Effect of the estimation of forest management and decay of dead woody material on the reliability of carbon stock and carbon stock changes—A simulation study

The IPCC-GPG on Greenhouse Gas Monitoring offers countries several options for reporting. The current study selected management effects and decay of dead woody material to demonstrate the dependence of different approaches and assumptions for carbon stock and carbon stock change estimates. For a given set of inventory data the reported change of carbon stock varied between 3.1 tonnes C ha −1 yr −1and 34.4 tonnes C ha −1 yr −1 for a 10-year period. Based on the available data set from a test area in the federal state of Salzburg (Austria) the effect of different scenarios for harvesting operations and mortality on reported carbon release was studied. The scenarios covered timber utilization at different points in time and two mortality rates (constant and exponential). A proportion of harvesting was assumed to remain inside the forest as logging residues and entered together with mortality a decay process. Two different lifetimes for decay (10 and 50 years) and constant and negative exponential decay rates were simulated. Those decisions affect the amount of carbon released considerably. For a 10-year period between 5% and 80% of the carbon content of dead woody material that accumulated within the period is released to the atmosphere.