Observations and experiments on the Jignotuberous and seedling regeneration in spotted gum -ironbark forests are recorded. The effects of annual prescribed burning, severe wildfires, and regeneration burning on lignotubers and seedling establishment are described. Factors having a bearing on the long-term maintenance of the lignotuber-form are discussed. There is a striking response to complete removal of the canopy, but development of the lignotuberous seedlings is restricted for some distance from the edge of the surrounding canopy.The hypothesis is advanced that there may be in these forests a complex type of equilibrium in which the development of a given Jignotuberous or advance-growth stem is determined by the level of stocking in a wide arc of the surrounding stand, rather than by competitive pressure from the immediately adjacent or overtopping stems.

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A stem taper model, involving a high order polynomial developed using plantation hoop pine (Aroucaria cunninghamii Ait. ex D. Don) trees grown in Queensland, is presented. The stem profile for each tree was initially modelled using functions of diameter under bark and height, as the dependent and independent variables respectively. Parameter estimates from these individual tree regressions were subsequently modelled, using total height and diameter at breast height under bark (DBHub) as the independent variables. Finally, total height and DBHub were modelled in terms of predominant height' and diameter at breast height over bark (DBHob).The largest mean error in the estimates of stem diameter predicted using the final model, with predominant height and DBHob as the independent variables, was 0.12 em. The overall mean relative error in the estimate of volume, based on coefficients modelled using predominant height and DBHob, was 0.20 per cent. Apart from its accuracy, the main advantages of the model include its simplicity and its ability to model the whole tree using a single function.