Evaluating the effects of forest management on rockfall protection and timber production at slope scale

We used the coupled forest and rockfall model PICUS Rock'n'Roll, linking a hybrid forest patch model and a 3D rockfall model, to assess the effects of four management scenarios (BAU: business as usual age class shelterwood approach; PFM1 and PFM2: rockfall protection management scenarios with slit-shaped gaps; NOM: no management scenario without any active silvicultural intervention) on rockfall protection and timber production on a 38 ha slope over 100 years. Compared to PFM1 and PFM2, we found slightly more harvested timber for the BAU scenario (BAU: 6.7m(3)ha(-1)yr(-1), PFM: 5.7-5.9m(3)ha(-1)yr(-1)), but lower contribution margins (BAU: 55Euroha(-1)yr(-1), PFM: 113-115Euroha(-1)yr(-1)). Overall, depending on rock size and forest state, 30-70% of the simulated rocks that would otherwise hit the road at the foot of the slope were stopped by the forest. While the PFM scenarios maintained a high rockfall protection level over 100 years (PE between 45-64%) the BAU showed periods of reduced protection (PE between 26-65%). The NOM scenario maintained favorable conditions in the beginning, but declining protection efficiency in the last decades of the century (PE 49-63%). We conclude that rockfall protection management can outperform BAU with regard to both timber production and rockfall protection.