Ecological aspects of soil seed-banks in relation to bauxite mining. I. Unmined jarrah forest

Abstract

Germinable seed stores were measured in jarrah forest soils at six sites during one year. The overall mean seed content to a depth of 5 cm was 292 seeds m -2 . There was a significant seasonal difference, with a maximum of 435 seeds m -2 in summer, after the majority of species in this Mediterranean ecosystem had flowered and set seed, and a minimum of 207 seeds m -2 in winter. There were also large site differences in both the densities of seed present and the species represented in the soil seed store. More than 85 species were represented in the germinable seed store from a total sampling area of 17.28 m 2 . The germination of Acacia drummondii, Acacia pulchella, Bossiaea aquifolium, Kennedia coccinea, Lasiopetalum floribundum and Trymalium ledifolium were significantly increased by heating the soil. Smoke produced a significant positive germination response in one species (Trymalium ledifolium). To maximize the contribution of the soil seed store to mine rehabilitation, the ideal revegetation sequence is to collect the topsoil immediately after clearing the vegetation in summer, immediately return the soil to an area to be revegetated, and carry out all earthmoving, landscaping and seedbed preparations prior to the onset of the autumn rains.