Banksia Verticillata - Ecology

Ecology

The New Holland Honeyeater (Phylidonyris novaehollandiae) is a major visitor and pollinator of Banksia verticillata. These birds can travel 15 m (50 ft) between inflorescences in a feeding session, and preferentially choose flower spikes with partly opened flowers. Other honeyeater species observed, the White-cheeked Honeyeater (Phylidonyris nigra) and Western Spinebill (Acanthorhynchus superciliosus), visit this species to a much lesser extent. The Brown Honeyeater (Lichmera indistincta) has also been recorded as a visitor. Small mammals are not major pollinators, although Bush Rats (Rattus fuscipes) and House Mice (Mus musculus) have been recorded. Honey Bees (Apis mellifera) visit flower spikes but are not effective pollinators.

Banksia verticillata is significantly threatened by at least three microorganisms. Several populations have reduced or vanished from dieback (Phytophthora cinnamomi), such as those at Two Peoples Bay Nature Reserve and Gull Rock National Park. The honey fungus Armillaria luteobubalina has killed plants in Torndirrup National Park, and aerial canker (Zythiostroma) has decimated populations at Waychinicup National Park east of Albany.

Banksia verticillata plants are generally killed by fire and regenerate from seed. A field study after a mild fire in Torndirrup National Park published in 1994 found that plants burnt by fire were ten times as likely to have seedlings come up under their crown as unburnt plants (with an average of 25.2 seedlings per burnt plant), and burnt spikes released double the number of seeds as unburnt spikes. Despite this, interfire recruitment (seedlings arising between fires) has also been recorded, and might be more common than in other Banksia species. Observations at several of the populations showed many plants produced their first seed anywhere from 13 to 17 years of age, leading to a recommendation of 20 years between fires to allow seed banks to accumulate. If fire occurs too frequently, plants are burned before reaching maturity or before they have produced sufficient seed to ensure regeneration of the population. This may cause a population decline or even local extinction. Too long a time between fires also causes population decline, as more plants die of natural attrition without releasing their seed, resulting in seed wastage.