Early Stages of Regeneration After Burning in Dry Sclerophyll Vegetation. II. Regeneration by Seed Germination

Abstract

Following experimental burns in three dry sclerophyll communities, all except the geophytic species regenerated from seedlings in the first year. The annual and perennial species in the shrub strata regenerated from surviving seeds in the soil and ash, and the eucalypts from seeds released from the trees after burning.

Although many seeds were destroyed during the fires, the germination of most species was higher in burnt than in unburnt plots. Fire appeared to stimulate germination through direct heat effects on the seeds, and by removing inhibitors present in the unburnt vegetation.

Seedling mortality was highest during the first year. Many seedlings died while in the cotyledon stage, the main observed causes of mortality being desiccation, fungal disease and predation by insects. Seedling survival was enhanced by burning, owing to the removal of the litter and other fire-induced changes which made conditions more favourable for seedling establishment and/or growth.

Two years after burning, the relative positions of dominance of the three major species in the tall shrub stratum had changed compared with the pre-burn status of each. Evidence suggests that such shifts in dominance depend on a number of interacting factors which selectively promote or inhibit the recovery of each species.