The nature of interference potential of Kalmiaangustifolia

Abstract

The nature of interference potential of Kalmiaangustifolia L., a boreal forest understorey shrub, was investigated in laboratory experiments. Organic and mineral soils, not previously associated with Kalmia, were amended with different quantities of its leaf litter and leaf litter leachates. The objectives of the study were (i) to determine changes in soil chemistry after amending with Kalmia and (ii) to determine the effect of amendment on growth of black spruce (Piceamariana (Mill.) BSP) seedlings. All soils were analyzed for pH, organic matter, PO4−, N, Ba, Cu, Zn, Fe, Mn, Ca, Na, K, Mg, Al, and total phenolics. Chemical characteristics of both organic and mineral soils were significantly changed. Water-soluble phenolics in one of the amended organic soils were significantly higher than in unamended organic soil. However, all of the amended mineral soils had significantly higher total phenolic contents than unamended control soils. A linear decrease in N content was observed in amended organic and mineral soils with increasing quantities of Kalmia leaf litter. Amended mineral soils had higher concentrations of Fe, Mn, Al, and PO4− than the control. We relate higher accumulations of PO4−, Fe, Mn, and Al in amended mineral soils to higher soil phenolic contents. Amendment of organic and mineral soils significantly reduced the root and shoot growth of black spruce. This study demonstrates that Kalmia has potential for nutrient interference and does not rule out allelopathic effects of Kalmia to black spruce seedling growth.