Flowering and fruiting of arid zone species of Acacia in central Australia

A number of factors potentially affect flowering and fruiting of Acacia species in arid central Australia. Three phenological data sets were examined to determine the influence of edaphic, climatic and inherent evolutionary factors. Data for three intensively-studied common species showed that soil moisture over various lag periods was the best predictor of flowering, while site differences and temperature were of secondary importance. Soil moisture, site differences and daylength (time of year) were better predictors of fruiting. According to long-term records of a wider selection of species, the persistence of temperate-zone spring flowering patterns was apparent in one section of Acacia; the same patterns were also more common in shorter-lived species. Species from other sections and longer-lived species were more opportunistic in their flowering. Fruiting commonly occurred in the second half of the year, peaking in October, regardless of opportunistic or seasonal flowering. Phenological patterns are mixed, in keeping with the unreliable rainfall and environmental diversity of the Australian arid zone.