The use of heuristic optimization in risk management of wind damage in forest planning

In this work heuristic techniques were used with a forest growth model (SIMA), mechanistic wind damage model (HWIND) and GIS software (ArcGIS) in order to manage the risk of wind damage in forest planning. The study optimized clear-cut regimes taking into account the risk of wind damage and timber harvest over a 30-year simulation (planning) period in a forest located in central Finland. To demonstrate the effect of management goals related to wind damage, the amount of stand edges at risk was either minimized or maximized with or without even-flow targets of harvested timber. The three heuristic techniques included in the preliminary tests (simulated annealing, tabu search, and genetic algorithms) produced rather similar results for the planning problems. Tabu search performed slightly better than simulated annealing and genetic algorithms, and was therefore used in the subsequent analyses. The optimizations showed that the risk of wind damage could be decreased by aggregating clear-cuts and avoiding clear-cuts at the edge of stands with a high possibility of being damaged. The even-flow timber harvesting objective limited the possibilities of minimizing the risk of wind damage. In addition, the optimization of clear-cut regimes was sensitive to the criterion of critical wind speed that bisected the stands into risky and non-risky ones.