Effect of mulching on uptake of copper and nickel from smelter-polluted-soil by planted tree seedlings

Abstract

Copyright © 2013 Eva Komanicka et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Our aim was to determine the long-term effect of a mulching treatment on copper (Cu) and nickel (Ni) uptake by tree seedlings (Pinus sylvestris L. and Betula pubescens Ehrh.) from smelter-polluted forest soil in southwestern Finland. A mulch cover spread onto polluted barren soil did not have a clear positive impact on the biomass production and it did not decrease metal uptake by planted tree seedlings during a ten-year study period. In contrast, the Cu uptake by the above-ground parts of birch was increased as a result of mulching, although there were weak indications of slightly re-duced availability of Cu and Ni to roots in the case of both species. As Cu and Ni concentrations of foliage and bark have been shown to be strongly affected by surface deposited metal containing aerosols, only the woody compartments were used as indicators of metal uptake from soil. The Cu:Ni ratios of woody compartments were lower than those pre-dicted by the Cu:Ni ratios of soil suggesting that the soil extraction method used gives an underestimation of available Ni in relation to Cu. The lower soil Niexch concentrations on the mulched plots compared to the controls were in agree-ment with the slightly lower root Ni concentrations in the mulch treatments