In an early spar-stage stand of Eucalyptus regnans at Beenak, Victoria, foraging by lyrebirds in bare floor areas on steep slopes results in a complex microtopography of excavations, accumulations and terracettes. About 2001 ha"' of litter and top soil may be displaced an average of 70 cm downhill per year. Magnetic ferruginous pisolite was used as a marker to monitor progressive soil movement over 3 years. Very little disturbance occurred in areas of dense ground fern, but in bare areas the whole forest floor may be turned over every 20 months. In the site studied, foraging activity by lyrebirds varied seasonally and topographically. Disturbance by other biotic agents was minimal. The mean depth of soil cultivation was about 10 cm and litter was frequently buried or mixed intimately with soil. Since buried leaf litter decays more quickly than that on the surface, lyrebird foraging is likely to increase the rate of nutrient cycling. The small, steep clifflets left at the uphill limits of each scratch microsite provide litter-free niches for the establishment of tree fern prothalli and shade-tolerant herbs. All stages in the growth of the rough tree fern, Gyathea australis, were present in bare floor areas, but in dense ground fern patches, young stages were confined to rotten logs and upturned root balls. Since dense tree fern development tends to diminish the cover of dense ground fern, lyrebird foraging activity may maintain an accessible food resource which would otherwise diminish with increased ground fern cover in these forests in the course of secondary succession after fire.
Eucalyptus sieberi L.Johnson (silvertop ash) and E. globoidea Blakely (white stringybark) are two important timber species from East Gippsland, Victoria, where their regeneration following timber harvesting is usually attempted using the seed tree silvicultural system. Their seed crop development processes have not been well documented, however, and the information available for E. globoidea appears to contain inconsistencies. Consequently, this study was initiated, during the establishment of the Silvicultural Systems Project experiment near Cabbage Tree Creek, East Gippsland, to describe the morphological development of seed crops in the two species, and to determine the quantities, variation and losses associated with each stage in that development.Eight funnel seed traps were located on a duplex soil site which supported a stand composed of 67% E. sieberi and 33% E. globoidea, by basal area. They were monitored at intervals of about a fortnight over the period from February 1989 to November 1992. A further six traps were located under individual trees of E. globoidea on a uniform sand site and were monitored for the period from February to December 1991. The timing, rates of fall and total fall of reproductive material at each site were determined. The results are reported here and some silvicultural implications are discussed.
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