THE NATURE OF INTERFERENCE POTENTIAL OF KALMIA-ANGUSTIFOLIA

The nature of interference potential of Kalmia angustifolia L., a bore al forest understorey shrub, was investigated in laboratory experiment s. Organic and mineral soils, not previously associated with Kalmia, w ere amended with different quantities of its leaf litter and leaf litt er leachates. The objectives of the study were (i) to determine change s in soil chemistry after amending with Kalmia and (ii) to determine t he effect of amendment on growth of black spruce (Picea mariana (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. Chemi cal characteristics of both organic and mineral soils were significant ly changed. Water-soluble phenolics in one of the amended organic soil s were significantly higher than in unamended organic soil. However, a ll of the amended mineral soils had significantly higher total phenoli c contents than unamended control soils. A linear decrease in N conten t was observed in amended organic and mineral soils with increasing qu antities of Kalmia leaf litter. Amended mineral soils had higher conce ntrations of Fe, Mn, Al, and PO4- than the control. We relate higher a ccumulations of PO4-, Fe, Mn, and Al in amended mineral soils to highe r soil phenolic contents. Amendment of organic and mineral soils signi ficantly 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 seedl ing growth.