environmental Surveillance, P.O. Box 14, 00881 Helsinki, Finland
² Finnish Forest Research Institute, METLA, Parkano Forest Research Station, Kaironiementie 52, 39700 Parkano, Finland

Abstract

Effects of liming (4000 kg calcium-magnesium carbonate per hectare) and soil preparation (with a disc plow) on ¹³⁷C sand Sr uptake of pine saplings (Pinus sylvestris) were studied in a dry heath forest in western Finland. Four treatments were studied: liming, soil preparation, liming followed by soil preparation, and control. The trees were planted in 1987 ; one year after the soil management, on a site contaminated by Chernobyl derived ¹³⁷Cs. Sampling of various tree parts and soil was carried out in 1991. Soil preparation increased highly significantly dry mass of the whole tree and branches and needles of C and C+1 year classes, and significantly masses of roots, stem, and older branches and needles. In all these fractions the content of Sr increased significantly. The ¹³⁷Cs concentrations in all tree fractions were highest in samples from the control plots, but Sr differed from this pattern. Soil preparation decreased significantly the ¹³⁷Cs concentrations in roots and living needles. The changes in ¹³⁷Cs and Sr contents in trees may partially be traced back to increased nutrient mobility and root mass and changed root distribution in soil, and also to different relations of Cs-K and Sr-Ca in uptake and translocation processes of trees.