The phenology of Eucalyptus camaldulensis (Dehnh, 1832) and Eucalyptus coolabah (Blakely & Jacobs, 1934) in the northern Murray–Darling Basin and implications for recruitment on floodplains.

Context: Published evidence suggests recruitment of floodplain trees is declining in the northern Murray–Darling Basin (MDB) and that this is linked to river flow. Aims: We investigated the reproductive phenology of Eucalyptus camaldulensis and Eucalyptus coolabah to better understand tree reproductive cycles and the influence of rainfall and flow on seed production. Methods: We surveyed phenological events (bud, flower and fruit production) over 6 years, at nine sites along the Condamine–Balonne River and examined correlations between these events and meteorological parameters. Key results: For both species, event timing was consistent across sites and years and event relative abundance scores were different between years. Bud abundance was correlated with rainfall, flooding and warming temperatures and E. coolabah produced additional bud crops after floods. Conclusions: The timing of events did not differ significantly from published results for the southern MDB. Rainfall, river flows and flooding in spring resulted in more abundant bud crops in E. camaldulensis and E. coolabah , and subsequently more abundant fruit crops. Fruit dehiscence coincided with summer–autumn flooding, which provides seed for germination. Genetic and physiological factors may also influence the observed pattern. Implications: These results will inform water planning in Queensland, Commonwealth Environmental Water Holder watering actions and long-term watering plans in the northern MDB. Eucalyptus camaldulensis and Eucalyptus coolabah are floodplain trees found in the Murray–Darling Basin (MDB). This long-term study observed the timing and abundance of buds, flowers and fruits at sites in the northern MDB and looked for patterns that would indicate the influence of river flows. Bud abundance, canopy seed storage and seed fall were influenced by moisture availability in both species. Image credit: J. L. Kerr. This article belongs to the collection Environmental flows in northern Murray–Darling Basin: what we know about the science and management after a decade of practice. [ABSTRACT FROM AUTHOR]