Is tree growth reduction related to direct foliar injuries or soil chemistry modifications?

• Published in: Chemosphere (Oxford) Vol. 76; no. 10; pp. 1366 - 1371
• Main Authors: Aznar, J.-C., Richer-Laflèche, M., Paucar-Muñoz, H., Bordeleau, M., Bégin, Y.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-09-2009; Elsevier
• Subjects: Air Pollutants - analysis; Air pollution; Animal, plant and microbial ecology; Applied ecology; atmospheric deposition; Atmospherics; Biological and medical sciences; Cations; Ecotoxicology, biological effects of pollution; elements; Environmental Monitoring; forest soils; forest trees; Fundamental and applied biological sciences. Psychology; General aspects; heavy metals; Isotope ratios; lead; Lead (metal); Lead - analysis; Lead Radioisotopes - analysis; leaves; metals; mineral soils; Murdochville; phytotoxicity; Plant Leaves - chemistry; Plant Leaves - growth & development; polluted soils; Reduction; Smelters; Soil (material); Soil - analysis; Soil chemistry; Soil Pollutants - analysis; Soil Pollutants - chemistry; soil pollution; soil profiles; Terrestrial environment, soil, air; Tree foliage; tree growth; Trees; Trees - chemistry; Trees - growth & development; Quebec; Soil chemistry; Air pollution; Tree foliage; Murdochville; Modification; Soils; Growth; Foliage; Tree; Plant leaf; Damage
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2009.06.023

In the context of intense emissions causing atmospheric pollution, tree growth reductions could be related to soil chemistry modifications or direct foliar injuries. To verify these hypotheses, mineral soils were sampled in an area (Murdochville, Canada) where previous studies had demonstrated that tree growth was impacted by smelter emissions and that forest floor lead concentrations could be used as a proxy for atmospheric pollutant depositions. Samples were analysed for Al, Pb (concentrations and isotope ratios), basic cations (Ca, K, P, and Mg) and Zr. Mass balance calculations were performed on soil profiles to assess vertical migration of elements. Pb concentrations in litter diminished gradually with distance from the smelter. The Pb isotope ratios in these organic soil layers were close to those measured in the Murdochville ores. These patterns were not encountered in mineral soil layers. Pb isotope ratios in these layers were close to those measured in uncontaminated geological materials, and Pb concentrations and basic cation depletions were not related to the proximity of the smelter. Growth reduction was closely associated with litter Pb concentrations, which were used as a proxy for atmospheric deposition, but was not correlated with any elemental concentration or cation depletion measured in mineral soil layers. Our overall results suggest that trees responded mainly to direct atmospheric emissions, which caused foliar damage, rather than to soil chemistry modifications.