Optimal management of Pinus pinaster in Galicia (Spain) under risk of fire

Pinus pinaster is the most important conifer in Galicia in terms of volume and production, occurs mainly in plantations. Forest fires are the main threat to forest plantations, affecting optimal stand management. The aim of this study was to develop management prescriptions for P. pinaster based on growth and yield models and optimisations. The objective function was soil expectation value, calculated taking the expected fire losses into account. Fire risk was assumed to consist of two components, probability of occurrence and damage. As the main cause of forest fires in Galicia is arson, the manager cannot significantly influence fire occurrence, which was assumed to be exogenous. Salvage was treated as an endogenous factor depending on the management schedule followed in the stand. Optimisations were done for different initial stands, timber assortments, discount rates and probabilities of fire occurrence. Based on the optimisation results, regression models were developed for the optimal rotation length as well as the timing and intensity of thinnings. The results show that when fire risk is partly endogenous, optimal rotation lengths become shorter with increasing probability of fire occurrence, and optimal thinning becomes heavier and earlier. However, without a price reduction for burned timber, the optimal rotation length increases with increasing probability of fire.