The effect of clearfell logging on tree-ferns in Victorian Wet Forest

Abstract

Abstract The Victorian Department of Natural Resources and Environment (NRE) is evaluating the effects of logging on understorey flora, with a view to maintaining the long term ecological integrity of forest environments. An important aspect of this research has been investigations into the effect of clearfell logging practices on tree-fern survival. The tree-ferns Dicksonia antarctica and Cyathea australis are characteristic understorey species of Victorian Wet Forests. Tree-fern trunks are a major substratum for many epiphytic species and are an establishment site for some tree and shrub species. Dicksonia antarctica and C. australis can generally survive wildfire, but several researchers have reported low tree-fern occurrence in clearfelled areas. This study quantifies the effects of clearfelling on D. antarctica and C. australis one coupe in the Toolangi State Forest. Tree-ferns were monitored on five 30 x 30 m plots from before a clearfell operation to two and a half years after the operation. The tree-ferns declined substantially in number after logging. Two and a half years after clearfelling 14% remained alive and 6% remained upright. The health of surviving tree-ferns was poor when compared with tree-ferns in unlogged forest: frond lengths were shorter, fronds were shorter lived and fewer tree-ferns were fertile. Only 10% of the original trunk surface area remained on the plots after logging. As a consequence of reduced tree-fern numbers, a range of flora and fauna are also likely to be disadvantaged. For example, the reduction in trunk surface area and microclimate associated with tree-ferns is likely to influence the distribution of epiphytic flora. These results have implications for the future management of Victorian Wet Forest. Modified silvicultural techniques could improve the survival of tree-ferns during logging.