Breakdown of Four Litters of Contrasting Quality in a Tropical Australian Rainforest

Abstract

(1) Using litter bags, the rates of breakdown of the litter of Pinus caribaea, Araucaria cunninghamii and Eucalyptus alba were compared with that of a mixed-species rainforest litter in a lowland tropical rainforest. (2) The litter was exposed during the early part of the summer wet season and compared for 253 days; more than 1660 mm of rain was recorded during this time. (3) The rate of litter breakdown decreased in the order: E. alba > (mixed species rainforest, A. cunninghamii) > P. caribaea. (4) Excluding arthropods from the litter using coarse and fine-mesh bags showed that the mixed-species rainforest litter and that of E. alba were attractive to arthropods while that of P. caribaea was not; the litter of A. cunninghamii was excluded from this comparison. (5) In all litter, breakdown rates were not simply related to the initial contents of elements, neutral detergent fibre or acid-detergent lignin. (6) Three commonly used regression models were fitted to the data; exponential models provided satisfactory fits to the data from all except the resistant litter of P. caribaea where an asymptotic model proved appropriate.