Lignotubers and meristem dependence in mallee (Eucalyptus spp.) coppicing after fire

Abstract

Field surveys of lignotuber meristem populations were undertaken in two mallee (Eucalyptus spp.) communities in south-western New South Wales to determine range and variability in the number and density of potential regeneration sites. Lignotuber size ranged from 2.5 to 610 kg in weight and from 2.7 to 495 L in volume while total bud number per lignotuber (92–13300) and bud density (76–450 buds per 100 cm ² of lignotuber surface area) showed no consistent interrelationships. Eight months after a prescribed fire applied in late spring, total number of buds activated per lignotuber ranged from 14 to 307 but rarely exceeded 100. Most coppices had 5–15 emergent fascicles by this stage, most (80%) of which originated in the surface 8 cm. At this time, an average of only 22.5 ± 1.0% of the total buds activated per lignotuber emerged above the soil surface. Five years after decapitation treatments had been applied, 99% of the variation in coppice biomass could be attributed to the negative relationship between cumulative coppice biomass and the proportion of original fascicles decapitated. All mallee plants died after 100% of fascicles were decapitated in the autumn for two consecutive years following an initial fire.