EFFECTS OF LEDUM-GROENLANDICUM AMENDMENTS ON SOIL CHARACTERISTICS ANDBLACK SPRUCE SEEDLING GROWTH

The effects of leaves and litter of the boreal forest understory shrub , Ledum groenlandicum, on soil characteristics and black spruce (Picea mariana) seedling growth were investigated. Organic and mineral soils , not previously associated with L. groenlandicum, were amended with l eaves and litter of this species. The objectives of the present study were: (i) to determine the changes in soil characteristics after amend ing with L. groenlandicum, (ii) to determine the quantitative variatio n in the concentration of water-soluble phenolic allelochemicals in mi neral and organic soil layers modified by L. groenlandicum and (iii) t o study the growth response of black spruce in soils treated with diff erent L. groenlandicum amendments. The amended organic and mineral soi ls were analyzed for pH, organic matter, PO4, N, Ba, Cu, Zn, Fe, Mn, C a, Na, K, Mg, Al and total phenolics equivalence. Results indicate tha t organic soils amended with L. groenlandicum leaves and litter were s ignificantly different from unamended control soil for most of the che mical characteristics, while amended mineral soil was different from t hat of unmodified mineral soil for PO4, organic matter, K and total ph enolics equivalence. Water-soluble phenolics from L. groenlandicum and changes in nutrient availability are plausible causes of L. groenland icum interference with black spruce seedling growth.