Effect of overwood trees on growth of Eucalyptus sieberi.  W. D. Incoll.  June 1979.  12 pp. (unpubl.)

SUMMARY

The suppressive effect of overwood trees on regrowth was studied by establishing transacts from isolated overwood trees into established 20-30 year old regrowth. Plots three metres in diameter were established at five metre intervals along the transects, and the three largest diameter regrowth trees in each plot were measured for diameter breast height over bark (DBHOB) and height. Basal area was estimated at each plot using probability proportional to size (PPS) sampling. The measurements showed that overwood trees influenced standing volume of regrowth in an area of four to six times the diameter of the overwood crowns.

The relationship of standing regrowth volume to distance from single overwood trees was calculated. Using this relationship stands were synthesised to estimate the effect on broad area volume stocking assuming a range of overwood retention. Several hypotheses of the effects of growth in overlapping zones of influence were tested in the course of the synthesis and further field data were collected to select the most appropriate hypothesis. An estimate of the loss in standing volume per hectare in the regrowth due to suppression by the overwood is as follows:

Also published:

Incoll, W.D.. (1979)  Effect of overwood trees on growth of young stands of Eucalyptus sieberi.  Aust. For. 42 (2): 110-26.