The Effects of Natural Disturbances on Warm Temperate Rain-Forests in South-Eastern Australia

Abstract

The effects of fire, flood and landslide disturbance on the floristics and structure of some warm temperate rainforests in East Gippsland were investigated from 1983 to 1989. Subcommunities within these forests were delineated by the numerical analyses of floristic data. In moister sites, relatively undisturbed rainforest is dominated by Acmena smithii in association with Acronychia oblongifolia and Rapanea howittiana together with numerous vines and ferns. The size-class distributions of the major tree species indicate that these forests are regenerating. In riparian habitats, Tristaniopsis laurina tends to dominate due to its greater flood resistance whereas Pittosporum undulatum becomes prominent in edaphically drier sites. Within burnt rainforest A. smithii and T. laurina have regenerated vegetatively but P. undulatum has been eliminated. In adjacent wet sclerophyll forest subsequent invasion by rainforest seedlings has occurred. In gorges, landslides may cause disturbance to various degrees and subsequent colonisation is dependent upon both the site and the matrix of the material transposed. The status of the various subcommunities is discussed in terms of the environmental gradients present, the modes of regeneration and the types of primary and secondary successions initiated by the disturbances.