Patterns of Flowering and Seed Production in Eucalyptus miniata and E. tetrodonta in a Tropical Savanna Woodland, Northern Australia

Abstract

The reproductive phenology-the annual and spatial variation in tree fecundity, ovule development and seedfall-of Eucalyptus miniata Cunn. ex Schauer and E. tetrodonta F. Muell. is described at a tropical savanna site in northern Australia from 1992 to 1994. There was substantial inter-annual variability in fecundity of both species at the individual and the population level. The proportion of ovules which survived did not vary significantly between years. Seed production and seedfall varied substantially between years with large seed yields in 1994 and low seed yields in 1993. Eucalyptus miniata and E. tetrodonta are separated in time (by 2-8 weeks) with respect to peak periods for all key phenology events-budding, flowering and seedfall. Both species are non-serotinous with all seed shed within 8 months of ovule initiation. Peak seedfall occurred up to 1 month before the first wet season rains for E. miniata and coincided with these rains for E. tetrodonta. Post-dispersal conditions for germination and establishment are more likely than seed supply to limit seedling establishment of E. miniata and E. tetrodonta.