Context Conservation of threatened flora is best underpinned by structured monitoring and experimental programs that provide an understanding of population trends, demographic responses to threats, and the effectiveness of threat mitigation. Obtaining this information can be challenging for species with extremely small population sizes or extents where operational adaptive management may be deemed too high-risk and experimental manipulations logistically challenging to robustly implement. Aims To understand population trends in the critically endangered Ptilotus pyramidatus in the context of weed threats and weed management, in what at the time was the only known population. Methods Fixed quadrat ramet counts were conducted over 6 years across three treatments: (1) a largely weed-free Reference; (2) a Weedy treatment with high cover of Sparaxis bulbifera; and (3) a Weeded treatment with manual S. bulbifera removal after the first year of monitoring. In a glasshouse, the impact of exposure of P. pyramidatus to the herbicide metsulfuron methyl was tested. Key results Abundance of P. pyramidatus ramets remained similar over time and was significantly greater in Weeded plots, noting that random plot effects explained most variation. Glasshouse P. pyramidatus was susceptible to metsulfuron methyl. Conclusions Over the monitoring period, no consistent directional change in P. pyramidatus ramet abundance was detected. Application of metsulfuron methyl for S. bulbifera control will need robust testing on potentially sacrificial P. pyramidatus individuals in a field context before it could be considered for use in P. pyramidatus habitat. Implications Understanding impacts of threats and effectiveness of threat mitigation can assist in prioritising management resources.
Gosper et al. (Mon,) studied this question.