Comparative analysis of metal translocation in red maple (Acer rubrum) and trembling aspen (Populus tremuloides) populations from stressed ecosystems contaminated with metals

Uptake of contaminants by plants and their mechanisms have been the subjects of several studies, but reports on the analysis of metal translocation in hardwood trees are limited. The main objective of this study is to compare metal accumulation and translocation in red maple (Acer rubrum) and trembling aspen (Poplar tremuloides) growing in Northern Ontario. Results show that P. tremuloides leaf tissues accumulate more nickel (Ni) and zinc (Zn) than roots. The concentrations of these elements in A. rubrum were low in leaf, branch, and roots tissues compared to the bioavailable levels of these metals in soil. The translocation factors (TFs) of metals from roots to leaves were low for copper (Cu) and high for iron (Fe), magnesium (Mg), Ni, and Zn in P. tremuloides. They varied from 0.52 to 3.26 for Fe, 3.39 to 5.47 for Mg, 2.6 to 16.4 for Ni, and 1.41 to 4.1 for Zn. For A. rubrum the TF was low for all the elements except Mg. For this species, the TF values from roots to leaves varied from 0.08 to 0.17 for Fe, 2.62 to 4.13 for Mg, 0.26 to 0.81 for Ni, and 0.71 to 0.90 for Zn. Overall, Cu does not accumulate in P. tremuloides and A. rubrum tissues, and the two species have different mechanisms in dealing with the other main contaminants in the region, specifically Ni and Zn. P. tremuloides is an accumulator for Ni and Zn while A. rubrum is an excluder for Zn and it uses the avoidance strategy to deal with soil Ni contamination.