Recruitment dynamics of the long-lived obligate seeders Callitris intratropica (Cupressaceae) and Petraeomyrtus punicea (Myrtaceae)

The. re-prone sandstone Arnhem Plateau is recognised as an international centre of plant species diversity. Key regional long-lived obligate seeders include the coniferous tree Callitris intratropica R. T. Baker & H. G. Smith, and the endemic myrtaceous, serotinous shrub Petraeomyrtus punicea (Byrnes) Craven. The paper reports a 6 year study of seedling-recruitment dynamics in natural stands of both species. For C. intratropica, it was found that (1) contrary to other published observations, initial growth was slow, with juveniles taking similar to 10 years to attain 2-m height, (2) maturation substantially exceeds 10 years and (3) previously unreported, even juveniles may occasionally resprout following very low-intensity. res after 100% scorch. For P. punicea, (1) maturation in some individuals commences as early as 4 years but generally takes at least 1-2 years longer and (2) juveniles (as well as adults) are killed following 100% scorch. The results emphasise the need for management-imposed fire regimes dominated by patchy, low-intensity fires for conservation of regional long-lived obligate seeders.