Oral Presentation 9th Australian Stream Management Conference 2018

Seed germination traits of two common floodplain eucalypts: optimum germination temperatures and influence of leaf litter (#38)

Ben E Vincent 1 , Rhiannon Smith 1 , Megan K Good 2 , Peter J Clarke
  1. University of New England, Armidale, NSW, Australia
  2. Federation University, Ballarat, Victoria, Australia

Eucalyptus coolabah subsp. coolabah (coolibah) and E.largiflorens (black box) are two dominant floodplain tree species of Australia’s Murray–Darling Basin. Over the past 200 years, widespread clearing and altered flood regimes have greatly reduced the abundance of these species in floodplain landscapes. Germination events are rare and establishment requirements for these species are poorly understood. Little is known regarding the life history of these two species, and until recently, mass recruitment events of coolibah were considered to be an invasive response activated by flood events. It is now thought that these rare recruitment events are an evolutionary response, and therefore part of the species’ reproductive strategy. We investigated the recruitment of coolibah and black box by conducting a series of germination trials to 1) determine the optimum temperature for germination, and 2) investigate the effect of leaf litter on germination. We found that both species required alternating temperatures for maximum germination, with coolibah exhibiting a wider range of optimal germination temperatures than black box. Leaf litter was found to inhibit germination in both eucalypt species due to the direct effect it has on light availability and temperature conditioning. The long-term survival of floodplain eucalypts depends on a thorough understanding of their life history. The results from this study can inform environmental water management and conservation decisions.

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