Population Dynamics and Fire Response of Two Rare Shrubs in Brisbane Eucalypt Forests

Williams, P., Collins, E., Nash, M., Wood, C., Cooper, M., Hardie, C., and Messer, K. (2022)


Understanding how eucalypt forest flora respond to fire allows the implementation of a planned burn program that best suits the ecosystem, including threatened species. We report on the dynamics and response to low-intensity planned burning of two rare shrubs that grow in Brisbane eucalypt forests on metamorphic hills (Regional Ecosystem 12.11.5). A population of the Vulnerable Notelaea lloydii at Changing Mountain on the western side of Brisbane has been stable for the last seven years. All plants burnt in low-intensity fires in 2021 survived and rapidly regrew to over half their pre-fire height within a year. However, no seedlings of N. lloydii have been seen. The species’ Vulnerable status is supported. The Critically Endangered Zieria gymnocarpa is restricted to the Belmont Hills area in eastern Brisbane. The numbers of Z. gymnocarpa in a 100 m2 monitoring transect have dropped significantly from 248 in 2015 to only 34 plants in April 2022. The population decline was initially recorded in the dry period between 2015 and March 2016. Zieria gymnocarpa regenerated vegetatively after an August 2016 fire via coppice shoots at the base of stems and root suckers. Plant numbers a year after fire were similar to pre-fire density. However, the population has subsequently continued to decline and no seedlings have been seen during any survey. Further assessment is needed to estimate the population density across the species’ entire range and to investigate ways to promote its numbers. Given its small distribution and documented decline, we support the Queensland Nature Conservation Act 1992 status of Critically Endangered and suggest Z. gymnocarpa also be listed as Critically Endangered under the Federal Environment Protection and Biodiversity Conservation Act 1999.