Stand characteristics, understorey associates and environmental correlates of Eucalyptus tetrodonta F. Muell. forests on Gunn Point, northern Australia

An ordination study of 20 Eucalyptus telrodonta forest stands growing on deep earths in monsoonal Australia revealed two major gradients in understorey vegetation type. The first axis reflected both floristic and structural understorey variation, where litter and shrub cover were inversely related to grass cover. This axis is thought to reflect a complex fire-vegetation type interaction, where vegetation is primarily determined by the saturation of the soil profile in the wet season, as measured by the colour of the iron rich soils. On the second axis of the ordination, floristic composition but not vegetation structure, and stand height were found to vary with the intercorrelated measures of soil gravel and moisture supply. E. telrodonta is able to regenerate in the absence of fire, but firing appears to stimulate regeneration. All stands contained some advance growth, which occurs in distinct clumps, probably reflecting these plants clonal origin. Sapling presence in the stands is variable and the recruitment of advance growth into this size class appears to be related to overwood competition. The size class distribution of trees was found to be similar amongst the stands. therefore stand structure appeared to be independent of understorey type. In comparison to general models of temperate eucalypt regeneration processes the tropical eucalypts have evolved different regeneration strategies, possibly in response to the severe annual drought.