Abstract
Invading Pittosporum undulaturn tends to be clumped around the butts of established trees. This is due to the
preferential deposition of seeds in these sites by the European blackbird (Turdus merula) which is believed to
be the main vector of dispersal. Native silvereyes (Zosterops lateralis) eat some seed but are not considered
important in dispersal. The high mortality of seedlings in exposedsites reinforces the patchy pattern
originally dictated by seed dispersal. Seeds may germinate after seed fall in spring but most seeds germinate
in autumn. No seeds germinate during summer because of the low rainfall and high temperatures, the
optimum germination temperature being 18-21°C . After 16 months' storage at moderate temperatures and
humidities, 80% of seed was still viable but viability was reduced to 30% at very low humidities. Seedlings of
P. undulatum have three growth stages. The juvenile and transitional stages last 6-12 months and have
alternate leaves. In the adult phase a terminal vegetative bud forms at the stem apex. Bud burst may occur
several times a year in seedlings and twice a year in fruiting adults. The seedling root habit varies with soil
type. The seedlings are able to coppice if the shoot is removed P. undulatum is an aggressive invader of
eucalypt forests despite the poor survival of the initial colonizers. The formation of a regeneration niche
ensures the survival of succeeding generations. Consequently, P. undulatum is a permanent threat to the
Victorian vegetation.
Subject
Plant Science,Ecology, Evolution, Behavior and Systematics
Cited by
29 articles.
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