Rates of litterfall over a period of 3 y at one undisturbed site and two sites disturbed by selective harvesting are reported for a tropical rain forest area in North Queensland, Australia. Litterfall over a period of 18 months is also reported for a further undisturbed site in the same area. No significant differences were found in annual litterfall between the sites, with annual litterfall rates ranging from 5.0 to 6.0 t ha−1 y−1. These rates are considerably lower than those reported for other rain forest areas in Australia, and are within the lower ranges recorded for other tropical rain forests. Litterfall was found to be strongly seasonal at all sites with the maximum falls occurring from the end of the dry season to the end of the wet season. The between year variability of the sites was quite low, with the ratio of maximum to minimum production ranging from 1.05 to 1.20. The average percentages of leaves, wood and reproductive material in litterfall were similar at each site. Leaves were the dominant component of litterfall with the average proportion of the total litterfall ranging from 72% to 76% over the study period at each of the four sites. At certain times, however, the fall of wood and reproductive material was quite significant, comprising as much as 71% and 34% of litterfall respectively. A strong negative correlation was found between the fall of leaves and wood at all sites.

This paper introduces studies of nutrient cycling in disturbed and undisturbed rain forest plots in the upper catchment of Birthday Creek, near Paluma, North Queensland. The catchment is underlain by granite and has soils of comparatively low fertility. Differences between unlogged plots and plots disturbed 25 years previously by selective logging are still apparent. Disturbed plots have soils with higher bulk densities and pH, lower CEC, kjeldahl nitrogen and available phosphorus concentrations, and changed species composition. The data suggest that recovery from selective logging is dependent on soil fertility and intensity of disturbance.

The nutrient contents and accessions in litterfall over a period of 3 y are reported for undisturbed areas and at two sites disturbed by selective harvesting in tropical rain forest in North Queensland, Australia. Mean concentrations (mg g&supminus1; dry weight) of nutrients in litterfall ranged from 10 to 12 for nitrogen; 0.33 to 0.43 for phosphorus; 3.6 to 4.3 for potassium; 6.0 to 10.5 for calcium; and 1.7 to 2.6 for magnesium. These concentrations are in the middle to lower part of the spectrum of values recorded for tropical forests. Accessions of nutrients in litterfall (kg ha&supminus1; y&supminus1;) ranged from 59 to 64 N; 1.9 to 2.4 P; 20 to 24 K; 34 to 63 Ca; and 9 to 16 Mg. These rates, particularly for N and P, are among the lowest recorded for tropical forests. There were no consistent between-site differences in total nutrient accessions in small litterfall. In terms of the contribution of litterfall to the accessions of nutrients to the forest floor, this suggests that the logged sites have recovered from the effects of selective harvesting within 25 y. Nutrient accessions at each site were distinctly seasonal, with maximum accessions occurring in the late dry season to late in the wet season. Leaf-fall accounted for the largest proportion of nutrient accessions over the study period, although at certain times accessions in both reproductive material and wood were significant. A cyclone which crossed the coast near the study sites resulted in large nutrient accessions over a short period but had little effect on the total annual accession. A comparison with previous studies of litterfall in Australian tropical rainforests indicates that nutrient return in litterfall is directly related to soil fertility.