Exploring controls of timber stock residence times in storage after severe storm events

The storage of significant amounts of timber from thrown or dead trees after natural disturbances is an established practice for forest enterprises. Timber storage mitigates economic losses caused by supply-driven timber price falls after natural disturbances. We use a forest accounting database to explore the controls of residence times of coniferous timber stocks in storage following severe storm events. We characterize forest enterprises’ timber stock outflow distributions from storage over several years by mean residence times and their variances. We conduct regression analyses on the expected residence times and their variances. We assess the significance of several explanatory variables representing economic, institutional and tree species-related factors on these metrics using multiple linear regression analyses. Illustrating the effect of these variables on timber storage residence time distributions we reanalyze the database by grouping the FADN data sets with regard to the identified control variables and determine their mean timber storage outflow distributions after the storm events as well as associated expected residence times and their variances. Applying the resulting parameters with the continuous gamma distribution to simulate TSO residence time distributions clearly illuminates the effect of the control variables on storage management. We show that besides market price dynamics, species groups, ownership categories and forest worker capacities are statistically significant controls for mean residence times of timber stock in storage and their variances. We find that stronger timber price falls correlate with shorter mean residence times of timber stocks in storage. We relate this to liquidity maintenance of forest enterprises. We model duration times parameterizing the Gamma distribution. The application of the Gamma distribution to characterize storage management behavior offers the potential to describe differences in timber stock quantities even on shorter timescales than the mean storage residence times. According to our results, we propose to assess timber stocks in storage over a multi-year period in order to improve related national and international accounting schemes.