Suppression of growth of surrounding regeneration by veteran trees of karri(Eucalyptus diversicolor)

Summary Isolated veteran karri (Eucalyptus diversicolor) trees depressed growth of surrounding 50 year old regeneration of the same species near Pemberton and Manjimup in Western Australia. The depressive effect was apparent up to two crown radii around the bole of each veteran. There was no difference between the amount of depression north and south of the veteran, hence shading by the veterans was discounted as a causative factor, and root competition for moisture is considered to be the most likely factor responsible for the depression of growth. In a forest stand, each 5% increase in crown cover of the veterans was associated with a 10% reduction of stem volume of the regrowth and a 15% understocking in regrowth crop trees.