The role of fallen logs in the regeneration of tree species in Tasmanian mixed forest.

Abstract

This study was designed to determine whether fallen logs were a more favourable habitat for tree species establishment than soil in moist eucalypt forest in Tasmania, whether establishment success on logs varied between two forests in contrasting environments, and whether surface and substrate qualities and light conditions were associated with establishment success. Data on tree and shrub species densities and heights by species, moss cover, litter cover, Blechnum wattsii cover, canopy cover, bulk density of the substrate, and substrate surface pH, nitrogen content and phosphorus content were obtained from paired soil and log quadrats. Tree seedlings were found to be significantly more abundant on fallen logs than on adjacent ground at both sites, with the differences being greater at the moister Tahune site than at Mount Field. At Tahune, logs significantly differed from adjacent soil in canopy cover, litter cover, moss cover Blechnum wattsii cover, pH and slope. At Mount Field, there were significant differences between logs and soil in litter cover, moss cover, pH, bulk density and nitrogen. Litter cover may be critical in explaining the superior establishment of trees on logs rather than soil in Tasmanian mixed forest, although the possible impacts of variations in bioturbation and root competition require further research.