Comparison of the Early Growth Characteristics of the Eucalyptus Subgenera Monocalyptus and Symphyomyrtus

Abstract

The early growth characteristics of six Tasmanian species from each of the Eucalyptus subgenera Monocalyptus and Symphyomyrtus were examined. The species chosen from each subgenus came from a range of habitats extending from low altitude dry sclerophyll sites to subalpine sites. Marked differences in the rate of germination, percentage of viable seeds, total dry weight, and the root to shoot ratio were observed after 3 and 7 months' growth, as well as different responses to the level of nutrient provided. These subgeneric differences were generally larger than the differences observed between species chosen from one subgenus but from different ecological sites. The most striking differences were possibly the higher root to shoot ratio found in the subgenus Symphyomyrtus and the generally faster establishment of species from this subgenus. The results show that the two subgenera possess different early growth patterns. This may suggest that the subgenera exploit their environment in slightly different ways and may, at least partly, explain the frequent occurrence of mixed stands of eucalypts in south-eastern Australia. where stands frequently contain one species from each subgenus.