Dormancy Classification and Potential Dormancy-breaking Cues for Shrub Species from Fire-prone South-eastern Australia

摘要

Ecological studies require a clear understanding of the processes of dormancy release and germination. In fire-prone environments, implying that seeds are dormant because of a lack of germination from a soil-stored seed bank can confound results of experiments aimed at identifying dormancy mechanisms of fresh seeds. In this study, dormancy classification is endorsed as a starting point for establishing mechanisms that control dormancy of species from fire-prone vegetation. Shrub species within the physical dormancy (PY), physiological dormancy (PD), morphological dormancy (MD) and morphophysiological dormancy (MPD) classes were found to occur in the south-eastern Australian region in proportions similar to that of other fire-prone regions. Seasonaltemperatures, not fire cues, are the main factors that break physiologically related dormancy mechanisms and can also control the timing of germination. Seasonal emergence patterns are more likely for species with a PD component than for those with PY. This can delay seedling emergence depending on the timing of the fire event, particularly in regions without a distinct rainfall season, and potentially hinder recruitment. Species with MPD and PD may therefore be more sensitive to seasonal shifts in thefire regime, and this could have implications for community species composition and threatened species management.