Factors Influencing the Establishment of Seedlings of the Mallee, Eucalyptus luehmanniana (Myrtaceae)

Abstract

Factors influencing the survival of seedlings of the wet mallee-eucalypt Eucalyptus luehmanniana F.Muell. were examined using seedlings germinated in the laboratory and planted into the field. The effects of time since fire (0, 13 and 26 years), predation and position relative to adult canopy on seedling survival and growth in the first year after establishment were tested experimentally. Drought, predation by invertebrates and burial in leaf litter were identified as factors causing seedling mortality. Seedlings were most susceptible to predation at unburnt sites. Seedlings planted at burnt sites were more susceptible to drought, although a small percentage were killed by invertebrate predators. Burial of seedlings in leaf litter was most common under eucalypt canopies. After 200 days, seedlings in burnt sites were significantly more advanced in height, leaf area and leaf number than those in unburnt sites. It is predicted that E. luehmanniana seedlings are unlikely to achieve fire tolerance before fire occurs (assuming a fire interval of 10–20 years) unless they establish immediately after fire. The results suggest that mass establishment cued by fire allows seedlings to avoid predation, however mortality due to drought was greater at burnt sites than mortality due to predation at unburnt sites.