Habitat segregation of 'Banksia marginata' and 'B. spinulosa' at Gibraltar Range, NSW

Abstract

Post-fire regeneration studies have shown that plant species may segregate into different habitats early in the lifecycle. At Gibraltar Range in northern NSW, 'B. marginata' is largely confined to swamp margins, whereas 'B. spinulosa' occurs in surrounding woodland. Both species are highly serotinous, although 'B. marginata' is an obligate seeder and 'B. spinulosa' is a resprouter. This project takes advantage of the recent fires of 2002 to examine factors operating during juvenile lifecycle stages to explain the observed habitat segregation. In the glasshouse under optimal moisture conditions, a reciprocal germination and seedling establishment experiment demonstrated that soil type was not a key factor contributing to habitat segregation. However, in the field both species had similar germination in the swamp, but 'B. marginata' had reduced germination in the drier woodland. The reduced 'B. marginata' germination may be caused by low soil moisture, and may determine habitat segregation. Additional glasshouse experiments will examine the effects of different soil moisture conditions on seedling growth and survival. Also, a reciprocal seedling transplant experiment will be conducted in the field to examine habitat effects on growth and survival. These results will be used to examine further the pronounced habitat segregation of these Banksia species.