A timber harvesting model for Austria

Between 1981 and 1985 the Austrian National Forest Inventory (ANF) established a set of 5500 clusters, each with four permanent plots covering all Austrian forests. After the first remeasurement between 1986 and 1990 models were developed to predict tree growth, mortality and the behavior of forest owners in harvesting timber. A set of logistic equations describes the probability for a given stand to exhibit intermediate harvesting, single-tree selection or final clear cutting. Independent variables were either continuous or categorical, describing: (i) regional units such as provinces, (ii) types of ownership (groups of ownership sizes), (iii) site factors (elevation and slope), and (iv) stand characteristics (species mixture, density, mean diameter). Timber removals on the plots are recorded by five relative diameter at breast height (dbh)-classes. Removal percentages differ by elevation, harvesting categories, and tree species groups. Timber harvest forecasts and their spatial arrangement over Austria in the following four 5-year periods were made available to the public using computer software. In 1997 data of the second inventory remeasurements were available and thus the forecasts for this period could be evaluated. When forecast units are large enough, deviations from the model are either small or can be explained by a different timber market scenario and/or a general socio-economical scenario.