Population biology of coppicing plants: survival of mallee (Eucalyptus spp.) populations exposed to contrasting fire and cutting regimes

Abstract

We examined data obtained from two experiments running concurrently over an 8-year period, designed to investigate the survival of mallee eucalypts exposed to various decapitation treatments applied by either fire or axe at contrasting frequencies. Annual autumn decapitation, with or without combined spring decapitation, gave the most rapid rates of depletion. The estimated half-life, i.e. time to 50% mortality, ranged from 278 days when both autumn and spring fires were applied annually, up to 3366 days when plants were cut by axe every fourth autumn. These were followed in turn by autumn decapitation every second year, then spring annually and autumn every third year and finally autumn decapitation imposed every fourth year. With the marginal exception of one treatment (burnt every third autumn), the estimated rates of depletion were greater for the burning treatments than for their cutting counterparts. The ranking of the six treatments by estimated rates of depletion was the same in both the fire and cutting trials. Prescribed fire is a powerful and cost-effective management tool for manipulating semiarid woodlands in temperate Australia. In addition to reducing grass and litter fuel, prescribed fire has the potential to promote herbage production for domestic livestock. We provide clear evidence based on field experiments that a management strategy based on relatively frequent fires applied in the autumn will significantly reduce mallee density, thereby promoting herbage productivity.