Possible role of allelopathy in growth inhibition of softwood seedlings in Newfoundland

Abstract

Failure of natural regeneration on harvested and burned areas and very poor growth of planted seedlings of softwood species, particularly black spruce (Picea mariana),¹ on many sites of central Newfoundland is a major silvicultural problem on the island. Some sites initially are sufficiently ‘stocked’ but one year later the site may experience 40% seedling mortality (W. J. Meades, pers. comm.). It is often the case that even if seedlings survive, their growth rate is extremely poor (cf. Botwood, Newfoundland). In the forests of central Newfoundland, a native ericaceous dwarf shrub called Kalmia angustifolia (hereafter mentioned as Kalmia) occurs most abundantly as an understorey species (Ryan, 1978). This ericaceous weed is particularly dominant in more open stands of black spruce (Vincent, 1965; Richardson and Peter Hall, 1973a, Richardson and Peter Hall, 1973b; Richardson, 1974a, Richardson, 1974b, Richardson, 1981), where it may constitute 80–95% cover under the forest canopy. Kalmia also dominates extensive areas of heathlands in Newfoundland (Meades, 1983a, Meades, 1983b). It is also an important understorey component in the forests of other Maritime Provinces of Canada and of the eastern United States (Hall et al., 1973 Meades, 1983). In Newfoundland, large areas of productive forest land are being invaded by this vigorously growing plant, particularly following fire and logging (Page, 1970; van Nostrand, 1971; Richardson, 1975).

Nomenclature for vascular plants follows Scoggan (1979).