Colonization by Bryophytes of Burned Eucalyptus Forest in Tasmania, Australia: Changes in Biomass and Element Content

Bryophytes became established about three months after a high intensity slash burn after logging a high quality eucalypt/rainforest site in the Picton River region of southeastern Tasmania. Some successional change among species occurred, but the biomass of the bryophytes remained fairly constant at 140-180 g m-2 from 14 to 38 months after burning. The mineral element contents were considerably different among species, with high concentra- tions of nitrogen in Polytrichum juniperinum, and of potassium in Marchantia berteroana, and low concentrations of all elements in Campylopus introflexus. For each species, there were consis- tent decreases in the contents of nitrogen, phosphorus, potassium, and calcium, but not magnesium, with increasing time since the fire. In Tasmania, mixed eucalypt forest with high quality timber is managed for sawlogs and pulp- wood. Forestry operations normally involve clear- felling and burning of residual debris and slash. Al- though the larger logs remain after the fire, it is common for nearly all the fuel less than 25 cm in diameter to be consumed. A substantial amount of ash is deposited because of the very large quantities of fuel. The only study in southern Tasmania (Har- wood & Jackson 1975) estimated the amount of fuel before the fire to be 63.3 kg m-2 and the ash layer after the fire to be 1.22 kg m-2. In recent years there has been considerable discussion of the ecological impact of these high intensity fires (Harwood & Jackson 1975; Raison 1980; Ellis et al. 1982) be- cause of the potential losses of nutrients from the site both during the fire by volatilization and aerial dispersal of ash, and after the fire by leaching and soil erosion. After a regeneration burn in Tasmanian forests, the sites are rapidly colonized by bryophytes (Dun- can & Dalton 1982). Six months after the burn (by the following spring), at one site about 50% of the ground was covered by bryophytes, and after 24 months a 90% bryophyte cover left only 10% of the ground bare (Duncan & Dalton 1982). Bryophytes are an important but little studied