Modelling long-term effects of forest dynamics on the protective effect against rockfall

Bern

2006

S. 57-76

4 Abb., 10 Tab., 48 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

200137329

Forest dynamics have long-term impacts on the effectiveness of mountain forests in providing protection against natural hazards, but these are difficult to study because of the long time periods involved. We addressed this difficulty using simulation models, combining the forest patch model ForClim with the rockfall model RockForNET, and applying the combined simulation tool to a case study. Based on empirical data, we simulated the development of three mountain forests assuming different developmental scenarios over a period of 60 years. The protective effect of the simulated stands was then assessed using a site in the Swiss Alps where data on the terrain and rock characteristics were available. This enabled us to determine the factors that are important for maintaining the long-term protective effect of a mountain forest. - The long-term protective effect of the stands against rockfall was generally high for small rocks, but limited for larger rocks (diameter > 0.8 m), indicating that there is a limit to the protective potential of stands on the slope. Key factors for effective protection over the 60 years were a high initial stand density and a relatively low mortality rate. A high density of tree regeneration in the initial stand was also found to increase the long-term protective effect against small rocks, but not against larger rocks. - The modelling approach used could be improved by extending the forest dynamics model beyond 60 years and by including a more detailed representation of tree diameter distributions in the rockfall model.