THE INFLUENCE OF PACK SIZE AND POSITION, LEAF TYPE, AND SHREDDER ACCESS ON THE PROCESSING RATE OF ATHEROSPERMA-MOSCHATUM LEAVES IN AN AUSTRALIAN COOL TEMPERATE RAIN-FOREST STREAM

Factors affecting the processing rate of packs of southern sassafras ( Atherosperma moschatum) leaves were investigated in an Australian cool temperate rainforest stream pool. Processing rate was strongly influe nced by pack weight fitting a linear inverse relationship. Processing was not significantly (p > 0.05) affected by whether the packs were pl aced on bricks or free on the stream bed. Free packs, but not packs on bricks, were processed more rapidly near the bank than in midstream ( p = 0.050). Packs placed in 300 mum mesh bags, with one side unsealed were processed at the same rate as packs attached to bricks or free on the stream bed, but packs in sealed 300 mum mesh bags were processed significantly more slowly (p < 10(-4)). Abscissed leaves were processe d significantly more slowly than fresh leaves (p < 10(-5)) and at a ra te not significantly different to leaves sealed in mesh bags (p = 0.19 7). There was no consistent pattern of difference between processing r ates in summer and winter. The results indicate that the size of litte r packs may be a more important factor in influencing processing rate estimates than the method of attachment of the packs. The slow rate of processing of abscissed leaves compared with fresh leaves indicates t hat they were at most, slightly influenced by stream shredders. The ab sence of a consistent pattern of difference between summer and winter processing rates is consistent with the results of previous litter pro cessing studies from southeastern Australia although no clear causal f actor can be identified.