Interactions between seed bank size, fuel accumulation rates and fire interval on contrasting substrate types in shublands of the mid-west region of Western Australia

There is remarkable variation in species presence and dominance observed in the kwongan vegetation, of the central west of Western Australia, at all scales (i.e. point, beta and gamma diversity) and it is recognised as a global biodiversity hotspot. Among adaptations observed in this flora is canopy seed storage (serotiny), which is very commonly exhibited in these shrublands (kwongan) over a range of soil types typified by low resource availability for growth and reproduction. This study comprises the life history patterns of serotinous species on two different geology types; 1. Non-calcareous sandplains, and 2. Coastal limestones. Serotinous species have been chosen as a representative of all woody perennial shrubs within the region. They were chosen because they display their entire reproductive history within the plant canopy, making population dynamics easier and more accurate to quantify. The study found that vegetative growth, measured as plant volume, did not greatly differ between the two soil substrates. Although, overall community biomass was observed to be significantly higher for sites of coastal limestone regions, presumably resulting in higher fire frequency. Seed accumulation was found to occur at a significantly higher rate for sites on the coastal limestone. This trait is thought have evolved due to higher fire frequency in these regions. The observed mechanism of faster seed production is the result of a feedback loop between resource availability, increased biomass production and higher fire frequency