Litter studies in the southern forests of Tasmania

Process oriented investigations of litter were made at Hastings, Southern Tasmania, of a range of forests characteristic of the region. \\({Accession.}\\) There was a marked seasonal pattern and correspondence of litterfall between sites over three annual cycles. Bimodality of litterfall was attributable to a peak period of leaf fall and a period of bark and twig fall. Leaf litterfall was significantly correlated with mean maximum temperature, and the secondary peak of bark and twig fall to periods of high wind and heavy rain. A relationship was found between the basal area of individual species and their annual rate of leaf accession. There was no significant difference in slope or intercept of regressions for individual sites, and the relationship existed for all species regardless of their taxonomic group, canopy exposure, or leaf structure and size classification. Annual accession rates were similar to forests of the world of corresponding latitude (ca. 5 t.ha.\\(^{-1}\\)). \\({Accumulation.}\\) Detailed descriptions were made of the litterbed characteristics of individual study sites, and techniques for improving determination of standing-crop values devised. Steady-state decay constants were derived, and a climatic index utilised to compare results of Australian litter studies. \\({Decomposition.}\\) The rates of decomposition of leaves of two eucalypt overstorey species, eight understorey species, and of two overstorey-understorey species mixtures were measured by litter bag techniques. Percentage loss of initial dry weight of leaves varied per species from 12.5 to 58.0 over the initial twelve months of field exposure. Species of higher leaf accession rate generally exhibited a faster rate of decomposition. There were no significant between species interactions monitored in leaf mixtures. Litterbed microflora were demonstrated to be the primary decomposer agencies, with bacteria of initial importance to some species. Macroarthropods and invertebrates demonstrated no significant effects upon the decomposition rates of leaf species other than the eucalypts within the time sequence of the litter bag studies. The role of litter fauna is considered secondary to, and dependent upon, decomposition by other agencies. A method of measuring the decomposition of naturally accumulating litter in the field was devised. Temperature and moisture, as represented by a defined annual climatic index, 'I', were significantly related to annual litter accession and calculated annual decay constants, 'k', for a range of Australian litter studies. Litter macroclimate was thus the most important influence upon litter accumulation.