Fine-root growth, mortality and heavy metal concentrations in limed and fertilized Pinus silvestris (L.) stands in the vicinity of a Cu-Ni smelter in SW Finland

This study was conducted to assess 1) the growth of fine roots into ingrowth cores and fine root mortality, 2) the effects of liming and correction fertilization on fine-root growth and mortality, and 3) the concentrations of heavy metals in fine roots in control, limed or fertilized Scots pine stands at different distances from a copper-nickel smelter. Fine-root biomass in the ingrowth cores in the control plots varied between 1 (at 0.5 km from the smelter) and 252 and 271 g/m² (at 4 and 8 km, respectively). In the most polluted stand at 0.5 km, 98% of the fine roots that had grown into the ingrowth cores had died before sampling. Corresponding values for the other stands (4 and 8 km) were only 13-18%. At 0.5 km, liming increased the growth and survival of fine roots. The concentrations of Cu and Ni were also smaller in fine roots from the limed plot than those from the control plot. In the correction fertilization treatment at 0.5 km the total ingrowth of fine roots was at the same level as in the control, but less fine roots had died. Thus, the correction fertilizer treatment increased the survival but not the growth of fine roots. At 4 or 8 km, there were no significant differences in the fine-root biomass or necromass or element concentrations between the treatments.