Reconstructing recruitment and persistence of the threatened tree species Persoonia arborea following disturbance

This work provides a novel, multi-proxy approach employing dendroecological techniques, to reveal patterns of species recruitment and population dynamics for long-lived species. In doing so it informs our understanding of the impact of disturbance regimes on plant community dynamics. Using the threatened, fire sensitive understorey tree Persoonia arborea as a case study, this study combined bomb-pulse radiocarbon dating, tree-ring analysis, and field surveys to reconstruct recruitment and persistence in response to disturbance from wildfire and commercial forest harvesting. We demonstrate rings are broadly annual but irregular with occasional missing or false rings reflecting the wandering lobate growth in the species. Growth declines with age, providing further support for the use of non-linear growth models for long-lived species. Reconstructing age using tree rings is a cost-effective option within the confines of an 18% error rate. Radiocarbon dating was the most accurate (CV = 5%) but also most expensive. The age-size (diameter at breast height) allometry was less precise (CV =22%) but is useful for rapid assessment of tree age. Using the best age-size models to reconstruct age distribution for over 5500 field observations, we demonstrate that fruiting probability increases with age, reaching 50% at 15 years and 90% at 46 years. Flowering peaks from January to March and fruit production peaks from August to October. Persoonia arborea recruits in pulses after fire, is killed in high severity fire but can persist at lower density within the footprint of light to moderate fire severity resulting in multi-age cohorts. The species can regenerate in the absence of fire and can regenerate continuously after clearfelling with a wide range of tree ages observed within the footprint of older (1970-2000) logging coupes. In this way, we demonstrate the utility of fire sensitive species in reconstructing disturbance history extends beyond the most recent fire.