Determining the factors affecting seed germination in Livistona australis (Arecaceae) for the recovery of fragmented populations

Understanding seed germination and seedling recruitment is important for managing long-lived plant species, particularly palms that are transplanted from the wild and where regeneration is suppressed by seed predators and exotic herbivores. Seed viability, the timing of germination, and the factors influencing germination were investigated for the cabbage tree palm, Livistona australis (R.Br.) Mart. Greenhouse studies were combined with in situ experiments conducted on the Australian mainland and on a nearby mammal-free island. Under greenhouse conditions, > 90% of seed germinated within 4 months. In the field, burial rather than surface sowing of seed increased germination success. Seed without mesocarp and in sunlight had increased germination when compared with fruits in shade on the island, whereas neither presence/absence of mesocarp or light levels had any effect on the mainland. Germination success was substantially lower on the mainland, primarily because of high seed predation from the native bush rat, Rattus fuscipes. When caged to exclude vertebrates, 44% of seed were damaged over time by pathogens and invertebrates, with losses greater in sunlight than in shade. Results from the present study indicate that freshly buried seed with the mesocarp removed would have the greatest potential success in promoting the restoration of L. australis at degraded sites.