The Role of Fire in Establishment of Seedlings of Serotinous Species From the Sydney Region

Abstract

Observations and experiments were performed to examine the relationship between fire and seedling establishment in the following serotinous/woody species: Banksia ericifolia L.f., Banksia serrata L.f., Petrophile pulchella (Schrad.) R. Br. and Isopogon anemonifolius (Salisb.) Knight. For all species a moderate-intensity fire had no effect on the viability of seeds stored in cones compared to seeds stored in unburnt cones. Germinated seeds of all species, placed in meshed and unmeshed enclosures within an unburnt area, were consumed extensively by an unknown predator within 2 months of placement. No such effect occurred in similar treatments within a recently burnt area. Heating of the soil surface and the nature of substrates (litter, ash, bare soil) had variable effects on seedling establishment. Establishment of B. ericifolia and B. serrata was unaffected by the treatments whereas in P. pulchella and I. anemonifolius substrates and heating had significant effects. In P. pulchella establishment was significantly reduced on litter compared with pure ash. In I. Anemonifolius establishment was significantly higher on treatments with litter or mixed ash, except on soils that had received the low heat treatment, where there was no significant substrate effect. It was concluded that fire could create a more favourable soil-surface environment for establishment in P. pulchella only. In the other species, fire would have no effect or, in I. Anemonifolius, establishment might be enhanced in unburnt conditions. This conclusion does not take into account the effects of cover (overstorey and understorey) on establishment. It was concluded that predation of newly germinated seedlings may be the most important restriction on seedling establishment in unburnt populations.