Long-term flowering synchrony of box-ironbark eucalypts

Long-term (1940-1970) flowering synchrony of Eucalyptus leucoxylon ssp. pruinosa (F. Muell. ex Miq.) Boland, E. microcarpa ( Maiden) Maiden, E. polyanthemos ssp. vestita L. A. S. Johnson & K. D. Hill and E. tricarpa ( L. A. S. Johnson) L. A. S. Johnson & K. D. Hill was quantified at the tree level. The least synchronous grouping was E. polyanthemos and E. microcarpa ( 0.06), with flowering overlap occurring in only 5 of the 30 years. The species with the most synchronous flowering were E. leucoxylon and E. tricarpa ( 0.62): flowering overlapped in 24 of the 30 years. Synchrony in the 1996-1997 flowering season was found to be 'typical': overlap among all species pairs and groupings was within the range delineated by the long-term data ( e. g. the synchrony of 0.53 for E. leucoxylon and E. polyanthemos was similar to its mean long-term overlap of 0.51). Individual species flowered synchronously, both within ( 0.82-0.92) and across sites (0.81-0.93). Flowering did not occur in any of the monitored trees during 1997-1998. Long-term synchrony values assist in quantifying the likelihood of hybridisation between species, and provide a baseline which may assist in detecting recent or future changes.