Dead wood matters - a snapshot in time of one hectare of the floor of a eucalyptus obliqua forest in Southern Tasmania

Wildfires in wet eucalypt forests, depending on their intensity and frequency, generate dead wood of varying sizes and in many different stages of decay. Windthrow events also contribute to large dead wood lying on the forest floor. In this study, CWD (coarse woody debris), defined as dead wood at least 10 cm diameter and 1 m long, and dead standing trees (stags) were measured and their attributes recorded in four 50 x 50 m plots within ca. 1 km of each other but with differing wildfire histories in a tall, wet, native Eucalyptus obliqua forest in southern Tasmania. Maps of the CWD and stags for each of the four plots were drawn and show substantial differences between the four plots. Information from four other surveys of CWD in the same forest type provided a degree of replication to this study. Comparisons among the studies showed that the CWD volumes in plots of similar age since wildfire were very variable and most likely reflect the chance location of large fallen eucalypts in the plots. This suggests that more surveys such as these are needed to determine the average CWD volumes in these forests. Knowledge of these volumes is required to develop forest dynamics models to predict the amount of CWD that would be present as a result of various disturbance and management scenarios. Dead wood is seen to be an important resource in these tall, wet forests, harbouring biodiversity and storing carbon. The challenge for the Tasmanian forest industry in the future may involve the development of energy-efficient methods so that mixed forests, which store carbon to a greater extent than pure eucalypt forest or pure rainforest, can produce wood products such as furniture, floors, veneers and musical instruments and do it in a manner that minimises carbon loss, to make no net contribution to global warming.