Mackensen J., Bauhus J. and Webber E. (2003): Decomposition rates of coarse woody debris - A review with particular emphasis on Australian tree species.
Australian Journal of Botany 51, 27-37.
This review examined the decay patterns and turnover times of coarse woody debris (CWD) situated on the ground. The aims of this review were to identify the factors influencing the decomposition process of CWD and to provide estimates of turnover times for Australian tree species. The analysis of a global data set on decay rates of CWD showed that in particular the mean annual temperature was a main driver of decomposition. This factor alone accounted for 34% of the variation in decay rates. The Q10, the factor by which biological process accelerate when the temperature increases by 10°C, which was derived from the exponential relationship between temperature and decay rate was 2.53. Additional determinants of CWD derived from the global data set were the initial density of wood and the diameter of logs. Median and average turnover rates (95% mass loss) from 184 decay rate values from the literature were 49 and 92 years respectively. The course of decay followed in most cases a negative exponential curve, indicating that it can be described best through a single-component model. To overcome the paucity of information on decomposition of CWD in Australian forest and woodland ecosystems, turnover rates for a large number of species were derived from wood durability and decay resistance studies. These turnover times ranged from 7 years in Eucalyptus regnans to 375 years in E. camaldulensis for native Australian species. The turnover times for timber durability classes 1-4 were 54, 39, 26, and 11 years below 30°C and without the influence of termites. However, the experimental conditions under which durability and decay resistance are commonly determined are substantially different from the situation under which CWD decomposes in the field. These estimates must therefore be regarded as minimum turnover times for most species.