North Queensland Naturalist

A mast flowering event in a eucalypt of tropical upland dry sclerophyll forest

 

Donald C. Franklin, Terry Barnes and Alan Winlaw

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Abstract

Synchronised flowering of individuals of long-lived plant species at intervals of greater than one year, and which is bimodal between “much” and “few”, is known as masting. Masting appears to be common among eucalypts but has not been formally described as such. We provide quantitative data on a mass-flowering event in the Inland White Mahogany (Eucalyptus mediocris) in upland dry sclerophyll forest in north Queensland, along with anecdotal evidence that mass-flowering events in this species occur as infrequently as once per decade. Based on a survey of 549 trees spread across 37 sites, we estimate that 97% of healthy, mature Inland White Mahogany flowered between late November 2013 and February 2014, and 75% of these flowered heavily. Within the study area, flowering was staggered over about 12 weeks, with local synchrony being greater than regional synchrony. Fourteen percent of trees had capsules from a previous flowering event, and these trees displayed lower flowering effort than those without capsules. We argue that the event is appropriately described as masting. The factors driving masting in eucalypts are unknown, but this event may have been synchronised by a short but sharp drought 12 months prior.