The Effect of Excess Soil Copper on the Growth of Black Spruce and Green Alder Seedlings

Abstract

Increasing additions of Cu to soil up to 150 ppm decreased the growth of black spruce (Picea mariana [Mill.] B.S.P.) seedlings as measured by dry-weight production in 13-14 wk of growth after germination. The addition of lime and/or fertilizer improved the growth of black spruce seedlings at all Cu levels. Generally, fertilizer improved growth more at low Cu levels, and lime improved growth more at high Cu levels. Increased soil Cu concentrations had a much more drastic effect on the growth of green alder (Alnus crispa [Ait.] Pursh) seedlings, and lime fertilizer additions had much less of an ameliorative effect. In fact, the addition of lime at low Cu levels was in itself detrimental to alder seedling growth. Nodule biomass per seedling was very closely related to seedling biomass. In the unlimed soil there was no nodule production at Cu applications above 100 ppm. Nodule activity, however, seemed to be less affected by Cu per se than by the effect of Cu on the whole plant. Green alder would not appear, therefore, to be a useful species to use in the reclamation of soils with high Cu concentrations.