Invasion of coastal heaths of Victoria by Leptospermum laevigatum (J. Gaertn.) F. Muell

Abstract

Ecological and biological characteristics of the seral species Leptospermum laevigatum and the climax community, heath, are described. L. laevigatum invades only disturbed heathlands on sand podzols. On undisturbed soil, seedling survival is low and seedlings which survive are stunted. Stunting is attributed to the failure of mycorrhizal infection on soil of very low nutrient status. The addition of phosphorus ensured normal growth of seedlings on these soils. Top dressing with calcareous sand proved a poor source of additional phosphorus. To produce the observed densities of L. laevigatum in extensive areas of invaded heathland three factors are necessary: disturbed topsoil; a temporary increase in the soil phosphorus level; and release of the accumulated reservoir of seed. Fire is suggested as the factor likely to produce these conditions.